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 {
105 struct mutex lock;
106 struct pca955x_led *leds;
107 struct pca955x_chipdef *chipdef;
108 struct i2c_client *client;
109 };
110
111 struct 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 */
pca95xx_num_input_regs(int bits)121 static inline int pca95xx_num_input_regs(int bits)
122 {
123 return (bits + 7) / 8;
124 }
125
126 /* 4 bits per LED selector register */
pca95xx_num_led_regs(int bits)127 static 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 */
pca955x_ledsel(u8 oldval,int led_num,int state)136 static 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 */
pca955x_write_psc(struct i2c_client * client,int n,u8 val)146 static 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 */
pca955x_write_pwm(struct i2c_client * client,int n,u8 val)162 static 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 */
pca955x_write_ls(struct i2c_client * client,int n,u8 val)175 static 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 */
pca955x_read_ls(struct i2c_client * client,int n)188 static 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
pca955x_led_work(struct work_struct * work)196 static 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
pca955x_led_set(struct led_classdev * led_cdev,enum led_brightness value)243 static 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
pca955x_probe(struct i2c_client * client,const struct i2c_device_id * id)258 static 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 = dev_get_platdata(&client->dev);
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_SMBUS_BYTE_DATA))
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
357 exit:
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
pca955x_remove(struct i2c_client * client)366 static 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
379 static struct i2c_driver pca955x_driver = {
380 .driver = {
381 .name = "leds-pca955x",
382 },
383 .probe = pca955x_probe,
384 .remove = pca955x_remove,
385 .id_table = pca955x_id,
386 };
387
388 module_i2c_driver(pca955x_driver);
389
390 MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>");
391 MODULE_DESCRIPTION("PCA955x LED driver");
392 MODULE_LICENSE("GPL v2");
393