1/*
2 * AD7887 SPI ADC driver
3 *
4 * Copyright 2010-2011 Analog Devices Inc.
5 *
6 * Licensed under the GPL-2.
7 */
8
9#include <linux/device.h>
10#include <linux/kernel.h>
11#include <linux/slab.h>
12#include <linux/sysfs.h>
13#include <linux/spi/spi.h>
14#include <linux/regulator/consumer.h>
15#include <linux/err.h>
16#include <linux/module.h>
17#include <linux/interrupt.h>
18#include <linux/bitops.h>
19
20#include <linux/iio/iio.h>
21#include <linux/iio/sysfs.h>
22#include <linux/iio/buffer.h>
23
24#include <linux/iio/trigger_consumer.h>
25#include <linux/iio/triggered_buffer.h>
26
27#include <linux/platform_data/ad7887.h>
28
29#define AD7887_REF_DIS		BIT(5)	/* on-chip reference disable */
30#define AD7887_DUAL		BIT(4)	/* dual-channel mode */
31#define AD7887_CH_AIN1		BIT(3)	/* convert on channel 1, DUAL=1 */
32#define AD7887_CH_AIN0		0	/* convert on channel 0, DUAL=0,1 */
33#define AD7887_PM_MODE1		0	/* CS based shutdown */
34#define AD7887_PM_MODE2		1	/* full on */
35#define AD7887_PM_MODE3		2	/* auto shutdown after conversion */
36#define AD7887_PM_MODE4		3	/* standby mode */
37
38enum ad7887_channels {
39	AD7887_CH0,
40	AD7887_CH0_CH1,
41	AD7887_CH1,
42};
43
44/**
45 * struct ad7887_chip_info - chip specifc information
46 * @int_vref_mv:	the internal reference voltage
47 * @channel:		channel specification
48 */
49struct ad7887_chip_info {
50	u16				int_vref_mv;
51	struct iio_chan_spec		channel[3];
52};
53
54struct ad7887_state {
55	struct spi_device		*spi;
56	const struct ad7887_chip_info	*chip_info;
57	struct regulator		*reg;
58	struct spi_transfer		xfer[4];
59	struct spi_message		msg[3];
60	struct spi_message		*ring_msg;
61	unsigned char			tx_cmd_buf[4];
62
63	/*
64	 * DMA (thus cache coherency maintenance) requires the
65	 * transfer buffers to live in their own cache lines.
66	 * Buffer needs to be large enough to hold two 16 bit samples and a
67	 * 64 bit aligned 64 bit timestamp.
68	 */
69	unsigned char data[ALIGN(4, sizeof(s64)) + sizeof(s64)]
70		____cacheline_aligned;
71};
72
73enum ad7887_supported_device_ids {
74	ID_AD7887
75};
76
77static int ad7887_ring_preenable(struct iio_dev *indio_dev)
78{
79	struct ad7887_state *st = iio_priv(indio_dev);
80
81	/* We know this is a single long so can 'cheat' */
82	switch (*indio_dev->active_scan_mask) {
83	case (1 << 0):
84		st->ring_msg = &st->msg[AD7887_CH0];
85		break;
86	case (1 << 1):
87		st->ring_msg = &st->msg[AD7887_CH1];
88		/* Dummy read: push CH1 setting down to hardware */
89		spi_sync(st->spi, st->ring_msg);
90		break;
91	case ((1 << 1) | (1 << 0)):
92		st->ring_msg = &st->msg[AD7887_CH0_CH1];
93		break;
94	}
95
96	return 0;
97}
98
99static int ad7887_ring_postdisable(struct iio_dev *indio_dev)
100{
101	struct ad7887_state *st = iio_priv(indio_dev);
102
103	/* dummy read: restore default CH0 settin */
104	return spi_sync(st->spi, &st->msg[AD7887_CH0]);
105}
106
107/**
108 * ad7887_trigger_handler() bh of trigger launched polling to ring buffer
109 *
110 * Currently there is no option in this driver to disable the saving of
111 * timestamps within the ring.
