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