drivers/video/backlight/pwm_bl.c

   1 /*
   2  * linux/drivers/video/backlight/pwm_bl.c
   3  *
   4  * simple PWM based backlight control, board code has to setup
   5  * 1) pin configuration so PWM waveforms can output
   6  * 2) platform_data being correctly configured
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/delay.h>
  14 #include <linux/gpio/consumer.h>
  15 #include <linux/gpio.h>
  16 #include <linux/module.h>
  17 #include <linux/kernel.h>
  18 #include <linux/init.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/fb.h>
  21 #include <linux/backlight.h>
  22 #include <linux/err.h>
  23 #include <linux/pwm.h>
  24 #include <linux/pwm_backlight.h>
  25 #include <linux/regulator/consumer.h>
  26 #include <linux/slab.h>
  27
  28 struct pwm_bl_data {
  29         struct pwm_device       *pwm;
  30         struct device           *dev;
  31         unsigned int            lth_brightness;
  32         unsigned int            *levels;
  33         struct regulator        *power_supply;
  34         struct gpio_desc        *enable_gpio;
  35         unsigned int            scale;
  36         bool                    legacy;
  37         unsigned int            post_pwm_on_delay;
  38         unsigned int            pwm_off_delay;
  39         int                     (*notify)(struct device *,
  40                                           int brightness);
  41         void                    (*notify_after)(struct device *,
  42                                         int brightness);
  43         int                     (*check_fb)(struct device *, struct fb_info *);
  44         void                    (*exit)(struct device *);
  45 };
  46
  47 static void pwm_backlight_power_on(struct pwm_bl_data *pb)
  48 {
  49         struct pwm_state state;
  50         int err;
  51
  52         pwm_get_state(pb->pwm, &state);
  53         if (state.enabled)
  54                 return;
  55
  56         err = regulator_enable(pb->power_supply);
  57         if (err < 0)
  58                 dev_err(pb->dev, "failed to enable power supply\n");
  59
  60         state.enabled = true;
  61         pwm_apply_state(pb->pwm, &state);
  62
  63         if (pb->post_pwm_on_delay)
  64                 msleep(pb->post_pwm_on_delay);
  65
  66         if (pb->enable_gpio)
  67                 gpiod_set_value_cansleep(pb->enable_gpio, 1);
  68 }
  69
  70 static void pwm_backlight_power_off(struct pwm_bl_data *pb)
  71 {
  72         struct pwm_state state;
  73
  74         pwm_get_state(pb->pwm, &state);
  75         if (!state.enabled)
  76                 return;
  77
  78         if (pb->enable_gpio)
  79                 gpiod_set_value_cansleep(pb->enable_gpio, 0);
  80
  81         if (pb->pwm_off_delay)
  82                 msleep(pb->pwm_off_delay);
  83
  84         state.enabled = false;
  85         state.duty_cycle = 0;
  86         pwm_apply_state(pb->pwm, &state);
  87
  88         regulator_disable(pb->power_supply);
  89 }
  90
  91 static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)
  92 {
  93         unsigned int lth = pb->lth_brightness;
  94         struct pwm_state state;
  95         u64 duty_cycle;
  96
  97         pwm_get_state(pb->pwm, &state);
  98
  99         if (pb->levels)
 100                 duty_cycle = pb->levels[brightness];
 101         else
 102                 duty_cycle = brightness;
 103
 104         duty_cycle *= state.period - lth;
 105         do_div(duty_cycle, pb->scale);
 106
 107         return duty_cycle + lth;
 108 }
 109
 110 static int pwm_backlight_update_status(struct backlight_device *bl)
 111 {
 112         struct pwm_bl_data *pb = bl_get_data(bl);
 113         int brightness = bl->props.brightness;
 114         struct pwm_state state;
 115
 116         if (bl->props.power != FB_BLANK_UNBLANK ||
 117             bl->props.fb_blank != FB_BLANK_UNBLANK ||
 118             bl->props.state & BL_CORE_FBBLANK)
 119                 brightness = 0;
 120
 121         if (pb->notify)
 122                 brightness = pb->notify(pb->dev, brightness);
 123
 124         if (brightness > 0) {
 125                 pwm_get_state(pb->pwm, &state);
 126                 state.duty_cycle = compute_duty_cycle(pb, brightness);
 127                 pwm_apply_state(pb->pwm, &state);
 128                 pwm_backlight_power_on(pb);
 129         } else
 130                 pwm_backlight_power_off(pb);
 131
 132         if (pb->notify_after)
 133                 pb->notify_after(pb->dev, brightness);
 134
 135         return 0;
 136 }
 137
 138 static int pwm_backlight_check_fb(struct backlight_device *bl,
 139                                   struct fb_info *info)
 140 {
 141         struct pwm_bl_data *pb = bl_get_data(bl);
 142
 143         return !pb->check_fb || pb->check_fb(pb->dev, info);
 144 }
 145
 146 static const struct backlight_ops pwm_backlight_ops = {
 147         .update_status  = pwm_backlight_update_status,
 148         .check_fb       = pwm_backlight_check_fb,
 149 };
 150
 151 #ifdef CONFIG_OF
 152 #define PWM_LUMINANCE_SCALE     10000 /* luminance scale */
 153
 154 /* An integer based power function */
 155 static u64 int_pow(u64 base, int exp)
 156 {
 157         u64 result = 1;
 158
 159         while (exp) {
 160                 if (exp & 1)
 161                         result *= base;
 162                 exp >>= 1;
 163                 base *= base;
 164         }
 165
 166         return result;
 167 }
 168
 169 /*
 170  * CIE lightness to PWM conversion.
