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- /*
- * linux/drivers/video/backlight/pwm_bl.c
- *
- * simple PWM based backlight control, board code has to setup
- * 1) pin configuration so PWM waveforms can output
- * 2) platform_data being correctly configured
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
- #include <linux/module.h>
- #include <linux/kernel.h>
- #include <linux/init.h>
- #include <linux/platform_device.h>
- #include <linux/fb.h>
- #include <linux/backlight.h>
- #include <linux/err.h>
- #include <linux/pwm.h>
- #include <linux/pwm_backlight.h>
- #include <linux/slab.h>
- struct pwm_bl_data {
- struct pwm_device *pwm;
- struct device *dev;
- unsigned int period;
- unsigned int lth_brightness;
- int (*notify)(struct device *,
- int brightness);
- int (*check_fb)(struct device *, struct fb_info *);
- };
- static int pwm_backlight_update_status(struct backlight_device *bl)
- {
- struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
- int brightness = bl->props.brightness;
- int max = bl->props.max_brightness;
- if (bl->props.power != FB_BLANK_UNBLANK)
- brightness = 0;
- if (bl->props.fb_blank != FB_BLANK_UNBLANK)
- brightness = 0;
- if (pb->notify)
- brightness = pb->notify(pb->dev, brightness);
- if (brightness == 0) {
- pwm_config(pb->pwm, 0, pb->period);
- pwm_disable(pb->pwm);
- } else {
- brightness = pb->lth_brightness +
- (brightness * (pb->period - pb->lth_brightness) / max);
- pwm_config(pb->pwm, brightness, pb->period);
- pwm_enable(pb->pwm);
- }
- return 0;
- }
- static int pwm_backlight_get_brightness(struct backlight_device *bl)
- {
- return bl->props.brightness;
- }
- static int pwm_backlight_check_fb(struct backlight_device *bl,
- struct fb_info *info)
- {
- struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
- return !pb->check_fb || pb->check_fb(pb->dev, info);
- }
- static const struct backlight_ops pwm_backlight_ops = {
- .update_status = pwm_backlight_update_status,
- .get_brightness = pwm_backlight_get_brightness,
- .check_fb = pwm_backlight_check_fb,
- };
- static int pwm_backlight_probe(struct platform_device *pdev)
- {
- struct backlight_properties props;
- struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
- struct backlight_device *bl;
- struct pwm_bl_data *pb;
- int ret;
- if (!data) {
- dev_err(&pdev->dev, "failed to find platform data\n");
- return -EINVAL;
- }
- if (data->init) {
- ret = data->init(&pdev->dev);
- if (ret < 0)
- return ret;
- }
- pb = kzalloc(sizeof(*pb), GFP_KERNEL);
- if (!pb) {
- dev_err(&pdev->dev, "no memory for state\n");
- ret = -ENOMEM;
- goto err_alloc;
- }
- pb->period = data->pwm_period_ns;
- pb->notify = data->notify;
- pb->check_fb = data->check_fb;
- pb->lth_brightness = data->lth_brightness *
- (data->pwm_period_ns / data->max_brightness);
- pb->dev = &pdev->dev;
- pb->pwm = pwm_request(data->pwm_id, "backlight");
- if (IS_ERR(pb->pwm)) {
- dev_err(&pdev->dev, "unable to request PWM for backlight\n");
- ret = PTR_ERR(pb->pwm);
- goto err_pwm;
- } else
- dev_dbg(&pdev->dev, "got pwm for backlight\n");
- memset(&props, 0, sizeof(struct backlight_properties));
- props.type = BACKLIGHT_RAW;
- props.max_brightness = data->max_brightness;
- bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
- &pwm_backlight_ops, &props);
- if (IS_ERR(bl)) {
- dev_err(&pdev->dev, "failed to register backlight\n");
- ret = PTR_ERR(bl);
- goto err_bl;
- }
- bl->props.brightness = data->dft_brightness;
- backlight_update_status(bl);
- platform_set_drvdata(pdev, bl);
- return 0;
- err_bl:
- pwm_free(pb->pwm);
- err_pwm:
- kfree(pb);
- err_alloc:
- if (data->exit)
- data->exit(&pdev->dev);
- return ret;
- }
- static int pwm_backlight_remove(struct platform_device *pdev)
- {
- struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
- struct backlight_device *bl = platform_get_drvdata(pdev);
- struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
- backlight_device_unregister(bl);
- pwm_config(pb->pwm, 0, pb->period);
- pwm_disable(pb->pwm);
- pwm_free(pb->pwm);
- kfree(pb);
- if (data->exit)
- data->exit(&pdev->dev);
- return 0;
- }
- #ifdef CONFIG_PM
- static int pwm_backlight_suspend(struct platform_device *pdev,
- pm_message_t state)
- {
- struct backlight_device *bl = platform_get_drvdata(pdev);
- struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
- if (pb->notify)
- pb->notify(pb->dev, 0);
- pwm_config(pb->pwm, 0, pb->period);
- pwm_disable(pb->pwm);
- return 0;
- }
- static int pwm_backlight_resume(struct platform_device *pdev)
- {
- struct backlight_device *bl = platform_get_drvdata(pdev);
- backlight_update_status(bl);
- return 0;
- }
- #else
- #define pwm_backlight_suspend NULL
- #define pwm_backlight_resume NULL
- #endif
- static struct platform_driver pwm_backlight_driver = {
- .driver = {
- .name = "pwm-backlight",
- .owner = THIS_MODULE,
- },
- .probe = pwm_backlight_probe,
- .remove = pwm_backlight_remove,
- .suspend = pwm_backlight_suspend,
- .resume = pwm_backlight_resume,
- };
- static int __init pwm_backlight_init(void)
- {
- return platform_driver_register(&pwm_backlight_driver);
- }
- module_init(pwm_backlight_init);
- static void __exit pwm_backlight_exit(void)
- {
- platform_driver_unregister(&pwm_backlight_driver);
- }
- module_exit(pwm_backlight_exit);
- MODULE_DESCRIPTION("PWM based Backlight Driver");
- MODULE_LICENSE("GPL");
- MODULE_ALIAS("platform:pwm-backlight");
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