1/*
2 * AD7816 digital temperature sensor driver supporting AD7816/7/8
3 *
4 * Copyright 2010 Analog Devices Inc.
5 *
6 * Licensed under the GPL-2 or later.
7 */
8
9#include <linux/interrupt.h>
10#include <linux/gpio.h>
11#include <linux/device.h>
12#include <linux/kernel.h>
13#include <linux/slab.h>
14#include <linux/sysfs.h>
15#include <linux/list.h>
16#include <linux/spi/spi.h>
17#include <linux/module.h>
18
19#include <linux/iio/iio.h>
20#include <linux/iio/sysfs.h>
21#include <linux/iio/events.h>
22
23/*
24 * AD7816 config masks
25 */
26#define AD7816_FULL			0x1
27#define AD7816_PD			0x2
28#define AD7816_CS_MASK			0x7
29#define AD7816_CS_MAX			0x4
30
31/*
32 * AD7816 temperature masks
33 */
34#define AD7816_VALUE_OFFSET		6
35#define AD7816_BOUND_VALUE_BASE		0x8
36#define AD7816_BOUND_VALUE_MIN		-95
37#define AD7816_BOUND_VALUE_MAX		152
38#define AD7816_TEMP_FLOAT_OFFSET	2
39#define AD7816_TEMP_FLOAT_MASK		0x3
40
41
42/*
43 * struct ad7816_chip_info - chip specific information
44 */
45
46struct ad7816_chip_info {
47	struct spi_device *spi_dev;
48	u16 rdwr_pin;
49	u16 convert_pin;
50	u16 busy_pin;
51	u8  oti_data[AD7816_CS_MAX+1];
52	u8  channel_id;	/* 0 always be temperature */
53	u8  mode;
54};
55
56/*
57 * ad7816 data access by SPI
58 */
59static int ad7816_spi_read(struct ad7816_chip_info *chip, u16 *data)
60{
61	struct spi_device *spi_dev = chip->spi_dev;
62	int ret = 0;
63
64	gpio_set_value(chip->rdwr_pin, 1);
65	gpio_set_value(chip->rdwr_pin, 0);
66	ret = spi_write(spi_dev, &chip->channel_id, sizeof(chip->channel_id));
67	if (ret < 0) {
68		dev_err(&spi_dev->dev, "SPI channel setting error\n");
69		return ret;
70	}
71	gpio_set_value(chip->rdwr_pin, 1);
72
73
74	if (chip->mode == AD7816_PD) { /* operating mode 2 */
75		gpio_set_value(chip->convert_pin, 1);
76		gpio_set_value(chip->convert_pin, 0);
77	} else { /* operating mode 1 */
78		gpio_set_value(chip->convert_pin, 0);
79		gpio_set_value(chip->convert_pin, 1);
80	}
81
82	while (gpio_get_value(chip->busy_pin))
83		cpu_relax();
84
85	gpio_set_value(chip->rdwr_pin, 0);
86	gpio_set_value(chip->rdwr_pin, 1);
87	ret = spi_read(spi_dev, (u8 *)data, sizeof(*data));
88	if (ret < 0) {
89		dev_err(&spi_dev->dev, "SPI data read error\n");
90		return ret;
91	}
92
93	*data = be16_to_cpu(*data);
94
95	return ret;
96}
97
98static int ad7816_spi_write(struct ad7816_chip_info *chip, u8 data)
99{
100	struct spi_device *spi_dev = chip->spi_dev;
101	int ret = 0;
102
103	gpio_set_value(chip->rdwr_pin, 1);
104	gpio_set_value(chip->rdwr_pin, 0);
105	ret = spi_write(spi_dev, &data, sizeof(data));
106	if (ret < 0)
107		dev_err(&spi_dev->dev, "SPI oti data write error\n");
108
109	return ret;
110}
111
112static ssize_t ad7816_show_mode(struct device *dev,
113		struct device_attribute *attr,
114		char *buf)
115{
116	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
117	struct ad7816_chip_info *chip = iio_priv(indio_dev);
118
119	if (chip->mode)
120		return sprintf(buf, "power-save\n");
