Message-Id: <20170701150831.20197-1-sre@kernel.org>
Date:   Sat,  1 Jul 2017 17:08:31 +0200
From:   Sebastian Reichel <sre@...nel.org>
To:     Sebastian Reichel <sre@...nel.org>,
        Wolfram Sang <wsa@...-dreams.de>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, linux-i2c@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCHv2] i2c: add sc18is600 driver

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.

Acked-by: Rob Herring <robh@...nel.org>
Signed-off-By: Sebastian Reichel <sre@...nel.org>
---
Changes since PATCHv1:
 * Reported by Julia Lawall / buildbot
  - fix double initializations of buffer_size and clock_base
 * Reported by Andy Shevchenko
  - Use clamp_val() instead of open coding
  - Simplify some statements
  - Use of_device_get_match_data() instead of of_match_device()
  - Check for clk_prepare_enable() failure
  - Introduce SC18IS600_CLK_DIVIDER define instead of magic number
  - Rename struct sc18is600dev *dev to *s600dev.
 * Reported by Wolfram Sang
  - Move config to "External I2C/SMBus adapter drivers"
  - Drop debug messages
  - Use -ENXIO on address NAK
 * Add support for I2C_M_IGNORE_NAK
---
 .../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                 | 575 +++++++++++++++++++++
 5 files changed, 649 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 144cbadc7c72..572ac87fd37a 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1123,6 +1123,16 @@ config I2C_ROBOTFUZZ_OSIF
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-osif.
 
+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_TAOS_EVM
 	tristate "TAOS evaluation module"
 	depends on TTY
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 30b60855fbcd..f3552dd3f91c 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -109,6 +109,7 @@ obj-$(CONFIG_I2C_DLN2)		+= i2c-dln2.o
 obj-$(CONFIG_I2C_PARPORT)	+= i2c-parport.o
 obj-$(CONFIG_I2C_PARPORT_LIGHT)	+= i2c-parport-light.o
 obj-$(CONFIG_I2C_ROBOTFUZZ_OSIF)	+= i2c-robotfuzz-osif.o
+obj-$(CONFIG_I2C_SC18IS600)	+= i2c-sc18is600.o
 obj-$(CONFIG_I2C_TAOS_EVM)	+= i2c-taos-evm.o
 obj-$(CONFIG_I2C_TINY_USB)	+= i2c-tiny-usb.o
 obj-$(CONFIG_I2C_VIPERBOARD)	+= i2c-viperboard.o
diff --git a/drivers/i2c/busses/i2c-sc18is600.c b/drivers/i2c/busses/i2c-sc18is600.c
new file mode 100644
index 000000000000..5da34f7aaf9b
--- /dev/null
+++ b/drivers/i2c/busses/i2c-sc18is600.c
@@ -0,0 +1,575 @@
+/*
+ * NXP SC18IS600 SPI to I2C bus interface driver
+ *
+ * Copyright (C) 2017 Sebastian Reichel <sre@...nel.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_CLK_DIVIDER 4
+
+#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 = 7372800 / SC18IS600_CLK_DIVIDER,
+	.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 *s600dev = data;
+	int err;
+
+	err = regmap_read(s600dev->regmap, SC18IS600_REG_I2C_STAT,
+			  &s600dev->state);
+	if (err)
+		return IRQ_NONE;
+
+	dev_vdbg(&s600dev->spi->dev, "irq received, stat=%08x", s600dev->state);
+
+	/* no irq is generated for busy state, so ignore this irq */
+	if (s600dev->state == SC18IS600_STAT_BUSY)
+		return IRQ_NONE;
+
+	complete(&s600dev->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 *s600dev)
+{
+	int reg = DIV_ROUND_UP(s600dev->clock_base,
+			       s600dev->i2c_clock_frequency);
+
+	clamp_val(reg, 5, 255);
+
+	dev_dbg(&s600dev->spi->dev, "i2c clock frequency: %08x", reg);
