BeagleV-Fire-ubuntu/patches/linux/0004-ADC-Add-Microchip-MCP356X-driver.patch

From deadef387eed1bc60c8d2570e86a9bd0b4b196b4 Mon Sep 17 00:00:00 2001
From: vauban353 <vauban353@gmail.com>
Date: Fri, 16 Jun 2023 16:05:01 +0100
Subject: [PATCH 4/8] ADC: Add Microchip MCP356X driver.

---
 drivers/iio/adc/Kconfig   |   10 +
 drivers/iio/adc/Makefile  |    1 +
 drivers/iio/adc/mcp356x.c | 1396 +++++++++++++++++++++++++++++++++++++
 3 files changed, 1407 insertions(+)
 create mode 100644 drivers/iio/adc/mcp356x.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 48763d6a8..6c6b62a7f 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -741,6 +741,16 @@ config MCP3911
 	  This driver can also be built as a module. If so, the module will be
 	  called mcp3911.
 
+config MCP356X
+	tristate "Microchip Technology MCP356X driver"
+	depends on SPI
+	help
+	  Say yes here to build support for Microchip Technology's MCP356X
+	  analog to digital converter.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called mcp356x.
+
 config MEDIATEK_MT6360_ADC
 	tristate "Mediatek MT6360 ADC driver"
 	depends on MFD_MT6360
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index d5ca37205..5b3f027ac 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -68,6 +68,7 @@ obj-$(CONFIG_MAX9611) += max9611.o
 obj-$(CONFIG_MCP320X) += mcp320x.o
 obj-$(CONFIG_MCP3422) += mcp3422.o
 obj-$(CONFIG_MCP3911) += mcp3911.o
+obj-$(CONFIG_MCP356X) += mcp356x.o
 obj-$(CONFIG_MEDIATEK_MT6360_ADC) += mt6360-adc.o
 obj-$(CONFIG_MEDIATEK_MT6577_AUXADC) += mt6577_auxadc.o
 obj-$(CONFIG_MEN_Z188_ADC) += men_z188_adc.o
diff --git a/drivers/iio/adc/mcp356x.c b/drivers/iio/adc/mcp356x.c
new file mode 100644
index 000000000..22d59413d
--- /dev/null
+++ b/drivers/iio/adc/mcp356x.c
@@ -0,0 +1,1396 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * IIO driver for MCP356X/MCP356XR and MCP346X/MCP346XR series ADC chip family
+ *
+ * Copyright (C) 2022-2023 Microchip Technology Inc. and its subsidiaries
+ *
+ * Author: Marius Cristea <marius.cristea@microchip.com>
+ *
+ * Datasheet for MCP3561, MCP3562, MCP3564 can be found here:
+ * https://ww1.microchip.com/downloads/aemDocuments/documents/MSLD/ProductDocuments/DataSheets/MCP3561-2-4-Family-Data-Sheet-DS20006181C.pdf
+ * Datasheet for MCP3561R, MCP3562R, MCP3564R can be found here:
+ * https://ww1.microchip.com/downloads/aemDocuments/documents/APID/ProductDocuments/DataSheets/MCP3561_2_4R-Data-Sheet-DS200006391C.pdf
+ * Datasheet for MCP3461, MCP3462, MCP3464 can be found here:
+ * https://ww1.microchip.com/downloads/aemDocuments/documents/APID/ProductDocuments/DataSheets/MCP3461-2-4-Two-Four-Eight-Channel-153.6-ksps-Low-Noise-16-Bit-Delta-Sigma-ADC-Data-Sheet-20006180D.pdf
+ * Datasheet for MCP3461R, MCP3462R, MCP3464R can be found here:
+ * https://ww1.microchip.com/downloads/aemDocuments/documents/APID/ProductDocuments/DataSheets/MCP3461-2-4R-Family-Data-Sheet-DS20006404C.pdf
+ *
+ */
+
+#include <linux/acpi.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/iopoll.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+#include <linux/util_macros.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define MCP356X_ADCDATA		0x00
+#define MCP356X_CONFIG0		0x01
+#define MCP356X_CONFIG1		0x02
+#define MCP356X_CONFIG2		0x03
+#define MCP356X_CONFIG3		0x04
+#define MCP356X_IRQ		0x05
+#define MCP356X_MUX		0x06
+#define MCP356X_SCAN		0x07
+#define MCP356X_TIMER		0x08
+#define MCP356X_OFFSETCAL	0x09
+#define MCP356X_GAINCAL		0x0A
+#define MCP356X_RESERVED_B	0x0B
+#define MCP356X_RESERVED_C	0x0C
+#define MCP356X_LOCK		0x0D
+#define MCP356X_RESERVED_E	0x0E
+#define MCP356X_CRCCFG		0x0F
+
+#define MCP356X_FAST_CMD_CTRL	0
+#define MCP356X_RD_CTRL		BIT(0)
+#define MCP356X_WRT_CTRL	BIT(1)
+
+#define MCP356X_FULL_RESET_CMD	GENMASK(3, 1)
+
+#define MCP3461_HW_ID		BIT(3)
+#define MCP3462_HW_ID		0x0009
+#define MCP3464_HW_ID		0x000B
+
+#define MCP3561_HW_ID		GENMASK(3, 2)
+#define MCP3562_HW_ID		0x000D
+#define MCP3564_HW_ID		GENMASK(3, 0)
+#define MCP356X_HW_ID_MASK	GENMASK(3, 0)
+
+#define MCP356XR_INT_VREF_MV	2400
+
+/* MUX_VIN Input Selection
+ */
+#define MCP356X_INTERNAL_VCM	GENMASK(3, 0)
+#define MCP356X_TEMP_DIODE_M	GENMASK(3, 1)
+#define MCP356X_TEMP_DIODE_P	0b1101
+#define MCP356X_REFIN_NEG	GENMASK(3, 2)
+#define MCP356X_REFIN_POZ	0b1011
+#define MCP356X_RESERVED	0b1010 /* do not use */
+#define MCP356X_AVDD		0b1001
+#define MCP356X_AGND		BIT(3)
+#define MCP356X_CH7		GENMASK(2, 0)
+#define MCP356X_CH6		GENMASK(2, 1)
+#define MCP356X_CH5		0b0101
+#define MCP356X_CH4		BIT(2)
+#define MCP356X_CH3		GENMASK(1, 0)
+#define MCP356X_CH2		BIT(1)
+#define MCP356X_CH1		BIT(0)
+#define MCP356X_CH0		0
+
+#define MCP356X_ADC_MODE_MASK			GENMASK(1, 0)
+
+#define MCP356X_ADC_DEFAULT_MODE		0
