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 
38 enum 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  */
49 struct ad7887_chip_info {
50 	u16				int_vref_mv;
51 	struct iio_chan_spec		channel[3];
52 };
53 
54 struct 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 
73 enum ad7887_supported_device_ids {
74 	ID_AD7887
75 };
76 
ad7887_ring_preenable(struct iio_dev * indio_dev)77 static 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 
ad7887_ring_postdisable(struct iio_dev * indio_dev)99 static 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  **/
ad7887_trigger_handler(int irq,void * p)113 static 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(indio_dev));
126 done:
127 	iio_trigger_notify_done(indio_dev->trig);
128 
129 	return IRQ_HANDLED;
130 }
131 
132 static 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 
ad7887_scan_direct(struct ad7887_state * st,unsigned ch)139 static 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 
ad7887_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long m)148 static 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 		ret = iio_device_claim_direct_mode(indio_dev);
160 		if (ret)
161 			return ret;
162 		ret = ad7887_scan_direct(st, chan->address);
163 		iio_device_release_direct_mode(indio_dev);
164 
165 		if (ret < 0)
166 			return ret;
167 		*val = ret >> chan->scan_type.shift;
168 		*val &= GENMASK(chan->scan_type.realbits - 1, 0);
169 		return IIO_VAL_INT;
170 	case IIO_CHAN_INFO_SCALE:
171 		if (st->reg) {
172 			*val = regulator_get_voltage(st->reg);
173 			if (*val < 0)
174 				return *val;
175 			*val /= 1000;
176 		} else {
177 			*val = st->chip_info->int_vref_mv;
178 		}
179 
180 		*val2 = chan->scan_type.realbits;
181 
182 		return IIO_VAL_FRACTIONAL_LOG2;
183 	}
184 	return -EINVAL;
185 }
186 
187 
188 static const struct ad7887_chip_info ad7887_chip_info_tbl[] = {
189 	/*
190 	 * More devices added in future
191 	 */
192 	[ID_AD7887] = {
193 		.channel[0] = {
194 			.type = IIO_VOLTAGE,
195 			.indexed = 1,
196 			.channel = 1,
197 			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
198 			.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
199 			.address = 1,
200 			.scan_index = 1,
201 			.scan_type = {
202 				.sign = 'u',
203 				.realbits = 12,
204 				.storagebits = 16,
205 				.shift = 0,
206 				.endianness = IIO_BE,
207 			},
208 		},
209 		.channel[1] = {
210 			.type = IIO_VOLTAGE,
211 			.indexed = 1,
212 			.channel = 0,
213 			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
214 			.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
215 			.address = 0,
216 			.scan_index = 0,
217 			.scan_type = {
218 				.sign = 'u',
219 				.realbits = 12,
220 				.storagebits = 16,
221 				.shift = 0,
222 				.endianness = IIO_BE,
223 			},
224 		},
225 		.channel[2] = IIO_CHAN_SOFT_TIMESTAMP(2),
226 		.int_vref_mv = 2500,
227 	},
228 };
229 
230 static const struct iio_info ad7887_info = {
231 	.read_raw = &ad7887_read_raw,
232 };
233 
ad7887_probe(struct spi_device * spi)234 static int ad7887_probe(struct spi_device *spi)
235 {
236 	struct ad7887_platform_data *pdata = spi->dev.platform_data;
237 	struct ad7887_state *st;
238 	struct iio_dev *indio_dev;
239 	uint8_t mode;
240 	int ret;
241 
242 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
243 	if (indio_dev == NULL)
244 		return -ENOMEM;
245 
246 	st = iio_priv(indio_dev);
247 
248 	if (!pdata || !pdata->use_onchip_ref) {
