f2f4c43d6e22894ef2e98d6c0eff0a9688f701fd
[~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                 brightness = 0;
46
47         if (bl->props.fb_blank != FB_BLANK_UNBLANK)
48                 brightness = 0;
49
50         if (pb->notify)
51                 brightness = pb->notify(pb->dev, brightness);
52
53         if (brightness == 0) {
54                 pwm_config(pb->pwm, 0, pb->period);
55                 pwm_disable(pb->pwm);
56         } else {
57                 int duty_cycle;
58
59                 if (pb->levels) {
60                         duty_cycle = pb->levels[brightness];
61                         max = pb->levels[max];
62                 } else {
63                         duty_cycle = brightness;
64                 }
65
66                 duty_cycle = pb->lth_brightness +
67                      (duty_cycle * (pb->period - pb->lth_brightness) / max);
68                 pwm_config(pb->pwm, duty_cycle, pb->period);
69                 pwm_enable(pb->pwm);
70         }
71
72         if (pb->notify_after)
73                 pb->notify_after(pb->dev, brightness);
74
75         return 0;
76 }
77
78 static int pwm_backlight_get_brightness(struct backlight_device *bl)
79 {
80         return bl->props.brightness;
81 }
82
83 static int pwm_backlight_check_fb(struct backlight_device *bl,
84                                   struct fb_info *info)
85 {
86         struct pwm_bl_data *pb = bl_get_data(bl);
87
88         return !pb->check_fb || pb->check_fb(pb->dev, info);
89 }
90
91 static const struct backlight_ops pwm_backlight_ops = {
92         .update_status  = pwm_backlight_update_status,
93         .get_brightness = pwm_backlight_get_brightness,
94         .check_fb       = pwm_backlight_check_fb,
95 };
96
97 #ifdef CONFIG_OF
98 static int pwm_backlight_parse_dt(struct device *dev,
99                                   struct platform_pwm_backlight_data *data)
100 {
101         struct device_node *node = dev->of_node;
102         struct property *prop;
103         int length;
104         u32 value;
105         int ret;
106
107         if (!node)
108                 return -ENODEV;
109
110         memset(data, 0, sizeof(*data));
111
112         /* determine the number of brightness levels */
113         prop = of_find_property(node, "brightness-levels", &length);
114         if (!prop)
115                 return -EINVAL;
116
117         data->max_brightness = length / sizeof(u32);
118
119         /* read brightness levels from DT property */
120         if (data->max_brightness > 0) {
121                 size_t size = sizeof(*data->levels) * data->max_brightness;
122
123                 data->levels = devm_kzalloc(dev, size, GFP_KERNEL);
124                 if (!data->levels)
125                         return -ENOMEM;
126
127                 ret = of_property_read_u32_array(node, "brightness-levels",
128                                                  data->levels,
129                                                  data->max_brightness);
130                 if (ret < 0)
131                         return ret;
132
133                 ret = of_property_read_u32(node, "default-brightness-level",
134                                            &value);
135                 if (ret < 0)
136                         return ret;
137
138                 if (value >= data->max_brightness) {
139                         dev_warn(dev, "invalid default brightness level: %u, using %u\n",
140                                  value, data->max_brightness - 1);
141                         value = data->max_brightness - 1;
142                 }
143
144                 data->dft_brightness = value;
145                 data->max_brightness--;
146         }
147
148         /*
149          * TODO: Most users of this driver use a number of GPIOs to control
150          *       backlight power. Support for specifying these needs to be
151          *       added.
152          */
153
154         return 0;
155 }
156
157 static struct of_device_id pwm_backlight_of_match[] = {
158         { .compatible = "pwm-backlight" },
159         { }
160 };
161
162 MODULE_DEVICE_TABLE(of, pwm_backlight_of_match);
163 #else
164 static int pwm_backlight_parse_dt(struct device *dev,
165                                   struct platform_pwm_backlight_data *data)
166 {
167         return -ENODEV;
168 }
169 #endif
170
171 static int pwm_backlight_probe(struct platform_device *pdev)
172 {
173         struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
174         struct platform_pwm_backlight_data defdata;
175         struct backlight_properties props;
176         struct backlight_device *bl;
177         struct pwm_bl_data *pb;
178         unsigned int max;
179         int ret;
180
181         if (!data) {
182                 ret = pwm_backlight_parse_dt(&pdev->dev, &defdata);
183                 if (ret < 0) {
184                         dev_err(&pdev->dev, "failed to find platform data\n");
185                         return ret;
186                 }
187
188                 data = &defdata;
189         }
190
191         if (data->init) {
192                 ret = data->init(&pdev->dev);
193                 if (ret < 0)
194                         return ret;
195         }
196
197         pb = devm_kzalloc(&pdev->dev, sizeof(*pb), GFP_KERNEL);
198         if (!pb) {
199                 dev_err(&pdev->dev, "no memory for state\n");
200                 ret = -ENOMEM;
201                 goto err_alloc;
202         }
203
204         if (data->levels) {
205                 max = data->levels[data->max_brightness];
206                 pb->levels = data->levels;
207         } else
208                 max = data->max_brightness;
209
210         pb->notify = data->notify;
211         pb->notify_after = data->notify_after;
212         pb->check_fb = data->check_fb;
213         pb->exit = data->exit;
214         pb->dev = &pdev->dev;
215
216         pb->pwm = devm_pwm_get(&pdev->dev, NULL);
217         if (IS_ERR(pb->pwm)) {
218                 dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
219
220                 pb->pwm = pwm_request(data->pwm_id, "pwm-backlight");
221                 if (IS_ERR(pb->pwm)) {
222                         dev_err(&pdev->dev, "unable to request legacy PWM\n");
223                         ret = PTR_ERR(pb->pwm);
224                         goto err_alloc;
225                 }
226         }
227
228         dev_dbg(&pdev->dev, "got pwm for backlight\n");
229
230         /*
231          * The DT case will set the pwm_period_ns field to 0 and store the
232          * period, parsed from the DT, in the PWM device. For the non-DT case,
233          * set the period from platform data.
234          */
235         if (data->pwm_period_ns > 0)
236                 pwm_set_period(pb->pwm, data->pwm_period_ns);
237
238         pb->period = pwm_get_period(pb->pwm);
239         pb->lth_brightness = data->lth_brightness * (pb->period / max);
240
241         memset(&props, 0, sizeof(struct backlight_properties));
242         props.type = BACKLIGHT_RAW;
243         props.max_brightness = data->max_brightness;
244         bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
245                                        &pwm_backlight_ops, &props);
246         if (IS_ERR(bl)) {
247                 dev_err(&pdev->dev, "failed to register backlight\n");
248                 ret = PTR_ERR(bl);
249                 goto err_alloc;
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