drivers/video/backlight/pwm_bl.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Simple PWM based backlight control, board code has to setup
   4  * 1) pin configuration so PWM waveforms can output
   5  * 2) platform_data being correctly configured
   6  */
   7
   8 #include <linux/delay.h>
   9 #include <linux/gpio/consumer.h>
  10 #include <linux/gpio.h>
  11 #include <linux/module.h>
  12 #include <linux/kernel.h>
  13 #include <linux/init.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/fb.h>
  16 #include <linux/backlight.h>
  17 #include <linux/err.h>
  18 #include <linux/pwm.h>
  19 #include <linux/pwm_backlight.h>
  20 #include <linux/regulator/consumer.h>
  21 #include <linux/slab.h>
  22
  23 struct pwm_bl_data {
  24         struct pwm_device       *pwm;
  25         struct device           *dev;
  26         unsigned int            lth_brightness;
  27         unsigned int            *levels;
  28         bool                    enabled;
  29         struct regulator        *power_supply;
  30         struct gpio_desc        *enable_gpio;
  31         unsigned int            scale;
  32         bool                    legacy;
  33         unsigned int            post_pwm_on_delay;
  34         unsigned int            pwm_off_delay;
  35         int                     (*notify)(struct device *,
  36                                           int brightness);
  37         void                    (*notify_after)(struct device *,
  38                                         int brightness);
  39         int                     (*check_fb)(struct device *, struct fb_info *);
  40         void                    (*exit)(struct device *);
  41 };
  42
  43 static void pwm_backlight_power_on(struct pwm_bl_data *pb)
  44 {
  45         struct pwm_state state;
  46         int err;
  47
  48         pwm_get_state(pb->pwm, &state);
  49         if (pb->enabled)
  50                 return;
  51
  52         err = regulator_enable(pb->power_supply);
  53         if (err < 0)
  54                 dev_err(pb->dev, "failed to enable power supply\n");
  55
  56         state.enabled = true;
  57         pwm_apply_state(pb->pwm, &state);
  58
  59         if (pb->post_pwm_on_delay)
  60                 msleep(pb->post_pwm_on_delay);
  61
  62         if (pb->enable_gpio)
  63                 gpiod_set_value_cansleep(pb->enable_gpio, 1);
  64
  65         pb->enabled = true;
  66 }
  67
  68 static void pwm_backlight_power_off(struct pwm_bl_data *pb)
  69 {
  70         struct pwm_state state;
  71
  72         pwm_get_state(pb->pwm, &state);
  73         if (!pb->enabled)
  74                 return;
  75
  76         if (pb->enable_gpio)
  77                 gpiod_set_value_cansleep(pb->enable_gpio, 0);
  78
  79         if (pb->pwm_off_delay)
  80                 msleep(pb->pwm_off_delay);
  81
  82         state.enabled = false;
  83         state.duty_cycle = 0;
  84         pwm_apply_state(pb->pwm, &state);
  85
  86         regulator_disable(pb->power_supply);
  87         pb->enabled = false;
  88 }
  89
  90 static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)
  91 {
  92         unsigned int lth = pb->lth_brightness;
  93         struct pwm_state state;
  94         u64 duty_cycle;
  95
  96         pwm_get_state(pb->pwm, &state);
  97
  98         if (pb->levels)
  99                 duty_cycle = pb->levels[brightness];
 100         else
 101                 duty_cycle = brightness;
 102
 103         duty_cycle *= state.period - lth;
 104         do_div(duty_cycle, pb->scale);
 105
 106         return duty_cycle + lth;
 107 }
 108
 109 static int pwm_backlight_update_status(struct backlight_device *bl)
 110 {
 111         struct pwm_bl_data *pb = bl_get_data(bl);
 112         int brightness = bl->props.brightness;
 113         struct pwm_state state;
 114
 115         if (bl->props.power != FB_BLANK_UNBLANK ||
 116             bl->props.fb_blank != FB_BLANK_UNBLANK ||
 117             bl->props.state & BL_CORE_FBBLANK)
 118                 brightness = 0;
 119
 120         if (pb->notify)
 121                 brightness = pb->notify(pb->dev, brightness);
 122
 123         if (brightness > 0) {
 124                 pwm_get_state(pb->pwm, &state);
 125                 state.duty_cycle = compute_duty_cycle(pb, brightness);
 126                 pwm_apply_state(pb->pwm, &state);
 127                 pwm_backlight_power_on(pb);
 128         } else {
 129                 pwm_backlight_power_off(pb);
 130         }
 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 /*
 155  * CIE lightness to PWM conversion.
