Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Michael Zaidman <michael.zaidman@gmail.com>
To:     jikos@kernel.org, benjamin.tissoires@redhat.com, wsa@kernel.org
Cc:     linux-kernel@vger.kernel.org, linux-input@vger.kernel.org,
        linux-i2c@vger.kernel.org,
        Michael Zaidman <michael.zaidman@gmail.com>
Subject: [PATCH v2 1/1] HID: ft260: add usb hid to i2c host bridge driver
Date:   Fri, 19 Feb 2021 18:36:44 +0200
Message-Id: <20210219163644.2811-2-michael.zaidman@gmail.com>
In-Reply-To: <20210219163644.2811-1-michael.zaidman@gmail.com>
References: <20210219163644.2811-1-michael.zaidman@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The FTDI FT260 chip implements USB to I2C/UART bridges through two
USB HID class interfaces. The first - for I2C, and the second for UART.
Each interface is independent, and the kernel detects it as a separate
USB hidraw device.

This commit adds I2C host adapter support.

Signed-off-by: Michael Zaidman <michael.zaidman@gmail.com>
---
 MAINTAINERS             |    7 +
 drivers/hid/Kconfig     |   11 +
 drivers/hid/Makefile    |    1 +
 drivers/hid/hid-ft260.c | 1053 +++++++++++++++++++++++++++++++++++++++
 drivers/hid/hid-ids.h   |    1 +
 5 files changed, 1073 insertions(+)
 create mode 100644 drivers/hid/hid-ft260.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 8a6fe5389d7d..30526cfd4994 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7328,6 +7328,13 @@ F:	fs/verity/
 F:	include/linux/fsverity.h
 F:	include/uapi/linux/fsverity.h
 
+FT260 FTDI USB-HID TO I2C BRIDGE DRIVER
+M:	Michael Zaidman <michael.zaidman@gmail.com>
+L:	linux-i2c@vger.kernel.org
+L:	linux-input@vger.kernel.org
+S:	Maintained
+F:	drivers/hid/hid-ft260.c
+
 FUJITSU LAPTOP EXTRAS
 M:	Jonathan Woithe <jwoithe@just42.net>
 L:	platform-driver-x86@vger.kernel.org
diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 786b71ef7738..b279c6130bc2 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -351,6 +351,17 @@ config HID_EZKEY
 	help
 	Support for Ezkey BTC 8193 keyboard.
 
+config HID_FT260
+	tristate "FTDI FT260 USB HID to I2C host support"
+	depends on USB_HID && HIDRAW && I2C
+	help
+	  Provides I2C host adapter functionality over USB-HID through FT260
+	  device. The customizable USB descriptor fields are exposed as sysfs
+	  attributes.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called hid-ft260.
+
 config HID_GEMBIRD
 	tristate "Gembird Joypad"
 	depends on HID
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index c4f6d5c613dc..6e24c37132ec 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -46,6 +46,7 @@ obj-$(CONFIG_HID_ELAN)		+= hid-elan.o
 obj-$(CONFIG_HID_ELECOM)	+= hid-elecom.o
 obj-$(CONFIG_HID_ELO)		+= hid-elo.o
 obj-$(CONFIG_HID_EZKEY)		+= hid-ezkey.o
+obj-$(CONFIG_HID_FT260)		+= hid-ft260.o
 obj-$(CONFIG_HID_GEMBIRD)	+= hid-gembird.o
 obj-$(CONFIG_HID_GFRM)		+= hid-gfrm.o
 obj-$(CONFIG_HID_GLORIOUS)  += hid-glorious.o
diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c
new file mode 100644
index 000000000000..047aa85a7c83
--- /dev/null
+++ b/drivers/hid/hid-ft260.c
@@ -0,0 +1,1053 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * hid-ft260.c - FTDI FT260 USB HID to I2C host bridge
+ *
+ * Copyright (c) 2021, Michael Zaidman <michaelz@xsightlabs.com>
+ *
+ * Data Sheet:
+ *   https://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT260.pdf
+ */
+
+#include "hid-ids.h"
+#include <linux/hidraw.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+
+#ifdef DEBUG
+static int ft260_debug = 1;
+#else
+static int ft260_debug;
+#endif
+module_param_named(debug, ft260_debug, int, 0600);
+MODULE_PARM_DESC(debug, "Toggle FT260 debugging messages");
+
+#define ft260_dbg(format, arg...)					  \
+	do {								  \
+		if (ft260_debug)					  \
+			pr_info("%s: " format, __func__, ##arg);	  \
+	} while (0)
+
+#define FT260_REPORT_MAX_LENGTH (64)
+#define FT260_I2C_DATA_REPORT_ID(len) (FT260_I2C_REPORT_MIN + (len - 1) / 4)
+/*
+ * The input report format assigns 62 bytes for the data payload, but ft260
+ * returns 60 and 2 in two separate transactions. To minimize transfer time
+ * in reading chunks mode, set the maximum read payload length to 60 bytes.
+ */
+#define FT260_RD_DATA_MAX (60)
+#define FT260_WR_DATA_MAX (60)
+
+/*
+ * Device interface configuration.
+ * The FT260 has 2 interfaces that are controlled by DCNF0 and DCNF1 pins.
+ * First implementes USB HID to I2C bridge function and
+ * second - USB HID to UART bridge function.
