Linux Kernel  3.7.1
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
pcf50633-backlight.c
Go to the documentation of this file.
1 /*
2  * Copyright (C) 2009-2010, Lars-Peter Clausen <[email protected]>
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 
26 
27 struct pcf50633_bl {
28  struct pcf50633 *pcf;
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  */
45 int 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 
58 static 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) {
78  new_brightness);
79  if (!pcf_bl->brightness)
81  } else {
83  }
84 
85  pcf_bl->brightness = new_brightness;
86 
87  return 0;
88 }
89 
90 static 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 
96 static 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 
102 static int __devinit pcf50633_bl_probe(struct platform_device *pdev)
103 {
104  struct pcf50633_bl *pcf_bl;
105  struct device *parent = pdev->dev.parent;
106  struct pcf50633_platform_data *pcf50633_data = parent->platform_data;
107  struct pcf50633_bl_platform_data *pdata = pcf50633_data->backlight_data;
108  struct backlight_properties bl_props;
109 
110  pcf_bl = devm_kzalloc(&pdev->dev, sizeof(*pcf_bl), GFP_KERNEL);
111  if (!pcf_bl)
112  return -ENOMEM;
113 
114  memset(&bl_props, 0, sizeof(bl_props));
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  return PTR_ERR(pcf_bl->bl);
134 
135  platform_set_drvdata(pdev, pcf_bl);
136 
137  pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDDIM, pdata->ramp_time);
138 
139  /* Should be different from bl_props.brightness, so we do not exit
140  * update_status early the first time it's called */
141  pcf_bl->brightness = pcf_bl->bl->props.brightness + 1;
142 
143  backlight_update_status(pcf_bl->bl);
144 
145  return 0;
146 }
147 
148 static int __devexit pcf50633_bl_remove(struct platform_device *pdev)
149 {
150  struct pcf50633_bl *pcf_bl = platform_get_drvdata(pdev);
151 
153 
154  platform_set_drvdata(pdev, NULL);
155 
156  return 0;
157 }
158 
159 static struct platform_driver pcf50633_bl_driver = {
160  .probe = pcf50633_bl_probe,
161  .remove = __devexit_p(pcf50633_bl_remove),
162  .driver = {
163  .name = "pcf50633-backlight",
164  },
165 };
166 
167 module_platform_driver(pcf50633_bl_driver);
168 
169 MODULE_AUTHOR("Lars-Peter Clausen <[email protected]>");
170 MODULE_DESCRIPTION("PCF50633 backlight driver");
171 MODULE_LICENSE("GPL");
172 MODULE_ALIAS("platform:pcf50633-backlight");