1/*
2 * leds-lp3944.c - driver for National Semiconductor LP3944 Funlight Chip
3 *
4 * Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 */
11
12/*
13 * I2C driver for National Semiconductor LP3944 Funlight Chip
14 * http://www.national.com/pf/LP/LP3944.html
15 *
16 * This helper chip can drive up to 8 leds, with two programmable DIM modes;
17 * it could even be used as a gpio expander but this driver assumes it is used
18 * as a led controller.
19 *
20 * The DIM modes are used to set _blink_ patterns for leds, the pattern is
21 * specified supplying two parameters:
22 *   - period: from 0s to 1.6s
23 *   - duty cycle: percentage of the period the led is on, from 0 to 100
24 *
25 * LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
26 * leds, the camera flash light and the displays backlights.
27 */
28
29#include <linux/module.h>
30#include <linux/i2c.h>
31#include <linux/slab.h>
32#include <linux/leds.h>
33#include <linux/mutex.h>
34#include <linux/workqueue.h>
35#include <linux/leds-lp3944.h>
36
37/* Read Only Registers */
38#define LP3944_REG_INPUT1     0x00 /* LEDs 0-7 InputRegister (Read Only) */
39#define LP3944_REG_REGISTER1  0x01 /* None (Read Only) */
40
41#define LP3944_REG_PSC0       0x02 /* Frequency Prescaler 0 (R/W) */
42#define LP3944_REG_PWM0       0x03 /* PWM Register 0 (R/W) */
43#define LP3944_REG_PSC1       0x04 /* Frequency Prescaler 1 (R/W) */
44#define LP3944_REG_PWM1       0x05 /* PWM Register 1 (R/W) */
45#define LP3944_REG_LS0        0x06 /* LEDs 0-3 Selector (R/W) */
46#define LP3944_REG_LS1        0x07 /* LEDs 4-7 Selector (R/W) */
47
48/* These registers are not used to control leds in LP3944, they can store
49 * arbitrary values which the chip will ignore.
50 */
51#define LP3944_REG_REGISTER8  0x08
52#define LP3944_REG_REGISTER9  0x09
53
54#define LP3944_DIM0 0
55#define LP3944_DIM1 1
56
57/* period in ms */
58#define LP3944_PERIOD_MIN 0
59#define LP3944_PERIOD_MAX 1600
60
61/* duty cycle is a percentage */
62#define LP3944_DUTY_CYCLE_MIN 0
63#define LP3944_DUTY_CYCLE_MAX 100
64
65#define ldev_to_led(c)       container_of(c, struct lp3944_led_data, ldev)
66
67/* Saved data */
68struct lp3944_led_data {
69	u8 id;
70	enum lp3944_type type;
71	enum lp3944_status status;
72	struct led_classdev ldev;
73	struct i2c_client *client;
74	struct work_struct work;
75};
76
77struct lp3944_data {
78	struct mutex lock;
79	struct i2c_client *client;
80	struct lp3944_led_data leds[LP3944_LEDS_MAX];
81};
82
83static int lp3944_reg_read(struct i2c_client *client, u8 reg, u8 *value)
84{
85	int tmp;
86
87	tmp = i2c_smbus_read_byte_data(client, reg);
88	if (tmp < 0)
89		return tmp;
90
91	*value = tmp;
92
93	return 0;
94}
95
96static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value)
97{
98	return i2c_smbus_write_byte_data(client, reg, value);
99}
100
101/**
102 * Set the period for DIM status
103 *
104 * @client: the i2c client
105 * @dim: either LP3944_DIM0 or LP3944_DIM1
106 * @period: period of a blink, that is a on/off cycle, expressed in ms.
