1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * LED driver for Richtek RT8515 flash/torch white LEDs
4 * found on some Samsung mobile phones.
5 *
6 * This is a 1.5A Boost dual channel driver produced around 2011.
7 *
8 * The component lacks a datasheet, but in the schematic picture
9 * from the LG P970 service manual you can see the connections
10 * from the RT8515 to the LED, with two resistors connected
11 * from the pins "RFS" and "RTS" to ground.
12 *
13 * On the LG P970:
14 * RFS (resistance flash setting?) is 20 kOhm
15 * RTS (resistance torch setting?) is 39 kOhm
16 *
17 * Some sleuthing finds us the RT9387A which we have a datasheet for:
18 * https://static5.arrow.com/pdfs/2014/7/27/8/21/12/794/rtt_/manual/94download_ds.jspprt9387a.jspprt9387a.pdf
19 * This apparently works the same way so in theory this driver
20 * should cover RT9387A as well. This has not been tested, please
21 * update the compatibles if you add RT9387A support.
22 *
23 * Linus Walleij <linus.walleij@linaro.org>
24 */
25 #include <linux/delay.h>
26 #include <linux/err.h>
27 #include <linux/gpio/consumer.h>
28 #include <linux/led-class-flash.h>
29 #include <linux/mod_devicetable.h>
30 #include <linux/module.h>
31 #include <linux/platform_device.h>
32 #include <linux/property.h>
33 #include <linux/regulator/consumer.h>
34
35 #include <media/v4l2-flash-led-class.h>
36
37 /* We can provide 15-700 mA out to the LED */
38 #define RT8515_MIN_IOUT_MA 15
39 #define RT8515_MAX_IOUT_MA 700
40 /* The maximum intensity is 1-16 for flash and 1-100 for torch */
41 #define RT8515_FLASH_MAX 16
42 #define RT8515_TORCH_MAX 100
43
44 #define RT8515_TIMEOUT_US 250000U
45 #define RT8515_MAX_TIMEOUT_US 300000U
46
47 struct rt8515 {
48 struct led_classdev_flash fled;
49 struct device *dev;
50 struct v4l2_flash *v4l2_flash;
51 struct mutex lock;
52 struct regulator *reg;
53 struct gpio_desc *enable_torch;
54 struct gpio_desc *enable_flash;
55 struct timer_list powerdown_timer;
56 u32 max_timeout; /* Flash max timeout */
57 int flash_max_intensity;
58 int torch_max_intensity;
59 };
60
to_rt8515(struct led_classdev_flash * fled)61 static struct rt8515 *to_rt8515(struct led_classdev_flash *fled)
62 {
63 return container_of(fled, struct rt8515, fled);
64 }
65
rt8515_gpio_led_off(struct rt8515 * rt)66 static void rt8515_gpio_led_off(struct rt8515 *rt)
67 {
68 gpiod_set_value(rt->enable_flash, 0);
69 gpiod_set_value(rt->enable_torch, 0);
70 }
71
rt8515_gpio_brightness_commit(struct gpio_desc * gpiod,int brightness)72 static void rt8515_gpio_brightness_commit(struct gpio_desc *gpiod,
73 int brightness)
74 {
75 int i;
76
77 /*
78 * Toggling a GPIO line with a small delay increases the
79 * brightness one step at a time.
