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// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (c) 2016 Google, Inc
* Written by Simon Glass <sjg@chromium.org>
*/
#define LOG_CATEGORY UCLASS_PANEL_BACKLIGHT
#include <common.h>
#include <dm.h>
#include <backlight.h>
#include <log.h>
#include <malloc.h>
#include <pwm.h>
#include <asm/gpio.h>
#include <linux/delay.h>
#include <power/regulator.h>
/**
* Private information for the PWM backlight
*
* If @num_levels is 0 then the levels are simple values with the backlight
* value going between the minimum (default 0) and the maximum (default 255).
* Otherwise the levels are an index into @levels (0..n-1).
*
* @reg: Regulator to enable to turn the backlight on (NULL if none)
* @enable, GPIO to set to enable the backlight (can be missing)
* @pwm: PWM to use to change the backlight brightness
* @channel: PWM channel to use
* @period_ns: Period of the backlight in nanoseconds
* @levels: Levels for the backlight, or NULL if not using indexed levels
* @num_levels: Number of levels
* @cur_level: Current level for the backlight (index or value)
* @default_level: Default level for the backlight (index or value)
* @min_level: Minimum level of the backlight (full off)
* @min_level: Maximum level of the backlight (full on)
* @enabled: true if backlight is enabled
*/
struct pwm_backlight_priv {
struct udevice *reg;
struct gpio_desc enable;
struct udevice *pwm;
uint channel;
uint period_ns;
/*
* the polarity of one PWM
* 0: normal polarity
* 1: inverted polarity
*/
bool polarity;
u32 *levels;
int num_levels;
uint default_level;
int cur_level;
uint min_level;
uint max_level;
bool enabled;
};
static int set_pwm(struct pwm_backlight_priv *priv)
{
uint duty_cycle;
int ret;
duty_cycle = priv->period_ns * (priv->cur_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 log_ret(ret);
ret = pwm_set_invert(priv->pwm, priv->channel, priv->polarity);
if (ret == -ENOSYS && !priv->polarity)
ret = 0;
return log_ret(ret);
}
static int enable_sequence(struct udevice *dev, int seq)
{
struct pwm_backlight_priv *priv = dev_get_priv(dev);
int ret;
switch (seq) {
case 0:
if (priv->reg) {
__maybe_unused struct dm_regulator_uclass_platdata
*plat;
plat = dev_get_uclass_platdata(priv->reg);
log_debug("Enable '%s', regulator '%s'/'%s'\n",
dev->name, priv->reg->name, plat->name);
ret = regulator_set_enable(priv->reg, true);
if (ret) {
log_debug("Cannot enable regulator for PWM '%s'\n",
dev->name);
return log_ret(ret);
}
mdelay(120);
}
break;
case 1:
mdelay(10);
dm_gpio_set_value(&priv->enable, 1);
break;
}
return 0;
}
static int pwm_backlight_enable(struct udevice *dev)
{
struct pwm_backlight_priv *priv = dev_get_priv(dev);
int ret;
ret = enable_sequence(dev, 0);
if (ret)
return log_ret(ret);
ret = set_pwm(priv);
if (ret)
return log_ret(ret);
ret = pwm_set_enable(priv->pwm, priv->channel, true);
if (ret)
return log_ret(ret);
ret = enable_sequence(dev, 1);
if (ret)
return log_ret(ret);
priv->enabled = true;
return 0;
}
static int pwm_backlight_set_brightness(struct udevice *dev, int percent)
{
struct pwm_backlight_priv *priv = dev_get_priv(dev);
bool disable = false;
int level;
int ret;
if (!priv->enabled) {
ret = enable_sequence(dev, 0);
if (ret)
return log_ret(ret);
}
if (percent == BACKLIGHT_OFF) {
disable = true;
percent = 0;
}
if (percent == BACKLIGHT_DEFAULT) {
level = priv->default_level;
} else {
if (priv->levels) {
level = priv->levels[percent * (priv->num_levels - 1)
/ 100];
} else {
level = priv->min_level +
(priv->max_level - priv->min_level) *
percent / 100;
}
}
priv->cur_level = level;
ret = set_pwm(priv);
if (ret)
return log_ret(ret);
if (!priv->enabled) {
ret = enable_sequence(dev, 1);
if (ret)
return log_ret(ret);
priv->enabled = true;
}
if (disable) {
dm_gpio_set_value(&priv->enable, 0);
if (priv->reg) {
ret = regulator_set_enable(priv->reg, false);
if (ret)
return log_ret(ret);
}
priv->enabled = false;
}
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;
log_debug("start\n");
ret = uclass_get_device_by_phandle(UCLASS_REGULATOR, dev,
"power-supply", &priv->reg);
if (ret)
log_debug("Cannot get power supply: ret=%d\n", ret);
ret = gpio_request_by_name(dev, "enable-gpios", 0, &priv->enable,
GPIOD_IS_OUT);
if (ret) {
log_debug("Warning: cannot get enable GPIO: ret=%d\n", ret);
if (ret != -ENOENT)
return log_ret(ret);
}
ret = dev_read_phandle_with_args(dev, "pwms", "#pwm-cells", 0, 0,
&args);
if (ret) {
log_debug("Cannot get PWM phandle: ret=%d\n", ret);
return log_ret(ret);
}
ret = uclass_get_device_by_ofnode(UCLASS_PWM, args.node, &priv->pwm);
if (ret) {
log_debug("Cannot get PWM: ret=%d\n", ret);
return log_ret(ret);
}
if (args.args_count < 2)
return log_msg_ret("Not enough arguments to pwm\n", -EINVAL);
priv->channel = args.args[0];
priv->period_ns = args.args[1];
if (args.args_count > 2)
priv->polarity = args.args[2];
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->levels = malloc(len);
if (!priv->levels)
return log_ret(-ENOMEM);
dev_read_u32_array(dev, "brightness-levels", priv->levels,
count);
priv->num_levels = count;
priv->default_level = priv->levels[index];
priv->max_level = priv->levels[count - 1];
} else {
priv->default_level = index;
priv->max_level = 255;
}
priv->cur_level = priv->default_level;
log_debug("done\n");
return 0;
}
static int pwm_backlight_probe(struct udevice *dev)
{
return 0;
}
static const struct backlight_ops pwm_backlight_ops = {
.enable = pwm_backlight_enable,
.set_brightness = pwm_backlight_set_brightness,
};
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),
};
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