+ */
+enum {
+	FT260_MODE_ALL			= 0x00,
+	FT260_MODE_I2C			= 0x01,
+	FT260_MODE_UART			= 0x02,
+	FT260_MODE_BOTH			= 0x03,
+};
+
+/* Control pipe */
+enum {
+	FT260_GET_RQST_TYPE		= 0xA1,
+	FT260_GET_REPORT		= 0x01,
+	FT260_SET_RQST_TYPE		= 0x21,
+	FT260_SET_REPORT		= 0x09,
+	FT260_FEATURE			= 0x03,
+};
+
+/* Report IDs / Feature In */
+enum {
+	FT260_CHIP_VERSION		= 0xA0,
+	FT260_SYSTEM_SETTINGS		= 0xA1,
+	FT260_I2C_STATUS		= 0xC0,
+	FT260_I2C_READ_REQ		= 0xC2,
+	FT260_I2C_REPORT_MIN		= 0xD0,
+	FT260_I2C_REPORT_MAX		= 0xDE,
+	FT260_GPIO			= 0xB0,
+	FT260_UART_INTERRUPT_STATUS	= 0xB1,
+	FT260_UART_STATUS		= 0xE0,
+	FT260_UART_RI_DCD_STATUS	= 0xE1,
+	FT260_UART_REPORT		= 0xF0,
+};
+
+/* Feature Out */
+enum {
+	FT260_SET_CLOCK			= 0x01,
+	FT260_SET_I2C_MODE		= 0x02,
+	FT260_SET_UART_MODE		= 0x03,
+	FT260_ENABLE_INTERRUPT		= 0x05,
+	FT260_SELECT_GPIO2_FUNC		= 0x06,
+	FT260_ENABLE_UART_DCD_RI	= 0x07,
+	FT260_SELECT_GPIOA_FUNC		= 0x08,
+	FT260_SELECT_GPIOG_FUNC		= 0x09,
+	FT260_SET_INTERRUPT_TRIGGER	= 0x0A,
+	FT260_SET_SUSPEND_OUT_POLAR	= 0x0B,
+	FT260_ENABLE_UART_RI_WAKEUP	= 0x0C,
+	FT260_SET_UART_RI_WAKEUP_CFG	= 0x0D,
+	FT260_SET_I2C_RESET		= 0x20,
+	FT260_SET_I2C_CLOCK_SPEED	= 0x22,
+	FT260_SET_UART_RESET		= 0x40,
+	FT260_SET_UART_CONFIG		= 0x41,
+	FT260_SET_UART_BAUD_RATE	= 0x42,
+	FT260_SET_UART_DATA_BIT		= 0x43,
+	FT260_SET_UART_PARITY		= 0x44,
+	FT260_SET_UART_STOP_BIT		= 0x45,
+	FT260_SET_UART_BREAKING		= 0x46,
+	FT260_SET_UART_XON_XOFF		= 0x49,
+};
+
+/* Response codes in I2C status report */
+enum {
+	FT260_I2C_STATUS_SUCCESS	= 0x00,
+	FT260_I2C_STATUS_CTRL_BUSY	= 0x01,
+	FT260_I2C_STATUS_ERROR		= 0x02,
+	FT260_I2C_STATUS_ADDR_NO_ACK	= 0x04,
+	FT260_I2C_STATUS_DATA_NO_ACK	= 0x08,
+	FT260_I2C_STATUS_ARBITR_LOST	= 0x10,
+	FT260_I2C_STATUS_CTRL_IDLE	= 0x20,
+	FT260_I2C_STATUS_BUS_BUSY	= 0x40,
+};
+
+/* I2C Conditions flags */
+enum {
+	FT260_FLAG_NONE			= 0x00,
+	FT260_FLAG_START		= 0x02,
+	FT260_FLAG_START_REPEATED	= 0x03,
+	FT260_FLAG_STOP			= 0x04,
+	FT260_FLAG_START_STOP		= 0x06,
+	FT260_FLAG_START_STOP_REPEATED	= 0x07,
+};
+
+#define FT260_SET_REQUEST_VALUE(report_id) ((FT260_FEATURE << 8) | report_id)
+
+/* Feature In reports */
+
+struct ft260_get_chip_version_report {
+	u8 report;		/* FT260_CHIP_VERSION */
+	u8 chip_code[4];	/* FTDI chip identification code */
+	u8 reserved[8];
+} __packed;
+
+struct ft260_get_system_status_report {
+	u8 report;		/* FT260_SYSTEM_SETTINGS */
+	u8 chip_mode;		/* DCNF0 and DCNF1 status, bits 0-1 */
+	u8 clock_ctl;		/* 0 - 12MHz, 1 - 24MHz, 2 - 48MHz */
+	u8 suspend_status;	/* 0 - not suspended, 1 - suspended */
+	u8 pwren_status;	/* 0 - FT260 is not ready, 1 - ready */
+	u8 i2c_enable;		/* 0 - disabled, 1 - enabled */
+	u8 uart_mode;		/* 0 - OFF; 1 - RTS_CTS, 2 - DTR_DSR, */
+				/* 3 - XON_XOFF, 4 - No flow control */
+	u8 hid_over_i2c_en;	/* 0 - disabled, 1 - enabled */
+	u8 gpio2_function;	/* 0 - GPIO,  1 - SUSPOUT, */
+				/* 2 - PWREN, 4 - TX_LED */
+	u8 gpioA_function;	/* 0 - GPIO, 3 - TX_ACTIVE, 4 - TX_LED */
+	u8 gpioG_function;	/* 0 - GPIO, 2 - PWREN, */
+				/* 5 - RX_LED, 6 - BCD_DET */
+	u8 suspend_out_pol;	/* 0 - active-high, 1 - active-low */
+	u8 enable_wakeup_int;	/* 0 - disabled, 1 - enabled */
+	u8 intr_cond;		/* Interrupt trigger conditions */
+	u8 power_saving_en;	/* 0 - disabled, 1 - enabled */
+	u8 reserved[10];
+} __packed;
+
+struct ft260_get_i2c_status_report {
+	u8 report;		/* FT260_I2C_STATUS */
+	u8 bus_status;		/* I2C bus status */
+	__le16 clock;		/* I2C bus clock in range 60-3400 KHz */
+	u8 reserved;
+} __packed;
+
+/* Feature Out reports */
+
+struct ft260_set_system_clock_report {
+	u8 report;		/* FT260_SYSTEM_SETTINGS */
+	u8 request;		/* FT260_SET_CLOCK */
+	u8 clock_ctl;		/* 0 - 12MHz, 1 - 24MHz, 2 - 48MHz */
+} __packed;
+
+struct ft260_set_i2c_mode_report {
+	u8 report;		/* FT260_SYSTEM_SETTINGS */
+	u8 request;		/* FT260_SET_I2C_MODE */
+	u8 i2c_enable;		/* 0 - disabled, 1 - enabled */
+} __packed;
+
