forked from Minki/linux
Split adjustment of the brightness (by changing the PWM duty cycle) from the power on sequence. This fixes an issue where the brightness can no longer be updated once the backlight has been enabled. Reported-by: Marc Dietrich <marvin24@gmx.de> Signed-off-by: Thierry Reding <treding@nvidia.com>
409 lines
9.6 KiB
C
409 lines
9.6 KiB
C
/*
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* linux/drivers/video/backlight/pwm_bl.c
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*
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* simple PWM based backlight control, board code has to setup
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* 1) pin configuration so PWM waveforms can output
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* 2) platform_data being correctly configured
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/gpio.h>
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#include <linux/of_gpio.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <linux/fb.h>
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#include <linux/backlight.h>
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#include <linux/err.h>
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#include <linux/pwm.h>
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#include <linux/pwm_backlight.h>
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#include <linux/regulator/consumer.h>
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#include <linux/slab.h>
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struct pwm_bl_data {
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struct pwm_device *pwm;
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struct device *dev;
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unsigned int period;
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unsigned int lth_brightness;
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unsigned int *levels;
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bool enabled;
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struct regulator *power_supply;
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int enable_gpio;
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unsigned long enable_gpio_flags;
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unsigned int scale;
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int (*notify)(struct device *,
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int brightness);
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void (*notify_after)(struct device *,
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int brightness);
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int (*check_fb)(struct device *, struct fb_info *);
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void (*exit)(struct device *);
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};
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static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
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{
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int duty_cycle, err;
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if (pb->enabled)
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return;
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err = regulator_enable(pb->power_supply);
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if (err < 0)
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dev_err(pb->dev, "failed to enable power supply\n");
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if (gpio_is_valid(pb->enable_gpio)) {
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if (pb->enable_gpio_flags & PWM_BACKLIGHT_GPIO_ACTIVE_LOW)
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gpio_set_value(pb->enable_gpio, 0);
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else
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gpio_set_value(pb->enable_gpio, 1);
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}
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pwm_enable(pb->pwm);
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pb->enabled = true;
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}
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static void pwm_backlight_power_off(struct pwm_bl_data *pb)
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{
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if (!pb->enabled)
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return;
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pwm_config(pb->pwm, 0, pb->period);
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pwm_disable(pb->pwm);
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if (gpio_is_valid(pb->enable_gpio)) {
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if (pb->enable_gpio_flags & PWM_BACKLIGHT_GPIO_ACTIVE_LOW)
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gpio_set_value(pb->enable_gpio, 1);
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else
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gpio_set_value(pb->enable_gpio, 0);
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}
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regulator_disable(pb->power_supply);
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pb->enabled = false;
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}
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static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)
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{
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unsigned int lth = pb->lth_brightness;
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int duty_cycle;
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if (pb->levels)
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duty_cycle = pb->levels[brightness];
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else
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duty_cycle = brightness;
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return (duty_cycle * (pb->period - lth) / pb->scale) + lth;
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}
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static int pwm_backlight_update_status(struct backlight_device *bl)
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{
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struct pwm_bl_data *pb = bl_get_data(bl);
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int brightness = bl->props.brightness;
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int duty_cycle;
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if (bl->props.power != FB_BLANK_UNBLANK ||
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bl->props.fb_blank != FB_BLANK_UNBLANK ||
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bl->props.state & BL_CORE_FBBLANK)
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brightness = 0;
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if (pb->notify)
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brightness = pb->notify(pb->dev, brightness);
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if (brightness > 0) {
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duty_cycle = compute_duty_cycle(pb, brightness);
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pwm_config(pb->pwm, duty_cycle, pb->period);
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pwm_backlight_power_on(pb, brightness);
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} else
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pwm_backlight_power_off(pb);
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if (pb->notify_after)
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pb->notify_after(pb->dev, brightness);
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return 0;
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}
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static int pwm_backlight_get_brightness(struct backlight_device *bl)
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{
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return bl->props.brightness;
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}
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static int pwm_backlight_check_fb(struct backlight_device *bl,
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struct fb_info *info)
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{
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struct pwm_bl_data *pb = bl_get_data(bl);
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return !pb->check_fb || pb->check_fb(pb->dev, info);
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}
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static const struct backlight_ops pwm_backlight_ops = {
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.update_status = pwm_backlight_update_status,
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.get_brightness = pwm_backlight_get_brightness,
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.check_fb = pwm_backlight_check_fb,
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};
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#ifdef CONFIG_OF
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static int pwm_backlight_parse_dt(struct device *dev,
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struct platform_pwm_backlight_data *data)
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{
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struct device_node *node = dev->of_node;
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enum of_gpio_flags flags;
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struct property *prop;
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int length;
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u32 value;
