Root/drivers/leds/leds-pca955x.c

1/*
2 * Copyright 2007-2008 Extreme Engineering Solutions, Inc.
3 *
4 * Author: Nate Case <ncase@xes-inc.com>
5 *
6 * This file is subject to the terms and conditions of version 2 of
7 * the GNU General Public License. See the file COPYING in the main
8 * directory of this archive for more details.
9 *
10 * LED driver for various PCA955x I2C LED drivers
11 *
12 * Supported devices:
13 *
14 * Device Description 7-bit slave address
15 * ------ ----------- -------------------
16 * PCA9550 2-bit driver 0x60 .. 0x61
17 * PCA9551 8-bit driver 0x60 .. 0x67
18 * PCA9552 16-bit driver 0x60 .. 0x67
19 * PCA9553/01 4-bit driver 0x62
20 * PCA9553/02 4-bit driver 0x63
21 *
22 * Philips PCA955x LED driver chips follow a register map as shown below:
23 *
24 * Control Register Description
25 * ---------------- -----------
26 * 0x0 Input register 0
27 * ..
28 * NUM_INPUT_REGS - 1 Last Input register X
29 *
30 * NUM_INPUT_REGS Frequency prescaler 0
31 * NUM_INPUT_REGS + 1 PWM register 0
32 * NUM_INPUT_REGS + 2 Frequency prescaler 1
33 * NUM_INPUT_REGS + 3 PWM register 1
34 *
35 * NUM_INPUT_REGS + 4 LED selector 0
36 * NUM_INPUT_REGS + 4
37 * + NUM_LED_REGS - 1 Last LED selector
38 *
39 * where NUM_INPUT_REGS and NUM_LED_REGS vary depending on how many
40 * bits the chip supports.
41 */
42
43#include <linux/module.h>
44#include <linux/delay.h>
45#include <linux/string.h>
46#include <linux/ctype.h>
47#include <linux/leds.h>
48#include <linux/err.h>
49#include <linux/i2c.h>
50#include <linux/workqueue.h>
51#include <linux/slab.h>
52
53/* LED select registers determine the source that drives LED outputs */
54#define PCA955X_LS_LED_ON 0x0 /* Output LOW */
55#define PCA955X_LS_LED_OFF 0x1 /* Output HI-Z */
56#define PCA955X_LS_BLINK0 0x2 /* Blink at PWM0 rate */
57#define PCA955X_LS_BLINK1 0x3 /* Blink at PWM1 rate */
58
59enum pca955x_type {
60    pca9550,
61    pca9551,
62    pca9552,
63    pca9553,
64};
65
66struct pca955x_chipdef {
67    int bits;
68    u8 slv_addr; /* 7-bit slave address mask */
69    int slv_addr_shift; /* Number of bits to ignore */
70};
71
72static struct pca955x_chipdef pca955x_chipdefs[] = {
73    [pca9550] = {
74        .bits = 2,
75        .slv_addr = /* 110000x */ 0x60,
76        .slv_addr_shift = 1,
77    },
78    [pca9551] = {
79        .bits = 8,
80        .slv_addr = /* 1100xxx */ 0x60,
81        .slv_addr_shift = 3,
82    },
83    [pca9552] = {
84        .bits = 16,
85        .slv_addr = /* 1100xxx */ 0x60,
86        .slv_addr_shift = 3,
87    },
88    [pca9553] = {
89        .bits = 4,
90        .slv_addr = /* 110001x */ 0x62,
91        .slv_addr_shift = 1,
92    },
93};
94
95static const struct i2c_device_id pca955x_id[] = {
96    { "pca9550", pca9550 },
97    { "pca9551", pca9551 },
98    { "pca9552", pca9552 },
99    { "pca9553", pca9553 },
100    { }
101};
102MODULE_DEVICE_TABLE(i2c, pca955x_id);
103
104struct pca955x {
105    struct mutex lock;
106    struct pca955x_led *leds;
107    struct pca955x_chipdef *chipdef;
108    struct i2c_client *client;
109};
110
111struct pca955x_led {
112    struct pca955x *pca955x;
113    struct work_struct work;
114    enum led_brightness brightness;
115    struct led_classdev led_cdev;
116    int led_num; /* 0 .. 15 potentially */
117    char name[32];
118};
119
120/* 8 bits per input register */
121static inline int pca95xx_num_input_regs(int bits)
122{
123    return (bits + 7) / 8;
124}
125
126/* 4 bits per LED selector register */
127static inline int pca95xx_num_led_regs(int bits)
128{
129    return (bits + 3) / 4;
130}
131
132/*
133 * Return an LED selector register value based on an existing one, with
134 * the appropriate 2-bit state value set for the given LED number (0-3).
