linux/drivers/parisc/pdc_stable.c
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   1/* 
   2 *    Interfaces to retrieve and set PDC Stable options (firmware)
   3 *
   4 *    Copyright (C) 2005-2006 Thibaut VARENE <varenet@parisc-linux.org>
   5 *
   6 *    This program is free software; you can redistribute it and/or modify
   7 *    it under the terms of the GNU General Public License, version 2, as
   8 *    published by the Free Software Foundation.
   9 *
  10 *    This program is distributed in the hope that it will be useful,
  11 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 *    GNU General Public License for more details.
  14 *
  15 *    You should have received a copy of the GNU General Public License
  16 *    along with this program; if not, write to the Free Software
  17 *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18 *
  19 *
  20 *    DEV NOTE: the PDC Procedures reference states that:
  21 *    "A minimum of 96 bytes of Stable Storage is required. Providing more than
  22 *    96 bytes of Stable Storage is optional [...]. Failure to provide the
  23 *    optional locations from 96 to 192 results in the loss of certain
  24 *    functionality during boot."
  25 *
  26 *    Since locations between 96 and 192 are the various paths, most (if not
  27 *    all) PA-RISC machines should have them. Anyway, for safety reasons, the
  28 *    following code can deal with just 96 bytes of Stable Storage, and all
  29 *    sizes between 96 and 192 bytes (provided they are multiple of struct
  30 *    device_path size, eg: 128, 160 and 192) to provide full information.
  31 *    One last word: there's one path we can always count on: the primary path.
  32 *    Anything above 224 bytes is used for 'osdep2' OS-dependent storage area.
  33 *
  34 *    The first OS-dependent area should always be available. Obviously, this is
  35 *    not true for the other one. Also bear in mind that reading/writing from/to
  36 *    osdep2 is much more expensive than from/to osdep1.
  37 *    NOTE: We do not handle the 2 bytes OS-dep area at 0x5D, nor the first
  38 *    2 bytes of storage available right after OSID. That's a total of 4 bytes
  39 *    sacrificed: -ETOOLAZY :P
  40 *
  41 *    The current policy wrt file permissions is:
  42 *      - write: root only
  43 *      - read: (reading triggers PDC calls) ? root only : everyone
  44 *    The rationale is that PDC calls could hog (DoS) the machine.
  45 *
  46 *      TODO:
  47 *      - timer/fastsize write calls
  48 */
  49
  50#undef PDCS_DEBUG
  51#ifdef PDCS_DEBUG
  52#define DPRINTK(fmt, args...)   printk(KERN_DEBUG fmt, ## args)
  53#else
  54#define DPRINTK(fmt, args...)
  55#endif
  56
  57#include <linux/module.h>
  58#include <linux/init.h>
  59#include <linux/kernel.h>
  60#include <linux/string.h>
  61#include <linux/capability.h>
  62#include <linux/ctype.h>
  63#include <linux/sysfs.h>
  64#include <linux/kobject.h>
  65#include <linux/device.h>
  66#include <linux/errno.h>
  67#include <linux/spinlock.h>
  68
  69#include <asm/pdc.h>
  70#include <asm/page.h>
  71#include <asm/uaccess.h>
  72#include <asm/hardware.h>
  73
  74#define PDCS_VERSION    "0.30"
  75#define PDCS_PREFIX     "PDC Stable Storage"
  76
  77#define PDCS_ADDR_PPRI  0x00
  78#define PDCS_ADDR_OSID  0x40
  79#define PDCS_ADDR_OSD1  0x48
  80#define PDCS_ADDR_DIAG  0x58
  81#define PDCS_ADDR_FSIZ  0x5C
  82#define PDCS_ADDR_PCON  0x60
  83#define PDCS_ADDR_PALT  0x80
  84#define PDCS_ADDR_PKBD  0xA0
  85#define PDCS_ADDR_OSD2  0xE0
  86
  87MODULE_AUTHOR("Thibaut VARENE <varenet@parisc-linux.org>");
  88MODULE_DESCRIPTION("sysfs interface to HP PDC Stable Storage data");
  89MODULE_LICENSE("GPL");
  90MODULE_VERSION(PDCS_VERSION);
  91
  92/* holds Stable Storage size. Initialized once and for all, no lock needed */
  93static unsigned long pdcs_size __read_mostly;
  94
  95/* holds OS ID. Initialized once and for all, hopefully to 0x0006 */
  96static u16 pdcs_osid __read_mostly;
  97
  98/* This struct defines what we need to deal with a parisc pdc path entry */
  99struct pdcspath_entry {
 100        rwlock_t rw_lock;               /* to protect path entry access */
 101        short ready;                    /* entry record is valid if != 0 */
 102        unsigned long addr;             /* entry address in stable storage */
 103        char *name;                     /* entry name */
 104        struct device_path devpath;     /* device path in parisc representation */
 105        struct device *dev;             /* corresponding device */
 106        struct kobject kobj;
 107};
 108
 109struct pdcspath_attribute {
 110        struct attribute attr;
 111        ssize_t (*show)(struct pdcspath_entry *entry, char *buf);
 112        ssize_t (*store)(struct pdcspath_entry *entry, const char *buf, size_t count);
 113};
 114
 115#define PDCSPATH_ENTRY(_addr, _name) \
 116struct pdcspath_entry pdcspath_entry_##_name = { \
 117        .ready = 0, \
 118        .addr = _addr, \
 119        .name = __stringify(_name), \
 120};
 121
 122#define PDCS_ATTR(_name, _mode, _show, _store) \
 123struct kobj_attribute pdcs_attr_##_name = { \
 124        .attr = {.name = __stringify(_name), .mode = _mode}, \
 125        .show = _show, \
 126        .store = _store, \
 127};
 128
 129#define PATHS_ATTR(_name, _mode, _show, _store) \
 130struct pdcspath_attribute paths_attr_##_name = { \
 131        .attr = {.name = __stringify(_name), .mode = _mode}, \
 132        .show = _show, \
 133        .store = _store, \
 134};
 135
 136#define to_pdcspath_attribute(_attr) container_of(_attr, struct pdcspath_attribute, attr)
 137#define to_pdcspath_entry(obj)  container_of(obj, struct pdcspath_entry, kobj)
 138
 139/**
 140 * pdcspath_fetch - This function populates the path entry structs.
