drivers/spi/spi_butterfly.c

   1 /*
   2  * spi_butterfly.c - 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/config.h>
  21 #include <linux/kernel.h>
  22 #include <linux/init.h>
  23 #include <linux/delay.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/parport.h>
  26
  27 #include <linux/spi/spi.h>
  28 #include <linux/spi/spi_bitbang.h>
  29 #include <linux/spi/flash.h>
  30
  31 #include <linux/mtd/partitions.h>
  32
  33
  34 /*
  35  * This uses SPI to talk with an "AVR Butterfly", which is a $US20 card
  36  * with a battery powered AVR microcontroller and lots of goodies.  You
  37  * can use GCC to develop firmware for this.
  38  *
  39  * See Documentation/spi/butterfly for information about how to build
  40  * and use this custom parallel port cable.
  41  */
  42
  43 #undef  HAVE_USI        /* nyet */
  44
  45
  46 /* DATA output bits (pins 2..9 == D0..D7) */
  47 #define butterfly_nreset (1 << 1)               /* pin 3 */
  48
  49 #define spi_sck_bit     (1 << 0)                /* pin 2 */
  50 #define spi_mosi_bit    (1 << 7)                /* pin 9 */
  51
  52 #define usi_sck_bit     (1 << 3)                /* pin 5 */
  53 #define usi_mosi_bit    (1 << 4)                /* pin 6 */
  54
  55 #define vcc_bits        ((1 << 6) | (1 << 5))   /* pins 7, 8 */
  56
  57 /* STATUS input bits */
  58 #define spi_miso_bit    PARPORT_STATUS_BUSY     /* pin 11 */
  59
  60 #define usi_miso_bit    PARPORT_STATUS_PAPEROUT /* pin 12 */
  61
  62 /* CONTROL output bits */
  63 #define spi_cs_bit      PARPORT_CONTROL_SELECT  /* pin 17 */
  64 /* USI uses no chipselect */
  65
  66
  67
  68 static inline struct butterfly *spidev_to_pp(struct spi_device *spi)
  69 {
  70         return spi->controller_data;
  71 }
  72
  73 static inline int is_usidev(struct spi_device *spi)
  74 {
  75 #ifdef  HAVE_USI
  76         return spi->chip_select != 1;
  77 #else
  78         return 0;
  79 #endif
  80 }
  81
  82
  83 struct butterfly {
  84         /* REVISIT ... for now, this must be first */
  85         struct spi_bitbang      bitbang;
  86
  87         struct parport          *port;
  88         struct pardevice        *pd;
  89
  90         u8                      lastbyte;
  91
  92         struct spi_device       *dataflash;
  93         struct spi_device       *butterfly;
  94         struct spi_board_info   info[2];
  95
  96 };
  97
  98 /*----------------------------------------------------------------------*/
  99
 100 /*
 101  * these routines may be slower than necessary because they're hiding
 102  * the fact that there are two different SPI busses on this cable: one
 103  * to the DataFlash chip (or AVR SPI controller), the other to the
 104  * AVR USI controller.
 105  */
 106
 107 static inline void
 108 setsck(struct spi_device *spi, int is_on)
 109 {
 110         struct butterfly        *pp = spidev_to_pp(spi);
 111         u8                      bit, byte = pp->lastbyte;
 112
 113         if (is_usidev(spi))
 114                 bit = usi_sck_bit;
 115         else
 116                 bit = spi_sck_bit;
 117
 118         if (is_on)
 119                 byte |= bit;
 120         else
 121                 byte &= ~bit;
 122         parport_write_data(pp->port, byte);
 123         pp->lastbyte = byte;
 124 }
 125
 126 static inline void
 127 setmosi(struct spi_device *spi, int is_on)
 128 {
 129         struct butterfly        *pp = spidev_to_pp(spi);
 130         u8                      bit, byte = pp->lastbyte;
 131
 132         if (is_usidev(spi))
 133                 bit = usi_mosi_bit;
 134         else
 135                 bit = spi_mosi_bit;
 136
 137         if (is_on)
 138                 byte |= bit;
 139         else
 140                 byte &= ~bit;
 141         parport_write_data(pp->port, byte);
 142         pp->lastbyte = byte;
 143 }
 144
 145 static inline int getmiso(struct spi_device *spi)
 146 {
 147         struct butterfly        *pp = spidev_to_pp(spi);
 148         int                     value;
 149         u8                      bit;
 150
 151         if (is_usidev(spi))
 152                 bit = usi_miso_bit;
 153         else
 154                 bit = spi_miso_bit;
 155
 156         /* only STATUS_BUSY is NOT negated */
 157         value = !(parport_read_status(pp->port) & bit);
 158         return (bit == PARPORT_STATUS_BUSY) ? value : !value;
 159 }
 160
 161 static void butterfly_chipselect(struct spi_device *spi, int value)
 162 {
 163         struct butterfly        *pp = spidev_to_pp(spi);
 164
 165         /* set default clock polarity */
 166         if (value != BITBANG_CS_INACTIVE)
 167                 setsck(spi, spi->mode & SPI_CPOL);
 168
 169         /* no chipselect on this USI link config */
 170         if (is_usidev(spi))
 171                 return;
 172
 173         /* here, value == "activate or not";
 174          * most PARPORT_CONTROL_* bits are negated, so we must
 175          * morph it to value == "bit value to write in control register"
