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13#include <linux/gpio/consumer.h>
14#include <linux/gpio.h>
15#include <linux/module.h>
16#include <linux/kernel.h>
17#include <linux/init.h>
18#include <linux/platform_device.h>
19#include <linux/fb.h>
20#include <linux/backlight.h>
21#include <linux/err.h>
22#include <linux/pwm.h>
23#include <linux/pwm_backlight.h>
24#include <linux/regulator/consumer.h>
25#include <linux/slab.h>
26
27struct pwm_bl_data {
28 struct pwm_device *pwm;
29 struct device *dev;
30 unsigned int period;
31 unsigned int lth_brightness;
32 unsigned int *levels;
33 bool enabled;
34 struct regulator *power_supply;
35 struct gpio_desc *enable_gpio;
36 unsigned int scale;
37 bool legacy;
38 int (*notify)(struct device *,
39 int brightness);
40 void (*notify_after)(struct device *,
41 int brightness);
42 int (*check_fb)(struct device *, struct fb_info *);
43 void (*exit)(struct device *);
44};
45
46static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
47{
48 int err;
49
50 if (pb->enabled)
51 return;
52
53 err = regulator_enable(pb->power_supply);
54 if (err < 0)
55 dev_err(pb->dev, "failed to enable power supply\n");
56
57 if (pb->enable_gpio)
58 gpiod_set_value(pb->enable_gpio, 1);
59
60 pwm_enable(pb->pwm);
61 pb->enabled = true;
62}
63
64static void pwm_backlight_power_off(struct pwm_bl_data *pb)
65{
66 if (!pb->enabled)
67 return;
68
69 pwm_config(pb->pwm, 0, pb->period);
70 pwm_disable(pb->pwm);
71
72 if (pb->enable_gpio)
73 gpiod_set_value(pb->enable_gpio, 0);
74
75 regulator_disable(pb->power_supply);
76 pb->enabled = false;
77}
78
79static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)
80{
81 unsigned int lth = pb->lth_brightness;
82 int duty_cycle;
83
84 if (pb->levels)
85 duty_cycle = pb->levels[brightness];
86 else
87 duty_cycle = brightness;
88
89 return (duty_cycle * (pb->period - lth) / pb->scale) + lth;
90}
91
92static int pwm_backlight_update_status(struct backlight_device *bl)
93{
94 struct pwm_bl_data *pb = bl_get_data(bl);
95 int brightness = bl->props.brightness;
96 int duty_cycle;
97
98 if (bl->props.power != FB_BLANK_UNBLANK ||
99 bl->props.fb_blank != FB_BLANK_UNBLANK ||
100 bl->props.state & BL_CORE_FBBLANK)
101 brightness = 0;
102
103 if (pb->notify)
104 brightness = pb->notify(pb->dev, brightness);
105
106 if (brightness > 0) {
107 duty_cycle = compute_duty_cycle(pb, brightness);
108 pwm_config(pb->pwm, duty_cycle, pb->period);
109 pwm_backlight_power_on(pb, brightness);
110 } else
111 pwm_backlight_power_off(pb);
112
113 if (pb->notify_after)
114 pb->notify_after(pb->dev, brightness);
115
116 return 0;
117}
118
119static int pwm_backlight_check_fb(struct backlight_device *bl,
120 struct fb_info *info)
121{
122 struct pwm_bl_data *pb = bl_get_data(bl);
123
124 return !pb->check_fb || pb->check_fb(pb->dev, info);
125}
126
127static const struct backlight_ops pwm_backlight_ops = {
128 .update_status = pwm_backlight_update_status,
129 .check_fb = pwm_backlight_check_fb,
130};
131
132#ifdef CONFIG_OF
133static int pwm_backlight_parse_dt(struct device *dev,
134 struct platform_pwm_backlight_data *data)
135{
136 struct device_node *node = dev->of_node;
137 struct property *prop;
138 int length;
139 u32 value;
140 int ret;
141
142 if (!node)
143 return -ENODEV;
144
145 memset(data, 0, sizeof(*data));
146
147
148 prop = of_find_property(node, "brightness-levels", &length);
149 if (!prop)
150 return -EINVAL;
151
152 data->max_brightness = length / sizeof(u32);
153
