From 37b0b79827edbd5c312aa546a1fe148bda616e30 Mon Sep 17 00:00:00 2001
From: Sam Shih <sam.shih@mediatek.com>
Date: Wed, 31 May 2023 19:53:09 +0800
Subject: [PATCH] iio: adc: Add rtq6056 support

---
 drivers/iio/adc/Kconfig   |  15 +
 drivers/iio/adc/Makefile  |   1 +
 drivers/iio/adc/rtq6056.c | 649 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 665 insertions(+)
 create mode 100644 drivers/iio/adc/rtq6056.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index cb57880..7457a53 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -746,6 +746,21 @@ config ROCKCHIP_SARADC
 	  To compile this driver as a module, choose M here: the
 	  module will be called rockchip_saradc.
 
+config RICHTEK_RTQ6056
+	tristate "Richtek RTQ6056 Current and Power Monitor ADC"
+	depends on I2C
+	select REGMAP_I2C
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to enable RQT6056 ADC support.
+	  RTQ6056 is a high accuracy current-sense monitor with I2C and SMBus
+	  compatible interface, and the device provides full information for
+	  system by reading out the load current and power.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called rtq6056.
+
 config SC27XX_ADC
 	tristate "Spreadtrum SC27xx series PMICs ADC"
 	depends on MFD_SC27XX_PMIC || COMPILE_TEST
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index ef9cc48..6a4ac1b 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -59,6 +59,7 @@ 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
+obj-$(CONFIG_RICHTEK_RTQ6056) += rtq6056.o
 obj-$(CONFIG_MXS_LRADC_ADC) += mxs-lradc-adc.o
 obj-$(CONFIG_NAU7802) += nau7802.o
 obj-$(CONFIG_NPCM_ADC) += npcm_adc.o
diff --git a/drivers/iio/adc/rtq6056.c b/drivers/iio/adc/rtq6056.c
new file mode 100644
index 0000000..962058e
--- /dev/null
+++ b/drivers/iio/adc/rtq6056.c
@@ -0,0 +1,649 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2022 Richtek Technology Corp.
+ *
+ * ChiYuan Huang <cy_huang@richtek.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/sysfs.h>
+#include <linux/types.h>
+#include <linux/util_macros.h>
+
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/driver.h>
+#include <linux/iio/machine.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+#define RTQ6056_REG_CONFIG	0x00
+#define RTQ6056_REG_SHUNTVOLT	0x01
+#define RTQ6056_REG_BUSVOLT	0x02
+#define RTQ6056_REG_POWER	0x03
+#define RTQ6056_REG_CURRENT	0x04
+#define RTQ6056_REG_CALIBRATION	0x05
+#define RTQ6056_REG_MASKENABLE	0x06
+#define RTQ6056_REG_ALERTLIMIT	0x07
+#define RTQ6056_REG_MANUFACTID	0xFE
+#define RTQ6056_REG_DIEID	0xFF
+
+#define RTQ6056_MAX_CHANNEL	4
+#define RTQ6056_VENDOR_ID	0x1214
+#define RTQ6056_DEFAULT_CONFIG	0x4127
+#define RTQ6056_CONT_ALLON	7
+
+#define RTQ6056_CONFIG_OPMODE_MASK	GENMASK(2, 0)
+#define RTQ6056_CONFIG_OPMODE(x)	((x << 0) & RTQ6056_CONFIG_OPMODE_MASK)
+#define RTQ6056_CONFIG_VSHUNTCT_MASK	GENMASK(5, 3)
+#define RTQ6056_CONFIG_VSHUNTCT(x)	((x << 3) & \
+					 RTQ6056_CONFIG_VSHUNTCT_MASK)
+#define RTQ6056_CONFIG_VBUSCT_MASK	GENMASK(8, 6)
+#define RTQ6056_CONFIG_VBUSCT(x)	((x << 6) & RTQ6056_CONFIG_VBUSCT_MASK)
+#define RTQ6056_CONFIG_AVG_MASK		GENMASK(11, 9)
+#define RTQ6056_CONFIG_AVG(x)		((x << 9) & RTQ6056_CONFIG_AVG_MASK)
+#define RTQ6056_CONFIG_RESET_MASK	GENMASK(15, 15)
+#define RTQ6056_CONFIG_RESET(x)		((x << 15) & RTQ6056_CONFIG_RESET_MASK)
+
+struct rtq6056_priv {
+	struct device *dev;
+	struct regmap *regmap;
+	u32 shunt_resistor_uohm;