121	return sprintf(buf, "full\n");
122}
123
124static ssize_t ad7816_store_mode(struct device *dev,
125		struct device_attribute *attr,
126		const char *buf,
127		size_t len)
128{
129	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
130	struct ad7816_chip_info *chip = iio_priv(indio_dev);
131
132	if (strcmp(buf, "full")) {
133		gpio_set_value(chip->rdwr_pin, 1);
134		chip->mode = AD7816_FULL;
135	} else {
136		gpio_set_value(chip->rdwr_pin, 0);
137		chip->mode = AD7816_PD;
138	}
139
140	return len;
141}
142
143static IIO_DEVICE_ATTR(mode, S_IRUGO | S_IWUSR,
144		ad7816_show_mode,
145		ad7816_store_mode,
146		0);
147
148static ssize_t ad7816_show_available_modes(struct device *dev,
149		struct device_attribute *attr,
150		char *buf)
151{
152	return sprintf(buf, "full\npower-save\n");
153}
154
155static IIO_DEVICE_ATTR(available_modes, S_IRUGO, ad7816_show_available_modes,
156			NULL, 0);
157
158static ssize_t ad7816_show_channel(struct device *dev,
159		struct device_attribute *attr,
160		char *buf)
161{
162	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
163	struct ad7816_chip_info *chip = iio_priv(indio_dev);
164
165	return sprintf(buf, "%d\n", chip->channel_id);
166}
167
168static ssize_t ad7816_store_channel(struct device *dev,
169		struct device_attribute *attr,
170		const char *buf,
171		size_t len)
172{
173	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
174	struct ad7816_chip_info *chip = iio_priv(indio_dev);
175	unsigned long data;
176	int ret;
177
178	ret = kstrtoul(buf, 10, &data);
179	if (ret)
180		return ret;
181
182	if (data > AD7816_CS_MAX && data != AD7816_CS_MASK) {
183		dev_err(&chip->spi_dev->dev, "Invalid channel id %lu for %s.\n",
184			data, indio_dev->name);
185		return -EINVAL;
186	} else if (strcmp(indio_dev->name, "ad7818") == 0 && data > 1) {
187		dev_err(&chip->spi_dev->dev,
188			"Invalid channel id %lu for ad7818.\n", data);
189		return -EINVAL;
190	} else if (strcmp(indio_dev->name, "ad7816") == 0 && data > 0) {
191		dev_err(&chip->spi_dev->dev,
192			"Invalid channel id %lu for ad7816.\n", data);
193		return -EINVAL;
194	}
195
196	chip->channel_id = data;
197
198	return len;
199}
200
201static IIO_DEVICE_ATTR(channel, S_IRUGO | S_IWUSR,
202		ad7816_show_channel,
203		ad7816_store_channel,
204		0);
205
206
207static ssize_t ad7816_show_value(struct device *dev,
208		struct device_attribute *attr,
209		char *buf)
210{
211	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
212	struct ad7816_chip_info *chip = iio_priv(indio_dev);
213	u16 data;
214	s8 value;
215	int ret;
216
217	ret = ad7816_spi_read(chip, &data);
218	if (ret)
219		return -EIO;
220
221	data >>= AD7816_VALUE_OFFSET;
222
223	if (chip->channel_id == 0) {
224		value = (s8)((data >> AD7816_TEMP_FLOAT_OFFSET) - 103);
225		data &= AD7816_TEMP_FLOAT_MASK;
226		if (value < 0)
227			data = (1 << AD7816_TEMP_FLOAT_OFFSET) - data;
228		return sprintf(buf, "%d.%.2d\n", value, data * 25);
229	}
230	return sprintf(buf, "%u\n", data);
231}
232
