Merge branch 'linus' into core/generic-dma-coherent
[linux-2.6] / drivers / video / backlight / pwm_bl.c
1 /*
2  * linux/drivers/video/backlight/pwm_bl.c
3  *
4  * simple PWM based backlight control, board code has to setup
5  * 1) pin configuration so PWM waveforms can output
6  * 2) platform_data casts to the PWM id (0/1/2/3 on PXA)
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  */
12
13 #include <linux/module.h>
14 #include <linux/kernel.h>
15 #include <linux/init.h>
16 #include <linux/platform_device.h>
17 #include <linux/fb.h>
18 #include <linux/backlight.h>
19 #include <linux/err.h>
20 #include <linux/pwm.h>
21 #include <linux/pwm_backlight.h>
22
23 struct pwm_bl_data {
24         struct pwm_device       *pwm;
25         unsigned int            period;
26         int                     (*notify)(int brightness);
27 };
28
29 static int pwm_backlight_update_status(struct backlight_device *bl)
30 {
31         struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
32         int brightness = bl->props.brightness;
33         int max = bl->props.max_brightness;
34
35         if (bl->props.power != FB_BLANK_UNBLANK)
36                 brightness = 0;
37
38         if (bl->props.fb_blank != FB_BLANK_UNBLANK)
39                 brightness = 0;
40
41         if (pb->notify)
42                 brightness = pb->notify(brightness);
43
44         if (brightness == 0) {
45                 pwm_config(pb->pwm, 0, pb->period);
46                 pwm_disable(pb->pwm);
47         } else {
48                 pwm_config(pb->pwm, brightness * pb->period / max, pb->period);
49                 pwm_enable(pb->pwm);
50         }
51         return 0;
52 }
53
54 static int pwm_backlight_get_brightness(struct backlight_device *bl)
55 {
56         return bl->props.brightness;
57 }
58
59 static struct backlight_ops pwm_backlight_ops = {
60         .update_status  = pwm_backlight_update_status,
61         .get_brightness = pwm_backlight_get_brightness,
62 };
63
64 static int pwm_backlight_probe(struct platform_device *pdev)
65 {
66         struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
67         struct backlight_device *bl;
68         struct pwm_bl_data *pb;
69         int ret;
70
71         if (!data)
72                 return -EINVAL;
73
74         if (data->init) {
75                 ret = data->init(&pdev->dev);
76                 if (ret < 0)
77                         return ret;
78         }
79
80         pb = kzalloc(sizeof(*pb), GFP_KERNEL);
81         if (!pb) {
82                 ret = -ENOMEM;
83                 goto err_alloc;
84         }
85
86         pb->period = data->pwm_period_ns;
87         pb->notify = data->notify;
88
89         pb->pwm = pwm_request(data->pwm_id, "backlight");
90         if (IS_ERR(pb->pwm)) {
91                 dev_err(&pdev->dev, "unable to request PWM for backlight\n");
92                 ret = PTR_ERR(pb->pwm);
93                 goto err_pwm;
94         }
95
96         bl = backlight_device_register(pdev->name, &pdev->dev,
97                         pb, &pwm_backlight_ops);
98         if (IS_ERR(bl)) {
99                 dev_err(&pdev->dev, "failed to register backlight\n");
100                 ret = PTR_ERR(bl);
101                 goto err_bl;
102         }
103
104         bl->props.max_brightness = data->max_brightness;
105         bl->props.brightness = data->dft_brightness;
106         backlight_update_status(bl);
107
108         platform_set_drvdata(pdev, bl);
109         return 0;
110
111 err_bl:
112         pwm_free(pb->pwm);
113 err_pwm:
114         kfree(pb);
115 err_alloc:
116         if (data->exit)
117                 data->exit(&pdev->dev);
118         return ret;
119 }
120
121 static int pwm_backlight_remove(struct platform_device *pdev)
122 {
123         struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
124         struct backlight_device *bl = platform_get_drvdata(pdev);
125         struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
126
127         backlight_device_unregister(bl);
128         pwm_config(pb->pwm, 0, pb->period);
129         pwm_disable(pb->pwm);
130         pwm_free(pb->pwm);
131         kfree(pb);
132         if (data->exit)
133                 data->exit(&pdev->dev);
134         return 0;
135 }
136
137 #ifdef CONFIG_PM
138 static int pwm_backlight_suspend(struct platform_device *pdev,
139                                  pm_message_t state)
140 {
141         struct backlight_device *bl = platform_get_drvdata(pdev);
142         struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
143
144         pwm_config(pb->pwm, 0, pb->period);
145         pwm_disable(pb->pwm);
146         return 0;
147 }
148
149 static int pwm_backlight_resume(struct platform_device *pdev)
150 {
151         struct backlight_device *bl = platform_get_drvdata(pdev);
152
153         backlight_update_status(bl);
154         return 0;
155 }
156 #else
157 #define pwm_backlight_suspend   NULL
158 #define pwm_backlight_resume    NULL
159 #endif
160
161 static struct platform_driver pwm_backlight_driver = {
162         .driver         = {
163                 .name   = "pwm-backlight",
164                 .owner  = THIS_MODULE,
165         },
166         .probe          = pwm_backlight_probe,
167         .remove         = pwm_backlight_remove,
168         .suspend        = pwm_backlight_suspend,
169         .resume         = pwm_backlight_resume,
170 };
171
172 static int __init pwm_backlight_init(void)
173 {
174         return platform_driver_register(&pwm_backlight_driver);
175 }
176 module_init(pwm_backlight_init);
177
178 static void __exit pwm_backlight_exit(void)
179 {
180         platform_driver_unregister(&pwm_backlight_driver);
181 }
182 module_exit(pwm_backlight_exit);
183
184 MODULE_DESCRIPTION("PWM based Backlight Driver");
185 MODULE_LICENSE("GPL");