+#define MCP356X_ADC_SHUTDOWN_MODE		BIT(0)
+#define MCP356X_ADC_STANDBY			BIT(1)
+#define MCP356X_ADC_CONVERSION_MODE		GENMASK(1, 0)
+
+#define MCP356X_DATA_READY_MASK			BIT(6)
+
+#define MCP356X_OVERSAMPLING_RATIO_32		0
+#define MCP356X_OVERSAMPLING_RATIO_64		BIT(0)
+#define MCP356X_OVERSAMPLING_RATIO_128		BIT(1)
+#define MCP356X_OVERSAMPLING_RATIO_256		GENMASK(1, 0)
+#define MCP356X_OVERSAMPLING_RATIO_512		BIT(2)
+#define MCP356X_OVERSAMPLING_RATIO_1024		0x05
+#define MCP356X_OVERSAMPLING_RATIO_2048		GENMASK(2, 1)
+#define MCP356X_OVERSAMPLING_RATIO_4096		GENMASK(2, 0)
+#define MCP356X_OVERSAMPLING_RATIO_8192		BIT(3)
+#define MCP356X_OVERSAMPLING_RATIO_16384	0x09
+#define MCP356X_OVERSAMPLING_RATIO_20480	0x0A
+#define MCP356X_OVERSAMPLING_RATIO_24576	0x0B
+#define MCP356X_OVERSAMPLING_RATIO_40960	0x0C
+#define MCP356X_OVERSAMPLING_RATIO_49152	0x0D
+#define MCP356X_OVERSAMPLING_RATIO_81920	GENMASK(3, 1)
+#define MCP356X_OVERSAMPLING_RATIO_98304	GENMASK(3, 0)
+
+#define MCP356X_OVERSAMPLING_RATIO_MASK		GENMASK(5, 2)
+#define MCP356X_OVERSAMPLING_RATIO_SHIFT	0x02
+
+#define MCP356X_HARDWARE_GAIN_MASK		GENMASK(5, 3)
+#define MCP356X_HARDWARE_GAIN_SHIFT		0x03
+#define MCP356X_DEFAULT_HARDWARE_GAIN		BIT(1)
+
+#define MCP356X_CS_SEL_0_0_uA			0x0
+#define MCP356X_CS_SEL_0_9_uA			BIT(0)
+#define MCP356X_CS_SEL_3_7_uA			BIT(1)
+#define MCP356X_CS_SEL_15_uA			GENMASK(1, 0)
+
+#define MCP356X_CS_SEL_MASK			GENMASK(3, 2)
+
+#define MCP356X_BOOST_CURRENT_x0_50		0
+#define MCP356X_BOOST_CURRENT_x0_66		BIT(0)
+#define MCP356X_BOOST_CURRENT_x1_00		BIT(1)
+#define MCP356X_BOOST_CURRENT_x2_00		GENMASK(1, 0)
+
+#define MCP356X_BOOST_CURRENT_MASK		GENMASK(7, 6)
+
+/* Auto-Zeroing MUX Setting */
+#define MCP356X_AZ_MUX_MASK			BIT(2)
+/* Auto-Zeroing REF Setting */
+#define MCP356X_AZ_REF_MASK			BIT(1)
+
+#define MCP356X_SHARED_DEVATTRS_COUNT		1
+#define MCP356X_PARTICULAR_DEVATTRS_COUNT	1
+
+#define MAX_HWGAIN				64000
+
+#define MCP356X_DATA_READY_TIMEOUT_MS		2000
+
+enum mcp356x_ids {
+	mcp3461,
+	mcp3462,
+	mcp3464,
+	mcp3461r,
+	mcp3462r,
+	mcp3464r,
+	mcp3561,
+	mcp3562,
+	mcp3564,
+	mcp3561r,
+	mcp3562r,
+	mcp3564r,
+};
+
+static const unsigned int mcp356x_oversampling_avail[16] = {
+	[MCP356X_OVERSAMPLING_RATIO_32] = 32,
+	[MCP356X_OVERSAMPLING_RATIO_64] = 64,
+	[MCP356X_OVERSAMPLING_RATIO_128] = 128,
+	[MCP356X_OVERSAMPLING_RATIO_256] = 256,
+	[MCP356X_OVERSAMPLING_RATIO_512] = 512,
+	[MCP356X_OVERSAMPLING_RATIO_1024] = 1024,
+	[MCP356X_OVERSAMPLING_RATIO_2048] = 2048,
+	[MCP356X_OVERSAMPLING_RATIO_4096] = 4096,
+	[MCP356X_OVERSAMPLING_RATIO_8192] = 8192,
+	[MCP356X_OVERSAMPLING_RATIO_16384] = 16384,
+	[MCP356X_OVERSAMPLING_RATIO_20480] = 20480,
+	[MCP356X_OVERSAMPLING_RATIO_24576] = 24576,
+	[MCP356X_OVERSAMPLING_RATIO_40960] = 40960,
+	[MCP356X_OVERSAMPLING_RATIO_49152] = 49152,
+	[MCP356X_OVERSAMPLING_RATIO_81920] = 81920,
+	[MCP356X_OVERSAMPLING_RATIO_98304] = 98304
+};
+
+/*
+ * Current Source/Sink Selection Bits for Sensor Bias (source on VIN+/sink on VIN-)
+ */
+static const char * const mcp356x_current_bias_avail[] = {
+	[MCP356X_CS_SEL_0_0_uA] = "no_current(default)",
+	[MCP356X_CS_SEL_0_9_uA] = "0.9_uA",
+	[MCP356X_CS_SEL_3_7_uA] = "3.7_uA",
+	[MCP356X_CS_SEL_15_uA] = "15_uA",
+};
+
+/*
+ * BOOST[1:0]: ADC Bias Current Selection
+ */
+static const char * const mcp356x_boost_current_avail[] = {
+	[MCP356X_BOOST_CURRENT_x0_50] = "x0.5",
+	[MCP356X_BOOST_CURRENT_x0_66] = "x0.66",
+	[MCP356X_BOOST_CURRENT_x1_00] = "x1_(default)",
+	[MCP356X_BOOST_CURRENT_x2_00] = "x2",
+};
+
+/*
+ * Calibration bias values
+ */
+static const int mcp356x_calib_bias[] = {
+	-8388608,	/* min: -2^23		*/
+	 1,		/* step: 1		*/
+	 8388607	/* max:  2^23 - 1	*/
+};
+
+/*
+ * Calibration scale values
+ * The Gain Error Calibration register (GAINCAL) is an
+ * unsigned 24-bit register that holds the digital gain error
+ * calibration value, GAINCAL which could be calculated by
+ * GAINCAL (V/V) = (GAINCAL[23:0])/8388608
+ * The gain error calibration value range in equivalent voltage is [0; 2-2^(-23)]
+ */
+static const unsigned int mcp356x_calib_scale[] = {
+		0,	/* min:  0		*/
+		1,	/* step: 1/8388608	*/
+	 16777215	/* max:  2 - 2^(-23)	*/
+};
+
+/* Programmable hardware gain x1/3, x1, x2, x4, x8, x16, x32, x64 */
+static const int mcp356x_hwgain_frac[] = {
+	3,
+	10,
+	1,
+	1,
+	2,
+	1,
+	4,
+	1,
+	8,
+	1,
+	16,
+	1,
+	32,
+	1,
+	64,
+	1
+};
+
+static const int mcp356x_hwgain[] = {
+	300,
+	1000,
+	2000,
+	4000,
+	8000,
+	16000,
+	32000,
+	64000
+};
+
+/**
+ * struct mcp356x_chip_info - chip specific data
+ * @channels:		struct iio_chan_spec matching the device's capabilities
+ * @num_channels:	number of channels
+ * @int_vref_uv:	internal voltage reference value in microVolts
+ * @has_vref:		Does the ADC has an internal voltage reference?
