linux/drivers/video/udlfb.c
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   1/*
   2 * udlfb.c -- Framebuffer driver for DisplayLink USB controller
   3 *
   4 * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
   5 * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
   6 * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
   7 *
   8 * This file is subject to the terms and conditions of the GNU General Public
   9 * License v2. See the file COPYING in the main directory of this archive for
  10 * more details.
  11 *
  12 * Layout is based on skeletonfb by James Simmons and Geert Uytterhoeven,
  13 * usb-skeleton by GregKH.
  14 *
  15 * Device-specific portions based on information from Displaylink, with work
  16 * from Florian Echtler, Henrik Bjerregaard Pedersen, and others.
  17 */
  18
  19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21#include <linux/module.h>
  22#include <linux/kernel.h>
  23#include <linux/init.h>
  24#include <linux/usb.h>
  25#include <linux/uaccess.h>
  26#include <linux/mm.h>
  27#include <linux/fb.h>
  28#include <linux/vmalloc.h>
  29#include <linux/slab.h>
  30#include <linux/prefetch.h>
  31#include <linux/delay.h>
  32#include <video/udlfb.h>
  33#include "edid.h"
  34
  35static struct fb_fix_screeninfo dlfb_fix = {
  36        .id =           "udlfb",
  37        .type =         FB_TYPE_PACKED_PIXELS,
  38        .visual =       FB_VISUAL_TRUECOLOR,
  39        .xpanstep =     0,
  40        .ypanstep =     0,
  41        .ywrapstep =    0,
  42        .accel =        FB_ACCEL_NONE,
  43};
  44
  45static const u32 udlfb_info_flags = FBINFO_DEFAULT | FBINFO_READS_FAST |
  46                FBINFO_VIRTFB |
  47                FBINFO_HWACCEL_IMAGEBLIT | FBINFO_HWACCEL_FILLRECT |
  48                FBINFO_HWACCEL_COPYAREA | FBINFO_MISC_ALWAYS_SETPAR;
  49
  50/*
  51 * There are many DisplayLink-based graphics products, all with unique PIDs.
  52 * So we match on DisplayLink's VID + Vendor-Defined Interface Class (0xff)
  53 * We also require a match on SubClass (0x00) and Protocol (0x00),
  54 * which is compatible with all known USB 2.0 era graphics chips and firmware,
  55 * but allows DisplayLink to increment those for any future incompatible chips
  56 */
  57static struct usb_device_id id_table[] = {
  58        {.idVendor = 0x17e9,
  59         .bInterfaceClass = 0xff,
  60         .bInterfaceSubClass = 0x00,
  61         .bInterfaceProtocol = 0x00,
  62         .match_flags = USB_DEVICE_ID_MATCH_VENDOR |
  63                USB_DEVICE_ID_MATCH_INT_CLASS |
  64                USB_DEVICE_ID_MATCH_INT_SUBCLASS |
  65                USB_DEVICE_ID_MATCH_INT_PROTOCOL,
  66        },
  67        {},
  68};
  69MODULE_DEVICE_TABLE(usb, id_table);
  70
  71/* module options */
  72static bool console = 1; /* Allow fbcon to open framebuffer */
  73static bool fb_defio = 1;  /* Detect mmap writes using page faults */
  74static bool shadow = 1; /* Optionally disable shadow framebuffer */
  75static int pixel_limit; /* Optionally force a pixel resolution limit */
  76
  77/* dlfb keeps a list of urbs for efficient bulk transfers */
  78static void dlfb_urb_completion(struct urb *urb);
  79static struct urb *dlfb_get_urb(struct dlfb_data *dev);
  80static int dlfb_submit_urb(struct dlfb_data *dev, struct urb * urb, size_t len);
  81static int dlfb_alloc_urb_list(struct dlfb_data *dev, int count, size_t size);
  82static void dlfb_free_urb_list(struct dlfb_data *dev);
  83
  84/*
  85 * All DisplayLink bulk operations start with 0xAF, followed by specific code
  86 * All operations are written to buffers which then later get sent to device
  87 */
  88static char *dlfb_set_register(char *buf, u8 reg, u8 val)
  89{
  90        *buf++ = 0xAF;
  91        *buf++ = 0x20;
  92        *buf++ = reg;
  93        *buf++ = val;
  94        return buf;
  95}
  96
  97static char *dlfb_vidreg_lock(char *buf)
  98{
  99        return dlfb_set_register(buf, 0xFF, 0x00);
 100}
 101
 102static char *dlfb_vidreg_unlock(char *buf)
 103{
 104        return dlfb_set_register(buf, 0xFF, 0xFF);
 105}
 106
 107/*
 108 * Map FB_BLANK_* to DisplayLink register
 109 * DLReg FB_BLANK_*
 110 * ----- -----------------------------
 111 *  0x00 FB_BLANK_UNBLANK (0)
 112 *  0x01 FB_BLANK (1)
 113 *  0x03 FB_BLANK_VSYNC_SUSPEND (2)
 114 *  0x05 FB_BLANK_HSYNC_SUSPEND (3)
 115 *  0x07 FB_BLANK_POWERDOWN (4) Note: requires modeset to come back
 116 */
 117static char *dlfb_blanking(char *buf, int fb_blank)
 118{
 119        u8 reg;
 120
 121        switch (fb_blank) {
 122        case FB_BLANK_POWERDOWN:
 123                reg = 0x07;
 124                break;
 125        case FB_BLANK_HSYNC_SUSPEND:
 126                reg = 0x05;
 127                break;
 128        case FB_BLANK_VSYNC_SUSPEND:
 129                reg = 0x03;
 130                break;
 131        case FB_BLANK_NORMAL:
 132                reg = 0x01;
 133                break;
 134        default:
 135                reg = 0x00;
 136        }
 137
 138        buf = dlfb_set_register(buf, 0x1F, reg);
 139
 140        return buf;
 141}
 142
 143static char *dlfb_set_color_depth(char *buf, u8 selection)
 144{
 145        return dlfb_set_register(buf, 0x00, selection);
 146}
 147
 148static char *dlfb_set_base16bpp(char *wrptr, u32 base)
 149{
 150        /* the base pointer is 16 bits wide, 0x20 is hi byte. */
 151        wrptr = dlfb_set_register(wrptr, 0x20, base >> 16);
 152        wrptr = dlfb_set_register(wrptr, 0x21, base >> 8);
 153        return dlfb_set_register(wrptr, 0x22, base);
 154}
 155
 156/*
 157 * DisplayLink HW has separate 16bpp and 8bpp framebuffers.
 158 * In 24bpp modes, the low 323 RGB bits go in the 8bpp framebuffer
 159 */
 160static char *dlfb_set_base8bpp(char *wrptr, u32 base)
 161{
 162        wrptr = dlfb_set_register(wrptr, 0x26, base >> 16);
 163        wrptr = dlfb_set_register(wrptr, 0x27, base >> 8);
 164        return dlfb_set_register(wrptr, 0x28, base);
 165}
 166
 167static char *dlfb_set_register_16(char *wrptr, u8 reg, u16 value)
 168{
 169        wrptr = dlfb_set_register(wrptr, reg, value >> 8);
 170        return dlfb_set_register(wrptr, reg+1, value);
 171}
 172
 173/*
 174 * This is kind of weird because the controller takes some
 175 * register values in a different byte order than other registers.
 176 */
 177static char *dlfb_set_register_16be(char *wrptr, u8 reg, u16 value)
 178{
 179        wrptr = dlfb_set_register(wrptr, reg, value);
 180        return dlfb_set_register(wrptr, reg+1, value >> 8);
 181}
 182
 183/*
 184 * LFSR is linear feedback shift register. The reason we have this is
 185 * because the display controller needs to minimize the clock depth of
 186 * various counters used in the display path. So this code reverses the
 187 * provided value into the lfsr16 value by counting backwards to get
 188 * the value that needs to be set in the hardware comparator to get the
 189 * same actual count. This makes sense once you read above a couple of
 190 * times and think about it from a hardware perspective.
 191 */
 192static u16 dlfb_lfsr16(u16 actual_count)
 193{
 194        u32 lv = 0xFFFF; /* This is the lfsr value that the hw starts with */
 195
 196        while (actual_count--) {
 197                lv =     ((lv << 1) |
 198                        (((lv >> 15) ^ (lv >> 4) ^ (lv >> 2) ^ (lv >> 1)) & 1))
 199                        & 0xFFFF;
 200        }
 201
 202        return (u16) lv;
 203}
 204
 205/*
 206 * This does LFSR conversion on the value that is to be written.
 207 * See LFSR explanation above for more detail.
 208 */
 209static char *dlfb_set_register_lfsr16(char *wrptr, u8 reg, u16 value)
 210{
 211        return dlfb_set_register_16(wrptr, reg, dlfb_lfsr16(value));
 212}
 213
 214/*
 215 * This takes a standard fbdev screeninfo struct and all of its monitor mode
 216 * details and converts them into the DisplayLink equivalent register commands.