 176          */
 177         if (spi_cs_bit == PARPORT_CONTROL_INIT)
 178                 value = !value;
 179
 180         parport_frob_control(pp->port, spi_cs_bit, value ? spi_cs_bit : 0);
 181 }
 182
 183
 184 /* we only needed to implement one mode here, and choose SPI_MODE_0 */
 185
 186 #define spidelay(X)     do{}while(0)
 187 //#define       spidelay        ndelay
 188
 189 #define EXPAND_BITBANG_TXRX
 190 #include <linux/spi/spi_bitbang.h>
 191
 192 static u32
 193 butterfly_txrx_word_mode0(struct spi_device *spi,
 194                 unsigned nsecs,
 195                 u32 word, u8 bits)
 196 {
 197         return bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits);
 198 }
 199
 200 /*----------------------------------------------------------------------*/
 201
 202 /* override default partitioning with cmdlinepart */
 203 static struct mtd_partition partitions[] = { {
 204         /* JFFS2 wants partitions of 4*N blocks for this device,
 205          * so sectors 0 and 1 can't be partitions by themselves.
 206          */
 207
 208         /* sector 0 = 8 pages * 264 bytes/page (1 block)
 209          * sector 1 = 248 pages * 264 bytes/page
 210          */
 211         .name           = "bookkeeping",        // 66 KB
 212         .offset         = 0,
 213         .size           = (8 + 248) * 264,
 214 //      .mask_flags     = MTD_WRITEABLE,
 215 }, {
 216         /* sector 2 = 256 pages * 264 bytes/page
 217          * sectors 3-5 = 512 pages * 264 bytes/page
 218          */
 219         .name           = "filesystem",         // 462 KB
 220         .offset         = MTDPART_OFS_APPEND,
 221         .size           = MTDPART_SIZ_FULL,
 222 } };
 223
 224 static struct flash_platform_data flash = {
 225         .name           = "butterflash",
 226         .parts          = partitions,
 227         .nr_parts       = ARRAY_SIZE(partitions),
 228 };
 229
 230
 231 /* REVISIT remove this ugly global and its "only one" limitation */
 232 static struct butterfly *butterfly;
 233
 234 static void butterfly_attach(struct parport *p)
 235 {
 236         struct pardevice        *pd;
 237         int                     status;
 238         struct butterfly        *pp;
 239         struct spi_master       *master;
 240         struct platform_device  *pdev;
 241
 242         if (butterfly)
 243                 return;
 244
 245         /* REVISIT:  this just _assumes_ a butterfly is there ... no probe,
 246          * and no way to be selective about what it binds to.
 247          */
 248
 249         /* FIXME where should master->cdev.dev come from?
 250          * e.g. /sys/bus/pnp0/00:0b, some PCI thing, etc
 251          * setting up a platform device like this is an ugly kluge...
 252          */
 253         pdev = platform_device_register_simple("butterfly", -1, NULL, 0);
 254
 255         master = spi_alloc_master(&pdev->dev, sizeof *pp);
 256         if (!master) {
 257                 status = -ENOMEM;
 258                 goto done;
 259         }
 260         pp = spi_master_get_devdata(master);
 261
 262         /*
 263          * SPI and bitbang hookup
 264          *
 265          * use default setup(), cleanup(), and transfer() methods; and
 266          * only bother implementing mode 0.  Start it later.
 267          */
 268         master->bus_num = 42;
 269         master->num_chipselect = 2;
 270
 271         pp->bitbang.master = spi_master_get(master);
 272         pp->bitbang.chipselect = butterfly_chipselect;
 273         pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0;
 274
 275         /*
 276          * parport hookup
 277          */
 278         pp->port = p;
 279         pd = parport_register_device(p, "spi_butterfly",
 280                         NULL, NULL, NULL,
 281                         0 /* FLAGS */, pp);
 282         if (!pd) {
 283                 status = -ENOMEM;
 284                 goto clean0;
 285         }
 286         pp->pd = pd;
 287
 288         status = parport_claim(pd);
 289         if (status < 0)
 290                 goto clean1;
 291
 292         /*
 293          * Butterfly reset, powerup, run firmware
 294          */
 295         pr_debug("%s: powerup/reset Butterfly\n", p->name);
 296
 297         /* nCS for dataflash (this bit is inverted on output) */
 298         parport_frob_control(pp->port, spi_cs_bit, 0);
 299
 300         /* stabilize power with chip in reset (nRESET), and
 301          * both spi_sck_bit and usi_sck_bit clear (CPOL=0)
 302          */
 303         pp->lastbyte |= vcc_bits;
 304         parport_write_data(pp->port, pp->lastbyte);
 305         msleep(5);
 306
 307         /* take it out of reset; assume long reset delay */
 308         pp->lastbyte |= butterfly_nreset;
 309         parport_write_data(pp->port, pp->lastbyte);
 310         msleep(100);
 311
 312
 313         /*
 314          * Start SPI ... for now, hide that we're two physical busses.
