i2c: add sc18is600 driver

Submitted by Sebastian Reichel on March 29, 2017, 2:03 p.m.

Details

Message ID 20170329140339.22501-1-sre@kernel.org
State Superseded
Headers show

Commit Message

Sebastian Reichel March 29, 2017, 2:03 p.m.
This adds an I²C master driver for SPI -> I²C bus bridge chips.
It currently supports NXP's SC18IS600 and SC18IS601, as well as
Silicon Labs' CP2120. The driver was only tested on SC18IS600.

Signed-off-By: Sebastian Reichel <sre@kernel.org>
---
 .../devicetree/bindings/i2c/i2c-cp2120.txt         |   1 +
 .../devicetree/bindings/i2c/i2c-sc18is600.txt      |  62 +++
 drivers/i2c/busses/Kconfig                         |  10 +
 drivers/i2c/busses/Makefile                        |   1 +
 drivers/i2c/busses/i2c-sc18is600.c                 | 572 +++++++++++++++++++++
 5 files changed, 646 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-cp2120.txt
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-sc18is600.txt
 create mode 100644 drivers/i2c/busses/i2c-sc18is600.c

Comments

Rob Herring April 3, 2017, 2:54 p.m.
On Wed, Mar 29, 2017 at 04:03:39PM +0200, Sebastian Reichel wrote:
> This adds an I²C master driver for SPI -> I²C bus bridge chips.
> It currently supports NXP's SC18IS600 and SC18IS601, as well as
> Silicon Labs' CP2120. The driver was only tested on SC18IS600.
> 
> Signed-off-By: Sebastian Reichel <sre@kernel.org>
> ---
>  .../devicetree/bindings/i2c/i2c-cp2120.txt         |   1 +
>  .../devicetree/bindings/i2c/i2c-sc18is600.txt      |  62 +++

Acked-by: Rob Herring <robh@kernel.org> 

>  drivers/i2c/busses/Kconfig                         |  10 +
>  drivers/i2c/busses/Makefile                        |   1 +
>  drivers/i2c/busses/i2c-sc18is600.c                 | 572 +++++++++++++++++++++
>  5 files changed, 646 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/i2c/i2c-cp2120.txt
>  create mode 100644 Documentation/devicetree/bindings/i2c/i2c-sc18is600.txt
>  create mode 100644 drivers/i2c/busses/i2c-sc18is600.c
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Sebastian Reichel April 28, 2017, 11:31 a.m.
Hi,

ping? This is really useful on RPi, which has only has I2C
controllers with broken clock stretching support.

