Commit 35c1682c authored by Grazvydas Ignotas's avatar Grazvydas Ignotas Committed by Linus Torvalds
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backlight: add support for Pandora backlight 



Add support for pandora (openpandora.org) backlight.

It might look like all this could be done using pwm_bl.c instead, but
there is a need of special programming sequence when turning on the LED
driver chip or else it will misbehave.  Doing this using pwm_bl.c would
require to use some register programming and pwm functions from platform
code, and ARM maintainers are allergic to driver-like code in /arch/arm
nowadays.  The PMIC PWM driver is currently missing too, so pwm_bl.c
can't be used anyway.

Signed-off-by: default avatarGrazvydas Ignotas <notasas@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c8df7428

drivers/video/backlight/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -348,6 +348,13 @@ config BACKLIGHT_OT200 
	  To compile this driver as a module, choose M here: the module will be

	  called ot200_bl.



config BACKLIGHT_PANDORA

	tristate "Backlight driver for Pandora console"

	depends on TWL4030_CORE

	help

	  If you have a Pandora console, say Y to enable the

	  backlight driver.



endif # BACKLIGHT_CLASS_DEVICE



endif # BACKLIGHT_LCD_SUPPORT

drivers/video/backlight/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ obj-$(CONFIG_BACKLIGHT_HP680) += hp680_bl.o 
obj-$(CONFIG_BACKLIGHT_LOCOMO)	+= locomolcd.o

obj-$(CONFIG_BACKLIGHT_LP855X)	+= lp855x_bl.o

obj-$(CONFIG_BACKLIGHT_OMAP1)	+= omap1_bl.o

obj-$(CONFIG_BACKLIGHT_PANDORA)	+= pandora_bl.o

obj-$(CONFIG_BACKLIGHT_PROGEAR) += progear_bl.o

obj-$(CONFIG_BACKLIGHT_CARILLO_RANCH) += cr_bllcd.o

obj-$(CONFIG_BACKLIGHT_PWM)	+= pwm_bl.o

drivers/video/backlight/pandora_bl.c

0 → 100644
+171 −0
Original line number Diff line number Diff line 
/*

 * 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(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.

		 */

		usleep_range(2000, 10000);

	}



	twl_i2c_write_u8(TWL4030_MODULE_PWM0, 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 int pandora_backlight_get_brightness(struct backlight_device *bl)

{

	return bl->props.brightness;

}



static const struct backlight_ops pandora_backlight_ops = {

	.options	= BL_CORE_SUSPENDRESUME,

	.update_status	= pandora_backlight_update_status,

	.get_brightness	= pandora_backlight_get_brightness,

};



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 = backlight_device_register(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(TWL4030_MODULE_PWM0, 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 int pandora_backlight_remove(struct platform_device *pdev)

{

	struct backlight_device *bl = platform_get_drvdata(pdev);

	backlight_device_unregister(bl);

	return 0;

}



static struct platform_driver pandora_backlight_driver = {

	.driver		= {

		.name	= "pandora-backlight",

		.owner	= THIS_MODULE,

	},

	.probe		= pandora_backlight_probe,

	.remove		= pandora_backlight_remove,

};



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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