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Subject[PATCH 1/3] iio: adc: add support for mcp3911
Date
MCP3911 is a dual channel Analog Front End (AFE) containing two
synchronous sampling delta-sigma Analog-to-Digital Converters (ADC).

Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Signed-off-by: Kent Gustavsson <kent@minoris.se>
---
drivers/iio/adc/Kconfig | 10 ++
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/mcp3911.c | 444 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 455 insertions(+)
create mode 100644 drivers/iio/adc/mcp3911.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 15606f237480..f9a41fa96fcc 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -501,6 +501,16 @@ config MCP3422
This driver can also be built as a module. If so, the module will be
called mcp3422.

+config MCP3911
+ tristate "Microchip Technology MCP3911 driver"
+ depends on SPI
+ help
+ Say yes here to build support for Microchip Technology's MCP3911
+ analog to digital converter.
+
+ This driver can also be built as a module. If so, the module will be
+ called mcp3911.
+
config MEDIATEK_MT6577_AUXADC
tristate "MediaTek AUXADC driver"
depends on ARCH_MEDIATEK || COMPILE_TEST
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 28a9423997f3..3cfebfff7d26 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -47,6 +47,7 @@ obj-$(CONFIG_MAX1363) += max1363.o
obj-$(CONFIG_MAX9611) += max9611.o
obj-$(CONFIG_MCP320X) += mcp320x.o
obj-$(CONFIG_MCP3422) += mcp3422.o
+obj-$(CONFIG_MCP3911) += mcp3911.o
obj-$(CONFIG_MEDIATEK_MT6577_AUXADC) += mt6577_auxadc.o
obj-$(CONFIG_MEN_Z188_ADC) += men_z188_adc.o
obj-$(CONFIG_MESON_SARADC) += meson_saradc.o
diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
new file mode 100644
index 000000000000..be74cb15827b
--- /dev/null
+++ b/drivers/iio/adc/mcp3911.c
@@ -0,0 +1,444 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for Microchip MCP3911, Two-channel Analog Front End
+ *
+ * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com>
+ * Copyright (C) 2018 Kent Gustavsson <kent@minoris.se>
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#define MCP3911_REG_CHANNEL0 0x00
+#define MCP3911_REG_CHANNEL1 0x03
+#define MCP3911_REG_MOD 0x06
+#define MCP3911_REG_PHASE 0x07
+
+#define MCP3911_REG_GAIN 0x09
+#define MCP3911_GAIN_MASK(ch) (0x7 << 3*ch)
+#define MCP3911_GAIN_VAL(ch, val) ((val << 3*ch) & MCP3911_GAIN_MASK(ch))
+
+#define MCP3911_REG_STATUSCOM 0x0a
+#define MCP3911_STATUSCOM_CH1_24WIDTH BIT(4)
+#define MCP3911_STATUSCOM_CH0_24WIDTH BIT(3)
+#define MCP3911_STATUSCOM_EN_OFFCAL BIT(2)
+#define MCP3911_STATUSCOM_EN_GAINCAL BIT(1)
+
+#define MCP3911_REG_CONFIG 0x0c
+#define MCP3911_CONFIG_CLKEXT BIT(1)
+#define MCP3911_CONFIG_VREFEXT BIT(2)
+
+#define MCP3911_REG_OFFCAL_CH0 0x0e
+#define MCP3911_REG_GAINCAL_CH0 0x11
+#define MCP3911_REG_OFFCAL_CH1 0x14
+#define MCP3911_REG_GAINCAL_CH1 0x17
+#define MCP3911_REG_VREFCAL 0x1a
+
+#define MCP3911_CHANNEL(x) (MCP3911_REG_CHANNEL0 + x * 3)
+#define MCP3911_OFFCAL(x) (MCP3911_REG_OFFCAL_CH0 + x * 6)
