drivers/spi/spi-butterfly.c

   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
  61 static inline struct butterfly *spidev_to_pp(struct spi_device *spi)
  62 {
  63         return spi->controller_data;
  64 }
  65
  66
  67 struct 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
  84 static inline void
  85 setsck(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
 100 static inline void
 101 setmosi(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
 116 static 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
 129 static 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
 155 static u32
 156 butterfly_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 */
 166 static 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
 187 static 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 */
 195 static struct butterfly *butterfly;
 196
 197 static 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 = 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         pr_info("%s: AVR Butterfly\n", p->name);
 293         butterfly = pp;
 294         return;
 295
 296 clean2:
 297         /* turn off VCC */
 298         parport_write_data(pp->port, 0);
 299
 300         parport_release(pp->pd);
 301 clean1:
 302         parport_unregister_device(pd);
 303 clean0:
 304         (void) spi_master_put(pp->bitbang.master);
 305 done:
 306         pr_debug("%s: butterfly probe, fail %d\n", p->name, status);
 307 }
 308
 309 static void butterfly_detach(struct parport *p)
 310 {
 311         struct butterfly        *pp;
 312         int                     status;
 313
 314         /* FIXME this global is ugly ... but, how to quickly get from
 315          * the parport to the "struct butterfly" associated with it?
 316          * "old school" driver-internal device lists?
 317          */
 318         if (!butterfly || butterfly->port != p)
 319                 return;
 320         pp = butterfly;
 321         butterfly = NULL;
 322
 323         /* stop() unregisters child devices too */
 324         status = spi_bitbang_stop(&pp->bitbang);
 325
 326         /* turn off VCC */
 327         parport_write_data(pp->port, 0);
 328         msleep(10);
 329
 330         parport_release(pp->pd);
 331         parport_unregister_device(pp->pd);
 332
 333         (void) spi_master_put(pp->bitbang.master);
 334 }
 335
 336 static struct parport_driver butterfly_driver = {
 337         .name =         "spi_butterfly",
 338         .attach =       butterfly_attach,
 339         .detach =       butterfly_detach,
 340 };
 341
 342
 343 static int __init butterfly_init(void)
 344 {
 345         return parport_register_driver(&butterfly_driver);
 346 }
 347 device_initcall(butterfly_init);
 348
 349 static void __exit butterfly_exit(void)
 350 {
 351         parport_unregister_driver(&butterfly_driver);
 352 }
 353 module_exit(butterfly_exit);
 354
 355 MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");
 356 MODULE_LICENSE("GPL");