-- Sebastian

On Wed, Mar 29, 2017 at 04:03:39PM +0200, Sebastian Reichel wrote:
> This adds an I²C master driver for SPI -> I²C bus bridge chips.
> It currently supports NXP's SC18IS600 and SC18IS601, as well as
> Silicon Labs' CP2120. The driver was only tested on SC18IS600.
> 
> Signed-off-By: Sebastian Reichel <sre@kernel.org>
> ---
>  .../devicetree/bindings/i2c/i2c-cp2120.txt         |   1 +
>  .../devicetree/bindings/i2c/i2c-sc18is600.txt      |  62 +++
>  drivers/i2c/busses/Kconfig                         |  10 +
>  drivers/i2c/busses/Makefile                        |   1 +
>  drivers/i2c/busses/i2c-sc18is600.c                 | 572 +++++++++++++++++++++
>  5 files changed, 646 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/i2c/i2c-cp2120.txt
>  create mode 100644 Documentation/devicetree/bindings/i2c/i2c-sc18is600.txt
>  create mode 100644 drivers/i2c/busses/i2c-sc18is600.c
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-cp2120.txt b/Documentation/devicetree/bindings/i2c/i2c-cp2120.txt
> new file mode 100644
> index 000000000000..95e06e74f288
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/i2c-cp2120.txt
> @@ -0,0 +1 @@
> +Please see binding for i2c-sc18is600
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-sc18is600.txt b/Documentation/devicetree/bindings/i2c/i2c-sc18is600.txt
> new file mode 100644
> index 000000000000..d0d9e680a5d6
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/i2c-sc18is600.txt
> @@ -0,0 +1,62 @@
> +NXP SC18IS600 and Silabs CP2120 - SPI to I2C bus bridge
> +
> +NXP SC18IS600 is a SPI slave chip, which implements an I²C host,
> +also known as SPI to I²C bus bridge. SC18IS601 is the same chip,
> +but has an external clock input instead of using a builtin
> +oscillator. CP2120 is a similar chip from Silabs, which implements
> +the same interface as NXP's SC18IS600.
> +
> +Required properties:
> +  - compatible: Should contain one of
> +      * "nxp,sc18is600"
> +      * "nxp,sc18is601"
> +      * "silabs,cp2120"
> +  - reg: address of the chip on SPI bus
> +  - interrupts: Interrupt specifier. Refer to interrupt bindings.
> +  - #address-cells: Should be 1.
> +  - #size-cells: Should be 0.
> +
> +Required properties for sc18is601:
> +  - clkin: Clock specifier for CLKIN pin
> +
> +Optional properties:
> +  - clock-frequency:
> +    Desired I2C bus frequency in Hz, otherwise defaults to 100 KHz
> +  - reset-gpios
> +    GPIO specifier for reset pin, which is active low.
> +  - vdd-supply
> +    Regulator specifier for VDD supply (3.3V).
> +  - Child nodes conforming to i2c bus binding
> +
> +Example:
> +
> +&spi_controller {
> +	sc18is600: i2c@0 {
> +		compatible = "nxp,sc18is600";
> +		spi-max-frequency = <700000>; /* 700KHz */
> +		spi-cpol;
> +		spi-cpha;
> +		reg = <0>;
> +
> +		vdd-supply = <&regulator_v33>;
> +
> +		interrupt-parent = <&socgpio>;
> +		interrupts = <25 0x2>;
> +
> +		reset-gpios = <&i2cgpio1 9 GPIO_ACTIVE_LOW>;
> +
> +		clock-frequency = <100000>; /* 100KHz */
> +
> +		#address-cells = <0x1>;
> +		#size-cells = <0x0>;
> +	};
> +};
> +
> +&sc18is600 {
> +	i2c_device@42 {
> +		compatible = "some,i2c-device";
> +		reg = <0x42>;
> +	};
> +
> +	...
> +};
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index 8adc0f1d7ad0..3e6386ff8de3 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -210,6 +210,16 @@ config I2C_NFORCE2_S4985
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called i2c-nforce2-s4985.
>  
> +config I2C_SC18IS600
> +	tristate "NXP SC18IS600"
> +	depends on SPI && REGMAP
> +	help
> +	  If you say yes to this option, support will be included for the
> +	  NXP SC18IS600 SPI to I2C-bus interface.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called i2c-sc18is600.
> +
>  config I2C_SIS5595
>  	tristate "SiS 5595"
>  	depends on PCI
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index 30b60855fbcd..29971aebd238 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -18,6 +18,7 @@ obj-$(CONFIG_I2C_ISMT)		+= i2c-ismt.o
>  obj-$(CONFIG_I2C_NFORCE2)	+= i2c-nforce2.o
>  obj-$(CONFIG_I2C_NFORCE2_S4985)	+= i2c-nforce2-s4985.o
>  obj-$(CONFIG_I2C_PIIX4)		+= i2c-piix4.o
> +obj-$(CONFIG_I2C_SC18IS600)	+= i2c-sc18is600.o
>  obj-$(CONFIG_I2C_SIS5595)	+= i2c-sis5595.o
>  obj-$(CONFIG_I2C_SIS630)	+= i2c-sis630.o
>  obj-$(CONFIG_I2C_SIS96X)	+= i2c-sis96x.o
> diff --git a/drivers/i2c/busses/i2c-sc18is600.c b/drivers/i2c/busses/i2c-sc18is600.c
> new file mode 100644
> index 000000000000..e4d4b3caf3a9
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-sc18is600.c
> @@ -0,0 +1,572 @@
> +/*
> + * NXP SC18IS600 SPI to I2C bus interface driver
> + *
> + * Copyright (C) 2017 Sebastian Reichel <sre@kernel.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * Datasheets:
> + *  - http://www.nxp.com/documents/data_sheet/SC18IS600.pdf
> + *  - https://www.silabs.com/documents/public/data-sheets/CP2120.pdf
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
> +
> +#define SC18IS600_I2C_PM_TIMEOUT 1000 /* ms */
> +#define SC18IS600_DEFAULT_FREQ 100000
> +
> +#define SC18IS600_CMD_WR	0x00 /* write */
> +#define SC18IS600_CMD_RD	0x01 /* read */
> +#define SC18IS600_CMD_WR_RD	0x02 /* read after write */
> +#define SC18IS600_CMD_WR_WR	0x03 /* write after write */
> +#define SC18IS600_CMD_RDBUF	0x06 /* read buffer */
> +#define CP2120_CMD_WRMULTI	0x09 /* write to multiple slaves */
> +#define SC18IS600_CMD_SPICON	0x18 /* spi endianess configuration */
> +#define SC18IS600_CMD_REG_WR	0x20 /* write register */
> +#define SC18IS600_CMD_REG_RD	0x21 /* read register */
> +#define SC18IS600_CMD_PWRDWN	0x30 /* power down */
> +#define CP2120_CMD_REVISION	0x40 /* read revision */
> +
> +#define SC18IS600_REG_IO_CONFIG		0x00
> +#define SC18IS600_REG_IO_STATE		0x01
> +#define SC18IS600_REG_I2C_CLOCK		0x02
> +#define SC18IS600_REG_I2C_TIMEOUT	0x03
> +#define SC18IS600_REG_I2C_STAT		0x04
> +#define SC18IS600_REG_I2C_ADDR		0x05
> +#define SC18IS600_REG_I2C_BUFFER	0x06 /* only cp2120 */
> +#define SC18IS600_REG_IO_CONFIG2	0x07 /* only cp2120 */
> +#define SC18IS600_REG_EDGEINT		0x08 /* only cp2120 */
> +#define SC18IS600_REG_I2C_TIMEOUT2	0x09 /* only cp2120 */
> +
> +#define SC18IS600_STAT_OK		0xF0
> +#define SC18IS600_STAT_NAK_ADDR		0xF1
> +#define SC18IS600_STAT_NAK_DATA		0xF2
> +#define SC18IS600_STAT_BUSY		0xF3
> +#define SC18IS600_STAT_TIMEOUT		0xF8
> +#define SC18IS600_STAT_SIZE		0xF9
> +#define SC18IS600_STAT_TIMEOUT2		0xFA /* only cp2120 */
> +#define SC18IS600_STAT_BLOCKED		0xFB /* only cp2120 */
> +
> +#define CMD_BUFFER_SIZE 5
> +
> +enum chiptype {
> +	SPI2I2C_SC18IS600,
> +	SPI2I2C_SC18IS601,
> +	SPI2I2C_CP2120,
> +};
> +
> +struct chipdesc {
> +	u8  type;
> +	u32 max_spi_speed;
> +	u32 buffer_size;
> +	u32 clock_base;
> +	u32 timeout_base;
> +	const struct regmap_config *regmap_cfg;
> +};
> +