+struct ft260_set_uart_mode_report {
+	u8 report;		/* FT260_SYSTEM_SETTINGS */
+	u8 request;		/* FT260_SET_UART_MODE */
+	u8 uart_mode;		/* 0 - OFF; 1 - RTS_CTS, 2 - DTR_DSR, */
+				/* 3 - XON_XOFF, 4 - No flow control */
+} __packed;
+
+struct ft260_set_i2c_reset_report {
+	u8 report;		/* FT260_SYSTEM_SETTINGS */
+	u8 request;		/* FT260_SET_I2C_RESET */
+} __packed;
+
+struct ft260_set_i2c_speed_report {
+	u8 report;		/* FT260_SYSTEM_SETTINGS */
+	u8 request;		/* FT260_SET_I2C_CLOCK_SPEED */
+	__le16 clock;		/* I2C bus clock in range 60-3400 KHz */
+} __packed;
+
+/* Data transfer reports */
+
+struct ft260_i2c_write_request_report {
+	u8 report;		/* FT260_I2C_REPORT */
+	u8 address;		/* 7-bit I2C address */
+	u8 flag;		/* I2C transaction condition */
+	u8 length;		/* data payload length */
+	u8 data[60];		/* data payload */
+} __packed;
+
+struct ft260_i2c_read_request_report {
+	u8 report;		/* FT260_I2C_READ_REQ */
+	u8 address;		/* 7-bit I2C address */
+	u8 flag;		/* I2C transaction condition */
+	__le16 length;		/* data payload length */
+} __packed;
+
+struct ft260_i2c_input_report {
+	u8 report;		/* FT260_I2C_REPORT */
+	u8 length;		/* data payload length */
+	u8 data[2];		/* data payload */
+} __packed;
+
+static const struct hid_device_id ft260_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_FUTURE_TECHNOLOGY,
+			 USB_DEVICE_ID_FT260) },
+	{ /* END OF LIST */ }
+};
+MODULE_DEVICE_TABLE(hid, ft260_devices);
+
+struct ft260_device {
+	struct i2c_adapter adap;
+	struct hid_device *hdev;
+	struct completion wait;
+	struct mutex lock;
+	u8 write_buf[FT260_REPORT_MAX_LENGTH];
+	u8 *read_buf;
+	u16 read_idx;
+	u16 read_len;
+	u16 clock;
+};
+
+static int ft260_hid_feature_report_get(struct hid_device *hdev,
+					unsigned char report_id, u8 *data,
+					size_t len)
+{
+	u8 *buf;
+	int ret;
+
+	buf = kmalloc(len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = hid_hw_raw_request(hdev, report_id, buf, len, HID_FEATURE_REPORT,
+				 HID_REQ_GET_REPORT);
+	memcpy(data, buf, len);
+	kfree(buf);
+	return ret;
+}
+
+static int ft260_hid_feature_report_set(struct hid_device *hdev, u8 *data,
+					size_t len)
+{
+	u8 *buf;
+	int ret;
+
+	buf = kmemdup(data, len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	buf[0] = FT260_SYSTEM_SETTINGS;
+
+	ret = hid_hw_raw_request(hdev, buf[0], buf, len, HID_FEATURE_REPORT,
+				 HID_REQ_SET_REPORT);
+
+	kfree(buf);
+	return ret;
+}
+
+static int ft260_i2c_reset(struct hid_device *hdev)
+{
+	struct ft260_set_i2c_reset_report report;
+	int ret;
+
+	report.request = FT260_SET_I2C_RESET;
+
+	ret = ft260_hid_feature_report_set(hdev, (u8 *)&report, sizeof(report));
+	if (ret < 0) {
+		hid_err(hdev, "failed to reset I2C controller: %d\n", ret);
+		return ret;
+	}
+
+	ft260_dbg("done\n");
+	return ret;
+}
+
+static int ft260_xfer_status(struct ft260_device *dev)
+{
+	struct hid_device *hdev = dev->hdev;
+	struct ft260_get_i2c_status_report report;
+	int ret;
+
+	ret = ft260_hid_feature_report_get(hdev, FT260_I2C_STATUS,
+					   (u8 *)&report, sizeof(report));
+	if (ret < 0) {
+		hid_err(hdev, "failed to retrieve status: %d\n", ret);
+		return ret;
+	}
+
+	dev->clock = le16_to_cpu(report.clock);
+	ft260_dbg("bus_status %#02x, clock %u\n", report.bus_status,
+		  dev->clock);
+
+	if (report.bus_status & FT260_I2C_STATUS_CTRL_BUSY)
+		return -EAGAIN;
+
+	if (report.bus_status & FT260_I2C_STATUS_BUS_BUSY)
+		return -EBUSY;
+
+	if (report.bus_status & FT260_I2C_STATUS_ERROR)
+		return -EIO;
+
+	ret = -EIO;
+
+	if (report.bus_status & FT260_I2C_STATUS_ADDR_NO_ACK)
+		ft260_dbg("unacknowledged address\n");
+
+	if (report.bus_status & FT260_I2C_STATUS_DATA_NO_ACK)
+		ft260_dbg("unacknowledged data\n");
+
+	if (report.bus_status & FT260_I2C_STATUS_ARBITR_LOST)
+		ft260_dbg("arbitration loss\n");
+
+	if (report.bus_status & FT260_I2C_STATUS_CTRL_IDLE)
+		ret = 0;
+
+	return ret;
+}
+
+static int ft260_hid_output_report(struct hid_device *hdev, u8 *data,