107 */
108static int lp3944_dim_set_period(struct i2c_client *client, u8 dim, u16 period)
109{
110	u8 psc_reg;
111	u8 psc_value;
112	int err;
113
114	if (dim == LP3944_DIM0)
115		psc_reg = LP3944_REG_PSC0;
116	else if (dim == LP3944_DIM1)
117		psc_reg = LP3944_REG_PSC1;
118	else
119		return -EINVAL;
120
121	/* Convert period to Prescaler value */
122	if (period > LP3944_PERIOD_MAX)
123		return -EINVAL;
124
125	psc_value = (period * 255) / LP3944_PERIOD_MAX;
126
127	err = lp3944_reg_write(client, psc_reg, psc_value);
128
129	return err;
130}
131
132/**
133 * Set the duty cycle for DIM status
134 *
135 * @client: the i2c client
136 * @dim: either LP3944_DIM0 or LP3944_DIM1
137 * @duty_cycle: percentage of a period during which a led is ON
138 */
139static int lp3944_dim_set_dutycycle(struct i2c_client *client, u8 dim,
140				    u8 duty_cycle)
141{
142	u8 pwm_reg;
143	u8 pwm_value;
144	int err;
145
146	if (dim == LP3944_DIM0)
147		pwm_reg = LP3944_REG_PWM0;
148	else if (dim == LP3944_DIM1)
149		pwm_reg = LP3944_REG_PWM1;
150	else
151		return -EINVAL;
152
153	/* Convert duty cycle to PWM value */
154	if (duty_cycle > LP3944_DUTY_CYCLE_MAX)
155		return -EINVAL;
156
157	pwm_value = (duty_cycle * 255) / LP3944_DUTY_CYCLE_MAX;
158
159	err = lp3944_reg_write(client, pwm_reg, pwm_value);
160
161	return err;
162}
163
164/**
165 * Set the led status
166 *
167 * @led: a lp3944_led_data structure
168 * @status: one of LP3944_LED_STATUS_OFF
169 *                 LP3944_LED_STATUS_ON
170 *                 LP3944_LED_STATUS_DIM0
171 *                 LP3944_LED_STATUS_DIM1
172 */
173static int lp3944_led_set(struct lp3944_led_data *led, u8 status)
174{
175	struct lp3944_data *data = i2c_get_clientdata(led->client);
176	u8 id = led->id;
177	u8 reg;
178	u8 val = 0;
179	int err;
180
181	dev_dbg(&led->client->dev, "%s: %s, status before normalization:%d\n",
182		__func__, led->ldev.name, status);
183
184	switch (id) {
185	case LP3944_LED0:
186	case LP3944_LED1:
187	case LP3944_LED2:
188	case LP3944_LED3:
189		reg = LP3944_REG_LS0;
190		break;
191	case LP3944_LED4:
192	case LP3944_LED5:
193	case LP3944_LED6:
194	case LP3944_LED7:
195		id -= LP3944_LED4;
196		reg = LP3944_REG_LS1;
197		break;
198	default:
199		return -EINVAL;
200	}
201
202	if (status > LP3944_LED_STATUS_DIM1)
203		return -EINVAL;
204
205	/* invert only 0 and 1, leave unchanged the other values,
206	 * remember we are abusing status to set blink patterns
207	 */
208	if (led->type == LP3944_LED_TYPE_LED_INVERTED && status < 2)
209		status = 1 - status;
210
211	mutex_lock(&data->lock);
212	lp3944_reg_read(led->client, reg, &val);
213
214	val &= ~(LP3944_LED_STATUS_MASK << (id << 1));
215	val |= (status << (id << 1));
216
217	dev_dbg(&led->client->dev, "%s: %s, reg:%d id:%d status:%d val:%#x\n",
218		__func__, led->ldev.name, reg, id, status, val);
219
220	/* set led status */
221	err = lp3944_reg_write(led->client, reg, val);
222	mutex_unlock(&data->lock);
223
224	return err;
225}
226
227static int lp3944_led_set_blink(struct led_classdev *led_cdev,
228				unsigned long *delay_on,
229				unsigned long *delay_off)
230{
231	struct lp3944_led_data *led = ldev_to_led(led_cdev);
232	u16 period;
233	u8 duty_cycle;
234	int err;
235
236	/* units are in ms */
237	if (*delay_on + *delay_off > LP3944_PERIOD_MAX)
238		return -EINVAL;
239
240	if (*delay_on == 0 && *delay_off == 0) {
241		/* Special case: the leds subsystem requires a default user
242		 * friendly blink pattern for the LED.  Let's blink the led
243		 * slowly (1Hz).
244		 */
245		*delay_on = 500;
246		*delay_off = 500;
247	}
248
249	period = (*delay_on) + (*delay_off);
250
251	/* duty_cycle is the percentage of period during which the led is ON */
252	duty_cycle = 100 * (*delay_on) / period;
253
254	/* invert duty cycle for inverted leds, this has the same effect of
255	 * swapping delay_on and delay_off
256	 */
257	if (led->type == LP3944_LED_TYPE_LED_INVERTED)
258		duty_cycle = 100 - duty_cycle;
259
260	/* NOTE: using always the first DIM mode, this means that all leds
261	 * will have the same blinking pattern.
262	 *
263	 * We could find a way later to have two leds blinking in hardware
264	 * with different patterns at the same time, falling back to software
265	 * control for the other ones.
