drivers/gpio/mcp23s08.c

   1 /*
   2  * mcp23s08.c - SPI gpio expander driver
   3  */
   4
   5 #include <linux/kernel.h>
   6 #include <linux/device.h>
   7 #include <linux/workqueue.h>
   8 #include <linux/mutex.h>
   9 #include <linux/gpio.h>
  10 #include <linux/spi/spi.h>
  11 #include <linux/spi/mcp23s08.h>
  12
  13
  14 /* Registers are all 8 bits wide.
  15  *
  16  * The mcp23s17 has twice as many bits, and can be configured to work
  17  * with either 16 bit registers or with two adjacent 8 bit banks.
  18  *
  19  * Also, there are I2C versions of both chips.
  20  */
  21 #define MCP_IODIR       0x00            /* init/reset:  all ones */
  22 #define MCP_IPOL        0x01
  23 #define MCP_GPINTEN     0x02
  24 #define MCP_DEFVAL      0x03
  25 #define MCP_INTCON      0x04
  26 #define MCP_IOCON       0x05
  27 #       define IOCON_SEQOP      (1 << 5)
  28 #       define IOCON_HAEN       (1 << 3)
  29 #       define IOCON_ODR        (1 << 2)
  30 #       define IOCON_INTPOL     (1 << 1)
  31 #define MCP_GPPU        0x06
  32 #define MCP_INTF        0x07
  33 #define MCP_INTCAP      0x08
  34 #define MCP_GPIO        0x09
  35 #define MCP_OLAT        0x0a
  36
  37 struct mcp23s08 {
  38         struct spi_device       *spi;
  39         u8                      addr;
  40
  41         u8                      cache[11];
  42         /* lock protects the cached values */
  43         struct mutex            lock;
  44
  45         struct gpio_chip        chip;
  46
  47         struct work_struct      work;
  48 };
  49
  50 /* A given spi_device can represent up to four mcp23s08 chips
  51  * sharing the same chipselect but using different addresses
  52  * (e.g. chips #0 and #3 might be populated, but not #1 or $2).
  53  * Driver data holds all the per-chip data.
  54  */
  55 struct mcp23s08_driver_data {
  56         unsigned                ngpio;
  57         struct mcp23s08         *mcp[4];
  58         struct mcp23s08         chip[];
  59 };
  60
  61 static int mcp23s08_read(struct mcp23s08 *mcp, unsigned reg)
  62 {
  63         u8      tx[2], rx[1];
  64         int     status;
  65
  66         tx[0] = mcp->addr | 0x01;
  67         tx[1] = reg;
  68         status = spi_write_then_read(mcp->spi, tx, sizeof tx, rx, sizeof rx);
  69         return (status < 0) ? status : rx[0];
  70 }
  71
  72 static int mcp23s08_write(struct mcp23s08 *mcp, unsigned reg, u8 val)
  73 {
  74         u8      tx[3];
  75
  76         tx[0] = mcp->addr;
  77         tx[1] = reg;
  78         tx[2] = val;
  79         return spi_write_then_read(mcp->spi, tx, sizeof tx, NULL, 0);
  80 }
  81
  82 static int
  83 mcp23s08_read_regs(struct mcp23s08 *mcp, unsigned reg, u8 *vals, unsigned n)
  84 {
  85         u8      tx[2];
  86
  87         if ((n + reg) > sizeof mcp->cache)
  88                 return -EINVAL;
  89         tx[0] = mcp->addr | 0x01;
  90         tx[1] = reg;
  91         return spi_write_then_read(mcp->spi, tx, sizeof tx, vals, n);
  92 }
  93
  94 /*----------------------------------------------------------------------*/
  95
  96 static int mcp23s08_direction_input(struct gpio_chip *chip, unsigned offset)
  97 {
  98         struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
  99         int status;
 100
 101         mutex_lock(&mcp->lock);
 102         mcp->cache[MCP_IODIR] |= (1 << offset);
 103         status = mcp23s08_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
 104         mutex_unlock(&mcp->lock);
 105         return status;
 106 }
 107
 108 static int mcp23s08_get(struct gpio_chip *chip, unsigned offset)
 109 {
 110         struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
 111         int status;
 112
 113         mutex_lock(&mcp->lock);
 114
 115         /* REVISIT reading this clears any IRQ ... */
 116         status = mcp23s08_read(mcp, MCP_GPIO);
 117         if (status < 0)
 118                 status = 0;
 119         else {
 120                 mcp->cache[MCP_GPIO] = status;
 121                 status = !!(status & (1 << offset));
