1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * MAX1117/MAX1118/MAX1119 8-bit, dual-channel ADCs driver
4 *
5 * Copyright (c) 2017 Akinobu Mita <akinobu.mita@gmail.com>
6 *
7 * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1117-MAX1119.pdf
8 *
9 * SPI interface connections
10 *
11 * SPI                MAXIM
12 * Master  Direction  MAX1117/8/9
13 * ------  ---------  -----------
14 * nCS        -->     CNVST
15 * SCK        -->     SCLK
16 * MISO       <--     DOUT
17 * ------  ---------  -----------
18 */
19
20#include <linux/module.h>
21#include <linux/mod_devicetable.h>
22#include <linux/spi/spi.h>
23#include <linux/iio/iio.h>
24#include <linux/iio/buffer.h>
25#include <linux/iio/triggered_buffer.h>
26#include <linux/iio/trigger_consumer.h>
27#include <linux/regulator/consumer.h>
28
29enum max1118_id {
30	max1117,
31	max1118,
32	max1119,
33};
34
35struct max1118 {
36	struct spi_device *spi;
37	struct mutex lock;
38	struct regulator *reg;
39	/* Ensure natural alignment of buffer elements */
40	struct {
41		u8 channels[2];
42		s64 ts __aligned(8);
43	} scan;
44
45	u8 data __aligned(IIO_DMA_MINALIGN);
46};
47
48#define MAX1118_CHANNEL(ch)						\
49	{								\
50		.type = IIO_VOLTAGE,					\
51		.indexed = 1,						\
52		.channel = (ch),					\
53		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
54		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
55		.scan_index = ch,					\
56		.scan_type = {						\
57			.sign = 'u',					\
58			.realbits = 8,					\
59			.storagebits = 8,				\
60		},							\
61	}
62
63static const struct iio_chan_spec max1118_channels[] = {
64	MAX1118_CHANNEL(0),
65	MAX1118_CHANNEL(1),
66	IIO_CHAN_SOFT_TIMESTAMP(2),
67};
68
69static int max1118_read(struct iio_dev *indio_dev, int channel)
70{
71	struct max1118 *adc = iio_priv(indio_dev);
72	struct spi_transfer xfers[] = {
73		/*
74		 * To select CH1 for conversion, CNVST pin must be brought high
75		 * and low for a second time.
76		 */
77		{
78			.len = 0,
79			.delay = {	/* > CNVST Low Time 100 ns */
80				.value = 1,
81				.unit = SPI_DELAY_UNIT_USECS
82			},
83			.cs_change = 1,
84		},
85		/*
86		 * The acquisition interval begins with the falling edge of
87		 * CNVST.  The total acquisition and conversion process takes
88		 * <7.5us.
89		 */
90		{
91			.len = 0,
92			.delay = {
93				.value = 8,
94				.unit = SPI_DELAY_UNIT_USECS
95			},
96		},
97		{
98			.rx_buf = &adc->data,
99			.len = 1,
100		},
101	};
102	int ret;
103
104	if (channel == 0)
105		ret = spi_sync_transfer(adc->spi, xfers + 1, 2);
106	else
107		ret = spi_sync_transfer(adc->spi, xfers, 3);
108
109	if (ret)
110		return ret;
111
112	return adc->data;
113}
114
115static int max1118_get_vref_mV(struct iio_dev *indio_dev)
116{
117	struct max1118 *adc = iio_priv(indio_dev);
118	const struct spi_device_id *id = spi_get_device_id(adc->spi);
119	int vref_uV;
120
121	switch (id->driver_data) {
122	case max1117:
123		return 2048;
124	case max1119:
125		return 4096;
126	case max1118:
127		vref_uV = regulator_get_voltage(adc->reg);
128		if (vref_uV < 0)
129			return vref_uV;
130		return vref_uV / 1000;
131	}
132
133	return -ENODEV;
134}
135
136static int max1118_read_raw(struct iio_dev *indio_dev,
137			struct iio_chan_spec const *chan,
138			int *val, int *val2, long mask)
139{
140	struct max1118 *adc = iio_priv(indio_dev);
141
142	switch (mask) {
143	case IIO_CHAN_INFO_RAW:
144		mutex_lock(&adc->lock);
145		*val = max1118_read(indio_dev, chan->channel);
146		mutex_unlock(&adc->lock);
147		if (*val < 0)
148			return *val;
149
150		return IIO_VAL_INT;
151	case IIO_CHAN_INFO_SCALE:
152		*val = max1118_get_vref_mV(indio_dev);
153		if (*val < 0)
