460 lines
11 KiB
C
460 lines
11 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/consumer.h>
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#include <linux/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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struct gpio_desc *enable_gpio;
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unsigned int scale;
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bool legacy;
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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 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 (pb->enable_gpio)
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gpiod_set_value_cansleep(pb->enable_gpio, 1);
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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 (pb->enable_gpio)
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gpiod_set_value_cansleep(pb->enable_gpio, 0);
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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_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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.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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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 = -EINVAL;
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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_initial_power_state(const struct pwm_bl_data *pb)
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{
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struct device_node *node = pb->dev->of_node;
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/* Not booted with device tree or no phandle link to the node */
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if (!node || !node->phandle)
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return FB_BLANK_UNBLANK;
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/*
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* If the driver is probed from the device tree and there is a
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* phandle link pointing to the backlight node, it is safe to
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* assume that another driver will enable the backlight at the
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* appropriate time. Therefore, if it is disabled, keep it so.
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*/
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/* if the enable GPIO is disabled, do not enable the backlight */
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if (pb->enable_gpio && gpiod_get_value(pb->enable_gpio) == 0)
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return FB_BLANK_POWERDOWN;
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/* The regulator is disabled, do not enable the backlight */
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if (!regulator_is_enabled(pb->power_supply))
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return FB_BLANK_POWERDOWN;
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/* The PWM is disabled, keep it like this */
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if (!pwm_is_enabled(pb->pwm))
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return FB_BLANK_POWERDOWN;
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return FB_BLANK_UNBLANK;
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}
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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 = dev_get_platdata(&pdev->dev);
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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 device_node *node = pdev->dev.of_node;
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struct pwm_bl_data *pb;
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struct pwm_args pargs;
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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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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->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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pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
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GPIOD_ASIS);
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if (IS_ERR(pb->enable_gpio)) {
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ret = PTR_ERR(pb->enable_gpio);
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goto err_alloc;
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}
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/*
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* Compatibility fallback for drivers still using the integer GPIO
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* platform data. Must go away soon.
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*/
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if (!pb->enable_gpio && gpio_is_valid(data->enable_gpio)) {
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ret = devm_gpio_request_one(&pdev->dev, data->enable_gpio,
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GPIOF_OUT_INIT_HIGH, "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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data->enable_gpio, ret);
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goto err_alloc;
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}
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pb->enable_gpio = gpio_to_desc(data->enable_gpio);
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}
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/*
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* If the GPIO is configured as input, change the direction to output
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* and set the GPIO as active.
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* Do not force the GPIO to active when it was already output as it
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* could cause backlight flickering or we would enable the backlight too
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* early. Leave the decision of the initial backlight state for later.
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*/
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if (pb->enable_gpio &&
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gpiod_get_direction(pb->enable_gpio) == GPIOF_DIR_IN)
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gpiod_direction_output(pb->enable_gpio, 1);
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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_alloc;
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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) && PTR_ERR(pb->pwm) != -EPROBE_DEFER && !node) {
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dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
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pb->legacy = true;
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pb->pwm = pwm_request(data->pwm_id, "pwm-backlight");
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}
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if (IS_ERR(pb->pwm)) {
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ret = PTR_ERR(pb->pwm);
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if (ret != -EPROBE_DEFER)
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dev_err(&pdev->dev, "unable to request PWM\n");
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goto err_alloc;
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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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* FIXME: pwm_apply_args() should be removed when switching to
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* the atomic PWM API.
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*/
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pwm_apply_args(pb->pwm);
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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 if it has not already been set
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* via the PWM lookup table.
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*/
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pwm_get_args(pb->pwm, &pargs);
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pb->period = pargs.period;
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if (!pb->period && (data->pwm_period_ns > 0))
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pb->period = data->pwm_period_ns;
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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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if (pb->legacy)
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pwm_free(pb->pwm);
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goto err_alloc;
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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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bl->props.power = pwm_backlight_initial_power_state(pb);
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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_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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if (pb->legacy)
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pwm_free(pb->pwm);
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return 0;
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}
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static void pwm_backlight_shutdown(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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pwm_backlight_power_off(pb);
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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 const struct dev_pm_ops pwm_backlight_pm_ops = {
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#ifdef CONFIG_PM_SLEEP
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.suspend = pwm_backlight_suspend,
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.resume = pwm_backlight_resume,
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.poweroff = pwm_backlight_suspend,
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.restore = pwm_backlight_resume,
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#endif
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};
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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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.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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.shutdown = pwm_backlight_shutdown,
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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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