 122         }
 123         mutex_unlock(&mcp->lock);
 124         return status;
 125 }
 126
 127 static int __mcp23s08_set(struct mcp23s08 *mcp, unsigned mask, int value)
 128 {
 129         u8 olat = mcp->cache[MCP_OLAT];
 130
 131         if (value)
 132                 olat |= mask;
 133         else
 134                 olat &= ~mask;
 135         mcp->cache[MCP_OLAT] = olat;
 136         return mcp23s08_write(mcp, MCP_OLAT, olat);
 137 }
 138
 139 static void mcp23s08_set(struct gpio_chip *chip, unsigned offset, int value)
 140 {
 141         struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
 142         u8 mask = 1 << offset;
 143
 144         mutex_lock(&mcp->lock);
 145         __mcp23s08_set(mcp, mask, value);
 146         mutex_unlock(&mcp->lock);
 147 }
 148
 149 static int
 150 mcp23s08_direction_output(struct gpio_chip *chip, unsigned offset, int value)
 151 {
 152         struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
 153         u8 mask = 1 << offset;
 154         int status;
 155
 156         mutex_lock(&mcp->lock);
 157         status = __mcp23s08_set(mcp, mask, value);
 158         if (status == 0) {
 159                 mcp->cache[MCP_IODIR] &= ~mask;
 160                 status = mcp23s08_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
 161         }
 162         mutex_unlock(&mcp->lock);
 163         return status;
 164 }
 165
 166 /*----------------------------------------------------------------------*/
 167
 168 #ifdef CONFIG_DEBUG_FS
 169
 170 #include <linux/seq_file.h>
 171
 172 /*
 173  * This shows more info than the generic gpio dump code:
 174  * pullups, deglitching, open drain drive.
 175  */
 176 static void mcp23s08_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 177 {
 178         struct mcp23s08 *mcp;
 179         char            bank;
 180         int             t;
 181         unsigned        mask;
 182
 183         mcp = container_of(chip, struct mcp23s08, chip);
 184
 185         /* NOTE: we only handle one bank for now ... */
 186         bank = '0' + ((mcp->addr >> 1) & 0x3);
 187
 188         mutex_lock(&mcp->lock);
 189         t = mcp23s08_read_regs(mcp, 0, mcp->cache, sizeof mcp->cache);
 190         if (t < 0) {
 191                 seq_printf(s, " I/O ERROR %d\n", t);
 192                 goto done;
 193         }
 194
 195         for (t = 0, mask = 1; t < 8; t++, mask <<= 1) {
 196                 const char      *label;
 197
 198                 label = gpiochip_is_requested(chip, t);
 199                 if (!label)
 200                         continue;
 201
 202                 seq_printf(s, " gpio-%-3d P%c.%d (%-12s) %s %s %s",
 203                         chip->base + t, bank, t, label,
 204                         (mcp->cache[MCP_IODIR] & mask) ? "in " : "out",
 205                         (mcp->cache[MCP_GPIO] & mask) ? "hi" : "lo",
 206                         (mcp->cache[MCP_GPPU] & mask) ? "  " : "up");
 207                 /* NOTE:  ignoring the irq-related registers */
 208                 seq_printf(s, "\n");
 209         }
 210 done:
 211         mutex_unlock(&mcp->lock);
 212 }
 213
 214 #else
 215 #define mcp23s08_dbg_show       NULL
 216 #endif
 217
 218 /*----------------------------------------------------------------------*/
 219
 220 static int mcp23s08_probe_one(struct spi_device *spi, unsigned addr,
 221                 unsigned base, unsigned pullups)
 222 {
 223         struct mcp23s08_driver_data     *data = spi_get_drvdata(spi);
 224         struct mcp23s08                 *mcp = data->mcp[addr];
 225         int                             status;
 226         int                             do_update = 0;
 227
 228         mutex_init(&mcp->lock);
 229
 230         mcp->spi = spi;
 231         mcp->addr = 0x40 | (addr << 1);
 232
 233         mcp->chip.label = "mcp23s08",
 234
 235         mcp->chip.direction_input = mcp23s08_direction_input;
 236         mcp->chip.get = mcp23s08_get;
 237         mcp->chip.direction_output = mcp23s08_direction_output;
 238         mcp->chip.set = mcp23s08_set;
