xref: /openbmc/linux/drivers/leds/leds-lp3944.c (revision d9ff8a8e)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * leds-lp3944.c - driver for National Semiconductor LP3944 Funlight Chip
4  *
5  * Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it>
6  */
7 
8 /*
9  * I2C driver for National Semiconductor LP3944 Funlight Chip
10  * http://www.national.com/pf/LP/LP3944.html
11  *
12  * This helper chip can drive up to 8 leds, with two programmable DIM modes;
13  * it could even be used as a gpio expander but this driver assumes it is used
14  * as a led controller.
15  *
16  * The DIM modes are used to set _blink_ patterns for leds, the pattern is
17  * specified supplying two parameters:
18  *   - period: from 0s to 1.6s
19  *   - duty cycle: percentage of the period the led is on, from 0 to 100
20  *
21  * LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
22  * leds, the camera flash light and the displays backlights.
23  */
24 
25 #include <linux/module.h>
26 #include <linux/i2c.h>
27 #include <linux/slab.h>
28 #include <linux/leds.h>
29 #include <linux/mutex.h>
30 #include <linux/leds-lp3944.h>
31 
32 /* Read Only Registers */
33 #define LP3944_REG_INPUT1     0x00 /* LEDs 0-7 InputRegister (Read Only) */
34 #define LP3944_REG_REGISTER1  0x01 /* None (Read Only) */
35 
36 #define LP3944_REG_PSC0       0x02 /* Frequency Prescaler 0 (R/W) */
37 #define LP3944_REG_PWM0       0x03 /* PWM Register 0 (R/W) */
38 #define LP3944_REG_PSC1       0x04 /* Frequency Prescaler 1 (R/W) */
39 #define LP3944_REG_PWM1       0x05 /* PWM Register 1 (R/W) */
40 #define LP3944_REG_LS0        0x06 /* LEDs 0-3 Selector (R/W) */
41 #define LP3944_REG_LS1        0x07 /* LEDs 4-7 Selector (R/W) */
42 
43 /* These registers are not used to control leds in LP3944, they can store
44  * arbitrary values which the chip will ignore.
45  */
46 #define LP3944_REG_REGISTER8  0x08
47 #define LP3944_REG_REGISTER9  0x09
48 
49 #define LP3944_DIM0 0
50 #define LP3944_DIM1 1
51 
52 /* period in ms */
53 #define LP3944_PERIOD_MIN 0
54 #define LP3944_PERIOD_MAX 1600
55 
56 /* duty cycle is a percentage */
57 #define LP3944_DUTY_CYCLE_MIN 0
58 #define LP3944_DUTY_CYCLE_MAX 100
59 
60 #define ldev_to_led(c)       container_of(c, struct lp3944_led_data, ldev)
61 
62 /* Saved data */
63 struct lp3944_led_data {
64 	u8 id;
65 	enum lp3944_type type;
66 	struct led_classdev ldev;
67 	struct i2c_client *client;
68 };
69 
70 struct lp3944_data {
71 	struct mutex lock;
72 	struct i2c_client *client;
73 	struct lp3944_led_data leds[LP3944_LEDS_MAX];
74 };
75 
lp3944_reg_read(struct i2c_client * client,u8 reg,u8 * value)76 static int lp3944_reg_read(struct i2c_client *client, u8 reg, u8 *value)
77 {
78 	int tmp;
79 
80 	tmp = i2c_smbus_read_byte_data(client, reg);
81 	if (tmp < 0)
82 		return tmp;
83 
84 	*value = tmp;
85 
86 	return 0;
87 }
88 
lp3944_reg_write(struct i2c_client * client,u8 reg,u8 value)89 static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value)
90 {
91 	return i2c_smbus_write_byte_data(client, reg, value);
92 }
93 
94 /**
95  * lp3944_dim_set_period() - Set the period for DIM status
96  *
97  * @client: the i2c client
98  * @dim: either LP3944_DIM0 or LP3944_DIM1
99  * @period: period of a blink, that is a on/off cycle, expressed in ms.
