linux/drivers/spi/spi-butterfly.c
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   1/*
   2 * parport-to-butterfly adapter
   3 *
   4 * Copyright (C) 2005 David Brownell
   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 as published by
   8 * the Free Software Foundation; either version 2 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program; if not, write to the Free Software
  18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20#include <linux/kernel.h>
  21#include <linux/init.h>
  22#include <linux/delay.h>
  23#include <linux/module.h>
  24#include <linux/device.h>
  25#include <linux/parport.h>
  26
  27#include <linux/sched.h>
  28#include <linux/spi/spi.h>
  29#include <linux/spi/spi_bitbang.h>
  30#include <linux/spi/flash.h>
  31
  32#include <linux/mtd/partitions.h>
  33
  34
  35/*
  36 * This uses SPI to talk with an "AVR Butterfly", which is a $US20 card
  37 * with a battery powered AVR microcontroller and lots of goodies.  You
  38 * can use GCC to develop firmware for this.
  39 *
  40 * See Documentation/spi/butterfly for information about how to build
  41 * and use this custom parallel port cable.
  42 */
  43
  44
  45/* DATA output bits (pins 2..9 == D0..D7) */
  46#define butterfly_nreset (1 << 1)               /* pin 3 */
  47
  48#define spi_sck_bit     (1 << 0)                /* pin 2 */
  49#define spi_mosi_bit    (1 << 7)                /* pin 9 */
  50
  51#define vcc_bits        ((1 << 6) | (1 << 5))   /* pins 7, 8 */
  52
  53/* STATUS input bits */
  54#define spi_miso_bit    PARPORT_STATUS_BUSY     /* pin 11 */
  55
  56/* CONTROL output bits */
  57#define spi_cs_bit      PARPORT_CONTROL_SELECT  /* pin 17 */
  58
  59
  60
  61static inline struct butterfly *spidev_to_pp(struct spi_device *spi)
  62{
  63        return spi->controller_data;
  64}
  65
  66
  67struct butterfly {
  68        /* REVISIT ... for now, this must be first */
  69        struct spi_bitbang      bitbang;
  70
  71        struct parport          *port;
  72        struct pardevice        *pd;
  73
  74        u8                      lastbyte;
  75
  76        struct spi_device       *dataflash;
  77        struct spi_device       *butterfly;
  78        struct spi_board_info   info[2];
  79
  80};
  81
  82/*----------------------------------------------------------------------*/
  83
  84static inline void
  85setsck(struct spi_device *spi, int is_on)
  86{
  87        struct butterfly        *pp = spidev_to_pp(spi);
  88        u8                      bit, byte = pp->lastbyte;
  89
  90        bit = spi_sck_bit;
  91
  92        if (is_on)
  93                byte |= bit;
  94        else
  95                byte &= ~bit;
  96        parport_write_data(pp->port, byte);
  97        pp->lastbyte = byte;
  98}
  99
 100static inline void
 101setmosi(struct spi_device *spi, int is_on)
 102{
 103        struct butterfly        *pp = spidev_to_pp(spi);
 104        u8                      bit, byte = pp->lastbyte;
 105
 106        bit = spi_mosi_bit;
 107
 108        if (is_on)
 109                byte |= bit;
 110        else
 111                byte &= ~bit;
 112        parport_write_data(pp->port, byte);
 113        pp->lastbyte = byte;
 114}
 115
 116static inline int getmiso(struct spi_device *spi)
 117{
 118        struct butterfly        *pp = spidev_to_pp(spi);
 119        int                     value;
 120        u8                      bit;
 121
 122        bit = spi_miso_bit;
 123
 124        /* only STATUS_BUSY is NOT negated */