+ */
+struct mcp356x_chip_info {
+	const struct	iio_chan_spec *channels;
+	unsigned int	num_channels;
+	unsigned int	int_vref_uv;
+	bool		has_vref;
+};
+
+/**
+ * struct mcp356x_state - working data for a ADC device
+ * @chip_info:		chip specific data
+ * @mcp356x_info:	information about iio device
+ * @spi:		SPI device structure
+ * @vref:		The regulator device used as a voltage reference in case
+ *			external voltage reference is used
+ * @vref_mv:		voltage reference value in miliVolts
+ * @lock:		mutex to prevent concurrent reads/writes
+ * @dev_addr:		hardware device address
+ * @oversampling:	the index inside oversampling list of the ADC
+ * @hwgain:		the index inside hardware gain list of the ADC
+ * @calib_bias:		calibration bias value
+ * @calib_scale:	calibration scale value
+ * @current_boost_mode:	the index inside current boost list of the ADC
+ * @current_bias_mode:	the index inside current bias list of the ADC
+ * @auto_zeroing_mux:	set if ADC auto-zeroing algorithm is enabled
+ * @auto_zeroing_ref:	set if ADC auto-Zeroing Reference Buffer Setting is enabled
+ */
+struct mcp356x_state {
+	const struct mcp356x_chip_info *chip_info;
+	struct iio_info		mcp356x_info;
+	struct spi_device	*spi;
+	struct regulator	*vref;
+	unsigned short		vref_mv;
+	struct mutex		lock; /*lock to prevent concurrent reads/writes */
+	u8			dev_addr;
+	unsigned int		oversampling;
+	unsigned int		hwgain;
+	int			calib_bias;
+	int			calib_scale;
+	unsigned int		current_boost_mode;
+	unsigned int		current_bias_mode;
+	bool			auto_zeroing_mux;
+	bool			auto_zeroing_ref;
+};
+
+static inline u8 mcp356x_reg_write(u8 chip_addr, u8 reg)
+{
+	return ((chip_addr << 6) | (reg << 2) | MCP356X_WRT_CTRL);
+}
+
+static inline u8 mcp356x_reg_read(u8 chip_addr, u8 reg)
+{
+	return ((chip_addr << 6) | (reg << 2) | MCP356X_RD_CTRL);
+}
+
+static inline u8 mcp356x_reg_fast_cmd(u8 chip_addr, u8 cmd)
+{
+	return ((chip_addr << 6) | (cmd << 2));
+}
+
+static int mcp356x_read(struct mcp356x_state *adc, u8 reg, u32 *val, u8 len)
+{
+	int ret;
+	u8 tmp_reg;
+
+	tmp_reg = mcp356x_reg_read(adc->dev_addr, reg);
+
+	ret = spi_write_then_read(adc->spi, &tmp_reg, 1, val, len);
+
+	be32_to_cpus(val);
+	*val >>= ((4 - len) * 8);
+
+	return ret;
+}
+
+static int mcp356x_write(struct mcp356x_state *adc, u8 reg, u32 val, u8 len)
+{
+	val |= (mcp356x_reg_write(adc->dev_addr, reg) << (len * 8));
+	val <<= (3 - len) * 8;
+	cpu_to_be32s(&val);
+
+	return spi_write(adc->spi, &val, len + 1);
+}
+
+static int mcp356x_fast_cmd(struct mcp356x_state *adc, u8 fast_cmd)
+{
+	u8 val;
+
+	val = mcp356x_reg_fast_cmd(adc->dev_addr, fast_cmd);
+
+	return spi_write(adc->spi, &val, 1);
+}
+
+static int mcp356x_update(struct mcp356x_state *adc, u8 reg, u32 mask, u32 val,
+			  u8 len)
+{
+	u32 tmp;
+	int ret;
+
+	ret = mcp356x_read(adc, reg, &tmp, len);
+
+	if (ret == 0) {
+		val &= mask;
+		val |= tmp & ~mask;
+		ret = mcp356x_write(adc, reg, val, len);
+	}
+
+	return ret;
+}
+
+/* Custom IIO Device Attributes */
+static int mcp356x_set_current_boost_mode(struct iio_dev *indio_dev,
+					  const struct iio_chan_spec *chan,
+					  unsigned int mode)
+{
+	struct mcp356x_state *adc = iio_priv(indio_dev);
+	int ret;
+
+	dev_dbg(&indio_dev->dev, "%s: %d\n", __func__, mode);
+
+	mutex_lock(&adc->lock);
+	ret = mcp356x_update(adc, MCP356X_CONFIG2, MCP356X_BOOST_CURRENT_MASK,
+			     mode, 1);
+
+	if (ret)
+		dev_err(&indio_dev->dev, "Failed to configure CONFIG2 register\n");
+	else
+		adc->current_boost_mode = mode;
+
+	mutex_unlock(&adc->lock);
+
+	return ret;
+}
+
+static int mcp356x_get_current_boost_mode(struct iio_dev *indio_dev,
+					  const struct iio_chan_spec *chan)
+{
+	struct mcp356x_state *adc = iio_priv(indio_dev);
+
+	return adc->current_boost_mode;
+}
+
+static int mcp356x_set_current_bias_mode(struct iio_dev *indio_dev,
+					 const struct iio_chan_spec *chan,
+					 unsigned int mode)
+{
+	struct mcp356x_state *adc = iio_priv(indio_dev);
+	int ret;
+
+	dev_dbg(&indio_dev->dev, "%s: %d\n", __func__, mode);
+
+	mutex_lock(&adc->lock);
+	ret = mcp356x_update(adc, MCP356X_CONFIG0, MCP356X_CS_SEL_MASK, mode, 1);
+
+	if (ret)
+		dev_err(&indio_dev->dev, "Failed to configure CONFIG0 register\n");
+	else
+		adc->current_bias_mode = mode;
+
+	mutex_unlock(&adc->lock);
+
+	return ret;
+}
+
+static int mcp356x_get_current_bias_mode(struct iio_dev *indio_dev,
+					 const struct iio_chan_spec *chan)
+{
+	struct mcp356x_state *adc = iio_priv(indio_dev);
+
+	return adc->current_bias_mode;
+}
+
+static const struct iio_enum mcp356x_current_boost_mode_enum = {
+	.items = mcp356x_boost_current_avail,
+	.num_items = ARRAY_SIZE(mcp356x_boost_current_avail),
+	.set = mcp356x_set_current_boost_mode,
+	.get = mcp356x_get_current_boost_mode,
+};
+
+static const struct iio_enum mcp356x_current_bias_mode_enum = {
+	.items = mcp356x_current_bias_avail,
+	.num_items = ARRAY_SIZE(mcp356x_current_bias_avail),
+	.set = mcp356x_set_current_bias_mode,
+	.get = mcp356x_get_current_bias_mode,
+};
+
+static const struct iio_chan_spec_ext_info mcp356x_ext_info[] = {
+	IIO_ENUM("boost_current", IIO_SHARED_BY_ALL, &mcp356x_current_boost_mode_enum),
+	{
+		.name = "boost_current_available",
+		.shared = IIO_SHARED_BY_ALL,
+		.read = iio_enum_available_read,
+		.private = (uintptr_t)&mcp356x_current_boost_mode_enum,
+	},
+	IIO_ENUM("current_bias", IIO_SHARED_BY_ALL, &mcp356x_current_bias_mode_enum),
+	{
+		.name = "current_bias_available",
+		.shared = IIO_SHARED_BY_ALL,
+		.read = iio_enum_available_read,
+		.private = (uintptr_t)&mcp356x_current_bias_mode_enum,
+	},
+	{}
+};
+
+static ssize_t mcp356x_auto_zeroing_mux_show(struct device *dev,
+					     struct device_attribute *attr,