 217 */
 218static char *dlfb_set_vid_cmds(char *wrptr, struct fb_var_screeninfo *var)
 219{
 220        u16 xds, yds;
 221        u16 xde, yde;
 222        u16 yec;
 223
 224        /* x display start */
 225        xds = var->left_margin + var->hsync_len;
 226        wrptr = dlfb_set_register_lfsr16(wrptr, 0x01, xds);
 227        /* x display end */
 228        xde = xds + var->xres;
 229        wrptr = dlfb_set_register_lfsr16(wrptr, 0x03, xde);
 230
 231        /* y display start */
 232        yds = var->upper_margin + var->vsync_len;
 233        wrptr = dlfb_set_register_lfsr16(wrptr, 0x05, yds);
 234        /* y display end */
 235        yde = yds + var->yres;
 236        wrptr = dlfb_set_register_lfsr16(wrptr, 0x07, yde);
 237
 238        /* x end count is active + blanking - 1 */
 239        wrptr = dlfb_set_register_lfsr16(wrptr, 0x09,
 240                        xde + var->right_margin - 1);
 241
 242        /* libdlo hardcodes hsync start to 1 */
 243        wrptr = dlfb_set_register_lfsr16(wrptr, 0x0B, 1);
 244
 245        /* hsync end is width of sync pulse + 1 */
 246        wrptr = dlfb_set_register_lfsr16(wrptr, 0x0D, var->hsync_len + 1);
 247
 248        /* hpixels is active pixels */
 249        wrptr = dlfb_set_register_16(wrptr, 0x0F, var->xres);
 250
 251        /* yendcount is vertical active + vertical blanking */
 252        yec = var->yres + var->upper_margin + var->lower_margin +
 253                        var->vsync_len;
 254        wrptr = dlfb_set_register_lfsr16(wrptr, 0x11, yec);
 255
 256        /* libdlo hardcodes vsync start to 0 */
 257        wrptr = dlfb_set_register_lfsr16(wrptr, 0x13, 0);
 258
 259        /* vsync end is width of vsync pulse */
 260        wrptr = dlfb_set_register_lfsr16(wrptr, 0x15, var->vsync_len);
 261
 262        /* vpixels is active pixels */
 263        wrptr = dlfb_set_register_16(wrptr, 0x17, var->yres);
 264
 265        /* convert picoseconds to 5kHz multiple for pclk5k = x * 1E12/5k */
 266        wrptr = dlfb_set_register_16be(wrptr, 0x1B,
 267                        200*1000*1000/var->pixclock);
 268
 269        return wrptr;
 270}
 271
 272/*
 273 * This takes a standard fbdev screeninfo struct that was fetched or prepared
 274 * and then generates the appropriate command sequence that then drives the
 275 * display controller.
 276 */
 277static int dlfb_set_video_mode(struct dlfb_data *dev,
 278                                struct fb_var_screeninfo *var)
 279{
 280        char *buf;
 281        char *wrptr;
 282        int retval = 0;
 283        int writesize;
 284        struct urb *urb;
 285
 286        if (!atomic_read(&dev->usb_active))
 287                return -EPERM;
 288
 289        urb = dlfb_get_urb(dev);
 290        if (!urb)
 291                return -ENOMEM;
 292
 293        buf = (char *) urb->transfer_buffer;
 294
 295        /*
 296        * This first section has to do with setting the base address on the
 297        * controller * associated with the display. There are 2 base
 298        * pointers, currently, we only * use the 16 bpp segment.
 299        */
 300        wrptr = dlfb_vidreg_lock(buf);
 301        wrptr = dlfb_set_color_depth(wrptr, 0x00);
 302        /* set base for 16bpp segment to 0 */
 303        wrptr = dlfb_set_base16bpp(wrptr, 0);
 304        /* set base for 8bpp segment to end of fb */
 305        wrptr = dlfb_set_base8bpp(wrptr, dev->info->fix.smem_len);
 306
 307        wrptr = dlfb_set_vid_cmds(wrptr, var);
 308        wrptr = dlfb_blanking(wrptr, FB_BLANK_UNBLANK);
 309        wrptr = dlfb_vidreg_unlock(wrptr);
 310
 311        writesize = wrptr - buf;
 312
 313        retval = dlfb_submit_urb(dev, urb, writesize);
 314
 315        dev->blank_mode = FB_BLANK_UNBLANK;
 316
 317        return retval;
 318}
 319
 320static int dlfb_ops_mmap(struct fb_info *info, struct vm_area_struct *vma)
 321{
 322        unsigned long start = vma->vm_start;
 323        unsigned long size = vma->vm_end - vma->vm_start;
 324        unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
 325        unsigned long page, pos;
 326
 327        if (offset + size > info->fix.smem_len)
 328                return -EINVAL;
 329
 330        pos = (unsigned long)info->fix.smem_start + offset;
 331
 332        pr_notice("mmap() framebuffer addr:%lu size:%lu\n",
 333                  pos, size);
 334
 335        while (size > 0) {
 336                page = vmalloc_to_pfn((void *)pos);
 337                if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
 338                        return -EAGAIN;
 339
 340                start += PAGE_SIZE;
 341                pos += PAGE_SIZE;
 342                if (size > PAGE_SIZE)
 343                        size -= PAGE_SIZE;
 344                else
 345                        size = 0;
 346        }
 347
 348        vma->vm_flags |= VM_RESERVED;   /* avoid to swap out this VMA */
 349        return 0;
 350}
 351
 352/*
 353 * Trims identical data from front and back of line
 354 * Sets new front buffer address and width
 355 * And returns byte count of identical pixels
 356 * Assumes CPU natural alignment (unsigned long)
 357 * for back and front buffer ptrs and width
 358 */
 359static int dlfb_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes)
 360{
 361        int j, k;
 362        const unsigned long *back = (const unsigned long *) bback;
 363        const unsigned long *front = (const unsigned long *) *bfront;
 364        const int width = *width_bytes / sizeof(unsigned long);
 365        int identical = width;
 366        int start = width;
 367        int end = width;
 368
 369        prefetch((void *) front);
 370        prefetch((void *) back);
 371
 372        for (j = 0; j < width; j++) {
 373                if (back[j] != front[j]) {
 374                        start = j;
 375                        break;
 376                }
 377        }
 378
 379        for (k = width - 1; k > j; k--) {
 380                if (back[k] != front[k]) {
 381                        end = k+1;
 382                        break;
 383                }
 384        }
 385
 386        identical = start + (width - end);
 387        *bfront = (u8 *) &front[start];
 388        *width_bytes = (end - start) * sizeof(unsigned long);
 389
 390        return identical * sizeof(unsigned long);
 391}
 392
 393/*
 394 * Render a command stream for an encoded horizontal line segment of pixels.
 395 *
 396 * A command buffer holds several commands.
 397 * It always begins with a fresh command header
 398 * (the protocol doesn't require this, but we enforce it to allow
 399 * multiple buffers to be potentially encoded and sent in parallel).
 400 * A single command encodes one contiguous horizontal line of pixels
 401 *
 402 * The function relies on the client to do all allocation, so that
 403 * rendering can be done directly to output buffers (e.g. USB URBs).
 404 * The function fills the supplied command buffer, providing information
 405 * on where it left off, so the client may call in again with additional
 406 * buffers if the line will take several buffers to complete.
 407 *
 408 * A single command can transmit a maximum of 256 pixels,
 409 * regardless of the compression ratio (protocol design limit).
 410 * To the hardware, 0 for a size byte means 256
 411 *
 412 * Rather than 256 pixel commands which are either rl or raw encoded,
 413 * the rlx command simply assumes alternating raw and rl spans within one cmd.
 414 * This has a slightly larger header overhead, but produces more even results.
 415 * It also processes all data (read and write) in a single pass.
 416 * Performance benchmarks of common cases show it having just slightly better
 417 * compression than 256 pixel raw or rle commands, with similar CPU consumpion.
 418 * But for very rl friendly data, will compress not quite as well.