> +static bool sc18is600_writeable_reg(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	case SC18IS600_REG_I2C_STAT:
> +	case SC18IS600_REG_I2C_BUFFER:
> +		return false;
> +	default:
> +		return true;
> +	}
> +}
> +
> +static const struct regmap_config sc18is600_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +
> +	.max_register = 0x05,
> +	.writeable_reg = sc18is600_writeable_reg,
> +};
> +
> +static const struct regmap_config cp2120_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +
> +	.max_register = 0x09,
> +	.writeable_reg = sc18is600_writeable_reg,
> +};
> +
> +/*
> + * Note: The sc18is600's datasheet promises 1.2MHz SPI support, but my chip did
> + * not behave correctly at that speed. It received the bytes correctly, but
> + * just sent them back instead of interpreting them correctly. At 800 KHz I
> + * still got a few errors (about 1%) and at 700 KHz everything works smoothly.
> + */
> +static const struct chipdesc chip_sc18is600 = {
> +	.type = SPI2I2C_SC18IS600,
> +	.max_spi_speed = 700000,
> +	.buffer_size = 96,
> +	.clock_base = 1843200,
> +	.buffer_size = 96,
> +	.clock_base = 1843200,
> +	.timeout_base = 1125, /* 112.5 Hz */
> +	.regmap_cfg = &sc18is600_regmap_config,
> +};
> +
> +static const struct chipdesc chip_sc18is601 = {
> +	.type = SPI2I2C_SC18IS601,
> +	.max_spi_speed = 3000000,
> +	.buffer_size = 96,
> +	.clock_base = 0,
> +	.timeout_base = 1125, /* 112.5 Hz */
> +	.regmap_cfg = &sc18is600_regmap_config,
> +};
> +
> +static const struct chipdesc chip_cp2120 = {
> +	.type = SPI2I2C_CP2120,
> +	.max_spi_speed = 1000000,
> +	.buffer_size = 255,
> +	.clock_base = 2000000,
> +	.timeout_base = 1280, /* 128 Hz */
> +	.regmap_cfg = &cp2120_regmap_config,
> +};
> +
> +struct sc18is600dev {
> +	struct i2c_adapter adapter;
> +	struct completion completion;
> +	struct spi_device *spi;
> +	struct regmap *regmap;
> +	const struct chipdesc *chip;
> +	struct gpio_desc *reset;
> +	struct regulator *vdd;
> +	struct clk *clk;
> +	u32 clock_base;
> +	u32 i2c_clock_frequency;
> +	int state;
> +};
> +
> +static irqreturn_t sc18is600_irq_handler(int this_irq, void *data)
> +{
> +	struct sc18is600dev *dev = data;
> +	int err;
> +
> +	err = regmap_read(dev->regmap, SC18IS600_REG_I2C_STAT, &dev->state);
> +	if (err)
> +		return IRQ_NONE;
> +
> +	dev_vdbg(&dev->spi->dev, "irq received, stat=%08x", dev->state);
> +
> +	/* no irq is generated for busy state, so ignore this irq */
> +	if (dev->state == SC18IS600_STAT_BUSY)
> +		return IRQ_NONE;
> +
> +	complete(&dev->completion);
> +	return IRQ_HANDLED;
> +}
> +
> +static int reg_read(void *context, unsigned int reg, unsigned int *val)
> +{
> +	struct device *dev = context;
> +	struct spi_device *spi = to_spi_device(dev);
> +	u8 txbuffer[2] = { SC18IS600_CMD_REG_RD, reg & 0xff };
> +	u8 rxbuffer[1];
> +	int err;
> +
> +	err = spi_write_then_read(spi, txbuffer, sizeof(txbuffer),
> +				       rxbuffer, sizeof(rxbuffer));
> +	if (err)
> +		return err;
> +
> +	*val = rxbuffer[0];
> +
> +	return 0;
> +}
> +
> +static int reg_write(void *context, unsigned int reg, unsigned int val)
> +{
> +	struct device *dev = context;
> +	struct spi_device *spi = to_spi_device(dev);
> +	u8 txbuffer[3] = { SC18IS600_CMD_REG_WR, reg & 0xff, val & 0xff };
> +
> +	return spi_write(spi, txbuffer, sizeof(txbuffer));
> +}
> +
> +static struct regmap_bus regmap_sc18is600_bus = {
> +	.reg_write = reg_write,
> +	.reg_read = reg_read,
> +	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
> +	.val_format_endian_default = REGMAP_ENDIAN_BIG,
> +};
> +
> +static void sc18is600_setup_clock_frequency(struct sc18is600dev *dev)
> +{
> +	int reg = DIV_ROUND_UP(dev->clock_base, dev->i2c_clock_frequency);
> +
> +	if (reg < 5)
> +		reg = 5;
> +	if (reg > 255)
> +		reg = 255;
> +
> +	dev_dbg(&dev->spi->dev, "i2c clock frequency: %08x", reg);
> +	regmap_write(dev->regmap, SC18IS600_REG_I2C_CLOCK, reg);
> +}
> +
> +static void sc18is600_setup_timeout(struct sc18is600dev *dev,
> +				    bool enable, int timeout_ms)
> +{
> +	int timeout = DIV_ROUND_UP(timeout_ms * dev->chip->timeout_base, 10000);
> +	u8 reg;
> +
> +	if (timeout <= 0)
> +		timeout = 1;
> +	if (timeout > 255)
> +		timeout = 255;
> +
> +	reg = (timeout & 0x7F) << 1;
> +	reg |= (!!enable);
> +
> +	dev_dbg(&dev->spi->dev, "i2c timeout: %08x", reg);
> +	regmap_write(dev->regmap, SC18IS600_REG_I2C_TIMEOUT, reg);
> +}
> +
> +static void sc18is600_reset(struct sc18is600dev *dev)
> +{
> +	if (dev->reset) {
> +		gpiod_set_value_cansleep(dev->reset, 1);
> +		usleep_range(50, 100);
> +		gpiod_set_value_cansleep(dev->reset, 0);
> +		usleep_range(50, 100);
> +	}
> +
> +	sc18is600_setup_clock_frequency(dev);
> +	sc18is600_setup_timeout(dev, true, 500);
> +}
> +
> +static int sc18is600_read(struct sc18is600dev *dev, struct i2c_msg *msg)
> +{
> +	u8 header[] = { SC18IS600_CMD_RD, msg->len, msg->addr << 1 };
> +	struct spi_transfer xfer[1] = { 0 };
> +
> +	xfer[0].tx_buf = header;
> +	xfer[0].len = sizeof(header);
> +
> +	dev_dbg(&dev->spi->dev, "r(addr=%x, len=%d)", msg->addr, msg->len);
> +	return spi_sync_transfer(dev->spi, xfer, 1);
> +}
> +
> +static int sc18is600_write(struct sc18is600dev *dev, struct i2c_msg *msg)
> +{
> +	u8 header[] = { SC18IS600_CMD_WR, msg->len, msg->addr << 1 };
> +	struct spi_transfer xfer[2] = { 0 };
> +
> +	xfer[0].tx_buf = header;
> +	xfer[0].len = sizeof(header);
> +
> +	xfer[1].tx_buf = msg->buf;
> +	xfer[1].len = msg->len;
> +
> +	dev_dbg(&dev->spi->dev, "w(addr=%x, len=%d)", msg->addr, msg->len);
> +	return spi_sync_transfer(dev->spi, xfer, 2);
> +}
> +
> +static int sc18is600_read_after_write(struct sc18is600dev *dev,
> +				      struct i2c_msg *msg1,
> +				      struct i2c_msg *msg2)
> +{
> +	u8 header1[] =
> +		{ SC18IS600_CMD_WR_RD, msg1->len, msg2->len, msg1->addr << 1 };
> +	u8 header2[] = { msg2->addr << 1 };
> +	struct spi_transfer xfer[3] = { 0 };
> +
> +	xfer[0].tx_buf = header1;
> +	xfer[0].len = sizeof(header1);
> +
> +	xfer[1].tx_buf = msg1->buf;
> +	xfer[1].len = msg1->len;
> +
> +	xfer[2].tx_buf = header2;
> +	xfer[2].len = sizeof(header2);
> +
> +	dev_dbg(&dev->spi->dev, "w(addr=%x, len=%d) + r(addr=%x, len=%d)",
> +		msg1->addr, msg1->len, msg2->addr, msg2->len);
> +	return spi_sync_transfer(dev->spi, xfer, 3);
> +}
> +
> +static int sc18is600_write_after_write(struct sc18is600dev *dev,
> +				       struct i2c_msg *msg1,
> +				       struct i2c_msg *msg2)
> +{
> +	u8 header1[] =
> +		{ SC18IS600_CMD_WR_WR, msg1->len, msg2->len, msg1->addr << 1 };
> +	u8 header2[] = { msg2->addr << 1 };
> +	struct spi_transfer xfer[4] = { 0 };
> +
> +	xfer[0].tx_buf = header1;
> +	xfer[0].len = sizeof(header1);
> +
> +	xfer[1].tx_buf = msg1->buf;
> +	xfer[1].len = msg1->len;
> +
> +	xfer[2].tx_buf = header2;
> +	xfer[2].len = sizeof(header2);
> +
> +	xfer[3].tx_buf = msg2->buf;
> +	xfer[3].len = msg2->len;
