1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * ADS8344 16-bit 8-Channel ADC driver
4 *
5 * Author: Gregory CLEMENT <gregory.clement@bootlin.com>
6 *
7 * Datasheet: https://www.ti.com/lit/ds/symlink/ads8344.pdf
8 */
9
10#include <linux/delay.h>
11#include <linux/iio/buffer.h>
12#include <linux/iio/iio.h>
13#include <linux/module.h>
14#include <linux/regulator/consumer.h>
15#include <linux/spi/spi.h>
16
17#define ADS8344_START BIT(7)
18#define ADS8344_SINGLE_END BIT(2)
19#define ADS8344_CHANNEL(channel) ((channel) << 4)
20#define ADS8344_CLOCK_INTERNAL 0x2 /* PD1 = 1 and PD0 = 0 */
21
22struct ads8344 {
23	struct spi_device *spi;
24	struct regulator *reg;
25	/*
26	 * Lock protecting access to adc->tx_buff and rx_buff,
27	 * especially from concurrent read on sysfs file.
28	 */
29	struct mutex lock;
30
31	u8 tx_buf __aligned(IIO_DMA_MINALIGN);
32	u8 rx_buf[3];
33};
34
35#define ADS8344_VOLTAGE_CHANNEL(chan, addr)				\
36	{								\
37		.type = IIO_VOLTAGE,					\
38		.indexed = 1,						\
39		.channel = chan,					\
40		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
41		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
42		.address = addr,					\
43	}
44
45#define ADS8344_VOLTAGE_CHANNEL_DIFF(chan1, chan2, addr)		\
46	{								\
47		.type = IIO_VOLTAGE,					\
48		.indexed = 1,						\
49		.channel = (chan1),					\
50		.channel2 = (chan2),					\
51		.differential = 1,					\
52		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
53		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
54		.address = addr,					\
55	}
56
57static const struct iio_chan_spec ads8344_channels[] = {
58	ADS8344_VOLTAGE_CHANNEL(0, 0),
59	ADS8344_VOLTAGE_CHANNEL(1, 4),
60	ADS8344_VOLTAGE_CHANNEL(2, 1),
61	ADS8344_VOLTAGE_CHANNEL(3, 5),
62	ADS8344_VOLTAGE_CHANNEL(4, 2),
63	ADS8344_VOLTAGE_CHANNEL(5, 6),
64	ADS8344_VOLTAGE_CHANNEL(6, 3),
65	ADS8344_VOLTAGE_CHANNEL(7, 7),
66	ADS8344_VOLTAGE_CHANNEL_DIFF(0, 1, 8),
67	ADS8344_VOLTAGE_CHANNEL_DIFF(2, 3, 9),
68	ADS8344_VOLTAGE_CHANNEL_DIFF(4, 5, 10),
69	ADS8344_VOLTAGE_CHANNEL_DIFF(6, 7, 11),
70	ADS8344_VOLTAGE_CHANNEL_DIFF(1, 0, 12),
71	ADS8344_VOLTAGE_CHANNEL_DIFF(3, 2, 13),
72	ADS8344_VOLTAGE_CHANNEL_DIFF(5, 4, 14),
73	ADS8344_VOLTAGE_CHANNEL_DIFF(7, 6, 15),
74};
75
76static int ads8344_adc_conversion(struct ads8344 *adc, int channel,
77				  bool differential)
78{
79	struct spi_device *spi = adc->spi;
80	int ret;
81
82	adc->tx_buf = ADS8344_START;
83	if (!differential)
84		adc->tx_buf |= ADS8344_SINGLE_END;
85	adc->tx_buf |= ADS8344_CHANNEL(channel);
86	adc->tx_buf |= ADS8344_CLOCK_INTERNAL;
87
88	ret = spi_write(spi, &adc->tx_buf, 1);
89	if (ret)
90		return ret;
91
92	udelay(9);
93
94	ret = spi_read(spi, adc->rx_buf, sizeof(adc->rx_buf));
95	if (ret)
96		return ret;
97
98	return adc->rx_buf[0] << 9 | adc->rx_buf[1] << 1 | adc->rx_buf[2] >> 7;
99}
100
101static int ads8344_read_raw(struct iio_dev *iio,
102			    struct iio_chan_spec const *channel, int *value,
103			    int *shift, long mask)
104{
105	struct ads8344 *adc = iio_priv(iio);
106
107	switch (mask) {
108	case IIO_CHAN_INFO_RAW:
109		mutex_lock(&adc->lock);
110		*value = ads8344_adc_conversion(adc, channel->address,
111						channel->differential);
112		mutex_unlock(&adc->lock);
113		if (*value < 0)
114			return *value;
115
116		return IIO_VAL_INT;
117	case IIO_CHAN_INFO_SCALE:
118		*value = regulator_get_voltage(adc->reg);
119		if (*value < 0)
120			return *value;
121
122		/* convert regulator output voltage to mV */
123		*value /= 1000;
124		*shift = 16;
125
126		return IIO_VAL_FRACTIONAL_LOG2;
127	default:
128		return -EINVAL;
129	}
130}
131
132static const struct iio_info ads8344_info = {
133	.read_raw = ads8344_read_raw,
134};
135
136static void ads8344_reg_disable(void *data)
137{
138	regulator_disable(data);
139}
140
141static int ads8344_probe(struct spi_device *spi)
142{
143	struct iio_dev *indio_dev;
144	struct ads8344 *adc;
145	int ret;
146
147	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
148	if (!indio_dev)
149		return -ENOMEM;
150
151	adc = iio_priv(indio_dev);
152	adc->spi = spi;
153	mutex_init(&adc->lock);
154
155	indio_dev->name = dev_name(&spi->dev);
156	indio_dev->info = &ads8344_info;
157	indio_dev->modes = INDIO_DIRECT_MODE;
158	indio_dev->channels = ads8344_channels;
159	indio_dev->num_channels = ARRAY_SIZE(ads8344_channels);
160
161	adc->reg = devm_regulator_get(&spi->dev, "vref");
162	if (IS_ERR(adc->reg))
163		return PTR_ERR(adc->reg);
164
165	ret = regulator_enable(adc->reg);
166	if (ret)
167		return ret;
168
169	ret = devm_add_action_or_reset(&spi->dev, ads8344_reg_disable, adc->reg);
170	if (ret)
171		return ret;
172
173	return devm_iio_device_register(&spi->dev, indio_dev);
174}
175
176static const struct of_device_id ads8344_of_match[] = {
177	{ .compatible = "ti,ads8344", },
178	{}
179};
180MODULE_DEVICE_TABLE(of, ads8344_of_match);
181
182static struct spi_driver ads8344_driver = {
183	.driver = {
184		.name = "ads8344",
185		.of_match_table = ads8344_of_match,
186	},
187	.probe = ads8344_probe,
188};
189module_spi_driver(ads8344_driver);
190
191MODULE_AUTHOR("Gregory CLEMENT <gregory.clement@bootlin.com>");
192MODULE_DESCRIPTION("ADS8344 driver");
193MODULE_LICENSE("GPL");
194