[PATCH 2/2] USB: misc: Add driver for the WCH CH341 in I2C/GPIO mode
From: Frank Zago
Date: Mon Apr 19 2021 - 22:25:42 EST
From: frank zago <frank@xxxxxxxx>
The CH341 is a multifunction chip, presenting 3 different USB PID. One
of these functions is for I2C/SPI/GPIO. This new driver manages I2C
and GPIO. A future update will manage the SPI part as well.
The I2C interface can run at 4 different speeds. This driver currently
only offer 100MHz. Tested with a variety of I2C sensors, and the IIO
subsystem.
The GPIO interface offers 8 GPIOs. 6 are read/write, and 2 are
rea-only. However the SPI interface will use 6 of them, leaving 2
available GPIOs.
Signed-off-by: Frank Zago <frank@xxxxxxxx>
Signed-off-by: frank zago <frank@xxxxxxxx>
---
MAINTAINERS | 6 +
drivers/usb/misc/Kconfig | 18 ++
drivers/usb/misc/Makefile | 1 +
drivers/usb/misc/ch341/Kconfig | 0
drivers/usb/misc/ch341/Makefile | 3 +
drivers/usb/misc/ch341/ch341-core.c | 87 +++++++++
drivers/usb/misc/ch341/ch341-gpio.c | 249 ++++++++++++++++++++++++++
drivers/usb/misc/ch341/ch341-i2c.c | 267 ++++++++++++++++++++++++++++
drivers/usb/misc/ch341/ch341.h | 50 ++++++
9 files changed, 681 insertions(+)
create mode 100644 drivers/usb/misc/ch341/Kconfig
create mode 100644 drivers/usb/misc/ch341/Makefile
create mode 100644 drivers/usb/misc/ch341/ch341-core.c
create mode 100644 drivers/usb/misc/ch341/ch341-gpio.c
create mode 100644 drivers/usb/misc/ch341/ch341-i2c.c
create mode 100644 drivers/usb/misc/ch341/ch341.h
diff --git a/MAINTAINERS b/MAINTAINERS
index 95e6766718b0..17e3d03cf9bf 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19349,6 +19349,12 @@ M: David Härdeman <david@xxxxxxxxxxx>
S: Maintained
F: drivers/media/rc/winbond-cir.c
+WINCHIPHEAD CH341 I2C/GPIO/SPI DRIVER
+M: Frank Zago <frank@xxxxxxxx>
+L: linux-usb@xxxxxxxxxxxxxxx
+S: Maintained
+F: drivers/usb/misc/ch341/
+
WINSYSTEMS EBC-C384 WATCHDOG DRIVER
M: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
L: linux-watchdog@xxxxxxxxxxxxxxx
diff --git a/drivers/usb/misc/Kconfig b/drivers/usb/misc/Kconfig
index 8f1144359012..2d4db92f0de4 100644
--- a/drivers/usb/misc/Kconfig
+++ b/drivers/usb/misc/Kconfig
@@ -284,3 +284,21 @@ config BRCM_USB_PINMAP
This option enables support for remapping some USB external
signals, which are typically on dedicated pins on the chip,
to any gpio.
+
+config USB_CH341_CORE
+ tristate "USB WinChipHead CH341 in I2C/SPI/GPIO mode"
+ depends on USB && GPIOLIB && I2C && SPI
+ help
+
+ If you say yes to this option, support for the CH341 chips,
+ running in I2C/SPI/GPIO mode will be included. Some versions
+ of the chip do not support all the functionnalities but
+ there is no way to differentiate them. For instance the
+ CH341A and CH341B support everything while the CH341T can
+ only do I2C.
+
+ The serial mode is not supported by this driver. Use the
+ CH341 USB serial driver.
