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
59 enum pca955x_type {
60 pca9550,
61 pca9551,
62 pca9552,
63 pca9553,
64 };
65
66 struct 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
72 static 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
95 static const struct i2c_device_id pca955x_id[] = {
96 { "pca9550", pca9550 },
97 { "pca9551", pca9551 },
98 { "pca9552", pca9552 },
99 { "pca9553", pca9553 },
100 { }
101 };
102 MODULE_DEVICE_TABLE(i2c, pca955x_id);
103
104 struct pca955x_led {
105 struct pca955x_chipdef *chipdef;
106 struct i2c_client *client;
107 struct work_struct work;
108 spinlock_t lock;
109 enum led_brightness brightness;
110 struct led_classdev led_cdev;
111 int led_num; /* 0 .. 15 potentially */
112 char name[32];
113 };
114
115 /* 8 bits per input register */
pca95xx_num_input_regs(int bits)116 static inline int pca95xx_num_input_regs(int bits)
117 {
118 return (bits + 7) / 8;
119 }
120
121 /* 4 bits per LED selector register */
pca95xx_num_led_regs(int bits)122 static inline int pca95xx_num_led_regs(int bits)
123 {
124 return (bits + 3) / 4;
125 }
126
127 /*
128 * Return an LED selector register value based on an existing one, with
129 * the appropriate 2-bit state value set for the given LED number (0-3).
130 */
pca955x_ledsel(u8 oldval,int led_num,int state)131 static inline u8 pca955x_ledsel(u8 oldval, int led_num, int state)
132 {
133 return (oldval & (~(0x3 << (led_num << 1)))) |
134 ((state & 0x3) << (led_num << 1));
135 }
136
137 /*
138 * Write to frequency prescaler register, used to program the
139 * period of the PWM output. period = (PSCx + 1) / 38
140 */
pca955x_write_psc(struct i2c_client * client,int n,u8 val)141 static void pca955x_write_psc(struct i2c_client *client, int n, u8 val)
142 {
143 struct pca955x_led *pca955x = i2c_get_clientdata(client);
144
145 i2c_smbus_write_byte_data(client,
146 pca95xx_num_input_regs(pca955x->chipdef->bits) + 2*n,
147 val);
148 }
149
150 /*
151 * Write to PWM register, which determines the duty cycle of the
152 * output. LED is OFF when the count is less than the value of this
153 * register, and ON when it is greater. If PWMx == 0, LED is always OFF.
154 *
155 * Duty cycle is (256 - PWMx) / 256
156 */
pca955x_write_pwm(struct i2c_client * client,int n,u8 val)157 static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val)
158 {
159 struct pca955x_led *pca955x = i2c_get_clientdata(client);
160
161 i2c_smbus_write_byte_data(client,
162 pca95xx_num_input_regs(pca955x->chipdef->bits) + 1 + 2*n,
163 val);
164 }
165
166 /*
167 * Write to LED selector register, which determines the source that
168 * drives the LED output.
169 */
pca955x_write_ls(struct i2c_client * client,int n,u8 val)170 static void pca955x_write_ls(struct i2c_client *client, int n, u8 val)
171 {
172 struct pca955x_led *pca955x = i2c_get_clientdata(client);
173
174 i2c_smbus_write_byte_data(client,
175 pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n,
176 val);
177 }
178
179 /*
180 * Read the LED selector register, which determines the source that
181 * drives the LED output.
182 */
pca955x_read_ls(struct i2c_client * client,int n)183 static u8 pca955x_read_ls(struct i2c_client *client, int n)
184 {
185 struct pca955x_led *pca955x = i2c_get_clientdata(client);
186
187 return (u8) i2c_smbus_read_byte_data(client,
188 pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n);
189 }
190
pca955x_led_work(struct work_struct * work)191 static void pca955x_led_work(struct work_struct *work)
192 {
193 struct pca955x_led *pca955x;
194 u8 ls;
195 int chip_ls; /* which LSx to use (0-3 potentially) */
196 int ls_led; /* which set of bits within LSx to use (0-3) */
197
198 pca955x = container_of(work, struct pca955x_led, work);
199 chip_ls = pca955x->led_num / 4;
200 ls_led = pca955x->led_num % 4;
201
202 ls = pca955x_read_ls(pca955x->client, chip_ls);
203
204 switch (pca955x->brightness) {
205 case LED_FULL:
206 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_ON);
207 break;
208 case LED_OFF:
209 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_OFF);
210 break;
211 case LED_HALF:
212 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK0);
213 break;
214 default:
215 /*
216 * Use PWM1 for all other values. This has the unwanted
217 * side effect of making all LEDs on the chip share the
218 * same brightness level if set to a value other than
219 * OFF, HALF, or FULL. But, this is probably better than
220 * just turning off for all other values.
