drivers/gpio/gpio-max732x.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  MAX732x I2C Port Expander with 8/16 I/O
   4  *
   5  *  Copyright (C) 2007 Marvell International Ltd.
   6  *  Copyright (C) 2008 Jack Ren <jack.ren@marvell.com>
   7  *  Copyright (C) 2008 Eric Miao <eric.miao@marvell.com>
   8  *  Copyright (C) 2015 Linus Walleij <linus.walleij@linaro.org>
   9  *
  10  *  Derived from drivers/gpio/pca953x.c
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15 #include <linux/slab.h>
  16 #include <linux/string.h>
  17 #include <linux/gpio/driver.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/i2c.h>
  20 #include <linux/platform_data/max732x.h>
  21
  22 /*
  23  * Each port of MAX732x (including MAX7319) falls into one of the
  24  * following three types:
  25  *
  26  *   - Push Pull Output
  27  *   - Input
  28  *   - Open Drain I/O
  29  *
  30  * designated by 'O', 'I' and 'P' individually according to MAXIM's
  31  * datasheets. 'I' and 'P' ports are interrupt capables, some with
  32  * a dedicated interrupt mask.
  33  *
  34  * There are two groups of I/O ports, each group usually includes
  35  * up to 8 I/O ports, and is accessed by a specific I2C address:
  36  *
  37  *   - Group A : by I2C address 0b'110xxxx
  38  *   - Group B : by I2C address 0b'101xxxx
  39  *
  40  * where 'xxxx' is decided by the connections of pin AD2/AD0.  The
  41  * address used also affects the initial state of output signals.
  42  *
  43  * Within each group of ports, there are five known combinations of
  44  * I/O ports: 4I4O, 4P4O, 8I, 8P, 8O, see the definitions below for
  45  * the detailed organization of these ports. Only Goup A is interrupt
  46  * capable.
  47  *
  48  * GPIO numbers start from 'gpio_base + 0' to 'gpio_base + 8/16',
  49  * and GPIOs from GROUP_A are numbered before those from GROUP_B
  50  * (if there are two groups).
  51  *
  52  * NOTE: MAX7328/MAX7329 are drop-in replacements for PCF8574/a, so
  53  * they are not supported by this driver.
  54  */
  55
  56 #define PORT_NONE       0x0     /* '/' No Port */
  57 #define PORT_OUTPUT     0x1     /* 'O' Push-Pull, Output Only */
  58 #define PORT_INPUT      0x2     /* 'I' Input Only */
  59 #define PORT_OPENDRAIN  0x3     /* 'P' Open-Drain, I/O */
  60
  61 #define IO_4I4O         0x5AA5  /* O7 O6 I5 I4 I3 I2 O1 O0 */
  62 #define IO_4P4O         0x5FF5  /* O7 O6 P5 P4 P3 P2 O1 O0 */
  63 #define IO_8I           0xAAAA  /* I7 I6 I5 I4 I3 I2 I1 I0 */
  64 #define IO_8P           0xFFFF  /* P7 P6 P5 P4 P3 P2 P1 P0 */
  65 #define IO_8O           0x5555  /* O7 O6 O5 O4 O3 O2 O1 O0 */
  66
  67 #define GROUP_A(x)      ((x) & 0xffff)  /* I2C Addr: 0b'110xxxx */
  68 #define GROUP_B(x)      ((x) << 16)     /* I2C Addr: 0b'101xxxx */
  69
  70 #define INT_NONE        0x0     /* No interrupt capability */
  71 #define INT_NO_MASK     0x1     /* Has interrupts, no mask */
  72 #define INT_INDEP_MASK  0x2     /* Has interrupts, independent mask */
  73 #define INT_MERGED_MASK 0x3     /* Has interrupts, merged mask */
  74
  75 #define INT_CAPS(x)     (((uint64_t)(x)) << 32)
  76
  77 enum {
  78         MAX7319,
  79         MAX7320,
  80         MAX7321,
  81         MAX7322,