 171  *
 172  * The CIE 1931 lightness formula is what actually describes how we perceive
 173  * light:
 174  *          Y = (L* / 902.3)           if L* ≤ 0.08856
 175  *          Y = ((L* + 16) / 116)^3    if L* > 0.08856
 176  *
 177  * Where Y is the luminance, the amount of light coming out of the screen, and
 178  * is a number between 0.0 and 1.0; and L* is the lightness, how bright a human
 179  * perceives the screen to be, and is a number between 0 and 100.
 180  *
 181  * The following function does the fixed point maths needed to implement the
 182  * above formula.
 183  */
 184 static u64 cie1931(unsigned int lightness, unsigned int scale)
 185 {
 186         u64 retval;
 187
 188         lightness *= 100;
 189         if (lightness <= (8 * scale)) {
 190                 retval = DIV_ROUND_CLOSEST_ULL(lightness * 10, 9023);
 191         } else {
 192                 retval = int_pow((lightness + (16 * scale)) / 116, 3);
 193                 retval = DIV_ROUND_CLOSEST_ULL(retval, (scale * scale));
 194         }
 195
 196         return retval;
 197 }
 198
 199 /*
 200  * Create a default correction table for PWM values to create linear brightness
 201  * for LED based backlights using the CIE1931 algorithm.
 202  */
 203 static
 204 int pwm_backlight_brightness_default(struct device *dev,
 205                                      struct platform_pwm_backlight_data *data,
 206                                      unsigned int period)
 207 {
 208         unsigned int counter = 0;
 209         unsigned int i, n;
 210         u64 retval;
 211
 212         /*
 213          * Count the number of bits needed to represent the period number. The
 214          * number of bits is used to calculate the number of levels used for the
 215          * brightness-levels table, the purpose of this calculation is have a
 216          * pre-computed table with enough levels to get linear brightness
 217          * perception. The period is divided by the number of bits so for a
 218          * 8-bit PWM we have 255 / 8 = 32 brightness levels or for a 16-bit PWM
 219          * we have 65535 / 16 = 4096 brightness levels.
 220          *
 221          * Note that this method is based on empirical testing on different
 222          * devices with PWM of 8 and 16 bits of resolution.
 223          */
 224         n = period;
 225         while (n) {
 226                 counter += n % 2;
 227                 n >>= 1;
 228         }
 229
 230         data->max_brightness = DIV_ROUND_UP(period, counter);
 231         data->levels = devm_kcalloc(dev, data->max_brightness,
 232                                     sizeof(*data->levels), GFP_KERNEL);
 233         if (!data->levels)
 234                 return -ENOMEM;
 235
 236         /* Fill the table using the cie1931 algorithm */
 237         for (i = 0; i < data->max_brightness; i++) {
 238                 retval = cie1931((i * PWM_LUMINANCE_SCALE) /
 239                                  data->max_brightness, PWM_LUMINANCE_SCALE) *
 240                                  period;
 241                 retval = DIV_ROUND_CLOSEST_ULL(retval, PWM_LUMINANCE_SCALE);
 242                 if (retval > UINT_MAX)
 243                         return -EINVAL;
 244                 data->levels[i] = (unsigned int)retval;
 245         }
 246
 247         data->dft_brightness = data->max_brightness / 2;
 248         data->max_brightness--;
 249
 250         return 0;
 251 }
 252
 253 static int pwm_backlight_parse_dt(struct device *dev,
 254                                   struct platform_pwm_backlight_data *data)
 255 {
 256         struct device_node *node = dev->of_node;
 257         unsigned int num_levels = 0;
 258         unsigned int levels_count;
 259         unsigned int num_steps = 0;
 260         struct property *prop;
 261         unsigned int *table;
 262         int length;
 263         u32 value;
 264         int ret;
 265
 266         if (!node)
 267                 return -ENODEV;
 268
 269         memset(data, 0, sizeof(*data));
 270
 271         /*
 272          * Determine the number of brightness levels, if this property is not
 273          * set a default table of brightness levels will be used.