100  */
lp3944_dim_set_period(struct i2c_client * client,u8 dim,u16 period)101 static int lp3944_dim_set_period(struct i2c_client *client, u8 dim, u16 period)
102 {
103 	u8 psc_reg;
104 	u8 psc_value;
105 	int err;
106 
107 	if (dim == LP3944_DIM0)
108 		psc_reg = LP3944_REG_PSC0;
109 	else if (dim == LP3944_DIM1)
110 		psc_reg = LP3944_REG_PSC1;
111 	else
112 		return -EINVAL;
113 
114 	/* Convert period to Prescaler value */
115 	if (period > LP3944_PERIOD_MAX)
116 		return -EINVAL;
117 
118 	psc_value = (period * 255) / LP3944_PERIOD_MAX;
119 
120 	err = lp3944_reg_write(client, psc_reg, psc_value);
121 
122 	return err;
123 }
124 
125 /**
126  * lp3944_dim_set_dutycycle - Set the duty cycle for DIM status
127  *
128  * @client: the i2c client
129  * @dim: either LP3944_DIM0 or LP3944_DIM1
130  * @duty_cycle: percentage of a period during which a led is ON
131  */
lp3944_dim_set_dutycycle(struct i2c_client * client,u8 dim,u8 duty_cycle)132 static int lp3944_dim_set_dutycycle(struct i2c_client *client, u8 dim,
133 				    u8 duty_cycle)
134 {
135 	u8 pwm_reg;
136 	u8 pwm_value;
137 	int err;
138 
139 	if (dim == LP3944_DIM0)
140 		pwm_reg = LP3944_REG_PWM0;
141 	else if (dim == LP3944_DIM1)
142 		pwm_reg = LP3944_REG_PWM1;
143 	else
144 		return -EINVAL;
145 
146 	/* Convert duty cycle to PWM value */
147 	if (duty_cycle > LP3944_DUTY_CYCLE_MAX)
148 		return -EINVAL;
149 
150 	pwm_value = (duty_cycle * 255) / LP3944_DUTY_CYCLE_MAX;
151 
152 	err = lp3944_reg_write(client, pwm_reg, pwm_value);
153 
154 	return err;
155 }
156 
157 /**
158  * lp3944_led_set() - Set the led status
159  *
160  * @led: a lp3944_led_data structure
161  * @status: one of LP3944_LED_STATUS_OFF
162  *                 LP3944_LED_STATUS_ON
163  *                 LP3944_LED_STATUS_DIM0
164  *                 LP3944_LED_STATUS_DIM1
165  */
lp3944_led_set(struct lp3944_led_data * led,u8 status)166 static int lp3944_led_set(struct lp3944_led_data *led, u8 status)
167 {
168 	struct lp3944_data *data = i2c_get_clientdata(led->client);
169 	u8 id = led->id;
170 	u8 reg;
171 	u8 val = 0;
172 	int err;
173 
174 	dev_dbg(&led->client->dev, "%s: %s, status before normalization:%d\n",
175 		__func__, led->ldev.name, status);
176 
177 	switch (id) {
178 	case LP3944_LED0:
179 	case LP3944_LED1:
180 	case LP3944_LED2:
181 	case LP3944_LED3:
182 		reg = LP3944_REG_LS0;
183 		break;
184 	case LP3944_LED4:
185 	case LP3944_LED5:
186 	case LP3944_LED6:
187 	case LP3944_LED7:
188 		id -= LP3944_LED4;
189 		reg = LP3944_REG_LS1;
190 		break;
191 	default:
192 		return -EINVAL;
193 	}
194 
195 	if (status > LP3944_LED_STATUS_DIM1)
196 		return -EINVAL;
197 
198 	/*
199 	 * Invert status only when it's < 2 (i.e. 0 or 1) which means it's
200 	 * controlling the on/off state directly.
201 	 * When, instead, status is >= 2 don't invert it because it would mean
202 	 * to mess with the hardware blinking mode.