+	int vshuntct_us;
+	int vbusct_us;
+	int avg_sample;
+};
+
+static struct iio_map rtq6056_maps[] = {
+	{
+		.consumer_dev_name = "voltage0",
+		.consumer_channel = "voltage0",
+		.adc_channel_label = "Vshunt",
+	}, {
+		.consumer_dev_name = "voltage1",
+		.consumer_channel = "voltage1",
+		.adc_channel_label = "Vbus",
+	}, {
+		.consumer_dev_name = "power2",
+		.consumer_channel = "power2",
+		.adc_channel_label = "Power",
+	}, {
+		.consumer_dev_name = "current3",
+		.consumer_channel = "current3",
+		.adc_channel_label = "Current",
+	}, { /* sentinel */ }
+};
+
+static const struct iio_chan_spec rtq6056_channels[RTQ6056_MAX_CHANNEL + 1] = {
+	{
+		.type = IIO_VOLTAGE,
+		.indexed = 1,
+		.channel = 0,
+		.address = RTQ6056_REG_SHUNTVOLT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_separate_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_CPU,
+		},
+		.datasheet_name = "voltage0",
+	},
+	{
+		.type = IIO_VOLTAGE,
+		.indexed = 1,
+		.channel = 1,
+		.address = RTQ6056_REG_BUSVOLT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_separate_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.scan_index = 1,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_CPU,
+		},
+		.datasheet_name = "voltage1",
+	},
+	{
+		.type = IIO_POWER,
+		.indexed = 1,
+		.channel = 2,
+		.address = RTQ6056_REG_POWER,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.scan_index = 2,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_CPU,
+		},
+		.datasheet_name = "power2",
+	},
+	{
+		.type = IIO_CURRENT,
+		.indexed = 1,
+		.channel = 3,
+		.address = RTQ6056_REG_CURRENT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.scan_index = 3,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_CPU,
+		},
+		.datasheet_name = "current3",
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(RTQ6056_MAX_CHANNEL),
+};
+
+static int rtq6056_adc_read_channel(struct rtq6056_priv *priv,
+				    struct iio_chan_spec const *ch,
+				    int *val)
+{
+	struct device *dev = priv->dev;
+	unsigned int addr = ch->address;
+	unsigned int regval;
+	int ret;
+
+	pm_runtime_get_sync(dev);
+	ret = regmap_read(priv->regmap, addr, &regval);
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put(dev);
+	if (ret)
+		return ret;
+
+	/* Power and VBUS is unsigned 16-bit, others are signed 16-bit */
+	if (addr == RTQ6056_REG_BUSVOLT || addr == RTQ6056_REG_POWER)
+		*val = regval;
+	else
+		*val = sign_extend32(regval, 16);
+
+	return IIO_VAL_INT;
+}
+
+static int rtq6056_adc_read_scale(struct iio_chan_spec const *ch, int *val,
+				  int *val2)
+{
+	switch (ch->address) {
+	case RTQ6056_REG_SHUNTVOLT:
+		/* VSHUNT lsb  2.5uV */
+		*val = 2500;
+		*val2 = 1000000;
+		return IIO_VAL_FRACTIONAL;
+	case RTQ6056_REG_BUSVOLT:
+		/* VBUS lsb 1.25mV */
+		*val = 1250;
+		*val2 = 1000;
+		return IIO_VAL_FRACTIONAL;
+	case RTQ6056_REG_POWER:
+		/* Power lsb 25mW */
+		*val = 25;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+/*
+ * Sample frequency for channel VSHUNT and VBUS. The indices correspond
+ * with the bit value expected by the chip. And it can be found at
+ * https://www.richtek.com/assets/product_file/RTQ6056/DSQ6056-00.pdf
+ */
+static const int rtq6056_samp_freq_list[] = {
+	7194, 4926, 3717, 1904, 964, 485, 243, 122,
+};
+
+static int rtq6056_adc_set_samp_freq(struct rtq6056_priv *priv,
+				     struct iio_chan_spec const *ch, int val)
+{
+	unsigned int selector;