135 */
136static inline u8 pca955x_ledsel(u8 oldval, int led_num, int state)
137{
138    return (oldval & (~(0x3 << (led_num << 1)))) |
139        ((state & 0x3) << (led_num << 1));
140}
141
142/*
143 * Write to frequency prescaler register, used to program the
144 * period of the PWM output. period = (PSCx + 1) / 38
145 */
146static void pca955x_write_psc(struct i2c_client *client, int n, u8 val)
147{
148    struct pca955x *pca955x = i2c_get_clientdata(client);
149
150    i2c_smbus_write_byte_data(client,
151        pca95xx_num_input_regs(pca955x->chipdef->bits) + 2*n,
152        val);
153}
154
155/*
156 * Write to PWM register, which determines the duty cycle of the
157 * output. LED is OFF when the count is less than the value of this
158 * register, and ON when it is greater. If PWMx == 0, LED is always OFF.
159 *
160 * Duty cycle is (256 - PWMx) / 256
161 */
162static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val)
163{
164    struct pca955x *pca955x = i2c_get_clientdata(client);
165
166    i2c_smbus_write_byte_data(client,
167        pca95xx_num_input_regs(pca955x->chipdef->bits) + 1 + 2*n,
168        val);
169}
170
171/*
172 * Write to LED selector register, which determines the source that
173 * drives the LED output.
174 */
175static void pca955x_write_ls(struct i2c_client *client, int n, u8 val)
176{
177    struct pca955x *pca955x = i2c_get_clientdata(client);
178
179    i2c_smbus_write_byte_data(client,
180        pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n,
181        val);
182}
183
184/*
185 * Read the LED selector register, which determines the source that
186 * drives the LED output.
187 */
188static u8 pca955x_read_ls(struct i2c_client *client, int n)
189{
190    struct pca955x *pca955x = i2c_get_clientdata(client);
191
192    return (u8) i2c_smbus_read_byte_data(client,
193        pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n);
194}
195
196static void pca955x_led_work(struct work_struct *work)
197{
198    struct pca955x_led *pca955x_led;
199    struct pca955x *pca955x;
200    u8 ls;
201    int chip_ls; /* which LSx to use (0-3 potentially) */
202    int ls_led; /* which set of bits within LSx to use (0-3) */
203
204    pca955x_led = container_of(work, struct pca955x_led, work);
205    pca955x = pca955x_led->pca955x;
206
207    chip_ls = pca955x_led->led_num / 4;
208    ls_led = pca955x_led->led_num % 4;
209
210    mutex_lock(&pca955x->lock);
211
212    ls = pca955x_read_ls(pca955x->client, chip_ls);
213
214    switch (pca955x_led->brightness) {
215    case LED_FULL:
216        ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_ON);
217        break;
218    case LED_OFF:
219        ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_OFF);
220        break;
221    case LED_HALF:
222        ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK0);
223        break;
224    default:
225        /*
226         * Use PWM1 for all other values. This has the unwanted
227         * side effect of making all LEDs on the chip share the
228         * same brightness level if set to a value other than
229         * OFF, HALF, or FULL. But, this is probably better than
230         * just turning off for all other values.
231         */
232        pca955x_write_pwm(pca955x->client, 1,
233                255 - pca955x_led->brightness);
234        ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK1);
235        break;
236    }
237
238    pca955x_write_ls(pca955x->client, chip_ls, ls);
239
240    mutex_unlock(&pca955x->lock);
241}
242
243static void pca955x_led_set(struct led_classdev *led_cdev, enum led_brightness value)
244{
245    struct pca955x_led *pca955x;
246
247    pca955x = container_of(led_cdev, struct pca955x_led, led_cdev);
248
249    pca955x->brightness = value;
250
251    /*
252     * Must use workqueue for the actual I/O since I2C operations
253     * can sleep.
