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         uint duty_cycle;
  32         int ret;
  33
  34         debug("%s: Enable '%s', regulator '%s'\n", __func__, dev->name,
  35               priv->reg->name);
  36         ret = regulator_set_enable(priv->reg, true);
  37         if (ret) {
  38                 debug("%s: Cannot enable regulator for PWM '%s'\n", __func__,
  39                       dev->name);
  40                 return ret;
  41         }
  42         mdelay(120);
  43
  44         duty_cycle = priv->period_ns * (priv->default_level - priv->min_level) /
  45                 (priv->max_level - priv->min_level + 1);
  46         ret = pwm_set_config(priv->pwm, priv->channel, priv->period_ns,
  47                              duty_cycle);
  48         if (ret)
  49                 return ret;
  50         ret = pwm_set_enable(priv->pwm, priv->channel, true);
  51         if (ret)
  52                 return ret;
  53         mdelay(10);
  54         dm_gpio_set_value(&priv->enable, 1);
  55
  56         return 0;
  57 }
  58
  59 static int pwm_backlight_ofdata_to_platdata(struct udevice *dev)
  60 {
  61         struct pwm_backlight_priv *priv = dev_get_priv(dev);
  62         struct fdtdec_phandle_args args;
  63         const void *blob = gd->fdt_blob;
  64         int node = dev_of_offset(dev);
  65         int index, ret, count, len;
  66         const u32 *cell;
  67
  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                 return ret;
  73         }
  74         ret = gpio_request_by_name(dev, "enable-gpios", 0, &priv->enable,
  75                                    GPIOD_IS_OUT);
  76         if (ret) {
  77                 debug("%s: Warning: cannot get enable GPIO: ret=%d\n",
  78                       __func__, ret);
  79                 if (ret != -ENOENT)
  80                         return ret;
  81         }
  82         ret = fdtdec_parse_phandle_with_args(blob, node, "pwms", "#pwm-cells",
  83                                              0, 0, &args);
  84         if (ret) {
  85                 debug("%s: Cannot get PWM phandle: ret=%d\n", __func__, ret);
  86                 return ret;
  87         }
  88
  89         ret = uclass_get_device_by_of_offset(UCLASS_PWM, args.node, &priv->pwm);
  90         if (ret) {
  91                 debug("%s: Cannot get PWM: ret=%d\n", __func__, ret);
  92                 return ret;
  93         }
  94         priv->channel = args.args[0];
  95         priv->period_ns = args.args[1];
  96
  97         index = fdtdec_get_int(blob, node, "default-brightness-level", 255);
  98         cell = fdt_getprop(blob, node, "brightness-levels", &len);
  99         count = len / sizeof(u32);
 100         if (cell && count > index) {
 101                 priv->default_level = fdt32_to_cpu(cell[index]);
 102                 priv->max_level = fdt32_to_cpu(cell[count - 1]);
 103         } else {
 104                 priv->default_level = index;
 105                 priv->max_level = 255;
 106         }
 107
 108
 109         return 0;
 110 }
 111
 112 static int pwm_backlight_probe(struct udevice *dev)
 113 {
 114         return 0;
 115 }
 116
 117 static const struct backlight_ops pwm_backlight_ops = {
 118         .enable = pwm_backlight_enable,
 119 };
 120
 121 static const struct udevice_id pwm_backlight_ids[] = {
 122         { .compatible = "pwm-backlight" },
 123         { }
 124 };
 125
 126 U_BOOT_DRIVER(pwm_backlight) = {
 127         .name   = "pwm_backlight",
 128         .id     = UCLASS_PANEL_BACKLIGHT,
 129         .of_match = pwm_backlight_ids,
 130         .ops    = &pwm_backlight_ops,
 131         .ofdata_to_platdata     = pwm_backlight_ofdata_to_platdata,
 132         .probe          = pwm_backlight_probe,
 133         .priv_auto_alloc_size   = sizeof(struct pwm_backlight_priv),
 134 };