+	int *ct, ret;
+
+	if (val > 7194 || val < 122)
+		return -EINVAL;
+
+	if (ch->address == RTQ6056_REG_SHUNTVOLT) {
+		ct = &priv->vshuntct_us;
+	} else if (ch->address == RTQ6056_REG_BUSVOLT) {
+		ct = &priv->vbusct_us;
+	} else
+		return -EINVAL;
+
+	selector = find_closest_descending(val, rtq6056_samp_freq_list,
+					   ARRAY_SIZE(rtq6056_samp_freq_list));
+
+	if (ch->address == RTQ6056_REG_SHUNTVOLT) {
+		ret = regmap_update_bits(priv->regmap, RTQ6056_REG_CONFIG,
+					 RTQ6056_CONFIG_VSHUNTCT_MASK,
+					 RTQ6056_CONFIG_VSHUNTCT(selector));
+	} else {
+		ret = regmap_update_bits(priv->regmap, RTQ6056_REG_CONFIG,
+					 RTQ6056_CONFIG_VBUSCT_MASK,
+					 RTQ6056_CONFIG_VBUSCT(selector));
+	}
+	if (ret)
+		return ret;
+
+	*ct = 1000000 / rtq6056_samp_freq_list[selector];
+
+	return 0;
+}
+
+/*
+ * Available averaging rate for rtq6056. The indices correspond with the bit
+ * value expected by the chip. And it can be found at
+ * https://www.richtek.com/assets/product_file/RTQ6056/DSQ6056-00.pdf
+ */
+static const int rtq6056_avg_sample_list[] = {
+	1, 4, 16, 64, 128, 256, 512, 1024,
+};
+
+static int rtq6056_adc_set_average(struct rtq6056_priv *priv, int val)
+{
+	unsigned int selector;
+	int ret;
+
+	if (val > 1024 || val < 1)
+		return -EINVAL;
+
+	selector = find_closest(val, rtq6056_avg_sample_list,
+				ARRAY_SIZE(rtq6056_avg_sample_list));
+
+	ret = regmap_update_bits(priv->regmap, RTQ6056_REG_CONFIG,
+				 RTQ6056_CONFIG_AVG_MASK,
+				 RTQ6056_CONFIG_AVG(selector));
+
+	if (ret)
+		return ret;
+
+	priv->avg_sample = rtq6056_avg_sample_list[selector];
+
+	return 0;
+}
+
+static int rtq6056_adc_get_sample_freq(struct rtq6056_priv *priv,
+				       struct iio_chan_spec const *ch, int *val)
+{
+	int sample_time;
+
+	if (ch->address == RTQ6056_REG_SHUNTVOLT)
+		sample_time = priv->vshuntct_us;
+	else if (ch->address == RTQ6056_REG_BUSVOLT)
+		sample_time = priv->vbusct_us;
+	else {
+		sample_time = priv->vshuntct_us + priv->vbusct_us;
+		sample_time *= priv->avg_sample;
+	}
+
+	*val = 1000000 / sample_time;
+
+	return IIO_VAL_INT;
+}
+
+static int rtq6056_adc_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan, int *val,
+				int *val2, long mask)
+{
+	struct rtq6056_priv *priv = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		return rtq6056_adc_read_channel(priv, chan, val);
+	case IIO_CHAN_INFO_SCALE:
+		return rtq6056_adc_read_scale(chan, val, val2);
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*val = priv->avg_sample;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		return rtq6056_adc_get_sample_freq(priv, chan, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int rtq6056_adc_read_avail(struct iio_dev *indio_dev,
+				  struct iio_chan_spec const *chan,
+				  const int **vals, int *type, int *length,
+				  long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*vals = rtq6056_samp_freq_list;
+		*type = IIO_VAL_INT;
+		*length = ARRAY_SIZE(rtq6056_samp_freq_list);
+		return IIO_AVAIL_LIST;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*vals = rtq6056_avg_sample_list;
+		*type = IIO_VAL_INT;
+		*length = ARRAY_SIZE(rtq6056_avg_sample_list);
+		return IIO_AVAIL_LIST;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int rtq6056_adc_write_raw(struct iio_dev *indio_dev,
+				 struct iio_chan_spec const *chan, int val,
+				 int val2, long mask)
+{
+	struct rtq6056_priv *priv = iio_priv(indio_dev);
+	int ret;