 141 * @entry: A pointer to an allocated pdcspath_entry.
 142 * 
 143 * The general idea is that you don't read from the Stable Storage every time
 144 * you access the files provided by the facilities. We store a copy of the
 145 * content of the stable storage WRT various paths in these structs. We read
 146 * these structs when reading the files, and we will write to these structs when
 147 * writing to the files, and only then write them back to the Stable Storage.
 148 *
 149 * This function expects to be called with @entry->rw_lock write-hold.
 150 */
 151static int
 152pdcspath_fetch(struct pdcspath_entry *entry)
 153{
 154        struct device_path *devpath;
 155
 156        if (!entry)
 157                return -EINVAL;
 158
 159        devpath = &entry->devpath;
 160        
 161        DPRINTK("%s: fetch: 0x%p, 0x%p, addr: 0x%lx\n", __func__,
 162                        entry, devpath, entry->addr);
 163
 164        /* addr, devpath and count must be word aligned */
 165        if (pdc_stable_read(entry->addr, devpath, sizeof(*devpath)) != PDC_OK)
 166                return -EIO;
 167                
 168        /* Find the matching device.
 169           NOTE: hardware_path overlays with device_path, so the nice cast can
 170           be used */
 171        entry->dev = hwpath_to_device((struct hardware_path *)devpath);
 172
 173        entry->ready = 1;
 174        
 175        DPRINTK("%s: device: 0x%p\n", __func__, entry->dev);
 176        
 177        return 0;
 178}
 179
 180/**
 181 * pdcspath_store - This function writes a path to stable storage.
 182 * @entry: A pointer to an allocated pdcspath_entry.
 183 * 
 184 * It can be used in two ways: either by passing it a preset devpath struct
 185 * containing an already computed hardware path, or by passing it a device
 186 * pointer, from which it'll find out the corresponding hardware path.
 187 * For now we do not handle the case where there's an error in writing to the
 188 * Stable Storage area, so you'd better not mess up the data :P
 189 *
 190 * This function expects to be called with @entry->rw_lock write-hold.
 191 */
 192static void
 193pdcspath_store(struct pdcspath_entry *entry)
 194{
 195        struct device_path *devpath;
 196
 197        BUG_ON(!entry);
 198
 199        devpath = &entry->devpath;
 200        
 201        /* We expect the caller to set the ready flag to 0 if the hardware
 202           path struct provided is invalid, so that we know we have to fill it.
 203           First case, we don't have a preset hwpath... */
 204        if (!entry->ready) {
 205                /* ...but we have a device, map it */
 206                BUG_ON(!entry->dev);
 207                device_to_hwpath(entry->dev, (struct hardware_path *)devpath);
 208        }
 209        /* else, we expect the provided hwpath to be valid. */
 210        
 211        DPRINTK("%s: store: 0x%p, 0x%p, addr: 0x%lx\n", __func__,
 212                        entry, devpath, entry->addr);
 213
 214        /* addr, devpath and count must be word aligned */
 215        if (pdc_stable_write(entry->addr, devpath, sizeof(*devpath)) != PDC_OK)
 216                WARN(1, KERN_ERR "%s: an error occurred when writing to PDC.\n"
 217                                "It is likely that the Stable Storage data has been corrupted.\n"
 218                                "Please check it carefully upon next reboot.\n", __func__);
 219                
 220        /* kobject is already registered */
 221        entry->ready = 2;
 222        
 223        DPRINTK("%s: device: 0x%p\n", __func__, entry->dev);
 224}
 225
 226/**
 227 * pdcspath_hwpath_read - This function handles hardware path pretty printing.
 228 * @entry: An allocated and populated pdscpath_entry struct.
 229 * @buf: The output buffer to write to.
 230 * 
 231 * We will call this function to format the output of the hwpath attribute file.
 232 */
 233static ssize_t
 234pdcspath_hwpath_read(struct pdcspath_entry *entry, char *buf)
 235{
 236        char *out = buf;
 237        struct device_path *devpath;
 238        short i;
 239
 240        if (!entry || !buf)
 241                return -EINVAL;
 242
 243        read_lock(&entry->rw_lock);
 244        devpath = &entry->devpath;
 245        i = entry->ready;
 246        read_unlock(&entry->rw_lock);
 247
 248        if (!i) /* entry is not ready */
 249                return -ENODATA;
 250        
 251        for (i = 0; i < 6; i++) {
 252                if (devpath->bc[i] >= 128)
 253                        continue;
 254                out += sprintf(out, "%u/", (unsigned char)devpath->bc[i]);
 255        }
 256        out += sprintf(out, "%u\n", (unsigned char)devpath->mod);
 257        
 258        return out - buf;
 259}
 260
 261/**
 262 * pdcspath_hwpath_write - This function handles hardware path modifying.
