1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * mcp4922.c
4 *
5 * Driver for Microchip Digital to Analog Converters.
6 * Supports MCP4902, MCP4912, and MCP4922.
7 *
8 * Copyright (c) 2014 EMAC Inc.
9 */
10
11 #include <linux/module.h>
12 #include <linux/init.h>
13 #include <linux/spi/spi.h>
14 #include <linux/iio/iio.h>
15 #include <linux/iio/sysfs.h>
16 #include <linux/regulator/consumer.h>
17 #include <linux/bitops.h>
18
19 #define MCP4922_NUM_CHANNELS 2
20
21 enum mcp4922_supported_device_ids {
22 ID_MCP4902,
23 ID_MCP4912,
24 ID_MCP4922,
25 };
26
27 struct mcp4922_state {
28 struct spi_device *spi;
29 unsigned int value[MCP4922_NUM_CHANNELS];
30 unsigned int vref_mv;
31 struct regulator *vref_reg;
32 u8 mosi[2] ____cacheline_aligned;
33 };
34
35 #define MCP4922_CHAN(chan, bits) { \
36 .type = IIO_VOLTAGE, \
37 .output = 1, \
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 .scan_type = { \
43 .sign = 'u', \
44 .realbits = (bits), \
45 .storagebits = 16, \
46 .shift = 12 - (bits), \
47 }, \
48 }
49
mcp4922_spi_write(struct mcp4922_state * state,u8 addr,u32 val)50 static int mcp4922_spi_write(struct mcp4922_state *state, u8 addr, u32 val)
51 {
52 state->mosi[1] = val & 0xff;
53 state->mosi[0] = (addr == 0) ? 0x00 : 0x80;
54 state->mosi[0] |= 0x30 | ((val >> 8) & 0x0f);
55
56 return spi_write(state->spi, state->mosi, 2);
57 }
58
mcp4922_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)59 static int mcp4922_read_raw(struct iio_dev *indio_dev,
60 struct iio_chan_spec const *chan,
61 int *val,
62 int *val2,
63 long mask)
64 {
65 struct mcp4922_state *state = iio_priv(indio_dev);
66
67 switch (mask) {
68 case IIO_CHAN_INFO_RAW:
69 *val = state->value[chan->channel];
70 return IIO_VAL_INT;
71 case IIO_CHAN_INFO_SCALE:
72 *val = state->vref_mv;
73 *val2 = chan->scan_type.realbits;
74 return IIO_VAL_FRACTIONAL_LOG2;
75 default:
76 return -EINVAL;
77 }
78 }
79
mcp4922_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)80 static int mcp4922_write_raw(struct iio_dev *indio_dev,
81 struct iio_chan_spec const *chan,
82 int val,
83 int val2,
84 long mask)
85 {
86 struct mcp4922_state *state = iio_priv(indio_dev);
87 int ret;
88
89 if (val2 != 0)
90 return -EINVAL;
91
92 switch (mask) {
93 case IIO_CHAN_INFO_RAW:
94 if (val < 0 || val > GENMASK(chan->scan_type.realbits - 1, 0))
95 return -EINVAL;
96 val <<= chan->scan_type.shift;
97
98 ret = mcp4922_spi_write(state, chan->channel, val);
99 if (!ret)
100 state->value[chan->channel] = val;
101 return ret;
102
103 default:
104 return -EINVAL;
105 }
106 }
107
108 static const struct iio_chan_spec mcp4922_channels[3][MCP4922_NUM_CHANNELS] = {
109 [ID_MCP4902] = { MCP4922_CHAN(0, 8), MCP4922_CHAN(1, 8) },
110 [ID_MCP4912] = { MCP4922_CHAN(0, 10), MCP4922_CHAN(1, 10) },
111 [ID_MCP4922] = { MCP4922_CHAN(0, 12), MCP4922_CHAN(1, 12) },
112 };
113
114 static const struct iio_info mcp4922_info = {
115 .read_raw = &mcp4922_read_raw,
116 .write_raw = &mcp4922_write_raw,
117 };
118
mcp4922_probe(struct spi_device * spi)119 static int mcp4922_probe(struct spi_device *spi)
120 {
121 struct iio_dev *indio_dev;
122 struct mcp4922_state *state;
123 const struct spi_device_id *id;
124 int ret;
125
126 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
127 if (indio_dev == NULL)
128 return -ENOMEM;
129
130 state = iio_priv(indio_dev);
131 state->spi = spi;
132 state->vref_reg = devm_regulator_get(&spi->dev, "vref");
133 if (IS_ERR(state->vref_reg)) {
134 dev_err(&spi->dev, "Vref regulator not specified\n");
135 return PTR_ERR(state->vref_reg);
136 }
137
138 ret = regulator_enable(state->vref_reg);
139 if (ret) {
140 dev_err(&spi->dev, "Failed to enable vref regulator: %d\n",
141 ret);
142 return ret;
143 }
144
145 ret = regulator_get_voltage(state->vref_reg);
146 if (ret < 0) {
147 dev_err(&spi->dev, "Failed to read vref regulator: %d\n",
148 ret);
149 goto error_disable_reg;
150 }
151 state->vref_mv = ret / 1000;
152
153 spi_set_drvdata(spi, indio_dev);
154 id = spi_get_device_id(spi);
155 indio_dev->dev.parent = &spi->dev;
156 indio_dev->info = &mcp4922_info;
157 indio_dev->modes = INDIO_DIRECT_MODE;
158 indio_dev->channels = mcp4922_channels[id->driver_data];
159 indio_dev->num_channels = MCP4922_NUM_CHANNELS;
160 indio_dev->name = id->name;
161
162 ret = iio_device_register(indio_dev);
163 if (ret) {
164 dev_err(&spi->dev, "Failed to register iio device: %d\n",
165 ret);
166 goto error_disable_reg;
167 }
168
169 return 0;
170
171 error_disable_reg:
172 regulator_disable(state->vref_reg);
173
174 return ret;
175 }
176
mcp4922_remove(struct spi_device * spi)177 static int mcp4922_remove(struct spi_device *spi)
178 {
179 struct iio_dev *indio_dev = spi_get_drvdata(spi);
180 struct mcp4922_state *state;
181
182 iio_device_unregister(indio_dev);
183 state = iio_priv(indio_dev);
184 regulator_disable(state->vref_reg);
185
186 return 0;
187 }
188
189 static const struct spi_device_id mcp4922_id[] = {
190 {"mcp4902", ID_MCP4902},
191 {"mcp4912", ID_MCP4912},
192 {"mcp4922", ID_MCP4922},
193 {}
194 };
195 MODULE_DEVICE_TABLE(spi, mcp4922_id);
196
197 static struct spi_driver mcp4922_driver = {
198 .driver = {
199 .name = "mcp4922",
200 },
201 .probe = mcp4922_probe,
202 .remove = mcp4922_remove,
203 .id_table = mcp4922_id,
204 };
205 module_spi_driver(mcp4922_driver);
206
207 MODULE_AUTHOR("Michael Welling <mwelling@ieee.org>");
208 MODULE_DESCRIPTION("Microchip MCP4902, MCP4912, MCP4922 DAC");
209 MODULE_LICENSE("GPL v2");
210
