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