154			return *val;
155		*val2 = 8;
156
157		return IIO_VAL_FRACTIONAL_LOG2;
158	}
159
160	return -EINVAL;
161}
162
163static const struct iio_info max1118_info = {
164	.read_raw = max1118_read_raw,
165};
166
167static irqreturn_t max1118_trigger_handler(int irq, void *p)
168{
169	struct iio_poll_func *pf = p;
170	struct iio_dev *indio_dev = pf->indio_dev;
171	struct max1118 *adc = iio_priv(indio_dev);
172	int scan_index;
173	int i = 0;
174
175	mutex_lock(&adc->lock);
176
177	for_each_set_bit(scan_index, indio_dev->active_scan_mask,
178			indio_dev->masklength) {
179		const struct iio_chan_spec *scan_chan =
180				&indio_dev->channels[scan_index];
181		int ret = max1118_read(indio_dev, scan_chan->channel);
182
183		if (ret < 0) {
184			dev_warn(&adc->spi->dev,
185				"failed to get conversion data\n");
186			goto out;
187		}
188
189		adc->scan.channels[i] = ret;
190		i++;
191	}
192	iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,
193					   iio_get_time_ns(indio_dev));
194out:
195	mutex_unlock(&adc->lock);
196
197	iio_trigger_notify_done(indio_dev->trig);
198
199	return IRQ_HANDLED;
200}
201
202static void max1118_reg_disable(void *reg)
203{
204	regulator_disable(reg);
205}
206
207static int max1118_probe(struct spi_device *spi)
208{
209	struct iio_dev *indio_dev;
210	struct max1118 *adc;
211	const struct spi_device_id *id = spi_get_device_id(spi);
212	int ret;
213
214	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
215	if (!indio_dev)
216		return -ENOMEM;
217
218	adc = iio_priv(indio_dev);
219	adc->spi = spi;
220	mutex_init(&adc->lock);
221
222	if (id->driver_data == max1118) {
223		adc->reg = devm_regulator_get(&spi->dev, "vref");
224		if (IS_ERR(adc->reg))
225			return dev_err_probe(&spi->dev, PTR_ERR(adc->reg),
226					     "failed to get vref regulator\n");
227		ret = regulator_enable(adc->reg);
228		if (ret)
229			return ret;
230
231		ret = devm_add_action_or_reset(&spi->dev, max1118_reg_disable,
232					       adc->reg);
233		if (ret)
234			return ret;
235
236	}
237
238	indio_dev->name = spi_get_device_id(spi)->name;
239	indio_dev->info = &max1118_info;
240	indio_dev->modes = INDIO_DIRECT_MODE;
241	indio_dev->channels = max1118_channels;
242	indio_dev->num_channels = ARRAY_SIZE(max1118_channels);
243
244	/*
245	 * To reinitiate a conversion on CH0, it is necessary to allow for a
246	 * conversion to be complete and all of the data to be read out.  Once
247	 * a conversion has been completed, the MAX1117/MAX1118/MAX1119 will go
248	 * into AutoShutdown mode until the next conversion is initiated.
249	 */
250	max1118_read(indio_dev, 0);
251
252	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
253					      max1118_trigger_handler, NULL);
254	if (ret)
255		return ret;
256
257	return devm_iio_device_register(&spi->dev, indio_dev);
258}
259
260static const struct spi_device_id max1118_id[] = {
261	{ "max1117", max1117 },
262	{ "max1118", max1118 },
263	{ "max1119", max1119 },
264	{}
265};
266MODULE_DEVICE_TABLE(spi, max1118_id);
267
268static const struct of_device_id max1118_dt_ids[] = {
269	{ .compatible = "maxim,max1117" },
270	{ .compatible = "maxim,max1118" },
271	{ .compatible = "maxim,max1119" },
272	{},
273};
274MODULE_DEVICE_TABLE(of, max1118_dt_ids);
275
276static struct spi_driver max1118_spi_driver = {
277	.driver = {
278		.name = "max1118",
279		.of_match_table = max1118_dt_ids,
280	},
281	.probe = max1118_probe,
282	.id_table = max1118_id,
283};
284module_spi_driver(max1118_spi_driver);
285
286MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
287MODULE_DESCRIPTION("MAXIM MAX1117/MAX1118/MAX1119 ADCs driver");
288MODULE_LICENSE("GPL v2");
289