249 		st->reg = devm_regulator_get(&spi->dev, "vref");
250 		if (IS_ERR(st->reg))
251 			return PTR_ERR(st->reg);
252 
253 		ret = regulator_enable(st->reg);
254 		if (ret)
255 			return ret;
256 	}
257 
258 	st->chip_info =
259 		&ad7887_chip_info_tbl[spi_get_device_id(spi)->driver_data];
260 
261 	spi_set_drvdata(spi, indio_dev);
262 	st->spi = spi;
263 
264 	/* Estabilish that the iio_dev is a child of the spi device */
265 	indio_dev->dev.parent = &spi->dev;
266 	indio_dev->dev.of_node = spi->dev.of_node;
267 	indio_dev->name = spi_get_device_id(spi)->name;
268 	indio_dev->info = &ad7887_info;
269 	indio_dev->modes = INDIO_DIRECT_MODE;
270 
271 	/* Setup default message */
272 
273 	mode = AD7887_PM_MODE4;
274 	if (!pdata || !pdata->use_onchip_ref)
275 		mode |= AD7887_REF_DIS;
276 	if (pdata && pdata->en_dual)
277 		mode |= AD7887_DUAL;
278 
279 	st->tx_cmd_buf[0] = AD7887_CH_AIN0 | mode;
280 
281 	st->xfer[0].rx_buf = &st->data[0];
282 	st->xfer[0].tx_buf = &st->tx_cmd_buf[0];
283 	st->xfer[0].len = 2;
284 
285 	spi_message_init(&st->msg[AD7887_CH0]);
286 	spi_message_add_tail(&st->xfer[0], &st->msg[AD7887_CH0]);
287 
288 	if (pdata && pdata->en_dual) {
289 		st->tx_cmd_buf[2] = AD7887_CH_AIN1 | mode;
290 
291 		st->xfer[1].rx_buf = &st->data[0];
292 		st->xfer[1].tx_buf = &st->tx_cmd_buf[2];
293 		st->xfer[1].len = 2;
294 
295 		st->xfer[2].rx_buf = &st->data[2];
296 		st->xfer[2].tx_buf = &st->tx_cmd_buf[0];
297 		st->xfer[2].len = 2;
298 
299 		spi_message_init(&st->msg[AD7887_CH0_CH1]);
300 		spi_message_add_tail(&st->xfer[1], &st->msg[AD7887_CH0_CH1]);
301 		spi_message_add_tail(&st->xfer[2], &st->msg[AD7887_CH0_CH1]);
302 
303 		st->xfer[3].rx_buf = &st->data[2];
304 		st->xfer[3].tx_buf = &st->tx_cmd_buf[2];
305 		st->xfer[3].len = 2;
306 
307 		spi_message_init(&st->msg[AD7887_CH1]);
308 		spi_message_add_tail(&st->xfer[3], &st->msg[AD7887_CH1]);
309 
310 		indio_dev->channels = st->chip_info->channel;
311 		indio_dev->num_channels = 3;
312 	} else {
313 		indio_dev->channels = &st->chip_info->channel[1];
314 		indio_dev->num_channels = 2;
315 	}
316 
317 	ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
318 			&ad7887_trigger_handler, &ad7887_ring_setup_ops);
319 	if (ret)
320 		goto error_disable_reg;
321 
322 	ret = iio_device_register(indio_dev);
323 	if (ret)
324 		goto error_unregister_ring;
325 
326 	return 0;
327 error_unregister_ring:
328 	iio_triggered_buffer_cleanup(indio_dev);
329 error_disable_reg:
330 	if (st->reg)
331 		regulator_disable(st->reg);
332 
333 	return ret;
334 }
335 
ad7887_remove(struct spi_device * spi)336 static int ad7887_remove(struct spi_device *spi)
337 {
338 	struct iio_dev *indio_dev = spi_get_drvdata(spi);
339 	struct ad7887_state *st = iio_priv(indio_dev);
340 
341 	iio_device_unregister(indio_dev);
342 	iio_triggered_buffer_cleanup(indio_dev);
343 	if (st->reg)
344 		regulator_disable(st->reg);
345 
346 	return 0;
347 }
348 
349 static const struct spi_device_id ad7887_id[] = {
350 	{"ad7887", ID_AD7887},
351 	{}
352 };
353 MODULE_DEVICE_TABLE(spi, ad7887_id);
354 
355 static struct spi_driver ad7887_driver = {
356 	.driver = {
357 		.name	= "ad7887",
358 	},
359 	.probe		= ad7887_probe,
360 	.remove		= ad7887_remove,
361 	.id_table	= ad7887_id,
362 };
363 module_spi_driver(ad7887_driver);
364 
365 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
366 MODULE_DESCRIPTION("Analog Devices AD7887 ADC");
367 MODULE_LICENSE("GPL v2");
368