fa00304a63d881a96e65e0937b24f25319a2a151
[~shefty/rdma-dev.git] / 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 being correctly configured
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 #include <linux/slab.h>
23
24 struct pwm_bl_data {
25         struct pwm_device       *pwm;
26         struct device           *dev;
27         unsigned int            period;
28         unsigned int            lth_brightness;
29         unsigned int            *levels;
30         int                     (*notify)(struct device *,
31                                           int brightness);
32         void                    (*notify_after)(struct device *,
33                                         int brightness);
34         int                     (*check_fb)(struct device *, struct fb_info *);
35         void                    (*exit)(struct device *);
36 };
37
38 static int pwm_backlight_update_status(struct backlight_device *bl)
39 {
40         struct pwm_bl_data *pb = bl_get_data(bl);
41         int brightness = bl->props.brightness;
42         int max = bl->props.max_brightness;
43
44         if (bl->props.power != FB_BLANK_UNBLANK ||
45             bl->props.fb_blank != FB_BLANK_UNBLANK ||
46             bl->props.state & BL_CORE_FBBLANK)
47                 brightness = 0;
48
49         if (pb->notify)
50                 brightness = pb->notify(pb->dev, brightness);
51
52         if (brightness == 0) {
53                 pwm_config(pb->pwm, 0, pb->period);
54                 pwm_disable(pb->pwm);
55         } else {
56                 int duty_cycle;
57
58                 if (pb->levels) {
59                         duty_cycle = pb->levels[brightness];
60                         max = pb->levels[max];
61                 } else {
62                         duty_cycle = brightness;
63                 }
64
65                 duty_cycle = pb->lth_brightness +
66                      (duty_cycle * (pb->period - pb->lth_brightness) / max);
67                 pwm_config(pb->pwm, duty_cycle, pb->period);
68                 pwm_enable(pb->pwm);
69         }
70
71         if (pb->notify_after)
72                 pb->notify_after(pb->dev, brightness);
73
74         return 0;
75 }
76
77 static int pwm_backlight_get_brightness(struct backlight_device *bl)
78 {
79         return bl->props.brightness;
80 }
81
82 static int pwm_backlight_check_fb(struct backlight_device *bl,
83                                   struct fb_info *info)
84 {
85         struct pwm_bl_data *pb = bl_get_data(bl);
86
87         return !pb->check_fb || pb->check_fb(pb->dev, info);
88 }
89
90 static const struct backlight_ops pwm_backlight_ops = {
91         .update_status  = pwm_backlight_update_status,
92         .get_brightness = pwm_backlight_get_brightness,
93         .check_fb       = pwm_backlight_check_fb,
94 };
95
96 #ifdef CONFIG_OF
97 static int pwm_backlight_parse_dt(struct device *dev,
98                                   struct platform_pwm_backlight_data *data)
99 {
100         struct device_node *node = dev->of_node;
101         struct property *prop;
102         int length;
103         u32 value;
104         int ret;
105
106         if (!node)
107                 return -ENODEV;
108
109         memset(data, 0, sizeof(*data));
110
111         /* determine the number of brightness levels */
112         prop = of_find_property(node, "brightness-levels", &length);
113         if (!prop)
114                 return -EINVAL;
115
116         data->max_brightness = length / sizeof(u32);
117
118         /* read brightness levels from DT property */
119         if (data->max_brightness > 0) {
120                 size_t size = sizeof(*data->levels) * data->max_brightness;
121
122                 data->levels = devm_kzalloc(dev, size, GFP_KERNEL);
123                 if (!data->levels)
124                         return -ENOMEM;
125
126                 ret = of_property_read_u32_array(node, "brightness-levels",
127                                                  data->levels,
128                                                  data->max_brightness);
129                 if (ret < 0)
130                         return ret;
131
132                 ret = of_property_read_u32(node, "default-brightness-level",
133                                            &value);
134                 if (ret < 0)
135                         return ret;
136
137                 data->dft_brightness = value;
138                 data->max_brightness--;
139         }
140
141         /*
142          * TODO: Most users of this driver use a number of GPIOs to control
143          *       backlight power. Support for specifying these needs to be
144          *       added.