  82         MAX7323,
  83         MAX7324,
  84         MAX7325,
  85         MAX7326,
  86         MAX7327,
  87 };
  88
  89 static uint64_t max732x_features[] = {
  90         [MAX7319] = GROUP_A(IO_8I) | INT_CAPS(INT_MERGED_MASK),
  91         [MAX7320] = GROUP_B(IO_8O),
  92         [MAX7321] = GROUP_A(IO_8P) | INT_CAPS(INT_NO_MASK),
  93         [MAX7322] = GROUP_A(IO_4I4O) | INT_CAPS(INT_MERGED_MASK),
  94         [MAX7323] = GROUP_A(IO_4P4O) | INT_CAPS(INT_INDEP_MASK),
  95         [MAX7324] = GROUP_A(IO_8I) | GROUP_B(IO_8O) | INT_CAPS(INT_MERGED_MASK),
  96         [MAX7325] = GROUP_A(IO_8P) | GROUP_B(IO_8O) | INT_CAPS(INT_NO_MASK),
  97         [MAX7326] = GROUP_A(IO_4I4O) | GROUP_B(IO_8O) | INT_CAPS(INT_MERGED_MASK),
  98         [MAX7327] = GROUP_A(IO_4P4O) | GROUP_B(IO_8O) | INT_CAPS(INT_NO_MASK),
  99 };
 100
 101 static const struct i2c_device_id max732x_id[] = {
 102         { "max7319", MAX7319 },
 103         { "max7320", MAX7320 },
 104         { "max7321", MAX7321 },
 105         { "max7322", MAX7322 },
 106         { "max7323", MAX7323 },
 107         { "max7324", MAX7324 },
 108         { "max7325", MAX7325 },
 109         { "max7326", MAX7326 },
 110         { "max7327", MAX7327 },
 111         { },
 112 };
 113 MODULE_DEVICE_TABLE(i2c, max732x_id);
 114
 115 static const struct of_device_id max732x_of_table[] = {
 116         { .compatible = "maxim,max7319" },
 117         { .compatible = "maxim,max7320" },
 118         { .compatible = "maxim,max7321" },
 119         { .compatible = "maxim,max7322" },
 120         { .compatible = "maxim,max7323" },
 121         { .compatible = "maxim,max7324" },
 122         { .compatible = "maxim,max7325" },
 123         { .compatible = "maxim,max7326" },
 124         { .compatible = "maxim,max7327" },
 125         { }
 126 };
 127 MODULE_DEVICE_TABLE(of, max732x_of_table);
 128
 129 struct max732x_chip {
 130         struct gpio_chip gpio_chip;
 131
 132         struct i2c_client *client;      /* "main" client */
 133         struct i2c_client *client_dummy;
 134         struct i2c_client *client_group_a;
 135         struct i2c_client *client_group_b;
 136
 137         unsigned int    mask_group_a;
 138         unsigned int    dir_input;
 139         unsigned int    dir_output;
 140
 141         struct mutex    lock;
 142         uint8_t         reg_out[2];
 143
 144 #ifdef CONFIG_GPIO_MAX732X_IRQ
 145         struct mutex            irq_lock;
 146         uint8_t                 irq_mask;
 147         uint8_t                 irq_mask_cur;
 148         uint8_t                 irq_trig_raise;
 149         uint8_t                 irq_trig_fall;
 150         uint8_t                 irq_features;
 151 #endif
 152 };
 153
 154 static int max732x_writeb(struct max732x_chip *chip, int group_a, uint8_t val)
 155 {
 156         struct i2c_client *client;
 157         int ret;
 158
 159         client = group_a ? chip->client_group_a : chip->client_group_b;
 160         ret = i2c_smbus_write_byte(client, val);
 161         if (ret < 0) {
 162                 dev_err(&client->dev, "failed writing\n");
 163                 return ret;
 164         }
 165
 166         return 0;
 167 }
 168