 419 */
 420static void dlfb_compress_hline(
 421        const uint16_t **pixel_start_ptr,
 422        const uint16_t *const pixel_end,
 423        uint32_t *device_address_ptr,
 424        uint8_t **command_buffer_ptr,
 425        const uint8_t *const cmd_buffer_end)
 426{
 427        const uint16_t *pixel = *pixel_start_ptr;
 428        uint32_t dev_addr  = *device_address_ptr;
 429        uint8_t *cmd = *command_buffer_ptr;
 430        const int bpp = 2;
 431
 432        while ((pixel_end > pixel) &&
 433               (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
 434                uint8_t *raw_pixels_count_byte = 0;
 435                uint8_t *cmd_pixels_count_byte = 0;
 436                const uint16_t *raw_pixel_start = 0;
 437                const uint16_t *cmd_pixel_start, *cmd_pixel_end = 0;
 438
 439                prefetchw((void *) cmd); /* pull in one cache line at least */
 440
 441                *cmd++ = 0xAF;
 442                *cmd++ = 0x6B;
 443                *cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF);
 444                *cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF);
 445                *cmd++ = (uint8_t) ((dev_addr) & 0xFF);
 446
 447                cmd_pixels_count_byte = cmd++; /*  we'll know this later */
 448                cmd_pixel_start = pixel;
 449
 450                raw_pixels_count_byte = cmd++; /*  we'll know this later */
 451                raw_pixel_start = pixel;
 452
 453                cmd_pixel_end = pixel + min(MAX_CMD_PIXELS + 1,
 454                        min((int)(pixel_end - pixel),
 455                            (int)(cmd_buffer_end - cmd) / bpp));
 456
 457                prefetch_range((void *) pixel, (cmd_pixel_end - pixel) * bpp);
 458
 459                while (pixel < cmd_pixel_end) {
 460                        const uint16_t * const repeating_pixel = pixel;
 461
 462                        *(uint16_t *)cmd = cpu_to_be16p(pixel);
 463                        cmd += 2;
 464                        pixel++;
 465
 466                        if (unlikely((pixel < cmd_pixel_end) &&
 467                                     (*pixel == *repeating_pixel))) {
 468                                /* go back and fill in raw pixel count */
 469                                *raw_pixels_count_byte = ((repeating_pixel -
 470                                                raw_pixel_start) + 1) & 0xFF;
 471
 472                                while ((pixel < cmd_pixel_end)
 473                                       && (*pixel == *repeating_pixel)) {
 474                                        pixel++;
 475                                }
 476
 477                                /* immediately after raw data is repeat byte */
 478                                *cmd++ = ((pixel - repeating_pixel) - 1) & 0xFF;
 479
 480                                /* Then start another raw pixel span */
 481                                raw_pixel_start = pixel;
 482                                raw_pixels_count_byte = cmd++;
 483                        }
 484                }
 485
 486                if (pixel > raw_pixel_start) {
 487                        /* finalize last RAW span */
 488                        *raw_pixels_count_byte = (pixel-raw_pixel_start) & 0xFF;
 489                }
 490
 491                *cmd_pixels_count_byte = (pixel - cmd_pixel_start) & 0xFF;
 492                dev_addr += (pixel - cmd_pixel_start) * bpp;
 493        }
 494
 495        if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) {
 496                /* Fill leftover bytes with no-ops */
 497                if (cmd_buffer_end > cmd)
 498                        memset(cmd, 0xAF, cmd_buffer_end - cmd);
 499                cmd = (uint8_t *) cmd_buffer_end;
 500        }
 501
 502        *command_buffer_ptr = cmd;
 503        *pixel_start_ptr = pixel;
 504        *device_address_ptr = dev_addr;
 505
 506        return;
 507}
 508
 509/*
 510 * There are 3 copies of every pixel: The front buffer that the fbdev
 511 * client renders to, the actual framebuffer across the USB bus in hardware
 512 * (that we can only write to, slowly, and can never read), and (optionally)
 513 * our shadow copy that tracks what's been sent to that hardware buffer.
 514 */
 515static int dlfb_render_hline(struct dlfb_data *dev, struct urb **urb_ptr,
 516                              const char *front, char **urb_buf_ptr,
 517                              u32 byte_offset, u32 byte_width,
 518                              int *ident_ptr, int *sent_ptr)
 519{
 520        const u8 *line_start, *line_end, *next_pixel;
 521        u32 dev_addr = dev->base16 + byte_offset;
 522        struct urb *urb = *urb_ptr;
 523        u8 *cmd = *urb_buf_ptr;
 524        u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;
 525
 526        line_start = (u8 *) (front + byte_offset);
 527        next_pixel = line_start;
 528        line_end = next_pixel + byte_width;
 529
 530        if (dev->backing_buffer) {
 531                int offset;
 532                const u8 *back_start = (u8 *) (dev->backing_buffer
 533                                                + byte_offset);
 534
 535                *ident_ptr += dlfb_trim_hline(back_start, &next_pixel,
 536                        &byte_width);
 537
 538                offset = next_pixel - line_start;
 539                line_end = next_pixel + byte_width;
 540                dev_addr += offset;
 541                back_start += offset;
 542                line_start += offset;
 543
 544                memcpy((char *)back_start, (char *) line_start,
 545                       byte_width);
 546        }
 547
 548        while (next_pixel < line_end) {
 549
 550                dlfb_compress_hline((const uint16_t **) &next_pixel,
 551                             (const uint16_t *) line_end, &dev_addr,
 552                        (u8 **) &cmd, (u8 *) cmd_end);
 553
 554                if (cmd >= cmd_end) {
 555                        int len = cmd - (u8 *) urb->transfer_buffer;
 556                        if (dlfb_submit_urb(dev, urb, len))
 557                                return 1; /* lost pixels is set */
 558                        *sent_ptr += len;
 559                        urb = dlfb_get_urb(dev);
 560                        if (!urb)
 561                                return 1; /* lost_pixels is set */
 562                        *urb_ptr = urb;
 563                        cmd = urb->transfer_buffer;
 564                        cmd_end = &cmd[urb->transfer_buffer_length];
 565                }
 566        }
 567
 568        *urb_buf_ptr = cmd;
 569
 570        return 0;
 571}
 572
 573int dlfb_handle_damage(struct dlfb_data *dev, int x, int y,
 574               int width, int height, char *data)
 575{
 576        int i, ret;
 577        char *cmd;
 578        cycles_t start_cycles, end_cycles;
 579        int bytes_sent = 0;
 580        int bytes_identical = 0;
 581        struct urb *urb;
 582        int aligned_x;
 583
 584        start_cycles = get_cycles();
 585
 586        aligned_x = DL_ALIGN_DOWN(x, sizeof(unsigned long));
 587        width = DL_ALIGN_UP(width + (x-aligned_x), sizeof(unsigned long));
 588        x = aligned_x;
 589
 590        if ((width <= 0) ||
 591            (x + width > dev->info->var.xres) ||
 592            (y + height > dev->info->var.yres))
 593                return -EINVAL;
 594
 595        if (!atomic_read(&dev->usb_active))
 596                return 0;
 597
 598        urb = dlfb_get_urb(dev);
 599        if (!urb)
 600                return 0;
 601        cmd = urb->transfer_buffer;
 602
 603        for (i = y; i < y + height ; i++) {
 604                const int line_offset = dev->info->fix.line_length * i;
 605                const int byte_offset = line_offset + (x * BPP);
 606
 607                if (dlfb_render_hline(dev, &urb,
 608                                      (char *) dev->info->fix.smem_start,
 609                                      &cmd, byte_offset, width * BPP,
 610                                      &bytes_identical, &bytes_sent))
 611                        goto error;
 612        }
 613
 614        if (cmd > (char *) urb->transfer_buffer) {
 615                /* Send partial buffer remaining before exiting */
 616                int len = cmd - (char *) urb->transfer_buffer;
 617                ret = dlfb_submit_urb(dev, urb, len);
 618                bytes_sent += len;
 619        } else
 620                dlfb_urb_completion(urb);
 621
 622error:
 623        atomic_add(bytes_sent, &dev->bytes_sent);
 624        atomic_add(bytes_identical, &dev->bytes_identical);
 625        atomic_add(width*height*2, &dev->bytes_rendered);
 626        end_cycles = get_cycles();
 627        atomic_add(((unsigned int) ((end_cycles - start_cycles)
 628                    >> 10)), /* Kcycles */
 629                   &dev->cpu_kcycles_used);
 630
 631        return 0;
 632}
 633
 634/*
 635 * Path triggered by usermode clients who write to filesystem
 636 * e.g. cat filename > /dev/fb1
 637 * Not used by X Windows or text-mode console. But useful for testing.
 638 * Slow because of extra copy and we must assume all pixels dirty.
 639 */
 640static ssize_t dlfb_ops_write(struct fb_info *info, const char __user *buf,
 641                          size_t count, loff_t *ppos)
 642{
 643        ssize_t result;
 644        struct dlfb_data *dev = info->par;
 645        u32 offset = (u32) *ppos;
 646
 647        result = fb_sys_write(info, buf, count, ppos);
 648
 649        if (result > 0) {
 650                int start = max((int)(offset / info->fix.line_length) - 1, 0);
 651                int lines = min((u32)((result / info->fix.line_length) + 1),
 652                                (u32)info->var.yres);
 653
 654                dlfb_handle_damage(dev, 0, start, info->var.xres,
 655                        lines, info->screen_base);
 656        }
 657
 658        return result;
 659}
 660
 661/* hardware has native COPY command (see libdlo), but not worth it for fbcon */
 662static void dlfb_ops_copyarea(struct fb_info *info,
 663                                const struct fb_copyarea *area)
 664{
 665
 666        struct dlfb_data *dev = info->par;
 667
 668        sys_copyarea(info, area);
 669
 670        dlfb_handle_damage(dev, area->dx, area->dy,
 671                        area->width, area->height, info->screen_base);
 672}
 673
 674static void dlfb_ops_imageblit(struct fb_info *info,
 675                                const struct fb_image *image)
 676{
 677        struct dlfb_data *dev = info->par;
 678
 679        sys_imageblit(info, image);
 680
 681        dlfb_handle_damage(dev, image->dx, image->dy,
 682                        image->width, image->height, info->screen_base);
 683}
 684
 685static void dlfb_ops_fillrect(struct fb_info *info,
 686                          const struct fb_fillrect *rect)
 687{
 688        struct dlfb_data *dev = info->par;
 689
 690        sys_fillrect(info, rect);
 691
 692        dlfb_handle_damage(dev, rect->dx, rect->dy, rect->width,
 693                              rect->height, info->screen_base);
 694}
 695
 696/*
 697 * NOTE: fb_defio.c is holding info->fbdefio.mutex
 698 *   Touching ANY framebuffer memory that triggers a page fault
 699 *   in fb_defio will cause a deadlock, when it also tries to
 700 *   grab the same mutex.
