507 lines
12 KiB
C
507 lines
12 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/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/slab.h>
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#include <linux/gpio.h>
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#include <linux/of_gpio.h>
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struct pwm_bl_alt_brightness_table {
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const char *identifier;
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unsigned int *levels;
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};
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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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struct pwm_bl_alt_brightness_table *alt_brightness_tables;
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unsigned int num_alt_brightness_tables;
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int enable_gpio;
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bool gpio_invert;
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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_gpio_set(struct pwm_bl_data *pb, bool enable)
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{
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int val;
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if (gpio_is_valid(pb->enable_gpio)) {
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if (enable)
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val = !pb->gpio_invert;
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else
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val = pb->gpio_invert;
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gpio_direction_output(pb->enable_gpio, val);
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}
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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 max = bl->props.max_brightness;
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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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pwm_config(pb->pwm, 0, pb->period);
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pwm_disable(pb->pwm);
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pwm_backlight_gpio_set(pb, false);
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} else {
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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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max = pb->levels[max];
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} else {
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duty_cycle = brightness;
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}
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duty_cycle = pb->lth_brightness +
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(duty_cycle * (pb->period - pb->lth_brightness) / max);
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pwm_config(pb->pwm, duty_cycle, pb->period);
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pwm_enable(pb->pwm);
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pwm_backlight_gpio_set(pb, true);
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}
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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 int pwm_backlight_choose(struct backlight_device *bl,
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char *identifier)
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{
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struct pwm_bl_data *pb = bl_get_data(bl);
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struct pwm_bl_alt_brightness_table *table = NULL;
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int table_index;
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if (!pb->alt_brightness_tables)
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return -EINVAL;
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for (table_index = 0;
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table_index < pb->num_alt_brightness_tables;
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table_index++)
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if (strcmp(pb->alt_brightness_tables[table_index].identifier,
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identifier) == 0) {
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table = &pb->alt_brightness_tables[table_index];
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break;
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}
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if (!table)
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return -EINVAL;
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memcpy(pb->levels, table->levels,
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sizeof(*table->levels) * (bl->props.max_brightness + 1));
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pwm_backlight_update_status(bl);
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dev_info(pb->dev, "Chose %s\n", identifier);
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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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.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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.choose = pwm_backlight_choose,
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};
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#ifdef CONFIG_OF
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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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enum of_gpio_flags flags;
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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-gpio", 0,
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&flags);
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if (gpio_is_valid(data->enable_gpio) && (flags & OF_GPIO_ACTIVE_LOW))
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data->gpio_invert = true;
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return 0;
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}
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static void pwm_backlight_alt_brightness_table_parse_dt(struct device *dev,
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struct pwm_bl_data *pb)
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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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struct device_node *iter;
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int default_length;
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int table_index;
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prop = of_find_property(node, "brightness-levels", &default_length);
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if (!prop)
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return;
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/* Determine the number of alternate brightness level tables */
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for_each_child_of_node(node, iter)
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if (of_device_is_compatible(iter,
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"pwm-backlight-alt-brightness-levels"))
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pb->num_alt_brightness_tables++;
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if (pb->num_alt_brightness_tables == 0)
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return;
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pb->alt_brightness_tables = devm_kzalloc(dev,
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sizeof(struct pwm_bl_alt_brightness_table) *
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pb->num_alt_brightness_tables,
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GFP_KERNEL);
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if (!pb->alt_brightness_tables)
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return;
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/* Read in each alternate brightness level table */
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table_index = 0;
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for_each_child_of_node(node, iter) {
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struct pwm_bl_alt_brightness_table *table =
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&pb->alt_brightness_tables[table_index];
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struct property *prop;
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int length;
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int max_brightness;
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size_t size;
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int ret;
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/*
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* Read in the identifier that will be used to select the
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* table.
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*/
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ret = of_property_read_string(iter, "identifier",
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&table->identifier);
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if (ret < 0)
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goto fail;
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/*
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* Determine the number of brightness levels. All of the
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* alternate brightness tables must be of the same length
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* as the default one.
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*/
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prop = of_find_property(iter, "brightness-levels", &length);
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max_brightness = length / sizeof(u32);
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size = sizeof(*table->levels) * max_brightness;
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if (size != default_length)
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goto fail;
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table->levels = devm_kzalloc(dev, size, GFP_KERNEL);
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if (!table->levels)
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goto fail;
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/* Finally, read in the alternate table. */
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ret = of_property_read_u32_array(iter, "brightness-levels",
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table->levels,
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max_brightness);
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if (ret < 0)
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goto fail;
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table_index++;
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}
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dev_notice(dev, "Read in %d alternate brightness tables\n",
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pb->num_alt_brightness_tables);
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return;
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fail:
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dev_notice(dev, "Failed reading alternate brightness tables\n");
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/*
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* If we fail for whatever reason, roll back the alternate brightness
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* level tables' allocations.
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*/
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for (table_index = 0;
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table_index < pb->num_alt_brightness_tables;
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table_index++) {
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struct pwm_bl_alt_brightness_table *table =
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&pb->alt_brightness_tables[table_index];
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/*
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* table->identifier is not actually allocated by us, so don't
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* worry about it here.
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*/
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if (table->levels)
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devm_kfree(dev, table->levels);
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}
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devm_kfree(dev, pb->alt_brightness_tables);
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pb->alt_brightness_tables = NULL;
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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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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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static void pwm_backlight_alt_brightness_table_parse_dt(struct device *dev,
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struct pwm_bl_data *pb)
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{
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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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unsigned int max;
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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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max = data->levels[data->max_brightness];
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pb->levels = data->levels;
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} else
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max = data->max_brightness;
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if (gpio_is_valid(data->enable_gpio)) {
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ret = devm_gpio_request(&pdev->dev, data->enable_gpio,
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"pwm-bl-en");
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if (ret) {
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dev_err(&pdev->dev, "unable to request enable GPIO\n");
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goto err_alloc;
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}
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}
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pb->enable_gpio = data->enable_gpio;
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pb->gpio_invert = data->gpio_invert;
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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->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_alloc;
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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 / max);
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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_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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pwm_backlight_alt_brightness_table_parse_dt(&pdev->dev, pb);
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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_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_config(pb->pwm, 0, pb->period);
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pwm_disable(pb->pwm);
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pwm_backlight_gpio_set(pb, false);
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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_config(pb->pwm, 0, pb->period);
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pwm_disable(pb->pwm);
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pwm_backlight_gpio_set(pb, false);
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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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