root/drivers/gpio/gpio-twl4030.c

DEFINITIONS

1. gpio_twl4030_write
2. gpio_twl4030_read
3. twl4030_led_set_value
4. twl4030_set_gpio_direction
5. twl4030_get_gpio_direction
6. twl4030_set_gpio_dataout
7. twl4030_get_gpio_datain
8. twl_request
9. twl_free
10. twl_direction_in
11. twl_get
12. twl_set
13. twl_direction_out
14. twl_get_direction
15. twl_to_irq
16. gpio_twl4030_pulls
17. gpio_twl4030_debounce
18. of_gpio_twl4030
19. gpio_twl4030_probe
20. gpio_twl4030_remove
21. gpio_twl4030_init
22. gpio_twl4030_exit

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Access to GPIOs on TWL4030/TPS659x0 chips
   4  *
   5  * Copyright (C) 2006-2007 Texas Instruments, Inc.
   6  * Copyright (C) 2006 MontaVista Software, Inc.
   7  *
   8  * Code re-arranged and cleaned up by:
   9  *      Syed Mohammed Khasim <x0khasim@ti.com>
  10  *
  11  * Initial Code:
  12  *      Andy Lowe / Nishanth Menon
  13  */
  14 
  15 #include <linux/module.h>
  16 #include <linux/init.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/kthread.h>
  19 #include <linux/irq.h>
  20 #include <linux/gpio/driver.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/of.h>
  23 #include <linux/irqdomain.h>
  24 
  25 #include <linux/mfd/twl.h>
  26 
  27 /*
  28  * The GPIO "subchip" supports 18 GPIOs which can be configured as
  29  * inputs or outputs, with pullups or pulldowns on each pin.  Each
  30  * GPIO can trigger interrupts on either or both edges.
  31  *
  32  * GPIO interrupts can be fed to either of two IRQ lines; this is
  33  * intended to support multiple hosts.
  34  *
  35  * There are also two LED pins used sometimes as output-only GPIOs.
  36  */
  37 
  38 /* genirq interfaces are not available to modules */
  39 #ifdef MODULE
  40 #define is_module()     true
  41 #else
  42 #define is_module()     false
  43 #endif
  44 
  45 /* GPIO_CTRL Fields */
  46 #define MASK_GPIO_CTRL_GPIO0CD1         BIT(0)
  47 #define MASK_GPIO_CTRL_GPIO1CD2         BIT(1)
  48 #define MASK_GPIO_CTRL_GPIO_ON          BIT(2)
  49 
  50 /* Mask for GPIO registers when aggregated into a 32-bit integer */
  51 #define GPIO_32_MASK                    0x0003ffff
  52 
  53 struct gpio_twl4030_priv {
  54         struct gpio_chip gpio_chip;
  55         struct mutex mutex;
  56         int irq_base;
  57 
  58         /* Bitfields for state caching */
  59         unsigned int usage_count;
  60         unsigned int direction;
  61         unsigned int out_state;
  62 };
  63 
  64 /*----------------------------------------------------------------------*/
  65 
  66 /*
  67  * To configure TWL4030 GPIO module registers
  68  */
  69 static inline int gpio_twl4030_write(u8 address, u8 data)
  70 {
  71         return twl_i2c_write_u8(TWL4030_MODULE_GPIO, data, address);
  72 }
  73 
  74 /*----------------------------------------------------------------------*/
  75 
  76 /*
  77  * LED register offsets from TWL_MODULE_LED base
  78  * PWMs A and B are dedicated to LEDs A and B, respectively.