 701 */
 702static void dlfb_dpy_deferred_io(struct fb_info *info,
 703                                struct list_head *pagelist)
 704{
 705        struct page *cur;
 706        struct fb_deferred_io *fbdefio = info->fbdefio;
 707        struct dlfb_data *dev = info->par;
 708        struct urb *urb;
 709        char *cmd;
 710        cycles_t start_cycles, end_cycles;
 711        int bytes_sent = 0;
 712        int bytes_identical = 0;
 713        int bytes_rendered = 0;
 714
 715        if (!fb_defio)
 716                return;
 717
 718        if (!atomic_read(&dev->usb_active))
 719                return;
 720
 721        start_cycles = get_cycles();
 722
 723        urb = dlfb_get_urb(dev);
 724        if (!urb)
 725                return;
 726
 727        cmd = urb->transfer_buffer;
 728
 729        /* walk the written page list and render each to device */
 730        list_for_each_entry(cur, &fbdefio->pagelist, lru) {
 731
 732                if (dlfb_render_hline(dev, &urb, (char *) info->fix.smem_start,
 733                                  &cmd, cur->index << PAGE_SHIFT,
 734                                  PAGE_SIZE, &bytes_identical, &bytes_sent))
 735                        goto error;
 736                bytes_rendered += PAGE_SIZE;
 737        }
 738
 739        if (cmd > (char *) urb->transfer_buffer) {
 740                /* Send partial buffer remaining before exiting */
 741                int len = cmd - (char *) urb->transfer_buffer;
 742                dlfb_submit_urb(dev, urb, len);
 743                bytes_sent += len;
 744        } else
 745                dlfb_urb_completion(urb);
 746
 747error:
 748        atomic_add(bytes_sent, &dev->bytes_sent);
 749        atomic_add(bytes_identical, &dev->bytes_identical);
 750        atomic_add(bytes_rendered, &dev->bytes_rendered);
 751        end_cycles = get_cycles();
 752        atomic_add(((unsigned int) ((end_cycles - start_cycles)
 753                    >> 10)), /* Kcycles */
 754                   &dev->cpu_kcycles_used);
 755}
 756
 757static int dlfb_get_edid(struct dlfb_data *dev, char *edid, int len)
 758{
 759        int i;
 760        int ret;
 761        char *rbuf;
 762
 763        rbuf = kmalloc(2, GFP_KERNEL);
 764        if (!rbuf)
 765                return 0;
 766
 767        for (i = 0; i < len; i++) {
 768                ret = usb_control_msg(dev->udev,
 769                                    usb_rcvctrlpipe(dev->udev, 0), (0x02),
 770                                    (0x80 | (0x02 << 5)), i << 8, 0xA1, rbuf, 2,
 771                                    HZ);
 772                if (ret < 1) {
 773                        pr_err("Read EDID byte %d failed err %x\n", i, ret);
 774                        i--;
 775                        break;
 776                }
 777                edid[i] = rbuf[1];
 778        }
 779
 780        kfree(rbuf);
 781
 782        return i;
 783}
 784
 785static int dlfb_ops_ioctl(struct fb_info *info, unsigned int cmd,
 786                                unsigned long arg)
 787{
 788
 789        struct dlfb_data *dev = info->par;
 790
 791        if (!atomic_read(&dev->usb_active))
 792                return 0;
 793
 794        /* TODO: Update X server to get this from sysfs instead */
 795        if (cmd == DLFB_IOCTL_RETURN_EDID) {
 796                void __user *edid = (void __user *)arg;
 797                if (copy_to_user(edid, dev->edid, dev->edid_size))
 798                        return -EFAULT;
 799                return 0;
 800        }
 801
 802        /* TODO: Help propose a standard fb.h ioctl to report mmap damage */
 803        if (cmd == DLFB_IOCTL_REPORT_DAMAGE) {
 804                struct dloarea area;
 805
 806                if (copy_from_user(&area, (void __user *)arg,
 807                                  sizeof(struct dloarea)))
 808                        return -EFAULT;
 809
 810                /*
 811                 * If we have a damage-aware client, turn fb_defio "off"
 812                 * To avoid perf imact of unnecessary page fault handling.
 813                 * Done by resetting the delay for this fb_info to a very
 814                 * long period. Pages will become writable and stay that way.
 815                 * Reset to normal value when all clients have closed this fb.
 816                 */
 817                if (info->fbdefio)
 818                        info->fbdefio->delay = DL_DEFIO_WRITE_DISABLE;
 819
 820                if (area.x < 0)
 821                        area.x = 0;
 822
 823                if (area.x > info->var.xres)
 824                        area.x = info->var.xres;
 825
 826                if (area.y < 0)
 827                        area.y = 0;
 828
 829                if (area.y > info->var.yres)
 830                        area.y = info->var.yres;
 831
 832                dlfb_handle_damage(dev, area.x, area.y, area.w, area.h,
 833                           info->screen_base);
 834        }
 835
 836        return 0;
 837}
 838
 839/* taken from vesafb */
 840static int
 841dlfb_ops_setcolreg(unsigned regno, unsigned red, unsigned green,
 842               unsigned blue, unsigned transp, struct fb_info *info)
 843{
 844        int err = 0;
 845
 846        if (regno >= info->cmap.len)
 847                return 1;
 848
 849        if (regno < 16) {
 850                if (info->var.red.offset == 10) {
 851                        /* 1:5:5:5 */
 852                        ((u32 *) (info->pseudo_palette))[regno] =
 853                            ((red & 0xf800) >> 1) |
 854                            ((green & 0xf800) >> 6) | ((blue & 0xf800) >> 11);
 855                } else {
 856                        /* 0:5:6:5 */
 857                        ((u32 *) (info->pseudo_palette))[regno] =
 858                            ((red & 0xf800)) |
 859                            ((green & 0xfc00) >> 5) | ((blue & 0xf800) >> 11);
 860                }
 861        }
 862
 863        return err;
 864}
 865
 866/*
 867 * It's common for several clients to have framebuffer open simultaneously.
 868 * e.g. both fbcon and X. Makes things interesting.
 869 * Assumes caller is holding info->lock (for open and release at least)
 870 */
 871static int dlfb_ops_open(struct fb_info *info, int user)
 872{
 873        struct dlfb_data *dev = info->par;
 874
 875        /*
 876         * fbcon aggressively connects to first framebuffer it finds,
 877         * preventing other clients (X) from working properly. Usually
 878         * not what the user wants. Fail by default with option to enable.
 879         */
 880        if ((user == 0) && (!console))
 881                return -EBUSY;
 882
 883        /* If the USB device is gone, we don't accept new opens */
 884        if (dev->virtualized)
 885                return -ENODEV;
 886
 887        dev->fb_count++;
 888
 889        kref_get(&dev->kref);
 890
 891        if (fb_defio && (info->fbdefio == NULL)) {
 892                /* enable defio at last moment if not disabled by client */
 893
 894                struct fb_deferred_io *fbdefio;
 895
 896                fbdefio = kzalloc(sizeof(struct fb_deferred_io), GFP_KERNEL);
 897
 898                if (fbdefio) {
 899                        fbdefio->delay = DL_DEFIO_WRITE_DELAY;
 900                        fbdefio->deferred_io = dlfb_dpy_deferred_io;
 901                }
 902
 903                info->fbdefio = fbdefio;
 904                fb_deferred_io_init(info);
 905        }
 906
 907        pr_notice("open /dev/fb%d user=%d fb_info=%p count=%d\n",
 908            info->node, user, info, dev->fb_count);
 909
 910        return 0;
 911}
 912
 913/*
 914 * Called when all client interfaces to start transactions have been disabled,
 915 * and all references to our device instance (dlfb_data) are released.
