pwm_backlight.c
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/*
* Copyright (c) 2016 Google, Inc
* Written by Simon Glass <sjg@chromium.org>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <dm.h>
#include <backlight.h>
#include <pwm.h>
#include <asm/gpio.h>
#include <power/regulator.h>
DECLARE_GLOBAL_DATA_PTR;
struct pwm_backlight_priv {
struct udevice *reg;
struct gpio_desc enable;
struct udevice *pwm;
uint channel;
uint period_ns;
uint default_level;
uint min_level;
uint max_level;
};
static int pwm_backlight_enable(struct udevice *dev)
{
struct pwm_backlight_priv *priv = dev_get_priv(dev);
struct dm_regulator_uclass_platdata *plat;
uint duty_cycle;
int ret;
plat = dev_get_uclass_platdata(priv->reg);
debug("%s: Enable '%s', regulator '%s'/'%s'\n", __func__, dev->name,
priv->reg->name, plat->name);
ret = regulator_set_enable(priv->reg, true);
if (ret) {
debug("%s: Cannot enable regulator for PWM '%s'\n", __func__,
dev->name);
return ret;
}
mdelay(120);
duty_cycle = priv->period_ns * (priv->default_level - priv->min_level) /
(priv->max_level - priv->min_level + 1);
ret = pwm_set_config(priv->pwm, priv->channel, priv->period_ns,
duty_cycle);
if (ret)
return ret;
ret = pwm_set_enable(priv->pwm, priv->channel, true);
if (ret)
return ret;
mdelay(10);
dm_gpio_set_value(&priv->enable, 1);
return 0;
}
static int pwm_backlight_ofdata_to_platdata(struct udevice *dev)
{
struct pwm_backlight_priv *priv = dev_get_priv(dev);
struct ofnode_phandle_args args;
int index, ret, count, len;
const u32 *cell;
debug("%s: start\n", __func__);
ret = uclass_get_device_by_phandle(UCLASS_REGULATOR, dev,
"power-supply", &priv->reg);
if (ret) {
debug("%s: Cannot get power supply: ret=%d\n", __func__, ret);
return ret;
}
ret = gpio_request_by_name(dev, "enable-gpios", 0, &priv->enable,
GPIOD_IS_OUT);
if (ret) {
debug("%s: Warning: cannot get enable GPIO: ret=%d\n",
__func__, ret);
if (ret != -ENOENT)
return ret;
}
ret = dev_read_phandle_with_args(dev, "pwms", "#pwm-cells", 0, 0,
&args);
if (ret) {
debug("%s: Cannot get PWM phandle: ret=%d\n", __func__, ret);
return ret;
}
ret = uclass_get_device_by_ofnode(UCLASS_PWM, args.node, &priv->pwm);
if (ret) {
debug("%s: Cannot get PWM: ret=%d\n", __func__, ret);
return ret;
}
priv->channel = args.args[0];
priv->period_ns = args.args[1];
index = dev_read_u32_default(dev, "default-brightness-level", 255);
cell = dev_read_prop(dev, "brightness-levels", &len);
count = len / sizeof(u32);
if (cell && count > index) {
priv->default_level = fdt32_to_cpu(cell[index]);
priv->max_level = fdt32_to_cpu(cell[count - 1]);
} else {
priv->default_level = index;
priv->max_level = 255;
}
debug("%s: done\n", __func__);
return 0;
}
static int pwm_backlight_probe(struct udevice *dev)
{
return 0;
}
static const struct backlight_ops pwm_backlight_ops = {
.enable = pwm_backlight_enable,
};
static const struct udevice_id pwm_backlight_ids[] = {
{ .compatible = "pwm-backlight" },
{ }
};
U_BOOT_DRIVER(pwm_backlight) = {
.name = "pwm_backlight",
.id = UCLASS_PANEL_BACKLIGHT,
.of_match = pwm_backlight_ids,
.ops = &pwm_backlight_ops,
.ofdata_to_platdata = pwm_backlight_ofdata_to_platdata,
.probe = pwm_backlight_probe,
.priv_auto_alloc_size = sizeof(struct pwm_backlight_priv),
};