 263 * @entry: An allocated and populated pdscpath_entry struct.
 264 * @buf: The input buffer to read from.
 265 * @count: The number of bytes to be read.
 266 * 
 267 * We will call this function to change the current hardware path.
 268 * Hardware paths are to be given '/'-delimited, without brackets.
 269 * We make sure that the provided path actually maps to an existing
 270 * device, BUT nothing would prevent some foolish user to set the path to some
 271 * PCI bridge or even a CPU...
 272 * A better work around would be to make sure we are at the end of a device tree
 273 * for instance, but it would be IMHO beyond the simple scope of that driver.
 274 * The aim is to provide a facility. Data correctness is left to userland.
 275 */
 276static ssize_t
 277pdcspath_hwpath_write(struct pdcspath_entry *entry, const char *buf, size_t count)
 278{
 279        struct hardware_path hwpath;
 280        unsigned short i;
 281        char in[count+1], *temp;
 282        struct device *dev;
 283        int ret;
 284
 285        if (!entry || !buf || !count)
 286                return -EINVAL;
 287
 288        /* We'll use a local copy of buf */
 289        memset(in, 0, count+1);
 290        strncpy(in, buf, count);
 291        
 292        /* Let's clean up the target. 0xff is a blank pattern */
 293        memset(&hwpath, 0xff, sizeof(hwpath));
 294        
 295        /* First, pick the mod field (the last one of the input string) */
 296        if (!(temp = strrchr(in, '/')))
 297                return -EINVAL;
 298                        
 299        hwpath.mod = simple_strtoul(temp+1, NULL, 10);
 300        in[temp-in] = '\0';     /* truncate the remaining string. just precaution */
 301        DPRINTK("%s: mod: %d\n", __func__, hwpath.mod);
 302        
 303        /* Then, loop for each delimiter, making sure we don't have too many.
 304           we write the bc fields in a down-top way. No matter what, we stop
 305           before writing the last field. If there are too many fields anyway,
 306           then the user is a moron and it'll be caught up later when we'll
 307           check the consistency of the given hwpath. */
 308        for (i=5; ((temp = strrchr(in, '/'))) && (temp-in > 0) && (likely(i)); i--) {
 309                hwpath.bc[i] = simple_strtoul(temp+1, NULL, 10);
 310                in[temp-in] = '\0';
 311                DPRINTK("%s: bc[%d]: %d\n", __func__, i, hwpath.bc[i]);
 312        }
 313        
 314        /* Store the final field */             
 315        hwpath.bc[i] = simple_strtoul(in, NULL, 10);
 316        DPRINTK("%s: bc[%d]: %d\n", __func__, i, hwpath.bc[i]);
 317        
 318        /* Now we check that the user isn't trying to lure us */
 319        if (!(dev = hwpath_to_device((struct hardware_path *)&hwpath))) {
 320                printk(KERN_WARNING "%s: attempt to set invalid \"%s\" "
 321                        "hardware path: %s\n", __func__, entry->name, buf);
 322                return -EINVAL;
 323        }
 324        
 325        /* So far so good, let's get in deep */
 326        write_lock(&entry->rw_lock);
 327        entry->ready = 0;
 328        entry->dev = dev;
 329        
 330        /* Now, dive in. Write back to the hardware */
 331        pdcspath_store(entry);
 332        
 333        /* Update the symlink to the real device */
 334        sysfs_remove_link(&entry->kobj, "device");
 335        ret = sysfs_create_link(&entry->kobj, &entry->dev->kobj, "device");
 336        WARN_ON(ret);
 337
 338        write_unlock(&entry->rw_lock);
 339        
 340        printk(KERN_INFO PDCS_PREFIX ": changed \"%s\" path to \"%s\"\n",
 341                entry->name, buf);
 342        
 343        return count;
 344}
 345
 346/**
 347 * pdcspath_layer_read - Extended layer (eg. SCSI ids) pretty printing.
 348 * @entry: An allocated and populated pdscpath_entry struct.
 349 * @buf: The output buffer to write to.
 350 * 
 351 * We will call this function to format the output of the layer attribute file.
 352 */
 353static ssize_t
 354pdcspath_layer_read(struct pdcspath_entry *entry, char *buf)
 355{
 356        char *out = buf;
 357        struct device_path *devpath;
 358        short i;
 359
 360        if (!entry || !buf)
 361                return -EINVAL;
 362        
 363        read_lock(&entry->rw_lock);
 364        devpath = &entry->devpath;
 365        i = entry->ready;
 366        read_unlock(&entry->rw_lock);
 367
 368        if (!i) /* entry is not ready */
 369                return -ENODATA;
 370        
 371        for (i = 0; i < 6 && devpath->layers[i]; i++)
 372                out += sprintf(out, "%u ", devpath->layers[i]);
 373
 374        out += sprintf(out, "\n");
 375        
 376        return out - buf;
 377}
 378
 379/**
 380 * pdcspath_layer_write - This function handles extended layer modifying.
 381 * @entry: An allocated and populated pdscpath_entry struct.
 382 * @buf: The input buffer to read from.
 383 * @count: The number of bytes to be read.
