Root/drivers/leds/leds-lp3944.c

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 = 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 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    int err;
383
384    if (lp3944_pdata == NULL) {
385        dev_err(&client->dev, "no platform data\n");
386        return -EINVAL;
387    }
388
389    /* Let's see whether this adapter can support what we need. */
390    if (!i2c_check_functionality(client->adapter,
391                I2C_FUNC_SMBUS_BYTE_DATA)) {
392        dev_err(&client->dev, "insufficient functionality!\n");
393        return -ENODEV;
394    }
395
396    data = devm_kzalloc(&client->dev, sizeof(struct lp3944_data),
397            GFP_KERNEL);
398    if (!data)
399        return -ENOMEM;
400
401    data->client = client;
402    i2c_set_clientdata(client, data);
403
404    mutex_init(&data->lock);
405
406    err = lp3944_configure(client, data, lp3944_pdata);
407    if (err < 0)
408        return err;
409
410    dev_info(&client->dev, "lp3944 enabled\n");
411    return 0;
412}
413
414static int lp3944_remove(struct i2c_client *client)
415{
416    struct lp3944_platform_data *pdata = client->dev.platform_data;
417    struct lp3944_data *data = i2c_get_clientdata(client);
418    int i;
419
420    for (i = 0; i < pdata->leds_size; i++)
421        switch (data->leds[i].type) {
422        case LP3944_LED_TYPE_LED:
423        case LP3944_LED_TYPE_LED_INVERTED:
424            led_classdev_unregister(&data->leds[i].ldev);
425            cancel_work_sync(&data->leds[i].work);
426            break;
427
428        case LP3944_LED_TYPE_NONE:
429        default:
430            break;
431        }
432
433    return 0;
434}
435
436/* lp3944 i2c driver struct */
437static const struct i2c_device_id lp3944_id[] = {
438    {"lp3944", 0},
439    {}
440};
441
442MODULE_DEVICE_TABLE(i2c, lp3944_id);
443
444static struct i2c_driver lp3944_driver = {
445    .driver = {
446           .name = "lp3944",
447    },
448    .probe = lp3944_probe,
449    .remove = lp3944_remove,
450    .id_table = lp3944_id,
451};
452
453module_i2c_driver(lp3944_driver);
454
455MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
456MODULE_DESCRIPTION("LP3944 Fun Light Chip");
457MODULE_LICENSE("GPL");
458

Archive Download this file

Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master

Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9



interactive