drivers/video/pwm_backlight.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (c) 2016 Google, Inc
   4  * Written by Simon Glass <sjg@chromium.org>
   5  */
   6
   7 #include <common.h>
   8 #include <dm.h>
   9 #include <backlight.h>
  10 #include <pwm.h>
  11 #include <asm/gpio.h>
  12 #include <power/regulator.h>
  13
  14 struct pwm_backlight_priv {
  15         struct udevice *reg;
  16         struct gpio_desc enable;
  17         struct udevice *pwm;
  18         uint channel;
  19         uint period_ns;
  20         uint default_level;
  21         uint min_level;
  22         uint max_level;
  23 };
  24
  25 static int pwm_backlight_enable(struct udevice *dev)
  26 {
  27         struct pwm_backlight_priv *priv = dev_get_priv(dev);
  28         struct dm_regulator_uclass_platdata *plat;
  29         uint duty_cycle;
  30         int ret;
  31
  32         if (priv->reg) {
  33                 plat = dev_get_uclass_platdata(priv->reg);
  34                 debug("%s: Enable '%s', regulator '%s'/'%s'\n", __func__,
  35                       dev->name, priv->reg->name, plat->name);
  36                 ret = regulator_set_enable(priv->reg, true);
  37                 if (ret) {
  38                         debug("%s: Cannot enable regulator for PWM '%s'\n",
  39                               __func__, dev->name);
  40                         return ret;
  41                 }
  42                 mdelay(120);
  43         }
  44
  45         duty_cycle = priv->period_ns * (priv->default_level - priv->min_level) /
  46                 (priv->max_level - priv->min_level + 1);
  47         ret = pwm_set_config(priv->pwm, priv->channel, priv->period_ns,
  48                              duty_cycle);
  49         if (ret)
  50                 return ret;
  51         ret = pwm_set_enable(priv->pwm, priv->channel, true);
  52         if (ret)
  53                 return ret;
  54         mdelay(10);
  55         dm_gpio_set_value(&priv->enable, 1);
  56
  57         return 0;
  58 }
  59
  60 static int pwm_backlight_ofdata_to_platdata(struct udevice *dev)
  61 {
  62         struct pwm_backlight_priv *priv = dev_get_priv(dev);
  63         struct ofnode_phandle_args args;
  64         int index, ret, count, len;
  65         const u32 *cell;
  66
  67         debug("%s: start\n", __func__);
  68         ret = uclass_get_device_by_phandle(UCLASS_REGULATOR, dev,
  69                                            "power-supply", &priv->reg);
  70         if (ret)
  71                 debug("%s: Cannot get power supply: ret=%d\n", __func__, ret);
  72         ret = gpio_request_by_name(dev, "enable-gpios", 0, &priv->enable,
  73                                    GPIOD_IS_OUT);
  74         if (ret) {
  75                 debug("%s: Warning: cannot get enable GPIO: ret=%d\n",
  76                       __func__, ret);
  77                 if (ret != -ENOENT)
  78                         return ret;
  79         }
  80         ret = dev_read_phandle_with_args(dev, "pwms", "#pwm-cells", 0, 0,
  81                                          &args);
  82         if (ret) {
  83                 debug("%s: Cannot get PWM phandle: ret=%d\n", __func__, ret);
  84                 return ret;
  85         }
  86
  87         ret = uclass_get_device_by_ofnode(UCLASS_PWM, args.node, &priv->pwm);
  88         if (ret) {
  89                 debug("%s: Cannot get PWM: ret=%d\n", __func__, ret);
  90                 return ret;
  91         }
  92         priv->channel = args.args[0];
  93         priv->period_ns = args.args[1];
  94
  95         index = dev_read_u32_default(dev, "default-brightness-level", 255);
  96         cell = dev_read_prop(dev, "brightness-levels", &len);
  97         count = len / sizeof(u32);
  98         if (cell && count > index) {
  99                 priv->default_level = fdt32_to_cpu(cell[index]);
 100                 priv->max_level = fdt32_to_cpu(cell[count - 1]);
 101         } else {
 102                 priv->default_level = index;
 103                 priv->max_level = 255;
 104         }
 105         debug("%s: done\n", __func__);
 106
 107
 108         return 0;
 109 }
 110
 111 static int pwm_backlight_probe(struct udevice *dev)
 112 {
 113         return 0;
 114 }
 115
 116 static const struct backlight_ops pwm_backlight_ops = {
 117         .enable = pwm_backlight_enable,
 118 };
 119
 120 static const struct udevice_id pwm_backlight_ids[] = {
 121         { .compatible = "pwm-backlight" },
 122         { }
 123 };
 124
 125 U_BOOT_DRIVER(pwm_backlight) = {
 126         .name   = "pwm_backlight",
 127         .id     = UCLASS_PANEL_BACKLIGHT,
 128         .of_match = pwm_backlight_ids,
 129         .ops    = &pwm_backlight_ops,
 130         .ofdata_to_platdata     = pwm_backlight_ofdata_to_platdata,
 131         .probe          = pwm_backlight_probe,
 132         .priv_auto_alloc_size   = sizeof(struct pwm_backlight_priv),
 133 };