+				   size_t len)
+{
+	u8 *buf;
+	int ret;
+
+	buf = kmemdup(data, len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = hid_hw_output_report(hdev, buf, len);
+
+	kfree(buf);
+	return ret;
+}
+
+static int ft260_hid_output_report_check_status(struct ft260_device *dev,
+						u8 *data, int len)
+{
+	int ret, usec, try = 3;
+	struct hid_device *hdev = dev->hdev;
+
+	ret = ft260_hid_output_report(hdev, data, len);
+	if (ret < 0) {
+		hid_err(hdev, "%s: failed to start transfer, ret %d\n",
+			__func__, ret);
+		ft260_i2c_reset(hdev);
+		return ret;
+	}
+
+	/* transfer time = 1 / clock(KHz) * 10 bits * bytes */
+	usec = 10000 / dev->clock * len;
+	usleep_range(usec, usec + 100);
+	ft260_dbg("wait %d usec, len %d\n", usec, len);
+	do {
+		ret = ft260_xfer_status(dev);
+		if (ret != -EAGAIN)
+			break;
+	} while (--try);
+
+	if (ret == 0 || ret == -EBUSY)
+		return 0;
+
+	ft260_i2c_reset(hdev);
+	return -EIO;
+}
+
+static int ft260_i2c_write(struct ft260_device *dev, u8 addr, u8 *data,
+			   int data_len, u8 flag)
+{
+	int len, ret, idx = 0;
+	struct hid_device *hdev = dev->hdev;
+	struct ft260_i2c_write_request_report *rep =
+		(struct ft260_i2c_write_request_report *)dev->write_buf;
+
+	do {
+		if (data_len <= FT260_WR_DATA_MAX)
+			len = data_len;
+		else
+			len = FT260_WR_DATA_MAX;
+
+		rep->report = FT260_I2C_DATA_REPORT_ID(len);
+		rep->address = addr;
+		rep->length = len;
+		rep->flag = flag;
+
+		memcpy(rep->data, &data[idx], len);
+
+		ft260_dbg("rep %#02x addr %#02x off %d len %d d[0] %#02x\n",
+			  rep->report, addr, idx, len, data[0]);
+
+		ret = ft260_hid_output_report_check_status(dev, (u8 *)rep,
+							   len + 4);
+		if (ret < 0) {
+			hid_err(hdev, "%s: failed to start transfer, ret %d\n",
+				__func__, ret);
+			return ret;
+		}
+
+		data_len -= len;
+		idx += len;
+
+	} while (data_len > 0);
+
+	return 0;
+}
+
+static int ft260_smbus_write(struct ft260_device *dev, u8 addr, u8 cmd,
+			     u8 *data, u8 data_len, u8 flag)
+{
+	int ret = 0;
+	int len = 4;
+
+	struct ft260_i2c_write_request_report *rep =
+		(struct ft260_i2c_write_request_report *)dev->write_buf;
+
+	rep->address = addr;
+	rep->data[0] = cmd;
+	rep->length = data_len + 1;
+	rep->flag = flag;
+	len += rep->length;
+
+	rep->report = FT260_I2C_DATA_REPORT_ID(len);
+
+	if (data_len > 0)
+		memcpy(&rep->data[1], data, data_len);
+
+	ft260_dbg("rep %#02x addr %#02x cmd %#02x datlen %d replen %d\n",
+		  rep->report, addr, cmd, rep->length, len);
+
+	ret = ft260_hid_output_report_check_status(dev, (u8 *)rep, len);
+
+	return ret;
+}
+
+static int ft260_i2c_read(struct ft260_device *dev, u8 addr, u8 *data,
+			  u16 len, u8 flag)
+{
+	struct ft260_i2c_read_request_report rep;
+	struct hid_device *hdev = dev->hdev;
+	int timeout;
+	int ret;
+
+	if (len > FT260_RD_DATA_MAX) {
+		hid_err(hdev, "%s: unsupported rd len: %d\n", __func__, len);
+		return -EINVAL;
+	}
+
+	dev->read_idx = 0;
+	dev->read_buf = data;
+	dev->read_len = len;
+
+	rep.report = FT260_I2C_READ_REQ;
+	rep.length = cpu_to_le16(len);
+	rep.address = addr;
+	rep.flag = flag;
+
+	ft260_dbg("rep %#02x addr %#02x len %d\n", rep.report, rep.address,
+		  rep.length);
+
+	reinit_completion(&dev->wait);
+
+	ret = ft260_hid_output_report(hdev, (u8 *)&rep, sizeof(rep));
+	if (ret < 0) {
+		hid_err(hdev, "%s: failed to start transaction, ret %d\n",
+			__func__, ret);
+		return ret;
+	}
+
+	timeout = msecs_to_jiffies(5000);
+	if (!wait_for_completion_timeout(&dev->wait, timeout)) {
+		ft260_i2c_reset(hdev);
+		return -ETIMEDOUT;
+	}
+
+	ret = ft260_xfer_status(dev);
+	if (ret == 0)
+		return 0;
+
+	ft260_i2c_reset(hdev);
+	return -EIO;
+}
+
+/*
+ * A random read operation is implemented as a dummy write operation, followed
+ * by a current address read operation. The dummy write operation is used to
+ * load the target byte address into the current byte address counter, from
+ * which the subsequent current address read operation then reads.
