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         /* lock protects the cached values */
  44         struct mutex            lock;
  45         u8                      cache[11];
  46
  47         struct gpio_chip        chip;
  48
  49         struct work_struct      work;
  50 };
  51
  52 static int mcp23s08_read(struct mcp23s08 *mcp, unsigned reg)
  53 {
  54         u8      tx[2], rx[1];
  55         int     status;
  56
  57         tx[0] = mcp->addr | 0x01;
  58         tx[1] = reg;
  59         status = spi_write_then_read(mcp->spi, tx, sizeof tx, rx, sizeof rx);
  60         return (status < 0) ? status : rx[0];
  61 }
  62
  63 static int mcp23s08_write(struct mcp23s08 *mcp, unsigned reg, u8 val)
  64 {
  65         u8      tx[3];
  66
  67         tx[0] = mcp->addr;
  68         tx[1] = reg;
  69         tx[2] = val;
  70         return spi_write_then_read(mcp->spi, tx, sizeof tx, NULL, 0);
  71 }
  72
  73 static int
  74 mcp23s08_read_regs(struct mcp23s08 *mcp, unsigned reg, u8 *vals, unsigned n)
  75 {
  76         u8      tx[2];
  77
  78         if ((n + reg) > sizeof mcp->cache)
  79                 return -EINVAL;
  80         tx[0] = mcp->addr | 0x01;
  81         tx[1] = reg;
  82         return spi_write_then_read(mcp->spi, tx, sizeof tx, vals, n);
  83 }
  84
  85 /*----------------------------------------------------------------------*/
  86
  87 static int mcp23s08_direction_input(struct gpio_chip *chip, unsigned offset)
  88 {
  89         struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
  90         int status;
  91
  92         mutex_lock(&mcp->lock);
  93         mcp->cache[MCP_IODIR] |= (1 << offset);
  94         status = mcp23s08_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
  95         mutex_unlock(&mcp->lock);
  96         return status;
  97 }
  98
  99 static int mcp23s08_get(struct gpio_chip *chip, unsigned offset)
 100 {
 101         struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
 102         int status;
 103
 104         mutex_lock(&mcp->lock);
 105
 106         /* REVISIT reading this clears any IRQ ... */
 107         status = mcp23s08_read(mcp, MCP_GPIO);
 108         if (status < 0)
 109                 status = 0;
 110         else {
 111                 mcp->cache[MCP_GPIO] = status;
 112                 status = !!(status & (1 << offset));
 113         }
 114         mutex_unlock(&mcp->lock);
 115         return status;
 116 }
 117
 118 static int __mcp23s08_set(struct mcp23s08 *mcp, unsigned mask, int value)
 119 {
 120         u8 olat = mcp->cache[MCP_OLAT];
 121
 122         if (value)
 123                 olat |= mask;
 124         else
 125                 olat &= ~mask;
 126         mcp->cache[MCP_OLAT] = olat;
 127         return mcp23s08_write(mcp, MCP_OLAT, olat);
 128 }
 129
 130 static void mcp23s08_set(struct gpio_chip *chip, unsigned offset, int value)
 131 {
 132         struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
 133         u8 mask = 1 << offset;
 134
 135         mutex_lock(&mcp->lock);
 136         __mcp23s08_set(mcp, mask, value);
 137         mutex_unlock(&mcp->lock);
 138 }
 139
 140 static int
 141 mcp23s08_direction_output(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         int status;
 146
 147         mutex_lock(&mcp->lock);
 148         status = __mcp23s08_set(mcp, mask, value);
 149         if (status == 0) {
 150                 mcp->cache[MCP_IODIR] &= ~mask;
 151                 status = mcp23s08_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
 152         }
 153         mutex_unlock(&mcp->lock);
 154         return status;
 155 }
 156
 157 /*----------------------------------------------------------------------*/
 158
 159 #ifdef CONFIG_DEBUG_FS
 160
 161 #include <linux/seq_file.h>
 162
 163 /*
 164  * This shows more info than the generic gpio dump code:
 165  * pullups, deglitching, open drain drive.