 916 * Every transaction must have a reference, so we know are fully spun down
 917 */
 918static void dlfb_free(struct kref *kref)
 919{
 920        struct dlfb_data *dev = container_of(kref, struct dlfb_data, kref);
 921
 922        if (dev->backing_buffer)
 923                vfree(dev->backing_buffer);
 924
 925        kfree(dev->edid);
 926
 927        pr_warn("freeing dlfb_data %p\n", dev);
 928
 929        kfree(dev);
 930}
 931
 932static void dlfb_release_urb_work(struct work_struct *work)
 933{
 934        struct urb_node *unode = container_of(work, struct urb_node,
 935                                              release_urb_work.work);
 936
 937        up(&unode->dev->urbs.limit_sem);
 938}
 939
 940static void dlfb_free_framebuffer(struct dlfb_data *dev)
 941{
 942        struct fb_info *info = dev->info;
 943
 944        if (info) {
 945                int node = info->node;
 946
 947                unregister_framebuffer(info);
 948
 949                if (info->cmap.len != 0)
 950                        fb_dealloc_cmap(&info->cmap);
 951                if (info->monspecs.modedb)
 952                        fb_destroy_modedb(info->monspecs.modedb);
 953                if (info->screen_base)
 954                        vfree(info->screen_base);
 955
 956                fb_destroy_modelist(&info->modelist);
 957
 958                dev->info = NULL;
 959
 960                /* Assume info structure is freed after this point */
 961                framebuffer_release(info);
 962
 963                pr_warn("fb_info for /dev/fb%d has been freed\n", node);
 964        }
 965
 966        /* ref taken in probe() as part of registering framebfufer */
 967        kref_put(&dev->kref, dlfb_free);
 968}
 969
 970static void dlfb_free_framebuffer_work(struct work_struct *work)
 971{
 972        struct dlfb_data *dev = container_of(work, struct dlfb_data,
 973                                             free_framebuffer_work.work);
 974        dlfb_free_framebuffer(dev);
 975}
 976/*
 977 * Assumes caller is holding info->lock mutex (for open and release at least)
 978 */
 979static int dlfb_ops_release(struct fb_info *info, int user)
 980{
 981        struct dlfb_data *dev = info->par;
 982
 983        dev->fb_count--;
 984
 985        /* We can't free fb_info here - fbmem will touch it when we return */
 986        if (dev->virtualized && (dev->fb_count == 0))
 987                schedule_delayed_work(&dev->free_framebuffer_work, HZ);
 988
 989        if ((dev->fb_count == 0) && (info->fbdefio)) {
 990                fb_deferred_io_cleanup(info);
 991                kfree(info->fbdefio);
 992                info->fbdefio = NULL;
 993                info->fbops->fb_mmap = dlfb_ops_mmap;
 994        }
 995
 996        pr_warn("released /dev/fb%d user=%d count=%d\n",
 997                  info->node, user, dev->fb_count);
 998
 999        kref_put(&dev->kref, dlfb_free);
1000
1001        return 0;
1002}
1003
1004/*
1005 * Check whether a video mode is supported by the DisplayLink chip
1006 * We start from monitor's modes, so don't need to filter that here
1007 */
1008static int dlfb_is_valid_mode(struct fb_videomode *mode,
1009                struct fb_info *info)
1010{
1011        struct dlfb_data *dev = info->par;
1012
1013        if (mode->xres * mode->yres > dev->sku_pixel_limit) {
1014                pr_warn("%dx%d beyond chip capabilities\n",
1015                       mode->xres, mode->yres);
1016                return 0;
1017        }
1018
1019        pr_info("%dx%d @ %d Hz valid mode\n", mode->xres, mode->yres,
1020                mode->refresh);
1021
1022        return 1;
1023}
1024
1025static void dlfb_var_color_format(struct fb_var_screeninfo *var)
1026{
1027        const struct fb_bitfield red = { 11, 5, 0 };
1028        const struct fb_bitfield green = { 5, 6, 0 };
1029        const struct fb_bitfield blue = { 0, 5, 0 };
1030
1031        var->bits_per_pixel = 16;
1032        var->red = red;
1033        var->green = green;
1034        var->blue = blue;
1035}
1036
1037static int dlfb_ops_check_var(struct fb_var_screeninfo *var,
1038                                struct fb_info *info)
1039{
1040        struct fb_videomode mode;
1041
1042        /* TODO: support dynamically changing framebuffer size */
1043        if ((var->xres * var->yres * 2) > info->fix.smem_len)
1044                return -EINVAL;
1045
1046        /* set device-specific elements of var unrelated to mode */
1047        dlfb_var_color_format(var);
1048
1049        fb_var_to_videomode(&mode, var);
1050
1051        if (!dlfb_is_valid_mode(&mode, info))
1052                return -EINVAL;
1053
1054        return 0;
1055}
1056
1057static int dlfb_ops_set_par(struct fb_info *info)
1058{
1059        struct dlfb_data *dev = info->par;
1060        int result;
1061        u16 *pix_framebuffer;
1062        int i;
1063
1064        pr_notice("set_par mode %dx%d\n", info->var.xres, info->var.yres);
1065
1066        result = dlfb_set_video_mode(dev, &info->var);
1067
1068        if ((result == 0) && (dev->fb_count == 0)) {
1069
1070                /* paint greenscreen */
1071
1072                pix_framebuffer = (u16 *) info->screen_base;
1073                for (i = 0; i < info->fix.smem_len / 2; i++)
1074                        pix_framebuffer[i] = 0x37e6;
1075
1076                dlfb_handle_damage(dev, 0, 0, info->var.xres, info->var.yres,
1077                                   info->screen_base);
1078        }
1079
1080        return result;
1081}
1082
1083/* To fonzi the jukebox (e.g. make blanking changes take effect) */
1084static char *dlfb_dummy_render(char *buf)
1085{
1086        *buf++ = 0xAF;
1087        *buf++ = 0x6A; /* copy */
1088        *buf++ = 0x00; /* from address*/
1089        *buf++ = 0x00;
1090        *buf++ = 0x00;
1091        *buf++ = 0x01; /* one pixel */
1092        *buf++ = 0x00; /* to address */
1093        *buf++ = 0x00;
1094        *buf++ = 0x00;
1095        return buf;
1096}
1097
1098/*
1099 * In order to come back from full DPMS off, we need to set the mode again
1100 */
1101static int dlfb_ops_blank(int blank_mode, struct fb_info *info)
1102{
1103        struct dlfb_data *dev = info->par;
1104        char *bufptr;
1105        struct urb *urb;
1106
1107        pr_info("/dev/fb%d FB_BLANK mode %d --> %d\n",
1108                info->node, dev->blank_mode, blank_mode);
1109
1110        if ((dev->blank_mode == FB_BLANK_POWERDOWN) &&
1111            (blank_mode != FB_BLANK_POWERDOWN)) {
1112
1113                /* returning from powerdown requires a fresh modeset */
1114                dlfb_set_video_mode(dev, &info->var);
1115        }
1116
1117        urb = dlfb_get_urb(dev);
1118        if (!urb)
1119                return 0;
1120
1121        bufptr = (char *) urb->transfer_buffer;
1122        bufptr = dlfb_vidreg_lock(bufptr);
1123        bufptr = dlfb_blanking(bufptr, blank_mode);
1124        bufptr = dlfb_vidreg_unlock(bufptr);
1125
1126        /* seems like a render op is needed to have blank change take effect */
1127        bufptr = dlfb_dummy_render(bufptr);
1128
1129        dlfb_submit_urb(dev, urb, bufptr -
1130                        (char *) urb->transfer_buffer);
1131
1132        dev->blank_mode = blank_mode;
1133
1134        return 0;
1135}
1136
1137static struct fb_ops dlfb_ops = {
1138        .owner = THIS_MODULE,
1139        .fb_read = fb_sys_read,
1140        .fb_write = dlfb_ops_write,
1141        .fb_setcolreg = dlfb_ops_setcolreg,
1142        .fb_fillrect = dlfb_ops_fillrect,
1143        .fb_copyarea = dlfb_ops_copyarea,
1144        .fb_imageblit = dlfb_ops_imageblit,
1145        .fb_mmap = dlfb_ops_mmap,
1146        .fb_ioctl = dlfb_ops_ioctl,
1147        .fb_open = dlfb_ops_open,
1148        .fb_release = dlfb_ops_release,
1149        .fb_blank = dlfb_ops_blank,
1150        .fb_check_var = dlfb_ops_check_var,
1151        .fb_set_par = dlfb_ops_set_par,
1152};
1153
1154
1155/*
1156 * Assumes &info->lock held by caller
1157 * Assumes no active clients have framebuffer open
1158 */
1159static int dlfb_realloc_framebuffer(struct dlfb_data *dev, struct fb_info *info)
1160{
1161        int retval = -ENOMEM;
1162        int old_len = info->fix.smem_len;
1163        int new_len;
1164        unsigned char *old_fb = info->screen_base;
1165        unsigned char *new_fb;
1166        unsigned char *new_back = 0;
1167
1168        pr_warn("Reallocating framebuffer. Addresses will change!\n");
1169
1170        new_len = info->fix.line_length * info->var.yres;
1171
1172        if (PAGE_ALIGN(new_len) > old_len) {
1173                /*
1174                 * Alloc system memory for virtual framebuffer
1175                 */
1176                new_fb = vmalloc(new_len);
1177                if (!new_fb) {
1178                        pr_err("Virtual framebuffer alloc failed\n");
1179                        goto error;
1180                }
1181
1182                if (info->screen_base) {
1183                        memcpy(new_fb, old_fb, old_len);
1184                        vfree(info->screen_base);
1185                }
1186
1187                info->screen_base = new_fb;
1188                info->fix.smem_len = PAGE_ALIGN(new_len);
1189                info->fix.smem_start = (unsigned long) new_fb;
1190                info->flags = udlfb_info_flags;
1191
1192                /*
1193                 * Second framebuffer copy to mirror the framebuffer state
1194                 * on the physical USB device. We can function without this.