 315          */
 316         status = spi_bitbang_start(&pp->bitbang);
 317         if (status < 0)
 318                 goto clean2;
 319
 320         /* Bus 1 lets us talk to at45db041b (firmware disables AVR SPI), AVR
 321          * (firmware resets at45, acts as spi slave) or neither (we ignore
 322          * both, AVR uses AT45).  Here we expect firmware for the first option.
 323          */
 324
 325         pp->info[0].max_speed_hz = 15 * 1000 * 1000;
 326         strcpy(pp->info[0].modalias, "mtd_dataflash");
 327         pp->info[0].platform_data = &flash;
 328         pp->info[0].chip_select = 1;
 329         pp->info[0].controller_data = pp;
 330         pp->dataflash = spi_new_device(pp->bitbang.master, &pp->info[0]);
 331         if (pp->dataflash)
 332                 pr_debug("%s: dataflash at %s\n", p->name,
 333                                 pp->dataflash->dev.bus_id);
 334
 335 #ifdef  HAVE_USI
 336         /* Bus 2 is only for talking to the AVR, and it can work no
 337          * matter who masters bus 1; needs appropriate AVR firmware.
 338          */
 339         pp->info[1].max_speed_hz = 10 /* ?? */ * 1000 * 1000;
 340         strcpy(pp->info[1].modalias, "butterfly");
 341         // pp->info[1].platform_data = ... TBD ... ;
 342         pp->info[1].chip_select = 2,
 343         pp->info[1].controller_data = pp;
 344         pp->butterfly = spi_new_device(pp->bitbang.master, &pp->info[1]);
 345         if (pp->butterfly)
 346                 pr_debug("%s: butterfly at %s\n", p->name,
 347                                 pp->butterfly->dev.bus_id);
 348
 349         /* FIXME setup ACK for the IRQ line ...  */
 350 #endif
 351
 352         // dev_info(_what?_, ...)
 353         pr_info("%s: AVR Butterfly\n", p->name);
 354         butterfly = pp;
 355         return;
 356
 357 clean2:
 358         /* turn off VCC */
 359         parport_write_data(pp->port, 0);
 360
 361         parport_release(pp->pd);
 362 clean1:
 363         parport_unregister_device(pd);
 364 clean0:
 365         (void) spi_master_put(pp->bitbang.master);
 366 done:
 367         platform_device_unregister(pdev);
 368         pr_debug("%s: butterfly probe, fail %d\n", p->name, status);
 369 }
 370
 371 static void butterfly_detach(struct parport *p)
 372 {
 373         struct butterfly        *pp;
 374         struct platform_device  *pdev;
 375         int                     status;
 376
 377         /* FIXME this global is ugly ... but, how to quickly get from
 378          * the parport to the "struct butterfly" associated with it?
 379          * "old school" driver-internal device lists?
 380          */
 381         if (!butterfly || butterfly->port != p)
 382                 return;
 383         pp = butterfly;
 384         butterfly = NULL;
 385
 386         /* stop() unregisters child devices too */
 387         pdev = to_platform_device(pp->bitbang.master->cdev.dev);
 388         status = spi_bitbang_stop(&pp->bitbang);
 389
 390         /* turn off VCC */
 391         parport_write_data(pp->port, 0);
 392         msleep(10);
 393
 394         parport_release(pp->pd);
 395         parport_unregister_device(pp->pd);
 396
 397         (void) spi_master_put(pp->bitbang.master);
 398
 399         platform_device_unregister(pdev);
 400 }
 401
 402 static struct parport_driver butterfly_driver = {
 403         .name =         "spi_butterfly",
 404         .attach =       butterfly_attach,
 405         .detach =       butterfly_detach,
 406 };
 407
 408
 409 static int __init butterfly_init(void)
 410 {
 411         return parport_register_driver(&butterfly_driver);
 412 }
 413 device_initcall(butterfly_init);
 414
 415 static void __exit butterfly_exit(void)
 416 {
 417         parport_unregister_driver(&butterfly_driver);
 418 }
 419 module_exit(butterfly_exit);
 420
 421 MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");
 422 MODULE_LICENSE("GPL");