 156  *
 157  * The CIE 1931 lightness formula is what actually describes how we perceive
 158  * light:
 159  *          Y = (L* / 903.3)           if L* ≤ 8
 160  *          Y = ((L* + 16) / 116)^3    if L* > 8
 161  *
 162  * Where Y is the luminance, the amount of light coming out of the screen, and
 163  * is a number between 0.0 and 1.0; and L* is the lightness, how bright a human
 164  * perceives the screen to be, and is a number between 0 and 100.
 165  *
 166  * The following function does the fixed point maths needed to implement the
 167  * above formula.
 168  */
 169 static u64 cie1931(unsigned int lightness, unsigned int scale)
 170 {
 171         u64 retval;
 172
 173         /*
 174          * @lightness is given as a number between 0 and 1, expressed
 175          * as a fixed-point number in scale @scale. Convert to a
 176          * percentage, still expressed as a fixed-point number, so the
 177          * above formulas can be applied.
 178          */
 179         lightness *= 100;
 180         if (lightness <= (8 * scale)) {
 181                 retval = DIV_ROUND_CLOSEST_ULL(lightness * 10, 9033);
 182         } else {
 183                 retval = int_pow((lightness + (16 * scale)) / 116, 3);
 184                 retval = DIV_ROUND_CLOSEST_ULL(retval, (scale * scale));
 185         }
 186
 187         return retval;
 188 }
 189
 190 /*
 191  * Create a default correction table for PWM values to create linear brightness
 192  * for LED based backlights using the CIE1931 algorithm.
 193  */
 194 static
 195 int pwm_backlight_brightness_default(struct device *dev,
 196                                      struct platform_pwm_backlight_data *data,
 197                                      unsigned int period)
 198 {
 199         unsigned int i;
 200         u64 retval;
 201
 202         /*
 203          * Once we have 4096 levels there's little point going much higher...
 204          * neither interactive sliders nor animation benefits from having
 205          * more values in the table.
 206          */
 207         data->max_brightness =
 208                 min((int)DIV_ROUND_UP(period, fls(period)), 4096);
 209
 210         data->levels = devm_kcalloc(dev, data->max_brightness,
 211                                     sizeof(*data->levels), GFP_KERNEL);
 212         if (!data->levels)
 213                 return -ENOMEM;
 214
 215         /* Fill the table using the cie1931 algorithm */
 216         for (i = 0; i < data->max_brightness; i++) {
 217                 retval = cie1931((i * PWM_LUMINANCE_SCALE) /
 218                                  data->max_brightness, PWM_LUMINANCE_SCALE) *
 219                                  period;
 220                 retval = DIV_ROUND_CLOSEST_ULL(retval, PWM_LUMINANCE_SCALE);
 221                 if (retval > UINT_MAX)
 222                         return -EINVAL;
 223                 data->levels[i] = (unsigned int)retval;
 224         }
 225
 226         data->dft_brightness = data->max_brightness / 2;
 227         data->max_brightness--;
 228
 229         return 0;
 230 }
 231
 232 static int pwm_backlight_parse_dt(struct device *dev,
 233                                   struct platform_pwm_backlight_data *data)
 234 {
 235         struct device_node *node = dev->of_node;
 236         unsigned int num_levels = 0;
 237         unsigned int levels_count;
 238         unsigned int num_steps = 0;
 239         struct property *prop;
 240         unsigned int *table;
 241         int length;
 242         u32 value;
 243         int ret;
 244
 245         if (!node)
 246                 return -ENODEV;
 247
 248         memset(data, 0, sizeof(*data));
 249
 250         /*
 251          * These values are optional and set as 0 by default, the out values
 252          * are modified only if a valid u32 value can be decoded.
 253          */
 254         of_property_read_u32(node, "post-pwm-on-delay-ms",
 255                              &data->post_pwm_on_delay);
 256         of_property_read_u32(node, "pwm-off-delay-ms", &data->pwm_off_delay);
 257
 258         data->enable_gpio = -EINVAL;
 259
 260         /*
 261          * Determine the number of brightness levels, if this property is not
 262          * set a default table of brightness levels will be used.