233static IIO_DEVICE_ATTR(value, S_IRUGO, ad7816_show_value, NULL, 0);
234
235static struct attribute *ad7816_attributes[] = {
236	&iio_dev_attr_available_modes.dev_attr.attr,
237	&iio_dev_attr_mode.dev_attr.attr,
238	&iio_dev_attr_channel.dev_attr.attr,
239	&iio_dev_attr_value.dev_attr.attr,
240	NULL,
241};
242
243static const struct attribute_group ad7816_attribute_group = {
244	.attrs = ad7816_attributes,
245};
246
247/*
248 * temperature bound events
249 */
250
251#define IIO_EVENT_CODE_AD7816_OTI IIO_UNMOD_EVENT_CODE(IIO_TEMP,	\
252						       0,		\
253						       IIO_EV_TYPE_THRESH, \
254						       IIO_EV_DIR_FALLING)
255
256static irqreturn_t ad7816_event_handler(int irq, void *private)
257{
258	iio_push_event(private, IIO_EVENT_CODE_AD7816_OTI, iio_get_time_ns());
259	return IRQ_HANDLED;
260}
261
262static ssize_t ad7816_show_oti(struct device *dev,
263		struct device_attribute *attr,
264		char *buf)
265{
266	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
267	struct ad7816_chip_info *chip = iio_priv(indio_dev);
268	int value;
269
270	if (chip->channel_id > AD7816_CS_MAX) {
271		dev_err(dev, "Invalid oti channel id %d.\n", chip->channel_id);
272		return -EINVAL;
273	} else if (chip->channel_id == 0) {
274		value = AD7816_BOUND_VALUE_MIN +
275			(chip->oti_data[chip->channel_id] -
276			AD7816_BOUND_VALUE_BASE);
277		return sprintf(buf, "%d\n", value);
278	}
279	return sprintf(buf, "%u\n", chip->oti_data[chip->channel_id]);
280}
281
282static inline ssize_t ad7816_set_oti(struct device *dev,
283		struct device_attribute *attr,
284		const char *buf,
285		size_t len)
286{
287	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
288	struct ad7816_chip_info *chip = iio_priv(indio_dev);
289	long value;
290	u8 data;
291	int ret;
292
293	ret = kstrtol(buf, 10, &value);
294	if (ret)
295		return ret;
296
297	if (chip->channel_id > AD7816_CS_MAX) {
298		dev_err(dev, "Invalid oti channel id %d.\n", chip->channel_id);
299		return -EINVAL;
300	} else if (chip->channel_id == 0) {
301		if (ret || value < AD7816_BOUND_VALUE_MIN ||
302			value > AD7816_BOUND_VALUE_MAX)
303			return -EINVAL;
304
305		data = (u8)(value - AD7816_BOUND_VALUE_MIN +
306			AD7816_BOUND_VALUE_BASE);
307	} else {
308		if (ret || value < AD7816_BOUND_VALUE_BASE || value > 255)
309			return -EINVAL;
310
311		data = (u8)value;
312	}
313
314	ret = ad7816_spi_write(chip, data);
315	if (ret)
316		return -EIO;
317
318	chip->oti_data[chip->channel_id] = data;
319
320	return len;
321}
322
323static IIO_DEVICE_ATTR(oti, S_IRUGO | S_IWUSR,
324		       ad7816_show_oti, ad7816_set_oti, 0);
325
326static struct attribute *ad7816_event_attributes[] = {
327	&iio_dev_attr_oti.dev_attr.attr,
328	NULL,
329};
330
331static struct attribute_group ad7816_event_attribute_group = {
332	.attrs = ad7816_event_attributes,
333	.name = "events",
334};
335
336static const struct iio_info ad7816_info = {
337	.attrs = &ad7816_attribute_group,
338	.event_attrs = &ad7816_event_attribute_group,