 125        value = !(parport_read_status(pp->port) & bit);
 126        return (bit == PARPORT_STATUS_BUSY) ? value : !value;
 127}
 128
 129static void butterfly_chipselect(struct spi_device *spi, int value)
 130{
 131        struct butterfly        *pp = spidev_to_pp(spi);
 132
 133        /* set default clock polarity */
 134        if (value != BITBANG_CS_INACTIVE)
 135                setsck(spi, spi->mode & SPI_CPOL);
 136
 137        /* here, value == "activate or not";
 138         * most PARPORT_CONTROL_* bits are negated, so we must
 139         * morph it to value == "bit value to write in control register"
 140         */
 141        if (spi_cs_bit == PARPORT_CONTROL_INIT)
 142                value = !value;
 143
 144        parport_frob_control(pp->port, spi_cs_bit, value ? spi_cs_bit : 0);
 145}
 146
 147
 148/* we only needed to implement one mode here, and choose SPI_MODE_0 */
 149
 150#define spidelay(X)     do{}while(0)
 151//#define       spidelay        ndelay
 152
 153#include "spi-bitbang-txrx.h"
 154
 155static u32
 156butterfly_txrx_word_mode0(struct spi_device *spi,
 157                unsigned nsecs,
 158                u32 word, u8 bits)
 159{
 160        return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
 161}
 162
 163/*----------------------------------------------------------------------*/
 164
 165/* override default partitioning with cmdlinepart */
 166static struct mtd_partition partitions[] = { {
 167        /* JFFS2 wants partitions of 4*N blocks for this device,
 168         * so sectors 0 and 1 can't be partitions by themselves.
 169         */
 170
 171        /* sector 0 = 8 pages * 264 bytes/page (1 block)
 172         * sector 1 = 248 pages * 264 bytes/page
 173         */
 174        .name           = "bookkeeping",        // 66 KB
 175        .offset         = 0,
 176        .size           = (8 + 248) * 264,
 177//      .mask_flags     = MTD_WRITEABLE,
 178}, {
 179        /* sector 2 = 256 pages * 264 bytes/page
 180         * sectors 3-5 = 512 pages * 264 bytes/page
 181         */
 182        .name           = "filesystem",         // 462 KB
 183        .offset         = MTDPART_OFS_APPEND,
 184        .size           = MTDPART_SIZ_FULL,
 185} };
 186
 187static struct flash_platform_data flash = {
 188        .name           = "butterflash",
 189        .parts          = partitions,
 190        .nr_parts       = ARRAY_SIZE(partitions),
 191};
 192
 193
 194/* REVISIT remove this ugly global and its "only one" limitation */
 195static struct butterfly *butterfly;
 196
 197static void butterfly_attach(struct parport *p)
 198{
 199        struct pardevice        *pd;
 200        int                     status;
 201        struct butterfly        *pp;
 202        struct spi_master       *master;
 203        struct device           *dev = p->physport->dev;
 204
 205        if (butterfly || !dev)
 206                return;
 207
 208        /* REVISIT:  this just _assumes_ a butterfly is there ... no probe,
 209         * and no way to be selective about what it binds to.
 210         */
 211
 212        master = spi_alloc_master(dev, sizeof *pp);
 213        if (!master) {
 214                status = -ENOMEM;
 215                goto done;
 216        }
 217        pp = spi_master_get_devdata(master);
 218
 219        /*
 220         * SPI and bitbang hookup
 221         *
 222         * use default setup(), cleanup(), and transfer() methods; and
 223         * only bother implementing mode 0.  Start it later.
