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path: root/drivers/video/backlight/atmel-pwm-bl.c
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Diffstat (limited to 'drivers/video/backlight/atmel-pwm-bl.c')
-rw-r--r--drivers/video/backlight/atmel-pwm-bl.c244
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");
generated by cgit v1.2.3-70-g09d2 (git 2.51.2) at 2025-11-04 02:49:00 +0000