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int ret;
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if (!node)
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return -ENODEV;
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memset(data, 0, sizeof(*data));
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/* determine the number of brightness levels */
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prop = of_find_property(node, "brightness-levels", &length);
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if (!prop)
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return -EINVAL;
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data->max_brightness = length / sizeof(u32);
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/* read brightness levels from DT property */
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if (data->max_brightness > 0) {
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size_t size = sizeof(*data->levels) * data->max_brightness;
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data->levels = devm_kzalloc(dev, size, GFP_KERNEL);
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if (!data->levels)
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return -ENOMEM;
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ret = of_property_read_u32_array(node, "brightness-levels",
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data->levels,
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data->max_brightness);
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if (ret < 0)
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return ret;
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ret = of_property_read_u32(node, "default-brightness-level",
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&value);
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if (ret < 0)
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return ret;
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data->dft_brightness = value;
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data->max_brightness--;
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}
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data->enable_gpio = of_get_named_gpio_flags(node, "enable-gpios", 0,
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&flags);
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if (data->enable_gpio == -EPROBE_DEFER)
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return -EPROBE_DEFER;
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if (gpio_is_valid(data->enable_gpio) && (flags & OF_GPIO_ACTIVE_LOW))
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data->enable_gpio_flags |= PWM_BACKLIGHT_GPIO_ACTIVE_LOW;
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return 0;
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}
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static struct of_device_id pwm_backlight_of_match[] = {
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{ .compatible = "pwm-backlight" },
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{ }
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};
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MODULE_DEVICE_TABLE(of, pwm_backlight_of_match);
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#else
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static int pwm_backlight_parse_dt(struct device *dev,
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struct platform_pwm_backlight_data *data)
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{
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return -ENODEV;
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}
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#endif
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static int pwm_backlight_probe(struct platform_device *pdev)
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{
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struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
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struct platform_pwm_backlight_data defdata;
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struct backlight_properties props;
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struct backlight_device *bl;
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struct pwm_bl_data *pb;
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int ret;
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if (!data) {
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ret = pwm_backlight_parse_dt(&pdev->dev, &defdata);
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if (ret < 0) {
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dev_err(&pdev->dev, "failed to find platform data\n");
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return ret;
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}
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data = &defdata;
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}
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if (data->init) {
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ret = data->init(&pdev->dev);
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if (ret < 0)
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return ret;
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}
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pb = devm_kzalloc(&pdev->dev, sizeof(*pb), GFP_KERNEL);
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if (!pb) {
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dev_err(&pdev->dev, "no memory for state\n");
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ret = -ENOMEM;
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goto err_alloc;
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}
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if (data->levels) {
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unsigned int i;
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for (i = 0; i <= data->max_brightness; i++)
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if (data->levels[i] > pb->scale)
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pb->scale = data->levels[i];
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pb->levels = data->levels;
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} else
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pb->scale = data->max_brightness;
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pb->enable_gpio = data->enable_gpio;
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pb->enable_gpio_flags = data->enable_gpio_flags;
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pb->notify = data->notify;
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pb->notify_after = data->notify_after;
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pb->check_fb = data->check_fb;
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pb->exit = data->exit;
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pb->dev = &pdev->dev;
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pb->enabled = false;
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if (gpio_is_valid(pb->enable_gpio)) {
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unsigned long flags;
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if (pb->enable_gpio_flags & PWM_BACKLIGHT_GPIO_ACTIVE_LOW)
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flags = GPIOF_OUT_INIT_HIGH;
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else
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flags = GPIOF_OUT_INIT_LOW;
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ret = gpio_request_one(pb->enable_gpio, flags, "enable");
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if (ret < 0) {
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dev_err(&pdev->dev, "failed to request GPIO#%d: %d\n",
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pb->enable_gpio, ret);
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goto err_alloc;
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}
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}
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pb->power_supply = devm_regulator_get(&pdev->dev, "power");
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if (IS_ERR(pb->power_supply)) {
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ret = PTR_ERR(pb->power_supply);
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goto err_gpio;
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}
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pb->pwm = devm_pwm_get(&pdev->dev, NULL);
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if (IS_ERR(pb->pwm)) {
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dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
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pb->pwm = pwm_request(data->pwm_id, "pwm-backlight");
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if (IS_ERR(pb->pwm)) {
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dev_err(&pdev->dev, "unable to request legacy PWM\n");
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ret = PTR_ERR(pb->pwm);
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goto err_gpio;
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}
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}
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dev_dbg(&pdev->dev, "got pwm for backlight\n");
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/*
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* The DT case will set the pwm_period_ns field to 0 and store the
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* period, parsed from the DT, in the PWM device. For the non-DT case,
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* set the period from platform data.