+#define MCP3911_GAINCAL(x) (MCP3911_REG_GAINCAL_CH0 + x * 6)
+
+
+/* Internal voltage reference in uV */
+#define MCP3911_INT_VREF_UV 1200000
+
+#define REG_READ(reg, id) (((reg << 1) | (id << 5) | (1 << 0)) & 0xff)
+#define REG_WRITE(reg, id) (((reg << 1) | (id << 5) | (0 << 0)) & 0xff)
+
+#define MCP3911_NUM_CHANNELS 2
+
+
+struct mcp3911 {
+ struct spi_device *spi;
+ struct device_node *np;
+ struct mutex lock;
+
+ u32 gain[MCP3911_NUM_CHANNELS];
+ u32 width[MCP3911_NUM_CHANNELS];
+
+ u32 dev_addr;
+ bool vrefext;
+ struct regulator *vref;
+};
+
+static int mcp3911_read(struct mcp3911 *adc, u8 reg, u32 *val, u8 len)
+{
+ int ret;
+
+ reg = REG_READ(reg, adc->dev_addr);
+ ret = spi_write_then_read(adc->spi, &reg, 1, val, len);
+ if (ret < 0)
+ return ret;
+
+ *val <<= ((4-len)*8);
+ be32_to_cpus(val);
+ dev_dbg(&adc->spi->dev, "Reading 0x%x from register 0x%x\n", *val,
+ reg>>1);
+ return ret;
+}
+
+static int mcp3911_write(struct mcp3911 *adc, u8 reg, u32 val, u8 len)
+{
+ dev_dbg(&adc->spi->dev, "Writing 0x%x to register 0x%x\n", val, reg);
+
+ cpu_to_be32s(&val);
+ val >>= (3-len)*8;
+ val |= REG_WRITE(reg, adc->dev_addr);
+
+ return spi_write(adc->spi, &val, len+1);
+}
+
+static int mcp3911_update(struct mcp3911 *adc, u8 reg, u32 mask,
+ u32 val, u8 len)
+{
+ u32 tmp;
+ int ret;
+
+ ret = mcp3911_read(adc, reg, &tmp, len);
+ if (ret)
+ return ret;
+
+ val &= mask;
+ val |= tmp & ~mask;
+ return mcp3911_write(adc, reg, val, len);
+}
+
+static int mcp3911_get_hwgain(struct mcp3911 *adc, u8 channel, u32 *val)
+{
+ int ret = mcp3911_read(adc, MCP3911_REG_GAIN, val, 1);
+
+ if (ret)
+ return ret;
+
+ *val >>= channel*3;
+ *val &= 0x07;
+ *val = (1 << *val);
+
+ return 0;
+}
+
+static int mcp3911_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *channel, int *val,
+ int *val2, long mask)
+{
+ struct mcp3911 *adc = iio_priv(indio_dev);
+ int ret = -EINVAL;
+
+ mutex_lock(&adc->lock);
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ ret = mcp3911_read(adc,
+ MCP3911_CHANNEL(channel->channel), val, 3);
+ if (ret)
+ goto out;
+
+ ret = IIO_VAL_INT;
+ break;
+
+ case IIO_CHAN_INFO_OFFSET:
+ ret = mcp3911_read(adc,
+ MCP3911_OFFCAL(channel->channel), val, 3);
+ if (ret)
+ goto out;
+
+ ret = IIO_VAL_INT;
+ break;
+
+ case IIO_CHAN_INFO_HARDWAREGAIN:
+ ret = mcp3911_get_hwgain(adc, channel->channel, val);
+ if (ret)
+ goto out;
+
+ ret = IIO_VAL_INT;
+ break;
+
+ case IIO_CHAN_INFO_SCALE:
+ if (adc->vrefext) {
+ ret = regulator_get_voltage(adc->vref);
+ if (ret < 0) {
+ dev_err(indio_dev->dev.parent,
+ "failed to get vref voltage:%d\n", ret);
+ goto out;
+ }
+
+ *val = ret / 1000;
+ } else {
+ *val = MCP3911_INT_VREF_UV;
+ }
+
+ /* apply with gain value */
+ *val /= adc->gain[channel->channel];
+ *val2 = adc->width[channel->channel];
+
+ ret = IIO_VAL_FRACTIONAL_LOG2;
+ break;
+ }
+
+out:
+ mutex_unlock(&adc->lock);
+
+ return ret;
+}
+
+static int mcp3911_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *channel, int val,
+ int val2, long mask)
+{
+ struct mcp3911 *adc = iio_priv(indio_dev);