 224         */
 225        master->bus_num = 42;
 226        master->num_chipselect = 2;
 227
 228        pp->bitbang.master = spi_master_get(master);
 229        pp->bitbang.chipselect = butterfly_chipselect;
 230        pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0;
 231
 232        /*
 233         * parport hookup
 234         */
 235        pp->port = p;
 236        pd = parport_register_device(p, "spi_butterfly",
 237                        NULL, NULL, NULL,
 238                        0 /* FLAGS */, pp);
 239        if (!pd) {
 240                status = -ENOMEM;
 241                goto clean0;
 242        }
 243        pp->pd = pd;
 244
 245        status = parport_claim(pd);
 246        if (status < 0)
 247                goto clean1;
 248
 249        /*
 250         * Butterfly reset, powerup, run firmware
 251         */
 252        pr_debug("%s: powerup/reset Butterfly\n", p->name);
 253
 254        /* nCS for dataflash (this bit is inverted on output) */
 255        parport_frob_control(pp->port, spi_cs_bit, 0);
 256
 257        /* stabilize power with chip in reset (nRESET), and
 258         * spi_sck_bit clear (CPOL=0)
 259         */
 260        pp->lastbyte |= vcc_bits;
 261        parport_write_data(pp->port, pp->lastbyte);
 262        msleep(5);
 263
 264        /* take it out of reset; assume long reset delay */
 265        pp->lastbyte |= butterfly_nreset;
 266        parport_write_data(pp->port, pp->lastbyte);
 267        msleep(100);
 268
 269
 270        /*
 271         * Start SPI ... for now, hide that we're two physical busses.
 272         */
 273        status = spi_bitbang_start(&pp->bitbang);
 274        if (status < 0)
 275                goto clean2;
 276
 277        /* Bus 1 lets us talk to at45db041b (firmware disables AVR SPI), AVR
 278         * (firmware resets at45, acts as spi slave) or neither (we ignore
 279         * both, AVR uses AT45).  Here we expect firmware for the first option.
 280         */
 281
 282        pp->info[0].max_speed_hz = 15 * 1000 * 1000;
 283        strcpy(pp->info[0].modalias, "mtd_dataflash");
 284        pp->info[0].platform_data = &flash;
 285        pp->info[0].chip_select = 1;
 286        pp->info[0].controller_data = pp;
 287        pp->dataflash = spi_new_device(pp->bitbang.master, &pp->info[0]);
 288        if (pp->dataflash)
 289                pr_debug("%s: dataflash at %s\n", p->name,
 290                                dev_name(&pp->dataflash->dev));
 291
 292        // dev_info(_what?_, ...)
 293        pr_info("%s: AVR Butterfly\n", p->name);
 294        butterfly = pp;
 295        return;
 296
 297clean2:
 298        /* turn off VCC */
 299        parport_write_data(pp->port, 0);
 300
 301        parport_release(pp->pd);
 302clean1:
 303        parport_unregister_device(pd);
 304clean0:
 305        (void) spi_master_put(pp->bitbang.master);
 306done:
 307        pr_debug("%s: butterfly probe, fail %d\n", p->name, status);
 308}
 309
 310static void butterfly_detach(struct parport *p)
 311{
 312        struct butterfly        *pp;
 313        int                     status;
 314
 315        /* FIXME this global is ugly ... but, how to quickly get from
 316         * the parport to the "struct butterfly" associated with it?
 317         * "old school" driver-internal device lists?
 318         */
 319        if (!butterfly || butterfly->port != p)
 320                return;
 321        pp = butterfly;
 322        butterfly = NULL;
 323
 324        /* stop() unregisters child devices too */
 325        status = spi_bitbang_stop(&pp->bitbang);
 326
 327        /* turn off VCC */
 328        parport_write_data(pp->port, 0);
 329        msleep(10);
 330
 331        parport_release(pp->pd);
 332        parport_unregister_device(pp->pd);
 333
 334        (void) spi_master_put(pp->bitbang.master);
 335}
 336
 337static struct parport_driver butterfly_driver = {
 338        .name =         "spi_butterfly",
 339        .attach =       butterfly_attach,
 340        .detach =       butterfly_detach,
 341};
 342
 343
 344static int __init butterfly_init(void)
 345{
 346        return parport_register_driver(&butterfly_driver);
 347}
 348device_initcall(butterfly_init);
 349
 350static void __exit butterfly_exit(void)
 351{
 352        parport_unregister_driver(&butterfly_driver);
 353}
 354module_exit(butterfly_exit);
 355
 356MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");
 357MODULE_LICENSE("GPL");
 358
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