  79  */
  80 
  81 #define TWL4030_LED_LEDEN_REG   0x00
  82 #define TWL4030_PWMAON_REG      0x01
  83 #define TWL4030_PWMAOFF_REG     0x02
  84 #define TWL4030_PWMBON_REG      0x03
  85 #define TWL4030_PWMBOFF_REG     0x04
  86 
  87 /* LEDEN bits */
  88 #define LEDEN_LEDAON            BIT(0)
  89 #define LEDEN_LEDBON            BIT(1)
  90 #define LEDEN_LEDAEXT           BIT(2)
  91 #define LEDEN_LEDBEXT           BIT(3)
  92 #define LEDEN_LEDAPWM           BIT(4)
  93 #define LEDEN_LEDBPWM           BIT(5)
  94 #define LEDEN_PWM_LENGTHA       BIT(6)
  95 #define LEDEN_PWM_LENGTHB       BIT(7)
  96 
  97 #define PWMxON_LENGTH           BIT(7)
  98 
  99 /*----------------------------------------------------------------------*/
 100 
 101 /*
 102  * To read a TWL4030 GPIO module register
 103  */
 104 static inline int gpio_twl4030_read(u8 address)
 105 {
 106         u8 data;
 107         int ret = 0;
 108 
 109         ret = twl_i2c_read_u8(TWL4030_MODULE_GPIO, &data, address);
 110         return (ret < 0) ? ret : data;
 111 }
 112 
 113 /*----------------------------------------------------------------------*/
 114 
 115 static u8 cached_leden;
 116 
 117 /* The LED lines are open drain outputs ... a FET pulls to GND, so an
 118  * external pullup is needed.  We could also expose the integrated PWM
 119  * as a LED brightness control; we initialize it as "always on".
 120  */
 121 static void twl4030_led_set_value(int led, int value)
 122 {
 123         u8 mask = LEDEN_LEDAON | LEDEN_LEDAPWM;
 124 
 125         if (led)
 126                 mask <<= 1;
 127 
 128         if (value)
 129                 cached_leden &= ~mask;
 130         else
 131                 cached_leden |= mask;
 132 
 133         WARN_ON_ONCE(twl_i2c_write_u8(TWL4030_MODULE_LED, cached_leden,
 134                                       TWL4030_LED_LEDEN_REG));
 135 }
 136 
 137 static int twl4030_set_gpio_direction(int gpio, int is_input)
 138 {
 139         u8 d_bnk = gpio >> 3;
 140         u8 d_msk = BIT(gpio & 0x7);
 141         u8 reg = 0;
 142         u8 base = REG_GPIODATADIR1 + d_bnk;
 143         int ret = 0;
 144 
 145         ret = gpio_twl4030_read(base);
 146         if (ret >= 0) {
 147                 if (is_input)
 148                         reg = ret & ~d_msk;
 149                 else
 150                         reg = ret | d_msk;
 151 
 152                 ret = gpio_twl4030_write(base, reg);
 153         }
 154         return ret;
 155 }
 156 
 157 static int twl4030_get_gpio_direction(int gpio)
 158 {
 159         u8 d_bnk = gpio >> 3;
 160         u8 d_msk = BIT(gpio & 0x7);
 161         u8 base = REG_GPIODATADIR1 + d_bnk;
 162         int ret = 0;
 163 
 164         ret = gpio_twl4030_read(base);
 165         if (ret < 0)
 166                 return ret;
 167 
 168         /* 1 = output, but gpiolib semantics are inverse so invert */
 169         ret = !(ret & d_msk);
 170 
 171         return ret;
 172 }
 173 
 174 static int twl4030_set_gpio_dataout(int gpio, int enable)
 175 {
 176         u8 d_bnk = gpio >> 3;
 177         u8 d_msk = BIT(gpio & 0x7);
 178         u8 base = 0;
 179 
 180         if (enable)
 181                 base = REG_SETGPIODATAOUT1 + d_bnk;
 182         else
 183                 base = REG_CLEARGPIODATAOUT1 + d_bnk;
 184 
 185         return gpio_twl4030_write(base, d_msk);
 186 }
 187 
 188 static int twl4030_get_gpio_datain(int gpio)
 189 {
 190         u8 d_bnk = gpio >> 3;
 191         u8 d_off = gpio & 0x7;
 192         u8 base = 0;
 193         int ret = 0;
 194 
 195         base = REG_GPIODATAIN1 + d_bnk;
 196         ret = gpio_twl4030_read(base);
 197         if (ret > 0)
 198                 ret = (ret >> d_off) & 0x1;
 199 
 200         return ret;
 201 }
 202 
 203 /*----------------------------------------------------------------------*/
 204 
 205 static int twl_request(struct gpio_chip *chip, unsigned offset)
 206 {
 207         struct gpio_twl4030_priv *priv = gpiochip_get_data(chip);
