1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2023 Anshul Dalal <anshulusr@gmail.com>
4 *
5 * Driver for Microchip MCP4801, MCP4802, MCP4811, MCP4812, MCP4821 and MCP4822
6 *
7 * Based on the work of:
8 * Michael Welling (MCP4922 Driver)
9 *
10 * Datasheet:
11 * MCP48x1: https://ww1.microchip.com/downloads/en/DeviceDoc/22244B.pdf
12 * MCP48x2: https://ww1.microchip.com/downloads/en/DeviceDoc/20002249B.pdf
13 *
14 * TODO:
15 * - Configurable gain
16 * - Regulator control
17 */
18
19#include <linux/module.h>
20#include <linux/mod_devicetable.h>
21#include <linux/spi/spi.h>
22
23#include <linux/iio/iio.h>
24#include <linux/iio/types.h>
25
26#include <asm/unaligned.h>
27
28#define MCP4821_ACTIVE_MODE BIT(12)
29#define MCP4802_SECOND_CHAN BIT(15)
30
31/* DAC uses an internal Voltage reference of 4.096V at a gain of 2x */
32#define MCP4821_2X_GAIN_VREF_MV 4096
33
34enum mcp4821_supported_drvice_ids {
35 ID_MCP4801,
36 ID_MCP4802,
37 ID_MCP4811,
38 ID_MCP4812,
39 ID_MCP4821,
40 ID_MCP4822,
41};
42
43struct mcp4821_state {
44 struct spi_device *spi;
45 u16 dac_value[2];
46};
47
48struct mcp4821_chip_info {
49 const char *name;
50 int num_channels;
51 const struct iio_chan_spec channels[2];
52};
53
54#define MCP4821_CHAN(channel_id, resolution) \
55 { \
56 .type = IIO_VOLTAGE, .output = 1, .indexed = 1, \
57 .channel = (channel_id), \
58 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
59 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
60 .scan_type = { \
61 .realbits = (resolution), \
62 .shift = 12 - (resolution), \
63 }, \
64 }
65
66static const struct mcp4821_chip_info mcp4821_chip_info_table[6] = {
67 [ID_MCP4801] = {
68 .name = "mcp4801",
69 .num_channels = 1,
70 .channels = {
71 MCP4821_CHAN(0, 8),
72 },
73 },
74 [ID_MCP4802] = {
75 .name = "mcp4802",
76 .num_channels = 2,
77 .channels = {
78 MCP4821_CHAN(0, 8),
79 MCP4821_CHAN(1, 8),
80 },
81 },
82 [ID_MCP4811] = {
83 .name = "mcp4811",
84 .num_channels = 1,
85 .channels = {
86 MCP4821_CHAN(0, 10),
87 },
88 },
89 [ID_MCP4812] = {
90 .name = "mcp4812",
91 .num_channels = 2,
92 .channels = {
93 MCP4821_CHAN(0, 10),
94 MCP4821_CHAN(1, 10),
95 },
96 },
97 [ID_MCP4821] = {
98 .name = "mcp4821",
99 .num_channels = 1,
100 .channels = {
101 MCP4821_CHAN(0, 12),
102 },
103 },
104 [ID_MCP4822] = {
105 .name = "mcp4822",
106 .num_channels = 2,
107 .channels = {
108 MCP4821_CHAN(0, 12),
109 MCP4821_CHAN(1, 12),
110 },
111 },
112};
113
114static int mcp4821_read_raw(struct iio_dev *indio_dev,
115 struct iio_chan_spec const *chan, int *val,
116 int *val2, long mask)
117{
118 struct mcp4821_state *state;
119
120 switch (mask) {
121 case IIO_CHAN_INFO_RAW:
122 state = iio_priv(indio_dev);
123 *val = state->dac_value[chan->channel];
124 return IIO_VAL_INT;
125 case IIO_CHAN_INFO_SCALE:
126 *val = MCP4821_2X_GAIN_VREF_MV;
127 *val2 = chan->scan_type.realbits;
128 return IIO_VAL_FRACTIONAL_LOG2;
129 default:
130 return -EINVAL;
131 }
132}
133
134static int mcp4821_write_raw(struct iio_dev *indio_dev,
135 struct iio_chan_spec const *chan, int val,
136 int val2, long mask)
137{
138 struct mcp4821_state *state = iio_priv(indio_dev);
139 u16 write_val;