 263          */
 264         prop = of_find_property(node, "brightness-levels", &length);
 265         if (!prop)
 266                 return 0;
 267
 268         data->max_brightness = length / sizeof(u32);
 269
 270         /* read brightness levels from DT property */
 271         if (data->max_brightness > 0) {
 272                 size_t size = sizeof(*data->levels) * data->max_brightness;
 273                 unsigned int i, j, n = 0;
 274
 275                 data->levels = devm_kzalloc(dev, size, GFP_KERNEL);
 276                 if (!data->levels)
 277                         return -ENOMEM;
 278
 279                 ret = of_property_read_u32_array(node, "brightness-levels",
 280                                                  data->levels,
 281                                                  data->max_brightness);
 282                 if (ret < 0)
 283                         return ret;
 284
 285                 ret = of_property_read_u32(node, "default-brightness-level",
 286                                            &value);
 287                 if (ret < 0)
 288                         return ret;
 289
 290                 data->dft_brightness = value;
 291
 292                 /*
 293                  * This property is optional, if is set enables linear
 294                  * interpolation between each of the values of brightness levels
 295                  * and creates a new pre-computed table.
 296                  */
 297                 of_property_read_u32(node, "num-interpolated-steps",
 298                                      &num_steps);
 299
 300                 /*
 301                  * Make sure that there is at least two entries in the
 302                  * brightness-levels table, otherwise we can't interpolate
 303                  * between two points.
 304                  */
 305                 if (num_steps) {
 306                         if (data->max_brightness < 2) {
 307                                 dev_err(dev, "can't interpolate\n");
 308                                 return -EINVAL;
 309                         }
 310
 311                         /*
 312                          * Recalculate the number of brightness levels, now
 313                          * taking in consideration the number of interpolated
 314                          * steps between two levels.
 315                          */
 316                         for (i = 0; i < data->max_brightness - 1; i++) {
 317                                 if ((data->levels[i + 1] - data->levels[i]) /
 318                                    num_steps)
 319                                         num_levels += num_steps;
 320                                 else
 321                                         num_levels++;
 322                         }
 323                         num_levels++;
 324                         dev_dbg(dev, "new number of brightness levels: %d\n",
 325                                 num_levels);
 326
 327                         /*
 328                          * Create a new table of brightness levels with all the
 329                          * interpolated steps.
 330                          */
 331                         size = sizeof(*table) * num_levels;
 332                         table = devm_kzalloc(dev, size, GFP_KERNEL);
 333                         if (!table)
 334                                 return -ENOMEM;
 335
 336                         /* Fill the interpolated table. */
 337                         levels_count = 0;
 338                         for (i = 0; i < data->max_brightness - 1; i++) {
 339                                 value = data->levels[i];
 340                                 n = (data->levels[i + 1] - value) / num_steps;
 341                                 if (n > 0) {
 342                                         for (j = 0; j < num_steps; j++) {
 343                                                 table[levels_count] = value;
 344                                                 value += n;
 345                                                 levels_count++;
 346                                         }
 347                                 } else {
 348                                         table[levels_count] = data->levels[i];
 349                                         levels_count++;
 350                                 }
 351                         }
 352                         table[levels_count] = data->levels[i];
 353
 354                         /*
 355                          * As we use interpolation lets remove current
 356                          * brightness levels table and replace for the
 357                          * new interpolated table.
 358                          */
 359                         devm_kfree(dev, data->levels);
 360                         data->levels = table;
 361
 362                         /*
 363                          * Reassign max_brightness value to the new total number
 364                          * of brightness levels.
 365                          */
 366                         data->max_brightness = num_levels;
 367                 }
 368
 369                 data->max_brightness--;
 370         }
 371
 372         return 0;
 373 }
 374
 375 static const struct of_device_id pwm_backlight_of_match[] = {
 376         { .compatible = "pwm-backlight" },
 377         { }
 378 };
 379
 380 MODULE_DEVICE_TABLE(of, pwm_backlight_of_match);
 381 #else
 382 static int pwm_backlight_parse_dt(struct device *dev,
 383                                   struct platform_pwm_backlight_data *data)
 384 {
 385         return -ENODEV;
 386 }
 387
 388 static
 389 int pwm_backlight_brightness_default(struct device *dev,
 390                                      struct platform_pwm_backlight_data *data,
 391                                      unsigned int period)
 392 {
 393         return -ENODEV;
 394 }
 395 #endif
 396
 397 static bool pwm_backlight_is_linear(struct platform_pwm_backlight_data *data)
 398 {
 399         unsigned int nlevels = data->max_brightness + 1;
 400         unsigned int min_val = data->levels[0];
 401         unsigned int max_val = data->levels[nlevels - 1];
 402         /*
 403          * Multiplying by 128 means that even in pathological cases such
 404          * as (max_val - min_val) == nlevels the error at max_val is less
 405          * than 1%.