+					     char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct mcp356x_state *adc = iio_priv(indio_dev);
+
+	return sysfs_emit(buf, "%d\n", adc->auto_zeroing_mux);
+}
+
+static ssize_t mcp356x_auto_zeroing_mux_store(struct device *dev,
+					      struct device_attribute *attr,
+					      const char *buf, size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct mcp356x_state *adc = iio_priv(indio_dev);
+	bool auto_zero;
+	int ret;
+
+	ret = kstrtobool(buf, &auto_zero);
+	if (ret)
+		return ret;
+
+	mutex_lock(&adc->lock);
+	ret = mcp356x_update(adc, MCP356X_CONFIG2, MCP356X_AZ_MUX_MASK,
+			     (u32)auto_zero, 1);
+
+	if (ret)
+		dev_err(&indio_dev->dev, "Failed to update CONFIG2 register\n");
+	else
+		adc->auto_zeroing_mux = auto_zero;
+
+	mutex_unlock(&adc->lock);
+
+	return ret ? ret : len;
+}
+
+static ssize_t mcp356x_auto_zeroing_ref_show(struct device *dev,
+					     struct device_attribute *attr,
+					     char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct mcp356x_state *adc = iio_priv(indio_dev);
+
+	return sysfs_emit(buf, "%d\n", adc->auto_zeroing_ref);
+}
+
+static ssize_t mcp356x_auto_zeroing_ref_store(struct device *dev,
+					      struct device_attribute *attr,
+					      const char *buf, size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct mcp356x_state *adc = iio_priv(indio_dev);
+	bool auto_zero;
+	int ret;
+
+	ret = kstrtobool(buf, &auto_zero);
+	if (ret)
+		return ret;
+
+	mutex_lock(&adc->lock);
+	ret = mcp356x_update(adc, MCP356X_CONFIG2, MCP356X_AZ_REF_MASK,
+			     (u32)auto_zero, 1);
+
+	if (ret)
+		dev_err(&indio_dev->dev, "Failed to update CONFIG2 register\n");
+	else
+		adc->auto_zeroing_ref = auto_zero;
+
+	mutex_unlock(&adc->lock);
+
+	return ret ? ret : len;
+}
+
+#define MCP356X_DEV_ATTR(name) (&iio_dev_attr_##name.dev_attr.attr)
+
+static IIO_DEVICE_ATTR(enable_auto_zeroing_ref, 0644,
+		       mcp356x_auto_zeroing_ref_show,
+		       mcp356x_auto_zeroing_ref_store, 0);
+
+static struct attribute *mcp356x_particular_attributes[] = {
+	MCP356X_DEV_ATTR(enable_auto_zeroing_ref),
+	NULL
+};
+
+static IIO_DEVICE_ATTR(enable_auto_zeroing_mux, 0644,
+		       mcp356x_auto_zeroing_mux_show,
+		       mcp356x_auto_zeroing_mux_store, 0);
+
+static struct attribute *mcp356x_shared_attributes[] = {
+	MCP356X_DEV_ATTR(enable_auto_zeroing_mux),
+	NULL,
+};
+
+static int mcp356x_prep_custom_attributes(struct mcp356x_state *adc,
+					  struct iio_dev *indio_dev)
+{
+	int i;
+	struct attribute **mcp356x_custom_attr;
+	struct attribute_group *mcp356x_group;
+
+	mcp356x_group = devm_kzalloc(&adc->spi->dev, sizeof(*mcp356x_group), GFP_KERNEL);
+
+	if (!mcp356x_group)
+		return (-ENOMEM);
+
+	mcp356x_custom_attr = devm_kzalloc(&adc->spi->dev, (MCP356X_SHARED_DEVATTRS_COUNT +
+		MCP356X_PARTICULAR_DEVATTRS_COUNT + 1) * sizeof(struct attribute *),
+		GFP_KERNEL);
+
+	if (!mcp356x_custom_attr)
+		return (-ENOMEM);
+
+	for (i = 0; i < MCP356X_SHARED_DEVATTRS_COUNT; i++)
+		mcp356x_custom_attr[i] = mcp356x_shared_attributes[i];
+
+	if (adc->chip_info->has_vref) {
+		dev_dbg(&indio_dev->dev, "Setup custom attr for R variant\n");
+		for (i = 0; i < MCP356X_PARTICULAR_DEVATTRS_COUNT; i++)
+			mcp356x_custom_attr[MCP356X_SHARED_DEVATTRS_COUNT + i] =
+				mcp356x_particular_attributes[i];
+	}
+
+	mcp356x_group->attrs = mcp356x_custom_attr;
+	adc->mcp356x_info.attrs = mcp356x_group;
+
+	return 0;
+}
+
+#define MCP356X_V_CHANNEL(index, addr, depth) {					\
+	.type = IIO_VOLTAGE,							\
+	.indexed = 1,								\
+	.channel = (index),							\
+	.address = (((addr) << 4) | MCP356X_AGND),				\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),				\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),			\
+	.info_mask_shared_by_all  = BIT(IIO_CHAN_INFO_HARDWAREGAIN)	|	\
+				BIT(IIO_CHAN_INFO_CALIBBIAS)		|	\
+				BIT(IIO_CHAN_INFO_CALIBSCALE)		|	\
+				BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),		\
+	.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_CALIBSCALE) |	\
+				BIT(IIO_CHAN_INFO_HARDWAREGAIN)		|	\
+				BIT(IIO_CHAN_INFO_CALIBBIAS)		|	\
+				BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),		\
+	.ext_info = mcp356x_ext_info,						\
+	.scan_index = 0,							\
+	.scan_type = {								\
+		.sign = 's',							\
+		.realbits = depth,						\
+		.storagebits = 32,						\
+		.endianness = IIO_BE,						\
+	},									\
+}
+
+#define MCP356X_T_CHAN(depth) {							\
+	.type = IIO_TEMP,							\
+	.channel = 0,								\
+	.address = ((MCP356X_TEMP_DIODE_P << 4) | MCP356X_TEMP_DIODE_M),	\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),				\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),			\
+	.info_mask_shared_by_all  = BIT(IIO_CHAN_INFO_HARDWAREGAIN)	|	\
+			BIT(IIO_CHAN_INFO_CALIBBIAS)			|	\
+			BIT(IIO_CHAN_INFO_CALIBSCALE)			|	\
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),			\
+	.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_CALIBSCALE) |	\
+			BIT(IIO_CHAN_INFO_CALIBBIAS)			|	\
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),			\
+	.ext_info = mcp356x_ext_info,						\
+	.scan_index = 0,							\
+	.scan_type = {								\
+		.sign = 'u',							\
+		.realbits = depth,						\
+		.storagebits = 32,						\
+		.endianness = IIO_BE,						\
+	},									\
+}
+
+#define MCP356X_V_CHANNEL_DIFF(chan1, chan2, addr, depth) {			\
+	.type = IIO_VOLTAGE,							\
+	.indexed = 1,								\
+	.channel = (chan1),							\
+	.channel2 = (chan2),							\
+	.address = (addr),							\
+	.differential = 1,							\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),				\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),			\
+	.info_mask_shared_by_all  = BIT(IIO_CHAN_INFO_HARDWAREGAIN)	|	\
+			BIT(IIO_CHAN_INFO_CALIBBIAS)			|	\
+			BIT(IIO_CHAN_INFO_CALIBSCALE)			|	\
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),			\