221 */
222 pca955x_write_pwm(pca955x->client, 1, 255-pca955x->brightness);
223 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK1);
224 break;
225 }
226
227 pca955x_write_ls(pca955x->client, chip_ls, ls);
228 }
229
pca955x_led_set(struct led_classdev * led_cdev,enum led_brightness value)230 static void pca955x_led_set(struct led_classdev *led_cdev, enum led_brightness value)
231 {
232 struct pca955x_led *pca955x;
233
234 pca955x = container_of(led_cdev, struct pca955x_led, led_cdev);
235
236 spin_lock(&pca955x->lock);
237 pca955x->brightness = value;
238
239 /*
240 * Must use workqueue for the actual I/O since I2C operations
241 * can sleep.
242 */
243 schedule_work(&pca955x->work);
244
245 spin_unlock(&pca955x->lock);
246 }
247
pca955x_probe(struct i2c_client * client,const struct i2c_device_id * id)248 static int __devinit pca955x_probe(struct i2c_client *client,
249 const struct i2c_device_id *id)
250 {
251 struct pca955x_led *pca955x;
252 struct pca955x_chipdef *chip;
253 struct i2c_adapter *adapter;
254 struct led_platform_data *pdata;
255 int i, err;
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 pca955x = kzalloc(sizeof(*pca955x) * chip->bits, GFP_KERNEL);
286 if (!pca955x)
287 return -ENOMEM;
288
289 i2c_set_clientdata(client, pca955x);
290
291 for (i = 0; i < chip->bits; i++) {
292 pca955x[i].chipdef = chip;
293 pca955x[i].client = client;
294 pca955x[i].led_num = i;
295
296 /* Platform data can specify LED names and default triggers */
297 if (pdata) {
298 if (pdata->leds[i].name)
299 snprintf(pca955x[i].name,
300 sizeof(pca955x[i].name), "pca955x:%s",
301 pdata->leds[i].name);
302 if (pdata->leds[i].default_trigger)
303 pca955x[i].led_cdev.default_trigger =
304 pdata->leds[i].default_trigger;
305 } else {
306 snprintf(pca955x[i].name, sizeof(pca955x[i].name),
307 "pca955x:%d", i);
308 }
309
310 spin_lock_init(&pca955x[i].lock);
311
312 pca955x[i].led_cdev.name = pca955x[i].name;
313 pca955x[i].led_cdev.brightness_set = pca955x_led_set;
314
315 INIT_WORK(&pca955x[i].work, pca955x_led_work);
316
317 err = led_classdev_register(&client->dev, &pca955x[i].led_cdev);
318 if (err < 0)
319 goto exit;
320 }
321
322 /* Turn off LEDs */
323 for (i = 0; i < pca95xx_num_led_regs(chip->bits); i++)
324 pca955x_write_ls(client, i, 0x55);
325
326 /* PWM0 is used for half brightness or 50% duty cycle */
327 pca955x_write_pwm(client, 0, 255-LED_HALF);
328
329 /* PWM1 is used for variable brightness, default to OFF */
330 pca955x_write_pwm(client, 1, 0);
331
332 /* Set to fast frequency so we do not see flashing */
333 pca955x_write_psc(client, 0, 0);
334 pca955x_write_psc(client, 1, 0);
335
336 return 0;
337
338 exit:
339 while (i--) {
340 led_classdev_unregister(&pca955x[i].led_cdev);
341 cancel_work_sync(&pca955x[i].work);
342 }
343
344 kfree(pca955x);
345
346 return err;
347 }
348
pca955x_remove(struct i2c_client * client)349 static int __devexit pca955x_remove(struct i2c_client *client)
350 {
351 struct pca955x_led *pca955x = i2c_get_clientdata(client);
352 int i;
353
354 for (i = 0; i < pca955x->chipdef->bits; i++) {
355 led_classdev_unregister(&pca955x[i].led_cdev);
356 cancel_work_sync(&pca955x[i].work);
357 }
358
359 kfree(pca955x);
360
361 return 0;
362 }
363
364 static struct i2c_driver pca955x_driver = {
365 .driver = {
366 .name = "leds-pca955x",
367 .owner = THIS_MODULE,
368 },
369 .probe = pca955x_probe,
370 .remove = __devexit_p(pca955x_remove),
371 .id_table = pca955x_id,
372 };
373
374 module_i2c_driver(pca955x_driver);
375
376 MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>");
377 MODULE_DESCRIPTION("PCA955x LED driver");
378 MODULE_LICENSE("GPL v2");
379