 169 static int max732x_readb(struct max732x_chip *chip, int group_a, uint8_t *val)
 170 {
 171         struct i2c_client *client;
 172         int ret;
 173
 174         client = group_a ? chip->client_group_a : chip->client_group_b;
 175         ret = i2c_smbus_read_byte(client);
 176         if (ret < 0) {
 177                 dev_err(&client->dev, "failed reading\n");
 178                 return ret;
 179         }
 180
 181         *val = (uint8_t)ret;
 182         return 0;
 183 }
 184
 185 static inline int is_group_a(struct max732x_chip *chip, unsigned off)
 186 {
 187         return (1u << off) & chip->mask_group_a;
 188 }
 189
 190 static int max732x_gpio_get_value(struct gpio_chip *gc, unsigned off)
 191 {
 192         struct max732x_chip *chip = gpiochip_get_data(gc);
 193         uint8_t reg_val;
 194         int ret;
 195
 196         ret = max732x_readb(chip, is_group_a(chip, off), &reg_val);
 197         if (ret < 0)
 198                 return ret;
 199
 200         return !!(reg_val & (1u << (off & 0x7)));
 201 }
 202
 203 static void max732x_gpio_set_mask(struct gpio_chip *gc, unsigned off, int mask,
 204                                   int val)
 205 {
 206         struct max732x_chip *chip = gpiochip_get_data(gc);
 207         uint8_t reg_out;
 208         int ret;
 209
 210         mutex_lock(&chip->lock);
 211
 212         reg_out = (off > 7) ? chip->reg_out[1] : chip->reg_out[0];
 213         reg_out = (reg_out & ~mask) | (val & mask);
 214
 215         ret = max732x_writeb(chip, is_group_a(chip, off), reg_out);
 216         if (ret < 0)
 217                 goto out;
 218
 219         /* update the shadow register then */
 220         if (off > 7)
 221                 chip->reg_out[1] = reg_out;
 222         else
 223                 chip->reg_out[0] = reg_out;
 224 out:
 225         mutex_unlock(&chip->lock);
 226 }
 227
 228 static void max732x_gpio_set_value(struct gpio_chip *gc, unsigned off, int val)
 229 {
 230         unsigned base = off & ~0x7;
 231         uint8_t mask = 1u << (off & 0x7);
 232
 233         max732x_gpio_set_mask(gc, base, mask, val << (off & 0x7));
 234 }
 235
 236 static void max732x_gpio_set_multiple(struct gpio_chip *gc,
 237                                       unsigned long *mask, unsigned long *bits)
 238 {
 239         unsigned mask_lo = mask[0] & 0xff;
 240         unsigned mask_hi = (mask[0] >> 8) & 0xff;
 241
 242         if (mask_lo)
 243                 max732x_gpio_set_mask(gc, 0, mask_lo, bits[0] & 0xff);
 244         if (mask_hi)
 245                 max732x_gpio_set_mask(gc, 8, mask_hi, (bits[0] >> 8) & 0xff);
 246 }
 247
 248 static int max732x_gpio_direction_input(struct gpio_chip *gc, unsigned off)
 249 {
 250         struct max732x_chip *chip = gpiochip_get_data(gc);
 251         unsigned int mask = 1u << off;
 252
 253         if ((mask & chip->dir_input) == 0) {
 254                 dev_dbg(&chip->client->dev, "%s port %d is output only\n",
 255                         chip->client->name, off);
 256                 return -EACCES;
 257         }
 258
 259         /*
 260          * Open-drain pins must be set to high impedance (which is
 261          * equivalent to output-high) to be turned into an input.
