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533ad9dcda
The intermediate value could overflow for large periods and levels. Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com> Reviewed-by: Simon Glass <sjg@chromium.org>
279 lines
6.7 KiB
C
279 lines
6.7 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (c) 2016 Google, Inc
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* Written by Simon Glass <sjg@chromium.org>
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*/
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#define LOG_CATEGORY UCLASS_PANEL_BACKLIGHT
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#include <common.h>
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#include <dm.h>
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#include <backlight.h>
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#include <log.h>
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#include <malloc.h>
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#include <pwm.h>
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#include <asm/gpio.h>
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#include <linux/delay.h>
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#include <power/regulator.h>
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/**
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* Private information for the PWM backlight
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*
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* If @num_levels is 0 then the levels are simple values with the backlight
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* value going between the minimum (default 0) and the maximum (default 255).
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* Otherwise the levels are an index into @levels (0..n-1).
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*
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* @reg: Regulator to enable to turn the backlight on (NULL if none)
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* @enable, GPIO to set to enable the backlight (can be missing)
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* @pwm: PWM to use to change the backlight brightness
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* @channel: PWM channel to use
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* @period_ns: Period of the backlight in nanoseconds
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* @levels: Levels for the backlight, or NULL if not using indexed levels
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* @num_levels: Number of levels
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* @cur_level: Current level for the backlight (index or value)
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* @default_level: Default level for the backlight (index or value)
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* @min_level: Minimum level of the backlight (full off)
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* @max_level: Maximum level of the backlight (full on)
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* @enabled: true if backlight is enabled
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*/
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struct pwm_backlight_priv {
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struct udevice *reg;
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struct gpio_desc enable;
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struct udevice *pwm;
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uint channel;
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uint period_ns;
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/*
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* the polarity of one PWM
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* 0: normal polarity
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* 1: inverted polarity
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*/
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bool polarity;
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u32 *levels;
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int num_levels;
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uint default_level;
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int cur_level;
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uint min_level;
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uint max_level;
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bool enabled;
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};
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static int set_pwm(struct pwm_backlight_priv *priv)
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{
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uint duty_cycle;
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int ret;
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if (priv->period_ns) {
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duty_cycle = (u64)priv->period_ns * (priv->cur_level - priv->min_level) /
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(priv->max_level - priv->min_level);
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ret = pwm_set_config(priv->pwm, priv->channel, priv->period_ns,
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duty_cycle);
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} else {
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/* PWM driver will internally scale these like the above. */
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ret = pwm_set_config(priv->pwm, priv->channel,
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priv->max_level - priv->min_level,
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priv->cur_level - priv->min_level);
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}
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if (ret)
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return log_ret(ret);
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ret = pwm_set_invert(priv->pwm, priv->channel, priv->polarity);
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if (ret == -ENOSYS && !priv->polarity)
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ret = 0;
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return log_ret(ret);
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}
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static int enable_sequence(struct udevice *dev, int seq)
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{
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struct pwm_backlight_priv *priv = dev_get_priv(dev);
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int ret;
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switch (seq) {
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case 0:
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if (priv->reg) {
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__maybe_unused struct dm_regulator_uclass_plat
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*plat;
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plat = dev_get_uclass_plat(priv->reg);
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log_debug("Enable '%s', regulator '%s'/'%s'\n",
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dev->name, priv->reg->name, plat->name);
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ret = regulator_set_enable(priv->reg, true);
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if (ret) {
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log_debug("Cannot enable regulator for PWM '%s'\n",
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dev->name);
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return log_ret(ret);
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}
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mdelay(120);
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}
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break;
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case 1:
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mdelay(10);
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dm_gpio_set_value(&priv->enable, 1);
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break;
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}
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return 0;
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}
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static int pwm_backlight_enable(struct udevice *dev)
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{
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struct pwm_backlight_priv *priv = dev_get_priv(dev);
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int ret;
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ret = enable_sequence(dev, 0);
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if (ret)
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return log_ret(ret);
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ret = set_pwm(priv);
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if (ret)
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return log_ret(ret);
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ret = pwm_set_enable(priv->pwm, priv->channel, true);
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if (ret)
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return log_ret(ret);
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ret = enable_sequence(dev, 1);
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if (ret)
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return log_ret(ret);
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priv->enabled = true;
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return 0;
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}