 274          */
 275         prop = of_find_property(node, "brightness-levels", &length);
 276         if (!prop)
 277                 return 0;
 278
 279         data->max_brightness = length / sizeof(u32);
 280
 281         /* read brightness levels from DT property */
 282         if (data->max_brightness > 0) {
 283                 size_t size = sizeof(*data->levels) * data->max_brightness;
 284                 unsigned int i, j, n = 0;
 285
 286                 data->levels = devm_kzalloc(dev, size, GFP_KERNEL);
 287                 if (!data->levels)
 288                         return -ENOMEM;
 289
 290                 ret = of_property_read_u32_array(node, "brightness-levels",
 291                                                  data->levels,
 292                                                  data->max_brightness);
 293                 if (ret < 0)
 294                         return ret;
 295
 296                 ret = of_property_read_u32(node, "default-brightness-level",
 297                                            &value);
 298                 if (ret < 0)
 299                         return ret;
 300
 301                 data->dft_brightness = value;
 302
 303                 /*
 304                  * This property is optional, if is set enables linear
 305                  * interpolation between each of the values of brightness levels
 306                  * and creates a new pre-computed table.
 307                  */
 308                 of_property_read_u32(node, "num-interpolated-steps",
 309                                      &num_steps);
 310
 311                 /*
 312                  * Make sure that there is at least two entries in the
 313                  * brightness-levels table, otherwise we can't interpolate
 314                  * between two points.
 315                  */
 316                 if (num_steps) {
 317                         if (data->max_brightness < 2) {
 318                                 dev_err(dev, "can't interpolate\n");
 319                                 return -EINVAL;
 320                         }
 321
 322                         /*
 323                          * Recalculate the number of brightness levels, now
 324                          * taking in consideration the number of interpolated
 325                          * steps between two levels.
 326                          */
 327                         for (i = 0; i < data->max_brightness - 1; i++) {
 328                                 if ((data->levels[i + 1] - data->levels[i]) /
 329                                    num_steps)
 330                                         num_levels += num_steps;
 331                                 else
 332                                         num_levels++;
 333                         }
 334                         num_levels++;
 335                         dev_dbg(dev, "new number of brightness levels: %d\n",
 336                                 num_levels);
 337
 338                         /*
 339                          * Create a new table of brightness levels with all the
 340                          * interpolated steps.
 341                          */
 342                         size = sizeof(*table) * num_levels;
 343                         table = devm_kzalloc(dev, size, GFP_KERNEL);
 344                         if (!table)
 345                                 return -ENOMEM;
 346
 347                         /* Fill the interpolated table. */
 348                         levels_count = 0;
 349                         for (i = 0; i < data->max_brightness - 1; i++) {
 350                                 value = data->levels[i];
 351                                 n = (data->levels[i + 1] - value) / num_steps;
 352                                 if (n > 0) {
 353                                         for (j = 0; j < num_steps; j++) {
 354                                                 table[levels_count] = value;
 355                                                 value += n;
 356                                                 levels_count++;
 357                                         }
 358                                 } else {
 359                                         table[levels_count] = data->levels[i];
 360                                         levels_count++;
 361                                 }
 362                         }
 363                         table[levels_count] = data->levels[i];
 364
 365                         /*
 366                          * As we use interpolation lets remove current
 367                          * brightness levels table and replace for the
 368                          * new interpolated table.
 369                          */
 370                         devm_kfree(dev, data->levels);
 371                         data->levels = table;
 372
 373                         /*
 374                          * Reassign max_brightness value to the new total number
 375                          * of brightness levels.
