xref: /openbmc/linux/drivers/iio/dac/mcp4922.c (revision b593bce5)
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 
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 
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 
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 
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 
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