 166  */
 167 static void mcp23s08_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 168 {
 169         struct mcp23s08 *mcp;
 170         char            bank;
 171         unsigned        t;
 172         unsigned        mask;
 173
 174         mcp = container_of(chip, struct mcp23s08, chip);
 175
 176         /* NOTE: we only handle one bank for now ... */
 177         bank = '0' + ((mcp->addr >> 1) & 0x3);
 178
 179         mutex_lock(&mcp->lock);
 180         t = mcp23s08_read_regs(mcp, 0, mcp->cache, sizeof mcp->cache);
 181         if (t < 0) {
 182                 seq_printf(s, " I/O ERROR %d\n", t);
 183                 goto done;
 184         }
 185
 186         for (t = 0, mask = 1; t < 8; t++, mask <<= 1) {
 187                 const char      *label;
 188
 189                 label = gpiochip_is_requested(chip, t);
 190                 if (!label)
 191                         continue;
 192
 193                 seq_printf(s, " gpio-%-3d P%c.%d (%-12s) %s %s %s",
 194                         chip->base + t, bank, t, label,
 195                         (mcp->cache[MCP_IODIR] & mask) ? "in " : "out",
 196                         (mcp->cache[MCP_GPIO] & mask) ? "hi" : "lo",
 197                         (mcp->cache[MCP_GPPU] & mask) ? "  " : "up");
 198                 /* NOTE:  ignoring the irq-related registers */
 199                 seq_printf(s, "\n");
 200         }
 201 done:
 202         mutex_unlock(&mcp->lock);
 203 }
 204
 205 #else
 206 #define mcp23s08_dbg_show       NULL
 207 #endif
 208
 209 /*----------------------------------------------------------------------*/
 210
 211 static int mcp23s08_probe(struct spi_device *spi)
 212 {
 213         struct mcp23s08                 *mcp;
 214         struct mcp23s08_platform_data   *pdata;
 215         int                             status;
 216         int                             do_update = 0;
 217
 218         pdata = spi->dev.platform_data;
 219         if (!pdata || pdata->slave > 3 || !pdata->base)
 220                 return -ENODEV;
 221
 222         mcp = kzalloc(sizeof *mcp, GFP_KERNEL);
 223         if (!mcp)
 224                 return -ENOMEM;
 225
 226         mutex_init(&mcp->lock);
 227
 228         mcp->spi = spi;
 229         mcp->addr = 0x40 | (pdata->slave << 1);
 230
 231         mcp->chip.label = "mcp23s08",
 232
 233         mcp->chip.direction_input = mcp23s08_direction_input;
 234         mcp->chip.get = mcp23s08_get;
 235         mcp->chip.direction_output = mcp23s08_direction_output;
 236         mcp->chip.set = mcp23s08_set;
 237         mcp->chip.dbg_show = mcp23s08_dbg_show;
 238
 239         mcp->chip.base = pdata->base;
 240         mcp->chip.ngpio = 8;
 241         mcp->chip.can_sleep = 1;
 242         mcp->chip.owner = THIS_MODULE;
 243
 244         spi_set_drvdata(spi, mcp);
 245
 246         /* verify MCP_IOCON.SEQOP = 0, so sequential reads work */
 247         status = mcp23s08_read(mcp, MCP_IOCON);
 248         if (status < 0)
 249                 goto fail;
 250         if (status & IOCON_SEQOP) {
 251                 status &= ~IOCON_SEQOP;
 252                 status = mcp23s08_write(mcp, MCP_IOCON, (u8) status);
 253                 if (status < 0)
 254                         goto fail;
 255         }
 256
 257         /* configure ~100K pullups */
 258         status = mcp23s08_write(mcp, MCP_GPPU, pdata->pullups);
 259         if (status < 0)
 260                 goto fail;
 261
 262         status = mcp23s08_read_regs(mcp, 0, mcp->cache, sizeof mcp->cache);
 263         if (status < 0)
 264                 goto fail;
 265
 266         /* disable inverter on input */
 267         if (mcp->cache[MCP_IPOL] != 0) {
 268                 mcp->cache[MCP_IPOL] = 0;
 269                 do_update = 1;
 270         }
 271
 272         /* disable irqs */
 273         if (mcp->cache[MCP_GPINTEN] != 0) {
 274                 mcp->cache[MCP_GPINTEN] = 0;
 275                 do_update = 1;
 276         }
 277
 278         if (do_update) {
 279                 u8 tx[4];
 280
 281                 tx[0] = mcp->addr;
 282                 tx[1] = MCP_IPOL;
 283                 memcpy(&tx[2], &mcp->cache[MCP_IPOL], sizeof(tx) - 2);
 284                 status = spi_write_then_read(mcp->spi, tx, sizeof tx, NULL, 0);
 285
 286                 /* FIXME check status... */
 287         }
 288
 289         status = gpiochip_add(&mcp->chip);
 290
 291         /* NOTE:  these chips have a relatively sane IRQ framework, with
 292          * per-signal masking and level/edge triggering.  It's not yet
 293          * handled here...
 294          */
 295
 296         if (pdata->setup) {
 297                 status = pdata->setup(spi, mcp->chip.base,
 298                                 mcp->chip.ngpio, pdata->context);
 299                 if (status < 0)
 300                         dev_dbg(&spi->dev, "setup --> %d\n", status);
 301         }
 302
 303         return 0;
 304
 305 fail:
 306         kfree(mcp);
 307         return status;
 308 }
 309
 310 static int mcp23s08_remove(struct spi_device *spi)
 311 {
 312         struct mcp23s08                 *mcp = spi_get_drvdata(spi);
 313         struct mcp23s08_platform_data   *pdata = spi->dev.platform_data;
 314         int                             status = 0;
 315
 316         if (pdata->teardown) {
 317                 status = pdata->teardown(spi,
 318                                 mcp->chip.base, mcp->chip.ngpio,
 319                                 pdata->context);
 320                 if (status < 0) {
 321                         dev_err(&spi->dev, "%s --> %d\n", "teardown", status);
 322                         return status;
 323                 }
 324         }
 325
 326         status = gpiochip_remove(&mcp->chip);
 327         if (status == 0)
 328                 kfree(mcp);
 329         else
 330                 dev_err(&spi->dev, "%s --> %d\n", "remove", status);
 331         return status;
 332 }
 333
 334 static struct spi_driver mcp23s08_driver = {
 335         .probe          = mcp23s08_probe,
 336         .remove         = mcp23s08_remove,
 337         .driver = {
 338                 .name   = "mcp23s08",
 339                 .owner  = THIS_MODULE,
 340         },
 341 };
 342
 343 /*----------------------------------------------------------------------*/
 344
 345 static int __init mcp23s08_init(void)
 346 {
 347         return spi_register_driver(&mcp23s08_driver);
 348 }
 349 module_init(mcp23s08_init);
 350
 351 static void __exit mcp23s08_exit(void)
 352 {
 353         spi_unregister_driver(&mcp23s08_driver);
 354 }
 355 module_exit(mcp23s08_exit);
 356
 357 MODULE_LICENSE("GPL");
 358