diff options
Diffstat (limited to 'drivers/video/backlight/atmel-pwm-bl.c')
| -rw-r--r-- | drivers/video/backlight/atmel-pwm-bl.c | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/drivers/video/backlight/atmel-pwm-bl.c b/drivers/video/backlight/atmel-pwm-bl.c new file mode 100644 index 00000000000..505c0823a10 --- /dev/null +++ b/drivers/video/backlight/atmel-pwm-bl.c @@ -0,0 +1,244 @@ +/* + * Copyright (C) 2008 Atmel Corporation + * + * Backlight driver using Atmel PWM peripheral. + * + * 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/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/fb.h> +#include <linux/clk.h> +#include <linux/gpio.h> +#include <linux/backlight.h> +#include <linux/atmel_pwm.h> +#include <linux/atmel-pwm-bl.h> + +struct atmel_pwm_bl { + const struct atmel_pwm_bl_platform_data *pdata; + struct backlight_device *bldev; + struct platform_device *pdev; + struct pwm_channel pwmc; + int gpio_on; +}; + +static int atmel_pwm_bl_set_intensity(struct backlight_device *bd) +{ + struct atmel_pwm_bl *pwmbl = bl_get_data(bd); + int intensity = bd->props.brightness; + int pwm_duty; + + if (bd->props.power != FB_BLANK_UNBLANK) + intensity = 0; + if (bd->props.fb_blank != FB_BLANK_UNBLANK) + intensity = 0; + + if (pwmbl->pdata->pwm_active_low) + pwm_duty = pwmbl->pdata->pwm_duty_min + intensity; + else + pwm_duty = pwmbl->pdata->pwm_duty_max - intensity; + + if (pwm_duty > pwmbl->pdata->pwm_duty_max) + pwm_duty = pwmbl->pdata->pwm_duty_max; + if (pwm_duty < pwmbl->pdata->pwm_duty_min) + pwm_duty = pwmbl->pdata->pwm_duty_min; + + if (!intensity) { + if (pwmbl->gpio_on != -1) { + gpio_set_value(pwmbl->gpio_on, + 0 ^ pwmbl->pdata->on_active_low); + } + pwm_channel_writel(&pwmbl->pwmc, PWM_CUPD, pwm_duty); + pwm_channel_disable(&pwmbl->pwmc); + } else { + pwm_channel_enable(&pwmbl->pwmc); + pwm_channel_writel(&pwmbl->pwmc, PWM_CUPD, pwm_duty); + if (pwmbl->gpio_on != -1) { + gpio_set_value(pwmbl->gpio_on, + 1 ^ pwmbl->pdata->on_active_low); + } + } + + return 0; +} + +static int atmel_pwm_bl_get_intensity(struct backlight_device *bd) +{ + struct atmel_pwm_bl *pwmbl = bl_get_data(bd); + u8 intensity; + + if (pwmbl->pdata->pwm_active_low) { + intensity = pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY) - + pwmbl->pdata->pwm_duty_min; + } else { + intensity = pwmbl->pdata->pwm_duty_max - + pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY); + } + + return intensity; +} + +static int atmel_pwm_bl_init_pwm(struct atmel_pwm_bl *pwmbl) +{ + unsigned long pwm_rate = pwmbl->pwmc.mck; + unsigned long prescale = DIV_ROUND_UP(pwm_rate, + (pwmbl->pdata->pwm_frequency * + pwmbl->pdata->pwm_compare_max)) - 1; + + /* + * Prescale must be power of two and maximum 0xf in size because of + * hardware limit. PWM speed will be: + * PWM module clock speed / (2 ^ prescale). + */ + prescale = fls(prescale); + if (prescale > 0xf) + prescale = 0xf; + + pwm_channel_writel(&pwmbl->pwmc, PWM_CMR, prescale); + pwm_channel_writel(&pwmbl->pwmc, PWM_CDTY, + pwmbl->pdata->pwm_duty_min + + pwmbl->bldev->props.brightness); + pwm_channel_writel(&pwmbl->pwmc, PWM_CPRD, + pwmbl->pdata->pwm_compare_max); + + dev_info(&pwmbl->pdev->dev, "Atmel PWM backlight driver " + "(%lu Hz)\n", pwmbl->pwmc.mck / + pwmbl->pdata->pwm_compare_max / + (1 << prescale)); + + return pwm_channel_enable(&pwmbl->pwmc); +} + +static struct backlight_ops atmel_pwm_bl_ops = { + .get_brightness = atmel_pwm_bl_get_intensity, + .update_status = atmel_pwm_bl_set_intensity, +}; + +static int atmel_pwm_bl_probe(struct platform_device *pdev) +{ + const struct atmel_pwm_bl_platform_data *pdata; + struct backlight_device *bldev; + struct atmel_pwm_bl *pwmbl; + int retval; + + pwmbl = kzalloc(sizeof(struct atmel_pwm_bl), GFP_KERNEL); + if (!pwmbl) + return -ENOMEM; + + pwmbl->pdev = pdev; + + pdata = pdev->dev.platform_data; + if (!pdata) { + retval = -ENODEV; + goto err_free_mem; + } + + if (pdata->pwm_compare_max < pdata->pwm_duty_max || + pdata->pwm_duty_min > pdata->pwm_duty_max || + pdata->pwm_frequency == 0) { + retval = -EINVAL; + goto err_free_mem; + } + + pwmbl->pdata = pdata; + pwmbl->gpio_on = pdata->gpio_on; + + retval = pwm_channel_alloc(pdata->pwm_channel, &pwmbl->pwmc); + if (retval) + goto err_free_mem; + + if (pwmbl->gpio_on != -1) { + retval = gpio_request(pwmbl->gpio_on, "gpio_atmel_pwm_bl"); + if (retval) { + pwmbl->gpio_on = -1; + goto err_free_pwm; + } + + /* Turn display off by defatult. */ + retval = gpio_direction_output(pwmbl->gpio_on, + 0 ^ pdata->on_active_low); + if (retval) + goto err_free_gpio; + } + + bldev = backlight_device_register("atmel-pwm-bl", + &pdev->dev, pwmbl, &atmel_pwm_bl_ops); + if (IS_ERR(bldev)) { + retval = PTR_ERR(bldev); + goto err_free_gpio; + } + + pwmbl->bldev = bldev; + + platform_set_drvdata(pdev, pwmbl); + + /* Power up the backlight by default at middle intesity. */ + bldev->props.power = FB_BLANK_UNBLANK; + bldev->props.max_brightness = pdata->pwm_duty_max - pdata->pwm_duty_min; + bldev->props.brightness = bldev->props.max_brightness / 2; + + retval = atmel_pwm_bl_init_pwm(pwmbl); + if (retval) + goto err_free_bl_dev; + + atmel_pwm_bl_set_intensity(bldev); + + return 0; + +err_free_bl_dev: + platform_set_drvdata(pdev, NULL); + backlight_device_unregister(bldev); +err_free_gpio: + if (pwmbl->gpio_on != -1) + gpio_free(pwmbl->gpio_on); +err_free_pwm: + pwm_channel_free(&pwmbl->pwmc); +err_free_mem: + kfree(pwmbl); + return retval; +} + +static int __exit atmel_pwm_bl_remove(struct platform_device *pdev) +{ + struct atmel_pwm_bl *pwmbl = platform_get_drvdata(pdev); + + if (pwmbl->gpio_on != -1) { + gpio_set_value(pwmbl->gpio_on, 0); + gpio_free(pwmbl->gpio_on); + } + pwm_channel_disable(&pwmbl->pwmc); + pwm_channel_free(&pwmbl->pwmc); + backlight_device_unregister(pwmbl->bldev); + platform_set_drvdata(pdev, NULL); + kfree(pwmbl); + + return 0; +} + +static struct platform_driver atmel_pwm_bl_driver = { + .driver = { + .name = "atmel-pwm-bl", + }, + /* REVISIT add suspend() and resume() */ + .remove = __exit_p(atmel_pwm_bl_remove), +}; + +static int __init atmel_pwm_bl_init(void) +{ + return platform_driver_probe(&atmel_pwm_bl_driver, atmel_pwm_bl_probe); +} +module_init(atmel_pwm_bl_init); + +static void __exit atmel_pwm_bl_exit(void) +{ + platform_driver_unregister(&atmel_pwm_bl_driver); +} +module_exit(atmel_pwm_bl_exit); + +MODULE_AUTHOR("Hans-Christian egtvedt <hans-christian.egtvedt@atmel.com>"); +MODULE_DESCRIPTION("Atmel PWM backlight driver"); +MODULE_LICENSE("GPL"); |