+
+ This driver can also be built as a module. If so, the
+ module will be called ch341-buses.
diff --git a/drivers/usb/misc/Makefile b/drivers/usb/misc/Makefile
index 5f4e598573ab..95c0ca15b8c9 100644
--- a/drivers/usb/misc/Makefile
+++ b/drivers/usb/misc/Makefile
@@ -32,3 +32,4 @@ obj-$(CONFIG_USB_CHAOSKEY) += chaoskey.o
obj-$(CONFIG_USB_SISUSBVGA) += sisusbvga/
obj-$(CONFIG_USB_LINK_LAYER_TEST) += lvstest.o
obj-$(CONFIG_BRCM_USB_PINMAP) += brcmstb-usb-pinmap.o
+obj-$(CONFIG_USB_CH341_CORE) += ch341/
diff --git a/drivers/usb/misc/ch341/Kconfig b/drivers/usb/misc/ch341/Kconfig
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/drivers/usb/misc/ch341/Makefile b/drivers/usb/misc/ch341/Makefile
new file mode 100644
index 000000000000..7c6429e7a46e
--- /dev/null
+++ b/drivers/usb/misc/ch341/Makefile
@@ -0,0 +1,3 @@
+obj-$(CONFIG_USB_CH341_CORE) := ch341-buses.o
+
+ch341-buses-objs := ch341-core.o ch341-i2c.o ch341-gpio.o
diff --git a/drivers/usb/misc/ch341/ch341-core.c b/drivers/usb/misc/ch341/ch341-core.c
new file mode 100644
index 000000000000..19c531715ea3
--- /dev/null
+++ b/drivers/usb/misc/ch341/ch341-core.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for the CH341A, and CH341B USB to I2C/GPIO adapter
+ * Driver for the CH341T USB to I2C adapter
+ *
+ * Copyright 2021, Frank Zago
+ * Copyright (c) 2017 Gunar Schorcht (gunar@xxxxxxxxxxxx)
+ * Copyright (c) 2016 Tse Lun Bien
+ * Copyright (c) 2014 Marco Gittler
+ * Copyright (c) 2006-2007 Till Harbaum (Till@xxxxxxxxxxx)
+ *
+ * The full UART functionality is handled by the CH341 serial driver
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include "ch341.h"
+
+static void ch341_usb_free_device(struct ch341_device *dev)
+{
+ ch341_gpio_remove(dev);
+ ch341_i2c_remove(dev);
+
+ usb_set_intfdata(dev->iface, NULL);
+ usb_put_dev(dev->usb_dev);
+
+ kfree(dev);
+}
+
+static int ch341_usb_probe(struct usb_interface *iface,
+ const struct usb_device_id *usb_id)
+{
+ struct ch341_device *dev;
+ int error;
+
+ dev = kzalloc(sizeof(struct ch341_device), GFP_KERNEL);
+ if (!dev)
+ return -ENOMEM;
+
+ dev->usb_dev = usb_get_dev(interface_to_usbdev(iface));
+ dev->iface = iface;
+ mutex_init(&dev->usb_lock);
+ dev->ep_out = iface->cur_altsetting->endpoint[1].desc.bEndpointAddress;
+ dev->ep_in = iface->cur_altsetting->endpoint[0].desc.bEndpointAddress;
+
+ usb_set_intfdata(iface, dev);
+
+ error = ch341_i2c_init(dev);
+ if (error) {
+ ch341_usb_free_device(dev);
+ return error;
+ }
+
+ error = ch341_gpio_init(dev);
+ if (error) {
+ ch341_usb_free_device(dev);
+ return error;
+ }
+
+ return 0;
+}
+
+static void ch341_usb_disconnect(struct usb_interface *usb_if)
+{
+ struct ch341_device *dev = usb_get_intfdata(usb_if);
+
+ ch341_usb_free_device(dev);
+}
+
+static const struct usb_device_id ch341_usb_table[] = {
+ { USB_DEVICE(0x1a86, 0x5512) },
+ { }
+};
+
+static struct usb_driver ch341_usb_driver = {
+ .name = "ch341-buses",
+ .id_table = ch341_usb_table,
+ .probe = ch341_usb_probe,
+ .disconnect = ch341_usb_disconnect
+};
+
+module_usb_driver(ch341_usb_driver);
+
+MODULE_AUTHOR("Various");
+MODULE_DESCRIPTION("ch341 USB to I2C/GPIO adapter");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/usb/misc/ch341/ch341-gpio.c b/drivers/usb/misc/ch341/ch341-gpio.c
new file mode 100644
index 000000000000..fff983be6c6c
--- /dev/null
+++ b/drivers/usb/misc/ch341/ch341-gpio.c
@@ -0,0 +1,249 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * GPIO interface for the CH341A and CH341B chips.
