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/mod_devicetable.h>
14 #include <linux/property.h>
15 #include <linux/regulator/consumer.h>
16 #include <linux/spi/spi.h>
18 #define MCP3911_REG_CHANNEL0 0x00
19 #define MCP3911_REG_CHANNEL1 0x03
20 #define MCP3911_REG_MOD 0x06
21 #define MCP3911_REG_PHASE 0x07
22 #define MCP3911_REG_GAIN 0x09
24 #define MCP3911_REG_STATUSCOM 0x0a
25 #define MCP3911_STATUSCOM_CH1_24WIDTH BIT(4)
26 #define MCP3911_STATUSCOM_CH0_24WIDTH BIT(3)
27 #define MCP3911_STATUSCOM_EN_OFFCAL BIT(2)
28 #define MCP3911_STATUSCOM_EN_GAINCAL BIT(1)
30 #define MCP3911_REG_CONFIG 0x0c
31 #define MCP3911_CONFIG_CLKEXT BIT(1)
32 #define MCP3911_CONFIG_VREFEXT BIT(2)
34 #define MCP3911_REG_OFFCAL_CH0 0x0e
35 #define MCP3911_REG_GAINCAL_CH0 0x11
36 #define MCP3911_REG_OFFCAL_CH1 0x14
37 #define MCP3911_REG_GAINCAL_CH1 0x17
38 #define MCP3911_REG_VREFCAL 0x1a
40 #define MCP3911_CHANNEL(x) (MCP3911_REG_CHANNEL0 + x * 3)
41 #define MCP3911_OFFCAL(x) (MCP3911_REG_OFFCAL_CH0 + x * 6)
43 /* Internal voltage reference in uV */
44 #define MCP3911_INT_VREF_UV 1200000
46 #define MCP3911_REG_READ(reg, id) ((((reg) << 1) | ((id) << 5) | (1 << 0)) & 0xff)
47 #define MCP3911_REG_WRITE(reg, id) ((((reg) << 1) | ((id) << 5) | (0 << 0)) & 0xff)
49 #define MCP3911_NUM_CHANNELS 2
52 struct spi_device *spi;
54 struct regulator *vref;
59 static int mcp3911_read(struct mcp3911 *adc, u8 reg, u32 *val, u8 len)
63 reg = MCP3911_REG_READ(reg, adc->dev_addr);
64 ret = spi_write_then_read(adc->spi, ®, 1, val, len);
69 *val >>= ((4 - len) * 8);
70 dev_dbg(&adc->spi->dev, "reading 0x%x from register 0x%x\n", *val,
75 static int mcp3911_write(struct mcp3911 *adc, u8 reg, u32 val, u8 len)
77 dev_dbg(&adc->spi->dev, "writing 0x%x to register 0x%x\n", val, reg);
79 val <<= (3 - len) * 8;
81 val |= MCP3911_REG_WRITE(reg, adc->dev_addr);
83 return spi_write(adc->spi, &val, len + 1);
86 static int mcp3911_update(struct mcp3911 *adc, u8 reg, u32 mask,
92 ret = mcp3911_read(adc, reg, &tmp, len);
98 return mcp3911_write(adc, reg, val, len);
101 static int mcp3911_read_raw(struct iio_dev *indio_dev,
102 struct iio_chan_spec const *channel, int *val,
103 int *val2, long mask)
105 struct mcp3911 *adc = iio_priv(indio_dev);
108 mutex_lock(&adc->lock);
110 case IIO_CHAN_INFO_RAW:
111 ret = mcp3911_read(adc,
112 MCP3911_CHANNEL(channel->channel), val, 3);
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_UV;
144 ret = IIO_VAL_FRACTIONAL_LOG2;
149 mutex_unlock(&adc->lock);
153 static int mcp3911_write_raw(struct iio_dev *indio_dev,
154 struct iio_chan_spec const *channel, int val,
157 struct mcp3911 *adc = iio_priv(indio_dev);
160 mutex_lock(&adc->lock);
162 case IIO_CHAN_INFO_OFFSET:
169 ret = mcp3911_write(adc, MCP3911_OFFCAL(channel->channel), val,
175 ret = mcp3911_update(adc, MCP3911_REG_STATUSCOM,
176 MCP3911_STATUSCOM_EN_OFFCAL,
177 MCP3911_STATUSCOM_EN_OFFCAL, 2);
182 mutex_unlock(&adc->lock);
186 #define MCP3911_CHAN(idx) { \
187 .type = IIO_VOLTAGE, \
190 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
191 BIT(IIO_CHAN_INFO_OFFSET) | \
192 BIT(IIO_CHAN_INFO_SCALE), \
195 static const struct iio_chan_spec mcp3911_channels[] = {