140 __be16 write_buffer;
141 int ret;
142
143 if (val2 != 0)
144 return -EINVAL;
145
146 if (val < 0 || val >= BIT(chan->scan_type.realbits))
147 return -EINVAL;
148
149 if (mask != IIO_CHAN_INFO_RAW)
150 return -EINVAL;
151
152 write_val = MCP4821_ACTIVE_MODE | val << chan->scan_type.shift;
153 if (chan->channel)
154 write_val |= MCP4802_SECOND_CHAN;
155
156 write_buffer = cpu_to_be16(write_val);
157 ret = spi_write(spi: state->spi, buf: &write_buffer, len: sizeof(write_buffer));
158 if (ret) {
159 dev_err(&state->spi->dev, "Failed to write to device: %d", ret);
160 return ret;
161 }
162
163 state->dac_value[chan->channel] = val;
164
165 return 0;
166}
167
168static const struct iio_info mcp4821_info = {
169 .read_raw = &mcp4821_read_raw,
170 .write_raw = &mcp4821_write_raw,
171};
172
173static int mcp4821_probe(struct spi_device *spi)
174{
175 struct iio_dev *indio_dev;
176 struct mcp4821_state *state;
177 const struct mcp4821_chip_info *info;
178
179 indio_dev = devm_iio_device_alloc(parent: &spi->dev, sizeof_priv: sizeof(*state));
180 if (indio_dev == NULL)
181 return -ENOMEM;
182
183 state = iio_priv(indio_dev);
184 state->spi = spi;
185
186 info = spi_get_device_match_data(sdev: spi);
187 indio_dev->name = info->name;
188 indio_dev->info = &mcp4821_info;
189 indio_dev->modes = INDIO_DIRECT_MODE;
190 indio_dev->channels = info->channels;
191 indio_dev->num_channels = info->num_channels;
192
193 return devm_iio_device_register(&spi->dev, indio_dev);
194}
195
196#define MCP4821_COMPATIBLE(of_compatible, id) \
197 { \
198 .compatible = of_compatible, \
199 .data = &mcp4821_chip_info_table[id] \
200 }
201
202static const struct of_device_id mcp4821_of_table[] = {
203 MCP4821_COMPATIBLE("microchip,mcp4801", ID_MCP4801),
204 MCP4821_COMPATIBLE("microchip,mcp4802", ID_MCP4802),
205 MCP4821_COMPATIBLE("microchip,mcp4811", ID_MCP4811),
206 MCP4821_COMPATIBLE("microchip,mcp4812", ID_MCP4812),
207 MCP4821_COMPATIBLE("microchip,mcp4821", ID_MCP4821),
208 MCP4821_COMPATIBLE("microchip,mcp4822", ID_MCP4822),
209 { /* Sentinel */ }
210};
211MODULE_DEVICE_TABLE(of, mcp4821_of_table);
212
213static const struct spi_device_id mcp4821_id_table[] = {
214 { "mcp4801", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4801]},
215 { "mcp4802", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4802]},
216 { "mcp4811", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4811]},
217 { "mcp4812", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4812]},
218 { "mcp4821", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4821]},
219 { "mcp4822", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4822]},
220 { /* Sentinel */ }
221};
222MODULE_DEVICE_TABLE(spi, mcp4821_id_table);
223
224static struct spi_driver mcp4821_driver = {
225 .driver = {
226 .name = "mcp4821",
227 .of_match_table = mcp4821_of_table,
228 },
229 .probe = mcp4821_probe,
230 .id_table = mcp4821_id_table,
231};
232module_spi_driver(mcp4821_driver);
233
234MODULE_AUTHOR("Anshul Dalal <anshulusr@gmail.com>");
235MODULE_DESCRIPTION("Microchip MCP4821 DAC Driver");
236MODULE_LICENSE("GPL");
237

source code of linux/drivers/iio/dac/mcp4821.c