 208         int status = 0;
 209 
 210         mutex_lock(&priv->mutex);
 211 
 212         /* Support the two LED outputs as output-only GPIOs. */
 213         if (offset >= TWL4030_GPIO_MAX) {
 214                 u8      ledclr_mask = LEDEN_LEDAON | LEDEN_LEDAEXT
 215                                 | LEDEN_LEDAPWM | LEDEN_PWM_LENGTHA;
 216                 u8      reg = TWL4030_PWMAON_REG;
 217 
 218                 offset -= TWL4030_GPIO_MAX;
 219                 if (offset) {
 220                         ledclr_mask <<= 1;
 221                         reg = TWL4030_PWMBON_REG;
 222                 }
 223 
 224                 /* initialize PWM to always-drive */
 225                 /* Configure PWM OFF register first */
 226                 status = twl_i2c_write_u8(TWL4030_MODULE_LED, 0x7f, reg + 1);
 227                 if (status < 0)
 228                         goto done;
 229 
 230                 /* Followed by PWM ON register */
 231                 status = twl_i2c_write_u8(TWL4030_MODULE_LED, 0x7f, reg);
 232                 if (status < 0)
 233                         goto done;
 234 
 235                 /* init LED to not-driven (high) */
 236                 status = twl_i2c_read_u8(TWL4030_MODULE_LED, &cached_leden,
 237                                          TWL4030_LED_LEDEN_REG);
 238                 if (status < 0)
 239                         goto done;
 240                 cached_leden &= ~ledclr_mask;
 241                 status = twl_i2c_write_u8(TWL4030_MODULE_LED, cached_leden,
 242                                           TWL4030_LED_LEDEN_REG);
 243                 if (status < 0)
 244                         goto done;
 245 
 246                 status = 0;
 247                 goto done;
 248         }
 249 
 250         /* on first use, turn GPIO module "on" */
 251         if (!priv->usage_count) {
 252                 struct twl4030_gpio_platform_data *pdata;
 253                 u8 value = MASK_GPIO_CTRL_GPIO_ON;
 254 
 255                 /* optionally have the first two GPIOs switch vMMC1
 256                  * and vMMC2 power supplies based on card presence.
 257                  */
 258                 pdata = dev_get_platdata(chip->parent);
 259                 if (pdata)
 260                         value |= pdata->mmc_cd & 0x03;
 261 
 262                 status = gpio_twl4030_write(REG_GPIO_CTRL, value);
 263         }
 264 
 265 done:
 266         if (!status)
 267                 priv->usage_count |= BIT(offset);
 268 
 269         mutex_unlock(&priv->mutex);
 270         return status;
 271 }
 272 
 273 static void twl_free(struct gpio_chip *chip, unsigned offset)
 274 {
 275         struct gpio_twl4030_priv *priv = gpiochip_get_data(chip);
 276 
 277         mutex_lock(&priv->mutex);
 278         if (offset >= TWL4030_GPIO_MAX) {
 279                 twl4030_led_set_value(offset - TWL4030_GPIO_MAX, 1);
 280                 goto out;
 281         }
 282 
 283         priv->usage_count &= ~BIT(offset);
 284 
 285         /* on last use, switch off GPIO module */
 286         if (!priv->usage_count)
 287                 gpio_twl4030_write(REG_GPIO_CTRL, 0x0);
 288 
 289 out:
 290         mutex_unlock(&priv->mutex);
 291 }
 292 
 293 static int twl_direction_in(struct gpio_chip *chip, unsigned offset)
 294 {
 295         struct gpio_twl4030_priv *priv = gpiochip_get_data(chip);
 296         int ret;
 297 
 298         mutex_lock(&priv->mutex);
 299         if (offset < TWL4030_GPIO_MAX)
 300                 ret = twl4030_set_gpio_direction(offset, 1);
 301         else
 302                 ret = -EINVAL;  /* LED outputs can't be set as input */
 303 
 304         if (!ret)
 305                 priv->direction &= ~BIT(offset);
 306 
 307         mutex_unlock(&priv->mutex);
 308 
 309         return ret;
 310 }
 311 
 312 static int twl_get(struct gpio_chip *chip, unsigned offset)
 313 {
 314         struct gpio_twl4030_priv *priv = gpiochip_get_data(chip);
 315         int ret;
