diff options
Diffstat (limited to 'drivers/video/backlight/atmel-pwm-bl.c')
| -rw-r--r-- | drivers/video/backlight/atmel-pwm-bl.c | 223 |
1 files changed, 223 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..261b1a4ec3d --- /dev/null +++ b/drivers/video/backlight/atmel-pwm-bl.c @@ -0,0 +1,223 @@ +/* + * 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/gpio.h> +#include <linux/backlight.h> +#include <linux/atmel_pwm.h> +#include <linux/atmel-pwm-bl.h> +#include <linux/slab.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 void atmel_pwm_bl_set_gpio_on(struct atmel_pwm_bl *pwmbl, int on) +{ + if (!gpio_is_valid(pwmbl->gpio_on)) + return; + + gpio_set_value(pwmbl->gpio_on, on ^ pwmbl->pdata->on_active_low); +} + +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) { + atmel_pwm_bl_set_gpio_on(pwmbl, 0); + 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); + atmel_pwm_bl_set_gpio_on(pwmbl, 1); + } + + return 0; +} + +static int atmel_pwm_bl_get_intensity(struct backlight_device *bd) +{ + struct atmel_pwm_bl *pwmbl = bl_get_data(bd); + u32 cdty; + u32 intensity; + + cdty = pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY); + if (pwmbl->pdata->pwm_active_low) + intensity = cdty - pwmbl->pdata->pwm_duty_min; + else + intensity = pwmbl->pdata->pwm_duty_max - cdty; + + return intensity & 0xffff; +} + +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 const 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) +{ + struct backlight_properties props; + const struct atmel_pwm_bl_platform_data *pdata; + struct backlight_device *bldev; + struct atmel_pwm_bl *pwmbl; + unsigned long flags; + int retval; + + pdata = dev_get_platdata(&pdev->dev); + if (!pdata) + return -ENODEV; + + if (pdata->pwm_compare_max < pdata->pwm_duty_max || + pdata->pwm_duty_min > pdata->pwm_duty_max || + pdata->pwm_frequency == 0) + return -EINVAL; + + pwmbl = devm_kzalloc(&pdev->dev, sizeof(struct atmel_pwm_bl), + GFP_KERNEL); + if (!pwmbl) + return -ENOMEM; + + pwmbl->pdev = pdev; + pwmbl->pdata = pdata; + pwmbl->gpio_on = pdata->gpio_on; + + retval = pwm_channel_alloc(pdata->pwm_channel, &pwmbl->pwmc); + if (retval) + return retval; + + if (gpio_is_valid(pwmbl->gpio_on)) { + /* Turn display off by default. */ + if (pdata->on_active_low) + flags = GPIOF_OUT_INIT_HIGH; + else + flags = GPIOF_OUT_INIT_LOW; + + retval = devm_gpio_request_one(&pdev->dev, pwmbl->gpio_on, + flags, "gpio_atmel_pwm_bl"); + if (retval) + goto err_free_pwm; + } + + memset(&props, 0, sizeof(struct backlight_properties)); + props.type = BACKLIGHT_RAW; + props.max_brightness = pdata->pwm_duty_max - pdata->pwm_duty_min; + bldev = devm_backlight_device_register(&pdev->dev, "atmel-pwm-bl", + &pdev->dev, pwmbl, &atmel_pwm_bl_ops, + &props); + if (IS_ERR(bldev)) { + retval = PTR_ERR(bldev); + goto err_free_pwm; + } + + 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.brightness = bldev->props.max_brightness / 2; + + retval = atmel_pwm_bl_init_pwm(pwmbl); + if (retval) + goto err_free_pwm; + + atmel_pwm_bl_set_intensity(bldev); + + return 0; + +err_free_pwm: + pwm_channel_free(&pwmbl->pwmc); + + return retval; +} + +static int atmel_pwm_bl_remove(struct platform_device *pdev) +{ + struct atmel_pwm_bl *pwmbl = platform_get_drvdata(pdev); + + atmel_pwm_bl_set_gpio_on(pwmbl, 0); + pwm_channel_disable(&pwmbl->pwmc); + pwm_channel_free(&pwmbl->pwmc); + + return 0; +} + +static struct platform_driver atmel_pwm_bl_driver = { + .driver = { + .name = "atmel-pwm-bl", + }, + /* REVISIT add suspend() and resume() */ + .probe = atmel_pwm_bl_probe, + .remove = atmel_pwm_bl_remove, +}; + +module_platform_driver(atmel_pwm_bl_driver); + +MODULE_AUTHOR("Hans-Christian egtvedt <hans-christian.egtvedt@atmel.com>"); +MODULE_DESCRIPTION("Atmel PWM backlight driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:atmel-pwm-bl"); |