> +
> +	dev_dbg(&dev->spi->dev, "w(addr=%x, len=%d) + w(addr=%x, len=%d)",
> +		msg1->addr, msg1->len, msg2->addr, msg2->len);
> +	return spi_sync_transfer(dev->spi, xfer, 4);
> +}
> +
> +static int sc18is600_read_buffer(struct sc18is600dev *dev, struct i2c_msg *msg)
> +{
> +	static const u8 read_buffer_cmd = SC18IS600_REG_I2C_BUFFER;
> +
> +	return spi_write_then_read(dev->spi, &read_buffer_cmd, 1,
> +				   msg->buf, msg->len);
> +}
> +
> +static int sc18is600_xfer(struct i2c_adapter *adapter,
> +			  struct i2c_msg *msgs, int num)
> +{
> +	struct sc18is600dev *dev = adapter->algo_data;
> +	int read_operations = 0;
> +	int i, err;
> +
> +	for (i = 0; i < num; i++) {
> +		if (msgs[i].len > dev->chip->buffer_size)
> +			return -EOPNOTSUPP;
> +
> +		/* chip only support standard read & write */
> +		if (msgs[i].flags & ~I2C_M_RD)
> +			return -EOPNOTSUPP;
> +
> +		if (msgs[i].flags & I2C_M_RD)
> +			read_operations++;
> +	}
> +
> +	reinit_completion(&dev->completion);
> +
> +	if (num == 1 && read_operations == 1)
> +		err = sc18is600_read(dev, &msgs[0]);
> +	else if (num == 1)
> +		err = sc18is600_write(dev, &msgs[0]);
> +	else if (num == 2 && read_operations == 1)
> +		err = sc18is600_read_after_write(dev, &msgs[0], &msgs[1]);
> +	else if (num == 2)
> +		err = sc18is600_write_after_write(dev, &msgs[0], &msgs[1]);
> +	else
> +		return -EOPNOTSUPP;
> +
> +	if (err) {
> +		dev_err(&dev->spi->dev, "spi transfer failed: %d", err);
> +		return err;
> +	}
> +
> +	err = wait_for_completion_timeout(&dev->completion, adapter->timeout);
> +	if (!err) {
> +		dev_warn(&dev->spi->dev,
> +			 "timeout waiting for irq, poll status register");
> +		dev->state = SC18IS600_STAT_BUSY;
> +		regmap_read(dev->regmap, SC18IS600_REG_I2C_STAT, &dev->state);
> +	}
> +
> +	switch (dev->state) {
> +	case SC18IS600_STAT_OK:
> +		break;
> +	case SC18IS600_STAT_NAK_ADDR:
> +		return -EIO;
> +	case SC18IS600_STAT_NAK_DATA:
> +		return -EREMOTEIO;
> +	case SC18IS600_STAT_SIZE:
> +		return -EINVAL;
> +	case SC18IS600_STAT_TIMEOUT:
> +		return -ETIMEDOUT;
> +	case SC18IS600_STAT_TIMEOUT2:
> +		return -ETIMEDOUT;
> +	case SC18IS600_STAT_BLOCKED:
> +		return -ETIMEDOUT;
> +	default:
> +	case SC18IS600_STAT_BUSY:
> +		dev_err(&dev->spi->dev, "device hangup detected, reset!");
> +		sc18is600_reset(dev);
> +		return -EAGAIN;
> +	}
> +
> +	if (!read_operations)
> +		return 0;
> +
> +	err = sc18is600_read_buffer(dev, &msgs[num-1]);
> +	if (err)
> +		return err;
> +
> +	return num;
> +}
> +
> +static u32 sc18is600_func(struct i2c_adapter *adap)
> +{
> +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +}
> +
> +static const struct i2c_algorithm sc18is600_algorithm = {
> +	.master_xfer	= sc18is600_xfer,
> +	.functionality	= sc18is600_func,
> +};
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id sc18is600_of_match[] = {
> +	{ .compatible = "nxp,sc18is600", .data = &chip_sc18is600 },
> +	{ .compatible = "nxp,sc18is601", .data = &chip_sc18is601 },
> +	{ .compatible = "silabs,cp2120", .data = &chip_cp2120 },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, sc18is600_of_match);
> +#endif
> +
> +static int sc18is600_probe(struct spi_device *spi)
> +{
> +	const struct of_device_id *of_id;
> +	struct sc18is600dev *dev;
> +	int err;
> +
> +	of_id = of_match_device(sc18is600_of_match, &spi->dev);
> +	if (!of_id)
> +		return -ENODEV;
> +
> +	dev = devm_kzalloc(&spi->dev, sizeof(*dev), GFP_KERNEL);
> +	if (dev == NULL)
> +		return -ENOMEM;
> +	spi_set_drvdata(spi, dev);
> +
> +	init_completion(&dev->completion);
> +
> +	dev->spi = spi;
> +	dev->adapter.owner = THIS_MODULE;
> +	dev->adapter.class = I2C_CLASS_DEPRECATED;
> +	dev->adapter.algo = &sc18is600_algorithm;
> +	dev->adapter.algo_data = dev;
> +	dev->adapter.dev.parent = &spi->dev;
> +	dev->chip = of_id->data;
> +
> +	snprintf(dev->adapter.name, sizeof(dev->adapter.name),
> +		 "SC18IS600 at SPI %02d device %02d",
> +		 spi->master->bus_num, spi->chip_select);
> +
> +	spi->bits_per_word = 8;
> +	spi->mode = SPI_MODE_3;
> +	spi->max_speed_hz = dev->chip->max_spi_speed;
> +
> +	err = spi_setup(spi);
> +	if (err)
> +		return err;
> +
> +	dev->reset = devm_gpiod_get_optional(&spi->dev, "reset", GPIOD_OUT_LOW);
> +	if (IS_ERR(dev->reset)) {
> +		err = PTR_ERR(dev->reset);
> +		dev_err(&spi->dev, "Failed to reset gpio, err: %d\n", err);
> +		return err;
> +	}
> +
> +	err = devm_request_threaded_irq(&spi->dev, spi->irq, NULL,
> +					sc18is600_irq_handler,
> +					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
> +					"sc18is600", dev);
> +	if (err) {
> +		dev_err(&spi->dev, "Failed to request irq, err: %d\n", err);
> +		return err;
> +	}
> +
> +	dev->regmap = devm_regmap_init(&dev->spi->dev,
> +			       &regmap_sc18is600_bus, &dev->spi->dev,
> +			       dev->chip->regmap_cfg);
> +	if (IS_ERR(dev->regmap)) {
> +		err = PTR_ERR(dev->regmap);
> +		dev_err(&spi->dev, "Failed to init regmap, err: %d\n", err);
> +		return err;
> +	}
> +
> +	err = device_property_read_u32(&spi->dev, "clock-frequency",
> +				       &dev->i2c_clock_frequency);
> +	if (err) {
> +		dev->i2c_clock_frequency = SC18IS600_DEFAULT_FREQ;
> +		dev_dbg(&spi->dev, "using default frequency %u\n",
> +			dev->i2c_clock_frequency);
> +	}
> +
> +	dev->vdd = devm_regulator_get(&spi->dev, "vdd");
> +	if (IS_ERR(dev->vdd)) {
> +		err = PTR_ERR(dev->vdd);
> +		dev_err(&spi->dev, "could not acquire vdd: %d\n", err);
> +		return err;
> +	}
> +
> +	if (!dev->chip->clock_base) {
> +		dev->clk = devm_clk_get(&spi->dev, "clkin");
> +		if (IS_ERR(dev->clk)) {
> +			err = PTR_ERR(dev->clk);
> +			dev_err(&spi->dev, "could not acquire vdd: %d\n", err);
> +			return err;
> +		}
> +
> +		clk_prepare_enable(dev->clk);
> +
> +		dev->clock_base = clk_get_rate(dev->clk) / 4;
> +	} else {
> +		dev->clock_base = dev->chip->clock_base;
> +	}
> +
> +	err = regulator_enable(dev->vdd);
> +	if (err) {
> +		dev_err(&spi->dev, "could not enable vdd: %d\n", err);
> +		return err;
> +	}
> +
> +	sc18is600_reset(dev);
> +
> +	err = i2c_add_adapter(&dev->adapter);
> +	if (err)
> +		goto out_disable_regulator;
> +
> +	return 0;
> +
> +out_disable_regulator:
> +	regulator_disable(dev->vdd);
> +	return err;
> +}
> +
> +static int sc18is600_remove(struct spi_device *spi)
> +{
> +	struct sc18is600dev *dev = spi_get_drvdata(spi);
> +
> +	i2c_del_adapter(&dev->adapter);
> +
> +	regulator_disable(dev->vdd);
> +
> +	return 0;
> +}
> +
> +static struct spi_driver sc18is600_driver = {
> +	.probe		= sc18is600_probe,
> +	.remove		= sc18is600_remove,
> +	.driver		= {
> +		.name	= "i2c-sc18is600",
> +		.of_match_table = of_match_ptr(sc18is600_of_match),
> +	},
> +};
> +module_spi_driver(sc18is600_driver);
> +
> +MODULE_AUTHOR("Sebastian Reichel <sre@kernel.org>");
> +MODULE_DESCRIPTION("NXP SC18IS600 I2C bus adapter");
> +MODULE_LICENSE("GPL");
> -- 
> 2.11.0
>