1195                 * But with imperfect damage info we may send pixels over USB
1196                 * that were, in fact, unchanged - wasting limited USB bandwidth
1197                 */
1198                if (shadow)
1199                        new_back = vzalloc(new_len);
1200                if (!new_back)
1201                        pr_info("No shadow/backing buffer allocated\n");
1202                else {
1203                        if (dev->backing_buffer)
1204                                vfree(dev->backing_buffer);
1205                        dev->backing_buffer = new_back;
1206                }
1207        }
1208
1209        retval = 0;
1210
1211error:
1212        return retval;
1213}
1214
1215/*
1216 * 1) Get EDID from hw, or use sw default
1217 * 2) Parse into various fb_info structs
1218 * 3) Allocate virtual framebuffer memory to back highest res mode
1219 *
1220 * Parses EDID into three places used by various parts of fbdev:
1221 * fb_var_screeninfo contains the timing of the monitor's preferred mode
1222 * fb_info.monspecs is full parsed EDID info, including monspecs.modedb
1223 * fb_info.modelist is a linked list of all monitor & VESA modes which work
1224 *
1225 * If EDID is not readable/valid, then modelist is all VESA modes,
1226 * monspecs is NULL, and fb_var_screeninfo is set to safe VESA mode
1227 * Returns 0 if successful
1228 */
1229static int dlfb_setup_modes(struct dlfb_data *dev,
1230                           struct fb_info *info,
1231                           char *default_edid, size_t default_edid_size)
1232{
1233        int i;
1234        const struct fb_videomode *default_vmode = NULL;
1235        int result = 0;
1236        char *edid;
1237        int tries = 3;
1238
1239        if (info->dev) /* only use mutex if info has been registered */
1240                mutex_lock(&info->lock);
1241
1242        edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
1243        if (!edid) {
1244                result = -ENOMEM;
1245                goto error;
1246        }
1247
1248        fb_destroy_modelist(&info->modelist);
1249        memset(&info->monspecs, 0, sizeof(info->monspecs));
1250
1251        /*
1252         * Try to (re)read EDID from hardware first
1253         * EDID data may return, but not parse as valid
1254         * Try again a few times, in case of e.g. analog cable noise
1255         */
1256        while (tries--) {
1257
1258                i = dlfb_get_edid(dev, edid, EDID_LENGTH);
1259
1260                if (i >= EDID_LENGTH)
1261                        fb_edid_to_monspecs(edid, &info->monspecs);
1262
1263                if (info->monspecs.modedb_len > 0) {
1264                        dev->edid = edid;
1265                        dev->edid_size = i;
1266                        break;
1267                }
1268        }
1269
1270        /* If that fails, use a previously returned EDID if available */
1271        if (info->monspecs.modedb_len == 0) {
1272
1273                pr_err("Unable to get valid EDID from device/display\n");
1274
1275                if (dev->edid) {
1276                        fb_edid_to_monspecs(dev->edid, &info->monspecs);
1277                        if (info->monspecs.modedb_len > 0)
1278                                pr_err("Using previously queried EDID\n");
1279                }
1280        }
1281
1282        /* If that fails, use the default EDID we were handed */
1283        if (info->monspecs.modedb_len == 0) {
1284                if (default_edid_size >= EDID_LENGTH) {
1285                        fb_edid_to_monspecs(default_edid, &info->monspecs);
1286                        if (info->monspecs.modedb_len > 0) {
1287                                memcpy(edid, default_edid, default_edid_size);
1288                                dev->edid = edid;
1289                                dev->edid_size = default_edid_size;
1290                                pr_err("Using default/backup EDID\n");
1291                        }
1292                }
1293        }
1294
1295        /* If we've got modes, let's pick a best default mode */
1296        if (info->monspecs.modedb_len > 0) {
1297
1298                for (i = 0; i < info->monspecs.modedb_len; i++) {
1299                        if (dlfb_is_valid_mode(&info->monspecs.modedb[i], info))
1300                                fb_add_videomode(&info->monspecs.modedb[i],
1301                                        &info->modelist);
1302                        else {
1303                                if (i == 0)
1304                                        /* if we've removed top/best mode */
1305                                        info->monspecs.misc
1306                                                &= ~FB_MISC_1ST_DETAIL;
1307                        }
1308                }
1309
1310                default_vmode = fb_find_best_display(&info->monspecs,
1311                                                     &info->modelist);
1312        }
1313
1314        /* If everything else has failed, fall back to safe default mode */
1315        if (default_vmode == NULL) {
1316
1317                struct fb_videomode fb_vmode = {0};
1318
1319                /*
1320                 * Add the standard VESA modes to our modelist
1321                 * Since we don't have EDID, there may be modes that
1322                 * overspec monitor and/or are incorrect aspect ratio, etc.
1323                 * But at least the user has a chance to choose
1324                 */
1325                for (i = 0; i < VESA_MODEDB_SIZE; i++) {
1326                        if (dlfb_is_valid_mode((struct fb_videomode *)
1327                                                &vesa_modes[i], info))
1328                                fb_add_videomode(&vesa_modes[i],
1329                                                 &info->modelist);
1330                }
1331
1332                /*
1333                 * default to resolution safe for projectors
1334                 * (since they are most common case without EDID)
1335                 */
1336                fb_vmode.xres = 800;
1337                fb_vmode.yres = 600;
1338                fb_vmode.refresh = 60;
1339                default_vmode = fb_find_nearest_mode(&fb_vmode,
1340                                                     &info->modelist);
1341        }
1342
1343        /* If we have good mode and no active clients*/
1344        if ((default_vmode != NULL) && (dev->fb_count == 0)) {
1345
1346                fb_videomode_to_var(&info->var, default_vmode);
1347                dlfb_var_color_format(&info->var);
1348
1349                /*
1350                 * with mode size info, we can now alloc our framebuffer.
1351                 */
1352                memcpy(&info->fix, &dlfb_fix, sizeof(dlfb_fix));
1353                info->fix.line_length = info->var.xres *
1354                        (info->var.bits_per_pixel / 8);
1355
1356                result = dlfb_realloc_framebuffer(dev, info);
1357
1358        } else
1359                result = -EINVAL;
1360
1361error:
1362        if (edid && (dev->edid != edid))
1363                kfree(edid);
1364
1365        if (info->dev)
1366                mutex_unlock(&info->lock);
1367
1368        return result;
1369}
1370
1371static ssize_t metrics_bytes_rendered_show(struct device *fbdev,
1372                                   struct device_attribute *a, char *buf) {
1373        struct fb_info *fb_info = dev_get_drvdata(fbdev);
1374        struct dlfb_data *dev = fb_info->par;
1375        return snprintf(buf, PAGE_SIZE, "%u\n",
1376                        atomic_read(&dev->bytes_rendered));
1377}
1378
1379static ssize_t metrics_bytes_identical_show(struct device *fbdev,
1380                                   struct device_attribute *a, char *buf) {
1381        struct fb_info *fb_info = dev_get_drvdata(fbdev);
1382        struct dlfb_data *dev = fb_info->par;
1383        return snprintf(buf, PAGE_SIZE, "%u\n",
1384                        atomic_read(&dev->bytes_identical));
1385}
1386
1387static ssize_t metrics_bytes_sent_show(struct device *fbdev,
1388                                   struct device_attribute *a, char *buf) {
1389        struct fb_info *fb_info = dev_get_drvdata(fbdev);
1390        struct dlfb_data *dev = fb_info->par;
1391        return snprintf(buf, PAGE_SIZE, "%u\n",
1392                        atomic_read(&dev->bytes_sent));
1393}
1394
1395static ssize_t metrics_cpu_kcycles_used_show(struct device *fbdev,
1396                                   struct device_attribute *a, char *buf) {
1397        struct fb_info *fb_info = dev_get_drvdata(fbdev);
1398        struct dlfb_data *dev = fb_info->par;
1399        return snprintf(buf, PAGE_SIZE, "%u\n",
1400                        atomic_read(&dev->cpu_kcycles_used));
1401}
1402
1403static ssize_t edid_show(
1404                        struct file *filp,
1405                        struct kobject *kobj, struct bin_attribute *a,
1406                         char *buf, loff_t off, size_t count) {
1407        struct device *fbdev = container_of(kobj, struct device, kobj);
1408        struct fb_info *fb_info = dev_get_drvdata(fbdev);
1409        struct dlfb_data *dev = fb_info->par;
1410
1411        if (dev->edid == NULL)
1412                return 0;
1413
1414        if ((off >= dev->edid_size) || (count > dev->edid_size))
1415                return 0;
1416
1417        if (off + count > dev->edid_size)
1418                count = dev->edid_size - off;
1419
1420        pr_info("sysfs edid copy %p to %p, %d bytes\n",
1421                dev->edid, buf, (int) count);
1422
1423        memcpy(buf, dev->edid, count);
1424
1425        return count;
1426}
1427
1428static ssize_t edid_store(
1429                        struct file *filp,
1430                        struct kobject *kobj, struct bin_attribute *a,
1431                        char *src, loff_t src_off, size_t src_size) {
1432        struct device *fbdev = container_of(kobj, struct device, kobj);
1433        struct fb_info *fb_info = dev_get_drvdata(fbdev);
1434        struct dlfb_data *dev = fb_info->par;
1435        int ret;
1436
1437        /* We only support write of entire EDID at once, no offset*/
1438        if ((src_size != EDID_LENGTH) || (src_off != 0))
1439                return -EINVAL;
1440
1441        ret = dlfb_setup_modes(dev, fb_info, src, src_size);
1442        if (ret)
1443                return ret;
1444
1445        if (!dev->edid || memcmp(src, dev->edid, src_size))
1446                return -EINVAL;
1447
1448        pr_info("sysfs written EDID is new default\n");
1449        dlfb_ops_set_par(fb_info);
1450        return src_size;
1451}
1452
1453static ssize_t metrics_reset_store(struct device *fbdev,
1454                           struct device_attribute *attr,
1455                           const char *buf, size_t count)
1456{
1457        struct fb_info *fb_info = dev_get_drvdata(fbdev);
1458        struct dlfb_data *dev = fb_info->par;
1459
1460        atomic_set(&dev->bytes_rendered, 0);
1461        atomic_set(&dev->bytes_identical, 0);
1462        atomic_set(&dev->bytes_sent, 0);
1463        atomic_set(&dev->cpu_kcycles_used, 0);
1464
1465        return count;
1466}
1467
1468static struct bin_attribute edid_attr = {
1469        .attr.name = "edid",
1470        .attr.mode = 0666,
1471        .size = EDID_LENGTH,
1472        .read = edid_show,
1473        .write = edid_store
1474};
1475
1476static struct device_attribute fb_device_attrs[] = {
1477        __ATTR_RO(metrics_bytes_rendered),
1478        __ATTR_RO(metrics_bytes_identical),
1479        __ATTR_RO(metrics_bytes_sent),
1480        __ATTR_RO(metrics_cpu_kcycles_used),
1481        __ATTR(metrics_reset, S_IWUSR, NULL, metrics_reset_store),
1482};
1483
1484/*
1485 * This is necessary before we can communicate with the display controller.