+ *
+ * Copyright 2021, Frank Zago
+ * Copyright (c) 2017 Gunar Schorcht (gunar@xxxxxxxxxxxx)
+ * Copyright (c) 2016 Tse Lun Bien
+ * Copyright (c) 2014 Marco Gittler
+ * Copyright (c) 2006-2007 Till Harbaum (Till@xxxxxxxxxxx)
+ */
+
+/* Notes.
+ *
+ * For the CH341, 0=IN, 1=OUT, but for the GPIO subsystem, 1=IN and
+ * 0=OUT. Some translation happens in a couple places.
+ */
+
+#include "ch341.h"
+
+#define CH341_GPIO_NUM_PINS 8 /* Number of GPIO pins */
+
+#define CH341_CMD_UIO_STREAM 0xAB /* UIO stream command */
+
+#define CH341_CMD_UIO_STM_IN 0x00 /* UIO interface IN command (D0~D7) */
+#define CH341_CMD_UIO_STM_OUT 0x80 /* UIO interface OUT command (D0~D5) */
+#define CH341_CMD_UIO_STM_DIR 0x40 /* UIO interface DIR command (D0~D5) */
+#define CH341_CMD_UIO_STM_END 0x20 /* UIO interface END command */
+
+/* Masks to describe the 8 GPIOs (pins 15 to 22, a.k.a. D0 to D7.)
+ * D0 to D5 can read/write, but pins D6 and D7 can only read.
+ */
+static const u8 pin_can_output = 0b00111111;
+
+/* Various names appearing on breakout boards. */
+static const char * const gpio_names[CH341_GPIO_NUM_PINS] = {
+ "D0/CS0",
+ "D1/CS1",
+ "D2/CS2",
+ "D3/SCK/DCK",
+ "D4/DOUT2",
+ "D5/MOSI/DOUT/SDO",
+ "D6/DIN2",
+ "D7/MISO/DIN"
+};
+
+static void ch341_gpio_dbg_show(struct seq_file *s, struct gpio_chip *chip)
+{
+ struct ch341_device *dev = gpiochip_get_data(chip);
+
+ seq_printf(s, "pin config : %02x (0=IN, 1=OUT)\n", dev->gpio_dir);
+ seq_printf(s, "last read : %02x\n", dev->gpio_last_read);
+ seq_printf(s, "last written: %02x\n", dev->gpio_last_written);
+}
+
+/* Send a command and get a reply if requested */
+static int gpio_transfer(struct ch341_device *dev, int out_len, int in_len)
+{
+ int actual;
+ int rc;
+
+ mutex_lock(&dev->usb_lock);
+
+ rc = usb_bulk_msg(dev->usb_dev,
+ usb_sndbulkpipe(dev->usb_dev, dev->ep_out),
+ dev->gpio_buf, out_len,
+ &actual, DEFAULT_TIMEOUT);
+ if (rc < 0)
+ goto done;
+
+ if (in_len == 0) {
+ rc = actual;
+ goto done;
+ }
+
+ rc = usb_bulk_msg(dev->usb_dev,
+ usb_rcvbulkpipe(dev->usb_dev, dev->ep_in),
+ dev->gpio_buf, PKT_SIZE, &actual, DEFAULT_TIMEOUT);
+
+ if (rc == 0)
+ rc = actual;
+
+done:
+ mutex_unlock(&dev->usb_lock);
+
+ return rc;
+}
+
+static int read_inputs(struct ch341_device *dev)
+{
+ int result;
+
+ mutex_lock(&dev->gpio_lock);
+
+ dev->gpio_buf[0] = CH341_CMD_UIO_STREAM;
+ dev->gpio_buf[1] = CH341_CMD_UIO_STM_DIR | dev->gpio_dir;
+ dev->gpio_buf[2] = CH341_CMD_UIO_STM_IN;
+ dev->gpio_buf[3] = CH341_CMD_UIO_STM_END;
+
+ result = gpio_transfer(dev, 4, 1);
+
+ if (result == 1)
+ dev->gpio_last_read = dev->gpio_buf[0];
+
+ mutex_unlock(&dev->gpio_lock);
+
+ return (result != 1) ? result : 0;
+}
+
+static int ch341_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+ struct ch341_device *dev = gpiochip_get_data(chip);
+ int rc;
+
+ rc = read_inputs(dev);
+ if (rc)
+ return rc;
+
+ return (dev->gpio_last_read & BIT(offset)) ? 1 : 0;
+}
+
+static int ch341_gpio_get_multiple(struct gpio_chip *chip,
+ unsigned long *mask, unsigned long *bits)
+{
+ struct ch341_device *dev = gpiochip_get_data(chip);
+ int rc;
+