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diff --git a/Documentation/devicetree/bindings/i2c/i2c-cp2120.txt b/Documentation/devicetree/bindings/i2c/i2c-cp2120.txt
new file mode 100644
index 000000000000..95e06e74f288
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-cp2120.txt
@@ -0,0 +1 @@ 
+Please see binding for i2c-sc18is600
diff --git a/Documentation/devicetree/bindings/i2c/i2c-sc18is600.txt b/Documentation/devicetree/bindings/i2c/i2c-sc18is600.txt
new file mode 100644
index 000000000000..d0d9e680a5d6
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-sc18is600.txt
@@ -0,0 +1,62 @@ 
+NXP SC18IS600 and Silabs CP2120 - SPI to I2C bus bridge
+
+NXP SC18IS600 is a SPI slave chip, which implements an I²C host,
+also known as SPI to I²C bus bridge. SC18IS601 is the same chip,
+but has an external clock input instead of using a builtin
+oscillator. CP2120 is a similar chip from Silabs, which implements
+the same interface as NXP's SC18IS600.
+
+Required properties:
+  - compatible: Should contain one of
+      * "nxp,sc18is600"
+      * "nxp,sc18is601"
+      * "silabs,cp2120"
+  - reg: address of the chip on SPI bus
+  - interrupts: Interrupt specifier. Refer to interrupt bindings.
+  - #address-cells: Should be 1.
+  - #size-cells: Should be 0.
+
+Required properties for sc18is601:
+  - clkin: Clock specifier for CLKIN pin
+
+Optional properties:
+  - clock-frequency:
+    Desired I2C bus frequency in Hz, otherwise defaults to 100 KHz
+  - reset-gpios
+    GPIO specifier for reset pin, which is active low.
+  - vdd-supply
+    Regulator specifier for VDD supply (3.3V).
+  - Child nodes conforming to i2c bus binding
+
+Example:
+
+&spi_controller {
+	sc18is600: i2c@0 {
+		compatible = "nxp,sc18is600";
+		spi-max-frequency = <700000>; /* 700KHz */
+		spi-cpol;
+		spi-cpha;
+		reg = <0>;
+
+		vdd-supply = <&regulator_v33>;
+
+		interrupt-parent = <&socgpio>;
+		interrupts = <25 0x2>;
+
+		reset-gpios = <&i2cgpio1 9 GPIO_ACTIVE_LOW>;
+
+		clock-frequency = <100000>; /* 100KHz */
+
+		#address-cells = <0x1>;
+		#size-cells = <0x0>;
+	};
+};
+
+&sc18is600 {
+	i2c_device@42 {
+		compatible = "some,i2c-device";
+		reg = <0x42>;
+	};
+
+	...
+};
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 8adc0f1d7ad0..3e6386ff8de3 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -210,6 +210,16 @@  config I2C_NFORCE2_S4985
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-nforce2-s4985.
 
