1 // SPDX-License-Identifier: GPL-2.0
3 * Driver for Microchip MCP3911, Two-channel Analog Front End
5 * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com>
6 * Copyright (C) 2018 Kent Gustavsson <kent@minoris.se>
9 #include <linux/delay.h>
10 #include <linux/err.h>
11 #include <linux/iio/iio.h>
12 #include <linux/module.h>
13 #include <linux/regulator/consumer.h>
14 #include <linux/spi/spi.h>
16 #define MCP3911_REG_CHANNEL0 0x00
17 #define MCP3911_REG_CHANNEL1 0x03
18 #define MCP3911_REG_MOD 0x06
19 #define MCP3911_REG_PHASE 0x07
20 #define MCP3911_REG_GAIN 0x09
22 #define MCP3911_REG_STATUSCOM 0x0a
23 #define MCP3911_STATUSCOM_CH1_24WIDTH BIT(4)
24 #define MCP3911_STATUSCOM_CH0_24WIDTH BIT(3)
25 #define MCP3911_STATUSCOM_EN_OFFCAL BIT(2)
26 #define MCP3911_STATUSCOM_EN_GAINCAL BIT(1)
28 #define MCP3911_REG_CONFIG 0x0c
29 #define MCP3911_CONFIG_CLKEXT BIT(1)
30 #define MCP3911_CONFIG_VREFEXT BIT(2)
32 #define MCP3911_REG_OFFCAL_CH0 0x0e
33 #define MCP3911_REG_GAINCAL_CH0 0x11
34 #define MCP3911_REG_OFFCAL_CH1 0x14
35 #define MCP3911_REG_GAINCAL_CH1 0x17
36 #define MCP3911_REG_VREFCAL 0x1a
38 #define MCP3911_CHANNEL(x) (MCP3911_REG_CHANNEL0 + x * 3)
39 #define MCP3911_OFFCAL(x) (MCP3911_REG_OFFCAL_CH0 + x * 6)
41 /* Internal voltage reference in uV */
42 #define MCP3911_INT_VREF_UV 1200000
44 #define MCP3911_REG_READ(reg, id) ((((reg) << 1) | ((id) << 5) | (1 << 0)) & 0xff)
45 #define MCP3911_REG_WRITE(reg, id) ((((reg) << 1) | ((id) << 5) | (0 << 0)) & 0xff)
47 #define MCP3911_NUM_CHANNELS 2
50 struct spi_device *spi;
52 struct regulator *vref;
57 static int mcp3911_read(struct mcp3911 *adc, u8 reg, u32 *val, u8 len)
61 reg = MCP3911_REG_READ(reg, adc->dev_addr);
62 ret = spi_write_then_read(adc->spi, ®, 1, val, len);
67 *val >>= ((4 - len) * 8);
68 dev_dbg(&adc->spi->dev, "reading 0x%x from register 0x%x\n", *val,
73 static int mcp3911_write(struct mcp3911 *adc, u8 reg, u32 val, u8 len)
75 dev_dbg(&adc->spi->dev, "writing 0x%x to register 0x%x\n", val, reg);
77 val <<= (3 - len) * 8;
79 val |= MCP3911_REG_WRITE(reg, adc->dev_addr);
81 return spi_write(adc->spi, &val, len + 1);
84 static int mcp3911_update(struct mcp3911 *adc, u8 reg, u32 mask,
90 ret = mcp3911_read(adc, reg, &tmp, len);
96 return mcp3911_write(adc, reg, val, len);
99 static int mcp3911_read_raw(struct iio_dev *indio_dev,
100 struct iio_chan_spec const *channel, int *val,
101 int *val2, long mask)
103 struct mcp3911 *adc = iio_priv(indio_dev);
106 mutex_lock(&adc->lock);
108 case IIO_CHAN_INFO_RAW:
109 ret = mcp3911_read(adc,
110 MCP3911_CHANNEL(channel->channel), val, 3);
117 case IIO_CHAN_INFO_OFFSET:
118 ret = mcp3911_read(adc,
119 MCP3911_OFFCAL(channel->channel), val, 3);
126 case IIO_CHAN_INFO_SCALE:
128 ret = regulator_get_voltage(adc->vref);
130 dev_err(indio_dev->dev.parent,
131 "failed to get vref voltage: %d\n",
138 *val = MCP3911_INT_VREF_UV;
142 ret = IIO_VAL_FRACTIONAL_LOG2;
147 mutex_unlock(&adc->lock);
151 static int mcp3911_write_raw(struct iio_dev *indio_dev,
152 struct iio_chan_spec const *channel, int val,
155 struct mcp3911 *adc = iio_priv(indio_dev);
158 mutex_lock(&adc->lock);
160 case IIO_CHAN_INFO_OFFSET:
167 ret = mcp3911_write(adc, MCP3911_OFFCAL(channel->channel), val,
173 ret = mcp3911_update(adc, MCP3911_REG_STATUSCOM,
174 MCP3911_STATUSCOM_EN_OFFCAL,
175 MCP3911_STATUSCOM_EN_OFFCAL, 2);
180 mutex_unlock(&adc->lock);
184 #define MCP3911_CHAN(idx) { \