 406          */
 407         unsigned int slope = (128 * (max_val - min_val)) / nlevels;
 408         unsigned int margin = (max_val - min_val) / 20; /* 5% */
 409         int i;
 410
 411         for (i = 1; i < nlevels; i++) {
 412                 unsigned int linear_value = min_val + ((i * slope) / 128);
 413                 unsigned int delta = abs(linear_value - data->levels[i]);
 414
 415                 if (delta > margin)
 416                         return false;
 417         }
 418
 419         return true;
 420 }
 421
 422 static int pwm_backlight_initial_power_state(const struct pwm_bl_data *pb)
 423 {
 424         struct device_node *node = pb->dev->of_node;
 425
 426         /* Not booted with device tree or no phandle link to the node */
 427         if (!node || !node->phandle)
 428                 return FB_BLANK_UNBLANK;
 429
 430         /*
 431          * If the driver is probed from the device tree and there is a
 432          * phandle link pointing to the backlight node, it is safe to
 433          * assume that another driver will enable the backlight at the
 434          * appropriate time. Therefore, if it is disabled, keep it so.
 435          */
 436
 437         /* if the enable GPIO is disabled, do not enable the backlight */
 438         if (pb->enable_gpio && gpiod_get_value_cansleep(pb->enable_gpio) == 0)
 439                 return FB_BLANK_POWERDOWN;
 440
 441         /* The regulator is disabled, do not enable the backlight */
 442         if (!regulator_is_enabled(pb->power_supply))
 443                 return FB_BLANK_POWERDOWN;
 444
 445         /* The PWM is disabled, keep it like this */
 446         if (!pwm_is_enabled(pb->pwm))
 447                 return FB_BLANK_POWERDOWN;
 448
 449         return FB_BLANK_UNBLANK;
 450 }
 451
 452 static int pwm_backlight_probe(struct platform_device *pdev)
 453 {
 454         struct platform_pwm_backlight_data *data = dev_get_platdata(&pdev->dev);
 455         struct platform_pwm_backlight_data defdata;
 456         struct backlight_properties props;
 457         struct backlight_device *bl;
 458         struct device_node *node = pdev->dev.of_node;
 459         struct pwm_bl_data *pb;
 460         struct pwm_state state;
 461         unsigned int i;
 462         int ret;
 463
 464         if (!data) {
 465                 ret = pwm_backlight_parse_dt(&pdev->dev, &defdata);
 466                 if (ret < 0) {
 467                         dev_err(&pdev->dev, "failed to find platform data\n");
 468                         return ret;
 469                 }
 470
 471                 data = &defdata;
 472         }
 473
 474         if (data->init) {
 475                 ret = data->init(&pdev->dev);
 476                 if (ret < 0)
 477                         return ret;
 478         }
 479
 480         pb = devm_kzalloc(&pdev->dev, sizeof(*pb), GFP_KERNEL);
 481         if (!pb) {
 482                 ret = -ENOMEM;
 483                 goto err_alloc;
 484         }
 485
 486         pb->notify = data->notify;
 487         pb->notify_after = data->notify_after;
 488         pb->check_fb = data->check_fb;
 489         pb->exit = data->exit;
 490         pb->dev = &pdev->dev;
 491         pb->enabled = false;
 492         pb->post_pwm_on_delay = data->post_pwm_on_delay;
 493         pb->pwm_off_delay = data->pwm_off_delay;
 494
 495         pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
 496                                                   GPIOD_ASIS);
 497         if (IS_ERR(pb->enable_gpio)) {
 498                 ret = PTR_ERR(pb->enable_gpio);
 499                 goto err_alloc;
 500         }
 501
 502         /*
 503          * Compatibility fallback for drivers still using the integer GPIO
 504          * platform data. Must go away soon.