+ */
+static int ft260_i2c_write_read(struct ft260_device *dev, struct i2c_msg *msgs)
+{
+	int len, ret;
+	u16 left_len = msgs[1].len;
+	u8 *read_buf = msgs[1].buf;
+	u8 addr = msgs[0].addr;
+	u16 read_off = 0;
+	struct hid_device *hdev = dev->hdev;
+
+	if (msgs[0].len > 2) {
+		hid_err(hdev, "%s: unsupported wr len: %d\n", __func__, len);
+		return -EOPNOTSUPP;
+	}
+
+	memcpy(&read_off, msgs[0].buf, msgs[0].len);
+
+	do {
+		if (left_len <= FT260_RD_DATA_MAX)
+			len = left_len;
+		else
+			len = FT260_RD_DATA_MAX;
+
+		ft260_dbg("read_off %#x left_len %d len %d\n", read_off,
+			  left_len, len);
+
+		ret = ft260_i2c_write(dev, addr, (u8 *)&read_off, msgs[0].len,
+				      FT260_FLAG_START);
+		if (ret < 0)
+			return ret;
+
+		ret = ft260_i2c_read(dev, addr, read_buf, len,
+				     FT260_FLAG_START_STOP);
+		if (ret < 0)
+			return ret;
+
+		left_len -= len;
+		read_buf += len;
+		read_off += len;
+
+	} while (left_len > 0);
+
+	return 0;
+}
+
+static int ft260_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
+			  int num)
+{
+	int ret;
+	struct ft260_device *dev = i2c_get_adapdata(adapter);
+	struct hid_device *hdev = dev->hdev;
+
+	mutex_lock(&dev->lock);
+
+	ret = hid_hw_power(hdev, PM_HINT_FULLON);
+	if (ret < 0) {
+		hid_err(hdev, "failed to enter FULLON power mode: %d\n", ret);
+		mutex_unlock(&dev->lock);
+		return ret;
+	}
+
+	if (num == 1) {
+		if (msgs->flags & I2C_M_RD)
+			ret = ft260_i2c_read(dev, msgs->addr, msgs->buf,
+					     msgs->len, FT260_FLAG_START_STOP);
+		else
+			ret = ft260_i2c_write(dev, msgs->addr, msgs->buf,
+					      msgs->len, FT260_FLAG_START_STOP);
+		if (ret < 0)
+			goto i2c_exit;
+
+	} else {
+		/* Combined write then read message */
+		ret = ft260_i2c_write_read(dev, msgs);
+		if (ret < 0)
+			goto i2c_exit;
+	}
+
+	ret = num;
+i2c_exit:
+	hid_hw_power(hdev, PM_HINT_NORMAL);
+	mutex_unlock(&dev->lock);
+	return ret;
+}
+
+static int ft260_smbus_xfer(struct i2c_adapter *adapter, u16 addr, u16 flags,
+			    char read_write, u8 cmd, int size,
+			    union i2c_smbus_data *data)
+{
+	int ret;
+	struct ft260_device *dev = i2c_get_adapdata(adapter);
+	struct hid_device *hdev = dev->hdev;
+
+	ft260_dbg("smbus size %d\n", size);
+
+	mutex_lock(&dev->lock);
+
+	ret = hid_hw_power(hdev, PM_HINT_FULLON);
+	if (ret < 0) {
+		hid_err(hdev, "power management error: %d\n", ret);
+		mutex_unlock(&dev->lock);
+		return ret;
+	}
+
+	switch (size) {
+	case I2C_SMBUS_QUICK:
+		if (read_write == I2C_SMBUS_READ)
+			ret = ft260_i2c_read(dev, addr, &data->byte, 0,
+					     FT260_FLAG_START_STOP);
+		else
+			ret = ft260_smbus_write(dev, addr, cmd, NULL, 0,
+						FT260_FLAG_START_STOP);
+		break;
+	case I2C_SMBUS_BYTE:
+		if (read_write == I2C_SMBUS_READ)
+			ret = ft260_i2c_read(dev, addr, &data->byte, 1,
+					     FT260_FLAG_START_STOP);
+		else
+			ret = ft260_smbus_write(dev, addr, cmd, NULL, 0,
+						FT260_FLAG_START_STOP);
+		break;
+	case I2C_SMBUS_BYTE_DATA:
+		if (read_write == I2C_SMBUS_READ) {
+			ret = ft260_smbus_write(dev, addr, cmd, NULL, 0,
+						FT260_FLAG_START);
+			if (ret)
+				goto smbus_exit;
+
+			ret = ft260_i2c_read(dev, addr, &data->byte, 1,
+					     FT260_FLAG_START_STOP_REPEATED);
+		} else {
+			ret = ft260_smbus_write(dev, addr, cmd, &data->byte, 1,
+						FT260_FLAG_START_STOP);
+		}
+		break;
+	case I2C_SMBUS_WORD_DATA:
+		if (read_write == I2C_SMBUS_READ) {
+			ret = ft260_smbus_write(dev, addr, cmd, NULL, 0,
+						FT260_FLAG_START);
+			if (ret)
+				goto smbus_exit;
+
+			ret = ft260_i2c_read(dev, addr, (u8 *)&data->word, 2,
+					     FT260_FLAG_START_STOP_REPEATED);
+		} else {
+			ret = ft260_smbus_write(dev, addr, cmd,
+						(u8 *)&data->word, 2,
+						FT260_FLAG_START_STOP);
+		}
+		break;