+ rc = read_inputs(dev);
+ if (rc)
+ return rc;
+
+ *bits = dev->gpio_last_read & *mask;
+
+ return 0;
+}
+
+static void write_outputs(struct ch341_device *dev)
+{
+ mutex_lock(&dev->gpio_lock);
+
+ dev->gpio_buf[0] = CH341_CMD_UIO_STREAM;
+ dev->gpio_buf[1] = CH341_CMD_UIO_STM_DIR | dev->gpio_dir;
+ dev->gpio_buf[2] = CH341_CMD_UIO_STM_OUT | (dev->gpio_last_written & dev->gpio_dir);
+ dev->gpio_buf[3] = CH341_CMD_UIO_STM_END;
+
+ gpio_transfer(dev, 4, 0);
+
+ mutex_unlock(&dev->gpio_lock);
+}
+
+static void ch341_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
+{
+ struct ch341_device *dev = gpiochip_get_data(chip);
+
+ if (value)
+ dev->gpio_last_written |= BIT(offset);
+ else
+ dev->gpio_last_written &= ~BIT(offset);
+
+ write_outputs(dev);
+}
+
+static void ch341_gpio_set_multiple(struct gpio_chip *chip,
+ unsigned long *mask, unsigned long *bits)
+{
+ struct ch341_device *dev = gpiochip_get_data(chip);
+
+ dev->gpio_last_written &= ~*mask;
+ dev->gpio_last_written |= (*bits & *mask);
+
+ write_outputs(dev);
+}
+
+static int ch341_gpio_get_direction(struct gpio_chip *chip,
+ unsigned int offset)
+{
+ struct ch341_device *dev = gpiochip_get_data(chip);
+
+ return (dev->gpio_dir & BIT(offset)) ? 0 : 1;
+}
+
+static int ch341_gpio_direction_input(struct gpio_chip *chip,
+ unsigned int offset)
+{
+ struct ch341_device *dev = gpiochip_get_data(chip);
+
+ dev->gpio_dir &= ~BIT(offset);
+
+ return 0;
+}
+
+static int ch341_gpio_direction_output(struct gpio_chip *chip,
+ unsigned int offset, int value)
+{
+ struct ch341_device *dev = gpiochip_get_data(chip);
+ u8 mask = BIT(offset);
+
+ if (!(pin_can_output & mask))
+ return -EINVAL;
+
+ dev->gpio_dir |= mask;
+
+ ch341_gpio_set(chip, offset, value);
+
+ return 0;
+}
+
+void ch341_gpio_remove(struct ch341_device *dev)
+{
+ if (!dev->gpio_init)
+ return;
+
+ gpiochip_remove(&dev->gpio);
+}
+
+int ch341_gpio_init(struct ch341_device *dev)
+{
+ struct gpio_chip *gpio = &dev->gpio;
+ int result;
+
+ gpio->label = "ch341";
+ gpio->parent = &dev->usb_dev->dev;
+ gpio->owner = THIS_MODULE;
+ gpio->get_direction = ch341_gpio_get_direction;
+ gpio->direction_input = ch341_gpio_direction_input;
+ gpio->direction_output = ch341_gpio_direction_output;
+ gpio->get = ch341_gpio_get;
+ gpio->get_multiple = ch341_gpio_get_multiple;
+ gpio->set = ch341_gpio_set;
+ gpio->set_multiple = ch341_gpio_set_multiple;
+ gpio->dbg_show = ch341_gpio_dbg_show;
+ gpio->base = -1;
+ gpio->ngpio = CH341_GPIO_NUM_PINS;
+ gpio->names = gpio_names;
+ gpio->can_sleep = true;
+
+ dev->gpio_dir = 0; /* All pins as input */
+
+ mutex_init(&dev->gpio_lock);
+
+ result = gpiochip_add_data(gpio, dev);
+ if (result) {
+ dev_err(&dev->usb_dev->dev, "Could not add GPIO\n");
+ return result;
+ }
+
+ dev->gpio_init = true;
+
+ return 0;
+}
diff --git a/drivers/usb/misc/ch341/ch341-i2c.c b/drivers/usb/misc/ch341/ch341-i2c.c
new file mode 100644
index 000000000000..be675dc54166
--- /dev/null
+++ b/drivers/usb/misc/ch341/ch341-i2c.c
@@ -0,0 +1,267 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * I2C interface for the CH341A, CH341B and CH341T.