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static int pwm_backlight_set_brightness(struct udevice *dev, int percent)
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{
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struct pwm_backlight_priv *priv = dev_get_priv(dev);
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bool disable = false;
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int level;
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int ret;
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if (!priv->enabled) {
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ret = enable_sequence(dev, 0);
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if (ret)
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return log_ret(ret);
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}
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if (percent == BACKLIGHT_OFF) {
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disable = true;
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percent = 0;
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}
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if (percent == BACKLIGHT_DEFAULT) {
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level = priv->default_level;
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} else {
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if (priv->levels) {
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level = priv->levels[percent * (priv->num_levels - 1)
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/ 100];
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} else {
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level = priv->min_level +
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(priv->max_level - priv->min_level) *
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percent / 100;
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}
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}
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priv->cur_level = level;
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ret = set_pwm(priv);
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if (ret)
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return log_ret(ret);
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if (!priv->enabled) {
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ret = enable_sequence(dev, 1);
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if (ret)
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return log_ret(ret);
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priv->enabled = true;
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}
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if (disable) {
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dm_gpio_set_value(&priv->enable, 0);
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if (priv->reg) {
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ret = regulator_set_enable(priv->reg, false);
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if (ret)
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return log_ret(ret);
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}
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priv->enabled = false;
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}
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return 0;
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}
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static int pwm_backlight_of_to_plat(struct udevice *dev)
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{
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struct pwm_backlight_priv *priv = dev_get_priv(dev);
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struct ofnode_phandle_args args;
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int index, ret, count, len;
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const u32 *cell;
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log_debug("start\n");
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ret = uclass_get_device_by_phandle(UCLASS_REGULATOR, dev,
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"power-supply", &priv->reg);
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if (ret)
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log_debug("Cannot get power supply: ret=%d\n", ret);
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ret = gpio_request_by_name(dev, "enable-gpios", 0, &priv->enable,
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GPIOD_IS_OUT);
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if (ret) {
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log_debug("Warning: cannot get enable GPIO: ret=%d\n", ret);
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if (ret != -ENOENT)
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return log_ret(ret);
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}
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ret = dev_read_phandle_with_args(dev, "pwms", "#pwm-cells", 0, 0,
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&args);
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if (ret) {
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log_debug("Cannot get PWM phandle: ret=%d\n", ret);
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return log_ret(ret);
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}
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ret = uclass_get_device_by_ofnode(UCLASS_PWM, args.node, &priv->pwm);
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if (ret) {
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log_debug("Cannot get PWM: ret=%d\n", ret);
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return log_ret(ret);
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}
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if (args.args_count < 1)
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return log_msg_ret("Not enough arguments to pwm\n", -EINVAL);
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priv->channel = args.args[0];
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if (args.args_count > 1)
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priv->period_ns = args.args[1];
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if (args.args_count > 2)
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priv->polarity = args.args[2];
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index = dev_read_u32_default(dev, "default-brightness-level", 255);
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cell = dev_read_prop(dev, "brightness-levels", &len);
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count = len / sizeof(u32);
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if (cell && count > index) {
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priv->levels = malloc(len);
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if (!priv->levels)
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return log_ret(-ENOMEM);
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ret = dev_read_u32_array(dev, "brightness-levels", priv->levels,
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count);
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if (ret)
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return log_msg_ret("levels", ret);
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priv->num_levels = count;
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priv->default_level = priv->levels[index];
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priv->max_level = priv->levels[count - 1];
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} else {
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priv->default_level = index;
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priv->max_level = 255;
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}
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priv->cur_level = priv->default_level;
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log_debug("done\n");
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return 0;
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}
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static int pwm_backlight_probe(struct udevice *dev)
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{
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return 0;
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}
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static const struct backlight_ops pwm_backlight_ops = {
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.enable = pwm_backlight_enable,
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.set_brightness = pwm_backlight_set_brightness,
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};
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static const struct udevice_id pwm_backlight_ids[] = {
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{ .compatible = "pwm-backlight" },
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{ }
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};
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U_BOOT_DRIVER(pwm_backlight) = {
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.name = "pwm_backlight",
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.id = UCLASS_PANEL_BACKLIGHT,
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.of_match = pwm_backlight_ids,
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.ops = &pwm_backlight_ops,
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.of_to_plat = pwm_backlight_of_to_plat,
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.probe = pwm_backlight_probe,
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.priv_auto = sizeof(struct pwm_backlight_priv),
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};
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