112 **/
113static irqreturn_t ad7887_trigger_handler(int irq, void *p)
114{
115	struct iio_poll_func *pf = p;
116	struct iio_dev *indio_dev = pf->indio_dev;
117	struct ad7887_state *st = iio_priv(indio_dev);
118	int b_sent;
119
120	b_sent = spi_sync(st->spi, st->ring_msg);
121	if (b_sent)
122		goto done;
123
124	iio_push_to_buffers_with_timestamp(indio_dev, st->data,
125		iio_get_time_ns());
126done:
127	iio_trigger_notify_done(indio_dev->trig);
128
129	return IRQ_HANDLED;
130}
131
132static const struct iio_buffer_setup_ops ad7887_ring_setup_ops = {
133	.preenable = &ad7887_ring_preenable,
134	.postenable = &iio_triggered_buffer_postenable,
135	.predisable = &iio_triggered_buffer_predisable,
136	.postdisable = &ad7887_ring_postdisable,
137};
138
139static int ad7887_scan_direct(struct ad7887_state *st, unsigned ch)
140{
141	int ret = spi_sync(st->spi, &st->msg[ch]);
142	if (ret)
143		return ret;
144
145	return (st->data[(ch * 2)] << 8) | st->data[(ch * 2) + 1];
146}
147
148static int ad7887_read_raw(struct iio_dev *indio_dev,
149			   struct iio_chan_spec const *chan,
150			   int *val,
151			   int *val2,
152			   long m)
153{
154	int ret;
155	struct ad7887_state *st = iio_priv(indio_dev);
156
157	switch (m) {
158	case IIO_CHAN_INFO_RAW:
159		mutex_lock(&indio_dev->mlock);
160		if (iio_buffer_enabled(indio_dev))
161			ret = -EBUSY;
162		else
163			ret = ad7887_scan_direct(st, chan->address);
164		mutex_unlock(&indio_dev->mlock);
165
166		if (ret < 0)
167			return ret;
168		*val = ret >> chan->scan_type.shift;
169		*val &= GENMASK(chan->scan_type.realbits - 1, 0);
170		return IIO_VAL_INT;
171	case IIO_CHAN_INFO_SCALE:
172		if (st->reg) {
173			*val = regulator_get_voltage(st->reg);
174			if (*val < 0)
175				return *val;
176			*val /= 1000;
177		} else {
178			*val = st->chip_info->int_vref_mv;
179		}
180
181		*val2 = chan->scan_type.realbits;
182
183		return IIO_VAL_FRACTIONAL_LOG2;
184	}
185	return -EINVAL;
186}
187
188
189static const struct ad7887_chip_info ad7887_chip_info_tbl[] = {
190	/*
191	 * More devices added in future
192	 */
193	[ID_AD7887] = {
194		.channel[0] = {
195			.type = IIO_VOLTAGE,
196			.indexed = 1,
197			.channel = 1,
198			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
199			.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
200			.address = 1,
201			.scan_index = 1,
202			.scan_type = {
203				.sign = 'u',
204				.realbits = 12,
205				.storagebits = 16,
206				.shift = 0,
207				.endianness = IIO_BE,
208			},
209		},
210		.channel[1] = {
211			.type = IIO_VOLTAGE,
212			.indexed = 1,
213			.channel = 0,
214			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
215			.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
216			.address = 0,
217			.scan_index = 0,
218			.scan_type = {
219				.sign = 'u',
220				.realbits = 12,
221				.storagebits = 16,
222				.shift = 0,
223				.endianness = IIO_BE,
224			},
225		},
226		.channel[2] = IIO_CHAN_SOFT_TIMESTAMP(2),
227		.int_vref_mv = 2500,
228	},
229};
230
231static const struct iio_info ad7887_info = {
232	.read_raw = &ad7887_read_raw,
233	.driver_module = THIS_MODULE,
234};
235
236static int ad7887_probe(struct spi_device *spi)
237{
238	struct ad7887_platform_data *pdata = spi->dev.platform_data;
239	struct ad7887_state *st;
240	struct iio_dev *indio_dev;
241	uint8_t mode;
242	int ret;
243
244	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