185 .type = IIO_VOLTAGE, \
188 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
189 BIT(IIO_CHAN_INFO_OFFSET) | \
190 BIT(IIO_CHAN_INFO_SCALE), \
193 static const struct iio_chan_spec mcp3911_channels[] = {
198 static const struct iio_info mcp3911_info = {
199 .read_raw = mcp3911_read_raw,
200 .write_raw = mcp3911_write_raw,
203 static int mcp3911_config(struct mcp3911 *adc, struct device_node *of_node)
208 of_property_read_u32(of_node, "device-addr", &adc->dev_addr);
209 if (adc->dev_addr > 3) {
210 dev_err(&adc->spi->dev,
211 "invalid device address (%i). Must be in range 0-3.\n",
215 dev_dbg(&adc->spi->dev, "use device address %i\n", adc->dev_addr);
217 ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &configreg, 2);
222 dev_dbg(&adc->spi->dev, "use external voltage reference\n");
223 configreg |= MCP3911_CONFIG_VREFEXT;
225 dev_dbg(&adc->spi->dev,
226 "use internal voltage reference (1.2V)\n");
227 configreg &= ~MCP3911_CONFIG_VREFEXT;
231 dev_dbg(&adc->spi->dev, "use external clock as clocksource\n");
232 configreg |= MCP3911_CONFIG_CLKEXT;
234 dev_dbg(&adc->spi->dev,
235 "use crystal oscillator as clocksource\n");
236 configreg &= ~MCP3911_CONFIG_CLKEXT;
239 return mcp3911_write(adc, MCP3911_REG_CONFIG, configreg, 2);
242 static int mcp3911_probe(struct spi_device *spi)
244 struct iio_dev *indio_dev;
248 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
252 adc = iio_priv(indio_dev);
255 adc->vref = devm_regulator_get_optional(&adc->spi->dev, "vref");
256 if (IS_ERR(adc->vref)) {
257 if (PTR_ERR(adc->vref) == -ENODEV) {
260 dev_err(&adc->spi->dev,
261 "failed to get regulator (%ld)\n",
263 return PTR_ERR(adc->vref);
267 ret = regulator_enable(adc->vref);
272 adc->clki = devm_clk_get(&adc->spi->dev, NULL);
273 if (IS_ERR(adc->clki)) {
274 if (PTR_ERR(adc->clki) == -ENOENT) {
277 dev_err(&adc->spi->dev,
278 "failed to get adc clk (%ld)\n",
280 ret = PTR_ERR(adc->clki);
284 ret = clk_prepare_enable(adc->clki);
286 dev_err(&adc->spi->dev,
287 "Failed to enable clki: %d\n", ret);
292 ret = mcp3911_config(adc, spi->dev.of_node);
296 indio_dev->name = spi_get_device_id(spi)->name;
297 indio_dev->modes = INDIO_DIRECT_MODE;
298 indio_dev->info = &mcp3911_info;
299 spi_set_drvdata(spi, indio_dev);
301 indio_dev->channels = mcp3911_channels;
302 indio_dev->num_channels = ARRAY_SIZE(mcp3911_channels);
304 mutex_init(&adc->lock);
306 ret = iio_device_register(indio_dev);
313 clk_disable_unprepare(adc->clki);
316 regulator_disable(adc->vref);
321 static int mcp3911_remove(struct spi_device *spi)
323 struct iio_dev *indio_dev = spi_get_drvdata(spi);
324 struct mcp3911 *adc = iio_priv(indio_dev);
326 iio_device_unregister(indio_dev);
328 clk_disable_unprepare(adc->clki);
330 regulator_disable(adc->vref);
335 static const struct of_device_id mcp3911_dt_ids[] = {
336 { .compatible = "microchip,mcp3911" },
339 MODULE_DEVICE_TABLE(of, mcp3911_dt_ids);
341 static const struct spi_device_id mcp3911_id[] = {
345 MODULE_DEVICE_TABLE(spi, mcp3911_id);
347 static struct spi_driver mcp3911_driver = {
350 .of_match_table = mcp3911_dt_ids,
352 .probe = mcp3911_probe,
353 .remove = mcp3911_remove,
354 .id_table = mcp3911_id,
356 module_spi_driver(mcp3911_driver);
358 MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson@gmail.com>");
359 MODULE_AUTHOR("Kent Gustavsson <kent@minoris.se>");
360 MODULE_DESCRIPTION("Microchip Technology MCP3911");
361 MODULE_LICENSE("GPL v2");