80 */
81 for (i = 0; i < brightness; i++) {
82 gpiod_set_value(gpiod, 0);
83 udelay(1);
84 gpiod_set_value(gpiod, 1);
85 udelay(1);
86 }
87 }
88
89 /* This is setting the torch light level */
rt8515_led_brightness_set(struct led_classdev * led,enum led_brightness brightness)90 static int rt8515_led_brightness_set(struct led_classdev *led,
91 enum led_brightness brightness)
92 {
93 struct led_classdev_flash *fled = lcdev_to_flcdev(led);
94 struct rt8515 *rt = to_rt8515(fled);
95
96 mutex_lock(&rt->lock);
97
98 if (brightness == LED_OFF) {
99 /* Off */
100 rt8515_gpio_led_off(rt);
101 } else if (brightness < RT8515_TORCH_MAX) {
102 /* Step it up to movie mode brightness using the flash pin */
103 rt8515_gpio_brightness_commit(rt->enable_torch, brightness);
104 } else {
105 /* Max torch brightness requested */
106 gpiod_set_value(rt->enable_torch, 1);
107 }
108
109 mutex_unlock(&rt->lock);
110
111 return 0;
112 }
113
rt8515_led_flash_strobe_set(struct led_classdev_flash * fled,bool state)114 static int rt8515_led_flash_strobe_set(struct led_classdev_flash *fled,
115 bool state)
116 {
117 struct rt8515 *rt = to_rt8515(fled);
118 struct led_flash_setting *timeout = &fled->timeout;
119 int brightness = rt->flash_max_intensity;
120
121 mutex_lock(&rt->lock);
122
123 if (state) {
124 /* Enable LED flash mode and set brightness */
125 rt8515_gpio_brightness_commit(rt->enable_flash, brightness);
126 /* Set timeout */
127 mod_timer(&rt->powerdown_timer,
128 jiffies + usecs_to_jiffies(timeout->val));
129 } else {
130 del_timer_sync(&rt->powerdown_timer);
131 /* Turn the LED off */
132 rt8515_gpio_led_off(rt);
133 }
134
135 fled->led_cdev.brightness = LED_OFF;
136 /* After this the torch LED will be disabled */
137
138 mutex_unlock(&rt->lock);
139
140 return 0;
141 }
142
rt8515_led_flash_strobe_get(struct led_classdev_flash * fled,bool * state)143 static int rt8515_led_flash_strobe_get(struct led_classdev_flash *fled,
144 bool *state)
145 {
146 struct rt8515 *rt = to_rt8515(fled);
147
148 *state = timer_pending(&rt->powerdown_timer);
149
150 return 0;
151 }
152
rt8515_led_flash_timeout_set(struct led_classdev_flash * fled,u32 timeout)153 static int rt8515_led_flash_timeout_set(struct led_classdev_flash *fled,
154 u32 timeout)
155 {
156 /* The timeout is stored in the led-class-flash core */
157 return 0;
158 }
159
160 static const struct led_flash_ops rt8515_flash_ops = {
161 .strobe_set = rt8515_led_flash_strobe_set,
162 .strobe_get = rt8515_led_flash_strobe_get,
163 .timeout_set = rt8515_led_flash_timeout_set,
164 };
165
rt8515_powerdown_timer(struct timer_list * t)166 static void rt8515_powerdown_timer(struct timer_list *t)
167 {
168 struct rt8515 *rt = from_timer(rt, t, powerdown_timer);
169
170 /* Turn the LED off */
171 rt8515_gpio_led_off(rt);
172 }
173
rt8515_init_flash_timeout(struct rt8515 * rt)174 static void rt8515_init_flash_timeout(struct rt8515 *rt)
175 {
176 struct led_classdev_flash *fled = &rt->fled;
177 struct led_flash_setting *s;
178
179 /* Init flash timeout setting */
180 s = &fled->timeout;
181 s->min = 1;
182 s->max = rt->max_timeout;
183 s->step = 1;
184 /*
185 * Set default timeout to RT8515_TIMEOUT_US except if
186 * max_timeout from DT is lower.