245	if (indio_dev == NULL)
246		return -ENOMEM;
247
248	st = iio_priv(indio_dev);
249
250	if (!pdata || !pdata->use_onchip_ref) {
251		st->reg = devm_regulator_get(&spi->dev, "vref");
252		if (IS_ERR(st->reg))
253			return PTR_ERR(st->reg);
254
255		ret = regulator_enable(st->reg);
256		if (ret)
257			return ret;
258	}
259
260	st->chip_info =
261		&ad7887_chip_info_tbl[spi_get_device_id(spi)->driver_data];
262
263	spi_set_drvdata(spi, indio_dev);
264	st->spi = spi;
265
266	/* Estabilish that the iio_dev is a child of the spi device */
267	indio_dev->dev.parent = &spi->dev;
268	indio_dev->name = spi_get_device_id(spi)->name;
269	indio_dev->info = &ad7887_info;
270	indio_dev->modes = INDIO_DIRECT_MODE;
271
272	/* Setup default message */
273
274	mode = AD7887_PM_MODE4;
275	if (!pdata || !pdata->use_onchip_ref)
276		mode |= AD7887_REF_DIS;
277	if (pdata && pdata->en_dual)
278		mode |= AD7887_DUAL;
279
280	st->tx_cmd_buf[0] = AD7887_CH_AIN0 | mode;
281
282	st->xfer[0].rx_buf = &st->data[0];
283	st->xfer[0].tx_buf = &st->tx_cmd_buf[0];
284	st->xfer[0].len = 2;
285
286	spi_message_init(&st->msg[AD7887_CH0]);
287	spi_message_add_tail(&st->xfer[0], &st->msg[AD7887_CH0]);
288
289	if (pdata && pdata->en_dual) {
290		st->tx_cmd_buf[2] = AD7887_CH_AIN1 | mode;
291
292		st->xfer[1].rx_buf = &st->data[0];
293		st->xfer[1].tx_buf = &st->tx_cmd_buf[2];
294		st->xfer[1].len = 2;
295
296		st->xfer[2].rx_buf = &st->data[2];
297		st->xfer[2].tx_buf = &st->tx_cmd_buf[0];
298		st->xfer[2].len = 2;
299
300		spi_message_init(&st->msg[AD7887_CH0_CH1]);
301		spi_message_add_tail(&st->xfer[1], &st->msg[AD7887_CH0_CH1]);
302		spi_message_add_tail(&st->xfer[2], &st->msg[AD7887_CH0_CH1]);
303
304		st->xfer[3].rx_buf = &st->data[2];
305		st->xfer[3].tx_buf = &st->tx_cmd_buf[2];
306		st->xfer[3].len = 2;
307
308		spi_message_init(&st->msg[AD7887_CH1]);
309		spi_message_add_tail(&st->xfer[3], &st->msg[AD7887_CH1]);
310
311		indio_dev->channels = st->chip_info->channel;
312		indio_dev->num_channels = 3;
313	} else {
314		indio_dev->channels = &st->chip_info->channel[1];
315		indio_dev->num_channels = 2;
316	}
317
318	ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
319			&ad7887_trigger_handler, &ad7887_ring_setup_ops);
320	if (ret)
321		goto error_disable_reg;
322
323	ret = iio_device_register(indio_dev);
324	if (ret)
325		goto error_unregister_ring;
326
327	return 0;
328error_unregister_ring:
329	iio_triggered_buffer_cleanup(indio_dev);
330error_disable_reg:
331	if (st->reg)
332		regulator_disable(st->reg);
333
334	return ret;
335}
336
337static int ad7887_remove(struct spi_device *spi)
338{
339	struct iio_dev *indio_dev = spi_get_drvdata(spi);
340	struct ad7887_state *st = iio_priv(indio_dev);
341
342	iio_device_unregister(indio_dev);
343	iio_triggered_buffer_cleanup(indio_dev);
344	if (st->reg)
345		regulator_disable(st->reg);
346
347	return 0;
348}
349
350static const struct spi_device_id ad7887_id[] = {
351	{"ad7887", ID_AD7887},
352	{}
353};
354MODULE_DEVICE_TABLE(spi, ad7887_id);
355
356static struct spi_driver ad7887_driver = {
357	.driver = {
358		.name	= "ad7887",
359		.owner	= THIS_MODULE,
360	},
361	.probe		= ad7887_probe,
362	.remove		= ad7887_remove,
363	.id_table	= ad7887_id,
364};
365module_spi_driver(ad7887_driver);
366
367MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
368MODULE_DESCRIPTION("Analog Devices AD7887 ADC");
369MODULE_LICENSE("GPL v2");
370