/* * 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");