187 */
188 s->val = min(rt->max_timeout, RT8515_TIMEOUT_US);
189 }
190
191 #if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
192 /* Configure the V2L2 flash subdevice */
rt8515_init_v4l2_flash_config(struct rt8515 * rt,struct v4l2_flash_config * v4l2_sd_cfg)193 static void rt8515_init_v4l2_flash_config(struct rt8515 *rt,
194 struct v4l2_flash_config *v4l2_sd_cfg)
195 {
196 struct led_classdev *led = &rt->fled.led_cdev;
197 struct led_flash_setting *s;
198
199 strscpy(v4l2_sd_cfg->dev_name, led->dev->kobj.name,
200 sizeof(v4l2_sd_cfg->dev_name));
201
202 /*
203 * Init flash intensity setting: this is a linear scale
204 * capped from the device tree max intensity setting
205 * 1..flash_max_intensity
206 */
207 s = &v4l2_sd_cfg->intensity;
208 s->min = 1;
209 s->max = rt->flash_max_intensity;
210 s->step = 1;
211 s->val = s->max;
212 }
213
rt8515_v4l2_flash_release(struct rt8515 * rt)214 static void rt8515_v4l2_flash_release(struct rt8515 *rt)
215 {
216 v4l2_flash_release(rt->v4l2_flash);
217 }
218
219 #else
rt8515_init_v4l2_flash_config(struct rt8515 * rt,struct v4l2_flash_config * v4l2_sd_cfg)220 static void rt8515_init_v4l2_flash_config(struct rt8515 *rt,
221 struct v4l2_flash_config *v4l2_sd_cfg)
222 {
223 }
224
rt8515_v4l2_flash_release(struct rt8515 * rt)225 static void rt8515_v4l2_flash_release(struct rt8515 *rt)
226 {
227 }
228 #endif
229
rt8515_determine_max_intensity(struct rt8515 * rt,struct fwnode_handle * led,const char * resistance,const char * max_ua_prop,int hw_max,int * max_intensity_setting)230 static void rt8515_determine_max_intensity(struct rt8515 *rt,
231 struct fwnode_handle *led,
232 const char *resistance,
233 const char *max_ua_prop, int hw_max,
234 int *max_intensity_setting)
235 {
236 u32 res = 0; /* Can't be 0 so 0 is undefined */
237 u32 ua;
238 u32 max_ma;
239 int max_intensity;
240 int ret;
241
242 fwnode_property_read_u32(rt->dev->fwnode, resistance, &res);
243 ret = fwnode_property_read_u32(led, max_ua_prop, &ua);
244
245 /* Missing info in DT, OK go with hardware maxima */
246 if (ret || res == 0) {
247 dev_err(rt->dev,
248 "either %s or %s missing from DT, using HW max\n",
249 resistance, max_ua_prop);
250 max_ma = RT8515_MAX_IOUT_MA;
251 max_intensity = hw_max;
252 goto out_assign_max;
253 }
254
255 /*
256 * Formula from the datasheet, this is the maximum current
257 * defined by the hardware.
258 */
259 max_ma = (5500 * 1000) / res;
260 /*
261 * Calculate max intensity (linear scaling)
262 * Formula is ((ua / 1000) / max_ma) * 100, then simplified
263 */
264 max_intensity = (ua / 10) / max_ma;
265
266 dev_info(rt->dev,
267 "current restricted from %u to %u mA, max intensity %d/100\n",
268 max_ma, (ua / 1000), max_intensity);
269
270 out_assign_max:
271 dev_info(rt->dev, "max intensity %d/%d = %d mA\n",
272 max_intensity, hw_max, max_ma);
273 *max_intensity_setting = max_intensity;
274 }
275
rt8515_probe(struct platform_device * pdev)276 static int rt8515_probe(struct platform_device *pdev)
277 {
278 struct device *dev = &pdev->dev;
279 struct fwnode_handle *child;
280 struct rt8515 *rt;
281 struct led_classdev *led;
282 struct led_classdev_flash *fled;
283 struct led_init_data init_data = {};
284 struct v4l2_flash_config v4l2_sd_cfg = {};
285 int ret;
286
287 rt = devm_kzalloc(dev, sizeof(*rt), GFP_KERNEL);