 376                          */
 377                         data->max_brightness = num_levels;
 378                 }
 379
 380                 data->max_brightness--;
 381         }
 382
 383         /*
 384          * These values are optional and set as 0 by default, the out values
 385          * are modified only if a valid u32 value can be decoded.
 386          */
 387         of_property_read_u32(node, "post-pwm-on-delay-ms",
 388                              &data->post_pwm_on_delay);
 389         of_property_read_u32(node, "pwm-off-delay-ms", &data->pwm_off_delay);
 390
 391         data->enable_gpio = -EINVAL;
 392         return 0;
 393 }
 394
 395 static const struct of_device_id pwm_backlight_of_match[] = {
 396         { .compatible = "pwm-backlight" },
 397         { }
 398 };
 399
 400 MODULE_DEVICE_TABLE(of, pwm_backlight_of_match);
 401 #else
 402 static int pwm_backlight_parse_dt(struct device *dev,
 403                                   struct platform_pwm_backlight_data *data)
 404 {
 405         return -ENODEV;
 406 }
 407
 408 static
 409 int pwm_backlight_brightness_default(struct device *dev,
 410                                      struct platform_pwm_backlight_data *data,
 411                                      unsigned int period)
 412 {
 413         return -ENODEV;
 414 }
 415 #endif
 416
 417 static int pwm_backlight_initial_power_state(const struct pwm_bl_data *pb)
 418 {
 419         struct device_node *node = pb->dev->of_node;
 420
 421         /* Not booted with device tree or no phandle link to the node */
 422         if (!node || !node->phandle)
 423                 return FB_BLANK_UNBLANK;
 424
 425         /*
 426          * If the driver is probed from the device tree and there is a
 427          * phandle link pointing to the backlight node, it is safe to
 428          * assume that another driver will enable the backlight at the
 429          * appropriate time. Therefore, if it is disabled, keep it so.
 430          */
 431
 432         /* if the enable GPIO is disabled, do not enable the backlight */
 433         if (pb->enable_gpio && gpiod_get_value(pb->enable_gpio) == 0)
 434                 return FB_BLANK_POWERDOWN;
 435
 436         /* The regulator is disabled, do not enable the backlight */
 437         if (!regulator_is_enabled(pb->power_supply))
 438                 return FB_BLANK_POWERDOWN;
 439
 440         /* The PWM is disabled, keep it like this */
 441         if (!pwm_is_enabled(pb->pwm))
 442                 return FB_BLANK_POWERDOWN;
 443
 444         return FB_BLANK_UNBLANK;
 445 }
 446
 447 static int pwm_backlight_probe(struct platform_device *pdev)
 448 {
 449         struct platform_pwm_backlight_data *data = dev_get_platdata(&pdev->dev);
 450         struct platform_pwm_backlight_data defdata;
 451         struct backlight_properties props;
 452         struct backlight_device *bl;
 453         struct device_node *node = pdev->dev.of_node;
 454         struct pwm_bl_data *pb;
 455         struct pwm_state state;
 456         unsigned int i;
 457         int ret;
 458
 459         if (!data) {
 460                 ret = pwm_backlight_parse_dt(&pdev->dev, &defdata);
 461                 if (ret < 0) {
 462                         dev_err(&pdev->dev, "failed to find platform data\n");
 463                         return ret;
 464                 }
 465
 466                 data = &defdata;
 467         }
 468
 469         if (data->init) {
 470                 ret = data->init(&pdev->dev);
 471                 if (ret < 0)
 472                         return ret;
 473         }
 474
 475         pb = devm_kzalloc(&pdev->dev, sizeof(*pb), GFP_KERNEL);
 476         if (!pb) {
 477                 ret = -ENOMEM;
 478                 goto err_alloc;
 479         }
 480
 481         pb->notify = data->notify;
 482         pb->notify_after = data->notify_after;
 483         pb->check_fb = data->check_fb;
 484         pb->exit = data->exit;
 485         pb->dev = &pdev->dev;
 486         pb->post_pwm_on_delay = data->post_pwm_on_delay;
 487         pb->pwm_off_delay = data->pwm_off_delay;
 488
 489         pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
 490                                                   GPIOD_ASIS);
 491         if (IS_ERR(pb->enable_gpio)) {
 492                 ret = PTR_ERR(pb->enable_gpio);
 493                 goto err_alloc;
 494         }
 495
 496         /*
 497          * Compatibility fallback for drivers still using the integer GPIO
 498          * platform data. Must go away soon.