 384 * 
 385 * We will call this function to change the current layer value.
 386 * Layers are to be given '.'-delimited, without brackets.
 387 * XXX beware we are far less checky WRT input data provided than for hwpath.
 388 * Potential harm can be done, since there's no way to check the validity of
 389 * the layer fields.
 390 */
 391static ssize_t
 392pdcspath_layer_write(struct pdcspath_entry *entry, const char *buf, size_t count)
 393{
 394        unsigned int layers[6]; /* device-specific info (ctlr#, unit#, ...) */
 395        unsigned short i;
 396        char in[count+1], *temp;
 397
 398        if (!entry || !buf || !count)
 399                return -EINVAL;
 400
 401        /* We'll use a local copy of buf */
 402        memset(in, 0, count+1);
 403        strncpy(in, buf, count);
 404        
 405        /* Let's clean up the target. 0 is a blank pattern */
 406        memset(&layers, 0, sizeof(layers));
 407        
 408        /* First, pick the first layer */
 409        if (unlikely(!isdigit(*in)))
 410                return -EINVAL;
 411        layers[0] = simple_strtoul(in, NULL, 10);
 412        DPRINTK("%s: layer[0]: %d\n", __func__, layers[0]);
 413        
 414        temp = in;
 415        for (i=1; ((temp = strchr(temp, '.'))) && (likely(i<6)); i++) {
 416                if (unlikely(!isdigit(*(++temp))))
 417                        return -EINVAL;
 418                layers[i] = simple_strtoul(temp, NULL, 10);
 419                DPRINTK("%s: layer[%d]: %d\n", __func__, i, layers[i]);
 420        }
 421                
 422        /* So far so good, let's get in deep */
 423        write_lock(&entry->rw_lock);
 424        
 425        /* First, overwrite the current layers with the new ones, not touching
 426           the hardware path. */
 427        memcpy(&entry->devpath.layers, &layers, sizeof(layers));
 428        
 429        /* Now, dive in. Write back to the hardware */
 430        pdcspath_store(entry);
 431        write_unlock(&entry->rw_lock);
 432        
 433        printk(KERN_INFO PDCS_PREFIX ": changed \"%s\" layers to \"%s\"\n",
 434                entry->name, buf);
 435        
 436        return count;
 437}
 438
 439/**
 440 * pdcspath_attr_show - Generic read function call wrapper.
 441 * @kobj: The kobject to get info from.
 442 * @attr: The attribute looked upon.
 443 * @buf: The output buffer.
 444 */
 445static ssize_t
 446pdcspath_attr_show(struct kobject *kobj, struct attribute *attr, char *buf)
 447{
 448        struct pdcspath_entry *entry = to_pdcspath_entry(kobj);
 449        struct pdcspath_attribute *pdcs_attr = to_pdcspath_attribute(attr);
 450        ssize_t ret = 0;
 451
 452        if (pdcs_attr->show)
 453                ret = pdcs_attr->show(entry, buf);
 454
 455        return ret;
 456}
 457
 458/**
 459 * pdcspath_attr_store - Generic write function call wrapper.
 460 * @kobj: The kobject to write info to.
 461 * @attr: The attribute to be modified.
 462 * @buf: The input buffer.
 463 * @count: The size of the buffer.
 464 */
 465static ssize_t
 466pdcspath_attr_store(struct kobject *kobj, struct attribute *attr,
 467                        const char *buf, size_t count)
 468{
 469        struct pdcspath_entry *entry = to_pdcspath_entry(kobj);
 470        struct pdcspath_attribute *pdcs_attr = to_pdcspath_attribute(attr);
 471        ssize_t ret = 0;
 472
 473        if (!capable(CAP_SYS_ADMIN))
 474                return -EACCES;
 475
 476        if (pdcs_attr->store)
 477                ret = pdcs_attr->store(entry, buf, count);
 478
 479        return ret;
 480}
 481
 482static const struct sysfs_ops pdcspath_attr_ops = {
 483        .show = pdcspath_attr_show,
 484        .store = pdcspath_attr_store,
 485};
 486
 487/* These are the two attributes of any PDC path. */
 488static PATHS_ATTR(hwpath, 0644, pdcspath_hwpath_read, pdcspath_hwpath_write);
 489static PATHS_ATTR(layer, 0644, pdcspath_layer_read, pdcspath_layer_write);
 490
 491static struct attribute *paths_subsys_attrs[] = {
 492        &paths_attr_hwpath.attr,
 493        &paths_attr_layer.attr,
 494        NULL,
 495};
 496
 497/* Specific kobject type for our PDC paths */
 498static struct kobj_type ktype_pdcspath = {
 499        .sysfs_ops = &pdcspath_attr_ops,
 500        .default_attrs = paths_subsys_attrs,
 501};
 502
 503/* We hard define the 4 types of path we expect to find */
 504static PDCSPATH_ENTRY(PDCS_ADDR_PPRI, primary);
 505static PDCSPATH_ENTRY(PDCS_ADDR_PCON, console);
 506static PDCSPATH_ENTRY(PDCS_ADDR_PALT, alternative);
 507static PDCSPATH_ENTRY(PDCS_ADDR_PKBD, keyboard);
 508
 509/* An array containing all PDC paths we will deal with */
 510static struct pdcspath_entry *pdcspath_entries[] = {
 511        &pdcspath_entry_primary,
 512        &pdcspath_entry_alternative,
 513        &pdcspath_entry_console,
 514        &pdcspath_entry_keyboard,
 515        NULL,
 516};
 517
 518
 519/* For more insight of what's going on here, refer to PDC Procedures doc,
 520 * Section PDC_STABLE */
 521
 522/**
 523 * pdcs_size_read - Stable Storage size output.