 262          */
 263         if ((mask & chip->dir_output))
 264                 max732x_gpio_set_value(gc, off, 1);
 265
 266         return 0;
 267 }
 268
 269 static int max732x_gpio_direction_output(struct gpio_chip *gc,
 270                 unsigned off, int val)
 271 {
 272         struct max732x_chip *chip = gpiochip_get_data(gc);
 273         unsigned int mask = 1u << off;
 274
 275         if ((mask & chip->dir_output) == 0) {
 276                 dev_dbg(&chip->client->dev, "%s port %d is input only\n",
 277                         chip->client->name, off);
 278                 return -EACCES;
 279         }
 280
 281         max732x_gpio_set_value(gc, off, val);
 282         return 0;
 283 }
 284
 285 #ifdef CONFIG_GPIO_MAX732X_IRQ
 286 static int max732x_writew(struct max732x_chip *chip, uint16_t val)
 287 {
 288         int ret;
 289
 290         val = cpu_to_le16(val);
 291
 292         ret = i2c_master_send(chip->client_group_a, (char *)&val, 2);
 293         if (ret < 0) {
 294                 dev_err(&chip->client_group_a->dev, "failed writing\n");
 295                 return ret;
 296         }
 297
 298         return 0;
 299 }
 300
 301 static int max732x_readw(struct max732x_chip *chip, uint16_t *val)
 302 {
 303         int ret;
 304
 305         ret = i2c_master_recv(chip->client_group_a, (char *)val, 2);
 306         if (ret < 0) {
 307                 dev_err(&chip->client_group_a->dev, "failed reading\n");
 308                 return ret;
 309         }
 310
 311         *val = le16_to_cpu(*val);
 312         return 0;
 313 }
 314
 315 static void max732x_irq_update_mask(struct max732x_chip *chip)
 316 {
 317         uint16_t msg;
 318
 319         if (chip->irq_mask == chip->irq_mask_cur)
 320                 return;
 321
 322         chip->irq_mask = chip->irq_mask_cur;
 323
 324         if (chip->irq_features == INT_NO_MASK)
 325                 return;
 326
 327         mutex_lock(&chip->lock);
 328
 329         switch (chip->irq_features) {
 330         case INT_INDEP_MASK:
 331                 msg = (chip->irq_mask << 8) | chip->reg_out[0];
 332                 max732x_writew(chip, msg);
 333                 break;
 334
 335         case INT_MERGED_MASK:
 336                 msg = chip->irq_mask | chip->reg_out[0];
 337                 max732x_writeb(chip, 1, (uint8_t)msg);
 338                 break;
 339         }
 340
 341         mutex_unlock(&chip->lock);
 342 }
 343
 344 static void max732x_irq_mask(struct irq_data *d)
 345 {
 346         struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
 347         struct max732x_chip *chip = gpiochip_get_data(gc);
 348
 349         chip->irq_mask_cur &= ~(1 << d->hwirq);
 350         gpiochip_disable_irq(gc, irqd_to_hwirq(d));
 351 }
 352
 353 static void max732x_irq_unmask(struct irq_data *d)
 354 {
 355         struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
 356         struct max732x_chip *chip = gpiochip_get_data(gc);
 357
 358         gpiochip_enable_irq(gc, irqd_to_hwirq(d));
 359         chip->irq_mask_cur |= 1 << d->hwirq;
 360 }
 361
 362 static void max732x_irq_bus_lock(struct irq_data *d)
 363 {
 364         struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
 365         struct max732x_chip *chip = gpiochip_get_data(gc);
 366
 367         mutex_lock(&chip->irq_lock);
 368         chip->irq_mask_cur = chip->irq_mask;
 369 }
 370
 371 static void max732x_irq_bus_sync_unlock(struct irq_data *d)
 372 {
 373         struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
 374         struct max732x_chip *chip = gpiochip_get_data(gc);
 375         uint16_t new_irqs;
 376         uint16_t level;
 377
 378         max732x_irq_update_mask(chip);
 379
 380         new_irqs = chip->irq_trig_fall | chip->irq_trig_raise;
 381         while (new_irqs) {
 382                 level = __ffs(new_irqs);
 383                 max732x_gpio_direction_input(&chip->gpio_chip, level);
 384                 new_irqs &= ~(1 << level);
 385         }
 386
 387         mutex_unlock(&chip->irq_lock);
 388 }
 389
 390 static int max732x_irq_set_type(struct irq_data *d, unsigned int type)