+ *
+ * Copyright 2021, Frank Zago
+ * Copyright (c) 2016 Tse Lun Bien
+ * Copyright (c) 2014 Marco Gittler
+ * Copyright (C) 2006-2007 Till Harbaum (Till@xxxxxxxxxxx)
+ */
+
+#include "ch341.h"
+
+/* Support not yet implemented */
+#define CH341_I2C_LOW_SPEED 0 /* 20kHz */
+#define CH341_I2C_STANDARD_SPEED 1 /* 100kHz */
+#define CH341_I2C_FAST_SPEED 2 /* 400kHz */
+#define CH341_I2C_HIGH_SPEED 3 /* 750kHz */
+
+#define CH341_CMD_I2C_STREAM 0xAA
+#define CH341_CMD_I2C_STM_END 0x00
+
+#define CH341_CMD_I2C_STM_STA 0x74
+#define CH341_CMD_I2C_STM_STO 0x75
+#define CH341_CMD_I2C_STM_OUT 0x80
+#define CH341_CMD_I2C_STM_IN 0xC0
+#define CH341_CMD_I2C_STM_SET 0x60
+#define CH341_CMD_I2C_STM_MS 0x50
+
+#define CH341_CTRL_VENDOR_VERSION 0x5F /* version of chip */
+#define CH341_CTRL_VENDOR_READ_TYPE 0XC0 /* vendor control read */
+
+/* Append a write command to the current request */
+static int append_write(struct ch341_device *dev, const struct i2c_msg *msg)
+{
+ u8 *out = dev->i2c_buf;
+ int len;
+ u8 *p;
+ bool start_done = false;
+
+ len = msg->len;
+ p = msg->buf;
+
+ while (len) {
+ int to_write;
+ int avail;
+
+ if (dev->idx_out % PKT_SIZE) {
+ /* Finish current packet, and advance to the next one */
+ out[dev->idx_out++] = CH341_CMD_I2C_STM_END;
+ dev->out_pkt++;
+ dev->idx_out = dev->out_pkt * PKT_SIZE;
+
+ if (dev->out_pkt == PKT_COUNT)
+ return -E2BIG;
+ }
+
+ out[dev->idx_out++] = CH341_CMD_I2C_STREAM;
+
+ /* account for stream start and end, STA and possible STO */
+ avail = PKT_SIZE - 4;
+
+ if (!start_done) {
+ /* Each message has a start */
+ out[dev->idx_out++] = CH341_CMD_I2C_STM_STA;
+
+ avail -= 2; /* room for STA and device address */
+ }
+
+ to_write = min_t(int, len, avail);
+
+ if (!start_done) {
+ out[dev->idx_out++] = CH341_CMD_I2C_STM_OUT | (to_write + 1);
+ out[dev->idx_out++] = msg->addr << 1;
+
+ start_done = true;
+ } else {
+ out[dev->idx_out++] = CH341_CMD_I2C_STM_OUT | to_write;
+ }
+
+ memcpy(&out[dev->idx_out], p, to_write);
+ dev->idx_out += to_write;
+ len -= to_write;
+ }
+
+ return 0;
+}
+
+/* Append a read command to the request. It usually follows a write
+ * command. When that happens, the driver will attempt to concat the
+ * read command into the same packet. This is necessary for eeprom
+ * devices, otherwise the full request would go past 128 bytes, which
+ * the adapter doesn't support.