 524 * @buf: The output buffer to write to.
 525 */
 526static ssize_t pdcs_size_read(struct kobject *kobj,
 527                              struct kobj_attribute *attr,
 528                              char *buf)
 529{
 530        char *out = buf;
 531
 532        if (!buf)
 533                return -EINVAL;
 534
 535        /* show the size of the stable storage */
 536        out += sprintf(out, "%ld\n", pdcs_size);
 537
 538        return out - buf;
 539}
 540
 541/**
 542 * pdcs_auto_read - Stable Storage autoboot/search flag output.
 543 * @buf: The output buffer to write to.
 544 * @knob: The PF_AUTOBOOT or PF_AUTOSEARCH flag
 545 */
 546static ssize_t pdcs_auto_read(struct kobject *kobj,
 547                              struct kobj_attribute *attr,
 548                              char *buf, int knob)
 549{
 550        char *out = buf;
 551        struct pdcspath_entry *pathentry;
 552
 553        if (!buf)
 554                return -EINVAL;
 555
 556        /* Current flags are stored in primary boot path entry */
 557        pathentry = &pdcspath_entry_primary;
 558
 559        read_lock(&pathentry->rw_lock);
 560        out += sprintf(out, "%s\n", (pathentry->devpath.flags & knob) ?
 561                                        "On" : "Off");
 562        read_unlock(&pathentry->rw_lock);
 563
 564        return out - buf;
 565}
 566
 567/**
 568 * pdcs_autoboot_read - Stable Storage autoboot flag output.
 569 * @buf: The output buffer to write to.
 570 */
 571static ssize_t pdcs_autoboot_read(struct kobject *kobj,
 572                                  struct kobj_attribute *attr, char *buf)
 573{
 574        return pdcs_auto_read(kobj, attr, buf, PF_AUTOBOOT);
 575}
 576
 577/**
 578 * pdcs_autosearch_read - Stable Storage autoboot flag output.
 579 * @buf: The output buffer to write to.
 580 */
 581static ssize_t pdcs_autosearch_read(struct kobject *kobj,
 582                                    struct kobj_attribute *attr, char *buf)
 583{
 584        return pdcs_auto_read(kobj, attr, buf, PF_AUTOSEARCH);
 585}
 586
 587/**
 588 * pdcs_timer_read - Stable Storage timer count output (in seconds).
 589 * @buf: The output buffer to write to.
 590 *
 591 * The value of the timer field correponds to a number of seconds in powers of 2.
 592 */
 593static ssize_t pdcs_timer_read(struct kobject *kobj,
 594                               struct kobj_attribute *attr, char *buf)
 595{
 596        char *out = buf;
 597        struct pdcspath_entry *pathentry;
 598
 599        if (!buf)
 600                return -EINVAL;
 601
 602        /* Current flags are stored in primary boot path entry */
 603        pathentry = &pdcspath_entry_primary;
 604
 605        /* print the timer value in seconds */
 606        read_lock(&pathentry->rw_lock);
 607        out += sprintf(out, "%u\n", (pathentry->devpath.flags & PF_TIMER) ?
 608                                (1 << (pathentry->devpath.flags & PF_TIMER)) : 0);
 609        read_unlock(&pathentry->rw_lock);
 610
 611        return out - buf;
 612}
 613
 614/**
 615 * pdcs_osid_read - Stable Storage OS ID register output.
 616 * @buf: The output buffer to write to.
 617 */
 618static ssize_t pdcs_osid_read(struct kobject *kobj,
 619                              struct kobj_attribute *attr, char *buf)
 620{
 621        char *out = buf;
 622
 623        if (!buf)
 624                return -EINVAL;
 625
 626        out += sprintf(out, "%s dependent data (0x%.4x)\n",
 627                os_id_to_string(pdcs_osid), pdcs_osid);
 628
 629        return out - buf;
 630}
 631
 632/**
 633 * pdcs_osdep1_read - Stable Storage OS-Dependent data area 1 output.
 634 * @buf: The output buffer to write to.
 635 *
 636 * This can hold 16 bytes of OS-Dependent data.
 637 */
 638static ssize_t pdcs_osdep1_read(struct kobject *kobj,
 639                                struct kobj_attribute *attr, char *buf)
 640{
 641        char *out = buf;
 642        u32 result[4];
 643
 644        if (!buf)
 645                return -EINVAL;
 646
 647        if (pdc_stable_read(PDCS_ADDR_OSD1, &result, sizeof(result)) != PDC_OK)
 648                return -EIO;
 649
 650        out += sprintf(out, "0x%.8x\n", result[0]);
 651        out += sprintf(out, "0x%.8x\n", result[1]);
 652        out += sprintf(out, "0x%.8x\n", result[2]);
 653        out += sprintf(out, "0x%.8x\n", result[3]);
 654
 655        return out - buf;
 656}
 657
 658/**
 659 * pdcs_diagnostic_read - Stable Storage Diagnostic register output.
 660 * @buf: The output buffer to write to.
 661 *
 662 * I have NFC how to interpret the content of that register ;-).
