summaryrefslogtreecommitdiffstats
path: root/drivers/leds/leds-lp3944.c
blob: 0c4386e656c162fcea462743d618638037094124 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
/*
 * leds-lp3944.c - driver for National Semiconductor LP3944 Funlight Chip
 *
 * Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

/*
 * I2C driver for National Semiconductor LP3944 Funlight Chip
 * http://www.national.com/pf/LP/LP3944.html
 *
 * This helper chip can drive up to 8 leds, with two programmable DIM modes;
 * it could even be used as a gpio expander but this driver assumes it is used
 * as a led controller.
 *
 * The DIM modes are used to set _blink_ patterns for leds, the pattern is
 * specified supplying two parameters:
 *   - period: from 0s to 1.6s
 *   - duty cycle: percentage of the period the led is on, from 0 to 100
 *
 * LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
 * leds, the camera flash light and the displays backlights.
 */

#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/leds.h>
#include <linux/mutex.h>
#include <linux/workqueue.h>
#include <linux/leds-lp3944.h>

/* Read Only Registers */
#define LP3944_REG_INPUT1     0x00 /* LEDs 0-7 InputRegister (Read Only) */
#define LP3944_REG_REGISTER1  0x01 /* None (Read Only) */

#define LP3944_REG_PSC0       0x02 /* Frequency Prescaler 0 (R/W) */
#define LP3944_REG_PWM0       0x03 /* PWM Register 0 (R/W) */
#define LP3944_REG_PSC1       0x04 /* Frequency Prescaler 1 (R/W) */
#define LP3944_REG_PWM1       0x05 /* PWM Register 1 (R/W) */
#define LP3944_REG_LS0        0x06 /* LEDs 0-3 Selector (R/W) */
#define LP3944_REG_LS1        0x07 /* LEDs 4-7 Selector (R/W) */

/* These registers are not used to control leds in LP3944, they can store
 * arbitrary values which the chip will ignore.
 */
#define LP3944_REG_REGISTER8  0x08
#define LP3944_REG_REGISTER9  0x09

#define LP3944_DIM0 0
#define LP3944_DIM1 1

/* period in ms */
#define LP3944_PERIOD_MIN 0
#define LP3944_PERIOD_MAX 1600

/* duty cycle is a percentage */
#define LP3944_DUTY_CYCLE_MIN 0
#define LP3944_DUTY_CYCLE_MAX 100

#define ldev_to_led(c)       container_of(c, struct lp3944_led_data, ldev)

/* Saved data */
struct lp3944_led_data {
	u8 id;
	enum lp3944_type type;
	enum lp3944_status status;
	struct led_classdev ldev;
	struct i2c_client *client;
	struct work_struct work;
};

struct lp3944_data {
	struct mutex lock;
	struct i2c_client *client;
	struct lp3944_led_data leds[LP3944_LEDS_MAX];
};

static int lp3944_reg_read(struct i2c_client *client, u8 reg, u8 *value)
{
	int tmp;

	tmp = i2c_smbus_read_byte_data(client, reg);
	if (tmp < 0)
		return tmp;

	*value = tmp;

	return 0;
}

static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value)
{
	return i2c_smbus_write_byte_data(client, reg, value);
}

/**
 * Set the period for DIM status
 *
 * @client: the i2c client
 * @dim: either LP3944_DIM0 or LP3944_DIM1
 * @period: period of a blink, that is a on/off cycle, expressed in ms.
 */
static int lp3944_dim_set_period(struct i2c_client *client, u8 dim, u16 period)
{
	u8 psc_reg;
	u8 psc_value;
	int err;

	if (dim == LP3944_DIM0)
		psc_reg = LP3944_REG_PSC0;
	else if (dim == LP3944_DIM1)
		psc_reg = LP3944_REG_PSC1;
	else
		return -EINVAL;

	/* Convert period to Prescaler value */
	if (period > LP3944_PERIOD_MAX)
		return -EINVAL;

	psc_value = (period * 255) / LP3944_PERIOD_MAX;

	err = lp3944_reg_write(client, psc_reg, psc_value);

	return err;
}

/**
 * Set the duty cycle for DIM status
 *
 * @client: the i2c client
 * @dim: either LP3944_DIM0 or LP3944_DIM1
 * @duty_cycle: percentage of a period during which a led is ON
 */
static int lp3944_dim_set_dutycycle(struct i2c_client *client, u8 dim,
				    u8 duty_cycle)
{
	u8 pwm_reg;
	u8 pwm_value;
	int err;

	if (dim == LP3944_DIM0)
		pwm_reg = LP3944_REG_PWM0;
	else if (dim == LP3944_DIM1)
		pwm_reg = LP3944_REG_PWM1;
	else
		return -EINVAL;