+	.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_CALIBSCALE) |	\
+			BIT(IIO_CHAN_INFO_CALIBBIAS)			|	\
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),			\
+	.ext_info = mcp356x_ext_info,						\
+	.scan_index = 0,							\
+	.scan_type = {								\
+		.sign = 's',							\
+		.realbits = depth,						 \
+		.storagebits = 32,						\
+		.endianness = IIO_BE,						\
+	},									\
+}
+
+#define MCP3561_CHANNELS(depth) {			\
+	MCP356X_V_CHANNEL(0, 0, depth),			\
+	MCP356X_V_CHANNEL(1, 1, depth),			\
+	MCP356X_V_CHANNEL_DIFF(0, 1, 0x01, depth),	\
+	MCP356X_V_CHANNEL_DIFF(1, 0, 0x10, depth),	\
+	MCP356X_T_CHAN(depth)				\
+}
+
+#define MCP3562_CHANNELS(depth) {			\
+	MCP356X_V_CHANNEL(0, 0, depth),			\
+	MCP356X_V_CHANNEL(1, 1, depth),			\
+	MCP356X_V_CHANNEL(2, 2, depth),			\
+	MCP356X_V_CHANNEL(3, 3, depth),			\
+	MCP356X_T_CHAN(depth),				\
+	MCP356X_V_CHANNEL_DIFF(0, 1, 0x01, depth),	\
+	MCP356X_V_CHANNEL_DIFF(1, 0, 0x10, depth),	\
+	MCP356X_V_CHANNEL_DIFF(0, 2, 0x02, depth),	\
+	MCP356X_V_CHANNEL_DIFF(0, 3, 0x03, depth),	\
+	MCP356X_V_CHANNEL_DIFF(1, 2, 0x12, depth),	\
+	MCP356X_V_CHANNEL_DIFF(1, 3, 0x13, depth),	\
+	MCP356X_V_CHANNEL_DIFF(2, 3, 0x23, depth),	\
+	MCP356X_V_CHANNEL_DIFF(2, 0, 0x20, depth),	\
+	MCP356X_V_CHANNEL_DIFF(3, 0, 0x30, depth),	\
+	MCP356X_V_CHANNEL_DIFF(2, 1, 0x21, depth),	\
+	MCP356X_V_CHANNEL_DIFF(3, 1, 0x31, depth),	\
+	MCP356X_V_CHANNEL_DIFF(3, 2, 0x32, depth),	\
+}
+
+#define MCP3564_CHANNELS(depth) {			\
+	MCP356X_V_CHANNEL(0, 0, depth),			\
+	MCP356X_V_CHANNEL(1, 1, depth),			\
+	MCP356X_V_CHANNEL(2, 2, depth),			\
+	MCP356X_V_CHANNEL(3, 3, depth),			\
+	MCP356X_V_CHANNEL(4, 4, depth),			\
+	MCP356X_V_CHANNEL(5, 5, depth),			\
+	MCP356X_V_CHANNEL(6, 6, depth),			\
+	MCP356X_V_CHANNEL(7, 7, depth),			\
+	MCP356X_T_CHAN(depth),				\
+	MCP356X_V_CHANNEL_DIFF(0, 1, 0x01, depth),	\
+	MCP356X_V_CHANNEL_DIFF(1, 0, 0x10, depth),	\
+	MCP356X_V_CHANNEL_DIFF(0, 2, 0x02, depth),	\
+	MCP356X_V_CHANNEL_DIFF(0, 3, 0x03, depth),	\
+	MCP356X_V_CHANNEL_DIFF(1, 2, 0x12, depth),	\
+	MCP356X_V_CHANNEL_DIFF(1, 3, 0x13, depth),	\
+	MCP356X_V_CHANNEL_DIFF(2, 3, 0x23, depth),	\
+	MCP356X_V_CHANNEL_DIFF(2, 0, 0x20, depth),	\
+	MCP356X_V_CHANNEL_DIFF(3, 0, 0x30, depth),	\
+	MCP356X_V_CHANNEL_DIFF(2, 1, 0x21, depth),	\
+	MCP356X_V_CHANNEL_DIFF(3, 1, 0x31, depth),	\
+	MCP356X_V_CHANNEL_DIFF(3, 2, 0x32, depth),	\
+	MCP356X_V_CHANNEL_DIFF(0, 4, 0x04, depth),	\
+	MCP356X_V_CHANNEL_DIFF(0, 5, 0x05, depth),	\
+	MCP356X_V_CHANNEL_DIFF(0, 6, 0x06, depth),	\
+	MCP356X_V_CHANNEL_DIFF(0, 7, 0x07, depth),	\
+	MCP356X_V_CHANNEL_DIFF(1, 4, 0x14, depth),	\
+	MCP356X_V_CHANNEL_DIFF(1, 5, 0x15, depth),	\
+	MCP356X_V_CHANNEL_DIFF(1, 6, 0x16, depth),	\
+	MCP356X_V_CHANNEL_DIFF(1, 7, 0x17, depth),	\
+	MCP356X_V_CHANNEL_DIFF(2, 4, 0x24, depth),	\
+	MCP356X_V_CHANNEL_DIFF(2, 5, 0x25, depth),	\
+	MCP356X_V_CHANNEL_DIFF(2, 6, 0x26, depth),	\
+	MCP356X_V_CHANNEL_DIFF(2, 7, 0x27, depth),	\
+	MCP356X_V_CHANNEL_DIFF(3, 4, 0x34, depth),	\
+	MCP356X_V_CHANNEL_DIFF(3, 5, 0x35, depth),	\
+	MCP356X_V_CHANNEL_DIFF(3, 6, 0x36, depth),	\
+	MCP356X_V_CHANNEL_DIFF(3, 7, 0x37, depth),	\
+	MCP356X_V_CHANNEL_DIFF(4, 5, 0x45, depth),	\
+	MCP356X_V_CHANNEL_DIFF(4, 6, 0x46, depth),	\
+	MCP356X_V_CHANNEL_DIFF(4, 7, 0x47, depth),	\
+	MCP356X_V_CHANNEL_DIFF(5, 6, 0x56, depth),	\
+	MCP356X_V_CHANNEL_DIFF(5, 7, 0x57, depth),	\
+	MCP356X_V_CHANNEL_DIFF(6, 7, 0x67, depth),	\
+	MCP356X_V_CHANNEL_DIFF(4, 0, 0x40, depth),	\
+	MCP356X_V_CHANNEL_DIFF(5, 0, 0x50, depth),	\
+	MCP356X_V_CHANNEL_DIFF(6, 0, 0x60, depth),	\
+	MCP356X_V_CHANNEL_DIFF(7, 0, 0x70, depth),	\
+	MCP356X_V_CHANNEL_DIFF(4, 1, 0x41, depth),	\
+	MCP356X_V_CHANNEL_DIFF(5, 1, 0x51, depth),	\
+	MCP356X_V_CHANNEL_DIFF(6, 1, 0x61, depth),	\
+	MCP356X_V_CHANNEL_DIFF(7, 1, 0x71, depth),	\
+	MCP356X_V_CHANNEL_DIFF(4, 2, 0x42, depth),	\
+	MCP356X_V_CHANNEL_DIFF(5, 2, 0x52, depth),	\
+	MCP356X_V_CHANNEL_DIFF(6, 2, 0x62, depth),	\
+	MCP356X_V_CHANNEL_DIFF(7, 2, 0x72, depth),	\
+	MCP356X_V_CHANNEL_DIFF(4, 3, 0x43, depth),	\
+	MCP356X_V_CHANNEL_DIFF(5, 3, 0x53, depth),	\
+	MCP356X_V_CHANNEL_DIFF(6, 3, 0x63, depth),	\
+	MCP356X_V_CHANNEL_DIFF(7, 3, 0x73, depth),	\
+	MCP356X_V_CHANNEL_DIFF(5, 4, 0x54, depth),	\
+	MCP356X_V_CHANNEL_DIFF(6, 4, 0x64, depth),	\
+	MCP356X_V_CHANNEL_DIFF(7, 4, 0x74, depth),	\
+	MCP356X_V_CHANNEL_DIFF(6, 5, 0x65, depth),	\
+	MCP356X_V_CHANNEL_DIFF(7, 5, 0x75, depth),	\
+	MCP356X_V_CHANNEL_DIFF(7, 6, 0x76, depth)	\
+}
+
+static const struct iio_chan_spec mcp3461_channels[] = MCP3561_CHANNELS(16);
+static const struct iio_chan_spec mcp3462_channels[] = MCP3562_CHANNELS(16);
+static const struct iio_chan_spec mcp3464_channels[] = MCP3564_CHANNELS(16);
+static const struct iio_chan_spec mcp3561_channels[] = MCP3561_CHANNELS(24);
+static const struct iio_chan_spec mcp3562_channels[] = MCP3562_CHANNELS(24);
+static const struct iio_chan_spec mcp3564_channels[] = MCP3564_CHANNELS(24);
+
+static const struct mcp356x_chip_info mcp356x_chip_infos_tbl[] = {
+	[mcp3461] = {
+		.channels = mcp3461_channels,
+		.num_channels = ARRAY_SIZE(mcp3461_channels),
+		.int_vref_uv = 0,
+		.has_vref = false
+	},
+	[mcp3462] = {
+		.channels = mcp3462_channels,
+		.num_channels = ARRAY_SIZE(mcp3462_channels),
+		.int_vref_uv = 0,
+		.has_vref = false
+	},
+	[mcp3464] = {
+		.channels = mcp3464_channels,
+		.num_channels = ARRAY_SIZE(mcp3464_channels),
+		.int_vref_uv = 0,
+		.has_vref = false
+	},
+	[mcp3461r] = {
+		.channels = mcp3461_channels,
+		.num_channels = ARRAY_SIZE(mcp3461_channels),
+		.int_vref_uv = MCP356XR_INT_VREF_MV,
+		.has_vref = true
+	},
+	[mcp3462r] = {
+		.channels = mcp3462_channels,
+		.num_channels = ARRAY_SIZE(mcp3462_channels),
+		.int_vref_uv = MCP356XR_INT_VREF_MV,
+		.has_vref = true
+	},