 663 */
 664static ssize_t pdcs_diagnostic_read(struct kobject *kobj,
 665                                    struct kobj_attribute *attr, char *buf)
 666{
 667        char *out = buf;
 668        u32 result;
 669
 670        if (!buf)
 671                return -EINVAL;
 672
 673        /* get diagnostic */
 674        if (pdc_stable_read(PDCS_ADDR_DIAG, &result, sizeof(result)) != PDC_OK)
 675                return -EIO;
 676
 677        out += sprintf(out, "0x%.4x\n", (result >> 16));
 678
 679        return out - buf;
 680}
 681
 682/**
 683 * pdcs_fastsize_read - Stable Storage FastSize register output.
 684 * @buf: The output buffer to write to.
 685 *
 686 * This register holds the amount of system RAM to be tested during boot sequence.
 687 */
 688static ssize_t pdcs_fastsize_read(struct kobject *kobj,
 689                                  struct kobj_attribute *attr, char *buf)
 690{
 691        char *out = buf;
 692        u32 result;
 693
 694        if (!buf)
 695                return -EINVAL;
 696
 697        /* get fast-size */
 698        if (pdc_stable_read(PDCS_ADDR_FSIZ, &result, sizeof(result)) != PDC_OK)
 699                return -EIO;
 700
 701        if ((result & 0x0F) < 0x0E)
 702                out += sprintf(out, "%d kB", (1<<(result & 0x0F))*256);
 703        else
 704                out += sprintf(out, "All");
 705        out += sprintf(out, "\n");
 706        
 707        return out - buf;
 708}
 709
 710/**
 711 * pdcs_osdep2_read - Stable Storage OS-Dependent data area 2 output.
 712 * @buf: The output buffer to write to.
 713 *
 714 * This can hold pdcs_size - 224 bytes of OS-Dependent data, when available.
 715 */
 716static ssize_t pdcs_osdep2_read(struct kobject *kobj,
 717                                struct kobj_attribute *attr, char *buf)
 718{
 719        char *out = buf;
 720        unsigned long size;
 721        unsigned short i;
 722        u32 result;
 723
 724        if (unlikely(pdcs_size <= 224))
 725                return -ENODATA;
 726
 727        size = pdcs_size - 224;
 728
 729        if (!buf)
 730                return -EINVAL;
 731
 732        for (i=0; i<size; i+=4) {
 733                if (unlikely(pdc_stable_read(PDCS_ADDR_OSD2 + i, &result,
 734                                        sizeof(result)) != PDC_OK))
 735                        return -EIO;
 736                out += sprintf(out, "0x%.8x\n", result);
 737        }
 738
 739        return out - buf;
 740}
 741
 742/**
 743 * pdcs_auto_write - This function handles autoboot/search flag modifying.
 744 * @buf: The input buffer to read from.
 745 * @count: The number of bytes to be read.
 746 * @knob: The PF_AUTOBOOT or PF_AUTOSEARCH flag
 747 * 
 748 * We will call this function to change the current autoboot flag.
 749 * We expect a precise syntax:
 750 *      \"n\" (n == 0 or 1) to toggle AutoBoot Off or On
 751 */
 752static ssize_t pdcs_auto_write(struct kobject *kobj,
 753                               struct kobj_attribute *attr, const char *buf,
 754                               size_t count, int knob)
 755{
 756        struct pdcspath_entry *pathentry;
 757        unsigned char flags;
 758        char in[count+1], *temp;
 759        char c;
 760
 761        if (!capable(CAP_SYS_ADMIN))
 762                return -EACCES;
 763
 764        if (!buf || !count)
 765                return -EINVAL;
 766
 767        /* We'll use a local copy of buf */
 768        memset(in, 0, count+1);
 769        strncpy(in, buf, count);
 770
 771        /* Current flags are stored in primary boot path entry */
 772        pathentry = &pdcspath_entry_primary;
 773        
 774        /* Be nice to the existing flag record */
 775        read_lock(&pathentry->rw_lock);
 776        flags = pathentry->devpath.flags;
 777        read_unlock(&pathentry->rw_lock);
 778        
 779        DPRINTK("%s: flags before: 0x%X\n", __func__, flags);
 780
 781        temp = skip_spaces(in);
 782
 783        c = *temp++ - '0';
 784        if ((c != 0) && (c != 1))
 785                goto parse_error;
 786        if (c == 0)
 787                flags &= ~knob;
 788        else
 789                flags |= knob;
 790        
 791        DPRINTK("%s: flags after: 0x%X\n", __func__, flags);
 792                
 793        /* So far so good, let's get in deep */
 794        write_lock(&pathentry->rw_lock);
 795        
 796        /* Change the path entry flags first */
 797        pathentry->devpath.flags = flags;
 798                
 799        /* Now, dive in. Write back to the hardware */
 800        pdcspath_store(pathentry);
 801        write_unlock(&pathentry->rw_lock);
 802        
 803        printk(KERN_INFO PDCS_PREFIX ": changed \"%s\" to \"%s\"\n",
 804                (knob & PF_AUTOBOOT) ? "autoboot" : "autosearch",
 805                (flags & knob) ? "On" : "Off");
 806        
 807        return count;
 808
 809parse_error:
 810        printk(KERN_WARNING "%s: Parse error: expect \"n\" (n == 0 or 1)\n", __func__);
 811        return -EINVAL;
 812}
 813
 814/**
 815 * pdcs_autoboot_write - This function handles autoboot flag modifying.