 316         int status = 0;
 317 
 318         mutex_lock(&priv->mutex);
 319         if (!(priv->usage_count & BIT(offset))) {
 320                 ret = -EPERM;
 321                 goto out;
 322         }
 323 
 324         if (priv->direction & BIT(offset))
 325                 status = priv->out_state & BIT(offset);
 326         else
 327                 status = twl4030_get_gpio_datain(offset);
 328 
 329         ret = (status < 0) ? status : !!status;
 330 out:
 331         mutex_unlock(&priv->mutex);
 332         return ret;
 333 }
 334 
 335 static void twl_set(struct gpio_chip *chip, unsigned offset, int value)
 336 {
 337         struct gpio_twl4030_priv *priv = gpiochip_get_data(chip);
 338 
 339         mutex_lock(&priv->mutex);
 340         if (offset < TWL4030_GPIO_MAX)
 341                 twl4030_set_gpio_dataout(offset, value);
 342         else
 343                 twl4030_led_set_value(offset - TWL4030_GPIO_MAX, value);
 344 
 345         if (value)
 346                 priv->out_state |= BIT(offset);
 347         else
 348                 priv->out_state &= ~BIT(offset);
 349 
 350         mutex_unlock(&priv->mutex);
 351 }
 352 
 353 static int twl_direction_out(struct gpio_chip *chip, unsigned offset, int value)
 354 {
 355         struct gpio_twl4030_priv *priv = gpiochip_get_data(chip);
 356         int ret = 0;
 357 
 358         mutex_lock(&priv->mutex);
 359         if (offset < TWL4030_GPIO_MAX) {
 360                 ret = twl4030_set_gpio_direction(offset, 0);
 361                 if (ret) {
 362                         mutex_unlock(&priv->mutex);
 363                         return ret;
 364                 }
 365         }
 366 
 367         /*
 368          *  LED gpios i.e. offset >= TWL4030_GPIO_MAX are always output
 369          */
 370 
 371         priv->direction |= BIT(offset);
 372         mutex_unlock(&priv->mutex);
 373 
 374         twl_set(chip, offset, value);
 375 
 376         return ret;
 377 }
 378 
 379 static int twl_get_direction(struct gpio_chip *chip, unsigned offset)
 380 {
 381         struct gpio_twl4030_priv *priv = gpiochip_get_data(chip);
 382         /*
 383          * Default 0 = output
 384          * LED GPIOs >= TWL4030_GPIO_MAX are always output
 385          */
 386         int ret = 0;
 387 
 388         mutex_lock(&priv->mutex);
 389         if (offset < TWL4030_GPIO_MAX) {
 390                 ret = twl4030_get_gpio_direction(offset);
 391                 if (ret) {
 392                         mutex_unlock(&priv->mutex);
 393                         return ret;
 394                 }
 395         }
 396         mutex_unlock(&priv->mutex);
 397 
 398         return ret;
 399 }
 400 
 401 static int twl_to_irq(struct gpio_chip *chip, unsigned offset)
 402 {
 403         struct gpio_twl4030_priv *priv = gpiochip_get_data(chip);
 404 
 405         return (priv->irq_base && (offset < TWL4030_GPIO_MAX))
 406                 ? (priv->irq_base + offset)
 407                 : -EINVAL;
 408 }
 409 
 410 static const struct gpio_chip template_chip = {
 411         .label                  = "twl4030",
 412         .owner                  = THIS_MODULE,
 413         .request                = twl_request,
 414         .free                   = twl_free,
 415         .direction_input        = twl_direction_in,
 416         .direction_output       = twl_direction_out,
 417         .get_direction          = twl_get_direction,
 418         .get                    = twl_get,
 419         .set                    = twl_set,
 420         .to_irq                 = twl_to_irq,
 421         .can_sleep              = true,
 422 };
 423 
 424 /*----------------------------------------------------------------------*/
 425 
 426 static int gpio_twl4030_pulls(u32 ups, u32 downs)
 427 {
 428         u8              message[5];
 429         unsigned        i, gpio_bit;
 430 
 431         /* For most pins, a pulldown was enabled by default.
 432          * We should have data that's specific to this board.
