| /* |
| * 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> |
| #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 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 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; |
| int retval; |
| |
| pwmbl = devm_kzalloc(&pdev->dev, 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 = devm_gpio_request(&pdev->dev, pwmbl->gpio_on, |
| "gpio_atmel_pwm_bl"); |
| if (retval) { |
| pwmbl->gpio_on = -1; |
| goto err_free_pwm; |
| } |
| |
| /* Turn display off by default. */ |
| retval = gpio_direction_output(pwmbl->gpio_on, |
| 0 ^ pdata->on_active_low); |
| 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 = backlight_device_register("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_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_pwm: |
| pwm_channel_free(&pwmbl->pwmc); |
| err_free_mem: |
| 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); |
| pwm_channel_disable(&pwmbl->pwmc); |
| pwm_channel_free(&pwmbl->pwmc); |
| backlight_device_unregister(pwmbl->bldev); |
| platform_set_drvdata(pdev, NULL); |
| |
| 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"); |