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 */
63struct lp3944_led_data {
64	u8 id;
65	enum lp3944_type type;
66	struct led_classdev ldev;
67	struct i2c_client *client;
68};
69
70struct lp3944_data {
71	struct mutex lock;
72	struct i2c_client *client;
73	struct lp3944_led_data leds[LP3944_LEDS_MAX];
74};
75
76static 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
89static 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 */
101static 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 */
132static 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 */
166static 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
223static 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
279static 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
290static 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
344exit:
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
362static 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
399static 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 */
419static const struct i2c_device_id lp3944_id[] = {
420	{"lp3944", 0},
421	{}
422};
423
424MODULE_DEVICE_TABLE(i2c, lp3944_id);
425
426static 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
435module_i2c_driver(lp3944_driver);
436
437MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
438MODULE_DESCRIPTION("LP3944 Fun Light Chip");
439MODULE_LICENSE("GPL");
440