regulator, mc13xxx: Remove pointless test for unsigned less than zero
[zen-stable.git] / drivers / video / backlight / pwm_bl.c
blob21866ec69656d6be90e69af18a56316895f9d69f
1 /*
2 * linux/drivers/video/backlight/pwm_bl.c
4 * simple PWM based backlight control, board code has to setup
5 * 1) pin configuration so PWM waveforms can output
6 * 2) platform_data being correctly configured
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.
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 #include <linux/slab.h>
24 struct pwm_bl_data {
25 struct pwm_device *pwm;
26 struct device *dev;
27 unsigned int period;
28 unsigned int lth_brightness;
29 int (*notify)(struct device *,
30 int brightness);
33 static int pwm_backlight_update_status(struct backlight_device *bl)
35 struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
36 int brightness = bl->props.brightness;
37 int max = bl->props.max_brightness;
39 if (bl->props.power != FB_BLANK_UNBLANK)
40 brightness = 0;
42 if (bl->props.fb_blank != FB_BLANK_UNBLANK)
43 brightness = 0;
45 if (pb->notify)
46 brightness = pb->notify(pb->dev, brightness);
48 if (brightness == 0) {
49 pwm_config(pb->pwm, 0, pb->period);
50 pwm_disable(pb->pwm);
51 } else {
52 brightness = pb->lth_brightness +
53 (brightness * (pb->period - pb->lth_brightness) / max);
54 pwm_config(pb->pwm, brightness, pb->period);
55 pwm_enable(pb->pwm);
57 return 0;
60 static int pwm_backlight_get_brightness(struct backlight_device *bl)
62 return bl->props.brightness;
65 static const struct backlight_ops pwm_backlight_ops = {
66 .update_status = pwm_backlight_update_status,
67 .get_brightness = pwm_backlight_get_brightness,
70 static int pwm_backlight_probe(struct platform_device *pdev)
72 struct backlight_properties props;
73 struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
74 struct backlight_device *bl;
75 struct pwm_bl_data *pb;
76 int ret;
78 if (!data) {
79 dev_err(&pdev->dev, "failed to find platform data\n");
80 return -EINVAL;
83 if (data->init) {
84 ret = data->init(&pdev->dev);
85 if (ret < 0)
86 return ret;
89 pb = kzalloc(sizeof(*pb), GFP_KERNEL);
90 if (!pb) {
91 dev_err(&pdev->dev, "no memory for state\n");
92 ret = -ENOMEM;
93 goto err_alloc;
96 pb->period = data->pwm_period_ns;
97 pb->notify = data->notify;
98 pb->lth_brightness = data->lth_brightness *
99 (data->pwm_period_ns / data->max_brightness);
100 pb->dev = &pdev->dev;
102 pb->pwm = pwm_request(data->pwm_id, "backlight");
103 if (IS_ERR(pb->pwm)) {
104 dev_err(&pdev->dev, "unable to request PWM for backlight\n");
105 ret = PTR_ERR(pb->pwm);
106 goto err_pwm;
107 } else
108 dev_dbg(&pdev->dev, "got pwm for backlight\n");
110 memset(&props, 0, sizeof(struct backlight_properties));
111 props.max_brightness = data->max_brightness;
112 bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
113 &pwm_backlight_ops, &props);
114 if (IS_ERR(bl)) {
115 dev_err(&pdev->dev, "failed to register backlight\n");
116 ret = PTR_ERR(bl);
117 goto err_bl;
120 bl->props.brightness = data->dft_brightness;
121 backlight_update_status(bl);
123 platform_set_drvdata(pdev, bl);
124 return 0;
126 err_bl:
127 pwm_free(pb->pwm);
128 err_pwm:
129 kfree(pb);
130 err_alloc:
131 if (data->exit)
132 data->exit(&pdev->dev);
133 return ret;
136 static int pwm_backlight_remove(struct platform_device *pdev)
138 struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
139 struct backlight_device *bl = platform_get_drvdata(pdev);
140 struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
142 backlight_device_unregister(bl);
143 pwm_config(pb->pwm, 0, pb->period);
144 pwm_disable(pb->pwm);
145 pwm_free(pb->pwm);
146 kfree(pb);
147 if (data->exit)
148 data->exit(&pdev->dev);
149 return 0;
152 #ifdef CONFIG_PM
153 static int pwm_backlight_suspend(struct platform_device *pdev,
154 pm_message_t state)
156 struct backlight_device *bl = platform_get_drvdata(pdev);
157 struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
159 if (pb->notify)
160 pb->notify(pb->dev, 0);
161 pwm_config(pb->pwm, 0, pb->period);
162 pwm_disable(pb->pwm);
163 return 0;
166 static int pwm_backlight_resume(struct platform_device *pdev)
168 struct backlight_device *bl = platform_get_drvdata(pdev);
170 backlight_update_status(bl);
171 return 0;
173 #else
174 #define pwm_backlight_suspend NULL
175 #define pwm_backlight_resume NULL
176 #endif
178 static struct platform_driver pwm_backlight_driver = {
179 .driver = {
180 .name = "pwm-backlight",
181 .owner = THIS_MODULE,
183 .probe = pwm_backlight_probe,
184 .remove = pwm_backlight_remove,
185 .suspend = pwm_backlight_suspend,
186 .resume = pwm_backlight_resume,
189 static int __init pwm_backlight_init(void)
191 return platform_driver_register(&pwm_backlight_driver);
193 module_init(pwm_backlight_init);
195 static void __exit pwm_backlight_exit(void)
197 platform_driver_unregister(&pwm_backlight_driver);
199 module_exit(pwm_backlight_exit);
201 MODULE_DESCRIPTION("PWM based Backlight Driver");
202 MODULE_LICENSE("GPL");
203 MODULE_ALIAS("platform:pwm-backlight");