 391 {
 392         struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
 393         struct max732x_chip *chip = gpiochip_get_data(gc);
 394         uint16_t off = d->hwirq;
 395         uint16_t mask = 1 << off;
 396
 397         if (!(mask & chip->dir_input)) {
 398                 dev_dbg(&chip->client->dev, "%s port %d is output only\n",
 399                         chip->client->name, off);
 400                 return -EACCES;
 401         }
 402
 403         if (!(type & IRQ_TYPE_EDGE_BOTH)) {
 404                 dev_err(&chip->client->dev, "irq %d: unsupported type %d\n",
 405                         d->irq, type);
 406                 return -EINVAL;
 407         }
 408
 409         if (type & IRQ_TYPE_EDGE_FALLING)
 410                 chip->irq_trig_fall |= mask;
 411         else
 412                 chip->irq_trig_fall &= ~mask;
 413
 414         if (type & IRQ_TYPE_EDGE_RISING)
 415                 chip->irq_trig_raise |= mask;
 416         else
 417                 chip->irq_trig_raise &= ~mask;
 418
 419         return 0;
 420 }
 421
 422 static int max732x_irq_set_wake(struct irq_data *data, unsigned int on)
 423 {
 424         struct max732x_chip *chip = irq_data_get_irq_chip_data(data);
 425
 426         irq_set_irq_wake(chip->client->irq, on);
 427         return 0;
 428 }
 429
 430 static const struct irq_chip max732x_irq_chip = {
 431         .name                   = "max732x",
 432         .irq_mask               = max732x_irq_mask,
 433         .irq_unmask             = max732x_irq_unmask,
 434         .irq_bus_lock           = max732x_irq_bus_lock,
 435         .irq_bus_sync_unlock    = max732x_irq_bus_sync_unlock,
 436         .irq_set_type           = max732x_irq_set_type,
 437         .irq_set_wake           = max732x_irq_set_wake,
 438         .flags                  = IRQCHIP_IMMUTABLE,
 439          GPIOCHIP_IRQ_RESOURCE_HELPERS,
 440 };
 441
 442 static uint8_t max732x_irq_pending(struct max732x_chip *chip)
 443 {
 444         uint8_t cur_stat;
 445         uint8_t old_stat;
 446         uint8_t trigger;
 447         uint8_t pending;
 448         uint16_t status;
 449         int ret;
 450
 451         ret = max732x_readw(chip, &status);
 452         if (ret)
 453                 return 0;
 454
 455         trigger = status >> 8;
 456         trigger &= chip->irq_mask;
 457
 458         if (!trigger)
 459                 return 0;
 460
 461         cur_stat = status & 0xFF;
 462         cur_stat &= chip->irq_mask;
 463
 464         old_stat = cur_stat ^ trigger;
 465
 466         pending = (old_stat & chip->irq_trig_fall) |
 467                   (cur_stat & chip->irq_trig_raise);
 468         pending &= trigger;
 469
 470         return pending;
 471 }
 472
 473 static irqreturn_t max732x_irq_handler(int irq, void *devid)
 474 {
 475         struct max732x_chip *chip = devid;
 476         uint8_t pending;
 477         uint8_t level;
 478
 479         pending = max732x_irq_pending(chip);
 480
 481         if (!pending)
 482                 return IRQ_HANDLED;
 483
 484         do {
 485                 level = __ffs(pending);
 486                 handle_nested_irq(irq_find_mapping(chip->gpio_chip.irq.domain,
 487                                                    level));
 488
 489                 pending &= ~(1 << level);
 490         } while (pending);
 491
 492         return IRQ_HANDLED;
 493 }
 494
 495 static int max732x_irq_setup(struct max732x_chip *chip,
 496                              const struct i2c_device_id *id)
 497 {
 498         struct i2c_client *client = chip->client;
 499         int has_irq = max732x_features[id->driver_data] >> 32;
 500         int irq_base = 0;
 501         int ret;
 502
 503         if (client->irq && has_irq != INT_NONE) {
 504                 struct gpio_irq_chip *girq;
 505
 506                 chip->irq_features = has_irq;
 507                 mutex_init(&chip->irq_lock);
 508
 509                 ret = devm_request_threaded_irq(&client->dev, client->irq,
 510                                 NULL, max732x_irq_handler, IRQF_ONESHOT |
