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 #define MCP4921_NUM_CHANNELS 1
21
22 enum mcp4922_supported_device_ids {
23 ID_MCP4902,
24 ID_MCP4912,
25 ID_MCP4921,
26 ID_MCP4922,
27 };
28
29 struct mcp4922_state {
30 struct spi_device *spi;
31 unsigned int value[MCP4922_NUM_CHANNELS];
32 unsigned int vref_mv;
33 struct regulator *vref_reg;
34 u8 mosi[2] __aligned(IIO_DMA_MINALIGN);
35 };
36
37 #define MCP4922_CHAN(chan, bits) { \
38 .type = IIO_VOLTAGE, \
39 .output = 1, \
40 .indexed = 1, \
41 .channel = chan, \
42 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
43 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
44 .scan_type = { \
45 .sign = 'u', \
46 .realbits = (bits), \
47 .storagebits = 16, \
48 .shift = 12 - (bits), \
49 }, \
50 }
51
mcp4922_spi_write(struct mcp4922_state * state,u8 addr,u32 val)52 static int mcp4922_spi_write(struct mcp4922_state *state, u8 addr, u32 val)
53 {
54 state->mosi[1] = val & 0xff;
55 state->mosi[0] = (addr == 0) ? 0x00 : 0x80;
56 state->mosi[0] |= 0x30 | ((val >> 8) & 0x0f);
57
58 return spi_write(state->spi, state->mosi, 2);
59 }
60
mcp4922_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)61 static int mcp4922_read_raw(struct iio_dev *indio_dev,
62 struct iio_chan_spec const *chan,
63 int *val,
64 int *val2,
65 long mask)
66 {
67 struct mcp4922_state *state = iio_priv(indio_dev);
68
69 switch (mask) {
70 case IIO_CHAN_INFO_RAW:
71 *val = state->value[chan->channel];
72 return IIO_VAL_INT;
73 case IIO_CHAN_INFO_SCALE:
74 *val = state->vref_mv;
75 *val2 = chan->scan_type.realbits;
76 return IIO_VAL_FRACTIONAL_LOG2;
77 default:
78 return -EINVAL;
79 }
80 }
81
mcp4922_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)82 static int mcp4922_write_raw(struct iio_dev *indio_dev,
83 struct iio_chan_spec const *chan,
84 int val,
85 int val2,
86 long mask)
87 {
88 struct mcp4922_state *state = iio_priv(indio_dev);
89 int ret;
90
91 if (val2 != 0)
92 return -EINVAL;
93
94 switch (mask) {
95 case IIO_CHAN_INFO_RAW:
96 if (val < 0 || val > GENMASK(chan->scan_type.realbits - 1, 0))
97 return -EINVAL;
98 val <<= chan->scan_type.shift;
99
100 ret = mcp4922_spi_write(state, chan->channel, val);
101 if (!ret)
102 state->value[chan->channel] = val;
103 return ret;
104
105 default:
106 return -EINVAL;
107 }
108 }
109
110 static const struct iio_chan_spec mcp4922_channels[4][MCP4922_NUM_CHANNELS] = {
111 [ID_MCP4902] = { MCP4922_CHAN(0, 8), MCP4922_CHAN(1, 8) },
112 [ID_MCP4912] = { MCP4922_CHAN(0, 10), MCP4922_CHAN(1, 10) },
113 [ID_MCP4921] = { MCP4922_CHAN(0, 12), {} },
114 [ID_MCP4922] = { MCP4922_CHAN(0, 12), MCP4922_CHAN(1, 12) },
115 };
116
117 static const struct iio_info mcp4922_info = {
118 .read_raw = &mcp4922_read_raw,
119 .write_raw = &mcp4922_write_raw,
120 };
121
mcp4922_probe(struct spi_device * spi)122 static int mcp4922_probe(struct spi_device *spi)
123 {
124 struct iio_dev *indio_dev;
125 struct mcp4922_state *state;
126 const struct spi_device_id *id;
127 int ret;
128
129 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
130 if (indio_dev == NULL)
131 return -ENOMEM;
132
133 state = iio_priv(indio_dev);
134 state->spi = spi;
135 state->vref_reg = devm_regulator_get(&spi->dev, "vref");
136 if (IS_ERR(state->vref_reg))
137 return dev_err_probe(&spi->dev, PTR_ERR(state->vref_reg),
138 "Vref regulator not specified\n");
139
140 ret = regulator_enable(state->vref_reg);
141 if (ret) {
142 dev_err(&spi->dev, "Failed to enable vref regulator: %d\n",
143 ret);
144 return ret;
145 }
146
147 ret = regulator_get_voltage(state->vref_reg);
148 if (ret < 0) {
149 dev_err(&spi->dev, "Failed to read vref regulator: %d\n",
150 ret);
151 goto error_disable_reg;
152 }
153 state->vref_mv = ret / 1000;
154
155 spi_set_drvdata(spi, indio_dev);
156 id = spi_get_device_id(spi);
157 indio_dev->info = &mcp4922_info;
158 indio_dev->modes = INDIO_DIRECT_MODE;
159 indio_dev->channels = mcp4922_channels[id->driver_data];
160 if (id->driver_data == ID_MCP4921)
161 indio_dev->num_channels = MCP4921_NUM_CHANNELS;
162 else
163 indio_dev->num_channels = MCP4922_NUM_CHANNELS;
164 indio_dev->name = id->name;
165
166 ret = iio_device_register(indio_dev);
167 if (ret) {
168 dev_err(&spi->dev, "Failed to register iio device: %d\n",
169 ret);
170 goto error_disable_reg;
171 }
172
173 return 0;
174
175 error_disable_reg:
176 regulator_disable(state->vref_reg);
177
178 return ret;
179 }
180
mcp4922_remove(struct spi_device * spi)181 static void mcp4922_remove(struct spi_device *spi)
182 {
183 struct iio_dev *indio_dev = spi_get_drvdata(spi);
184 struct mcp4922_state *state;
185
186 iio_device_unregister(indio_dev);
187 state = iio_priv(indio_dev);
188 regulator_disable(state->vref_reg);
189 }
190
191 static const struct spi_device_id mcp4922_id[] = {
192 {"mcp4902", ID_MCP4902},
193 {"mcp4912", ID_MCP4912},
194 {"mcp4921", ID_MCP4921},
195 {"mcp4922", ID_MCP4922},
196 {}
197 };
198 MODULE_DEVICE_TABLE(spi, mcp4922_id);
199
200 static struct spi_driver mcp4922_driver = {
201 .driver = {
202 .name = "mcp4922",
203 },
204 .probe = mcp4922_probe,
205 .remove = mcp4922_remove,
206 .id_table = mcp4922_id,
207 };
208 module_spi_driver(mcp4922_driver);
209
210 MODULE_AUTHOR("Michael Welling <mwelling@ieee.org>");
211 MODULE_DESCRIPTION("Microchip MCP4902, MCP4912, MCP4922 DAC");
212 MODULE_LICENSE("GPL v2");
213