203 	 */
204 	if (led->type == LP3944_LED_TYPE_LED_INVERTED && status < 2)
205 		status = 1 - status;
206 
207 	mutex_lock(&data->lock);
208 	lp3944_reg_read(led->client, reg, &val);
209 
210 	val &= ~(LP3944_LED_STATUS_MASK << (id << 1));
211 	val |= (status << (id << 1));
212 
213 	dev_dbg(&led->client->dev, "%s: %s, reg:%d id:%d status:%d val:%#x\n",
214 		__func__, led->ldev.name, reg, id, status, val);
215 
216 	/* set led status */
217 	err = lp3944_reg_write(led->client, reg, val);
218 	mutex_unlock(&data->lock);
219 
220 	return err;
221 }
222 
lp3944_led_set_blink(struct led_classdev * led_cdev,unsigned long * delay_on,unsigned long * delay_off)223 static int lp3944_led_set_blink(struct led_classdev *led_cdev,
224 				unsigned long *delay_on,
225 				unsigned long *delay_off)
226 {
227 	struct lp3944_led_data *led = ldev_to_led(led_cdev);
228 	u16 period;
229 	u8 duty_cycle;
230 	int err;
231 
232 	/* units are in ms */
233 	if (*delay_on + *delay_off > LP3944_PERIOD_MAX)
234 		return -EINVAL;
235 
236 	if (*delay_on == 0 && *delay_off == 0) {
237 		/* Special case: the leds subsystem requires a default user
238 		 * friendly blink pattern for the LED.  Let's blink the led
239 		 * slowly (1Hz).
240 		 */
241 		*delay_on = 500;
242 		*delay_off = 500;
243 	}
244 
245 	period = (*delay_on) + (*delay_off);
246 
247 	/* duty_cycle is the percentage of period during which the led is ON */
248 	duty_cycle = 100 * (*delay_on) / period;
249 
250 	/* invert duty cycle for inverted leds, this has the same effect of
251 	 * swapping delay_on and delay_off
252 	 */
253 	if (led->type == LP3944_LED_TYPE_LED_INVERTED)
254 		duty_cycle = 100 - duty_cycle;
255 
256 	/* NOTE: using always the first DIM mode, this means that all leds
257 	 * will have the same blinking pattern.
258 	 *
259 	 * We could find a way later to have two leds blinking in hardware
260 	 * with different patterns at the same time, falling back to software
261 	 * control for the other ones.
262 	 */
263 	err = lp3944_dim_set_period(led->client, LP3944_DIM0, period);
264 	if (err)
265 		return err;
266 
267 	err = lp3944_dim_set_dutycycle(led->client, LP3944_DIM0, duty_cycle);
268 	if (err)
269 		return err;
270 
271 	dev_dbg(&led->client->dev, "%s: OK hardware accelerated blink!\n",
272 		__func__);
273 
274 	lp3944_led_set(led, LP3944_LED_STATUS_DIM0);
275 
276 	return 0;
277 }
278 
lp3944_led_set_brightness(struct led_classdev * led_cdev,enum led_brightness brightness)279 static int lp3944_led_set_brightness(struct led_classdev *led_cdev,
280 				      enum led_brightness brightness)
281 {
282 	struct lp3944_led_data *led = ldev_to_led(led_cdev);
283 
284 	dev_dbg(&led->client->dev, "%s: %s, %d\n",
285 		__func__, led_cdev->name, brightness);
286 
287 	return lp3944_led_set(led, !!brightness);
288 }
289 
lp3944_configure(struct i2c_client * client,struct lp3944_data * data,struct lp3944_platform_data * pdata)290 static int lp3944_configure(struct i2c_client *client,
291 			    struct lp3944_data *data,
292 			    struct lp3944_platform_data *pdata)
293 {
294 	int i, err = 0;
295 
296 	for (i = 0; i < pdata->leds_size; i++) {
297 		struct lp3944_led *pled = &pdata->leds[i];
298 		struct lp3944_led_data *led = &data->leds[i];
299 		led->client = client;
300 		led->id = i;
301 
302 		switch (pled->type) {
303 
304 		case LP3944_LED_TYPE_LED:
305 		case LP3944_LED_TYPE_LED_INVERTED:
306 			led->type = pled->type;