254     */
255    schedule_work(&pca955x->work);
256}
257
258static int pca955x_probe(struct i2c_client *client,
259                    const struct i2c_device_id *id)
260{
261    struct pca955x *pca955x;
262    struct pca955x_led *pca955x_led;
263    struct pca955x_chipdef *chip;
264    struct i2c_adapter *adapter;
265    struct led_platform_data *pdata;
266    int i, err;
267
268    chip = &pca955x_chipdefs[id->driver_data];
269    adapter = to_i2c_adapter(client->dev.parent);
270    pdata = client->dev.platform_data;
271
272    /* Make sure the slave address / chip type combo given is possible */
273    if ((client->addr & ~((1 << chip->slv_addr_shift) - 1)) !=
274        chip->slv_addr) {
275        dev_err(&client->dev, "invalid slave address %02x\n",
276                client->addr);
277        return -ENODEV;
278    }
279
280    dev_info(&client->dev, "leds-pca955x: Using %s %d-bit LED driver at "
281            "slave address 0x%02x\n",
282            id->name, chip->bits, client->addr);
283
284    if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
285        return -EIO;
286
287    if (pdata) {
288        if (pdata->num_leds != chip->bits) {
289            dev_err(&client->dev, "board info claims %d LEDs"
290                    " on a %d-bit chip\n",
291                    pdata->num_leds, chip->bits);
292            return -ENODEV;
293        }
294    }
295
296    pca955x = devm_kzalloc(&client->dev, sizeof(*pca955x), GFP_KERNEL);
297    if (!pca955x)
298        return -ENOMEM;
299
300    pca955x->leds = devm_kzalloc(&client->dev,
301            sizeof(*pca955x_led) * chip->bits, GFP_KERNEL);
302    if (!pca955x->leds)
303        return -ENOMEM;
304
305    i2c_set_clientdata(client, pca955x);
306
307    mutex_init(&pca955x->lock);
308    pca955x->client = client;
309    pca955x->chipdef = chip;
310
311    for (i = 0; i < chip->bits; i++) {
312        pca955x_led = &pca955x->leds[i];
313        pca955x_led->led_num = i;
314        pca955x_led->pca955x = pca955x;
315
316        /* Platform data can specify LED names and default triggers */
317        if (pdata) {
318            if (pdata->leds[i].name)
319                snprintf(pca955x_led->name,
320                    sizeof(pca955x_led->name), "pca955x:%s",
321                    pdata->leds[i].name);
322            if (pdata->leds[i].default_trigger)
323                pca955x_led->led_cdev.default_trigger =
324                    pdata->leds[i].default_trigger;
325        } else {
326            snprintf(pca955x_led->name, sizeof(pca955x_led->name),
327                 "pca955x:%d", i);
328        }
329
330        pca955x_led->led_cdev.name = pca955x_led->name;
331        pca955x_led->led_cdev.brightness_set = pca955x_led_set;
332
333        INIT_WORK(&pca955x_led->work, pca955x_led_work);
334
335        err = led_classdev_register(&client->dev,
336                    &pca955x_led->led_cdev);
337        if (err < 0)
338            goto exit;
339    }
340
341    /* Turn off LEDs */
342    for (i = 0; i < pca95xx_num_led_regs(chip->bits); i++)
343        pca955x_write_ls(client, i, 0x55);
344
345    /* PWM0 is used for half brightness or 50% duty cycle */
346    pca955x_write_pwm(client, 0, 255-LED_HALF);
347
348    /* PWM1 is used for variable brightness, default to OFF */
349    pca955x_write_pwm(client, 1, 0);
350
351    /* Set to fast frequency so we do not see flashing */
352    pca955x_write_psc(client, 0, 0);
353    pca955x_write_psc(client, 1, 0);
354
355    return 0;
356
357exit:
358    while (i--) {
359        led_classdev_unregister(&pca955x->leds[i].led_cdev);
360        cancel_work_sync(&pca955x->leds[i].work);
361    }
362
363    return err;
364}
365
366static int pca955x_remove(struct i2c_client *client)
367{
368    struct pca955x *pca955x = i2c_get_clientdata(client);
369    int i;
370
371    for (i = 0; i < pca955x->chipdef->bits; i++) {
372        led_classdev_unregister(&pca955x->leds[i].led_cdev);
373        cancel_work_sync(&pca955x->leds[i].work);
374    }
375
376    return 0;
377}
378
379static struct i2c_driver pca955x_driver = {
380    .driver = {
381        .name = "leds-pca955x",
382        .owner = THIS_MODULE,
383    },
384    .probe = pca955x_probe,
385    .remove = pca955x_remove,
386    .id_table = pca955x_id,
387};
388
389module_i2c_driver(pca955x_driver);
390
391MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>");
392MODULE_DESCRIPTION("PCA955x LED driver");
393MODULE_LICENSE("GPL v2");
394

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