200 static const struct iio_info mcp3911_info = {
201 .read_raw = mcp3911_read_raw,
202 .write_raw = mcp3911_write_raw,
205 static int mcp3911_config(struct mcp3911 *adc)
207 struct device *dev = &adc->spi->dev;
211 device_property_read_u32(dev, "device-addr", &adc->dev_addr);
212 if (adc->dev_addr > 3) {
213 dev_err(&adc->spi->dev,
214 "invalid device address (%i). Must be in range 0-3.\n",
218 dev_dbg(&adc->spi->dev, "use device address %i\n", adc->dev_addr);
220 ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &configreg, 2);
225 dev_dbg(&adc->spi->dev, "use external voltage reference\n");
226 configreg |= MCP3911_CONFIG_VREFEXT;
228 dev_dbg(&adc->spi->dev,
229 "use internal voltage reference (1.2V)\n");
230 configreg &= ~MCP3911_CONFIG_VREFEXT;
234 dev_dbg(&adc->spi->dev, "use external clock as clocksource\n");
235 configreg |= MCP3911_CONFIG_CLKEXT;
237 dev_dbg(&adc->spi->dev,
238 "use crystal oscillator as clocksource\n");
239 configreg &= ~MCP3911_CONFIG_CLKEXT;
242 return mcp3911_write(adc, MCP3911_REG_CONFIG, configreg, 2);
245 static int mcp3911_probe(struct spi_device *spi)
247 struct iio_dev *indio_dev;
251 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
255 adc = iio_priv(indio_dev);
258 adc->vref = devm_regulator_get_optional(&adc->spi->dev, "vref");
259 if (IS_ERR(adc->vref)) {
260 if (PTR_ERR(adc->vref) == -ENODEV) {
263 dev_err(&adc->spi->dev,
264 "failed to get regulator (%ld)\n",
266 return PTR_ERR(adc->vref);
270 ret = regulator_enable(adc->vref);
275 adc->clki = devm_clk_get(&adc->spi->dev, NULL);
276 if (IS_ERR(adc->clki)) {
277 if (PTR_ERR(adc->clki) == -ENOENT) {
280 dev_err(&adc->spi->dev,
281 "failed to get adc clk (%ld)\n",
283 ret = PTR_ERR(adc->clki);
287 ret = clk_prepare_enable(adc->clki);
289 dev_err(&adc->spi->dev,
290 "Failed to enable clki: %d\n", ret);
295 ret = mcp3911_config(adc);
299 indio_dev->name = spi_get_device_id(spi)->name;
300 indio_dev->modes = INDIO_DIRECT_MODE;
301 indio_dev->info = &mcp3911_info;
302 spi_set_drvdata(spi, indio_dev);
304 indio_dev->channels = mcp3911_channels;
305 indio_dev->num_channels = ARRAY_SIZE(mcp3911_channels);
307 mutex_init(&adc->lock);
309 ret = iio_device_register(indio_dev);
316 clk_disable_unprepare(adc->clki);
319 regulator_disable(adc->vref);
324 static void mcp3911_remove(struct spi_device *spi)
326 struct iio_dev *indio_dev = spi_get_drvdata(spi);
327 struct mcp3911 *adc = iio_priv(indio_dev);
329 iio_device_unregister(indio_dev);
331 clk_disable_unprepare(adc->clki);
333 regulator_disable(adc->vref);
336 static const struct of_device_id mcp3911_dt_ids[] = {
337 { .compatible = "microchip,mcp3911" },
340 MODULE_DEVICE_TABLE(of, mcp3911_dt_ids);
342 static const struct spi_device_id mcp3911_id[] = {
346 MODULE_DEVICE_TABLE(spi, mcp3911_id);
348 static struct spi_driver mcp3911_driver = {
351 .of_match_table = mcp3911_dt_ids,
353 .probe = mcp3911_probe,
354 .remove = mcp3911_remove,
355 .id_table = mcp3911_id,
357 module_spi_driver(mcp3911_driver);
359 MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson@gmail.com>");
360 MODULE_AUTHOR("Kent Gustavsson <kent@minoris.se>");
361 MODULE_DESCRIPTION("Microchip Technology MCP3911");
362 MODULE_LICENSE("GPL v2");