 505          */
 506         if (!pb->enable_gpio && gpio_is_valid(data->enable_gpio)) {
 507                 ret = devm_gpio_request_one(&pdev->dev, data->enable_gpio,
 508                                             GPIOF_OUT_INIT_HIGH, "enable");
 509                 if (ret < 0) {
 510                         dev_err(&pdev->dev, "failed to request GPIO#%d: %d\n",
 511                                 data->enable_gpio, ret);
 512                         goto err_alloc;
 513                 }
 514
 515                 pb->enable_gpio = gpio_to_desc(data->enable_gpio);
 516         }
 517
 518         /*
 519          * If the GPIO is not known to be already configured as output, that
 520          * is, if gpiod_get_direction returns either 1 or -EINVAL, change the
 521          * direction to output and set the GPIO as active.
 522          * Do not force the GPIO to active when it was already output as it
 523          * could cause backlight flickering or we would enable the backlight too
 524          * early. Leave the decision of the initial backlight state for later.
 525          */
 526         if (pb->enable_gpio &&
 527             gpiod_get_direction(pb->enable_gpio) != 0)
 528                 gpiod_direction_output(pb->enable_gpio, 1);
 529
 530         pb->power_supply = devm_regulator_get(&pdev->dev, "power");
 531         if (IS_ERR(pb->power_supply)) {
 532                 ret = PTR_ERR(pb->power_supply);
 533                 goto err_alloc;
 534         }
 535
 536         pb->pwm = devm_pwm_get(&pdev->dev, NULL);
 537         if (IS_ERR(pb->pwm) && PTR_ERR(pb->pwm) != -EPROBE_DEFER && !node) {
 538                 dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
 539                 pb->legacy = true;
 540                 pb->pwm = pwm_request(data->pwm_id, "pwm-backlight");
 541         }
 542
 543         if (IS_ERR(pb->pwm)) {
 544                 ret = PTR_ERR(pb->pwm);
 545                 if (ret != -EPROBE_DEFER)
 546                         dev_err(&pdev->dev, "unable to request PWM\n");
 547                 goto err_alloc;
 548         }
 549
 550         dev_dbg(&pdev->dev, "got pwm for backlight\n");
 551
 552         /* Sync up PWM state. */
 553         pwm_init_state(pb->pwm, &state);
 554
 555         /*
 556          * The DT case will set the pwm_period_ns field to 0 and store the
 557          * period, parsed from the DT, in the PWM device. For the non-DT case,
 558          * set the period from platform data if it has not already been set
 559          * via the PWM lookup table.
 560          */
 561         if (!state.period && (data->pwm_period_ns > 0))
 562                 state.period = data->pwm_period_ns;
 563
 564         ret = pwm_apply_state(pb->pwm, &state);
 565         if (ret) {
 566                 dev_err(&pdev->dev, "failed to apply initial PWM state: %d\n",
 567                         ret);
 568                 goto err_alloc;
 569         }
 570
 571         memset(&props, 0, sizeof(struct backlight_properties));
 572
 573         if (data->levels) {
 574                 pb->levels = data->levels;
 575
 576                 /*
 577                  * For the DT case, only when brightness levels is defined
 578                  * data->levels is filled. For the non-DT case, data->levels
 579                  * can come from platform data, however is not usual.
 580                  */
 581                 for (i = 0; i <= data->max_brightness; i++)
 582                         if (data->levels[i] > pb->scale)
 583                                 pb->scale = data->levels[i];
 584
 585                 if (pwm_backlight_is_linear(data))
 586                         props.scale = BACKLIGHT_SCALE_LINEAR;
 587                 else
 588                         props.scale = BACKLIGHT_SCALE_NON_LINEAR;
 589         } else if (!data->max_brightness) {
 590                 /*
 591                  * If no brightness levels are provided and max_brightness is
 592                  * not set, use the default brightness table. For the DT case,
 593                  * max_brightness is set to 0 when brightness levels is not
 594                  * specified. For the non-DT case, max_brightness is usually
 595                  * set to some value.
 596                  */
 597
 598                 /* Get the PWM period (in nanoseconds) */
 599                 pwm_get_state(pb->pwm, &state);
 600
 601                 ret = pwm_backlight_brightness_default(&pdev->dev, data,
 602                                                        state.period);
 603                 if (ret < 0) {
 604                         dev_err(&pdev->dev,
 605                                 "failed to setup default brightness table\n");
 606                         goto err_alloc;
 607                 }
 608
 609                 for (i = 0; i <= data->max_brightness; i++) {
 610                         if (data->levels[i] > pb->scale)
 611                                 pb->scale = data->levels[i];
 612
 613                         pb->levels = data->levels;
 614                 }
 615
 616                 props.scale = BACKLIGHT_SCALE_NON_LINEAR;
 617         } else {
 618                 /*
 619                  * That only happens for the non-DT case, where platform data
 620                  * sets the max_brightness value.
