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Antonio Ospite5054d392009-06-19 13:55:42 +02001/*
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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090031#include <linux/slab.h>
Antonio Ospite5054d392009-06-19 13:55:42 +020032#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 -EINVAL;
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 = led->status;
339
340 /* Set the default led status */
341 err = lp3944_led_set(led, led->status);
342 if (err < 0) {
343 dev_err(&client->dev,
344 "%s couldn't set STATUS %d\n",
345 led->ldev.name, led->status);
346 goto exit;
347 }
348 break;
349
350 case LP3944_LED_TYPE_NONE:
351 default:
352 break;
353
354 }
355 }
356 return 0;
357
358exit:
359 if (i > 0)
360 for (i = i - 1; i >= 0; i--)
361 switch (pdata->leds[i].type) {
362
363 case LP3944_LED_TYPE_LED:
364 case LP3944_LED_TYPE_LED_INVERTED:
365 led_classdev_unregister(&data->leds[i].ldev);
366 cancel_work_sync(&data->leds[i].work);
367 break;
368
369 case LP3944_LED_TYPE_NONE:
370 default:
371 break;
372 }
373
374 return err;
375}
376
377static int __devinit lp3944_probe(struct i2c_client *client,
378 const struct i2c_device_id *id)
379{
380 struct lp3944_platform_data *lp3944_pdata = client->dev.platform_data;
381 struct lp3944_data *data;
382
383 if (lp3944_pdata == NULL) {
384 dev_err(&client->dev, "no platform data\n");
385 return -EINVAL;
386 }
387
388 /* Let's see whether this adapter can support what we need. */
389 if (!i2c_check_functionality(client->adapter,
390 I2C_FUNC_SMBUS_BYTE_DATA)) {
391 dev_err(&client->dev, "insufficient functionality!\n");
392 return -ENODEV;
393 }
394
395 data = kzalloc(sizeof(struct lp3944_data), GFP_KERNEL);
396 if (!data)
397 return -ENOMEM;
398
399 data->client = client;
400 i2c_set_clientdata(client, data);
401
402 mutex_init(&data->lock);
403
404 dev_info(&client->dev, "lp3944 enabled\n");
405
406 lp3944_configure(client, data, lp3944_pdata);
407 return 0;
408}
409
410static int __devexit lp3944_remove(struct i2c_client *client)
411{
412 struct lp3944_platform_data *pdata = client->dev.platform_data;
413 struct lp3944_data *data = i2c_get_clientdata(client);
414 int i;
415
416 for (i = 0; i < pdata->leds_size; i++)
417 switch (data->leds[i].type) {
418 case LP3944_LED_TYPE_LED:
419 case LP3944_LED_TYPE_LED_INVERTED:
420 led_classdev_unregister(&data->leds[i].ldev);
421 cancel_work_sync(&data->leds[i].work);
422 break;
423
424 case LP3944_LED_TYPE_NONE:
425 default:
426 break;
427 }
428
429 kfree(data);
430 i2c_set_clientdata(client, NULL);
431
432 return 0;
433}
434
435/* lp3944 i2c driver struct */
436static const struct i2c_device_id lp3944_id[] = {
437 {"lp3944", 0},
438 {}
439};
440
441MODULE_DEVICE_TABLE(i2c, lp3944_id);
442
443static struct i2c_driver lp3944_driver = {
444 .driver = {
445 .name = "lp3944",
446 },
447 .probe = lp3944_probe,
448 .remove = __devexit_p(lp3944_remove),
449 .id_table = lp3944_id,
450};
451
452static int __init lp3944_module_init(void)
453{
454 return i2c_add_driver(&lp3944_driver);
455}
456
457static void __exit lp3944_module_exit(void)
458{
459 i2c_del_driver(&lp3944_driver);
460}
461
462module_init(lp3944_module_init);
463module_exit(lp3944_module_exit);
464
465MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
466MODULE_DESCRIPTION("LP3944 Fun Light Chip");
467MODULE_LICENSE("GPL");