--- /dev/null
+/*
+ * Backlight driver for TWL4030 PWM0 -> TPS61161 combo.
+ * Based on pwm_bl.c
+ *
+ * Author: GraÅžvydas Ignotas <notasas@gmail.com>
+ *
+ * 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/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/fb.h>
+#include <linux/backlight.h>
+#include <linux/i2c/twl.h>
+#include <linux/err.h>
+
+#define TWL_PWM0_ON 0x00
+#define TWL_PWM0_OFF 0x01
+
+#define TWL_INTBR_GPBR1 0x0c
+#define TWL_INTBR_PMBR1 0x0d
+
+#define PWM0_CLK_ENABLE 1
+#define PWM0_ENABLE 4
+
+/* range accepted by hardware */
+#define MIN_VALUE 9
+#define MAX_VALUE 63
+#define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
+
+static int old_brightness;
+
+static void pwm0_disable(void)
+{
+ u8 r;
+
+ /* first disable PWM0 output, then clock */
+ twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
+ r &= ~PWM0_ENABLE;
+ twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
+ r &= ~PWM0_CLK_ENABLE;
+ twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
+}
+
+static int pwm0_backlight_update_status(struct backlight_device *bl)
+{
+ int brightness = bl->props.brightness;
+ u8 r;
+
+ if (bl->props.power != FB_BLANK_UNBLANK)
+ brightness = 0;
+
+ /* ignore fb blank for now
+ if (bl->props.fb_blank != FB_BLANK_UNBLANK)
+ brightness = 0;
+ */
+
+ if ((unsigned int)brightness > MAX_USER_VALUE)
+ brightness = MAX_USER_VALUE;
+
+ if (brightness == 0) {
+ if (old_brightness != 0)
+ pwm0_disable();
+
+ goto done;
+ }
+
+ if (old_brightness == 0) {
+ /* set PWM duty cycle to max. TPS61161 seems to use this
+ * to calibrate it's PWM sensitivity when it starts. */
+ twl_i2c_write_u8(TWL4030_MODULE_PWM0, MAX_VALUE,
+ TWL_PWM0_OFF);
+
+ /* first enable clock, then PWM0 out */
+ twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
+ r &= ~PWM0_ENABLE;
+ r |= PWM0_CLK_ENABLE;
+ twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
+ r |= PWM0_ENABLE;
+ twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
+
+ /* TI made it very easy to enable digital control, so easy that
+ * it often triggers unintentionally and disabes PWM control,
+ * so wait until 1 wire mode detection window ends. */
+ udelay(2000);
+ }
+
+ twl_i2c_write_u8(TWL4030_MODULE_PWM0, MIN_VALUE + brightness,
+ TWL_PWM0_OFF);
+
+done:
+ old_brightness = brightness;
+ return 0;
+}
+
+static int pwm0_backlight_get_brightness(struct backlight_device *bl)
+{
+ return bl->props.brightness;
+}
+
+static const struct backlight_ops pwm0_backlight_ops = {
+ .update_status = pwm0_backlight_update_status,
+ .get_brightness = pwm0_backlight_get_brightness,
+};
+
+static int pwm0_backlight_probe(struct platform_device *pdev)
+{
+ struct backlight_properties props;
+ struct backlight_device *bl;
+ u8 r;
+
+ memset(&props, 0, sizeof(props));
+ props.max_brightness = MAX_USER_VALUE;
+ bl = backlight_device_register(pdev->name, &pdev->dev,
+ NULL, &pwm0_backlight_ops, &props);
+ if (IS_ERR(bl)) {
+ dev_err(&pdev->dev, "failed to register backlight\n");
+ return PTR_ERR(bl);
+ }
+
+ /* 64 cycle period, ON position 0 */
+ twl_i2c_write_u8(TWL4030_MODULE_PWM0, 0x80, TWL_PWM0_ON);
+
+ bl->props.brightness = MAX_USER_VALUE;
+ backlight_update_status(bl);
+
+ /* enable PWM function in pin mux (i2c addr 0x49 0x92) */
+ twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
+ r &= ~0x0c;
+ r |= 0x04;
+ twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
+
+ return 0;
+}
+
+static int pwm0_backlight_remove(struct platform_device *pdev)
+{
+ struct backlight_device *bl = platform_get_drvdata(pdev);
+ backlight_device_unregister(bl);
+ return 0;
+}
+
+#ifdef CONFIG_PM
+static int pwm0_backlight_suspend(struct platform_device *pdev,
+ pm_message_t state)
+{
+ pwm0_disable();
+ old_brightness = 0;
+
+ return 0;
+}
+
+static int pwm0_backlight_resume(struct platform_device *pdev)
+{
+ struct backlight_device *bl = platform_get_drvdata(pdev);
+
+ backlight_update_status(bl);
+ return 0;
+}
+#else
+#define pwm0_backlight_suspend NULL
+#define pwm0_backlight_resume NULL
+#endif
+
+static struct platform_driver pwm0_backlight_driver = {
+ .driver = {
+ .name = "twl4030-pwm0-bl",
+ .owner = THIS_MODULE,
+ },
+ .probe = pwm0_backlight_probe,
+ .remove = pwm0_backlight_remove,
+ .suspend = pwm0_backlight_suspend,
+ .resume = pwm0_backlight_resume,
+};
+
+static int __init pwm0_backlight_init(void)
+{
+ return platform_driver_register(&pwm0_backlight_driver);
+}
+module_init(pwm0_backlight_init);
+
+static void __exit pwm0_backlight_exit(void)
+{
+ platform_driver_unregister(&pwm0_backlight_driver);
+}
+module_exit(pwm0_backlight_exit);
+
+MODULE_DESCRIPTION("TWL4030 PWM0 Backlight Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:twl4030-pwm0-bl");