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/*
* Backlight driver for Pandora handheld.
* Pandora uses TWL4030 PWM0 -> TPS61161 combo for control backlight.
* Based on pwm_bl.c
*
* Copyright 2009,2012 Gražvydas 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 TWL_PMBR1_PWM0_MUXMASK 0x0c
#define TWL_PMBR1_PWM0 0x04
#define PWM0_CLK_ENABLE BIT(0)
#define PWM0_ENABLE BIT(2)
/* range accepted by hardware */
#define MIN_VALUE 9
#define MAX_VALUE 63
#define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
#define PANDORABL_WAS_OFF BL_CORE_DRIVER1
static int pandora_backlight_update_status(struct backlight_device *bl)
{
int brightness = bl->props.brightness;
u8 r;
if (bl->props.power != FB_BLANK_UNBLANK)
brightness = 0;
if (bl->props.state & BL_CORE_FBBLANK)
brightness = 0;
if (bl->props.state & BL_CORE_SUSPENDED)
brightness = 0;
if ((unsigned int)brightness > MAX_USER_VALUE)
brightness = MAX_USER_VALUE;
if (brightness == 0) {
if (bl->props.state & PANDORABL_WAS_OFF)
goto done;
/* 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);
goto done;
}
if (bl->props.state & PANDORABL_WAS_OFF) {
/*
* set PWM duty cycle to max. TPS61161 seems to use this
* to calibrate it's PWM sensitivity when it starts.
*/
twl_i2c_write_u8(TWL_MODULE_PWM, 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.
*/
usleep_range(2000, 10000);
}
twl_i2c_write_u8(TWL_MODULE_PWM, MIN_VALUE + brightness, TWL_PWM0_OFF);
done:
if (brightness != 0)
bl->props.state &= ~PANDORABL_WAS_OFF;
else
bl->props.state |= PANDORABL_WAS_OFF;
return 0;
}
static const struct backlight_ops pandora_backlight_ops = {
.options = BL_CORE_SUSPENDRESUME,
.update_status = pandora_backlight_update_status,
};
static int pandora_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;
props.type = BACKLIGHT_RAW;
bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev,
NULL, &pandora_backlight_ops, &props);
if (IS_ERR(bl)) {
dev_err(&pdev->dev, "failed to register backlight\n");
return PTR_ERR(bl);
}
platform_set_drvdata(pdev, bl);
/* 64 cycle period, ON position 0 */
twl_i2c_write_u8(TWL_MODULE_PWM, 0x80, TWL_PWM0_ON);
bl->props.state |= PANDORABL_WAS_OFF;
bl->props.brightness = MAX_USER_VALUE;
backlight_update_status(bl);
/* enable PWM function in pin mux */
twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
r &= ~TWL_PMBR1_PWM0_MUXMASK;
r |= TWL_PMBR1_PWM0;
twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
return 0;
}
static struct platform_driver pandora_backlight_driver = {
.driver = {
.name = "pandora-backlight",
.owner = THIS_MODULE,
},
.probe = pandora_backlight_probe,
};
module_platform_driver(pandora_backlight_driver);
MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>");
MODULE_DESCRIPTION("Pandora Backlight Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:pandora-backlight");
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