	/* Convert duty cycle to PWM value */
	if (duty_cycle > LP3944_DUTY_CYCLE_MAX)
		return -EINVAL;

	pwm_value = (duty_cycle * 255) / LP3944_DUTY_CYCLE_MAX;

	err = lp3944_reg_write(client, pwm_reg, pwm_value);

	return err;
}

/**
 * Set the led status
 *
 * @led: a lp3944_led_data structure
 * @status: one of LP3944_LED_STATUS_OFF
 *                 LP3944_LED_STATUS_ON
 *                 LP3944_LED_STATUS_DIM0
 *                 LP3944_LED_STATUS_DIM1
 */
static int lp3944_led_set(struct lp3944_led_data *led, u8 status)
{
	struct lp3944_data *data = i2c_get_clientdata(led->client);
	u8 id = led->id;
	u8 reg;
	u8 val = 0;
	int err;

	dev_dbg(&led->client->dev, "%s: %s, status before normalization:%d\n",
		__func__, led->ldev.name, status);

	switch (id) {
	case LP3944_LED0:
	case LP3944_LED1:
	case LP3944_LED2:
	case LP3944_LED3:
		reg = LP3944_REG_LS0;
		break;
	case LP3944_LED4:
	case LP3944_LED5:
	case LP3944_LED6:
	case LP3944_LED7:
		id -= LP3944_LED4;
		reg = LP3944_REG_LS1;
		break;
	default:
		return -EINVAL;
	}

	if (status > LP3944_LED_STATUS_DIM1)
		return -EINVAL;

	/* invert only 0 and 1, leave unchanged the other values,
	 * remember we are abusing status to set blink patterns
	 */
	if (led->type == LP3944_LED_TYPE_LED_INVERTED && status < 2)
		status = 1 - status;

	mutex_lock(&data->lock);
	lp3944_reg_read(led->client, reg, &val);

	val &= ~(LP3944_LED_STATUS_MASK << (id << 1));
	val |= (status << (id << 1));

	dev_dbg(&led->client->dev, "%s: %s, reg:%d id:%d status:%d val:%#x\n",
		__func__, led->ldev.name, reg, id, status, val);

	/* set led status */
	err = lp3944_reg_write(led->client, reg, val);
	mutex_unlock(&data->lock);

	return err;
}

static int lp3944_led_set_blink(struct led_classdev *led_cdev,
				unsigned long *delay_on,
				unsigned long *delay_off)
{
	struct lp3944_led_data *led = ldev_to_led(led_cdev);
	u16 period;
	u8 duty_cycle;
	int err;

	/* units are in ms */
	if (*delay_on + *delay_off > LP3944_PERIOD_MAX)
		return -EINVAL;

	if (*delay_on == 0 && *delay_off == 0) {
		/* Special case: the leds subsystem requires a default user
		 * friendly blink pattern for the LED.  Let's blink the led
		 * slowly (1Hz).
		 */
		*delay_on = 500;
		*delay_off = 500;
	}

	period = (*delay_on) + (*delay_off);

	/* duty_cycle is the percentage of period during which the led is ON */
	duty_cycle = 100 * (*delay_on) / period;

	/* invert duty cycle for inverted leds, this has the same effect of
	 * swapping delay_on and delay_off
	 */
	if (led->type == LP3944_LED_TYPE_LED_INVERTED)
		duty_cycle = 100 - duty_cycle;

	/* NOTE: using always the first DIM mode, this means that all leds
	 * will have the same blinking pattern.
	 *
	 * We could find a way later to have two leds blinking in hardware
	 * with different patterns at the same time, falling back to software
	 * control for the other ones.
	 */
	err = lp3944_dim_set_period(led->client, LP3944_DIM0, period);
	if (err)
		return err;

	err = lp3944_dim_set_dutycycle(led->client, LP3944_DIM0, duty_cycle);
	if (err)
		return err;

	dev_dbg(&led->client->dev, "%s: OK hardware accelerated blink!\n",
		__func__);

	led->status = LP3944_LED_STATUS_DIM0;
	schedule_work(&led->work);

	return 0;
}

static void lp3944_led_set_brightness(struct led_classdev *led_cdev,
				      enum led_brightness brightness)
{
	struct lp3944_led_data *led = ldev_to_led(led_cdev);

	dev_dbg(&led->client->dev, "%s: %s, %d\n",
		__func__, led_cdev->name, brightness);