+ int ret = -EINVAL;
+
+ mutex_lock(&adc->lock);
+ switch (mask) {
+ case IIO_CHAN_INFO_OFFSET:
+
+ /* Write offset */
+ ret = mcp3911_write(adc, MCP3911_OFFCAL(channel->channel), val,
+ 3);
+ if (ret)
+ goto out;
+
+ /* Enable offset*/
+ ret = mcp3911_update(adc, MCP3911_REG_STATUSCOM,
+ MCP3911_STATUSCOM_EN_OFFCAL,
+ MCP3911_STATUSCOM_EN_OFFCAL, 2);
+ if (ret)
+ goto out;
+
+ break;
+
+ case IIO_CHAN_INFO_HARDWAREGAIN:
+ if (!is_power_of_2(val) && val <= 32) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ adc->gain[channel->channel] = val;
+
+ val = ilog2(val);
+ ret = mcp3911_update(adc, MCP3911_REG_GAIN,
+ MCP3911_GAIN_MASK(channel->channel),
+ MCP3911_GAIN_VAL(channel->channel,
+ val), 1);
+ break;
+ }
+
+out:
+ mutex_unlock(&adc->lock);
+
+ return ret;
+}
+
+static const struct iio_chan_spec mcp3911_channels[] = {
+ {
+ .type = IIO_VOLTAGE,
+ .indexed = 1,
+ .channel = 0,
+ .address = MCP3911_REG_CHANNEL0,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+ BIT(IIO_CHAN_INFO_OFFSET) |
+ BIT(IIO_CHAN_INFO_SCALE) |
+ BIT(IIO_CHAN_INFO_HARDWAREGAIN),
+ },
+ {
+ .type = IIO_VOLTAGE,
+ .indexed = 1,
+ .channel = 1,
+ .address = MCP3911_REG_CHANNEL1,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+ BIT(IIO_CHAN_INFO_OFFSET) |
+ BIT(IIO_CHAN_INFO_SCALE) |
+ BIT(IIO_CHAN_INFO_HARDWAREGAIN),
+ },
+};
+
+static const struct iio_info mcp3911_info = {
+ .read_raw = mcp3911_read_raw,
+ .write_raw = mcp3911_write_raw,
+};
+
+static int mcp3911_config_of(struct mcp3911 *adc)
+{
+ u32 configreg;
+ u32 statuscomreg;
+ int ret;
+
+ of_property_read_u32(adc->np, "device-addr", &adc->dev_addr);
+ if (adc->dev_addr > 3) {
+ dev_err(&adc->spi->dev,
+ "invalid device address (%i). Must be in range 0-3.\n",
+ adc->dev_addr);
+ return -EINVAL;
+ }
+ dev_dbg(&adc->spi->dev, "use device address %i\n", adc->dev_addr);
+
+ ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &configreg, 2);
+ if (ret)
+ return ret;
+
+ adc->vrefext = of_property_read_bool(adc->np, "external-vref");
+ if (adc->vrefext) {
+ dev_dbg(&adc->spi->dev, "use external voltage reference\n");
+ configreg |= MCP3911_CONFIG_VREFEXT;
+
+ } else {
+ dev_dbg(&adc->spi->dev, "use internal voltage reference (1.2V)\n");
+ configreg &= ~MCP3911_CONFIG_VREFEXT;
+ }
+
+ if (of_property_read_bool(adc->np, "external-clock")) {
+ dev_dbg(&adc->spi->dev, "use external clock as clocksource\n");
+ configreg |= MCP3911_CONFIG_CLKEXT;
+ } else {
+ dev_dbg(&adc->spi->dev, "use crystal oscillator as clocksource\n");
+ configreg &= ~MCP3911_CONFIG_CLKEXT;
+ }
+
+ ret = mcp3911_write(adc, MCP3911_REG_CONFIG, configreg, 2);
+ if (ret)
+ return ret;
+
+
+ ret = mcp3911_read(adc, MCP3911_REG_STATUSCOM, &statuscomreg, 2);
+ if (ret)
+ return ret;
+
+
+ of_property_read_u32(adc->np, "ch0-width", &adc->width[0]);
+ switch (adc->width[0]) {
+ case 24:
+ statuscomreg &= ~MCP3911_STATUSCOM_CH0_24WIDTH;
+ dev_dbg(&adc->spi->dev, "set channel 0 into 24bit mode\n");
+ break;
+ case 16:
+ statuscomreg |= MCP3911_STATUSCOM_CH0_24WIDTH;
