1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * IIO DAC driver for Analog Devices AD8801 DAC
4 *
5 * Copyright (C) 2016 Gwenhael Goavec-Merou
6 */
7
8 #include <linux/iio/iio.h>
9 #include <linux/module.h>
10 #include <linux/regulator/consumer.h>
11 #include <linux/spi/spi.h>
12 #include <linux/sysfs.h>
13
14 #define AD8801_CFG_ADDR_OFFSET 8
15
16 enum ad8801_device_ids {
17 ID_AD8801,
18 ID_AD8803,
19 };
20
21 struct ad8801_state {
22 struct spi_device *spi;
23 unsigned char dac_cache[8]; /* Value write on each channel */
24 unsigned int vrefh_mv;
25 unsigned int vrefl_mv;
26
27 __be16 data __aligned(IIO_DMA_MINALIGN);
28 };
29
ad8801_spi_write(struct ad8801_state * state,u8 channel,unsigned char value)30 static int ad8801_spi_write(struct ad8801_state *state,
31 u8 channel, unsigned char value)
32 {
33 state->data = cpu_to_be16((channel << AD8801_CFG_ADDR_OFFSET) | value);
34 return spi_write(state->spi, &state->data, sizeof(state->data));
35 }
36
ad8801_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)37 static int ad8801_write_raw(struct iio_dev *indio_dev,
38 struct iio_chan_spec const *chan, int val, int val2, long mask)
39 {
40 struct ad8801_state *state = iio_priv(indio_dev);
41 int ret;
42
43 switch (mask) {
44 case IIO_CHAN_INFO_RAW:
45 if (val >= 256 || val < 0)
46 return -EINVAL;
47
48 ret = ad8801_spi_write(state, chan->channel, val);
49 if (ret == 0)
50 state->dac_cache[chan->channel] = val;
51 break;
52 default:
53 ret = -EINVAL;
54 }
55
56 return ret;
57 }
58
ad8801_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long info)59 static int ad8801_read_raw(struct iio_dev *indio_dev,
60 struct iio_chan_spec const *chan, int *val, int *val2, long info)
61 {
62 struct ad8801_state *state = iio_priv(indio_dev);
63
64 switch (info) {
65 case IIO_CHAN_INFO_RAW:
66 *val = state->dac_cache[chan->channel];
67 return IIO_VAL_INT;
68 case IIO_CHAN_INFO_SCALE:
69 *val = state->vrefh_mv - state->vrefl_mv;
70 *val2 = 8;
71 return IIO_VAL_FRACTIONAL_LOG2;
72 case IIO_CHAN_INFO_OFFSET:
73 *val = state->vrefl_mv;
74 return IIO_VAL_INT;
75 default:
76 return -EINVAL;
77 }
78
79 return -EINVAL;
80 }
81
82 static const struct iio_info ad8801_info = {
83 .read_raw = ad8801_read_raw,
84 .write_raw = ad8801_write_raw,
85 };
86
87 #define AD8801_CHANNEL(chan) { \
88 .type = IIO_VOLTAGE, \
89 .indexed = 1, \
90 .output = 1, \
91 .channel = chan, \
92 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
93 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
94 BIT(IIO_CHAN_INFO_OFFSET), \
95 }
96
97 static const struct iio_chan_spec ad8801_channels[] = {
98 AD8801_CHANNEL(0),
99 AD8801_CHANNEL(1),
100 AD8801_CHANNEL(2),
101 AD8801_CHANNEL(3),
102 AD8801_CHANNEL(4),
103 AD8801_CHANNEL(5),
104 AD8801_CHANNEL(6),
105 AD8801_CHANNEL(7),
106 };
107
ad8801_probe(struct spi_device * spi)108 static int ad8801_probe(struct spi_device *spi)
109 {
110 struct iio_dev *indio_dev;
111 struct ad8801_state *state;
112 const struct spi_device_id *id;
113 int ret;
114
115 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
116 if (indio_dev == NULL)
117 return -ENOMEM;
118
119 state = iio_priv(indio_dev);
120 state->spi = spi;
121 id = spi_get_device_id(spi);
122
123 ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vrefh");
124 if (ret < 0)
125 return dev_err_probe(&spi->dev, ret,
126 "failed to get Vrefh voltage\n");
127
128 state->vrefh_mv = ret / 1000;
129
130 if (id->driver_data == ID_AD8803) {
131 ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vrefl");
132 if (ret < 0)
133 return dev_err_probe(&spi->dev, ret,
134 "failed to get Vrefl voltage\n");
135
136 state->vrefl_mv = ret / 1000;
137 }
138
139 indio_dev->info = &ad8801_info;
140 indio_dev->modes = INDIO_DIRECT_MODE;
141 indio_dev->channels = ad8801_channels;
142 indio_dev->num_channels = ARRAY_SIZE(ad8801_channels);
143 indio_dev->name = id->name;
144
145 ret = devm_iio_device_register(&spi->dev, indio_dev);
146 if (ret)
147 return dev_err_probe(&spi->dev, ret,
148 "Failed to register iio device\n");
149
150 return 0;
151 }
152
153 static const struct spi_device_id ad8801_ids[] = {
154 {"ad8801", ID_AD8801},
155 {"ad8803", ID_AD8803},
156 {}
157 };
158 MODULE_DEVICE_TABLE(spi, ad8801_ids);
159
160 static struct spi_driver ad8801_driver = {
161 .driver = {
162 .name = "ad8801",
163 },
164 .probe = ad8801_probe,
165 .id_table = ad8801_ids,
166 };
167 module_spi_driver(ad8801_driver);
168
169 MODULE_AUTHOR("Gwenhael Goavec-Merou <[email protected]>");
170 MODULE_DESCRIPTION("Analog Devices AD8801/AD8803 DAC");
171 MODULE_LICENSE("GPL v2");
172