339	.driver_module = THIS_MODULE,
340};
341
342/*
343 * device probe and remove
344 */
345
346static int ad7816_probe(struct spi_device *spi_dev)
347{
348	struct ad7816_chip_info *chip;
349	struct iio_dev *indio_dev;
350	unsigned short *pins = spi_dev->dev.platform_data;
351	int ret = 0;
352	int i;
353
354	if (!pins) {
355		dev_err(&spi_dev->dev, "No necessary GPIO platform data.\n");
356		return -EINVAL;
357	}
358
359	indio_dev = devm_iio_device_alloc(&spi_dev->dev, sizeof(*chip));
360	if (!indio_dev)
361		return -ENOMEM;
362	chip = iio_priv(indio_dev);
363	/* this is only used for device removal purposes */
364	dev_set_drvdata(&spi_dev->dev, indio_dev);
365
366	chip->spi_dev = spi_dev;
367	for (i = 0; i <= AD7816_CS_MAX; i++)
368		chip->oti_data[i] = 203;
369	chip->rdwr_pin = pins[0];
370	chip->convert_pin = pins[1];
371	chip->busy_pin = pins[2];
372
373	ret = devm_gpio_request(&spi_dev->dev, chip->rdwr_pin,
374					spi_get_device_id(spi_dev)->name);
375	if (ret) {
376		dev_err(&spi_dev->dev, "Fail to request rdwr gpio PIN %d.\n",
377			chip->rdwr_pin);
378		return ret;
379	}
380	gpio_direction_input(chip->rdwr_pin);
381	ret = devm_gpio_request(&spi_dev->dev, chip->convert_pin,
382					spi_get_device_id(spi_dev)->name);
383	if (ret) {
384		dev_err(&spi_dev->dev, "Fail to request convert gpio PIN %d.\n",
385			chip->convert_pin);
386		return ret;
387	}
388	gpio_direction_input(chip->convert_pin);
389	ret = devm_gpio_request(&spi_dev->dev, chip->busy_pin,
390					spi_get_device_id(spi_dev)->name);
391	if (ret) {
392		dev_err(&spi_dev->dev, "Fail to request busy gpio PIN %d.\n",
393			chip->busy_pin);
394		return ret;
395	}
396	gpio_direction_input(chip->busy_pin);
397
398	indio_dev->name = spi_get_device_id(spi_dev)->name;
399	indio_dev->dev.parent = &spi_dev->dev;
400	indio_dev->info = &ad7816_info;
401	indio_dev->modes = INDIO_DIRECT_MODE;
402
403	if (spi_dev->irq) {
404		/* Only low trigger is supported in ad7816/7/8 */
405		ret = devm_request_threaded_irq(&spi_dev->dev, spi_dev->irq,
406						NULL,
407						&ad7816_event_handler,
408						IRQF_TRIGGER_LOW | IRQF_ONESHOT,
409						indio_dev->name,
410						indio_dev);
411		if (ret)
412			return ret;
413	}
414
415	ret = devm_iio_device_register(&spi_dev->dev, indio_dev);
416	if (ret)
417		return ret;
418
419	dev_info(&spi_dev->dev, "%s temperature sensor and ADC registered.\n",
420			 indio_dev->name);
421
422	return 0;
423}
424
425static const struct spi_device_id ad7816_id[] = {
426	{ "ad7816", 0 },
427	{ "ad7817", 0 },
428	{ "ad7818", 0 },
429	{}
430};
431
432MODULE_DEVICE_TABLE(spi, ad7816_id);
433
434static struct spi_driver ad7816_driver = {
435	.driver = {
436		.name = "ad7816",
437		.owner = THIS_MODULE,
438	},
439	.probe = ad7816_probe,
440	.id_table = ad7816_id,
441};
442module_spi_driver(ad7816_driver);
443
444MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
445MODULE_DESCRIPTION("Analog Devices AD7816/7/8 digital temperature sensor driver");
446MODULE_LICENSE("GPL v2");
447