+	[mcp3464r] = {
+		.channels = mcp3464_channels,
+		.num_channels = ARRAY_SIZE(mcp3464_channels),
+		.int_vref_uv = MCP356XR_INT_VREF_MV,
+		.has_vref = true
+	},
+	[mcp3561] = {
+		.channels = mcp3561_channels,
+		.num_channels = ARRAY_SIZE(mcp3561_channels),
+		.int_vref_uv = 0,
+		.has_vref = false
+	},
+	[mcp3562] = {
+		.channels = mcp3562_channels,
+		.num_channels = ARRAY_SIZE(mcp3562_channels),
+		.int_vref_uv = 0,
+		.has_vref = false
+	},
+	[mcp3564] = {
+		.channels = mcp3564_channels,
+		.num_channels = ARRAY_SIZE(mcp3564_channels),
+		.int_vref_uv = 0,
+		.has_vref = false
+	},
+	[mcp3561r] = {
+		.channels = mcp3561_channels,
+		.num_channels = ARRAY_SIZE(mcp3561_channels),
+		.int_vref_uv = MCP356XR_INT_VREF_MV,
+		.has_vref = true
+	},
+	[mcp3562r] = {
+		.channels = mcp3562_channels,
+		.num_channels = ARRAY_SIZE(mcp3562_channels),
+		.int_vref_uv = MCP356XR_INT_VREF_MV,
+		.has_vref = true
+	},
+	[mcp3564r] = {
+		.channels = mcp3564_channels,
+		.num_channels = ARRAY_SIZE(mcp3564_channels),
+		.int_vref_uv = MCP356XR_INT_VREF_MV,
+		.has_vref = true
+	},
+};
+
+static int mcp356x_read_single_value(struct iio_dev *indio_dev,
+				     struct iio_chan_spec const *channel,
+				     int *val)
+{
+	struct mcp356x_state *adc = iio_priv(indio_dev);
+	int ret, tmp, ret_read = 0;
+
+	/* Configure MUX register with the requested channel */
+	ret = mcp356x_write(adc, MCP356X_MUX, channel->address, 1);
+	if (ret) {
+		dev_err(&indio_dev->dev, "Failed to configure MUX register\n");
+		return ret;
+	}
+
+	/* ADC Conversion starts by writing ADC_MODE[1:0] = 11 to CONFIG0[1:0] =  */
+	ret = mcp356x_update(adc, MCP356X_CONFIG0, MCP356X_ADC_MODE_MASK,
+			     MCP356X_ADC_CONVERSION_MODE, 1);
+	if (ret) {
+		dev_err(&indio_dev->dev,
+			"Failed to configure CONFIG0 register\n");
+		return ret;
+	}
+
+	/*
+	 * Check if the conversion is ready. If not, wait a little bit, and
+	 * in case of timeout exit with an error.
+	 */
+
+	ret = read_poll_timeout(mcp356x_read, ret_read,
+				ret_read || !(tmp & MCP356X_DATA_READY_MASK),
+				1000, MCP356X_DATA_READY_TIMEOUT_MS * 1000, true,
+				adc, MCP356X_IRQ, &tmp, 1);
+
+	/* failed to read status register */
+	if (ret_read)
+		return ret;
+
+	if (ret)
+		return -ETIMEDOUT;
+
+	if (tmp & MCP356X_DATA_READY_MASK)
+		/* failing to finish conversion */
+		return -EBUSY;
+
+	ret = mcp356x_read(adc, MCP356X_ADCDATA, &tmp, 4);
+	if (ret)
+		return ret;
+
+	*val = tmp;
+
+	return ret;
+}
+
+static int mcp356x_read_avail(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *channel,
+			      const int **vals, int *type,
+			      int *length, long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*type = IIO_VAL_INT;
+		*vals = mcp356x_oversampling_avail;
+		*length = ARRAY_SIZE(mcp356x_oversampling_avail);
+		return IIO_AVAIL_LIST;
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		*type = IIO_VAL_FRACTIONAL;
+		*length = ARRAY_SIZE(mcp356x_hwgain_frac);
+		*vals = mcp356x_hwgain_frac;
+		return IIO_AVAIL_LIST;
+	case IIO_CHAN_INFO_CALIBBIAS:
+		*vals = mcp356x_calib_bias;
+		*type = IIO_VAL_INT;
+		return IIO_AVAIL_RANGE;
+	case IIO_CHAN_INFO_CALIBSCALE:
+		*vals = mcp356x_calib_scale;
+		*type = IIO_VAL_INT;
+		return IIO_AVAIL_RANGE;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int mcp356x_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *channel,
+			    int *val, int *val2, long mask)
+{
+	struct mcp356x_state *adc = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&adc->lock);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = mcp356x_read_single_value(indio_dev, channel, val);
+		if (ret)
+			ret = -EINVAL;
+		else
+			ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_SCALE:
+		*val = adc->vref_mv;
+		*val2 = channel->scan_type.realbits - 1;
+		ret = IIO_VAL_FRACTIONAL_LOG2;
+		break;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*val = mcp356x_oversampling_avail[adc->oversampling];
+		ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		*val = mcp356x_hwgain_frac[2 * adc->hwgain];
+		*val2 = mcp356x_hwgain_frac[(2 * adc->hwgain) + 1];
+		ret = IIO_VAL_FRACTIONAL;
+		break;
+	case IIO_CHAN_INFO_CALIBBIAS:
+		*val = adc->calib_bias;
+		ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_CALIBSCALE:
+		*val = adc->calib_scale;
+		ret = IIO_VAL_INT;
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	mutex_unlock(&adc->lock);
+
+	return ret;
+}
+
+static int mcp356x_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *channel, int val,
+			     int val2, long mask)
+{
+	struct mcp356x_state *adc = iio_priv(indio_dev);
+	int tmp;
+	int ret = -EINVAL;
+
+	mutex_lock(&adc->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_CALIBBIAS:
+		if (val < mcp356x_calib_bias[0] && val > mcp356x_calib_bias[2])
+			goto out;
+
+		adc->calib_bias = val;
+		ret = mcp356x_write(adc, MCP356X_OFFSETCAL, val, 3);
+		break;
+	case IIO_CHAN_INFO_CALIBSCALE:
+		if (val < mcp356x_calib_bias[0] && val > mcp356x_calib_bias[2])
+			goto out;
+
+		adc->calib_scale = val;
+		ret = mcp356x_write(adc, MCP356X_GAINCAL, val, 3);
+		break;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		if (val < 0)
+			goto out;
+
+		adc->oversampling = find_closest(val, mcp356x_oversampling_avail,
+						 ARRAY_SIZE(mcp356x_oversampling_avail));
+
+		dev_dbg(&adc->spi->dev,
+			"IIO_CHAN_INFO_OVERSAMPLING_RATIO index %d\n",
+			adc->oversampling);
+
+		ret = mcp356x_update(adc, MCP356X_CONFIG1, MCP356X_OVERSAMPLING_RATIO_MASK,
+				     (adc->oversampling << MCP356X_OVERSAMPLING_RATIO_SHIFT),
+				     1);
+		if (ret)
+			dev_err(&indio_dev->dev,
+				"Failed to configure CONFIG1 register\n");
+
+		break;
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		/*
+		 * calculate gain from read values.
