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_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 */
116static inline int pca95xx_num_input_regs(int bits)
117{
118	return (bits + 7) / 8;
119}
120
121/* 4 bits per LED selector register */
122static 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 */
131static 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 */
141static 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 */
157static 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 */
170static 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 */
183static 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
191static 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
230static 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
248static 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
338exit:
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
349static 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
364static 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
374module_i2c_driver(pca955x_driver);
375
376MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>");
377MODULE_DESCRIPTION("PCA955x LED driver");
378MODULE_LICENSE("GPL v2");
379