drivers/video/pwm_backlight.c

   1 /*
   2  * Copyright (c) 2016 Google, Inc
   3  * Written by Simon Glass <sjg@chromium.org>
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8 #include <common.h>
   9 #include <dm.h>
  10 #include <backlight.h>
  11 #include <pwm.h>
  12 #include <asm/gpio.h>
  13 #include <power/regulator.h>
  14
  15 DECLARE_GLOBAL_DATA_PTR;
  16
  17 struct pwm_backlight_priv {
  18         struct udevice *reg;
  19         struct gpio_desc enable;
  20         struct udevice *pwm;
  21         uint channel;
  22         uint period_ns;
  23         uint default_level;
  24         uint min_level;
  25         uint max_level;
  26 };
  27
  28 static int pwm_backlight_enable(struct udevice *dev)
  29 {
  30         struct pwm_backlight_priv *priv = dev_get_priv(dev);
  31         struct dm_regulator_uclass_platdata *plat;
  32         uint duty_cycle;
  33         int ret;
  34
  35         plat = dev_get_uclass_platdata(priv->reg);
  36         debug("%s: Enable '%s', regulator '%s'/'%s'\n", __func__, dev->name,
  37               priv->reg->name, plat->name);
  38         ret = regulator_set_enable(priv->reg, true);
  39         if (ret) {
  40                 debug("%s: Cannot enable regulator for PWM '%s'\n", __func__,
  41                       dev->name);
  42                 return ret;
  43         }
  44         mdelay(120);
  45
  46         duty_cycle = priv->period_ns * (priv->default_level - priv->min_level) /
  47                 (priv->max_level - priv->min_level + 1);
  48         ret = pwm_set_config(priv->pwm, priv->channel, priv->period_ns,
  49                              duty_cycle);
  50         if (ret)
  51                 return ret;
  52         ret = pwm_set_enable(priv->pwm, priv->channel, true);
  53         if (ret)
  54                 return ret;
  55         mdelay(10);
  56         dm_gpio_set_value(&priv->enable, 1);
  57
  58         return 0;
  59 }
  60
  61 static int pwm_backlight_ofdata_to_platdata(struct udevice *dev)
  62 {
  63         struct pwm_backlight_priv *priv = dev_get_priv(dev);
  64         struct ofnode_phandle_args args;
  65         int index, ret, count, len;
  66         const u32 *cell;
  67
  68         debug("%s: start\n", __func__);
  69         ret = uclass_get_device_by_phandle(UCLASS_REGULATOR, dev,
  70                                            "power-supply", &priv->reg);
  71         if (ret) {
  72                 debug("%s: Cannot get power supply: ret=%d\n", __func__, ret);
  73                 return ret;
  74         }
  75         ret = gpio_request_by_name(dev, "enable-gpios", 0, &priv->enable,
  76                                    GPIOD_IS_OUT);
  77         if (ret) {
  78                 debug("%s: Warning: cannot get enable GPIO: ret=%d\n",
  79                       __func__, ret);
  80                 if (ret != -ENOENT)
  81                         return ret;
  82         }
  83         ret = dev_read_phandle_with_args(dev, "pwms", "#pwm-cells", 0, 0,
  84                                          &args);
  85         if (ret) {
  86                 debug("%s: Cannot get PWM phandle: ret=%d\n", __func__, ret);
  87                 return ret;
  88         }
  89
  90         ret = uclass_get_device_by_ofnode(UCLASS_PWM, args.node, &priv->pwm);
  91         if (ret) {
  92                 debug("%s: Cannot get PWM: ret=%d\n", __func__, ret);
  93                 return ret;
  94         }
  95         priv->channel = args.args[0];
  96         priv->period_ns = args.args[1];
  97
  98         index = dev_read_u32_default(dev, "default-brightness-level", 255);
  99         cell = dev_read_prop(dev, "brightness-levels", &len);
 100         count = len / sizeof(u32);
 101         if (cell && count > index) {
 102                 priv->default_level = fdt32_to_cpu(cell[index]);
 103                 priv->max_level = fdt32_to_cpu(cell[count - 1]);
 104         } else {
 105                 priv->default_level = index;
 106                 priv->max_level = 255;
 107         }
 108         debug("%s: done\n", __func__);
 109
 110
 111         return 0;
 112 }
 113
 114 static int pwm_backlight_probe(struct udevice *dev)
 115 {
 116         return 0;
 117 }
 118
 119 static const struct backlight_ops pwm_backlight_ops = {
 120         .enable = pwm_backlight_enable,
 121 };
 122
 123 static const struct udevice_id pwm_backlight_ids[] = {
 124         { .compatible = "pwm-backlight" },
 125         { }
 126 };
 127
 128 U_BOOT_DRIVER(pwm_backlight) = {
 129         .name   = "pwm_backlight",
 130         .id     = UCLASS_PANEL_BACKLIGHT,
 131         .of_match = pwm_backlight_ids,
 132         .ops    = &pwm_backlight_ops,
 133         .ofdata_to_platdata     = pwm_backlight_ofdata_to_platdata,
 134         .probe          = pwm_backlight_probe,
 135         .priv_auto_alloc_size   = sizeof(struct pwm_backlight_priv),
 136 };