 621                  */
 622                 pb->scale = data->max_brightness;
 623         }
 624
 625         pb->lth_brightness = data->lth_brightness * (state.period / pb->scale);
 626
 627         props.type = BACKLIGHT_RAW;
 628         props.max_brightness = data->max_brightness;
 629         bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
 630                                        &pwm_backlight_ops, &props);
 631         if (IS_ERR(bl)) {
 632                 dev_err(&pdev->dev, "failed to register backlight\n");
 633                 ret = PTR_ERR(bl);
 634                 if (pb->legacy)
 635                         pwm_free(pb->pwm);
 636                 goto err_alloc;
 637         }
 638
 639         if (data->dft_brightness > data->max_brightness) {
 640                 dev_warn(&pdev->dev,
 641                          "invalid default brightness level: %u, using %u\n",
 642                          data->dft_brightness, data->max_brightness);
 643                 data->dft_brightness = data->max_brightness;
 644         }
 645
 646         bl->props.brightness = data->dft_brightness;
 647         bl->props.power = pwm_backlight_initial_power_state(pb);
 648         backlight_update_status(bl);
 649
 650         platform_set_drvdata(pdev, bl);
 651         return 0;
 652
 653 err_alloc:
 654         if (data->exit)
 655                 data->exit(&pdev->dev);
 656         return ret;
 657 }
 658
 659 static int pwm_backlight_remove(struct platform_device *pdev)
 660 {
 661         struct backlight_device *bl = platform_get_drvdata(pdev);
 662         struct pwm_bl_data *pb = bl_get_data(bl);
 663
 664         backlight_device_unregister(bl);
 665         pwm_backlight_power_off(pb);
 666
 667         if (pb->exit)
 668                 pb->exit(&pdev->dev);
 669         if (pb->legacy)
 670                 pwm_free(pb->pwm);
 671
 672         return 0;
 673 }
 674
 675 static void pwm_backlight_shutdown(struct platform_device *pdev)
 676 {
 677         struct backlight_device *bl = platform_get_drvdata(pdev);
 678         struct pwm_bl_data *pb = bl_get_data(bl);
 679
 680         pwm_backlight_power_off(pb);
 681 }
 682
 683 #ifdef CONFIG_PM_SLEEP
 684 static int pwm_backlight_suspend(struct device *dev)
 685 {
 686         struct backlight_device *bl = dev_get_drvdata(dev);
 687         struct pwm_bl_data *pb = bl_get_data(bl);
 688
 689         if (pb->notify)
 690                 pb->notify(pb->dev, 0);
 691
 692         pwm_backlight_power_off(pb);
 693
 694         if (pb->notify_after)
 695                 pb->notify_after(pb->dev, 0);
 696
 697         return 0;
 698 }
 699
 700 static int pwm_backlight_resume(struct device *dev)
 701 {
 702         struct backlight_device *bl = dev_get_drvdata(dev);
 703
 704         backlight_update_status(bl);
 705
 706         return 0;
 707 }
 708 #endif
 709
 710 static const struct dev_pm_ops pwm_backlight_pm_ops = {
 711 #ifdef CONFIG_PM_SLEEP
 712         .suspend = pwm_backlight_suspend,
 713         .resume = pwm_backlight_resume,
 714         .poweroff = pwm_backlight_suspend,
 715         .restore = pwm_backlight_resume,
 716 #endif
 717 };
 718
 719 static struct platform_driver pwm_backlight_driver = {
 720         .driver         = {
 721                 .name           = "pwm-backlight",
 722                 .pm             = &pwm_backlight_pm_ops,
 723                 .of_match_table = of_match_ptr(pwm_backlight_of_match),
 724         },
 725         .probe          = pwm_backlight_probe,
 726         .remove         = pwm_backlight_remove,
 727         .shutdown       = pwm_backlight_shutdown,
 728 };
 729
 730 module_platform_driver(pwm_backlight_driver);
 731
 732 MODULE_DESCRIPTION("PWM based Backlight Driver");
 733 MODULE_LICENSE("GPL v2");
 734 MODULE_ALIAS("platform:pwm-backlight");