 499          */
 500         if (!pb->enable_gpio && gpio_is_valid(data->enable_gpio)) {
 501                 ret = devm_gpio_request_one(&pdev->dev, data->enable_gpio,
 502                                             GPIOF_OUT_INIT_HIGH, "enable");
 503                 if (ret < 0) {
 504                         dev_err(&pdev->dev, "failed to request GPIO#%d: %d\n",
 505                                 data->enable_gpio, ret);
 506                         goto err_alloc;
 507                 }
 508
 509                 pb->enable_gpio = gpio_to_desc(data->enable_gpio);
 510         }
 511
 512         /*
 513          * If the GPIO is not known to be already configured as output, that
 514          * is, if gpiod_get_direction returns either 1 or -EINVAL, change the
 515          * direction to output and set the GPIO as active.
 516          * Do not force the GPIO to active when it was already output as it
 517          * could cause backlight flickering or we would enable the backlight too
 518          * early. Leave the decision of the initial backlight state for later.
 519          */
 520         if (pb->enable_gpio &&
 521             gpiod_get_direction(pb->enable_gpio) != 0)
 522                 gpiod_direction_output(pb->enable_gpio, 1);
 523
 524         pb->power_supply = devm_regulator_get(&pdev->dev, "power");
 525         if (IS_ERR(pb->power_supply)) {
 526                 ret = PTR_ERR(pb->power_supply);
 527                 goto err_alloc;
 528         }
 529
 530         pb->pwm = devm_pwm_get(&pdev->dev, NULL);
 531         if (IS_ERR(pb->pwm) && PTR_ERR(pb->pwm) != -EPROBE_DEFER && !node) {
 532                 dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
 533                 pb->legacy = true;
 534                 pb->pwm = pwm_request(data->pwm_id, "pwm-backlight");
 535         }
 536
 537         if (IS_ERR(pb->pwm)) {
 538                 ret = PTR_ERR(pb->pwm);
 539                 if (ret != -EPROBE_DEFER)
 540                         dev_err(&pdev->dev, "unable to request PWM\n");
 541                 goto err_alloc;
 542         }
 543
 544         dev_dbg(&pdev->dev, "got pwm for backlight\n");
 545
 546         /* Sync up PWM state. */
 547         pwm_init_state(pb->pwm, &state);
 548
 549         /*
 550          * The DT case will set the pwm_period_ns field to 0 and store the
 551          * period, parsed from the DT, in the PWM device. For the non-DT case,
 552          * set the period from platform data if it has not already been set
 553          * via the PWM lookup table.
 554          */
 555         if (!state.period && (data->pwm_period_ns > 0))
 556                 state.period = data->pwm_period_ns;
 557
 558         ret = pwm_apply_state(pb->pwm, &state);
 559         if (ret) {
 560                 dev_err(&pdev->dev, "failed to apply initial PWM state: %d\n",
 561                         ret);
 562                 goto err_alloc;
 563         }
 564
 565         if (data->levels) {
 566                 /*
 567                  * For the DT case, only when brightness levels is defined
 568                  * data->levels is filled. For the non-DT case, data->levels
 569                  * can come from platform data, however is not usual.
 570                  */
 571                 for (i = 0; i <= data->max_brightness; i++) {
 572                         if (data->levels[i] > pb->scale)
 573                                 pb->scale = data->levels[i];
 574
 575                         pb->levels = data->levels;
 576                 }
 577         } else if (!data->max_brightness) {
 578                 /*
 579                  * If no brightness levels are provided and max_brightness is
 580                  * not set, use the default brightness table. For the DT case,
 581                  * max_brightness is set to 0 when brightness levels is not
 582                  * specified. For the non-DT case, max_brightness is usually
 583                  * set to some value.
 584                  */
 585
 586                 /* Get the PWM period (in nanoseconds) */
 587                 pwm_get_state(pb->pwm, &state);
 588
 589                 ret = pwm_backlight_brightness_default(&pdev->dev, data,
 590                                                        state.period);
 591                 if (ret < 0) {
 592                         dev_err(&pdev->dev,
 593                                 "failed to setup default brightness table\n");
 594                         goto err_alloc;
 595                 }
 596
 597                 for (i = 0; i <= data->max_brightness; i++) {
 598                         if (data->levels[i] > pb->scale)
 599                                 pb->scale = data->levels[i];
 600
 601                         pb->levels = data->levels;
 602                 }
 603         } else {
 604                 /*
 605                  * That only happens for the non-DT case, where platform data
 606                  * sets the max_brightness value.