+ dev_dbg(&adc->spi->dev, "set channel 0 into 16bit mode\n");
+ break;
+ default:
+ adc->width[0] = 24;
+ dev_info(&adc->spi->dev, "invalid width for channel 0. Use 24bit.\n");
+ break;
+ }
+
+ of_property_read_u32(adc->np, "ch1-width", &adc->width[1]);
+ switch (adc->width[1]) {
+ case 24:
+ statuscomreg &= ~MCP3911_STATUSCOM_CH1_24WIDTH;
+ dev_dbg(&adc->spi->dev, "set channel 1 into 24bit mode\n");
+ break;
+ case 16:
+ statuscomreg |= MCP3911_STATUSCOM_CH1_24WIDTH;
+ dev_dbg(&adc->spi->dev, "set channel 1 into 16bit mode\n");
+ break;
+ default:
+ adc->width[1] = 24;
+ dev_info(&adc->spi->dev, "invalid width for channel 1. Use 24bit.\n");
+ break;
+ }
+
+ return mcp3911_write(adc, MCP3911_REG_STATUSCOM, statuscomreg, 2);
+}
+
+static int mcp3911_probe(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev;
+ struct mcp3911 *adc;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ adc = iio_priv(indio_dev);
+ adc->spi = spi;
+ adc->np = spi->dev.of_node;
+
+ ret = mcp3911_config_of(adc);
+ if (ret)
+ return ret;
+
+ if (adc->vrefext) {
+ adc->vref = devm_regulator_get(&adc->spi->dev, "vref");
+ if (IS_ERR(adc->vref))
+ return PTR_ERR(adc->vref);
+
+ ret = regulator_enable(adc->vref);
+ if (ret < 0)
+ return ret;
+ }
+
+ /* Store gain values to better calculate scale values */
+ mcp3911_get_hwgain(adc, 0, &adc->gain[0]);
+ mcp3911_get_hwgain(adc, 1, &adc->gain[1]);
+
+ indio_dev->dev.parent = &spi->dev;
+ indio_dev->dev.of_node = spi->dev.of_node;
+ indio_dev->name = spi_get_device_id(spi)->name;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->info = &mcp3911_info;
+ spi_set_drvdata(spi, indio_dev);
+
+ indio_dev->channels = mcp3911_channels;
+ indio_dev->num_channels = ARRAY_SIZE(mcp3911_channels);
+
+ mutex_init(&adc->lock);
+
+ ret = iio_device_register(indio_dev);
+ if (ret)
+ goto reg_disable;
+
+ return ret;
+
+reg_disable:
+ if (adc->vref)
+ regulator_disable(adc->vref);
+
+ return ret;
+}
+
+static int mcp3911_remove(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev = spi_get_drvdata(spi);
+ struct mcp3911 *adc = iio_priv(indio_dev);
+
+ iio_device_unregister(indio_dev);
+
+ if (adc->vref)
+ regulator_disable(adc->vref);
+
+ return 0;
+}
+
+#if defined(CONFIG_OF)
+static const struct of_device_id mcp3911_dt_ids[] = {
+ { .compatible = "microchip,mcp3911" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, mcp3911_dt_ids);
+#endif
+
+static const struct spi_device_id mcp3911_id[] = {
+ { "mcp3911", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(spi, mcp3911_id);
+
+static struct spi_driver mcp3911_driver = {
+ .driver = {
+ .name = "mcp3911",
+ .of_match_table = of_match_ptr(mcp3911_dt_ids),
+ },
+ .probe = mcp3911_probe,
+ .remove = mcp3911_remove,
+ .id_table = mcp3911_id,
+};
+module_spi_driver(mcp3911_driver);
+
+MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson@gmail.com>");
+MODULE_AUTHOR("Kent Gustavsson <kent@minoris.se>");
+MODULE_DESCRIPTION("Microchip Technology MCP3911");
+MODULE_LICENSE("GPL v2");
--
2.11.0.rc2
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