+	regmap_write(s600dev->regmap, SC18IS600_REG_I2C_CLOCK, reg);
+}
+
+static void sc18is600_setup_timeout(struct sc18is600dev *s600dev,
+				    bool enable, int timeout_ms)
+{
+	int timeout = DIV_ROUND_UP(timeout_ms * s600dev->chip->timeout_base,
+				   10000);
+	u8 reg;
+
+	clamp_val(timeout, 1, 255);
+
+	reg = ((timeout & 0x7F) << 1) | !!enable;
+
+	dev_dbg(&s600dev->spi->dev, "i2c timeout: %08x", reg);
+	regmap_write(s600dev->regmap, SC18IS600_REG_I2C_TIMEOUT, reg);
+}
+
+static void sc18is600_reset(struct sc18is600dev *s600dev)
+{
+	if (s600dev->reset) {
+		gpiod_set_value_cansleep(s600dev->reset, 1);
+		usleep_range(50, 100);
+		gpiod_set_value_cansleep(s600dev->reset, 0);
+		usleep_range(50, 100);
+	}
+
+	sc18is600_setup_clock_frequency(s600dev);
+	sc18is600_setup_timeout(s600dev, true, 500);
+}
+
+static int sc18is600_read(struct sc18is600dev *s600dev, 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);
+
+	return spi_sync_transfer(s600dev->spi, xfer, 1);
+}
+
+static int sc18is600_write(struct sc18is600dev *s600dev, 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;
+
+	return spi_sync_transfer(s600dev->spi, xfer, 2);
+}
+
+static int sc18is600_read_write(struct sc18is600dev *s600dev,
+				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);
+
+	return spi_sync_transfer(s600dev->spi, xfer, 3);
+}
+
+static int sc18is600_write_write(struct sc18is600dev *s600dev,
+				 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;
+
+	return spi_sync_transfer(s600dev->spi, xfer, 4);
+}
+
+static int sc18is600_read_buffer(struct sc18is600dev *s600dev,
+				 struct i2c_msg *msg)
+{
+	static const u8 read_buffer_cmd = SC18IS600_REG_I2C_BUFFER;
+
+	return spi_write_then_read(s600dev->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 *s600dev = adapter->algo_data;
+	int read_operations = 0;
+	bool ignore_nak = false;
+	int i, err;
+
+	for (i = 0; i < num; i++) {
+		if (msgs[i].len > s600dev->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(&s600dev->completion);
+
+	if (num == 1) {
+		if (msgs[0].flags & I2C_M_IGNORE_NAK)
+			ignore_nak = true;
+
+		if (read_operations == 1)
+			err = sc18is600_read(s600dev, &msgs[0]);
+		else
+			err = sc18is600_write(s600dev, &msgs[0]);
+	} else if (num == 2) {
+		if (read_operations == 1)
+			err = sc18is600_read_write(s600dev, &msgs[0], &msgs[1]);
+		else
+			err = sc18is600_write_write(s600dev, &msgs[0], &msgs[1]);
+	} else {
+		return -EOPNOTSUPP;
+	}
+
+	if (err) {
+		dev_err(&s600dev->spi->dev, "spi transfer failed: %d", err);
+		return err;
+	}
+
+	err = wait_for_completion_timeout(&s600dev->completion,
+					  adapter->timeout);
+	if (!err) {
+		dev_warn(&s600dev->spi->dev,
+			 "timeout waiting for irq, poll status register");
+		s600dev->state = SC18IS600_STAT_BUSY;
+		regmap_read(s600dev->regmap, SC18IS600_REG_I2C_STAT,
+			    &s600dev->state);
+	}
+
+	switch (s600dev->state) {
+	case SC18IS600_STAT_OK:
+		break;
+	case SC18IS600_STAT_NAK_ADDR:
+		return -ENXIO;
+	case SC18IS600_STAT_NAK_DATA:
+		if (ignore_nak)
+			break;
+		return -EREMOTEIO;
+	case SC18IS600_STAT_SIZE:
+		return -EINVAL;
+	case SC18IS600_STAT_TIMEOUT:
+	case SC18IS600_STAT_TIMEOUT2:
+	case SC18IS600_STAT_BLOCKED:
+		return -ETIMEDOUT;
+	default:
+	case SC18IS600_STAT_BUSY:
+		dev_err(&s600dev->spi->dev, "device hangup detected, reset!");
+		sc18is600_reset(s600dev);
+		return -EAGAIN;
+	}