+config I2C_SC18IS600
+	tristate "NXP SC18IS600"
+	depends on SPI && REGMAP
+	help
+	  If you say yes to this option, support will be included for the
+	  NXP SC18IS600 SPI to I2C-bus interface.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called i2c-sc18is600.
+
 config I2C_SIS5595
 	tristate "SiS 5595"
 	depends on PCI
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 30b60855fbcd..29971aebd238 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -18,6 +18,7 @@  obj-$(CONFIG_I2C_ISMT)		+= i2c-ismt.o
 obj-$(CONFIG_I2C_NFORCE2)	+= i2c-nforce2.o
 obj-$(CONFIG_I2C_NFORCE2_S4985)	+= i2c-nforce2-s4985.o
 obj-$(CONFIG_I2C_PIIX4)		+= i2c-piix4.o
+obj-$(CONFIG_I2C_SC18IS600)	+= i2c-sc18is600.o
 obj-$(CONFIG_I2C_SIS5595)	+= i2c-sis5595.o
 obj-$(CONFIG_I2C_SIS630)	+= i2c-sis630.o
 obj-$(CONFIG_I2C_SIS96X)	+= i2c-sis96x.o
diff --git a/drivers/i2c/busses/i2c-sc18is600.c b/drivers/i2c/busses/i2c-sc18is600.c
new file mode 100644
index 000000000000..e4d4b3caf3a9
--- /dev/null
+++ b/drivers/i2c/busses/i2c-sc18is600.c
@@ -0,0 +1,572 @@ 
+/*
+ * NXP SC18IS600 SPI to I2C bus interface driver
+ *
+ * Copyright (C) 2017 Sebastian Reichel <sre@kernel.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * Datasheets:
+ *  - http://www.nxp.com/documents/data_sheet/SC18IS600.pdf
+ *  - https://www.silabs.com/documents/public/data-sheets/CP2120.pdf
+ */
+
+#include <linux/clk.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#define SC18IS600_I2C_PM_TIMEOUT 1000 /* ms */
+#define SC18IS600_DEFAULT_FREQ 100000
+
+#define SC18IS600_CMD_WR	0x00 /* write */
+#define SC18IS600_CMD_RD	0x01 /* read */
+#define SC18IS600_CMD_WR_RD	0x02 /* read after write */
+#define SC18IS600_CMD_WR_WR	0x03 /* write after write */
+#define SC18IS600_CMD_RDBUF	0x06 /* read buffer */
+#define CP2120_CMD_WRMULTI	0x09 /* write to multiple slaves */
+#define SC18IS600_CMD_SPICON	0x18 /* spi endianess configuration */
+#define SC18IS600_CMD_REG_WR	0x20 /* write register */
+#define SC18IS600_CMD_REG_RD	0x21 /* read register */
+#define SC18IS600_CMD_PWRDWN	0x30 /* power down */
+#define CP2120_CMD_REVISION	0x40 /* read revision */
+
+#define SC18IS600_REG_IO_CONFIG		0x00
+#define SC18IS600_REG_IO_STATE		0x01
+#define SC18IS600_REG_I2C_CLOCK		0x02
+#define SC18IS600_REG_I2C_TIMEOUT	0x03
+#define SC18IS600_REG_I2C_STAT		0x04
+#define SC18IS600_REG_I2C_ADDR		0x05
+#define SC18IS600_REG_I2C_BUFFER	0x06 /* only cp2120 */
+#define SC18IS600_REG_IO_CONFIG2	0x07 /* only cp2120 */
+#define SC18IS600_REG_EDGEINT		0x08 /* only cp2120 */
+#define SC18IS600_REG_I2C_TIMEOUT2	0x09 /* only cp2120 */
+
+#define SC18IS600_STAT_OK		0xF0
+#define SC18IS600_STAT_NAK_ADDR		0xF1
+#define SC18IS600_STAT_NAK_DATA		0xF2
+#define SC18IS600_STAT_BUSY		0xF3
+#define SC18IS600_STAT_TIMEOUT		0xF8
+#define SC18IS600_STAT_SIZE		0xF9
+#define SC18IS600_STAT_TIMEOUT2		0xFA /* only cp2120 */
+#define SC18IS600_STAT_BLOCKED		0xFB /* only cp2120 */
+
+#define CMD_BUFFER_SIZE 5
+
+enum chiptype {
+	SPI2I2C_SC18IS600,
+	SPI2I2C_SC18IS601,
+	SPI2I2C_CP2120,
+};
+
+struct chipdesc {
+	u8  type;
+	u32 max_spi_speed;
+	u32 buffer_size;
+	u32 clock_base;
+	u32 timeout_base;
+	const struct regmap_config *regmap_cfg;
+};
+
+static bool sc18is600_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case SC18IS600_REG_I2C_STAT:
+	case SC18IS600_REG_I2C_BUFFER:
+		return false;
+	default:
+		return true;
+	}
+}
+
+static const struct regmap_config sc18is600_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.max_register = 0x05,
+	.writeable_reg = sc18is600_writeable_reg,
+};
+
+static const struct regmap_config cp2120_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.max_register = 0x09,
+	.writeable_reg = sc18is600_writeable_reg,
+};
+
+/*
+ * Note: The sc18is600's datasheet promises 1.2MHz SPI support, but my chip did
+ * not behave correctly at that speed. It received the bytes correctly, but
+ * just sent them back instead of interpreting them correctly. At 800 KHz I
+ * still got a few errors (about 1%) and at 700 KHz everything works smoothly.
+ */
+static const struct chipdesc chip_sc18is600 = {
+	.type = SPI2I2C_SC18IS600,
+	.max_spi_speed = 700000,
+	.buffer_size = 96,
+	.clock_base = 1843200,
+	.buffer_size = 96,
+	.clock_base = 1843200,
+	.timeout_base = 1125, /* 112.5 Hz */
+	.regmap_cfg = &sc18is600_regmap_config,
+};
+
+static const struct chipdesc chip_sc18is601 = {
+	.type = SPI2I2C_SC18IS601,
+	.max_spi_speed = 3000000,
+	.buffer_size = 96,
+	.clock_base = 0,
+	.timeout_base = 1125, /* 112.5 Hz */
+	.regmap_cfg = &sc18is600_regmap_config,
+};
+
+static const struct chipdesc chip_cp2120 = {
+	.type = SPI2I2C_CP2120,
+	.max_spi_speed = 1000000,
+	.buffer_size = 255,
+	.clock_base = 2000000,
+	.timeout_base = 1280, /* 128 Hz */
+	.regmap_cfg = &cp2120_regmap_config,
+};
+
+struct sc18is600dev {
+	struct i2c_adapter adapter;
+	struct completion completion;
+	struct spi_device *spi;
+	struct regmap *regmap;
+	const struct chipdesc *chip;
+	struct gpio_desc *reset;
+	struct regulator *vdd;
+	struct clk *clk;
+	u32 clock_base;
+	u32 i2c_clock_frequency;
+	int state;
+};
+
+static irqreturn_t sc18is600_irq_handler(int this_irq, void *data)
+{
+	struct sc18is600dev *dev = data;
+	int err;
+
+	err = regmap_read(dev->regmap, SC18IS600_REG_I2C_STAT, &dev->state);