 511                                 IRQF_TRIGGER_FALLING | IRQF_SHARED,
 512                                 dev_name(&client->dev), chip);
 513                 if (ret) {
 514                         dev_err(&client->dev, "failed to request irq %d\n",
 515                                 client->irq);
 516                         return ret;
 517                 }
 518
 519                 girq = &chip->gpio_chip.irq;
 520                 gpio_irq_chip_set_chip(girq, &max732x_irq_chip);
 521                 /* This will let us handle the parent IRQ in the driver */
 522                 girq->parent_handler = NULL;
 523                 girq->num_parents = 0;
 524                 girq->parents = NULL;
 525                 girq->default_type = IRQ_TYPE_NONE;
 526                 girq->handler = handle_simple_irq;
 527                 girq->threaded = true;
 528                 girq->first = irq_base; /* FIXME: get rid of this */
 529         }
 530
 531         return 0;
 532 }
 533
 534 #else /* CONFIG_GPIO_MAX732X_IRQ */
 535 static int max732x_irq_setup(struct max732x_chip *chip,
 536                              const struct i2c_device_id *id)
 537 {
 538         struct i2c_client *client = chip->client;
 539         int has_irq = max732x_features[id->driver_data] >> 32;
 540
 541         if (client->irq && has_irq != INT_NONE)
 542                 dev_warn(&client->dev, "interrupt support not compiled in\n");
 543
 544         return 0;
 545 }
 546 #endif
 547
 548 static int max732x_setup_gpio(struct max732x_chip *chip,
 549                                         const struct i2c_device_id *id,
 550                                         unsigned gpio_start)
 551 {
 552         struct gpio_chip *gc = &chip->gpio_chip;
 553         uint32_t id_data = (uint32_t)max732x_features[id->driver_data];
 554         int i, port = 0;
 555
 556         for (i = 0; i < 16; i++, id_data >>= 2) {
 557                 unsigned int mask = 1 << port;
 558
 559                 switch (id_data & 0x3) {
 560                 case PORT_OUTPUT:
 561                         chip->dir_output |= mask;
 562                         break;
 563                 case PORT_INPUT:
 564                         chip->dir_input |= mask;
 565                         break;
 566                 case PORT_OPENDRAIN:
 567                         chip->dir_output |= mask;
 568                         chip->dir_input |= mask;
 569                         break;
 570                 default:
 571                         continue;
 572                 }
 573
 574                 if (i < 8)
 575                         chip->mask_group_a |= mask;
 576                 port++;
 577         }
 578
 579         if (chip->dir_input)
 580                 gc->direction_input = max732x_gpio_direction_input;
 581         if (chip->dir_output) {
 582                 gc->direction_output = max732x_gpio_direction_output;
 583                 gc->set = max732x_gpio_set_value;
 584                 gc->set_multiple = max732x_gpio_set_multiple;
 585         }
 586         gc->get = max732x_gpio_get_value;
 587         gc->can_sleep = true;
 588
 589         gc->base = gpio_start;
 590         gc->ngpio = port;
 591         gc->label = chip->client->name;
 592         gc->parent = &chip->client->dev;
 593         gc->owner = THIS_MODULE;
 594
 595         return port;
 596 }
 597
 598 static struct max732x_platform_data *of_gpio_max732x(struct device *dev)
 599 {
 600         struct max732x_platform_data *pdata;
 601
 602         pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
 603         if (!pdata)
 604                 return NULL;
 605
 606         pdata->gpio_base = -1;
 607
 608         return pdata;
 609 }
 610
 611 static int max732x_probe(struct i2c_client *client)
 612 {
 613         const struct i2c_device_id *id = i2c_client_get_device_id(client);
 614         struct max732x_platform_data *pdata;
 615         struct device_node *node;
 616         struct max732x_chip *chip;
 617         struct i2c_client *c;
 618         uint16_t addr_a, addr_b;
 619         int ret, nr_port;
 620
 621         pdata = dev_get_platdata(&client->dev);
