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 mV */
42 #define MCP3911_INT_VREF_MV 1200
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);
114 *val = sign_extend32(*val, 23);
119 case IIO_CHAN_INFO_OFFSET:
120 ret = mcp3911_read(adc,
121 MCP3911_OFFCAL(channel->channel), val, 3);
128 case IIO_CHAN_INFO_SCALE:
130 ret = regulator_get_voltage(adc->vref);
132 dev_err(indio_dev->dev.parent,
133 "failed to get vref voltage: %d\n",
140 *val = MCP3911_INT_VREF_MV;
144 * For 24bit Conversion
145 * Raw = ((Voltage)/(Vref) * 2^23 * Gain * 1.5
146 * Voltage = Raw * (Vref)/(2^23 * Gain * 1.5)
149 /* val2 = (2^23 * 1.5) */
151 ret = IIO_VAL_FRACTIONAL;
156 mutex_unlock(&adc->lock);
160 static int mcp3911_write_raw(struct iio_dev *indio_dev,
161 struct iio_chan_spec const *channel, int val,
164 struct mcp3911 *adc = iio_priv(indio_dev);
167 mutex_lock(&adc->lock);
169 case IIO_CHAN_INFO_OFFSET:
176 ret = mcp3911_write(adc, MCP3911_OFFCAL(channel->channel), val,
182 ret = mcp3911_update(adc, MCP3911_REG_STATUSCOM,
183 MCP3911_STATUSCOM_EN_OFFCAL,
184 MCP3911_STATUSCOM_EN_OFFCAL, 2);
189 mutex_unlock(&adc->lock);
193 #define MCP3911_CHAN(idx) { \
194 .type = IIO_VOLTAGE, \
197 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
198 BIT(IIO_CHAN_INFO_OFFSET) | \
199 BIT(IIO_CHAN_INFO_SCALE), \
202 static const struct iio_chan_spec mcp3911_channels[] = {
207 static const struct iio_info mcp3911_info = {
208 .read_raw = mcp3911_read_raw,
209 .write_raw = mcp3911_write_raw,
212 static int mcp3911_config(struct mcp3911 *adc, struct device_node *of_node)
217 of_property_read_u32(of_node, "device-addr", &adc->dev_addr);
218 if (adc->dev_addr > 3) {
219 dev_err(&adc->spi->dev,
220 "invalid device address (%i). Must be in range 0-3.\n",
224 dev_dbg(&adc->spi->dev, "use device address %i\n", adc->dev_addr);
226 ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &configreg, 2);
231 dev_dbg(&adc->spi->dev, "use external voltage reference\n");
232 configreg |= MCP3911_CONFIG_VREFEXT;
234 dev_dbg(&adc->spi->dev,
235 "use internal voltage reference (1.2V)\n");
236 configreg &= ~MCP3911_CONFIG_VREFEXT;
240 dev_dbg(&adc->spi->dev, "use external clock as clocksource\n");
241 configreg |= MCP3911_CONFIG_CLKEXT;
243 dev_dbg(&adc->spi->dev,
244 "use crystal oscillator as clocksource\n");
245 configreg &= ~MCP3911_CONFIG_CLKEXT;
248 return mcp3911_write(adc, MCP3911_REG_CONFIG, configreg, 2);
251 static int mcp3911_probe(struct spi_device *spi)
253 struct iio_dev *indio_dev;
257 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
261 adc = iio_priv(indio_dev);
264 adc->vref = devm_regulator_get_optional(&adc->spi->dev, "vref");
265 if (IS_ERR(adc->vref)) {
266 if (PTR_ERR(adc->vref) == -ENODEV) {
269 dev_err(&adc->spi->dev,
270 "failed to get regulator (%ld)\n",
272 return PTR_ERR(adc->vref);
276 ret = regulator_enable(adc->vref);
281 adc->clki = devm_clk_get(&adc->spi->dev, NULL);
282 if (IS_ERR(adc->clki)) {
283 if (PTR_ERR(adc->clki) == -ENOENT) {
286 dev_err(&adc->spi->dev,
287 "failed to get adc clk (%ld)\n",
289 ret = PTR_ERR(adc->clki);
293 ret = clk_prepare_enable(adc->clki);
295 dev_err(&adc->spi->dev,
296 "Failed to enable clki: %d\n", ret);
301 ret = mcp3911_config(adc, spi->dev.of_node);
305 indio_dev->name = spi_get_device_id(spi)->name;
306 indio_dev->modes = INDIO_DIRECT_MODE;
307 indio_dev->info = &mcp3911_info;
308 spi_set_drvdata(spi, indio_dev);
310 indio_dev->channels = mcp3911_channels;
311 indio_dev->num_channels = ARRAY_SIZE(mcp3911_channels);
313 mutex_init(&adc->lock);
315 ret = iio_device_register(indio_dev);
322 clk_disable_unprepare(adc->clki);
325 regulator_disable(adc->vref);
330 static int mcp3911_remove(struct spi_device *spi)
332 struct iio_dev *indio_dev = spi_get_drvdata(spi);
333 struct mcp3911 *adc = iio_priv(indio_dev);
335 iio_device_unregister(indio_dev);
337 clk_disable_unprepare(adc->clki);
339 regulator_disable(adc->vref);
344 static const struct of_device_id mcp3911_dt_ids[] = {
345 { .compatible = "microchip,mcp3911" },
348 MODULE_DEVICE_TABLE(of, mcp3911_dt_ids);
350 static const struct spi_device_id mcp3911_id[] = {
354 MODULE_DEVICE_TABLE(spi, mcp3911_id);
356 static struct spi_driver mcp3911_driver = {
359 .of_match_table = mcp3911_dt_ids,
361 .probe = mcp3911_probe,
362 .remove = mcp3911_remove,
363 .id_table = mcp3911_id,
365 module_spi_driver(mcp3911_driver);
367 MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson@gmail.com>");
368 MODULE_AUTHOR("Kent Gustavsson <kent@minoris.se>");
369 MODULE_DESCRIPTION("Microchip Technology MCP3911");
370 MODULE_LICENSE("GPL v2");