+	if (err)
+		return IRQ_NONE;
+
+	dev_vdbg(&dev->spi->dev, "irq received, stat=%08x", dev->state);
+
+	/* no irq is generated for busy state, so ignore this irq */
+	if (dev->state == SC18IS600_STAT_BUSY)
+		return IRQ_NONE;
+
+	complete(&dev->completion);
+	return IRQ_HANDLED;
+}
+
+static int reg_read(void *context, unsigned int reg, unsigned int *val)
+{
+	struct device *dev = context;
+	struct spi_device *spi = to_spi_device(dev);
+	u8 txbuffer[2] = { SC18IS600_CMD_REG_RD, reg & 0xff };
+	u8 rxbuffer[1];
+	int err;
+
+	err = spi_write_then_read(spi, txbuffer, sizeof(txbuffer),
+				       rxbuffer, sizeof(rxbuffer));
+	if (err)
+		return err;
+
+	*val = rxbuffer[0];
+
+	return 0;
+}
+
+static int reg_write(void *context, unsigned int reg, unsigned int val)
+{
+	struct device *dev = context;
+	struct spi_device *spi = to_spi_device(dev);
+	u8 txbuffer[3] = { SC18IS600_CMD_REG_WR, reg & 0xff, val & 0xff };
+
+	return spi_write(spi, txbuffer, sizeof(txbuffer));
+}
+
+static struct regmap_bus regmap_sc18is600_bus = {
+	.reg_write = reg_write,
+	.reg_read = reg_read,
+	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
+	.val_format_endian_default = REGMAP_ENDIAN_BIG,
+};
+
+static void sc18is600_setup_clock_frequency(struct sc18is600dev *dev)
+{
+	int reg = DIV_ROUND_UP(dev->clock_base, dev->i2c_clock_frequency);
+
+	if (reg < 5)
+		reg = 5;
+	if (reg > 255)
+		reg = 255;
+
+	dev_dbg(&dev->spi->dev, "i2c clock frequency: %08x", reg);
+	regmap_write(dev->regmap, SC18IS600_REG_I2C_CLOCK, reg);
+}
+
+static void sc18is600_setup_timeout(struct sc18is600dev *dev,
+				    bool enable, int timeout_ms)
+{
+	int timeout = DIV_ROUND_UP(timeout_ms * dev->chip->timeout_base, 10000);
+	u8 reg;
+
+	if (timeout <= 0)
+		timeout = 1;
+	if (timeout > 255)
+		timeout = 255;
+
+	reg = (timeout & 0x7F) << 1;
+	reg |= (!!enable);
+
+	dev_dbg(&dev->spi->dev, "i2c timeout: %08x", reg);
+	regmap_write(dev->regmap, SC18IS600_REG_I2C_TIMEOUT, reg);
+}
+
+static void sc18is600_reset(struct sc18is600dev *dev)
+{
+	if (dev->reset) {
+		gpiod_set_value_cansleep(dev->reset, 1);
+		usleep_range(50, 100);
+		gpiod_set_value_cansleep(dev->reset, 0);
+		usleep_range(50, 100);
+	}
+
+	sc18is600_setup_clock_frequency(dev);
+	sc18is600_setup_timeout(dev, true, 500);
+}
+
+static int sc18is600_read(struct sc18is600dev *dev, struct i2c_msg *msg)
+{
+	u8 header[] = { SC18IS600_CMD_RD, msg->len, msg->addr << 1 };
+	struct spi_transfer xfer[1] = { 0 };
+
+	xfer[0].tx_buf = header;
+	xfer[0].len = sizeof(header);
+
+	dev_dbg(&dev->spi->dev, "r(addr=%x, len=%d)", msg->addr, msg->len);
+	return spi_sync_transfer(dev->spi, xfer, 1);
+}
+
+static int sc18is600_write(struct sc18is600dev *dev, struct i2c_msg *msg)
+{
+	u8 header[] = { SC18IS600_CMD_WR, msg->len, msg->addr << 1 };
+	struct spi_transfer xfer[2] = { 0 };
+
+	xfer[0].tx_buf = header;
+	xfer[0].len = sizeof(header);
+
+	xfer[1].tx_buf = msg->buf;
+	xfer[1].len = msg->len;
+
+	dev_dbg(&dev->spi->dev, "w(addr=%x, len=%d)", msg->addr, msg->len);
+	return spi_sync_transfer(dev->spi, xfer, 2);
+}
+
+static int sc18is600_read_after_write(struct sc18is600dev *dev,
+				      struct i2c_msg *msg1,
+				      struct i2c_msg *msg2)
+{
+	u8 header1[] =
+		{ SC18IS600_CMD_WR_RD, msg1->len, msg2->len, msg1->addr << 1 };
+	u8 header2[] = { msg2->addr << 1 };
+	struct spi_transfer xfer[3] = { 0 };
+
+	xfer[0].tx_buf = header1;
+	xfer[0].len = sizeof(header1);
+
+	xfer[1].tx_buf = msg1->buf;
+	xfer[1].len = msg1->len;
+
+	xfer[2].tx_buf = header2;
+	xfer[2].len = sizeof(header2);
+
+	dev_dbg(&dev->spi->dev, "w(addr=%x, len=%d) + r(addr=%x, len=%d)",
+		msg1->addr, msg1->len, msg2->addr, msg2->len);
+	return spi_sync_transfer(dev->spi, xfer, 3);
+}
+
+static int sc18is600_write_after_write(struct sc18is600dev *dev,
+				       struct i2c_msg *msg1,
+				       struct i2c_msg *msg2)
+{
+	u8 header1[] =
+		{ SC18IS600_CMD_WR_WR, msg1->len, msg2->len, msg1->addr << 1 };
+	u8 header2[] = { msg2->addr << 1 };
+	struct spi_transfer xfer[4] = { 0 };
+
+	xfer[0].tx_buf = header1;
+	xfer[0].len = sizeof(header1);
+
+	xfer[1].tx_buf = msg1->buf;
+	xfer[1].len = msg1->len;
+
+	xfer[2].tx_buf = header2;
+	xfer[2].len = sizeof(header2);
+
+	xfer[3].tx_buf = msg2->buf;
+	xfer[3].len = msg2->len;
+
+	dev_dbg(&dev->spi->dev, "w(addr=%x, len=%d) + w(addr=%x, len=%d)",
+		msg1->addr, msg1->len, msg2->addr, msg2->len);
+	return spi_sync_transfer(dev->spi, xfer, 4);
+}
+
+static int sc18is600_read_buffer(struct sc18is600dev *dev, struct i2c_msg *msg)
+{
+	static const u8 read_buffer_cmd = SC18IS600_REG_I2C_BUFFER;
+
+	return spi_write_then_read(dev->spi, &read_buffer_cmd, 1,
+				   msg->buf, msg->len);
+}
+
+static int sc18is600_xfer(struct i2c_adapter *adapter,
+			  struct i2c_msg *msgs, int num)
+{
+	struct sc18is600dev *dev = adapter->algo_data;
+	int read_operations = 0;
+	int i, err;
+
+	for (i = 0; i < num; i++) {
+		if (msgs[i].len > dev->chip->buffer_size)
+			return -EOPNOTSUPP;
+
+		/* chip only support standard read & write */
+		if (msgs[i].flags & ~I2C_M_RD)
+			return -EOPNOTSUPP;
+
+		if (msgs[i].flags & I2C_M_RD)
+			read_operations++;
+	}
+
+	reinit_completion(&dev->completion);
+
+	if (num == 1 && read_operations == 1)
+		err = sc18is600_read(dev, &msgs[0]);
