/* * 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> struct pwm_bl_data { struct pwm_device *pwm; unsigned int period; int (*notify)(int brightness); }; 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(brightness); if (brightness == 0) { pwm_config(pb->pwm, 0, pb->period); pwm_disable(pb->pwm); } else { pwm_config(pb->pwm, brightness * pb->period / max, pb->period); pwm_enable(pb->pwm); } return 0; } static int pwm_backlight_get_brightness(struct backlight_device *bl) { return bl->props.brightness; } static struct backlight_ops pwm_backlight_ops = { .update_status = pwm_backlight_update_status, .get_brightness = pwm_backlight_get_brightness, }; static int pwm_backlight_probe(struct platform_device *pdev) { 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->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"); bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb, &pwm_backlight_ops); if (IS_ERR(bl)) { dev_err(&pdev->dev, "failed to register backlight\n"); ret = PTR_ERR(bl); goto err_bl; } bl->props.max_brightness = data->max_brightness; 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); 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");