307 			led->ldev.name = pled->name;
308 			led->ldev.max_brightness = 1;
309 			led->ldev.brightness_set_blocking =
310 						lp3944_led_set_brightness;
311 			led->ldev.blink_set = lp3944_led_set_blink;
312 			led->ldev.flags = LED_CORE_SUSPENDRESUME;
313 
314 			err = led_classdev_register(&client->dev, &led->ldev);
315 			if (err < 0) {
316 				dev_err(&client->dev,
317 					"couldn't register LED %s\n",
318 					led->ldev.name);
319 				goto exit;
320 			}
321 
322 			/* to expose the default value to userspace */
323 			led->ldev.brightness =
324 					(enum led_brightness) pled->status;
325 
326 			/* Set the default led status */
327 			err = lp3944_led_set(led, pled->status);
328 			if (err < 0) {
329 				dev_err(&client->dev,
330 					"%s couldn't set STATUS %d\n",
331 					led->ldev.name, pled->status);
332 				goto exit;
333 			}
334 			break;
335 
336 		case LP3944_LED_TYPE_NONE:
337 		default:
338 			break;
339 
340 		}
341 	}
342 	return 0;
343 
344 exit:
345 	if (i > 0)
346 		for (i = i - 1; i >= 0; i--)
347 			switch (pdata->leds[i].type) {
348 
349 			case LP3944_LED_TYPE_LED:
350 			case LP3944_LED_TYPE_LED_INVERTED:
351 				led_classdev_unregister(&data->leds[i].ldev);
352 				break;
353 
354 			case LP3944_LED_TYPE_NONE:
355 			default:
356 				break;
357 			}
358 
359 	return err;
360 }
361 
lp3944_probe(struct i2c_client * client)362 static int lp3944_probe(struct i2c_client *client)
363 {
364 	struct lp3944_platform_data *lp3944_pdata =
365 			dev_get_platdata(&client->dev);
366 	struct lp3944_data *data;
367 	int err;
368 
369 	if (lp3944_pdata == NULL) {
370 		dev_err(&client->dev, "no platform data\n");
371 		return -EINVAL;
372 	}
373 
374 	/* Let's see whether this adapter can support what we need. */
375 	if (!i2c_check_functionality(client->adapter,
376 				I2C_FUNC_SMBUS_BYTE_DATA)) {
377 		dev_err(&client->dev, "insufficient functionality!\n");
378 		return -ENODEV;
379 	}
380 
381 	data = devm_kzalloc(&client->dev, sizeof(struct lp3944_data),
382 			GFP_KERNEL);
383 	if (!data)
384 		return -ENOMEM;
385 
386 	data->client = client;
387 	i2c_set_clientdata(client, data);
388 
389 	mutex_init(&data->lock);
390 
391 	err = lp3944_configure(client, data, lp3944_pdata);
392 	if (err < 0)
393 		return err;
394 
395 	dev_info(&client->dev, "lp3944 enabled\n");
396 	return 0;
397 }
398 
lp3944_remove(struct i2c_client * client)399 static void lp3944_remove(struct i2c_client *client)
400 {
401 	struct lp3944_platform_data *pdata = dev_get_platdata(&client->dev);
402 	struct lp3944_data *data = i2c_get_clientdata(client);
403 	int i;
404 
405 	for (i = 0; i < pdata->leds_size; i++)
406 		switch (data->leds[i].type) {
407 		case LP3944_LED_TYPE_LED:
408 		case LP3944_LED_TYPE_LED_INVERTED:
409 			led_classdev_unregister(&data->leds[i].ldev);
410 			break;
411 
412 		case LP3944_LED_TYPE_NONE:
413 		default:
414 			break;
415 		}
416 }
417 
418 /* lp3944 i2c driver struct */
419 static const struct i2c_device_id lp3944_id[] = {
420 	{"lp3944", 0},
421 	{}
422 };
423 
424 MODULE_DEVICE_TABLE(i2c, lp3944_id);
425 
426 static struct i2c_driver lp3944_driver = {
427 	.driver   = {
428 		   .name = "lp3944",
429 	},
430 	.probe    = lp3944_probe,
431 	.remove   = lp3944_remove,
432 	.id_table = lp3944_id,
433 };
434 
435 module_i2c_driver(lp3944_driver);
436 
437 MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
438 MODULE_DESCRIPTION("LP3944 Fun Light Chip");
439 MODULE_LICENSE("GPL");
440