+
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		ret = rtq6056_adc_set_samp_freq(priv, chan, val);
+		break;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		ret = rtq6056_adc_set_average(priv, val);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	iio_device_release_direct_mode(indio_dev);
+
+	return ret;
+}
+
+static int rtq6056_set_shunt_resistor(struct rtq6056_priv *priv,
+				      int resistor_uohm)
+{
+	unsigned int calib_val;
+	int ret;
+
+	if (resistor_uohm <= 0) {
+		dev_err(priv->dev, "Invalid resistor [%d]\n", resistor_uohm);
+		return -EINVAL;
+	}
+
+	/* calibration = 5120000 / (Rshunt (uOhm) * current lsb (1mA)) */
+	calib_val = 5120000 / resistor_uohm;
+	ret = regmap_write(priv->regmap, RTQ6056_REG_CALIBRATION, calib_val);
+	if (ret)
+		return ret;
+
+	priv->shunt_resistor_uohm = resistor_uohm;
+
+	return 0;
+}
+
+static ssize_t shunt_resistor_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct rtq6056_priv *priv = iio_priv(dev_to_iio_dev(dev));
+	int vals[2] = { priv->shunt_resistor_uohm, 1000000 };
+
+	return iio_format_value(buf, IIO_VAL_FRACTIONAL, 1, vals);
+}
+
+static ssize_t shunt_resistor_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 rtq6056_priv *priv = iio_priv(indio_dev);
+	int val, val_fract, ret;
+
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
+
+	ret = iio_str_to_fixpoint(buf, 100000, &val, &val_fract);
+	if (ret)
+		goto out_store;
+
+	ret = rtq6056_set_shunt_resistor(priv, val * 1000000 + val_fract);
+
+out_store:
+	iio_device_release_direct_mode(indio_dev);
+
+	return ret ?: len;
+}
+
+static IIO_DEVICE_ATTR_RW(shunt_resistor, 0);
+
+static struct attribute *rtq6056_attributes[] = {
+	&iio_dev_attr_shunt_resistor.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group rtq6056_attribute_group = {
+	.attrs = rtq6056_attributes,
+};
+
+static const struct iio_info rtq6056_info = {
+	.attrs = &rtq6056_attribute_group,
+	.read_raw = rtq6056_adc_read_raw,
+	.read_avail = rtq6056_adc_read_avail,
+	.write_raw = rtq6056_adc_write_raw,
+};
+
+static irqreturn_t rtq6056_buffer_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct rtq6056_priv *priv = iio_priv(indio_dev);
+	struct device *dev = priv->dev;
+	struct {
+		u16 vals[RTQ6056_MAX_CHANNEL];
+		s64 timestamp __aligned(8);
+	} data;
+	unsigned int raw;
+	int i = 0, bit, ret;
+
+	memset(&data, 0, sizeof(data));
+
+	pm_runtime_get_sync(dev);
+
+	for_each_set_bit(bit, indio_dev->active_scan_mask, indio_dev->masklength) {
+		unsigned int addr = rtq6056_channels[bit].address;
+
+		ret = regmap_read(priv->regmap, addr, &raw);
+		if (ret)
+			goto out;
+
+		data.vals[i++] = raw;
+	}
+
+	iio_push_to_buffers_with_timestamp(indio_dev, &data, iio_get_time_ns(indio_dev));
+
+out:
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put(dev);
+
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static void rtq6056_enter_shutdown_state(void *dev)
+{
+	struct rtq6056_priv *priv = dev_get_drvdata(dev);
+
+	/* Enter shutdown state */
+	regmap_update_bits(priv->regmap, RTQ6056_REG_CONFIG,
+			   RTQ6056_CONFIG_OPMODE_MASK,
+			   RTQ6056_CONFIG_OPMODE(0));
+}
+
+static bool rtq6056_is_readable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case RTQ6056_REG_CONFIG ... RTQ6056_REG_ALERTLIMIT:
+	case RTQ6056_REG_MANUFACTID ... RTQ6056_REG_DIEID:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool rtq6056_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case RTQ6056_REG_CONFIG:
+	case RTQ6056_REG_CALIBRATION ... RTQ6056_REG_ALERTLIMIT:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config rtq6056_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 16,
+	.val_format_endian = REGMAP_ENDIAN_BIG,
+	.max_register = RTQ6056_REG_DIEID,
+	.readable_reg = rtq6056_is_readable_reg,
+	.writeable_reg = rtq6056_is_writeable_reg,
+};
+
+static int rtq6056_probe(struct i2c_client *i2c)
+{
+	struct iio_dev *indio_dev;
+	struct rtq6056_priv *priv;
+	struct device *dev = &i2c->dev;
+	struct regmap *regmap;
+	unsigned int vendor_id, shunt_resistor_uohm;
+	int ret;
+
+	if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_SMBUS_WORD_DATA))
+		return -EOPNOTSUPP;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	priv = iio_priv(indio_dev);
+	priv->dev = dev;
+	priv->vshuntct_us = priv->vbusct_us = 1037;
+	priv->avg_sample = 1;
+	i2c_set_clientdata(i2c, priv);
+
+	regmap = devm_regmap_init_i2c(i2c, &rtq6056_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(dev, "Failed to init regmap\n");
+		return PTR_ERR(regmap);
+	}
+
+	priv->regmap = regmap;
+
+	ret = regmap_read(regmap, RTQ6056_REG_MANUFACTID, &vendor_id);
+	if (ret) {
+		dev_err(dev, "Failed to get manufacturer info: %d\n", ret);
+		return ret;
+	}
+
+	if (vendor_id != RTQ6056_VENDOR_ID) {
+		dev_err(dev, "Invalid vendor id 0x%04x\n", vendor_id);
+		return -ENODEV;
+	}
+
+	/*
+	 * By default, configure average sample as 1, bus and shunt conversion
+	 * time as 1037 microsecond, and operating mode to all on.
+	 */
+	ret = regmap_write(regmap, RTQ6056_REG_CONFIG, RTQ6056_DEFAULT_CONFIG);
+	if (ret) {
+		dev_err(dev, "Failed to enable continuous sensing: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_add_action_or_reset(dev, rtq6056_enter_shutdown_state, dev);
+	if (ret)
+		return ret;
+
+	/* By default, use 2000 micro-Ohm resistor */
+	shunt_resistor_uohm = 2000;
+	device_property_read_u32(dev, "shunt-resistor-micro-ohms",
+				 &shunt_resistor_uohm);
+
+	ret = rtq6056_set_shunt_resistor(priv, shunt_resistor_uohm);
+	if (ret) {
+		dev_err(dev, "Failed to init shunt resistor: %d\n", ret);
+		goto err;
+	}
+
+	indio_dev->name = "rtq6056";
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = rtq6056_channels;
+	indio_dev->num_channels = ARRAY_SIZE(rtq6056_channels);
+	indio_dev->info = &rtq6056_info;
+
+	ret = iio_map_array_register(indio_dev, rtq6056_maps);
+	if (ret) {
+		dev_err(dev, "Failed to register iio map: %d\n", ret);
+		goto err;
+	}
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+					 &rtq6056_buffer_trigger_handler, NULL);
+
+	if (ret) {
+		dev_err(dev, "Failed to allocate iio trigger buffer: %d\n",
+			ret);
+		goto err;
+	}
+
+	ret = devm_iio_device_register(dev, indio_dev);
+	if (ret) {
+		dev_err(dev, "Failed to register iio device: %d\n", ret);
+		goto err;
+	}
+
+	return 0;
+
+err:
+	return ret;
+}
+
+static const struct of_device_id rtq6056_device_match[] = {
+	{ .compatible = "richtek,rtq6056" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, rtq6056_device_match);
+
+static struct i2c_driver rtq6056_driver = {
+	.driver = {
+		.name = "rtq6056",
+		.of_match_table = rtq6056_device_match,
+	},
+	.probe_new = rtq6056_probe,
+};
+module_i2c_driver(rtq6056_driver);
+
+MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
+MODULE_DESCRIPTION("Richtek RTQ6056 Driver");
+MODULE_LICENSE("GPL v2");
-- 
2.18.0