Commit c8df7428 authored by Christian Gmeiner's avatar Christian Gmeiner Committed by Linus Torvalds
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backlight: add driver for Bachmann's ot200 



Add backlight driver for Bachmann's ot200 visualisation device.  The
driver uses MFGPT 7 of CS5535 silicon to regulate the backlight.

[akpm@linux-foundation.org: remove redundant test of `brightness']
Signed-off-by: default avatarChristian Gmeiner <christian.gmeiner@gmail.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Andres Salomon <dilinger@queued.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7be865ab

drivers/video/backlight/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -341,6 +341,13 @@ config BACKLIGHT_LP855X 
	  This supports TI LP8550, LP8551, LP8552, LP8553 and LP8556

	  backlight driver.



config BACKLIGHT_OT200

	tristate "Backlight driver for ot200 visualisation device"

	depends on BACKLIGHT_CLASS_DEVICE && CS5535_MFGPT

	help

	  To compile this driver as a module, choose M here: the module will be

	  called ot200_bl.



endif # BACKLIGHT_CLASS_DEVICE



endif # BACKLIGHT_LCD_SUPPORT

drivers/video/backlight/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -39,4 +39,4 @@ obj-$(CONFIG_BACKLIGHT_ADP8870) += adp8870_bl.o 
obj-$(CONFIG_BACKLIGHT_88PM860X) += 88pm860x_bl.o

obj-$(CONFIG_BACKLIGHT_PCF50633)	+= pcf50633-backlight.o

obj-$(CONFIG_BACKLIGHT_AAT2870) += aat2870_bl.o

obj-$(CONFIG_BACKLIGHT_OT200) += ot200_bl.o

drivers/video/backlight/ot200_bl.c

0 → 100644
+175 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2012 Bachmann electronic GmbH

 *	Christian Gmeiner <christian.gmeiner@gmail.com>

 *

 * Backlight driver for ot200 visualisation device from

 * Bachmann electronic GmbH.

 *

 * 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/fb.h>

#include <linux/backlight.h>

#include <linux/gpio.h>

#include <linux/cs5535.h>



static struct cs5535_mfgpt_timer *pwm_timer;



/* this array defines the mapping of brightness in % to pwm frequency */

static const u8 dim_table[101] = {0, 0, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2,

				  2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4,

				  4, 5, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 9, 9,

				  10, 10, 11, 11, 12, 12, 13, 14, 15, 15, 16,

				  17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28,

				  30, 31, 33, 35, 37, 39, 41, 43, 45, 47, 50,

				  53, 55, 58, 61, 65, 68, 72, 75, 79, 84, 88,

				  93, 97, 103, 108, 114, 120, 126, 133, 140,

				  147, 155, 163};



struct ot200_backlight_data {

	int current_brightness;

};



#define GPIO_DIMM	27

#define SCALE		1

#define CMP1MODE	0x2	/* compare on GE; output high on compare

				 * greater than or equal */

#define PWM_SETUP	(SCALE | CMP1MODE << 6 | MFGPT_SETUP_CNTEN)

#define MAX_COMP2	163



static int ot200_backlight_update_status(struct backlight_device *bl)

{

	struct ot200_backlight_data *data = bl_get_data(bl);

	int brightness = bl->props.brightness;



	if (bl->props.state & BL_CORE_FBBLANK)

		brightness = 0;



	/* enable or disable PWM timer */

	if (brightness == 0)

		cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, 0);

	else if (data->current_brightness == 0) {

		cs5535_mfgpt_write(pwm_timer, MFGPT_REG_COUNTER, 0);

		cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP,

			MFGPT_SETUP_CNTEN);

	}



	/* apply new brightness value */

	cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1,

		MAX_COMP2 - dim_table[brightness]);

	data->current_brightness = brightness;



	return 0;

}



static int ot200_backlight_get_brightness(struct backlight_device *bl)

{

	struct ot200_backlight_data *data = bl_get_data(bl);

	return data->current_brightness;

}



static const struct backlight_ops ot200_backlight_ops = {

	.update_status	= ot200_backlight_update_status,

	.get_brightness	= ot200_backlight_get_brightness,

};



static int ot200_backlight_probe(struct platform_device *pdev)

{

	struct backlight_device *bl;

	struct ot200_backlight_data *data;

	struct backlight_properties props;

	int retval = 0;



	/* request gpio */

	if (gpio_request(GPIO_DIMM, "ot200 backlight dimmer") < 0) {

		dev_err(&pdev->dev, "failed to request GPIO %d\n", GPIO_DIMM);

		return -ENODEV;

	}



	/* request timer */

	pwm_timer = cs5535_mfgpt_alloc_timer(7, MFGPT_DOMAIN_ANY);

	if (!pwm_timer) {

		dev_err(&pdev->dev, "MFGPT 7 not available\n");

		retval = -ENODEV;

		goto error_mfgpt_alloc;

	}



	data = kzalloc(sizeof(*data), GFP_KERNEL);

	if (!data) {

		retval = -ENOMEM;

		goto error_kzalloc;

	}



	/* setup gpio */

	cs5535_gpio_set(GPIO_DIMM, GPIO_OUTPUT_ENABLE);

	cs5535_gpio_set(GPIO_DIMM, GPIO_OUTPUT_AUX1);



	/* setup timer */

	cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1, 0);

	cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP2, MAX_COMP2);

	cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, PWM_SETUP);



	data->current_brightness = 100;

	props.max_brightness = 100;

	props.brightness = 100;

	props.type = BACKLIGHT_RAW;



	bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, data,

					&ot200_backlight_ops, &props);

	if (IS_ERR(bl)) {

		dev_err(&pdev->dev, "failed to register backlight\n");

		retval = PTR_ERR(bl);

		goto error_backlight_device_register;

	}



	platform_set_drvdata(pdev, bl);



	return 0;



error_backlight_device_register:

	kfree(data);

error_kzalloc:

	cs5535_mfgpt_free_timer(pwm_timer);

error_mfgpt_alloc:

	gpio_free(GPIO_DIMM);

	return retval;

}



static int ot200_backlight_remove(struct platform_device *pdev)

{

	struct backlight_device *bl = platform_get_drvdata(pdev);

	struct ot200_backlight_data *data = bl_get_data(bl);



	backlight_device_unregister(bl);



	/* on module unload set brightness to 100% */

	cs5535_mfgpt_write(pwm_timer, MFGPT_REG_COUNTER, 0);

	cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);

	cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1,

		MAX_COMP2 - dim_table[100]);



	cs5535_mfgpt_free_timer(pwm_timer);

	gpio_free(GPIO_DIMM);



	kfree(data);

	return 0;

}



static struct platform_driver ot200_backlight_driver = {

	.driver		= {

		.name	= "ot200-backlight",

		.owner	= THIS_MODULE,

	},

	.probe		= ot200_backlight_probe,

	.remove		= ot200_backlight_remove,

};



module_platform_driver(ot200_backlight_driver);



MODULE_DESCRIPTION("backlight driver for ot200 visualisation device");

MODULE_AUTHOR("Christian Gmeiner <christian.gmeiner@gmail.com>");

MODULE_LICENSE("GPL");

MODULE_ALIAS("platform:ot200-backlight");

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