1486 */
1487static int dlfb_select_std_channel(struct dlfb_data *dev)
1488{
1489        int ret;
1490        u8 set_def_chn[] = {       0x57, 0xCD, 0xDC, 0xA7,
1491                                0x1C, 0x88, 0x5E, 0x15,
1492                                0x60, 0xFE, 0xC6, 0x97,
1493                                0x16, 0x3D, 0x47, 0xF2  };
1494
1495        ret = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
1496                        NR_USB_REQUEST_CHANNEL,
1497                        (USB_DIR_OUT | USB_TYPE_VENDOR), 0, 0,
1498                        set_def_chn, sizeof(set_def_chn), USB_CTRL_SET_TIMEOUT);
1499        return ret;
1500}
1501
1502static int dlfb_parse_vendor_descriptor(struct dlfb_data *dev,
1503                                        struct usb_interface *interface)
1504{
1505        char *desc;
1506        char *buf;
1507        char *desc_end;
1508
1509        int total_len = 0;
1510
1511        buf = kzalloc(MAX_VENDOR_DESCRIPTOR_SIZE, GFP_KERNEL);
1512        if (!buf)
1513                return false;
1514        desc = buf;
1515
1516        total_len = usb_get_descriptor(interface_to_usbdev(interface),
1517                                        0x5f, /* vendor specific */
1518                                        0, desc, MAX_VENDOR_DESCRIPTOR_SIZE);
1519
1520        /* if not found, look in configuration descriptor */
1521        if (total_len < 0) {
1522                if (0 == usb_get_extra_descriptor(interface->cur_altsetting,
1523                        0x5f, &desc))
1524                        total_len = (int) desc[0];
1525        }
1526
1527        if (total_len > 5) {
1528                pr_info("vendor descriptor length:%x data:%02x %02x %02x %02x" \
1529                        "%02x %02x %02x %02x %02x %02x %02x\n",
1530                        total_len, desc[0],
1531                        desc[1], desc[2], desc[3], desc[4], desc[5], desc[6],
1532                        desc[7], desc[8], desc[9], desc[10]);
1533
1534                if ((desc[0] != total_len) || /* descriptor length */
1535                    (desc[1] != 0x5f) ||   /* vendor descriptor type */
1536                    (desc[2] != 0x01) ||   /* version (2 bytes) */
1537                    (desc[3] != 0x00) ||
1538                    (desc[4] != total_len - 2)) /* length after type */
1539                        goto unrecognized;
1540
1541                desc_end = desc + total_len;
1542                desc += 5; /* the fixed header we've already parsed */
1543
1544                while (desc < desc_end) {
1545                        u8 length;
1546                        u16 key;
1547
1548                        key = le16_to_cpu(*((u16 *) desc));
1549                        desc += sizeof(u16);
1550                        length = *desc;
1551                        desc++;
1552
1553                        switch (key) {
1554                        case 0x0200: { /* max_area */
1555                                u32 max_area;
1556                                max_area = le32_to_cpu(*((u32 *)desc));
1557                                pr_warn("DL chip limited to %d pixel modes\n",
1558                                        max_area);
1559                                dev->sku_pixel_limit = max_area;
1560                                break;
1561                        }
1562                        default:
1563                                break;
1564                        }
1565                        desc += length;
1566                }
1567        } else {
1568                pr_info("vendor descriptor not available (%d)\n", total_len);
1569        }
1570
1571        goto success;
1572
1573unrecognized:
1574        /* allow udlfb to load for now even if firmware unrecognized */
1575        pr_err("Unrecognized vendor firmware descriptor\n");
1576
1577success:
1578        kfree(buf);
1579        return true;
1580}
1581
1582static void dlfb_init_framebuffer_work(struct work_struct *work);
1583
1584static int dlfb_usb_probe(struct usb_interface *interface,
1585                        const struct usb_device_id *id)
1586{
1587        struct usb_device *usbdev;
1588        struct dlfb_data *dev = 0;
1589        int retval = -ENOMEM;
1590
1591        /* usb initialization */
1592
1593        usbdev = interface_to_usbdev(interface);
1594
1595        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
1596        if (dev == NULL) {
1597                dev_err(&interface->dev, "dlfb_usb_probe: failed alloc of dev struct\n");
1598                goto error;
1599        }
1600
1601        kref_init(&dev->kref); /* matching kref_put in usb .disconnect fn */
1602
1603        dev->udev = usbdev;
1604        dev->gdev = &usbdev->dev; /* our generic struct device * */
1605        usb_set_intfdata(interface, dev);
1606
1607        pr_info("%s %s - serial #%s\n",
1608                usbdev->manufacturer, usbdev->product, usbdev->serial);
1609        pr_info("vid_%04x&pid_%04x&rev_%04x driver's dlfb_data struct at %p\n",
1610                usbdev->descriptor.idVendor, usbdev->descriptor.idProduct,
1611                usbdev->descriptor.bcdDevice, dev);
1612        pr_info("console enable=%d\n", console);
1613        pr_info("fb_defio enable=%d\n", fb_defio);
1614        pr_info("shadow enable=%d\n", shadow);
1615
1616        dev->sku_pixel_limit = 2048 * 1152; /* default to maximum */
1617
1618        if (!dlfb_parse_vendor_descriptor(dev, interface)) {
1619                pr_err("firmware not recognized. Assume incompatible device\n");
1620                goto error;
1621        }
1622
1623        if (pixel_limit) {
1624                pr_warn("DL chip limit of %d overriden"
1625                        " by module param to %d\n",
1626                        dev->sku_pixel_limit, pixel_limit);
1627                dev->sku_pixel_limit = pixel_limit;
1628        }
1629
1630
1631        if (!dlfb_alloc_urb_list(dev, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
1632                retval = -ENOMEM;
1633                pr_err("dlfb_alloc_urb_list failed\n");
1634                goto error;
1635        }
1636
1637        kref_get(&dev->kref); /* matching kref_put in free_framebuffer_work */
1638
1639        /* We don't register a new USB class. Our client interface is fbdev */
1640
1641        /* Workitem keep things fast & simple during USB enumeration */
1642        INIT_DELAYED_WORK(&dev->init_framebuffer_work,
1643                          dlfb_init_framebuffer_work);
1644        schedule_delayed_work(&dev->init_framebuffer_work, 0);
1645
1646        return 0;
1647
1648error:
1649        if (dev) {
1650
1651                kref_put(&dev->kref, dlfb_free); /* ref for framebuffer */
1652                kref_put(&dev->kref, dlfb_free); /* last ref from kref_init */
1653
1654                /* dev has been deallocated. Do not dereference */
1655        }
1656
1657        return retval;
1658}
1659
1660static void dlfb_init_framebuffer_work(struct work_struct *work)
1661{
1662        struct dlfb_data *dev = container_of(work, struct dlfb_data,
1663                                             init_framebuffer_work.work);
1664        struct fb_info *info;
1665        int retval;
1666        int i;
1667
1668        /* allocates framebuffer driver structure, not framebuffer memory */
1669        info = framebuffer_alloc(0, dev->gdev);
1670        if (!info) {
1671                retval = -ENOMEM;
1672                pr_err("framebuffer_alloc failed\n");
1673                goto error;
1674        }
1675
1676        dev->info = info;
1677        info->par = dev;
1678        info->pseudo_palette = dev->pseudo_palette;
1679        info->fbops = &dlfb_ops;
1680
1681        retval = fb_alloc_cmap(&info->cmap, 256, 0);
1682        if (retval < 0) {
1683                pr_err("fb_alloc_cmap failed %x\n", retval);
1684                goto error;
1685        }
1686
1687        INIT_DELAYED_WORK(&dev->free_framebuffer_work,
1688                          dlfb_free_framebuffer_work);
1689
1690        INIT_LIST_HEAD(&info->modelist);
1691
1692        retval = dlfb_setup_modes(dev, info, NULL, 0);
1693        if (retval != 0) {
1694                pr_err("unable to find common mode for display and adapter\n");
1695                goto error;
1696        }
1697
1698        /* ready to begin using device */
1699
1700        atomic_set(&dev->usb_active, 1);
1701        dlfb_select_std_channel(dev);
1702
1703        dlfb_ops_check_var(&info->var, info);
1704        dlfb_ops_set_par(info);
1705
1706        retval = register_framebuffer(info);
1707        if (retval < 0) {
1708                pr_err("register_framebuffer failed %d\n", retval);
1709                goto error;
1710        }
1711
1712        for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++) {
1713                retval = device_create_file(info->dev, &fb_device_attrs[i]);
1714                if (retval) {
1715                        pr_warn("device_create_file failed %d\n", retval);
1716                }
1717        }
1718
1719        retval = device_create_bin_file(info->dev, &edid_attr);
1720        if (retval) {
1721                pr_warn("device_create_bin_file failed %d\n", retval);
1722        }
1723
1724        pr_info("DisplayLink USB device /dev/fb%d attached. %dx%d resolution."
