1/*
2 *  tsl2550.c - Linux kernel modules for ambient light sensor
3 *
4 *  Copyright (C) 2007 Rodolfo Giometti <giometti@linux.it>
5 *  Copyright (C) 2007 Eurotech S.p.A. <info@eurotech.it>
6 *
7 *  This program is free software; you can redistribute it and/or modify
8 *  it under the terms of the GNU General Public License as published by
9 *  the Free Software Foundation; either version 2 of the License, or
10 *  (at your option) any later version.
11 *
12 *  This program is distributed in the hope that it will be useful,
13 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
14 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 *  GNU General Public License for more details.
16 *
17 *  You should have received a copy of the GNU General Public License
18 *  along with this program; if not, write to the Free Software
19 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 */
21
22#include <linux/module.h>
23#include <linux/slab.h>
24#include <linux/i2c.h>
25#include <linux/mutex.h>
26
27#define TSL2550_DRV_NAME	"tsl2550"
28#define DRIVER_VERSION		"1.2"
29
30/*
31 * Defines
32 */
33
34#define TSL2550_POWER_DOWN		0x00
35#define TSL2550_POWER_UP		0x03
36#define TSL2550_STANDARD_RANGE		0x18
37#define TSL2550_EXTENDED_RANGE		0x1d
38#define TSL2550_READ_ADC0		0x43
39#define TSL2550_READ_ADC1		0x83
40
41/*
42 * Structs
43 */
44
45struct tsl2550_data {
46	struct i2c_client *client;
47	struct mutex update_lock;
48
49	unsigned int power_state:1;
50	unsigned int operating_mode:1;
51};
52
53/*
54 * Global data
55 */
56
57static const u8 TSL2550_MODE_RANGE[2] = {
58	TSL2550_STANDARD_RANGE, TSL2550_EXTENDED_RANGE,
59};
60
61/*
62 * Management functions
63 */
64
65static int tsl2550_set_operating_mode(struct i2c_client *client, int mode)
66{
67	struct tsl2550_data *data = i2c_get_clientdata(client);
68
69	int ret = i2c_smbus_write_byte(client, TSL2550_MODE_RANGE[mode]);
70
71	data->operating_mode = mode;
72
73	return ret;
74}
75
76static int tsl2550_set_power_state(struct i2c_client *client, int state)
77{
78	struct tsl2550_data *data = i2c_get_clientdata(client);
79	int ret;
80
81	if (state == 0)
82		ret = i2c_smbus_write_byte(client, TSL2550_POWER_DOWN);
83	else {
84		ret = i2c_smbus_write_byte(client, TSL2550_POWER_UP);
85
86		/* On power up we should reset operating mode also... */
87		tsl2550_set_operating_mode(client, data->operating_mode);
88	}
89
90	data->power_state = state;
91
92	return ret;
93}
94
95static int tsl2550_get_adc_value(struct i2c_client *client, u8 cmd)
96{
97	int ret;
98
99	ret = i2c_smbus_read_byte_data(client, cmd);
100	if (ret < 0)
101		return ret;
102	if (!(ret & 0x80))
103		return -EAGAIN;
104	return ret & 0x7f;	/* remove the "valid" bit */
105}
106
107/*
108 * LUX calculation
109 */
110
111#define	TSL2550_MAX_LUX		1846
112
113static const u8 ratio_lut[] = {
114	100, 100, 100, 100, 100, 100, 100, 100,
115	100, 100, 100, 100, 100, 100, 99, 99,
116	99, 99, 99, 99, 99, 99, 99, 99,
117	99, 99, 99, 98, 98, 98, 98, 98,
118	98, 98, 97, 97, 97, 97, 97, 96,
119	96, 96, 96, 95, 95, 95, 94, 94,
120	93, 93, 93, 92, 92, 91, 91, 90,
121	89, 89, 88, 87, 87, 86, 85, 84,
122	83, 82, 81, 80, 79, 78, 77, 75,
123	74, 73, 71, 69, 68, 66, 64, 62,
124	60, 58, 56, 54, 52, 49, 47, 44,
125	42, 41, 40, 40, 39, 39, 38, 38,
126	37, 37, 37, 36, 36, 36, 35, 35,
127	35, 35, 34, 34, 34, 34, 33, 33,
128	33, 33, 32, 32, 32, 32, 32, 31,
129	31, 31, 31, 31, 30, 30, 30, 30,
130	30,
131};
132
133static const u16 count_lut[] = {
134	0, 1, 2, 3, 4, 5, 6, 7,
135	8, 9, 10, 11, 12, 13, 14, 15,
136	16, 18, 20, 22, 24, 26, 28, 30,
137	32, 34, 36, 38, 40, 42, 44, 46,
138	49, 53, 57, 61, 65, 69, 73, 77,
139	81, 85, 89, 93, 97, 101, 105, 109,
140	115, 123, 131, 139, 147, 155, 163, 171,
141	179, 187, 195, 203, 211, 219, 227, 235,
142	247, 263, 279, 295, 311, 327, 343, 359,
143	375, 391, 407, 423, 439, 455, 471, 487,
144	511, 543, 575, 607, 639, 671, 703, 735,
145	767, 799, 831, 863, 895, 927, 959, 991,
146	1039, 1103, 1167, 1231, 1295, 1359, 1423, 1487,
147	1551, 1615, 1679, 1743, 1807, 1871, 1935, 1999,
148	2095, 2223, 2351, 2479, 2607, 2735, 2863, 2991,
149	3119, 3247, 3375, 3503, 3631, 3759, 3887, 4015,
150};
151
152/*
153 * This function is described into Taos TSL2550 Designer's Notebook
154 * pages 2, 3.