 433          */
 434         for (gpio_bit = 1, i = 0; i < 5; i++) {
 435                 u8              bit_mask;
 436                 unsigned        j;
 437 
 438                 for (bit_mask = 0, j = 0; j < 8; j += 2, gpio_bit <<= 1) {
 439                         if (ups & gpio_bit)
 440                                 bit_mask |= 1 << (j + 1);
 441                         else if (downs & gpio_bit)
 442                                 bit_mask |= 1 << (j + 0);
 443                 }
 444                 message[i] = bit_mask;
 445         }
 446 
 447         return twl_i2c_write(TWL4030_MODULE_GPIO, message,
 448                                 REG_GPIOPUPDCTR1, 5);
 449 }
 450 
 451 static int gpio_twl4030_debounce(u32 debounce, u8 mmc_cd)
 452 {
 453         u8              message[3];
 454 
 455         /* 30 msec of debouncing is always used for MMC card detect,
 456          * and is optional for everything else.
 457          */
 458         message[0] = (debounce & 0xff) | (mmc_cd & 0x03);
 459         debounce >>= 8;
 460         message[1] = (debounce & 0xff);
 461         debounce >>= 8;
 462         message[2] = (debounce & 0x03);
 463 
 464         return twl_i2c_write(TWL4030_MODULE_GPIO, message,
 465                                 REG_GPIO_DEBEN1, 3);
 466 }
 467 
 468 static int gpio_twl4030_remove(struct platform_device *pdev);
 469 
 470 static struct twl4030_gpio_platform_data *of_gpio_twl4030(struct device *dev,
 471                                 struct twl4030_gpio_platform_data *pdata)
 472 {
 473         struct twl4030_gpio_platform_data *omap_twl_info;
 474 
 475         omap_twl_info = devm_kzalloc(dev, sizeof(*omap_twl_info), GFP_KERNEL);
 476         if (!omap_twl_info)
 477                 return NULL;
 478 
 479         if (pdata)
 480                 *omap_twl_info = *pdata;
 481 
 482         omap_twl_info->use_leds = of_property_read_bool(dev->of_node,
 483                         "ti,use-leds");
 484 
 485         of_property_read_u32(dev->of_node, "ti,debounce",
 486                              &omap_twl_info->debounce);
 487         of_property_read_u32(dev->of_node, "ti,mmc-cd",
 488                              (u32 *)&omap_twl_info->mmc_cd);
 489         of_property_read_u32(dev->of_node, "ti,pullups",
 490                              &omap_twl_info->pullups);
 491         of_property_read_u32(dev->of_node, "ti,pulldowns",
 492                              &omap_twl_info->pulldowns);
 493 
 494         return omap_twl_info;
 495 }
 496 
 497 static int gpio_twl4030_probe(struct platform_device *pdev)
 498 {
 499         struct twl4030_gpio_platform_data *pdata = dev_get_platdata(&pdev->dev);
 500         struct device_node *node = pdev->dev.of_node;
 501         struct gpio_twl4030_priv *priv;
 502         int ret, irq_base;
 503 
 504         priv = devm_kzalloc(&pdev->dev, sizeof(struct gpio_twl4030_priv),
 505                             GFP_KERNEL);
 506         if (!priv)
 507                 return -ENOMEM;
 508 
 509         /* maybe setup IRQs */
 510         if (is_module()) {
 511                 dev_err(&pdev->dev, "can't dispatch IRQs from modules\n");
 512                 goto no_irqs;
 513         }
 514 
 515         irq_base = devm_irq_alloc_descs(&pdev->dev, -1,
 516                                         0, TWL4030_GPIO_MAX, 0);
 517         if (irq_base < 0) {
 518                 dev_err(&pdev->dev, "Failed to alloc irq_descs\n");
 519                 return irq_base;
 520         }
 521 
 522         irq_domain_add_legacy(node, TWL4030_GPIO_MAX, irq_base, 0,
 523                               &irq_domain_simple_ops, NULL);
 524 
 525         ret = twl4030_sih_setup(&pdev->dev, TWL4030_MODULE_GPIO, irq_base);
 526         if (ret < 0)
 527                 return ret;
 528 
 529         priv->irq_base = irq_base;
 530 
 531 no_irqs:
 532         priv->gpio_chip = template_chip;
 533         priv->gpio_chip.base = -1;
 534         priv->gpio_chip.ngpio = TWL4030_GPIO_MAX;
 535         priv->gpio_chip.parent = &pdev->dev;
 536 
 537         mutex_init(&priv->mutex);
 538 
 539         if (node)
 540                 pdata = of_gpio_twl4030(&pdev->dev, pdata);
 541 
 542         if (pdata == NULL) {
 543                 dev_err(&pdev->dev, "Platform data is missing\n");
 544                 return -ENXIO;
 545         }
 546 
 547         /*
 548          * NOTE:  boards may waste power if they don't set pullups
 549          * and pulldowns correctly ... default for non-ULPI pins is
 550          * pulldown, and some other pins may have external pullups
 551          * or pulldowns.  Careful!