+ */
+static int append_read(struct ch341_device *dev, const struct i2c_msg *msg)
+{
+ u8 *out = dev->i2c_buf;
+ bool start_done = false;
+ int len;
+
+ len = msg->len;
+
+ while (len) {
+ int to_read;
+
+ if (dev->idx_out % PKT_SIZE) {
+ if (!start_done &&
+ (dev->idx_out % PKT_SIZE) < (PKT_SIZE - 7)) {
+ /* There's enough left for a read */
+ } else {
+ /* Finish current packet, and advance to the next one */
+ out[dev->idx_out++] = CH341_CMD_I2C_STM_END;
+ dev->out_pkt++;
+ dev->idx_out = dev->out_pkt * PKT_SIZE;
+
+ if (dev->out_pkt == PKT_COUNT)
+ return -E2BIG;
+
+ out[dev->idx_out++] = CH341_CMD_I2C_STREAM;
+ }
+ } else {
+ out[dev->idx_out++] = CH341_CMD_I2C_STREAM;
+ }
+
+ if (!start_done) {
+ /* Each message has a start */
+ out[dev->idx_out++] = CH341_CMD_I2C_STM_STA;
+ out[dev->idx_out++] = CH341_CMD_I2C_STM_OUT | 1;
+ out[dev->idx_out++] = msg->addr << 1 | 1;
+
+ start_done = true;
+ }
+
+ /* Apparently the last command must be an STM_IN to
+ * read the last byte. Without it, the adapter gets
+ * lost.
+ */
+ to_read = min_t(int, len, 32);
+ len -= to_read;
+ if (len == 0) {
+ if (to_read > 1)
+ out[dev->idx_out++] = CH341_CMD_I2C_STM_IN | (to_read - 1);
+ out[dev->idx_out++] = CH341_CMD_I2C_STM_IN;
+ } else {
+ out[dev->idx_out++] = CH341_CMD_I2C_STM_IN | to_read;
+ }
+ }
+
+ return 0;
+}
+
+static int ch341_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
+{
+ struct ch341_device *dev = adapter->algo_data;
+ int retval;
+ int i;
+ u8 *out = dev->i2c_buf;
+ int actual;
+
+ /* Prepare the request */
+ dev->idx_out = 0;
+ dev->out_pkt = 0;
+
+ for (i = 0; i != num; i++) {
+ if (msgs[i].flags & I2C_M_RD)
+ retval = append_read(dev, &msgs[i]);
+ else
+ retval = append_write(dev, &msgs[i]);
+
+ if (retval)
+ return retval;
+ }
+
+ out[dev->idx_out++] = CH341_CMD_I2C_STM_STO;
+ out[dev->idx_out++] = CH341_CMD_I2C_STM_END;
+
+ dev_dbg(&dev->adapter.dev, "bulk_out request with %d bytes\n",
+ dev->idx_out);
+
+ mutex_lock(&dev->usb_lock);
+
+ /* Issue the request */
+ retval = usb_bulk_msg(dev->usb_dev,
+ usb_sndbulkpipe(dev->usb_dev, dev->ep_out),
+ dev->i2c_buf, dev->idx_out, &actual, DEFAULT_TIMEOUT);
+ if (retval < 0) {
+ mutex_unlock(&dev->usb_lock);
+ return retval;
+ }
+
+ for (i = 0; i != num; i++) {
+ if (!(msgs[i].flags & I2C_M_RD))
+ continue;
+
+ retval = usb_bulk_msg(dev->usb_dev,
+ usb_rcvbulkpipe(dev->usb_dev, dev->ep_in),
+ dev->i2c_buf, msgs[i].len, &actual, DEFAULT_TIMEOUT);
+
+ if (retval) {
+ mutex_lock(&dev->usb_lock);
+ return retval;
+ }
+
+ if (actual != msgs[i].len) {
+ mutex_lock(&dev->usb_lock);
+ return -EIO;
+ }
+
+ memcpy(msgs[i].buf, dev->i2c_buf, actual);
+ }
+
+ mutex_unlock(&dev->usb_lock);
+
+ return num;
+}
+
+static u32 ch341_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm ch341_i2c_algorithm = {