1725                        " Using %dK framebuffer memory\n", info->node,
1726                        info->var.xres, info->var.yres,
1727                        ((dev->backing_buffer) ?
1728                        info->fix.smem_len * 2 : info->fix.smem_len) >> 10);
1729        return;
1730
1731error:
1732        dlfb_free_framebuffer(dev);
1733}
1734
1735static void dlfb_usb_disconnect(struct usb_interface *interface)
1736{
1737        struct dlfb_data *dev;
1738        struct fb_info *info;
1739        int i;
1740
1741        dev = usb_get_intfdata(interface);
1742        info = dev->info;
1743
1744        pr_info("USB disconnect starting\n");
1745
1746        /* we virtualize until all fb clients release. Then we free */
1747        dev->virtualized = true;
1748
1749        /* When non-active we'll update virtual framebuffer, but no new urbs */
1750        atomic_set(&dev->usb_active, 0);
1751
1752        /* this function will wait for all in-flight urbs to complete */
1753        dlfb_free_urb_list(dev);
1754
1755        if (info) {
1756                /* remove udlfb's sysfs interfaces */
1757                for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
1758                        device_remove_file(info->dev, &fb_device_attrs[i]);
1759                device_remove_bin_file(info->dev, &edid_attr);
1760                unlink_framebuffer(info);
1761        }
1762
1763        usb_set_intfdata(interface, NULL);
1764        dev->udev = NULL;
1765        dev->gdev = NULL;
1766
1767        /* if clients still have us open, will be freed on last close */
1768        if (dev->fb_count == 0)
1769                schedule_delayed_work(&dev->free_framebuffer_work, 0);
1770
1771        /* release reference taken by kref_init in probe() */
1772        kref_put(&dev->kref, dlfb_free);
1773
1774        /* consider dlfb_data freed */
1775
1776        return;
1777}
1778
1779static struct usb_driver dlfb_driver = {
1780        .name = "udlfb",
1781        .probe = dlfb_usb_probe,
1782        .disconnect = dlfb_usb_disconnect,
1783        .id_table = id_table,
1784};
1785
1786module_usb_driver(dlfb_driver);
1787
1788static void dlfb_urb_completion(struct urb *urb)
1789{
1790        struct urb_node *unode = urb->context;
1791        struct dlfb_data *dev = unode->dev;
1792        unsigned long flags;
1793
1794        /* sync/async unlink faults aren't errors */
1795        if (urb->status) {
1796                if (!(urb->status == -ENOENT ||
1797                    urb->status == -ECONNRESET ||
1798                    urb->status == -ESHUTDOWN)) {
1799                        pr_err("%s - nonzero write bulk status received: %d\n",
1800                                __func__, urb->status);
1801                        atomic_set(&dev->lost_pixels, 1);
1802                }
1803        }
1804
1805        urb->transfer_buffer_length = dev->urbs.size; /* reset to actual */
1806
1807        spin_lock_irqsave(&dev->urbs.lock, flags);
1808        list_add_tail(&unode->entry, &dev->urbs.list);
1809        dev->urbs.available++;
1810        spin_unlock_irqrestore(&dev->urbs.lock, flags);
1811
1812        /*
1813         * When using fb_defio, we deadlock if up() is called
1814         * while another is waiting. So queue to another process.
1815         */
1816        if (fb_defio)
1817                schedule_delayed_work(&unode->release_urb_work, 0);
1818        else
1819                up(&dev->urbs.limit_sem);
1820}
1821
1822static void dlfb_free_urb_list(struct dlfb_data *dev)
1823{
1824        int count = dev->urbs.count;
1825        struct list_head *node;
1826        struct urb_node *unode;
1827        struct urb *urb;
1828        int ret;
1829        unsigned long flags;
1830
1831        pr_notice("Freeing all render urbs\n");
1832
1833        /* keep waiting and freeing, until we've got 'em all */
1834        while (count--) {
1835
1836                /* Getting interrupted means a leak, but ok at disconnect */
1837                ret = down_interruptible(&dev->urbs.limit_sem);
1838                if (ret)
1839                        break;
1840
1841                spin_lock_irqsave(&dev->urbs.lock, flags);
1842
1843                node = dev->urbs.list.next; /* have reserved one with sem */
1844                list_del_init(node);
1845
1846                spin_unlock_irqrestore(&dev->urbs.lock, flags);
1847
1848                unode = list_entry(node, struct urb_node, entry);
1849                urb = unode->urb;
1850
1851                /* Free each separately allocated piece */
1852                usb_free_coherent(urb->dev, dev->urbs.size,
1853                                  urb->transfer_buffer, urb->transfer_dma);
1854                usb_free_urb(urb);
1855                kfree(node);
1856        }
1857
1858        dev->urbs.count = 0;
1859}
1860
1861static int dlfb_alloc_urb_list(struct dlfb_data *dev, int count, size_t size)
1862{
1863        int i = 0;
1864        struct urb *urb;
1865        struct urb_node *unode;
1866        char *buf;
1867
1868        spin_lock_init(&dev->urbs.lock);
1869
1870        dev->urbs.size = size;
1871        INIT_LIST_HEAD(&dev->urbs.list);
1872
1873        while (i < count) {
1874                unode = kzalloc(sizeof(struct urb_node), GFP_KERNEL);
1875                if (!unode)
1876                        break;
1877                unode->dev = dev;
1878
1879                INIT_DELAYED_WORK(&unode->release_urb_work,
1880                          dlfb_release_urb_work);
1881
1882                urb = usb_alloc_urb(0, GFP_KERNEL);
1883                if (!urb) {
1884                        kfree(unode);
1885                        break;
1886                }
1887                unode->urb = urb;
1888
1889                buf = usb_alloc_coherent(dev->udev, MAX_TRANSFER, GFP_KERNEL,
1890                                         &urb->transfer_dma);
1891                if (!buf) {
1892                        kfree(unode);
1893                        usb_free_urb(urb);
1894                        break;
1895                }
1896
1897                /* urb->transfer_buffer_length set to actual before submit */
1898                usb_fill_bulk_urb(urb, dev->udev, usb_sndbulkpipe(dev->udev, 1),
1899                        buf, size, dlfb_urb_completion, unode);
1900                urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
1901
1902                list_add_tail(&unode->entry, &dev->urbs.list);
1903
1904                i++;
1905        }
1906
1907        sema_init(&dev->urbs.limit_sem, i);
1908        dev->urbs.count = i;
1909        dev->urbs.available = i;
1910
1911        pr_notice("allocated %d %d byte urbs\n", i, (int) size);
1912
1913        return i;
1914}
1915
1916static struct urb *dlfb_get_urb(struct dlfb_data *dev)
1917{
1918        int ret = 0;
1919        struct list_head *entry;
1920        struct urb_node *unode;
1921        struct urb *urb = NULL;
1922        unsigned long flags;
1923
1924        /* Wait for an in-flight buffer to complete and get re-queued */
1925        ret = down_timeout(&dev->urbs.limit_sem, GET_URB_TIMEOUT);
1926        if (ret) {
1927                atomic_set(&dev->lost_pixels, 1);
1928                pr_warn("wait for urb interrupted: %x available: %d\n",
1929                       ret, dev->urbs.available);
1930                goto error;
1931        }
1932
1933        spin_lock_irqsave(&dev->urbs.lock, flags);
1934
1935        BUG_ON(list_empty(&dev->urbs.list)); /* reserved one with limit_sem */
1936        entry = dev->urbs.list.next;
1937        list_del_init(entry);
1938        dev->urbs.available--;
1939
1940        spin_unlock_irqrestore(&dev->urbs.lock, flags);
1941
1942        unode = list_entry(entry, struct urb_node, entry);
1943        urb = unode->urb;
1944
1945error:
1946        return urb;
1947}
1948
1949static int dlfb_submit_urb(struct dlfb_data *dev, struct urb *urb, size_t len)
1950{
1951        int ret;
1952
1953        BUG_ON(len > dev->urbs.size);
1954
1955        urb->transfer_buffer_length = len; /* set to actual payload len */
1956        ret = usb_submit_urb(urb, GFP_KERNEL);
1957        if (ret) {
1958                dlfb_urb_completion(urb); /* because no one else will */
1959                atomic_set(&dev->lost_pixels, 1);
1960                pr_err("usb_submit_urb error %x\n", ret);
1961        }
1962        return ret;
1963}
1964
1965module_param(console, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1966MODULE_PARM_DESC(console, "Allow fbcon to open framebuffer");
1967
1968module_param(fb_defio, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1969MODULE_PARM_DESC(fb_defio, "Page fault detection of mmap writes");
1970
1971module_param(shadow, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1972MODULE_PARM_DESC(shadow, "Shadow vid mem. Disable to save mem but lose perf");
1973
1974module_param(pixel_limit, int, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1975MODULE_PARM_DESC(pixel_limit, "Force limit on max mode (in x*y pixels)");
1976
1977MODULE_AUTHOR("Roberto De Ioris <roberto@unbit.it>, "
1978              "Jaya Kumar <jayakumar.lkml@gmail.com>, "
1979              "Bernie Thompson <bernie@plugable.com>");
1980MODULE_DESCRIPTION("DisplayLink kernel framebuffer driver");
1981MODULE_LICENSE("GPL");
1982
1983
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