155 */
156static int tsl2550_calculate_lux(u8 ch0, u8 ch1)
157{
158	unsigned int lux;
159
160	/* Look up count from channel values */
161	u16 c0 = count_lut[ch0];
162	u16 c1 = count_lut[ch1];
163
164	/*
165	 * Calculate ratio.
166	 * Note: the "128" is a scaling factor
167	 */
168	u8 r = 128;
169
170	/* Avoid division by 0 and count 1 cannot be greater than count 0 */
171	if (c1 <= c0)
172		if (c0) {
173			r = c1 * 128 / c0;
174
175			/* Calculate LUX */
176			lux = ((c0 - c1) * ratio_lut[r]) / 256;
177		} else
178			lux = 0;
179	else
180		return -EAGAIN;
181
182	/* LUX range check */
183	return lux > TSL2550_MAX_LUX ? TSL2550_MAX_LUX : lux;
184}
185
186/*
187 * SysFS support
188 */
189
190static ssize_t tsl2550_show_power_state(struct device *dev,
191		struct device_attribute *attr, char *buf)
192{
193	struct tsl2550_data *data = i2c_get_clientdata(to_i2c_client(dev));
194
195	return sprintf(buf, "%u\n", data->power_state);
196}
197
198static ssize_t tsl2550_store_power_state(struct device *dev,
199		struct device_attribute *attr, const char *buf, size_t count)
200{
201	struct i2c_client *client = to_i2c_client(dev);
202	struct tsl2550_data *data = i2c_get_clientdata(client);
203	unsigned long val = simple_strtoul(buf, NULL, 10);
204	int ret;
205
206	if (val > 1)
207		return -EINVAL;
208
209	mutex_lock(&data->update_lock);
210	ret = tsl2550_set_power_state(client, val);
211	mutex_unlock(&data->update_lock);
212
213	if (ret < 0)
214		return ret;
215
216	return count;
217}
218
219static DEVICE_ATTR(power_state, S_IWUSR | S_IRUGO,
220		   tsl2550_show_power_state, tsl2550_store_power_state);
221
222static ssize_t tsl2550_show_operating_mode(struct device *dev,
223		struct device_attribute *attr, char *buf)
224{
225	struct tsl2550_data *data = i2c_get_clientdata(to_i2c_client(dev));
226
227	return sprintf(buf, "%u\n", data->operating_mode);
228}
229
230static ssize_t tsl2550_store_operating_mode(struct device *dev,
231		struct device_attribute *attr, const char *buf, size_t count)
232{
233	struct i2c_client *client = to_i2c_client(dev);
234	struct tsl2550_data *data = i2c_get_clientdata(client);
235	unsigned long val = simple_strtoul(buf, NULL, 10);
236	int ret;
237
238	if (val > 1)
239		return -EINVAL;
240
241	if (data->power_state == 0)
242		return -EBUSY;
243
244	mutex_lock(&data->update_lock);
245	ret = tsl2550_set_operating_mode(client, val);
246	mutex_unlock(&data->update_lock);
247
248	if (ret < 0)
249		return ret;
250
251	return count;
252}
253
254static DEVICE_ATTR(operating_mode, S_IWUSR | S_IRUGO,
255		   tsl2550_show_operating_mode, tsl2550_store_operating_mode);
256
257static ssize_t __tsl2550_show_lux(struct i2c_client *client, char *buf)
258{
259	struct tsl2550_data *data = i2c_get_clientdata(client);
260	u8 ch0, ch1;
261	int ret;
262
263	ret = tsl2550_get_adc_value(client, TSL2550_READ_ADC0);
264	if (ret < 0)
265		return ret;
266	ch0 = ret;
267
268	ret = tsl2550_get_adc_value(client, TSL2550_READ_ADC1);
269	if (ret < 0)
270		return ret;
271	ch1 = ret;
272
273	/* Do the job */
274	ret = tsl2550_calculate_lux(ch0, ch1);
275	if (ret < 0)
276		return ret;
277	if (data->operating_mode == 1)
278		ret *= 5;
279
280	return sprintf(buf, "%d\n", ret);
281}
282
283static ssize_t tsl2550_show_lux1_input(struct device *dev,
284			struct device_attribute *attr, char *buf)
285{
286	struct i2c_client *client = to_i2c_client(dev);
287	struct tsl2550_data *data = i2c_get_clientdata(client);
288	int ret;
289
290	/* No LUX data if not operational */
291	if (!data->power_state)
292		return -EBUSY;
293
294	mutex_lock(&data->update_lock);
295	ret = __tsl2550_show_lux(client, buf);
296	mutex_unlock(&data->update_lock);
297
298	return ret;
299}
300
301static DEVICE_ATTR(lux1_input, S_IRUGO,
302		   tsl2550_show_lux1_input, NULL);
303
304static struct attribute *tsl2550_attributes[] = {
