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
47struct 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
61static struct rt8515 *to_rt8515(struct led_classdev_flash *fled)
62{
63	return container_of(fled, struct rt8515, fled);
64}
65
66static 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
72static 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 */
90static 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
114static 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
143static 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
153static 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
160static 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
166static 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
174static 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 */
193static 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
214static void rt8515_v4l2_flash_release(struct rt8515 *rt)
215{
216	v4l2_flash_release(rt->v4l2_flash);
217}
218
219#else
220static void rt8515_init_v4l2_flash_config(struct rt8515 *rt,
221					  struct v4l2_flash_config *v4l2_sd_cfg)
222{
223}
224
225static void rt8515_v4l2_flash_release(struct rt8515 *rt)
226{
227}
228#endif
229
230static 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
270out_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
276static 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
370static void 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
379static const struct of_device_id rt8515_match[] = {
380	{ .compatible = "richtek,rt8515", },
381	{ /* sentinel */ }
382};
383MODULE_DEVICE_TABLE(of, rt8515_match);
384
385static struct platform_driver rt8515_driver = {
386	.driver = {
387		.name  = "rt8515",
388		.of_match_table = rt8515_match,
389	},
390	.probe  = rt8515_probe,
391	.remove_new = rt8515_remove,
392};
393module_platform_driver(rt8515_driver);
394
395MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
396MODULE_DESCRIPTION("Richtek RT8515 LED driver");
397MODULE_LICENSE("GPL");
398