 239         mcp->chip.dbg_show = mcp23s08_dbg_show;
 240
 241         mcp->chip.base = base;
 242         mcp->chip.ngpio = 8;
 243         mcp->chip.can_sleep = 1;
 244         mcp->chip.dev = &spi->dev;
 245         mcp->chip.owner = THIS_MODULE;
 246
 247         /* verify MCP_IOCON.SEQOP = 0, so sequential reads work,
 248          * and MCP_IOCON.HAEN = 1, so we work with all chips.
 249          */
 250         status = mcp23s08_read(mcp, MCP_IOCON);
 251         if (status < 0)
 252                 goto fail;
 253         if ((status & IOCON_SEQOP) || !(status & IOCON_HAEN)) {
 254                 status &= ~IOCON_SEQOP;
 255                 status |= IOCON_HAEN;
 256                 status = mcp23s08_write(mcp, MCP_IOCON, (u8) status);
 257                 if (status < 0)
 258                         goto fail;
 259         }
 260
 261         /* configure ~100K pullups */
 262         status = mcp23s08_write(mcp, MCP_GPPU, pullups);
 263         if (status < 0)
 264                 goto fail;
 265
 266         status = mcp23s08_read_regs(mcp, 0, mcp->cache, sizeof mcp->cache);
 267         if (status < 0)
 268                 goto fail;
 269
 270         /* disable inverter on input */
 271         if (mcp->cache[MCP_IPOL] != 0) {
 272                 mcp->cache[MCP_IPOL] = 0;
 273                 do_update = 1;
 274         }
 275
 276         /* disable irqs */
 277         if (mcp->cache[MCP_GPINTEN] != 0) {
 278                 mcp->cache[MCP_GPINTEN] = 0;
 279                 do_update = 1;
 280         }
 281
 282         if (do_update) {
 283                 u8 tx[4];
 284
 285                 tx[0] = mcp->addr;
 286                 tx[1] = MCP_IPOL;
 287                 memcpy(&tx[2], &mcp->cache[MCP_IPOL], sizeof(tx) - 2);
 288                 status = spi_write_then_read(mcp->spi, tx, sizeof tx, NULL, 0);
 289                 if (status < 0)
 290                         goto fail;
 291         }
 292
 293         status = gpiochip_add(&mcp->chip);
 294 fail:
 295         if (status < 0)
 296                 dev_dbg(&spi->dev, "can't setup chip %d, --> %d\n",
 297                                 addr, status);
 298         return status;
 299 }
 300
 301 static int mcp23s08_probe(struct spi_device *spi)
 302 {
 303         struct mcp23s08_platform_data   *pdata;
 304         unsigned                        addr;
 305         unsigned                        chips = 0;
 306         struct mcp23s08_driver_data     *data;
 307         int                             status;
 308         unsigned                        base;
 309
 310         pdata = spi->dev.platform_data;
 311         if (!pdata || !gpio_is_valid(pdata->base)) {
 312                 dev_dbg(&spi->dev, "invalid or missing platform data\n");
 313                 return -EINVAL;
 314         }
 315
 316         for (addr = 0; addr < 4; addr++) {
 317                 if (!pdata->chip[addr].is_present)
 318                         continue;
 319                 chips++;
 320         }
 321         if (!chips)
 322                 return -ENODEV;
 323
 324         data = kzalloc(sizeof *data + chips * sizeof(struct mcp23s08),
 325                         GFP_KERNEL);
 326         if (!data)
 327                 return -ENOMEM;
 328         spi_set_drvdata(spi, data);
 329
 330         base = pdata->base;
 331         for (addr = 0; addr < 4; addr++) {
 332                 if (!pdata->chip[addr].is_present)
 333                         continue;
 334                 chips--;
 335                 data->mcp[addr] = &data->chip[chips];
 336                 status = mcp23s08_probe_one(spi, addr, base,
 337                                 pdata->chip[addr].pullups);
 338                 if (status < 0)
 339                         goto fail;
 340                 base += 8;
 341         }
 342         data->ngpio = base - pdata->base;
 343
 344         /* NOTE:  these chips have a relatively sane IRQ framework, with
 345          * per-signal masking and level/edge triggering.  It's not yet
 346          * handled here...
