xref: /openbmc/linux/drivers/leds/leds-pca955x.c (revision 9ac8d3fb)
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 
58 enum pca955x_type {
59 	pca9550,
60 	pca9551,
61 	pca9552,
62 	pca9553,
63 };
64 
65 struct 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 
71 static 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 
94 static const struct i2c_device_id pca955x_id[] = {
95 	{ "pca9550", pca9550 },
96 	{ "pca9551", pca9551 },
97 	{ "pca9552", pca9552 },
98 	{ "pca9553", pca9553 },
99 	{ }
100 };
101 MODULE_DEVICE_TABLE(i2c, pca955x_id);
102 
103 struct 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 */
115 static inline int pca95xx_num_input_regs(int bits)
116 {
117 	return (bits + 7) / 8;
118 }
119 
120 /* 4 bits per LED selector register */
121 static 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  */
130 static 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  */
140 static 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  */
156 static 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  */
169 static 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  */
182 static 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 
190 static 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 
229 static void 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 
247 static int __devinit pca955x_probe(struct i2c_client *client,
248 					const struct i2c_device_id *id)
249 {
250 	struct pca955x_led *pca955x;
251 	struct pca955x_chipdef *chip;
252 	struct i2c_adapter *adapter;
253 	struct led_platform_data *pdata;
254 	int i, err;
255 
256 	chip = &pca955x_chipdefs[id->driver_data];
257 	adapter = to_i2c_adapter(client->dev.parent);
258 	pdata = client->dev.platform_data;
259 
260 	/* Make sure the slave address / chip type combo given is possible */
261 	if ((client->addr & ~((1 << chip->slv_addr_shift) - 1)) !=
262 	    chip->slv_addr) {
263 		dev_err(&client->dev, "invalid slave address %02x\n",
264 				client->addr);
265 		return -ENODEV;
266 	}
267 
268 	printk(KERN_INFO "leds-pca955x: Using %s %d-bit LED driver at "
269 			"slave address 0x%02x\n",
270 			id->name, chip->bits, client->addr);
271 
272 	if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
273 		return -EIO;
274 
275 	if (pdata) {
276 		if (pdata->num_leds != chip->bits) {
277 			dev_err(&client->dev, "board info claims %d LEDs"
278 					" on a %d-bit chip\n",
279 					pdata->num_leds, chip->bits);
280 			return -ENODEV;
281 		}
282 	}
283 
284 	pca955x = kzalloc(sizeof(*pca955x) * chip->bits, GFP_KERNEL);
285 	if (!pca955x)
286 		return -ENOMEM;
287 
288 	i2c_set_clientdata(client, pca955x);
289 
290 	for (i = 0; i < chip->bits; i++) {
291 		pca955x[i].chipdef = chip;
292 		pca955x[i].client = client;
293 		pca955x[i].led_num = i;
294 
295 		/* Platform data can specify LED names and default triggers */
296 		if (pdata) {
297 			if (pdata->leds[i].name)
298 				snprintf(pca955x[i].name,
299 					 sizeof(pca955x[i].name), "pca955x:%s",
300 					 pdata->leds[i].name);
301 			if (pdata->leds[i].default_trigger)
302 				pca955x[i].led_cdev.default_trigger =
303 					pdata->leds[i].default_trigger;
304 		} else {
305 			snprintf(pca955x[i].name, sizeof(pca955x[i].name),
306 				 "pca955x:%d", i);
307 		}
308 
309 		spin_lock_init(&pca955x[i].lock);
310 
311 		pca955x[i].led_cdev.name = pca955x[i].name;
312 		pca955x[i].led_cdev.brightness_set = pca955x_led_set;
313 
314 		INIT_WORK(&pca955x[i].work, pca955x_led_work);
315 
316 		err = led_classdev_register(&client->dev, &pca955x[i].led_cdev);
317 		if (err < 0)
318 			goto exit;
319 	}
320 
321 	/* Turn off LEDs */
322 	for (i = 0; i < pca95xx_num_led_regs(chip->bits); i++)
323 		pca955x_write_ls(client, i, 0x55);
324 
325 	/* PWM0 is used for half brightness or 50% duty cycle */
326 	pca955x_write_pwm(client, 0, 255-LED_HALF);
327 
328 	/* PWM1 is used for variable brightness, default to OFF */
329 	pca955x_write_pwm(client, 1, 0);
330 
331 	/* Set to fast frequency so we do not see flashing */
332 	pca955x_write_psc(client, 0, 0);
333 	pca955x_write_psc(client, 1, 0);
334 
335 	return 0;
336 
337 exit:
338 	while (i--) {
339 		led_classdev_unregister(&pca955x[i].led_cdev);
340 		cancel_work_sync(&pca955x[i].work);
341 	}
342 
343 	kfree(pca955x);
344 	i2c_set_clientdata(client, NULL);
345 
346 	return err;
347 }
348 
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 	i2c_set_clientdata(client, NULL);
361 
362 	return 0;
363 }
364 
365 static struct i2c_driver pca955x_driver = {
366 	.driver = {
367 		.name	= "leds-pca955x",
368 		.owner	= THIS_MODULE,
369 	},
370 	.probe	= pca955x_probe,
371 	.remove	= __devexit_p(pca955x_remove),
372 	.id_table = pca955x_id,
373 };
374 
375 static int __init pca955x_leds_init(void)
376 {
377 	return i2c_add_driver(&pca955x_driver);
378 }
379 
380 static void __exit pca955x_leds_exit(void)
381 {
382 	i2c_del_driver(&pca955x_driver);
383 }
384 
385 module_init(pca955x_leds_init);
386 module_exit(pca955x_leds_exit);
387 
388 MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>");
389 MODULE_DESCRIPTION("PCA955x LED driver");
390 MODULE_LICENSE("GPL v2");
391