 552          */
 553         ret = gpio_twl4030_pulls(pdata->pullups, pdata->pulldowns);
 554         if (ret)
 555                 dev_dbg(&pdev->dev, "pullups %.05x %.05x --> %d\n",
 556                         pdata->pullups, pdata->pulldowns, ret);
 557 
 558         ret = gpio_twl4030_debounce(pdata->debounce, pdata->mmc_cd);
 559         if (ret)
 560                 dev_dbg(&pdev->dev, "debounce %.03x %.01x --> %d\n",
 561                         pdata->debounce, pdata->mmc_cd, ret);
 562 
 563         /*
 564          * NOTE: we assume VIBRA_CTL.VIBRA_EN, in MODULE_AUDIO_VOICE,
 565          * is (still) clear if use_leds is set.
 566          */
 567         if (pdata->use_leds)
 568                 priv->gpio_chip.ngpio += 2;
 569 
 570         ret = gpiochip_add_data(&priv->gpio_chip, priv);
 571         if (ret < 0) {
 572                 dev_err(&pdev->dev, "could not register gpiochip, %d\n", ret);
 573                 priv->gpio_chip.ngpio = 0;
 574                 gpio_twl4030_remove(pdev);
 575                 goto out;
 576         }
 577 
 578         platform_set_drvdata(pdev, priv);
 579 
 580         if (pdata->setup) {
 581                 int status;
 582 
 583                 status = pdata->setup(&pdev->dev, priv->gpio_chip.base,
 584                                       TWL4030_GPIO_MAX);
 585                 if (status)
 586                         dev_dbg(&pdev->dev, "setup --> %d\n", status);
 587         }
 588 
 589 out:
 590         return ret;
 591 }
 592 
 593 /* Cannot use as gpio_twl4030_probe() calls us */
 594 static int gpio_twl4030_remove(struct platform_device *pdev)
 595 {
 596         struct twl4030_gpio_platform_data *pdata = dev_get_platdata(&pdev->dev);
 597         struct gpio_twl4030_priv *priv = platform_get_drvdata(pdev);
 598         int status;
 599 
 600         if (pdata && pdata->teardown) {
 601                 status = pdata->teardown(&pdev->dev, priv->gpio_chip.base,
 602                                          TWL4030_GPIO_MAX);
 603                 if (status) {
 604                         dev_dbg(&pdev->dev, "teardown --> %d\n", status);
 605                         return status;
 606                 }
 607         }
 608 
 609         gpiochip_remove(&priv->gpio_chip);
 610 
 611         if (is_module())
 612                 return 0;
 613 
 614         /* REVISIT no support yet for deregistering all the IRQs */
 615         WARN_ON(1);
 616         return -EIO;
 617 }
 618 
 619 static const struct of_device_id twl_gpio_match[] = {
 620         { .compatible = "ti,twl4030-gpio", },
 621         { },
 622 };
 623 MODULE_DEVICE_TABLE(of, twl_gpio_match);
 624 
 625 /* Note:  this hardware lives inside an I2C-based multi-function device. */
 626 MODULE_ALIAS("platform:twl4030_gpio");
 627 
 628 static struct platform_driver gpio_twl4030_driver = {
 629         .driver = {
 630                 .name   = "twl4030_gpio",
 631                 .of_match_table = twl_gpio_match,
 632         },
 633         .probe          = gpio_twl4030_probe,
 634         .remove         = gpio_twl4030_remove,
 635 };
 636 
 637 static int __init gpio_twl4030_init(void)
 638 {
 639         return platform_driver_register(&gpio_twl4030_driver);
 640 }
 641 subsys_initcall(gpio_twl4030_init);
 642 
 643 static void __exit gpio_twl4030_exit(void)
 644 {
 645         platform_driver_unregister(&gpio_twl4030_driver);
 646 }
 647 module_exit(gpio_twl4030_exit);
 648 
 649 MODULE_AUTHOR("Texas Instruments, Inc.");
 650 MODULE_DESCRIPTION("GPIO interface for TWL4030");
 651 MODULE_LICENSE("GPL");