+	case I2C_SMBUS_BLOCK_DATA:
+		if (read_write == I2C_SMBUS_READ) {
+			ret = ft260_smbus_write(dev, addr, cmd, NULL, 0,
+						FT260_FLAG_START);
+			if (ret)
+				goto smbus_exit;
+
+			ret = ft260_i2c_read(dev, addr, data->block,
+					     data->block[0] + 1,
+					     FT260_FLAG_START_STOP_REPEATED);
+		} else {
+			ret = ft260_smbus_write(dev, addr, cmd, data->block,
+						data->block[0] + 1,
+						FT260_FLAG_START_STOP);
+		}
+		break;
+	case I2C_SMBUS_I2C_BLOCK_DATA:
+		if (read_write == I2C_SMBUS_READ) {
+			ret = ft260_smbus_write(dev, addr, cmd, NULL, 0,
+						FT260_FLAG_START);
+			if (ret)
+				goto smbus_exit;
+
+			ret = ft260_i2c_read(dev, addr, data->block + 1,
+					     data->block[0],
+					     FT260_FLAG_START_STOP_REPEATED);
+		} else {
+			ret = ft260_smbus_write(dev, addr, cmd, data->block + 1,
+						data->block[0],
+						FT260_FLAG_START_STOP);
+		}
+		break;
+	default:
+		hid_err(hdev, "unsupported smbus transaction size %d\n", size);
+		ret = -EOPNOTSUPP;
+	}
+
+smbus_exit:
+	hid_hw_power(hdev, PM_HINT_NORMAL);
+	mutex_unlock(&dev->lock);
+	return ret;
+}
+
+static u32 ft260_functionality(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_QUICK |
+	       I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
+	       I2C_FUNC_SMBUS_BLOCK_DATA | I2C_FUNC_SMBUS_I2C_BLOCK;
+}
+
+static const struct i2c_adapter_quirks ft260_i2c_quirks = {
+	.flags = I2C_AQ_COMB_WRITE_THEN_READ,
+	.max_comb_1st_msg_len = 2,
+};
+
+static const struct i2c_algorithm ft260_i2c_algo = {
+	.master_xfer = ft260_i2c_xfer,
+	.smbus_xfer = ft260_smbus_xfer,
+	.functionality = ft260_functionality,
+};
+
+static int ft260_get_system_config(struct hid_device *hdev,
+				   struct ft260_get_system_status_report *cfg)
+{
+	int ret;
+	int len = sizeof(struct ft260_get_system_status_report);
+
+	ret = ft260_hid_feature_report_get(hdev, FT260_SYSTEM_SETTINGS,
+					   (u8 *)cfg, len);
+	if (ret != len) {
+		hid_err(hdev, "failed to retrieve system status\n");
+		if (ret >= 0)
+			return -EIO;
+	}
+	return 0;
+}
+
+static int ft260_is_interface_enabled(struct hid_device *hdev)
+{
+	struct ft260_get_system_status_report cfg;
+	struct usb_interface *usbif = to_usb_interface(hdev->dev.parent);
+	int interface = usbif->cur_altsetting->desc.bInterfaceNumber;
+	int ret;
+
+	ret = ft260_get_system_config(hdev, &cfg);
+	if (ret)
+		return ret;
+
+	ft260_dbg("interface:  0x%02x\n", interface);
+	ft260_dbg("chip mode:  0x%02x\n", cfg.chip_mode);
+	ft260_dbg("clock_ctl:  0x%02x\n", cfg.clock_ctl);
+	ft260_dbg("i2c_enable: 0x%02x\n", cfg.i2c_enable);
+	ft260_dbg("uart_mode:  0x%02x\n", cfg.uart_mode);
+
+	switch (cfg.chip_mode) {
+	case FT260_MODE_ALL:
+	case FT260_MODE_BOTH:
+		if (interface == 1) {
+			hid_info(hdev, "uart interface is not supported\n");
+			return 0;
+		}
+		ret = 1;
+		break;
+	case FT260_MODE_UART:
+		if (interface == 0) {
+			hid_info(hdev, "uart is unsupported on interface 0\n");
+			ret = 0;
+		}
+		break;
+	case FT260_MODE_I2C:
+		if (interface == 1) {
+			hid_info(hdev, "i2c is unsupported on interface 1\n");
+			ret = 0;
+		}
+		break;
+	}
+	return ret;
+}
+
+static int ft260_byte_show(struct hid_device *hdev, int id, u8 *cfg, int len,
+			   u8 *field, u8 *buf)
+{
+	int ret;
+
+	ret = ft260_hid_feature_report_get(hdev, id, cfg, len);
+	if (ret != len && ret >= 0)
+		return -EIO;
+
+	return scnprintf(buf, PAGE_SIZE, "%hi\n", *field);
+}
+
+static int ft260_word_show(struct hid_device *hdev, int id, u8 *cfg, int len,
+			   u16 *field, u8 *buf)
+{
+	int ret;
+
+	ret = ft260_hid_feature_report_get(hdev, id, cfg, len);
+	if (ret != len && ret >= 0)
+		return -EIO;
+
+	return scnprintf(buf, PAGE_SIZE, "%hi\n", le16_to_cpu(*field));
+}
+