 347          */
 348
 349         if (pdata->setup) {
 350                 status = pdata->setup(spi,
 351                                 pdata->base, data->ngpio,
 352                                 pdata->context);
 353                 if (status < 0)
 354                         dev_dbg(&spi->dev, "setup --> %d\n", status);
 355         }
 356
 357         return 0;
 358
 359 fail:
 360         for (addr = 0; addr < 4; addr++) {
 361                 int tmp;
 362
 363                 if (!data->mcp[addr])
 364                         continue;
 365                 tmp = gpiochip_remove(&data->mcp[addr]->chip);
 366                 if (tmp < 0)
 367                         dev_err(&spi->dev, "%s --> %d\n", "remove", tmp);
 368         }
 369         kfree(data);
 370         return status;
 371 }
 372
 373 static int mcp23s08_remove(struct spi_device *spi)
 374 {
 375         struct mcp23s08_driver_data     *data = spi_get_drvdata(spi);
 376         struct mcp23s08_platform_data   *pdata = spi->dev.platform_data;
 377         unsigned                        addr;
 378         int                             status = 0;
 379
 380         if (pdata->teardown) {
 381                 status = pdata->teardown(spi,
 382                                 pdata->base, data->ngpio,
 383                                 pdata->context);
 384                 if (status < 0) {
 385                         dev_err(&spi->dev, "%s --> %d\n", "teardown", status);
 386                         return status;
 387                 }
 388         }
 389
 390         for (addr = 0; addr < 4; addr++) {
 391                 int tmp;
 392
 393                 if (!data->mcp[addr])
 394                         continue;
 395
 396                 tmp = gpiochip_remove(&data->mcp[addr]->chip);
 397                 if (tmp < 0) {
 398                         dev_err(&spi->dev, "%s --> %d\n", "remove", tmp);
 399                         status = tmp;
 400                 }
 401         }
 402         if (status == 0)
 403                 kfree(data);
 404         return status;
 405 }
 406
 407 static struct spi_driver mcp23s08_driver = {
 408         .probe          = mcp23s08_probe,
 409         .remove         = mcp23s08_remove,
 410         .driver = {
 411                 .name   = "mcp23s08",
 412                 .owner  = THIS_MODULE,
 413         },
 414 };
 415
 416 /*----------------------------------------------------------------------*/
 417
 418 static int __init mcp23s08_init(void)
 419 {
 420         return spi_register_driver(&mcp23s08_driver);
 421 }
 422 /* register after spi postcore initcall and before
 423  * subsys initcalls that may rely on these GPIOs
 424  */
 425 subsys_initcall(mcp23s08_init);
 426
 427 static void __exit mcp23s08_exit(void)
 428 {
 429         spi_unregister_driver(&mcp23s08_driver);
 430 }
 431 module_exit(mcp23s08_exit);
 432
 433 MODULE_LICENSE("GPL");
 434 MODULE_ALIAS("spi:mcp23s08");