 816 * @buf: The input buffer to read from.
 817 * @count: The number of bytes to be read.
 818 *
 819 * We will call this function to change the current boot flags.
 820 * We expect a precise syntax:
 821 *      \"n\" (n == 0 or 1) to toggle AutoSearch Off or On
 822 */
 823static ssize_t pdcs_autoboot_write(struct kobject *kobj,
 824                                   struct kobj_attribute *attr,
 825                                   const char *buf, size_t count)
 826{
 827        return pdcs_auto_write(kobj, attr, buf, count, PF_AUTOBOOT);
 828}
 829
 830/**
 831 * pdcs_autosearch_write - This function handles autosearch flag modifying.
 832 * @buf: The input buffer to read from.
 833 * @count: The number of bytes to be read.
 834 *
 835 * We will call this function to change the current boot flags.
 836 * We expect a precise syntax:
 837 *      \"n\" (n == 0 or 1) to toggle AutoSearch Off or On
 838 */
 839static ssize_t pdcs_autosearch_write(struct kobject *kobj,
 840                                     struct kobj_attribute *attr,
 841                                     const char *buf, size_t count)
 842{
 843        return pdcs_auto_write(kobj, attr, buf, count, PF_AUTOSEARCH);
 844}
 845
 846/**
 847 * pdcs_osdep1_write - Stable Storage OS-Dependent data area 1 input.
 848 * @buf: The input buffer to read from.
 849 * @count: The number of bytes to be read.
 850 *
 851 * This can store 16 bytes of OS-Dependent data. We use a byte-by-byte
 852 * write approach. It's up to userspace to deal with it when constructing
 853 * its input buffer.
 854 */
 855static ssize_t pdcs_osdep1_write(struct kobject *kobj,
 856                                 struct kobj_attribute *attr,
 857                                 const char *buf, size_t count)
 858{
 859        u8 in[16];
 860
 861        if (!capable(CAP_SYS_ADMIN))
 862                return -EACCES;
 863
 864        if (!buf || !count)
 865                return -EINVAL;
 866
 867        if (unlikely(pdcs_osid != OS_ID_LINUX))
 868                return -EPERM;
 869
 870        if (count > 16)
 871                return -EMSGSIZE;
 872
 873        /* We'll use a local copy of buf */
 874        memset(in, 0, 16);
 875        memcpy(in, buf, count);
 876
 877        if (pdc_stable_write(PDCS_ADDR_OSD1, &in, sizeof(in)) != PDC_OK)
 878                return -EIO;
 879
 880        return count;
 881}
 882
 883/**
 884 * pdcs_osdep2_write - Stable Storage OS-Dependent data area 2 input.
 885 * @buf: The input buffer to read from.
 886 * @count: The number of bytes to be read.
 887 *
 888 * This can store pdcs_size - 224 bytes of OS-Dependent data. We use a
 889 * byte-by-byte write approach. It's up to userspace to deal with it when
 890 * constructing its input buffer.
 891 */
 892static ssize_t pdcs_osdep2_write(struct kobject *kobj,
 893                                 struct kobj_attribute *attr,
 894                                 const char *buf, size_t count)
 895{
 896        unsigned long size;
 897        unsigned short i;
 898        u8 in[4];
 899
 900        if (!capable(CAP_SYS_ADMIN))
 901                return -EACCES;
 902
 903        if (!buf || !count)
 904                return -EINVAL;
 905
 906        if (unlikely(pdcs_size <= 224))
 907                return -ENOSYS;
 908
 909        if (unlikely(pdcs_osid != OS_ID_LINUX))
 910                return -EPERM;
 911
 912        size = pdcs_size - 224;
 913
 914        if (count > size)
 915                return -EMSGSIZE;
 916
 917        /* We'll use a local copy of buf */
 918
 919        for (i=0; i<count; i+=4) {
 920                memset(in, 0, 4);
 921                memcpy(in, buf+i, (count-i < 4) ? count-i : 4);
 922                if (unlikely(pdc_stable_write(PDCS_ADDR_OSD2 + i, &in,
 923                                        sizeof(in)) != PDC_OK))
 924                        return -EIO;
 925        }
 926
 927        return count;
 928}
 929
 930/* The remaining attributes. */
 931static PDCS_ATTR(size, 0444, pdcs_size_read, NULL);
 932static PDCS_ATTR(autoboot, 0644, pdcs_autoboot_read, pdcs_autoboot_write);
 933static PDCS_ATTR(autosearch, 0644, pdcs_autosearch_read, pdcs_autosearch_write);
 934static PDCS_ATTR(timer, 0444, pdcs_timer_read, NULL);
 935static PDCS_ATTR(osid, 0444, pdcs_osid_read, NULL);
 936static PDCS_ATTR(osdep1, 0600, pdcs_osdep1_read, pdcs_osdep1_write);
 937static PDCS_ATTR(diagnostic, 0400, pdcs_diagnostic_read, NULL);
 938static PDCS_ATTR(fastsize, 0400, pdcs_fastsize_read, NULL);
 939static PDCS_ATTR(osdep2, 0600, pdcs_osdep2_read, pdcs_osdep2_write);
 940
 941static struct attribute *pdcs_subsys_attrs[] = {
 942        &pdcs_attr_size.attr,
 943        &pdcs_attr_autoboot.attr,
 944        &pdcs_attr_autosearch.attr,
 945        &pdcs_attr_timer.attr,
 946        &pdcs_attr_osid.attr,
 947        &pdcs_attr_osdep1.attr,
 948        &pdcs_attr_diagnostic.attr,
 949        &pdcs_attr_fastsize.attr,
 950        &pdcs_attr_osdep2.attr,
 951        NULL,
 952};
 953
 954static struct attribute_group pdcs_attr_group = {
 955        .attrs = pdcs_subsys_attrs,
 956};
 957
 958static struct kobject *stable_kobj;
 959static struct kset *paths_kset;
 960
 961/**
 962 * pdcs_register_pathentries - Prepares path entries kobjects for sysfs usage.