288 if (!rt)
289 return -ENOMEM;
290
291 rt->dev = dev;
292 fled = &rt->fled;
293 led = &fled->led_cdev;
294
295 /* ENF - Enable Flash line */
296 rt->enable_flash = devm_gpiod_get(dev, "enf", GPIOD_OUT_LOW);
297 if (IS_ERR(rt->enable_flash))
298 return dev_err_probe(dev, PTR_ERR(rt->enable_flash),
299 "cannot get ENF (enable flash) GPIO\n");
300
301 /* ENT - Enable Torch line */
302 rt->enable_torch = devm_gpiod_get(dev, "ent", GPIOD_OUT_LOW);
303 if (IS_ERR(rt->enable_torch))
304 return dev_err_probe(dev, PTR_ERR(rt->enable_torch),
305 "cannot get ENT (enable torch) GPIO\n");
306
307 child = fwnode_get_next_available_child_node(dev->fwnode, NULL);
308 if (!child) {
309 dev_err(dev,
310 "No fwnode child node found for connected LED.\n");
311 return -EINVAL;
312 }
313 init_data.fwnode = child;
314
315 rt8515_determine_max_intensity(rt, child, "richtek,rfs-ohms",
316 "flash-max-microamp",
317 RT8515_FLASH_MAX,
318 &rt->flash_max_intensity);
319 rt8515_determine_max_intensity(rt, child, "richtek,rts-ohms",
320 "led-max-microamp",
321 RT8515_TORCH_MAX,
322 &rt->torch_max_intensity);
323
324 ret = fwnode_property_read_u32(child, "flash-max-timeout-us",
325 &rt->max_timeout);
326 if (ret) {
327 rt->max_timeout = RT8515_MAX_TIMEOUT_US;
328 dev_warn(dev,
329 "flash-max-timeout-us property missing\n");
330 }
331 timer_setup(&rt->powerdown_timer, rt8515_powerdown_timer, 0);
332 rt8515_init_flash_timeout(rt);
333
334 fled->ops = &rt8515_flash_ops;
335
336 led->max_brightness = rt->torch_max_intensity;
337 led->brightness_set_blocking = rt8515_led_brightness_set;
338 led->flags |= LED_CORE_SUSPENDRESUME | LED_DEV_CAP_FLASH;
339
340 mutex_init(&rt->lock);
341
342 platform_set_drvdata(pdev, rt);
343
344 ret = devm_led_classdev_flash_register_ext(dev, fled, &init_data);
345 if (ret) {
346 fwnode_handle_put(child);
347 mutex_destroy(&rt->lock);
348 dev_err(dev, "can't register LED %s\n", led->name);
349 return ret;
350 }
351
352 rt8515_init_v4l2_flash_config(rt, &v4l2_sd_cfg);
353
354 /* Create a V4L2 Flash device if V4L2 flash is enabled */
355 rt->v4l2_flash = v4l2_flash_init(dev, child, fled, NULL, &v4l2_sd_cfg);
356 if (IS_ERR(rt->v4l2_flash)) {
357 ret = PTR_ERR(rt->v4l2_flash);
358 dev_err(dev, "failed to register V4L2 flash device (%d)\n",
359 ret);
360 /*
361 * Continue without the V4L2 flash
362 * (we still have the classdev)
363 */
364 }
365
366 fwnode_handle_put(child);
367 return 0;
368 }
369
rt8515_remove(struct platform_device * pdev)370 static int rt8515_remove(struct platform_device *pdev)
371 {
372 struct rt8515 *rt = platform_get_drvdata(pdev);
373
374 rt8515_v4l2_flash_release(rt);
375 del_timer_sync(&rt->powerdown_timer);
376 mutex_destroy(&rt->lock);
377
378 return 0;
379 }
380
381 static const struct of_device_id rt8515_match[] = {
382 { .compatible = "richtek,rt8515", },
383 { /* sentinel */ }
384 };
385 MODULE_DEVICE_TABLE(of, rt8515_match);
386
387 static struct platform_driver rt8515_driver = {
388 .driver = {
389 .name = "rt8515",
390 .of_match_table = rt8515_match,
391 },
392 .probe = rt8515_probe,
393 .remove = rt8515_remove,
394 };
395 module_platform_driver(rt8515_driver);
396
397 MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
398 MODULE_DESCRIPTION("Richtek RT8515 LED driver");
399 MODULE_LICENSE("GPL");
400