aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/leds/leds-pca955x.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/leds/leds-pca955x.c')
-rw-r--r--drivers/leds/leds-pca955x.c384
1 files changed, 384 insertions, 0 deletions
diff --git a/drivers/leds/leds-pca955x.c b/drivers/leds/leds-pca955x.c
new file mode 100644
index 000000000000..146c06972863
--- /dev/null
+++ b/drivers/leds/leds-pca955x.c
@@ -0,0 +1,384 @@
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
52/* LED select registers determine the source that drives LED outputs */
53#define PCA955X_LS_LED_ON 0x0 /* Output LOW */
54#define PCA955X_LS_LED_OFF 0x1 /* Output HI-Z */
55#define PCA955X_LS_BLINK0 0x2 /* Blink at PWM0 rate */
56#define PCA955X_LS_BLINK1 0x3 /* Blink at PWM1 rate */
57
58enum pca955x_type {
59 pca9550,
60 pca9551,
61 pca9552,
62 pca9553,
63};
64
65struct pca955x_chipdef {
66 int bits;
67 u8 slv_addr; /* 7-bit slave address mask */
68 int slv_addr_shift; /* Number of bits to ignore */
69};
70
71static struct pca955x_chipdef pca955x_chipdefs[] = {
72 [pca9550] = {
73 .bits = 2,
74 .slv_addr = /* 110000x */ 0x60,
75 .slv_addr_shift = 1,
76 },
77 [pca9551] = {
78 .bits = 8,
79 .slv_addr = /* 1100xxx */ 0x60,
80 .slv_addr_shift = 3,
81 },
82 [pca9552] = {
83 .bits = 16,
84 .slv_addr = /* 1100xxx */ 0x60,
85 .slv_addr_shift = 3,
86 },
87 [pca9553] = {
88 .bits = 4,
89 .slv_addr = /* 110001x */ 0x62,
90 .slv_addr_shift = 1,
91 },
92};
93
94static const struct i2c_device_id pca955x_id[] = {
95 { "pca9550", pca9550 },
96 { "pca9551", pca9551 },
97 { "pca9552", pca9552 },
98 { "pca9553", pca9553 },
99 { }
100};
101MODULE_DEVICE_TABLE(i2c, pca955x_id);
102
103struct pca955x_led {
104 struct pca955x_chipdef *chipdef;
105 struct i2c_client *client;
106 struct work_struct work;
107 spinlock_t lock;
108 enum led_brightness brightness;
109 struct led_classdev led_cdev;
110 int led_num; /* 0 .. 15 potentially */
111 char name[32];
112};
113
114/* 8 bits per input register */
115static inline int pca95xx_num_input_regs(int bits)
116{
117 return (bits + 7) / 8;
118}
119
120/* 4 bits per LED selector register */
121static inline int pca95xx_num_led_regs(int bits)
122{
123 return (bits + 3) / 4;
124}
125
126/*
127 * Return an LED selector register value based on an existing one, with
128 * the appropriate 2-bit state value set for the given LED number (0-3).
129 */
130static inline u8 pca955x_ledsel(u8 oldval, int led_num, int state)
131{
132 return (oldval & (~(0x3 << (led_num << 1)))) |
133 ((state & 0x3) << (led_num << 1));
134}
135
136/*
137 * Write to frequency prescaler register, used to program the
138 * period of the PWM output. period = (PSCx + 1) / 38
139 */
140static void pca955x_write_psc(struct i2c_client *client, int n, u8 val)
141{
142 struct pca955x_led *pca955x = i2c_get_clientdata(client);
143
144 i2c_smbus_write_byte_data(client,
145 pca95xx_num_input_regs(pca955x->chipdef->bits) + 2*n,
146 val);
147}
148
149/*
150 * Write to PWM register, which determines the duty cycle of the
151 * output. LED is OFF when the count is less than the value of this
152 * register, and ON when it is greater. If PWMx == 0, LED is always OFF.
153 *
154 * Duty cycle is (256 - PWMx) / 256
155 */
156static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val)
157{
158 struct pca955x_led *pca955x = i2c_get_clientdata(client);
159
160 i2c_smbus_write_byte_data(client,
161 pca95xx_num_input_regs(pca955x->chipdef->bits) + 1 + 2*n,
162 val);
163}
164
165/*
166 * Write to LED selector register, which determines the source that
167 * drives the LED output.
168 */
169static void pca955x_write_ls(struct i2c_client *client, int n, u8 val)
170{
171 struct pca955x_led *pca955x = i2c_get_clientdata(client);
172
173 i2c_smbus_write_byte_data(client,
174 pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n,
175 val);
176}
177
178/*
179 * Read the LED selector register, which determines the source that
180 * drives the LED output.
181 */
182static u8 pca955x_read_ls(struct i2c_client *client, int n)
183{
184 struct pca955x_led *pca955x = i2c_get_clientdata(client);
185
186 return (u8) i2c_smbus_read_byte_data(client,
187 pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n);
188}
189
190static void pca955x_led_work(struct work_struct *work)
191{
192 struct pca955x_led *pca955x;
193 u8 ls;
194 int chip_ls; /* which LSx to use (0-3 potentially) */
195 int ls_led; /* which set of bits within LSx to use (0-3) */
196
197 pca955x = container_of(work, struct pca955x_led, work);
198 chip_ls = pca955x->led_num / 4;
199 ls_led = pca955x->led_num % 4;
200
201 ls = pca955x_read_ls(pca955x->client, chip_ls);
202
203 switch (pca955x->brightness) {
204 case LED_FULL:
205 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_ON);
206 break;
207 case LED_OFF:
208 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_OFF);
209 break;
210 case LED_HALF:
211 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK0);
212 break;
213 default:
214 /*
215 * Use PWM1 for all other values. This has the unwanted
216 * side effect of making all LEDs on the chip share the
217 * same brightness level if set to a value other than
218 * OFF, HALF, or FULL. But, this is probably better than
219 * just turning off for all other values.