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*/
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if (data->pwm_period_ns > 0)
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pwm_set_period(pb->pwm, data->pwm_period_ns);
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pb->period = pwm_get_period(pb->pwm);
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pb->lth_brightness = data->lth_brightness * (pb->period / pb->scale);
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memset(&props, 0, sizeof(struct backlight_properties));
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props.type = BACKLIGHT_RAW;
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props.max_brightness = data->max_brightness;
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bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
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&pwm_backlight_ops, &props);
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if (IS_ERR(bl)) {
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dev_err(&pdev->dev, "failed to register backlight\n");
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ret = PTR_ERR(bl);
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goto err_gpio;
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}
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if (data->dft_brightness > data->max_brightness) {
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dev_warn(&pdev->dev,
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"invalid default brightness level: %u, using %u\n",
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data->dft_brightness, data->max_brightness);
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data->dft_brightness = data->max_brightness;
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}
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bl->props.brightness = data->dft_brightness;
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backlight_update_status(bl);
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platform_set_drvdata(pdev, bl);
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return 0;
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err_gpio:
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if (gpio_is_valid(pb->enable_gpio))
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gpio_free(pb->enable_gpio);
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err_alloc:
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if (data->exit)
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data->exit(&pdev->dev);
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return ret;
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}
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static int pwm_backlight_remove(struct platform_device *pdev)
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{
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struct backlight_device *bl = platform_get_drvdata(pdev);
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struct pwm_bl_data *pb = bl_get_data(bl);
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backlight_device_unregister(bl);
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pwm_backlight_power_off(pb);
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if (pb->exit)
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pb->exit(&pdev->dev);
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return 0;
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}
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#ifdef CONFIG_PM_SLEEP
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static int pwm_backlight_suspend(struct device *dev)
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{
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struct backlight_device *bl = dev_get_drvdata(dev);
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struct pwm_bl_data *pb = bl_get_data(bl);
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if (pb->notify)
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pb->notify(pb->dev, 0);
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pwm_backlight_power_off(pb);
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if (pb->notify_after)
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pb->notify_after(pb->dev, 0);
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return 0;
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}
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static int pwm_backlight_resume(struct device *dev)
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{
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struct backlight_device *bl = dev_get_drvdata(dev);
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backlight_update_status(bl);
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return 0;
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}
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#endif
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static SIMPLE_DEV_PM_OPS(pwm_backlight_pm_ops, pwm_backlight_suspend,
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pwm_backlight_resume);
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static struct platform_driver pwm_backlight_driver = {
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.driver = {
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.name = "pwm-backlight",
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.owner = THIS_MODULE,
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.pm = &pwm_backlight_pm_ops,
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.of_match_table = of_match_ptr(pwm_backlight_of_match),
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},
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.probe = pwm_backlight_probe,
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.remove = pwm_backlight_remove,
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};
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module_platform_driver(pwm_backlight_driver);
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MODULE_DESCRIPTION("PWM based Backlight Driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:pwm-backlight");
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