154
155 if (data->max_brightness > 0) {
156 size_t size = sizeof(*data->levels) * data->max_brightness;
157
158 data->levels = devm_kzalloc(dev, size, GFP_KERNEL);
159 if (!data->levels)
160 return -ENOMEM;
161
162 ret = of_property_read_u32_array(node, "brightness-levels",
163 data->levels,
164 data->max_brightness);
165 if (ret < 0)
166 return ret;
167
168 ret = of_property_read_u32(node, "default-brightness-level",
169 &value);
170 if (ret < 0)
171 return ret;
172
173 data->dft_brightness = value;
174 data->max_brightness--;
175 }
176
177 data->enable_gpio = -EINVAL;
178 return 0;
179}
180
181static struct of_device_id pwm_backlight_of_match[] = {
182 { .compatible = "pwm-backlight" },
183 { }
184};
185
186MODULE_DEVICE_TABLE(of, pwm_backlight_of_match);
187#else
188static int pwm_backlight_parse_dt(struct device *dev,
189 struct platform_pwm_backlight_data *data)
190{
191 return -ENODEV;
192}
193#endif
194
195static int pwm_backlight_probe(struct platform_device *pdev)
196{
197 struct platform_pwm_backlight_data *data = dev_get_platdata(&pdev->dev);
198 struct platform_pwm_backlight_data defdata;
199 struct backlight_properties props;
200 struct backlight_device *bl;
201 struct device_node *node = pdev->dev.of_node;
202 struct pwm_bl_data *pb;
203 int initial_blank = FB_BLANK_UNBLANK;
204 int ret;
205
206 if (!data) {
207 ret = pwm_backlight_parse_dt(&pdev->dev, &defdata);
208 if (ret < 0) {
209 dev_err(&pdev->dev, "failed to find platform data\n");
210 return ret;
211 }
212
213 data = &defdata;
214 }
215
216 if (data->init) {
217 ret = data->init(&pdev->dev);
218 if (ret < 0)
219 return ret;
220 }
221
222 pb = devm_kzalloc(&pdev->dev, sizeof(*pb), GFP_KERNEL);
223 if (!pb) {
224 ret = -ENOMEM;
225 goto err_alloc;
226 }
227
228 if (data->levels) {
229 unsigned int i;
230
231 for (i = 0; i <= data->max_brightness; i++)
232 if (data->levels[i] > pb->scale)
233 pb->scale = data->levels[i];
234
235 pb->levels = data->levels;
236 } else
237 pb->scale = data->max_brightness;
238
239 pb->notify = data->notify;
240 pb->notify_after = data->notify_after;
241 pb->check_fb = data->check_fb;
242 pb->exit = data->exit;
243 pb->dev = &pdev->dev;
244 pb->enabled = false;
245
246 pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
247 GPIOD_ASIS);
248 if (IS_ERR(pb->enable_gpio)) {
249 ret = PTR_ERR(pb->enable_gpio);
250 goto err_alloc;
251 }
252
253
254
255
256
257 if (!pb->enable_gpio && gpio_is_valid(data->enable_gpio)) {
258 ret = devm_gpio_request_one(&pdev->dev, data->enable_gpio,
259 GPIOF_OUT_INIT_HIGH, "enable");
260 if (ret < 0) {
261 dev_err(&pdev->dev, "failed to request GPIO#%d: %d\n",
262 data->enable_gpio, ret);
263 goto err_alloc;
264 }
265
266 pb->enable_gpio = gpio_to_desc(data->enable_gpio);
267 }
268
269 if (pb->enable_gpio) {
270
271
272
273
274
275
276 if (node && node->phandle &&
277 gpiod_get_direction(pb->enable_gpio) == GPIOF_DIR_OUT &&
278 gpiod_get_value(pb->enable_gpio) == 0)
279 initial_blank = FB_BLANK_POWERDOWN;
280 else
281 gpiod_direction_output(pb->enable_gpio, 1);
282 }
283
284 pb->power_supply = devm_regulator_get(&pdev->dev, "power");
285 if (IS_ERR(pb->power_supply)) {
286 ret = PTR_ERR(pb->power_supply);
287 goto err_alloc;
288 }
289
290 if (node && node->phandle && !regulator_is_enabled(pb->power_supply))
291 initial_blank = FB_BLANK_POWERDOWN;
292
293 pb->pwm = devm_pwm_get(&pdev->dev, NULL);
294 if (IS_ERR(pb->pwm) && PTR_ERR(pb->pwm) != -EPROBE_DEFER && !node) {