305	&dev_attr_power_state.attr,
306	&dev_attr_operating_mode.attr,
307	&dev_attr_lux1_input.attr,
308	NULL
309};
310
311static const struct attribute_group tsl2550_attr_group = {
312	.attrs = tsl2550_attributes,
313};
314
315/*
316 * Initialization function
317 */
318
319static int tsl2550_init_client(struct i2c_client *client)
320{
321	struct tsl2550_data *data = i2c_get_clientdata(client);
322	int err;
323
324	/*
325	 * Probe the chip. To do so we try to power up the device and then to
326	 * read back the 0x03 code
327	 */
328	err = i2c_smbus_read_byte_data(client, TSL2550_POWER_UP);
329	if (err < 0)
330		return err;
331	if (err != TSL2550_POWER_UP)
332		return -ENODEV;
333	data->power_state = 1;
334
335	/* Set the default operating mode */
336	err = i2c_smbus_write_byte(client,
337				   TSL2550_MODE_RANGE[data->operating_mode]);
338	if (err < 0)
339		return err;
340
341	return 0;
342}
343
344/*
345 * I2C init/probing/exit functions
346 */
347
348static struct i2c_driver tsl2550_driver;
349static int tsl2550_probe(struct i2c_client *client,
350				   const struct i2c_device_id *id)
351{
352	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
353	struct tsl2550_data *data;
354	int *opmode, err = 0;
355
356	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE
357					    | I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
358		err = -EIO;
359		goto exit;
360	}
361
362	data = kzalloc(sizeof(struct tsl2550_data), GFP_KERNEL);
363	if (!data) {
364		err = -ENOMEM;
365		goto exit;
366	}
367	data->client = client;
368	i2c_set_clientdata(client, data);
369
370	/* Check platform data */
371	opmode = client->dev.platform_data;
372	if (opmode) {
373		if (*opmode < 0 || *opmode > 1) {
374			dev_err(&client->dev, "invalid operating_mode (%d)\n",
375					*opmode);
376			err = -EINVAL;
377			goto exit_kfree;
378		}
379		data->operating_mode = *opmode;
380	} else
381		data->operating_mode = 0;	/* default mode is standard */
382	dev_info(&client->dev, "%s operating mode\n",
383			data->operating_mode ? "extended" : "standard");
384
385	mutex_init(&data->update_lock);
386
387	/* Initialize the TSL2550 chip */
388	err = tsl2550_init_client(client);
389	if (err)
390		goto exit_kfree;
391
392	/* Register sysfs hooks */
393	err = sysfs_create_group(&client->dev.kobj, &tsl2550_attr_group);
394	if (err)
395		goto exit_kfree;
396
397	dev_info(&client->dev, "support ver. %s enabled\n", DRIVER_VERSION);
398
399	return 0;
400
401exit_kfree:
402	kfree(data);
403exit:
404	return err;
405}
406
407static int tsl2550_remove(struct i2c_client *client)
408{
409	sysfs_remove_group(&client->dev.kobj, &tsl2550_attr_group);
410
411	/* Power down the device */
412	tsl2550_set_power_state(client, 0);
413
414	kfree(i2c_get_clientdata(client));
415
416	return 0;
417}
418
419#ifdef CONFIG_PM_SLEEP
420
421static int tsl2550_suspend(struct device *dev)
422{
423	return tsl2550_set_power_state(to_i2c_client(dev), 0);
424}
425
426static int tsl2550_resume(struct device *dev)
427{
428	return tsl2550_set_power_state(to_i2c_client(dev), 1);
429}
430
431static SIMPLE_DEV_PM_OPS(tsl2550_pm_ops, tsl2550_suspend, tsl2550_resume);
432#define TSL2550_PM_OPS (&tsl2550_pm_ops)
433
434#else
435
436#define TSL2550_PM_OPS NULL
437
438#endif /* CONFIG_PM_SLEEP */
439
440static const struct i2c_device_id tsl2550_id[] = {
441	{ "tsl2550", 0 },
442	{ }
443};
444MODULE_DEVICE_TABLE(i2c, tsl2550_id);
445
446static struct i2c_driver tsl2550_driver = {
447	.driver = {
448		.name	= TSL2550_DRV_NAME,
449		.pm	= TSL2550_PM_OPS,
450	},
451	.probe	= tsl2550_probe,
452	.remove	= tsl2550_remove,
453	.id_table = tsl2550_id,
454};
455
456module_i2c_driver(tsl2550_driver);
457
458MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
459MODULE_DESCRIPTION("TSL2550 ambient light sensor driver");
460MODULE_LICENSE("GPL");
461MODULE_VERSION(DRIVER_VERSION);
462