145          */
146
147         return 0;
148 }
149
150 static struct of_device_id pwm_backlight_of_match[] = {
151         { .compatible = "pwm-backlight" },
152         { }
153 };
154
155 MODULE_DEVICE_TABLE(of, pwm_backlight_of_match);
156 #else
157 static int pwm_backlight_parse_dt(struct device *dev,
158                                   struct platform_pwm_backlight_data *data)
159 {
160         return -ENODEV;
161 }
162 #endif
163
164 static int pwm_backlight_probe(struct platform_device *pdev)
165 {
166         struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
167         struct platform_pwm_backlight_data defdata;
168         struct backlight_properties props;
169         struct backlight_device *bl;
170         struct pwm_bl_data *pb;
171         unsigned int max;
172         int ret;
173
174         if (!data) {
175                 ret = pwm_backlight_parse_dt(&pdev->dev, &defdata);
176                 if (ret < 0) {
177                         dev_err(&pdev->dev, "failed to find platform data\n");
178                         return ret;
179                 }
180
181                 data = &defdata;
182         }
183
184         if (data->init) {
185                 ret = data->init(&pdev->dev);
186                 if (ret < 0)
187                         return ret;
188         }
189
190         pb = devm_kzalloc(&pdev->dev, sizeof(*pb), GFP_KERNEL);
191         if (!pb) {
192                 dev_err(&pdev->dev, "no memory for state\n");
193                 ret = -ENOMEM;
194                 goto err_alloc;
195         }
196
197         if (data->levels) {
198                 max = data->levels[data->max_brightness];
199                 pb->levels = data->levels;
200         } else
201                 max = data->max_brightness;
202
203         pb->notify = data->notify;
204         pb->notify_after = data->notify_after;
205         pb->check_fb = data->check_fb;
206         pb->exit = data->exit;
207         pb->dev = &pdev->dev;
208
209         pb->pwm = devm_pwm_get(&pdev->dev, NULL);
210         if (IS_ERR(pb->pwm)) {
211                 dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
212
213                 pb->pwm = pwm_request(data->pwm_id, "pwm-backlight");
214                 if (IS_ERR(pb->pwm)) {
215                         dev_err(&pdev->dev, "unable to request legacy PWM\n");
216                         ret = PTR_ERR(pb->pwm);
217                         goto err_alloc;
218                 }
219         }
220
221         dev_dbg(&pdev->dev, "got pwm for backlight\n");
222
223         /*
224          * The DT case will set the pwm_period_ns field to 0 and store the
225          * period, parsed from the DT, in the PWM device. For the non-DT case,
226          * set the period from platform data.
227          */
228         if (data->pwm_period_ns > 0)
229                 pwm_set_period(pb->pwm, data->pwm_period_ns);
230
231         pb->period = pwm_get_period(pb->pwm);
232         pb->lth_brightness = data->lth_brightness * (pb->period / max);
233
234         memset(&props, 0, sizeof(struct backlight_properties));
235         props.type = BACKLIGHT_RAW;
236         props.max_brightness = data->max_brightness;
237         bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
238                                        &pwm_backlight_ops, &props);
239         if (IS_ERR(bl)) {
240                 dev_err(&pdev->dev, "failed to register backlight\n");
241                 ret = PTR_ERR(bl);
242                 goto err_alloc;
243         }
244
245         if (data->dft_brightness > data->max_brightness) {
246                 dev_warn(&pdev->dev,
247                          "invalid default brightness level: %u, using %u\n",
248                          data->dft_brightness, data->max_brightness);
249                 data->dft_brightness = data->max_brightness;
250         }
251
252         bl->props.brightness = data->dft_brightness;
253         backlight_update_status(bl);
254
255         platform_set_drvdata(pdev, bl);
256         return 0;
257
258 err_alloc:
259         if (data->exit)
260                 data->exit(&pdev->dev);
261         return ret;
262 }
263
264 static int pwm_backlight_remove(struct platform_device *pdev)
265 {
266         struct backlight_device *bl = platform_get_drvdata(pdev);
267         struct pwm_bl_data *pb = bl_get_data(bl);
268
269         backlight_device_unregister(bl);
270         pwm_config(pb->pwm, 0, pb->period);
271         pwm_disable(pb->pwm);
272         if (pb->exit)
273                 pb->exit(&pdev->dev);
274         return 0;
275 }
276
277 #ifdef CONFIG_PM
278 static int pwm_backlight_suspend(struct device *dev)
279 {
280         struct backlight_device *bl = dev_get_drvdata(dev);
281         struct pwm_bl_data *pb = bl_get_data(bl);
282
283         if (pb->notify)
284                 pb->notify(pb->dev, 0);
285         pwm_config(pb->pwm, 0, pb->period);
286         pwm_disable(pb->pwm);
287         if (pb->notify_after)
288                 pb->notify_after(pb->dev, 0);
289         return 0;
290 }
291
292 static int pwm_backlight_resume(struct device *dev)
293 {
294         struct backlight_device *bl = dev_get_drvdata(dev);
295
296         backlight_update_status(bl);
297         return 0;
298 }
299
300 static SIMPLE_DEV_PM_OPS(pwm_backlight_pm_ops, pwm_backlight_suspend,
301                          pwm_backlight_resume);
302
303 #endif
304
305 static struct platform_driver pwm_backlight_driver = {
306         .driver         = {
307                 .name           = "pwm-backlight",
308                 .owner          = THIS_MODULE,
309 #ifdef CONFIG_PM
310                 .pm             = &pwm_backlight_pm_ops,
311 #endif
312                 .of_match_table = of_match_ptr(pwm_backlight_of_match),
313         },
314         .probe          = pwm_backlight_probe,
315         .remove         = pwm_backlight_remove,
316 };
317
318 module_platform_driver(pwm_backlight_driver);
319
320 MODULE_DESCRIPTION("PWM based Backlight Driver");
321 MODULE_LICENSE("GPL");
322 MODULE_ALIAS("platform:pwm-backlight");
323