+
+	if (!read_operations)
+		return 0;
+
+	err = sc18is600_read_buffer(s600dev, &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,
+};
+
+static int sc18is600_probe(struct spi_device *spi)
+{
+	struct sc18is600dev *s600dev;
+	int err;
+
+	s600dev = devm_kzalloc(&spi->dev, sizeof(*s600dev), GFP_KERNEL);
+	if (!s600dev)
+		return -ENOMEM;
+	spi_set_drvdata(spi, s600dev);
+
+	init_completion(&s600dev->completion);
+
+	s600dev->spi = spi;
+	s600dev->adapter.owner = THIS_MODULE;
+	s600dev->adapter.class = I2C_CLASS_DEPRECATED;
+	s600dev->adapter.algo = &sc18is600_algorithm;
+	s600dev->adapter.algo_data = s600dev;
+	s600dev->adapter.dev.parent = &spi->dev;
+	s600dev->chip = of_device_get_match_data(&spi->dev);
+
+	if (!s600dev->chip)
+		return -ENODEV;
+
+	snprintf(s600dev->adapter.name, sizeof(s600dev->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 = s600dev->chip->max_spi_speed;
+
+	err = spi_setup(spi);
+	if (err)
+		return err;
+
+	s600dev->reset = devm_gpiod_get_optional(&spi->dev, "reset",
+						 GPIOD_OUT_LOW);
+	if (IS_ERR(s600dev->reset)) {
+		err = PTR_ERR(s600dev->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", s600dev);
+	if (err) {
+		dev_err(&spi->dev, "Failed to request irq, err: %d\n", err);
+		return err;
+	}
+
+	s600dev->regmap = devm_regmap_init(&spi->dev,
+			       &regmap_sc18is600_bus, &spi->dev,
+			       s600dev->chip->regmap_cfg);
+	if (IS_ERR(s600dev->regmap)) {
+		err = PTR_ERR(s600dev->regmap);
+		dev_err(&spi->dev, "Failed to init regmap, err: %d\n", err);
+		return err;
+	}
+
+	err = device_property_read_u32(&spi->dev, "clock-frequency",
+				       &s600dev->i2c_clock_frequency);
+	if (err) {
+		s600dev->i2c_clock_frequency = SC18IS600_DEFAULT_FREQ;
+		dev_dbg(&spi->dev, "using default frequency %u\n",
+			s600dev->i2c_clock_frequency);
+	}
+
+	s600dev->vdd = devm_regulator_get(&spi->dev, "vdd");
+	if (IS_ERR(s600dev->vdd)) {
+		err = PTR_ERR(s600dev->vdd);
+		dev_err(&spi->dev, "could not acquire Vdd: %d\n", err);
+		return err;
+	}
+
+	if (!s600dev->chip->clock_base) {
+		s600dev->clk = devm_clk_get(&spi->dev, "clkin");
+		if (IS_ERR(s600dev->clk)) {
+			err = PTR_ERR(s600dev->clk);
+			dev_err(&spi->dev, "could not acquire clk: %d\n", err);
+			return err;
+		}
+
+		err = clk_prepare_enable(s600dev->clk);
+		if (err) {
+			dev_err(&spi->dev, "could not enable clk: %d\n", err);
+			return err;
+		}
+
+		s600dev->clock_base =
+			clk_get_rate(s600dev->clk) / SC18IS600_CLK_DIVIDER;
+	} else {
+		s600dev->clock_base = s600dev->chip->clock_base;
+	}
+
+	err = regulator_enable(s600dev->vdd);
+	if (err) {
+		dev_err(&spi->dev, "could not enable vdd: %d\n", err);
+		return err;
+	}
+
+	sc18is600_reset(s600dev);
+
+	err = i2c_add_adapter(&s600dev->adapter);
+	if (err)
+		goto out_disable_regulator;
+
+	return 0;
+
+out_disable_regulator:
+	regulator_disable(s600dev->vdd);
+	return err;
+}
+
+static int sc18is600_remove(struct spi_device *spi)
+{
+	struct sc18is600dev *s600dev = spi_get_drvdata(spi);
+
+	i2c_del_adapter(&s600dev->adapter);
+
+	regulator_disable(s600dev->vdd);
+
+	return 0;
+}
+
+#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 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@...nel.org>");
+MODULE_DESCRIPTION("NXP SC18IS600 I2C bus adapter");
+MODULE_LICENSE("GPL");
-- 
2.11.0

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