 622         node = client->dev.of_node;
 623
 624         if (!pdata && node)
 625                 pdata = of_gpio_max732x(&client->dev);
 626
 627         if (!pdata) {
 628                 dev_dbg(&client->dev, "no platform data\n");
 629                 return -EINVAL;
 630         }
 631
 632         chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
 633         if (chip == NULL)
 634                 return -ENOMEM;
 635         chip->client = client;
 636
 637         nr_port = max732x_setup_gpio(chip, id, pdata->gpio_base);
 638         chip->gpio_chip.parent = &client->dev;
 639
 640         addr_a = (client->addr & 0x0f) | 0x60;
 641         addr_b = (client->addr & 0x0f) | 0x50;
 642
 643         switch (client->addr & 0x70) {
 644         case 0x60:
 645                 chip->client_group_a = client;
 646                 if (nr_port > 8) {
 647                         c = devm_i2c_new_dummy_device(&client->dev,
 648                                                       client->adapter, addr_b);
 649                         if (IS_ERR(c)) {
 650                                 dev_err(&client->dev,
 651                                         "Failed to allocate I2C device\n");
 652                                 return PTR_ERR(c);
 653                         }
 654                         chip->client_group_b = chip->client_dummy = c;
 655                 }
 656                 break;
 657         case 0x50:
 658                 chip->client_group_b = client;
 659                 if (nr_port > 8) {
 660                         c = devm_i2c_new_dummy_device(&client->dev,
 661                                                       client->adapter, addr_a);
 662                         if (IS_ERR(c)) {
 663                                 dev_err(&client->dev,
 664                                         "Failed to allocate I2C device\n");
 665                                 return PTR_ERR(c);
 666                         }
 667                         chip->client_group_a = chip->client_dummy = c;
 668                 }
 669                 break;
 670         default:
 671                 dev_err(&client->dev, "invalid I2C address specified %02x\n",
 672                                 client->addr);
 673                 return -EINVAL;
 674         }
 675
 676         if (nr_port > 8 && !chip->client_dummy) {
 677                 dev_err(&client->dev,
 678                         "Failed to allocate second group I2C device\n");
 679                 return -ENODEV;
 680         }
 681
 682         mutex_init(&chip->lock);
 683
 684         ret = max732x_readb(chip, is_group_a(chip, 0), &chip->reg_out[0]);
 685         if (ret)
 686                 return ret;
 687         if (nr_port > 8) {
 688                 ret = max732x_readb(chip, is_group_a(chip, 8), &chip->reg_out[1]);
 689                 if (ret)
 690                         return ret;
 691         }
 692
 693         ret = max732x_irq_setup(chip, id);
 694         if (ret)
 695                 return ret;
 696
 697         ret = devm_gpiochip_add_data(&client->dev, &chip->gpio_chip, chip);
 698         if (ret)
 699                 return ret;
 700
 701         i2c_set_clientdata(client, chip);
 702         return 0;
 703 }
 704
 705 static struct i2c_driver max732x_driver = {
 706         .driver = {
 707                 .name           = "max732x",
 708                 .of_match_table = max732x_of_table,
 709         },
 710         .probe          = max732x_probe,
 711         .id_table       = max732x_id,
 712 };
 713
 714 static int __init max732x_init(void)
 715 {
 716         return i2c_add_driver(&max732x_driver);
 717 }
 718 /* register after i2c postcore initcall and before
 719  * subsys initcalls that may rely on these GPIOs
 720  */
 721 subsys_initcall(max732x_init);
 722
 723 static void __exit max732x_exit(void)
 724 {
 725         i2c_del_driver(&max732x_driver);
 726 }
 727 module_exit(max732x_exit);
 728
 729 MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>");
 730 MODULE_DESCRIPTION("GPIO expander driver for MAX732X");
 731 MODULE_LICENSE("GPL");