/drivers/video/backlight/max8925_bl.c

  1/*
  2 * Backlight driver for Maxim MAX8925
  3 *
  4 * Copyright (C) 2009 Marvell International Ltd.
  5 *      Haojian Zhuang <haojian.zhuang@marvell.com>
  6 *
  7 * This program is free software; you can redistribute it and/or modify
  8 * it under the terms of the GNU General Public License version 2 as
  9 * published by the Free Software Foundation.
 10 */
 11
 12#include <linux/init.h>
 13#include <linux/kernel.h>
 14#include <linux/platform_device.h>
 15#include <linux/fb.h>
 16#include <linux/i2c.h>
 17#include <linux/backlight.h>
 18#include <linux/mfd/max8925.h>
 19#include <linux/slab.h>
 20
 21#define MAX_BRIGHTNESS		(0xff)
 22#define MIN_BRIGHTNESS		(0)
 23
 24#define LWX_FREQ(x)		(((x - 601) / 100) & 0x7)
 25
 26struct max8925_backlight_data {
 27	struct max8925_chip	*chip;
 28
 29	int		current_brightness;
 30};
 31
 32static int max8925_backlight_set(struct backlight_device *bl, int brightness)
 33{
 34	struct max8925_backlight_data *data = bl_get_data(bl);
 35	struct max8925_chip *chip = data->chip;
 36	unsigned char value;
 37	int ret;
 38
 39	if (brightness > MAX_BRIGHTNESS)
 40		value = MAX_BRIGHTNESS;
 41	else
 42		value = brightness;
 43
 44	ret = max8925_reg_write(chip->i2c, MAX8925_WLED_CNTL, value);
 45	if (ret < 0)
 46		goto out;
 47
 48	if (!data->current_brightness && brightness)
 49		/* enable WLED output */
 50		ret = max8925_set_bits(chip->i2c, MAX8925_WLED_MODE_CNTL, 1, 1);
 51	else if (!brightness)
 52		/* disable WLED output */
 53		ret = max8925_set_bits(chip->i2c, MAX8925_WLED_MODE_CNTL, 1, 0);
 54	if (ret < 0)
 55		goto out;
 56	dev_dbg(chip->dev, "set brightness %d\n", value);
 57	data->current_brightness = value;
 58	return 0;
 59out:
 60	dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n",
 61		value, ret);
 62	return ret;
 63}
 64
 65static int max8925_backlight_update_status(struct backlight_device *bl)
 66{
 67	int brightness = bl->props.brightness;
 68
 69	if (bl->props.power != FB_BLANK_UNBLANK)
 70		brightness = 0;
 71
 72	if (bl->props.fb_blank != FB_BLANK_UNBLANK)
 73		brightness = 0;
 74
 75	if (bl->props.state & BL_CORE_SUSPENDED)
 76		brightness = 0;
 77
 78	return max8925_backlight_set(bl, brightness);
 79}
 80
 81static int max8925_backlight_get_brightness(struct backlight_device *bl)
 82{
 83	struct max8925_backlight_data *data = bl_get_data(bl);
 84	struct max8925_chip *chip = data->chip;
 85	int ret;
 86
 87	ret = max8925_reg_read(chip->i2c, MAX8925_WLED_CNTL);
 88	if (ret < 0)
 89		return -EINVAL;
 90	data->current_brightness = ret;
 91	dev_dbg(chip->dev, "get brightness %d\n", data->current_brightness);
 92	return ret;
 93}
 94
 95static struct backlight_ops max8925_backlight_ops = {
 96	.options	= BL_CORE_SUSPENDRESUME,
 97	.update_status	= max8925_backlight_update_status,
 98	.get_brightness	= max8925_backlight_get_brightness,
 99};
100
101static int __devinit max8925_backlight_probe(struct platform_device *pdev)
102{
103	struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent);
104	struct max8925_platform_data *max8925_pdata;
105	struct max8925_backlight_pdata *pdata = NULL;
106	struct max8925_backlight_data *data;
107	struct backlight_device *bl;
108	struct backlight_properties props;
109	struct resource *res;
110	char name[MAX8925_NAME_SIZE];
111	unsigned char value;
112	int ret;
113
114	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
115	if (res == NULL) {
116		dev_err(&pdev->dev, "No I/O resource!\n");
117		return -EINVAL;
118	}
119
120	if (pdev->dev.parent->platform_data) {
121		max8925_pdata = pdev->dev.parent->platform_data;
122		pdata = max8925_pdata->backlight;
123	}
124
125	if (!pdata) {
126		dev_err(&pdev->dev, "platform data isn't assigned to "
127			"backlight\n");
128		return -EINVAL;
129	}
130
131	data = kzalloc(sizeof(struct max8925_backlight_data), GFP_KERNEL);
132	if (data == NULL)
133		return -ENOMEM;
134	strncpy(name, res->name, MAX8925_NAME_SIZE);
135	data->chip = chip;
136	data->current_brightness = 0;
137
138	memset(&props, 0, sizeof(struct backlight_properties));
139	props.max_brightness = MAX_BRIGHTNESS;
140	bl = backlight_device_register(name, &pdev->dev, data,
141					&max8925_backlight_ops, &props);
142	if (IS_ERR(bl)) {
143		dev_err(&pdev->dev, "failed to register backlight\n");
144		kfree(data);
145		return PTR_ERR(bl);
146	}
147	bl->props.brightness = MAX_BRIGHTNESS;
148
149	platform_set_drvdata(pdev, bl);
150
151	value = 0;
152	if (pdata->lxw_scl)
153		value |= (1 << 7);
154	if (pdata->lxw_freq)
155		value |= (LWX_FREQ(pdata->lxw_freq) << 4);
156	if (pdata->dual_string)
157		value |= (1 << 1);
158	ret = max8925_set_bits(chip->i2c, MAX8925_WLED_MODE_CNTL, 0xfe, value);
159	if (ret < 0)
160		goto out;
161
162	backlight_update_status(bl);
163	return 0;
164out:
165	kfree(data);
166	return ret;
167}
168
169static int __devexit max8925_backlight_remove(struct platform_device *pdev)
170{
171	struct backlight_device *bl = platform_get_drvdata(pdev);
172	struct max8925_backlight_data *data = bl_get_data(bl);
173
174	backlight_device_unregister(bl);
175	kfree(data);
176	return 0;
177}
178
179static struct platform_driver max8925_backlight_driver = {
180	.driver		= {
181		.name	= "max8925-backlight",
182		.owner	= THIS_MODULE,
183	},
184	.probe		= max8925_backlight_probe,
185	.remove		= __devexit_p(max8925_backlight_remove),
186};
187
188static int __init max8925_backlight_init(void)
189{
190	return platform_driver_register(&max8925_backlight_driver);
191}
192module_init(max8925_backlight_init);
193
194static void __exit max8925_backlight_exit(void)
195{
196	platform_driver_unregister(&max8925_backlight_driver);
197};
198module_exit(max8925_backlight_exit);
199
200MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925");
201MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
202MODULE_LICENSE("GPL");
203MODULE_ALIAS("platform:max8925-backlight");