+ .master_xfer = ch341_i2c_xfer,
+ .functionality = ch341_i2c_func,
+};
+
+void ch341_i2c_remove(struct ch341_device *dev)
+{
+ if (!dev->i2c_init)
+ return;
+
+ i2c_del_adapter(&dev->adapter);
+}
+
+int ch341_i2c_init(struct ch341_device *dev)
+{
+ int retval;
+ int actual;
+
+ dev->adapter.owner = THIS_MODULE;
+ dev->adapter.class = I2C_CLASS_HWMON;
+ dev->adapter.algo = &ch341_i2c_algorithm;
+ dev->adapter.algo_data = dev;
+ snprintf(dev->adapter.name, sizeof(dev->adapter.name),
+ "CH341 I2C USB bus %03d device %03d",
+ dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
+
+ dev->adapter.dev.parent = &dev->iface->dev;
+
+ /* Set ch341 i2c speed */
+ dev->i2c_buf[0] = CH341_CMD_I2C_STREAM;
+ dev->i2c_buf[1] = CH341_CMD_I2C_STM_SET | CH341_I2C_STANDARD_SPEED;
+ dev->i2c_buf[2] = CH341_CMD_I2C_STM_END;
+ mutex_lock(&dev->usb_lock);
+ retval = usb_bulk_msg(dev->usb_dev,
+ usb_sndbulkpipe(dev->usb_dev, dev->ep_out),
+ dev->i2c_buf, 3, &actual, DEFAULT_TIMEOUT);
+ mutex_unlock(&dev->usb_lock);
+ if (retval < 0) {
+ dev_err(&dev->adapter.dev, "Cannot set I2C speed\n");
+ return -EIO;
+ }
+
+ i2c_add_adapter(&dev->adapter);
+ dev->i2c_init = true;
+
+ return 0;
+}
diff --git a/drivers/usb/misc/ch341/ch341.h b/drivers/usb/misc/ch341/ch341.h
new file mode 100644
index 000000000000..4ddd77c2e08c
--- /dev/null
+++ b/drivers/usb/misc/ch341/ch341.h
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Definitions for CH341 driver
+ */
+
+#include <linux/usb.h>
+#include <linux/i2c.h>
+#include <linux/gpio.h>
+
+#define DEFAULT_TIMEOUT 1000 /* 1s USB requests timeout */
+
+/* I2C - The maximum request size is 128 bytes, for reading and
+ * writing. The adapter will get the buffer in packets of up to 32
+ * bytes. The I2C stream must start and stop in each 32-byte packet.
+ * Reading must also be split, up to 32-byte per packet.
+ */
+#define PKT_SIZE 32
+#define PKT_COUNT 4
+
+struct ch341_device {
+ struct usb_device *usb_dev;
+ struct usb_interface *iface;
+ struct mutex usb_lock;
+
+ int ep_in;
+ int ep_out;
+
+ /* I2C */
+ struct i2c_adapter adapter;
+ bool i2c_init;
+
+ /* I2C request and response state */
+ int idx_out; /* current offset in buf */
+ int out_pkt; /* current packet */
+ u8 i2c_buf[PKT_COUNT * PKT_SIZE];
+
+ /* GPIO */
+ struct gpio_chip gpio;
+ struct mutex gpio_lock;
+ bool gpio_init;
+ u8 gpio_dir; /* 1 bit per pin, 0=IN, 1=OUT. */
+ u8 gpio_last_read; /* last GPIO values read */
+ u8 gpio_last_written; /* last GPIO values written */
+ u8 gpio_buf[PKT_SIZE];
+};
+
+void ch341_i2c_remove(struct ch341_device *dev);
+int ch341_i2c_init(struct ch341_device *dev);
+void ch341_gpio_remove(struct ch341_device *dev);
+int ch341_gpio_init(struct ch341_device *dev);
--
2.27.0