+#define FT260_ATTR_SHOW(name, reptype, id, type, func)			       \
+	static ssize_t name##_show(struct device *kdev,			       \
+				   struct device_attribute *attr, char *buf)   \
+	{								       \
+		struct reptype rep;					       \
+		struct hid_device *hdev = to_hid_device(kdev);		       \
+		type *field = &rep.name;				       \
+		int len = sizeof(rep);					       \
+									       \
+		return func(hdev, id, (u8 *)&rep, len, field, buf);	       \
+	}
+
+#define FT260_SSTAT_ATTR_SHOW(name)					       \
+		FT260_ATTR_SHOW(name, ft260_get_system_status_report,	       \
+				FT260_SYSTEM_SETTINGS, u8, ft260_byte_show)
+
+#define FT260_I2CST_ATTR_SHOW(name)					       \
+		FT260_ATTR_SHOW(name, ft260_get_i2c_status_report,	       \
+				FT260_I2C_STATUS, u16, ft260_word_show)
+
+#define FT260_ATTR_STORE(name, reptype, id, req, type, func)		       \
+	static ssize_t name##_store(struct device *kdev,		       \
+				    struct device_attribute *attr,	       \
+				    const char *buf, size_t count)	       \
+	{								       \
+		struct reptype rep;					       \
+		struct hid_device *hdev = to_hid_device(kdev);		       \
+		type name;						       \
+		int ret;						       \
+									       \
+		if (!func(buf, 10, &name)) {				       \
+			rep.name = name;				       \
+			rep.report = id;				       \
+			rep.request = req;				       \
+			ret = ft260_hid_feature_report_set(hdev, (u8 *)&rep,   \
+							   sizeof(rep));       \
+			if (!ret)					       \
+				ret = count;				       \
+		} else {						       \
+			ret = -EINVAL;					       \
+		}							       \
+		return ret;						       \
+	}
+
+#define FT260_BYTE_ATTR_STORE(name, reptype, req)			       \
+		FT260_ATTR_STORE(name, reptype, FT260_SYSTEM_SETTINGS, req,    \
+				 u8, kstrtou8)
+
+#define FT260_WORD_ATTR_STORE(name, reptype, req)			       \
+		FT260_ATTR_STORE(name, reptype, FT260_SYSTEM_SETTINGS, req,    \
+				 u16, kstrtou16)
+
+FT260_SSTAT_ATTR_SHOW(chip_mode);
+static DEVICE_ATTR_RO(chip_mode);
+
+FT260_SSTAT_ATTR_SHOW(pwren_status);
+static DEVICE_ATTR_RO(pwren_status);
+
+FT260_SSTAT_ATTR_SHOW(suspend_status);
+static DEVICE_ATTR_RO(suspend_status);
+
+FT260_SSTAT_ATTR_SHOW(hid_over_i2c_en);
+static DEVICE_ATTR_RO(hid_over_i2c_en);
+
+FT260_SSTAT_ATTR_SHOW(power_saving_en);
+static DEVICE_ATTR_RO(power_saving_en);
+
+FT260_SSTAT_ATTR_SHOW(i2c_enable);
+FT260_BYTE_ATTR_STORE(i2c_enable, ft260_set_i2c_mode_report,
+		      FT260_SET_I2C_MODE);
+static DEVICE_ATTR_RW(i2c_enable);
+
+FT260_SSTAT_ATTR_SHOW(uart_mode);
+FT260_BYTE_ATTR_STORE(uart_mode, ft260_set_uart_mode_report,
+		      FT260_SET_UART_MODE);
+static DEVICE_ATTR_RW(uart_mode);
+
+FT260_SSTAT_ATTR_SHOW(clock_ctl);
+FT260_BYTE_ATTR_STORE(clock_ctl, ft260_set_system_clock_report,
+		      FT260_SET_CLOCK);
+static DEVICE_ATTR_RW(clock_ctl);
+
+FT260_I2CST_ATTR_SHOW(clock);
+FT260_WORD_ATTR_STORE(clock, ft260_set_i2c_speed_report,
+		      FT260_SET_I2C_CLOCK_SPEED);
+static DEVICE_ATTR_RW(clock);
+
+static ssize_t i2c_reset_store(struct device *kdev,
+			       struct device_attribute *attr, const char *buf,
+			       size_t count)
+{
+	struct hid_device *hdev = to_hid_device(kdev);
+	int ret = ft260_i2c_reset(hdev);
+
+	if (ret)
+		return ret;
+	return count;
+}
+static DEVICE_ATTR_WO(i2c_reset);
+
+static const struct attribute_group ft260_attr_group = {
+	.attrs = (struct attribute *[]) {
+		  &dev_attr_chip_mode.attr,
+		  &dev_attr_pwren_status.attr,
+		  &dev_attr_suspend_status.attr,
+		  &dev_attr_hid_over_i2c_en.attr,
+		  &dev_attr_power_saving_en.attr,
+		  &dev_attr_i2c_enable.attr,
+		  &dev_attr_uart_mode.attr,
+		  &dev_attr_clock_ctl.attr,
+		  &dev_attr_i2c_reset.attr,
+		  &dev_attr_clock.attr,
+		  NULL
+	}
+};
+