 963 * 
 964 * It creates kobjects corresponding to each path entry with nice sysfs
 965 * links to the real device. This is where the magic takes place: when
 966 * registering the subsystem attributes during module init, each kobject hereby
 967 * created will show in the sysfs tree as a folder containing files as defined
 968 * by path_subsys_attr[].
 969 */
 970static inline int __init
 971pdcs_register_pathentries(void)
 972{
 973        unsigned short i;
 974        struct pdcspath_entry *entry;
 975        int err;
 976        
 977        /* Initialize the entries rw_lock before anything else */
 978        for (i = 0; (entry = pdcspath_entries[i]); i++)
 979                rwlock_init(&entry->rw_lock);
 980
 981        for (i = 0; (entry = pdcspath_entries[i]); i++) {
 982                write_lock(&entry->rw_lock);
 983                err = pdcspath_fetch(entry);
 984                write_unlock(&entry->rw_lock);
 985
 986                if (err < 0)
 987                        continue;
 988
 989                entry->kobj.kset = paths_kset;
 990                err = kobject_init_and_add(&entry->kobj, &ktype_pdcspath, NULL,
 991                                           "%s", entry->name);
 992                if (err)
 993                        return err;
 994
 995                /* kobject is now registered */
 996                write_lock(&entry->rw_lock);
 997                entry->ready = 2;
 998                
 999                /* Add a nice symlink to the real device */
1000                if (entry->dev) {
1001                        err = sysfs_create_link(&entry->kobj, &entry->dev->kobj, "device");
1002                        WARN_ON(err);
1003                }
1004
1005                write_unlock(&entry->rw_lock);
1006                kobject_uevent(&entry->kobj, KOBJ_ADD);
1007        }
1008        
1009        return 0;
1010}
1011
1012/**
1013 * pdcs_unregister_pathentries - Routine called when unregistering the module.
1014 */
1015static inline void
1016pdcs_unregister_pathentries(void)
1017{
1018        unsigned short i;
1019        struct pdcspath_entry *entry;
1020        
1021        for (i = 0; (entry = pdcspath_entries[i]); i++) {
1022                read_lock(&entry->rw_lock);
1023                if (entry->ready >= 2)
1024                        kobject_put(&entry->kobj);
1025                read_unlock(&entry->rw_lock);
1026        }
1027}
1028
1029/*
1030 * For now we register the stable subsystem with the firmware subsystem
1031 * and the paths subsystem with the stable subsystem
1032 */
1033static int __init
1034pdc_stable_init(void)
1035{
1036        int rc = 0, error = 0;
1037        u32 result;
1038
1039        /* find the size of the stable storage */
1040        if (pdc_stable_get_size(&pdcs_size) != PDC_OK) 
1041                return -ENODEV;
1042
1043        /* make sure we have enough data */
1044        if (pdcs_size < 96)
1045                return -ENODATA;
1046
1047        printk(KERN_INFO PDCS_PREFIX " facility v%s\n", PDCS_VERSION);
1048
1049        /* get OSID */
1050        if (pdc_stable_read(PDCS_ADDR_OSID, &result, sizeof(result)) != PDC_OK)
1051                return -EIO;
1052
1053        /* the actual result is 16 bits away */
1054        pdcs_osid = (u16)(result >> 16);
1055
1056        /* For now we'll register the directory at /sys/firmware/stable */
1057        stable_kobj = kobject_create_and_add("stable", firmware_kobj);
1058        if (!stable_kobj) {
1059                rc = -ENOMEM;
1060                goto fail_firmreg;
1061        }
1062
1063        /* Don't forget the root entries */
1064        error = sysfs_create_group(stable_kobj, &pdcs_attr_group);
1065
1066        /* register the paths kset as a child of the stable kset */
1067        paths_kset = kset_create_and_add("paths", NULL, stable_kobj);
1068        if (!paths_kset) {
1069                rc = -ENOMEM;
1070                goto fail_ksetreg;
1071        }
1072
1073        /* now we create all "files" for the paths kset */
1074        if ((rc = pdcs_register_pathentries()))
1075                goto fail_pdcsreg;
1076
1077        return rc;
1078        
1079fail_pdcsreg:
1080        pdcs_unregister_pathentries();
1081        kset_unregister(paths_kset);
1082        
1083fail_ksetreg:
1084        kobject_put(stable_kobj);
1085        
1086fail_firmreg:
1087        printk(KERN_INFO PDCS_PREFIX " bailing out\n");
1088        return rc;
1089}
1090
1091static void __exit
1092pdc_stable_exit(void)
1093{
1094        pdcs_unregister_pathentries();
1095        kset_unregister(paths_kset);
1096        kobject_put(stable_kobj);
1097}
1098
1099
1100module_init(pdc_stable_init);
1101module_exit(pdc_stable_exit);
1102
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