	led->status = brightness;
	schedule_work(&led->work);
}

static void lp3944_led_work(struct work_struct *work)
{
	struct lp3944_led_data *led;

	led = container_of(work, struct lp3944_led_data, work);
	lp3944_led_set(led, led->status);
}

static int lp3944_configure(struct i2c_client *client,
			    struct lp3944_data *data,
			    struct lp3944_platform_data *pdata)
{
	int i, err = 0;

	for (i = 0; i < pdata->leds_size; i++) {
		struct lp3944_led *pled = &pdata->leds[i];
		struct lp3944_led_data *led = &data->leds[i];
		led->client = client;
		led->id = i;

		switch (pled->type) {

		case LP3944_LED_TYPE_LED:
		case LP3944_LED_TYPE_LED_INVERTED:
			led->type = pled->type;
			led->status = pled->status;
			led->ldev.name = pled->name;
			led->ldev.max_brightness = 1;
			led->ldev.brightness_set = lp3944_led_set_brightness;
			led->ldev.blink_set = lp3944_led_set_blink;
			led->ldev.flags = LED_CORE_SUSPENDRESUME;

			INIT_WORK(&led->work, lp3944_led_work);
			err = led_classdev_register(&client->dev, &led->ldev);
			if (err < 0) {
				dev_err(&client->dev,
					"couldn't register LED %s\n",
					led->ldev.name);
				goto exit;
			}

			/* to expose the default value to userspace */
			led->ldev.brightness = led->status;

			/* Set the default led status */
			err = lp3944_led_set(led, led->status);
			if (err < 0) {
				dev_err(&client->dev,
					"%s couldn't set STATUS %d\n",
					led->ldev.name, led->status);
				goto exit;
			}
			break;

		case LP3944_LED_TYPE_NONE:
		default:
			break;

		}
	}
	return 0;

exit:
	if (i > 0)
		for (i = i - 1; i >= 0; i--)
			switch (pdata->leds[i].type) {

			case LP3944_LED_TYPE_LED:
			case LP3944_LED_TYPE_LED_INVERTED:
				led_classdev_unregister(&data->leds[i].ldev);
				cancel_work_sync(&data->leds[i].work);
				break;

			case LP3944_LED_TYPE_NONE:
			default:
				break;
			}

	return err;
}

static int lp3944_probe(struct i2c_client *client,
				  const struct i2c_device_id *id)
{
	struct lp3944_platform_data *lp3944_pdata = client->dev.platform_data;
	struct lp3944_data *data;
	int err;

	if (lp3944_pdata == NULL) {
		dev_err(&client->dev, "no platform data\n");
		return -EINVAL;
	}

	/* Let's see whether this adapter can support what we need. */
	if (!i2c_check_functionality(client->adapter,
				I2C_FUNC_SMBUS_BYTE_DATA)) {
		dev_err(&client->dev, "insufficient functionality!\n");
		return -ENODEV;
	}

	data = devm_kzalloc(&client->dev, sizeof(struct lp3944_data),
			GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->client = client;
	i2c_set_clientdata(client, data);

	mutex_init(&data->lock);

	err = lp3944_configure(client, data, lp3944_pdata);
	if (err < 0)
		return err;

	dev_info(&client->dev, "lp3944 enabled\n");
	return 0;
}

static int lp3944_remove(struct i2c_client *client)
{
	struct lp3944_platform_data *pdata = client->dev.platform_data;
	struct lp3944_data *data = i2c_get_clientdata(client);
	int i;

	for (i = 0; i < pdata->leds_size; i++)
		switch (data->leds[i].type) {
		case LP3944_LED_TYPE_LED:
		case LP3944_LED_TYPE_LED_INVERTED:
			led_classdev_unregister(&data->leds[i].ldev);
			cancel_work_sync(&data->leds[i].work);
			break;

		case LP3944_LED_TYPE_NONE:
		default:
			break;
		}

	return 0;
}

/* lp3944 i2c driver struct */
static const struct i2c_device_id lp3944_id[] = {
	{"lp3944", 0},
	{}
};

MODULE_DEVICE_TABLE(i2c, lp3944_id);

static struct i2c_driver lp3944_driver = {
	.driver   = {
		   .name = "lp3944",
	},
	.probe    = lp3944_probe,
	.remove   = lp3944_remove,
	.id_table = lp3944_id,
};

module_i2c_driver(lp3944_driver);

MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
MODULE_DESCRIPTION("LP3944 Fun Light Chip");
MODULE_LICENSE("GPL");
OpenPOWER on IntegriCloud