+		 * avoid using fractional numbers so
+		 * multiply the value with 1000. In case of x1/3 gain
+		 * the tmp will be 300
+		 */
+		tmp = ((val * 1000000) + val2) / 1000;
+		if (tmp < 1 || tmp > MAX_HWGAIN)
+			goto out;
+
+		adc->hwgain = find_closest(tmp, mcp356x_hwgain,
+					   ARRAY_SIZE(mcp356x_hwgain));
+
+		dev_dbg(&adc->spi->dev,
+			"IIO_CHAN_INFO_HARDWAREGAIN Gain:%d; index %d\n",
+			tmp, adc->hwgain);
+
+		/* Update GAIN in CONFIG2[5:3] -> GAIN[2:0]*/
+		ret = mcp356x_update(adc, MCP356X_CONFIG2, MCP356X_HARDWARE_GAIN_MASK,
+				     (adc->hwgain << MCP356X_HARDWARE_GAIN_SHIFT), 1);
+		if (ret)
+			dev_err(&indio_dev->dev,
+				"Failed to configure CONFIG0 register\n");
+		break;
+	}
+
+out:
+	mutex_unlock(&adc->lock);
+
+	return ret;
+}
+
+static int mcp356x_config(struct mcp356x_state *adc)
+{
+	int ret = 0;
+	unsigned int tmp;
+
+	dev_dbg(&adc->spi->dev, "%s: Start config...\n", __func__);
+
+	/*
+	 * The address is set on a per-device basis by fuses in the factory,
+	 * configured on request. If not requested, the fuses are set for 0x1.
+	 * The device address is part of the device markings to avoid
+	 * potential confusion. This address is coded on two bits, so four possible
+	 * addresses are available when multiple devices are present on the same
+	 * SPI bus with only one Chip Select line for all devices.
+	 */
+	device_property_read_u32(&adc->spi->dev, "microchip,hw-device-address", &tmp);
+
+	if (tmp > 3) {
+		dev_err_probe(&adc->spi->dev, tmp,
+			      "invalid device address. Must be in range 0-3.\n");
+		return -EINVAL;
+	}
+
+	adc->dev_addr = 0xff & tmp;
+
+	dev_dbg(&adc->spi->dev, "use device address %i\n", adc->dev_addr);
+
+	ret = mcp356x_read(adc, MCP356X_RESERVED_E, &tmp, 2);
+
+	if (ret == 0) {
+		switch (tmp & MCP356X_HW_ID_MASK) {
+		case MCP3461_HW_ID:
+			dev_dbg(&adc->spi->dev, "Found MCP3461 chip\n");
+			break;
+		case MCP3462_HW_ID:
+			dev_dbg(&adc->spi->dev, "Found MCP3462 chip\n");
+			break;
+		case MCP3464_HW_ID:
+			dev_dbg(&adc->spi->dev, "Found MCP3464 chip\n");
+			break;
+		case MCP3561_HW_ID:
+			dev_dbg(&adc->spi->dev, "Found MCP3561 chip\n");
+			break;
+		case MCP3562_HW_ID:
+			dev_dbg(&adc->spi->dev, "Found MCP3562 chip\n");
+			break;
+		case MCP3564_HW_ID:
+			dev_dbg(&adc->spi->dev, "Found MCP3564 chip\n");
+			break;
+		default:
+			dev_err_probe(&adc->spi->dev, tmp,
+				      "Unknown chip found\n");
+			return -EINVAL;
+		}
+	} else {
+		return ret;
+	}
+
+	/* Command sequence that ensures a recovery with
+	 * the desired settings in any cases of loss-of-power scenario.
+	 */
+
+	/* Write LOCK register to 0xA5 (Write Access Password)
+	 * Write access is allowed on the full register map.
+	 */
+	ret = mcp356x_write(adc, MCP356X_LOCK, 0x000000A5, 1);
+	if (ret)
+		return ret;
+
+	/* Write IRQ register to 0x03 */
+	/* IRQ --> IRQ Mode = Hi-Z IRQ Output  --> (0b00000011).
+	 * IRQ = 0x00000003
+	 */
+	ret = mcp356x_write(adc, MCP356X_IRQ, 0x00000003, 1);
+	if (ret)
+		return ret;
+
+	/* Device Full Reset Fast Command */
+	ret = mcp356x_fast_cmd(adc, MCP356X_FULL_RESET_CMD);
+
+	/* wait 1ms for the chip to restart after a full reset */
+	mdelay(1);
+
+	/* Reconfigure the ADC chip  */
+
+	/* GAINCAL --> Disabled.
+	 * Default value is GAINCAL = 0x00800000; which provides a gain of 1x
+	 */
+	ret = mcp356x_write(adc, MCP356X_GAINCAL, 0x00800000, 3);
+	if (ret)
+		return ret;
+
+	adc->calib_scale = 0x00800000;
+
+	/* OFFSETCAL --> 0 Counts of Offset Cancellation
+	 * (Measured offset is negative).
+	 * OFFSETCAL = 0x0
+	 */
+	ret = mcp356x_write(adc, MCP356X_OFFSETCAL, 0x00000000, 3);
+	if (ret)
+		return ret;
+
+	/* TIMER --> Disabled.
+	 * TIMER = 0x00000000
+	 */
+	ret = mcp356x_write(adc, MCP356X_TIMER, 0x00000000, 3);
+	if (ret)
+		return ret;
+
+	/* SCAN --> Disabled.
+	 * SCAN = 0x00000000
+	 */
+	ret = mcp356x_write(adc, MCP356X_SCAN, 0x00000000, 3);
+	if (ret)
+		return ret;
+
+	/* MUX --> VIN+ = CH0, VIN- = CH1 --> (0b00000001).
+	 * MUX = 0x00000001
+	 */
+	ret = mcp356x_write(adc, MCP356X_MUX, 0x00000001, 1);
+	if (ret)
+		return ret;
+
+	/* IRQ --> IRQ Mode = Hi-Z IRQ Output  --> (0b00000011).
+	 * IRQ = 0x00000003
+	 */
+	ret = mcp356x_write(adc, MCP356X_IRQ, 0x00000003, 1);
+	if (ret)
+		return ret;
+
+	/* CONFIG3
+	 * Conv. Mod = One-Shot/Standby,
+	 * FORMAT = 32-bit (right justified data): SGN extension + ADC data,
+	 * CRC_FORMAT = 16b, CRC-COM = Disabled,
+	 * OFFSETCAL = Enabled, GAINCAL = Enabled --> (10100011).
+	 * CONFIG3 = 0x000000A3
+	 *
+	 */
+	ret = mcp356x_write(adc, MCP356X_CONFIG3, 0x000000A3, 1);
+	if (ret)
+		return ret;
+
+	/* CONFIG2 --> BOOST = 1x, GAIN = 1x, AZ_MUX = 1 --> (0b10001101).
