diff options
Diffstat (limited to 'drivers/video/backlight/pwm_bl.c')
| -rw-r--r-- | drivers/video/backlight/pwm_bl.c | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c new file mode 100644 index 00000000000..6338d0e2fe0 --- /dev/null +++ b/drivers/video/backlight/pwm_bl.c @@ -0,0 +1,185 @@ +/* + * 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 casts to the PWM id (0/1/2/3 on PXA) + * + * 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) + return -EINVAL; + + if (data->init) { + ret = data->init(&pdev->dev); + if (ret < 0) + return ret; + } + + pb = kzalloc(sizeof(*pb), GFP_KERNEL); + if (!pb) { + 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; + } + + bl = backlight_device_register(pdev->name, &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"); |