 607                  */
 608                 pb->scale = data->max_brightness;
 609         }
 610
 611         pb->lth_brightness = data->lth_brightness * (state.period / pb->scale);
 612
 613         memset(&props, 0, sizeof(struct backlight_properties));
 614         props.type = BACKLIGHT_RAW;
 615         props.max_brightness = data->max_brightness;
 616         bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
 617                                        &pwm_backlight_ops, &props);
 618         if (IS_ERR(bl)) {
 619                 dev_err(&pdev->dev, "failed to register backlight\n");
 620                 ret = PTR_ERR(bl);
 621                 if (pb->legacy)
 622                         pwm_free(pb->pwm);
 623                 goto err_alloc;
 624         }
 625
 626         if (data->dft_brightness > data->max_brightness) {
 627                 dev_warn(&pdev->dev,
 628                          "invalid default brightness level: %u, using %u\n",
 629                          data->dft_brightness, data->max_brightness);
 630                 data->dft_brightness = data->max_brightness;
 631         }
 632
 633         bl->props.brightness = data->dft_brightness;
 634         bl->props.power = pwm_backlight_initial_power_state(pb);
 635         backlight_update_status(bl);
 636
 637         platform_set_drvdata(pdev, bl);
 638         return 0;
 639
 640 err_alloc:
 641         if (data->exit)
 642                 data->exit(&pdev->dev);
 643         return ret;
 644 }
 645
 646 static int pwm_backlight_remove(struct platform_device *pdev)
 647 {
 648         struct backlight_device *bl = platform_get_drvdata(pdev);
 649         struct pwm_bl_data *pb = bl_get_data(bl);
 650
 651         backlight_device_unregister(bl);
 652         pwm_backlight_power_off(pb);
 653
 654         if (pb->exit)
 655                 pb->exit(&pdev->dev);
 656         if (pb->legacy)
 657                 pwm_free(pb->pwm);
 658
 659         return 0;
 660 }
 661
 662 static void pwm_backlight_shutdown(struct platform_device *pdev)
 663 {
 664         struct backlight_device *bl = platform_get_drvdata(pdev);
 665         struct pwm_bl_data *pb = bl_get_data(bl);
 666
 667         pwm_backlight_power_off(pb);
 668 }
 669
 670 #ifdef CONFIG_PM_SLEEP
 671 static int pwm_backlight_suspend(struct device *dev)
 672 {
 673         struct backlight_device *bl = dev_get_drvdata(dev);
 674         struct pwm_bl_data *pb = bl_get_data(bl);
 675
 676         if (pb->notify)
 677                 pb->notify(pb->dev, 0);
 678
 679         pwm_backlight_power_off(pb);
 680
 681         if (pb->notify_after)
 682                 pb->notify_after(pb->dev, 0);
 683
 684         return 0;
 685 }
 686
 687 static int pwm_backlight_resume(struct device *dev)
 688 {
 689         struct backlight_device *bl = dev_get_drvdata(dev);
 690
 691         backlight_update_status(bl);
 692
 693         return 0;
 694 }
 695 #endif
 696
 697 static const struct dev_pm_ops pwm_backlight_pm_ops = {
 698 #ifdef CONFIG_PM_SLEEP
 699         .suspend = pwm_backlight_suspend,
 700         .resume = pwm_backlight_resume,
 701         .poweroff = pwm_backlight_suspend,
 702         .restore = pwm_backlight_resume,
 703 #endif
 704 };
 705
 706 static struct platform_driver pwm_backlight_driver = {
 707         .driver         = {
 708                 .name           = "pwm-backlight",
 709                 .pm             = &pwm_backlight_pm_ops,
 710                 .of_match_table = of_match_ptr(pwm_backlight_of_match),
 711         },
 712         .probe          = pwm_backlight_probe,
 713         .remove         = pwm_backlight_remove,
 714         .shutdown       = pwm_backlight_shutdown,
 715 };
 716
 717 module_platform_driver(pwm_backlight_driver);
 718
 719 MODULE_DESCRIPTION("PWM based Backlight Driver");
 720 MODULE_LICENSE("GPL");
 721 MODULE_ALIAS("platform:pwm-backlight");