266	 */
267	err = lp3944_dim_set_period(led->client, LP3944_DIM0, period);
268	if (err)
269		return err;
270
271	err = lp3944_dim_set_dutycycle(led->client, LP3944_DIM0, duty_cycle);
272	if (err)
273		return err;
274
275	dev_dbg(&led->client->dev, "%s: OK hardware accelerated blink!\n",
276		__func__);
277
278	led->status = LP3944_LED_STATUS_DIM0;
279	schedule_work(&led->work);
280
281	return 0;
282}
283
284static void lp3944_led_set_brightness(struct led_classdev *led_cdev,
285				      enum led_brightness brightness)
286{
287	struct lp3944_led_data *led = ldev_to_led(led_cdev);
288
289	dev_dbg(&led->client->dev, "%s: %s, %d\n",
290		__func__, led_cdev->name, brightness);
291
292	led->status = !!brightness;
293	schedule_work(&led->work);
294}
295
296static void lp3944_led_work(struct work_struct *work)
297{
298	struct lp3944_led_data *led;
299
300	led = container_of(work, struct lp3944_led_data, work);
301	lp3944_led_set(led, led->status);
302}
303
304static int lp3944_configure(struct i2c_client *client,
305			    struct lp3944_data *data,
306			    struct lp3944_platform_data *pdata)
307{
308	int i, err = 0;
309
310	for (i = 0; i < pdata->leds_size; i++) {
311		struct lp3944_led *pled = &pdata->leds[i];
312		struct lp3944_led_data *led = &data->leds[i];
313		led->client = client;
314		led->id = i;
315
316		switch (pled->type) {
317
318		case LP3944_LED_TYPE_LED:
319		case LP3944_LED_TYPE_LED_INVERTED:
320			led->type = pled->type;
321			led->status = pled->status;
322			led->ldev.name = pled->name;
323			led->ldev.max_brightness = 1;
324			led->ldev.brightness_set = lp3944_led_set_brightness;
325			led->ldev.blink_set = lp3944_led_set_blink;
326			led->ldev.flags = LED_CORE_SUSPENDRESUME;
327
328			INIT_WORK(&led->work, lp3944_led_work);
329			err = led_classdev_register(&client->dev, &led->ldev);
330			if (err < 0) {
331				dev_err(&client->dev,
332					"couldn't register LED %s\n",
333					led->ldev.name);
334				goto exit;
335			}
336
337			/* to expose the default value to userspace */
338			led->ldev.brightness =
339					(enum led_brightness) led->status;
340
341			/* Set the default led status */
342			err = lp3944_led_set(led, led->status);
343			if (err < 0) {
344				dev_err(&client->dev,
345					"%s couldn't set STATUS %d\n",
346					led->ldev.name, led->status);
347				goto exit;
348			}
349			break;
350
351		case LP3944_LED_TYPE_NONE:
352		default:
353			break;
354
355		}
356	}
357	return 0;
358
359exit:
360	if (i > 0)
361		for (i = i - 1; i >= 0; i--)
362			switch (pdata->leds[i].type) {
363
364			case LP3944_LED_TYPE_LED:
365			case LP3944_LED_TYPE_LED_INVERTED:
366				led_classdev_unregister(&data->leds[i].ldev);
367				cancel_work_sync(&data->leds[i].work);
368				break;
369
370			case LP3944_LED_TYPE_NONE:
371			default:
372				break;
373			}
374
375	return err;
376}
377
378static int lp3944_probe(struct i2c_client *client,
379				  const struct i2c_device_id *id)
380{
381	struct lp3944_platform_data *lp3944_pdata =
382			dev_get_platdata(&client->dev);
383	struct lp3944_data *data;
384	int err;
385
386	if (lp3944_pdata == NULL) {
387		dev_err(&client->dev, "no platform data\n");
388		return -EINVAL;
389	}
390
391	/* Let's see whether this adapter can support what we need. */
392	if (!i2c_check_functionality(client->adapter,
393				I2C_FUNC_SMBUS_BYTE_DATA)) {
394		dev_err(&client->dev, "insufficient functionality!\n");
395		return -ENODEV;
396	}
397
398	data = devm_kzalloc(&client->dev, sizeof(struct lp3944_data),
399			GFP_KERNEL);
400	if (!data)
401		return -ENOMEM;
402
403	data->client = client;
404	i2c_set_clientdata(client, data);
405
406	mutex_init(&data->lock);
407
408	err = lp3944_configure(client, data, lp3944_pdata);
409	if (err < 0)
410		return err;
411
412	dev_info(&client->dev, "lp3944 enabled\n");
413	return 0;
414}
415
416static int lp3944_remove(struct i2c_client *client)
417{
418	struct lp3944_platform_data *pdata = dev_get_platdata(&client->dev);
419	struct lp3944_data *data = i2c_get_clientdata(client);
420	int i;
421
422	for (i = 0; i < pdata->leds_size; i++)
423		switch (data->leds[i].type) {
424		case LP3944_LED_TYPE_LED:
425		case LP3944_LED_TYPE_LED_INVERTED:
426			led_classdev_unregister(&data->leds[i].ldev);
427			cancel_work_sync(&data->leds[i].work);
428			break;
429
430		case LP3944_LED_TYPE_NONE:
431		default:
432			break;
433		}
434
435	return 0;
436}
437
438/* lp3944 i2c driver struct */
439static const struct i2c_device_id lp3944_id[] = {
440	{"lp3944", 0},
441	{}
442};
443
444MODULE_DEVICE_TABLE(i2c, lp3944_id);
445
446static struct i2c_driver lp3944_driver = {
447	.driver   = {
448		   .name = "lp3944",
449	},
450	.probe    = lp3944_probe,
451	.remove   = lp3944_remove,
452	.id_table = lp3944_id,
453};
454
455module_i2c_driver(lp3944_driver);
456
457MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
458MODULE_DESCRIPTION("LP3944 Fun Light Chip");
459MODULE_LICENSE("GPL");
460