pcf50633-backlight.c revision bb7ca747f8d6243b3943c5b133048652020f4a50 
1/*
2 *  Copyright (C) 2009-2010, Lars-Peter Clausen <lars@metafoo.de>
3 *      PCF50633 backlight device driver
4 *
5 *  This program is free software; you can redistribute	 it and/or modify it
6 *  under  the terms of	 the GNU General  Public License as published by the
7 *  Free Software Foundation;  either version 2 of the	License, or (at your
8 *  option) any later version.
9 *
10 *  You should have received a copy of the  GNU General Public License along
11 *  with this program; if not, write  to the Free Software Foundation, Inc.,
12 *  675 Mass Ave, Cambridge, MA 02139, USA.
13 *
14 */
15
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/slab.h>
19#include <linux/platform_device.h>
20
21#include <linux/backlight.h>
22#include <linux/fb.h>
23
24#include <linux/mfd/pcf50633/core.h>
25#include <linux/mfd/pcf50633/backlight.h>
26
27struct pcf50633_bl {
28	struct pcf50633 *pcf;
29	struct backlight_device *bl;
30
31	unsigned int brightness;
32	unsigned int brightness_limit;
33};
34
35/*
36 * pcf50633_bl_set_brightness_limit
37 *
38 * Update the brightness limit for the pc50633 backlight. The actual brightness
39 * will not go above the limit. This is useful to limit power drain for example
40 * on low battery.
41 *
42 * @dev: Pointer to a pcf50633 device
43 * @limit: The brightness limit. Valid values are 0-63
44 */
45int pcf50633_bl_set_brightness_limit(struct pcf50633 *pcf, unsigned int limit)
46{
47	struct pcf50633_bl *pcf_bl = platform_get_drvdata(pcf->bl_pdev);
48
49	if (!pcf_bl)
50		return -ENODEV;
51
52	pcf_bl->brightness_limit = limit & 0x3f;
53	backlight_update_status(pcf_bl->bl);
54
55    return 0;
56}
57
58static int pcf50633_bl_update_status(struct backlight_device *bl)
59{
60	struct pcf50633_bl *pcf_bl = bl_get_data(bl);
61	unsigned int new_brightness;
62
63
64	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK) ||
65		bl->props.power != FB_BLANK_UNBLANK)
66		new_brightness = 0;
67	else if (bl->props.brightness < pcf_bl->brightness_limit)
68		new_brightness = bl->props.brightness;
69	else
70		new_brightness = pcf_bl->brightness_limit;
71
72
73	if (pcf_bl->brightness == new_brightness)
74		return 0;
75
76	if (new_brightness) {
77		pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDOUT,
78					new_brightness);
79		if (!pcf_bl->brightness)
80			pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDENA, 1);
81	} else {
82		pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDENA, 0);
83	}
84
85	pcf_bl->brightness = new_brightness;
86
87	return 0;
88}
89
90static int pcf50633_bl_get_brightness(struct backlight_device *bl)
91{
92	struct pcf50633_bl *pcf_bl = bl_get_data(bl);
93	return pcf_bl->brightness;
94}
95
96static const struct backlight_ops pcf50633_bl_ops = {
97	.get_brightness = pcf50633_bl_get_brightness,
98	.update_status	= pcf50633_bl_update_status,
99	.options	= BL_CORE_SUSPENDRESUME,
100};
101
102static int __devinit pcf50633_bl_probe(struct platform_device *pdev)
103{
104	int ret;
105	struct pcf50633_bl *pcf_bl;
106	struct device *parent = pdev->dev.parent;
107	struct pcf50633_platform_data *pcf50633_data = parent->platform_data;
108	struct pcf50633_bl_platform_data *pdata = pcf50633_data->backlight_data;
109	struct backlight_properties bl_props;
110
111	pcf_bl = kzalloc(sizeof(*pcf_bl), GFP_KERNEL);
112	if (!pcf_bl)
113		return -ENOMEM;
114
115	bl_props.type = BACKLIGHT_RAW;
116	bl_props.max_brightness = 0x3f;
117	bl_props.power = FB_BLANK_UNBLANK;
118
119	if (pdata) {
120		bl_props.brightness = pdata->default_brightness;
121		pcf_bl->brightness_limit = pdata->default_brightness_limit;
122	} else {
123		bl_props.brightness = 0x3f;
124		pcf_bl->brightness_limit = 0x3f;
125	}
126
127	pcf_bl->pcf = dev_to_pcf50633(pdev->dev.parent);
128
129	pcf_bl->bl = backlight_device_register(pdev->name, &pdev->dev, pcf_bl,
130						&pcf50633_bl_ops, &bl_props);
131
132	if (IS_ERR(pcf_bl->bl)) {
133		ret = PTR_ERR(pcf_bl->bl);
134		goto err_free;
135	}
136
137	platform_set_drvdata(pdev, pcf_bl);
138
139	pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDDIM, pdata->ramp_time);
140
141	/* Should be different from bl_props.brightness, so we do not exit
142	 * update_status early the first time it's called */
143	pcf_bl->brightness = pcf_bl->bl->props.brightness + 1;
144
145	backlight_update_status(pcf_bl->bl);
146
147	return 0;
148
149err_free:
150	kfree(pcf_bl);
151
152	return ret;
153}
154
155static int __devexit pcf50633_bl_remove(struct platform_device *pdev)
156{
157	struct pcf50633_bl *pcf_bl = platform_get_drvdata(pdev);
158
159	backlight_device_unregister(pcf_bl->bl);
160
161	platform_set_drvdata(pdev, NULL);
162
163	kfree(pcf_bl);
164
165	return 0;
166}
167
168static struct platform_driver pcf50633_bl_driver = {
169	.probe =	pcf50633_bl_probe,
170	.remove =	__devexit_p(pcf50633_bl_remove),
171	.driver = {
172		.name = "pcf50633-backlight",
173	},
174};
175
176static int __init pcf50633_bl_init(void)
177{
178	return platform_driver_register(&pcf50633_bl_driver);
179}
180module_init(pcf50633_bl_init);
181
182static void __exit pcf50633_bl_exit(void)
183{
184	platform_driver_unregister(&pcf50633_bl_driver);
185}
186module_exit(pcf50633_bl_exit);
187
188MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
189MODULE_DESCRIPTION("PCF50633 backlight driver");
190MODULE_LICENSE("GPL");
191MODULE_ALIAS("platform:pcf50633-backlight");
192