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