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