220 */
221 pca955x_write_pwm(pca955x->client, 1, 255-pca955x->brightness);
222 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK1);
223 break;
224 }
225
226 pca955x_write_ls(pca955x->client, chip_ls, ls);
227}
228
229void pca955x_led_set(struct led_classdev *led_cdev, enum led_brightness value)
230{
231 struct pca955x_led *pca955x;
232
233 pca955x = container_of(led_cdev, struct pca955x_led, led_cdev);
234
235 spin_lock(&pca955x->lock);
236 pca955x->brightness = value;
237
238 /*
239 * Must use workqueue for the actual I/O since I2C operations
240 * can sleep.
241 */
242 schedule_work(&pca955x->work);
243
244 spin_unlock(&pca955x->lock);
245}
246
247static int __devinit pca955x_probe(struct i2c_client *client,
248 const struct i2c_device_id *id)
249{
250 struct pca955x_led *pca955x;
251 int i;
252 int err = -ENODEV;
253 struct pca955x_chipdef *chip;
254 struct i2c_adapter *adapter;
255 struct led_platform_data *pdata;
256
257 chip = &pca955x_chipdefs[id->driver_data];
258 adapter = to_i2c_adapter(client->dev.parent);
259 pdata = client->dev.platform_data;
260
261 /* Make sure the slave address / chip type combo given is possible */
262 if ((client->addr & ~((1 << chip->slv_addr_shift) - 1)) !=
263 chip->slv_addr) {
264 dev_err(&client->dev, "invalid slave address %02x\n",
265 client->addr);
266 return -ENODEV;
267 }
268
269 printk(KERN_INFO "leds-pca955x: Using %s %d-bit LED driver at "
270 "slave address 0x%02x\n",
271 id->name, chip->bits, client->addr);
272
273 if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
274 return -EIO;
275
276 if (pdata) {
277 if (pdata->num_leds != chip->bits) {
278 dev_err(&client->dev, "board info claims %d LEDs"
279 " on a %d-bit chip\n",
280 pdata->num_leds, chip->bits);
281 return -ENODEV;
282 }
283 }
284
285 for (i = 0; i < chip->bits; i++) {
286 pca955x = kzalloc(sizeof(struct pca955x_led), GFP_KERNEL);
287 if (!pca955x) {
288 err = -ENOMEM;
289 goto exit;
290 }
291
292 pca955x->chipdef = chip;
293 pca955x->client = client;
294 pca955x->led_num = i;
295 /* Platform data can specify LED names and default triggers */
296 if (pdata) {
297 if (pdata->leds[i].name)
298 snprintf(pca955x->name, 32, "pca955x:%s",
299 pdata->leds[i].name);
300 if (pdata->leds[i].default_trigger)
301 pca955x->led_cdev.default_trigger =
302 pdata->leds[i].default_trigger;
303 } else {
304 snprintf(pca955x->name, 32, "pca955x:%d", i);
305 }
306 spin_lock_init(&pca955x->lock);
307
308 pca955x->led_cdev.name = pca955x->name;
309 pca955x->led_cdev.brightness_set =
310 pca955x_led_set;
311
312 /*
313 * Client data is a pointer to the _first_ pca955x_led
314 * struct
315 */
316 if (i == 0)
317 i2c_set_clientdata(client, pca955x);
318
319 INIT_WORK(&(pca955x->work), pca955x_led_work);
320
321 led_classdev_register(&client->dev, &(pca955x->led_cdev));
322 }
323
324 /* Turn off LEDs */
325 for (i = 0; i < pca95xx_num_led_regs(chip->bits); i++)
326 pca955x_write_ls(client, i, 0x55);
327
328 /* PWM0 is used for half brightness or 50% duty cycle */
329 pca955x_write_pwm(client, 0, 255-LED_HALF);
330
331 /* PWM1 is used for variable brightness, default to OFF */
332 pca955x_write_pwm(client, 1, 0);
333
334 /* Set to fast frequency so we do not see flashing */
335 pca955x_write_psc(client, 0, 0);
336 pca955x_write_psc(client, 1, 0);
337
338 return 0;
339exit:
340 return err;
341}
342
343static int __devexit pca955x_remove(struct i2c_client *client)
344{
345 struct pca955x_led *pca955x = i2c_get_clientdata(client);
346 int leds = pca955x->chipdef->bits;
347 int i;
348
349 for (i = 0; i < leds; i++) {
350 led_classdev_unregister(&(pca955x->led_cdev));
351 cancel_work_sync(&(pca955x->work));
352 kfree(pca955x);
353 pca955x = pca955x + 1;
354 }
355
356 return 0;
357}
358
359static struct i2c_driver pca955x_driver = {
360 .driver = {
361 .name = "leds-pca955x",
362 .owner = THIS_MODULE,
363 },
364 .probe = pca955x_probe,
365 .remove = __devexit_p(pca955x_remove),
366 .id_table = pca955x_id,
367};
368
369static int __init pca955x_leds_init(void)
370{
371 return i2c_add_driver(&pca955x_driver);
372}
373
374static void __exit pca955x_leds_exit(void)
375{
376 i2c_del_driver(&pca955x_driver);
377}
378
379module_init(pca955x_leds_init);
380module_exit(pca955x_leds_exit);
381
382MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>");
383MODULE_DESCRIPTION("PCA955x LED driver");
384MODULE_LICENSE("GPL v2");