+	 * CONFIG2 = 0x0000008D
+	 */
+	ret = mcp356x_write(adc, MCP356X_CONFIG2, 0x0000008D, 1);
+	if (ret)
+		return ret;
+
+	adc->hwgain = 0x01;
+	adc->auto_zeroing_mux = true;
+	adc->auto_zeroing_ref = false;
+	adc->current_boost_mode = MCP356X_BOOST_CURRENT_x1_00;
+
+	/* CONFIG1 --> AMCLK = MCLK, OSR = 98304 --> (0b00111100).
+	 * CONFIG1 = 0x0000003C
+	 */
+	ret = mcp356x_write(adc, MCP356X_CONFIG1, 0x0000003C, 1);
+	if (ret)
+		return ret;
+
+	adc->oversampling = 0x0F;
+
+	if (!adc->vref) {
+		/* CONFIG0 --> VREF_SEL = Internal Voltage Reference 2.4v
+		 * CLK_SEL = INTOSC w/o CLKOUT, CS_SEL = No Bias,
+		 * ADC_MODE = Standby Mode --> (0b11100010).
+		 * CONFIG0 = 0x000000E2
+		 */
+		ret = mcp356x_write(adc, MCP356X_CONFIG0, 0x000000E2, 1);
+
+		dev_dbg(&adc->spi->dev, "%s: Using internal Vref\n",
+			__func__);
+		adc->vref_mv = MCP356XR_INT_VREF_MV;
+
+	} else {
+		/* CONFIG0 --> CLK_SEL = INTOSC w/o CLKOUT, CS_SEL = No Bias,
+		 * ADC_MODE = Standby Mode --> (0b01100010).
+		 * CONFIG0 = 0x000000E2
+		 */
+		ret = mcp356x_write(adc, MCP356X_CONFIG0, 0x00000062, 1);
+	}
+	adc->current_bias_mode = MCP356X_CS_SEL_0_0_uA;
+
+	return ret;
+}
+
+static int mcp356x_probe(struct spi_device *spi)
+{
+	int ret, device_index;
+	struct iio_dev *indio_dev;
+	struct mcp356x_state *adc;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
+	if (!indio_dev) {
+		dev_err_probe(&indio_dev->dev, PTR_ERR(indio_dev),
+			      "Can't allocate iio device\n");
+		return -ENOMEM;
+	}
+
+	adc = iio_priv(indio_dev);
+	adc->spi = spi;
+
+	dev_dbg(&adc->spi->dev, "%s: probe(spi = 0x%p)\n", __func__, spi);
+
+	adc->vref = devm_regulator_get_optional(&adc->spi->dev, "vref");
+	if (IS_ERR(adc->vref)) {
+		if (PTR_ERR(adc->vref) == -ENODEV) {
+			adc->vref = NULL;
+			dev_dbg(&adc->spi->dev, "%s: Using internal Vref\n",
+				__func__);
+		} else {
+			dev_err_probe(&adc->spi->dev, PTR_ERR(adc->vref),
+				      "failed to get regulator\n");
+			return PTR_ERR(adc->vref);
+		}
+	} else {
+		ret = regulator_enable(adc->vref);
+		if (ret)
+			return ret;
+
+		dev_dbg(&adc->spi->dev, "%s: Using External Vref\n",
+			__func__);
+
+		ret = regulator_get_voltage(adc->vref);
+		if (ret < 0) {
+			dev_err_probe(&adc->spi->dev, ret,
+				      "Failed to read vref regulator\n");
+			goto error_disable_reg;
+		}
+
+		adc->vref_mv = ret / 1000;
+	}
+
+	spi_set_drvdata(spi, indio_dev);
+	device_index = spi_get_device_id(spi)->driver_data;
+	adc->chip_info = &mcp356x_chip_infos_tbl[device_index];
+
+	adc->mcp356x_info.read_raw = mcp356x_read_raw;
+	adc->mcp356x_info.write_raw = mcp356x_write_raw;
+	adc->mcp356x_info.read_avail = mcp356x_read_avail;
+
+	ret = mcp356x_prep_custom_attributes(adc, indio_dev);
+	if (ret) {
+		dev_err_probe(&adc->spi->dev, ret,
+			      "Can't configure custom attributes for MCP356X device\n");
+		goto error_disable_reg;
+	}
+
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &adc->mcp356x_info;
+
+	indio_dev->channels = adc->chip_info->channels;
+	indio_dev->num_channels = adc->chip_info->num_channels;
+	indio_dev->masklength = adc->chip_info->num_channels - 1;
+
+	/* initialize the chip access mutex */
+	mutex_init(&adc->lock);
+
+	/* Do any chip specific initialization, e.g:
+	 * read/write some registers
+	 * enable/disable certain channels
+	 * change the sampling rate to the requested value
+	 */
+	ret = mcp356x_config(adc);
+	if (ret) {
+		dev_err_probe(&adc->spi->dev, ret,
+			      "Can't configure MCP356X device\n");
+		goto error_disable_reg;
+	}
+
+	dev_dbg(&adc->spi->dev, "%s: Vref (mV): %d\n", __func__, adc->vref_mv);
+
+	ret = devm_iio_device_register(&spi->dev, indio_dev);
+	if (ret) {
+		dev_err_probe(&adc->spi->dev, ret,
+			      "Can't register IIO device\n");
+		goto error_disable_reg;
+	}
+
+	return 0;
+
+error_disable_reg:
+	if (adc->vref)
+		regulator_disable(adc->vref);
+
+	return ret;
+}
+
+static void mcp356x_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct mcp356x_state *adc = iio_priv(indio_dev);
+
+	if (adc->vref)
+		regulator_disable(adc->vref);
+}
+
+static const struct of_device_id mcp356x_dt_ids[] = {
+	{ .compatible = "microchip,mcp3461" },
+	{ .compatible = "microchip,mcp3462" },
+	{ .compatible = "microchip,mcp3464" },
+	{ .compatible = "microchip,mcp3461r" },
+	{ .compatible = "microchip,mcp3462r" },
+	{ .compatible = "microchip,mcp3464r" },
+	{ .compatible = "microchip,mcp3561" },
+	{ .compatible = "microchip,mcp3562" },
+	{ .compatible = "microchip,mcp3564" },
+	{ .compatible = "microchip,mcp3561r" },
+	{ .compatible = "microchip,mcp3562r" },
+	{ .compatible = "microchip,mcp3564r" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mcp356x_dt_ids);
+
+static const struct spi_device_id mcp356x_id[] = {
+	{ "mcp3461",  mcp3461 },
+	{ "mcp3462",  mcp3462 },
+	{ "mcp3464",  mcp3464 },
+	{ "mcp3461r", mcp3461r },
+	{ "mcp3462r", mcp3462r },
+	{ "mcp3464r", mcp3464r },
+	{ "mcp3561",  mcp3561 },
+	{ "mcp3562",  mcp3562 },
+	{ "mcp3564",  mcp3564 },
+	{ "mcp3561r", mcp3561r },
+	{ "mcp3562r", mcp3562r },
+	{ "mcp3564r", mcp3564r },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, mcp356x_id);
+
+static struct spi_driver mcp356x_driver = {
+	.driver = {
+		.name = "mcp3564",
+		.of_match_table = mcp356x_dt_ids,
+	},
+	.probe = mcp356x_probe,
+	.remove = mcp356x_remove,
+	.id_table = mcp356x_id,
+};
+
+module_spi_driver(mcp356x_driver);
+
+MODULE_AUTHOR("Marius Cristea <marius.cristea@microchip.com>");
+MODULE_DESCRIPTION("Microchip MCP346x/MCP346xR and MCP356x/MCP346xR ADCs");
+MODULE_LICENSE("GPL v2");
+MODULE_VERSION("0.1.2");
-- 
2.39.2