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, buf: &adc->tx_buf, len: 1);
89 if (ret)
90 return ret;
91
92 udelay(usec: 9);
93
94 ret = spi_read(spi, buf: adc->rx_buf, len: 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(indio_dev: iio);
106
107 switch (mask) {
108 case IIO_CHAN_INFO_RAW:
109 mutex_lock(&adc->lock);
110 *value = ads8344_adc_conversion(adc, channel: channel->address,
111 differential: channel->differential);
112 mutex_unlock(lock: &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(regulator: 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(regulator: 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(parent: &spi->dev, sizeof_priv: 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(dev: &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(dev: &spi->dev, id: "vref");
162 if (IS_ERR(ptr: adc->reg))
163 return PTR_ERR(ptr: adc->reg);
164
165 ret = regulator_enable(regulator: 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

Provided by KDAB

Privacy Policy
Improve your Profiling and Debugging skills
Find out more

source code of linux/drivers/iio/adc/ti-ads8344.c