295 dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
296 pb->legacy = true;
297 pb->pwm = pwm_request(data->pwm_id, "pwm-backlight");
298 }
299
300 if (IS_ERR(pb->pwm)) {
301 ret = PTR_ERR(pb->pwm);
302 if (ret != -EPROBE_DEFER)
303 dev_err(&pdev->dev, "unable to request PWM\n");
304 goto err_alloc;
305 }
306
307 dev_dbg(&pdev->dev, "got pwm for backlight\n");
308
309
310
311
312
313
314
315 pb->period = pwm_get_period(pb->pwm);
316 if (!pb->period && (data->pwm_period_ns > 0)) {
317 pb->period = data->pwm_period_ns;
318 pwm_set_period(pb->pwm, data->pwm_period_ns);
319 }
320
321 pb->lth_brightness = data->lth_brightness * (pb->period / pb->scale);
322
323 memset(&props, 0, sizeof(struct backlight_properties));
324 props.type = BACKLIGHT_RAW;
325 props.max_brightness = data->max_brightness;
326 bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
327 &pwm_backlight_ops, &props);
328 if (IS_ERR(bl)) {
329 dev_err(&pdev->dev, "failed to register backlight\n");
330 ret = PTR_ERR(bl);
331 if (pb->legacy)
332 pwm_free(pb->pwm);
333 goto err_alloc;
334 }
335
336 if (data->dft_brightness > data->max_brightness) {
337 dev_warn(&pdev->dev,
338 "invalid default brightness level: %u, using %u\n",
339 data->dft_brightness, data->max_brightness);
340 data->dft_brightness = data->max_brightness;
341 }
342
343 bl->props.brightness = data->dft_brightness;
344 bl->props.power = initial_blank;
345 backlight_update_status(bl);
346
347 platform_set_drvdata(pdev, bl);
348 return 0;
349
350err_alloc:
351 if (data->exit)
352 data->exit(&pdev->dev);
353 return ret;
354}
355
356static int pwm_backlight_remove(struct platform_device *pdev)
357{
358 struct backlight_device *bl = platform_get_drvdata(pdev);
359 struct pwm_bl_data *pb = bl_get_data(bl);
360
361 backlight_device_unregister(bl);
362 pwm_backlight_power_off(pb);
363
364 if (pb->exit)
365 pb->exit(&pdev->dev);
366 if (pb->legacy)
367 pwm_free(pb->pwm);
368
369 return 0;
370}
371
372static void pwm_backlight_shutdown(struct platform_device *pdev)
373{
374 struct backlight_device *bl = platform_get_drvdata(pdev);
375 struct pwm_bl_data *pb = bl_get_data(bl);
376
377 pwm_backlight_power_off(pb);
378}
379
380#ifdef CONFIG_PM_SLEEP
381static int pwm_backlight_suspend(struct device *dev)
382{
383 struct backlight_device *bl = dev_get_drvdata(dev);
384 struct pwm_bl_data *pb = bl_get_data(bl);
385
386 if (pb->notify)
387 pb->notify(pb->dev, 0);
388
389 pwm_backlight_power_off(pb);
390
391 if (pb->notify_after)
392 pb->notify_after(pb->dev, 0);
393
394 return 0;
395}
396
397static int pwm_backlight_resume(struct device *dev)
398{
399 struct backlight_device *bl = dev_get_drvdata(dev);
400
401 backlight_update_status(bl);
402
403 return 0;
404}
405#endif
406
407static const struct dev_pm_ops pwm_backlight_pm_ops = {
408#ifdef CONFIG_PM_SLEEP
409 .suspend = pwm_backlight_suspend,
410 .resume = pwm_backlight_resume,
411 .poweroff = pwm_backlight_suspend,
412 .restore = pwm_backlight_resume,
413#endif
414};
415
416static struct platform_driver pwm_backlight_driver = {
417 .driver = {
418 .name = "pwm-backlight",
419 .pm = &pwm_backlight_pm_ops,
420 .of_match_table = of_match_ptr(pwm_backlight_of_match),
421 },
422 .probe = pwm_backlight_probe,
423 .remove = pwm_backlight_remove,
424 .shutdown = pwm_backlight_shutdown,
425};
426
427module_platform_driver(pwm_backlight_driver);
428
429MODULE_DESCRIPTION("PWM based Backlight Driver");
430MODULE_LICENSE("GPL");
431MODULE_ALIAS("platform:pwm-backlight");
432