+static int ft260_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	struct ft260_device *dev;
+	struct ft260_get_chip_version_report version;
+	int ret;
+
+	dev = devm_kzalloc(&hdev->dev, sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "failed to parse HID\n");
+		return ret;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
+	if (ret) {
+		hid_err(hdev, "failed to start HID HW\n");
+		return ret;
+	}
+
+	ret = hid_hw_open(hdev);
+	if (ret) {
+		hid_err(hdev, "failed to open HID HW\n");
+		goto err_hid_stop;
+	}
+
+	ret = ft260_hid_feature_report_get(hdev, FT260_CHIP_VERSION,
+					   (u8 *)&version, sizeof(version));
+	if (ret != sizeof(version)) {
+		hid_err(hdev, "failed to retrieve chip version\n");
+		if (ret >= 0)
+			ret = -EIO;
+		goto err_hid_close;
+	}
+
+	hid_info(hdev, "chip code: %02x%02x %02x%02x\n",
+		 version.chip_code[0], version.chip_code[1],
+		 version.chip_code[2], version.chip_code[3]);
+
+	ret = ft260_is_interface_enabled(hdev);
+	if (ret <= 0)
+		goto err_hid_close;
+
+	hid_set_drvdata(hdev, dev);
+	dev->hdev = hdev;
+	dev->adap.owner = THIS_MODULE;
+	dev->adap.class = I2C_CLASS_HWMON;
+	dev->adap.algo = &ft260_i2c_algo;
+	dev->adap.quirks = &ft260_i2c_quirks;
+	dev->adap.dev.parent = &hdev->dev;
+	snprintf(dev->adap.name, sizeof(dev->adap.name),
+		 "FT260 usb-i2c bridge on hidraw%d",
+		 ((struct hidraw *)hdev->hidraw)->minor);
+
+	mutex_init(&dev->lock);
+	init_completion(&dev->wait);
+
+	ret = i2c_add_adapter(&dev->adap);
+	if (ret) {
+		hid_err(hdev, "failed to add i2c adapter\n");
+		goto err_hid_close;
+	}
+
+	i2c_set_adapdata(&dev->adap, dev);
+
+	ret = sysfs_create_group(&hdev->dev.kobj, &ft260_attr_group);
+	if (ret < 0) {
+		hid_err(hdev, "failed to create sysfs attrs\n");
+		goto err_i2c_free;
+	}
+
+	ret = ft260_xfer_status(dev);
+	if (ret)
+		ft260_i2c_reset(hdev);
+
+	return 0;
+
+err_i2c_free:
+	i2c_del_adapter(&dev->adap);
+err_hid_close:
+	hid_hw_close(hdev);
+err_hid_stop:
+	hid_hw_stop(hdev);
+	return ret;
+}
+
+static void ft260_remove(struct hid_device *hdev)
+{
+	int ret;
+	struct ft260_device *dev = hid_get_drvdata(hdev);
+
+	ret = ft260_is_interface_enabled(hdev);
+	if (ret <= 0)
+		return;
+
+	sysfs_remove_group(&hdev->dev.kobj, &ft260_attr_group);
+	i2c_del_adapter(&dev->adap);
+
+	hid_hw_close(hdev);
+	hid_hw_stop(hdev);
+}
+
+static int ft260_raw_event(struct hid_device *hdev, struct hid_report *report,
+			   u8 *data, int size)
+{
+	struct ft260_device *dev = hid_get_drvdata(hdev);
+	struct ft260_i2c_input_report *xfer = (void *)data;
+
+	if (xfer->report >= FT260_I2C_REPORT_MIN &&
+	    xfer->report <= FT260_I2C_REPORT_MAX) {
+		ft260_dbg("i2c resp: rep %#02x len %d\n", xfer->report,
+			  xfer->length);
+
+		memcpy(&dev->read_buf[dev->read_idx], &xfer->data,
+		       xfer->length);
+		dev->read_idx += xfer->length;
+
+		if (dev->read_idx == dev->read_len)
+			complete(&dev->wait);
+
+	} else {
+		hid_err(hdev, "unknown report: %#02x\n", xfer->report);
+		return 0;
+	}
+	return 1;
+}
+
+static struct hid_driver ft260_driver = {
+	.name		= "ft260",
+	.id_table	= ft260_devices,
+	.probe		= ft260_probe,
+	.remove		= ft260_remove,
+	.raw_event	= ft260_raw_event,
+};
+
+module_hid_driver(ft260_driver);
+MODULE_DESCRIPTION("FTDI FT260 USB HID to I2C host bridge");
+MODULE_AUTHOR("Michael Zaidman <michael.zaidman@gmail.com>");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index e42aaae3138f..daa4c0318cbc 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -430,6 +430,7 @@
 
 #define USB_VENDOR_ID_FUTURE_TECHNOLOGY	0x0403
 #define USB_DEVICE_ID_RETRODE2		0x97c1
+#define USB_DEVICE_ID_FT260             0x6030
 
 #define USB_VENDOR_ID_ESSENTIAL_REALITY	0x0d7f
 #define USB_DEVICE_ID_ESSENTIAL_REALITY_P5 0x0100
-- 
2.25.1