+	else if (num == 1)
+		err = sc18is600_write(dev, &msgs[0]);
+	else if (num == 2 && read_operations == 1)
+		err = sc18is600_read_after_write(dev, &msgs[0], &msgs[1]);
+	else if (num == 2)
+		err = sc18is600_write_after_write(dev, &msgs[0], &msgs[1]);
+	else
+		return -EOPNOTSUPP;
+
+	if (err) {
+		dev_err(&dev->spi->dev, "spi transfer failed: %d", err);
+		return err;
+	}
+
+	err = wait_for_completion_timeout(&dev->completion, adapter->timeout);
+	if (!err) {
+		dev_warn(&dev->spi->dev,
+			 "timeout waiting for irq, poll status register");
+		dev->state = SC18IS600_STAT_BUSY;
+		regmap_read(dev->regmap, SC18IS600_REG_I2C_STAT, &dev->state);
+	}
+
+	switch (dev->state) {
+	case SC18IS600_STAT_OK:
+		break;
+	case SC18IS600_STAT_NAK_ADDR:
+		return -EIO;
+	case SC18IS600_STAT_NAK_DATA:
+		return -EREMOTEIO;
+	case SC18IS600_STAT_SIZE:
+		return -EINVAL;
+	case SC18IS600_STAT_TIMEOUT:
+		return -ETIMEDOUT;
+	case SC18IS600_STAT_TIMEOUT2:
+		return -ETIMEDOUT;
+	case SC18IS600_STAT_BLOCKED:
+		return -ETIMEDOUT;
+	default:
+	case SC18IS600_STAT_BUSY:
+		dev_err(&dev->spi->dev, "device hangup detected, reset!");
+		sc18is600_reset(dev);
+		return -EAGAIN;
+	}
+
+	if (!read_operations)
+		return 0;
+
+	err = sc18is600_read_buffer(dev, &msgs[num-1]);
+	if (err)
+		return err;
+
+	return num;
+}
+
+static u32 sc18is600_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm sc18is600_algorithm = {
+	.master_xfer	= sc18is600_xfer,
+	.functionality	= sc18is600_func,
+};
+
+#ifdef CONFIG_OF
+static const struct of_device_id sc18is600_of_match[] = {
+	{ .compatible = "nxp,sc18is600", .data = &chip_sc18is600 },
+	{ .compatible = "nxp,sc18is601", .data = &chip_sc18is601 },
+	{ .compatible = "silabs,cp2120", .data = &chip_cp2120 },
+	{},
+};
+MODULE_DEVICE_TABLE(of, sc18is600_of_match);
+#endif
+
+static int sc18is600_probe(struct spi_device *spi)
+{
+	const struct of_device_id *of_id;
+	struct sc18is600dev *dev;
+	int err;
+
+	of_id = of_match_device(sc18is600_of_match, &spi->dev);
+	if (!of_id)
+		return -ENODEV;
+
+	dev = devm_kzalloc(&spi->dev, sizeof(*dev), GFP_KERNEL);
+	if (dev == NULL)
+		return -ENOMEM;
+	spi_set_drvdata(spi, dev);
+
+	init_completion(&dev->completion);
+
+	dev->spi = spi;
+	dev->adapter.owner = THIS_MODULE;
+	dev->adapter.class = I2C_CLASS_DEPRECATED;
+	dev->adapter.algo = &sc18is600_algorithm;
+	dev->adapter.algo_data = dev;
+	dev->adapter.dev.parent = &spi->dev;
+	dev->chip = of_id->data;
+
+	snprintf(dev->adapter.name, sizeof(dev->adapter.name),
+		 "SC18IS600 at SPI %02d device %02d",
+		 spi->master->bus_num, spi->chip_select);
+
+	spi->bits_per_word = 8;
+	spi->mode = SPI_MODE_3;
+	spi->max_speed_hz = dev->chip->max_spi_speed;
+
+	err = spi_setup(spi);
+	if (err)
+		return err;
+
+	dev->reset = devm_gpiod_get_optional(&spi->dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(dev->reset)) {
+		err = PTR_ERR(dev->reset);
+		dev_err(&spi->dev, "Failed to reset gpio, err: %d\n", err);
+		return err;
+	}
+
+	err = devm_request_threaded_irq(&spi->dev, spi->irq, NULL,
+					sc18is600_irq_handler,
+					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					"sc18is600", dev);
+	if (err) {
+		dev_err(&spi->dev, "Failed to request irq, err: %d\n", err);
+		return err;
+	}
+
+	dev->regmap = devm_regmap_init(&dev->spi->dev,
+			       &regmap_sc18is600_bus, &dev->spi->dev,
+			       dev->chip->regmap_cfg);
+	if (IS_ERR(dev->regmap)) {
+		err = PTR_ERR(dev->regmap);
+		dev_err(&spi->dev, "Failed to init regmap, err: %d\n", err);
+		return err;
+	}
+
+	err = device_property_read_u32(&spi->dev, "clock-frequency",
+				       &dev->i2c_clock_frequency);
+	if (err) {
+		dev->i2c_clock_frequency = SC18IS600_DEFAULT_FREQ;
+		dev_dbg(&spi->dev, "using default frequency %u\n",
+			dev->i2c_clock_frequency);
+	}
+
+	dev->vdd = devm_regulator_get(&spi->dev, "vdd");
+	if (IS_ERR(dev->vdd)) {
+		err = PTR_ERR(dev->vdd);
+		dev_err(&spi->dev, "could not acquire vdd: %d\n", err);
+		return err;
+	}
+
+	if (!dev->chip->clock_base) {
+		dev->clk = devm_clk_get(&spi->dev, "clkin");
+		if (IS_ERR(dev->clk)) {
+			err = PTR_ERR(dev->clk);
+			dev_err(&spi->dev, "could not acquire vdd: %d\n", err);
+			return err;
+		}
+
+		clk_prepare_enable(dev->clk);
+
+		dev->clock_base = clk_get_rate(dev->clk) / 4;
+	} else {
+		dev->clock_base = dev->chip->clock_base;
+	}
+
+	err = regulator_enable(dev->vdd);
+	if (err) {
+		dev_err(&spi->dev, "could not enable vdd: %d\n", err);
+		return err;
+	}
+
+	sc18is600_reset(dev);
+
+	err = i2c_add_adapter(&dev->adapter);
+	if (err)
+		goto out_disable_regulator;
+
+	return 0;
+
+out_disable_regulator:
+	regulator_disable(dev->vdd);
+	return err;
+}
+
+static int sc18is600_remove(struct spi_device *spi)
+{
+	struct sc18is600dev *dev = spi_get_drvdata(spi);
+
+	i2c_del_adapter(&dev->adapter);
+
+	regulator_disable(dev->vdd);
+
+	return 0;
+}
+
+static struct spi_driver sc18is600_driver = {
+	.probe		= sc18is600_probe,
+	.remove		= sc18is600_remove,
+	.driver		= {
+		.name	= "i2c-sc18is600",
+		.of_match_table = of_match_ptr(sc18is600_of_match),
+	},
+};
+module_spi_driver(sc18is600_driver);
+
+MODULE_AUTHOR("Sebastian Reichel <sre@kernel.org>");
+MODULE_DESCRIPTION("NXP SC18IS600 I2C bus adapter");
+MODULE_LICENSE("GPL");