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 = 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_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