[PATCH v6 0/4] add driver for the WCH CH341 in I2C/GPIO mode

[PATCH v6 0/4] add driver for the WCH CH341 in I2C/GPIO mode

[frank zago]

The CH341 is a multifunction chip, presenting 3 different USB PID. One
of these functions is for I2C/SPI/GPIO. This new set of drivers will
manage I2C and GPIO.

Changes from v5:
Addressed reviewers' comments.
Better handling of 0-bytes i2c commands
Use of better USB API.

Changes from v4:
I should have addressed all the comments: rework of the GPIO interrupt
handling code to be more modern, changes in Kconfig wording, some code
cleanup.
Driver was tested again with up to 4 of these devices. No
error seen.

Changes from v3:
  - really converted to an MFD driver. Driver is now split into 3
    modules (MFD+I2C+GPIO).
  - minor code cleanups

Changes from v2:
  - bug fixes
  - more robust USB enumeration
  - Changed to an MFD driver as suggested

During testing I found that i2c handles hot removal, but not gpio. The
gpio subsystem will complain with 'REMOVING GPIOCHIP WITH GPIOS STILL
REQUESTED', but it's a gpiolib issue.

Changes from v1:
  - Removed double Signed-off-by
  - Move Kconfig into the same directory as the driver

frank zago (4):
  mfd: ch341: add core driver for the WCH CH341 in I2C/SPI/GPIO mode
  gpio: ch341: add GPIO MFD cell driver for the CH341
  i2c: ch341: add I2C MFD cell driver for the CH341
  docs: misc: add documentation for ch341 driver

 Documentation/misc-devices/ch341.rst | 109 ++++++++
 Documentation/misc-devices/index.rst |   1 +
 MAINTAINERS                          |   9 +
 drivers/gpio/Kconfig                 |  10 +
 drivers/gpio/Makefile                |   1 +
 drivers/gpio/gpio-ch341.c            | 385 +++++++++++++++++++++++++++
 drivers/i2c/busses/Kconfig           |  10 +
 drivers/i2c/busses/Makefile          |   1 +
 drivers/i2c/busses/i2c-ch341.c       | 377 ++++++++++++++++++++++++++
 drivers/mfd/Kconfig                  |  10 +
 drivers/mfd/Makefile                 |   1 +
 drivers/mfd/ch341-core.c             |  90 +++++++
 include/linux/mfd/ch341.h            |  26 ++
 13 files changed, 1030 insertions(+)
 create mode 100644 Documentation/misc-devices/ch341.rst
 create mode 100644 drivers/gpio/gpio-ch341.c
 create mode 100644 drivers/i2c/busses/i2c-ch341.c
 create mode 100644 drivers/mfd/ch341-core.c
 create mode 100644 include/linux/mfd/ch341.h

--
2.32.0

[PATCH v6 1/4] mfd: ch341: add core driver for the WCH CH341 in I2C/SPI/GPIO mode

[frank zago]

The CH341 is a multifunction chip, presenting 3 different USB PID. One
of these functions is for I2C/SPI/GPIO. This new set of drivers will
manage I2C and GPIO.

Signed-off-by: frank zago <frank@zago.net>
---
 MAINTAINERS               |  7 +++
 drivers/mfd/Kconfig       | 10 +++++
 drivers/mfd/Makefile      |  1 +
 drivers/mfd/ch341-core.c  | 90 +++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/ch341.h | 18 ++++++++
 5 files changed, 126 insertions(+)
 create mode 100644 drivers/mfd/ch341-core.c
 create mode 100644 include/linux/mfd/ch341.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 43d3d07afccd..628eeaa9bf68 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21475,6 +21475,13 @@ M:	David Härdeman <david@hardeman.nu>
 S:	Maintained
 F:	drivers/media/rc/winbond-cir.c
 
+WINCHIPHEAD CH341 I2C/GPIO MFD DRIVER
+M:	Frank Zago <frank@zago.net>
+L:	linux-usb@vger.kernel.org
+S:	Maintained
+F:	drivers/mfd/ch341-core.c
+F:	include/linux/mfd/ch341.h
+
 WINSYSTEMS EBC-C384 WATCHDOG DRIVER
 M:	William Breathitt Gray <vilhelm.gray@gmail.com>
 L:	linux-watchdog@vger.kernel.org
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 3b59456f5545..893acc821a42 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1784,6 +1784,16 @@ config MFD_LOCHNAGAR
 	help
 	  Support for Cirrus Logic Lochnagar audio development board.
 
+config MFD_CH341
+	tristate "WinChipHead CH341 in I2C/SPI/GPIO mode"
+	depends on USB
+	help
+	  If you say yes to this option, support for the CH341 series
+	  of chips, running in I2C/SPI/GPIO mode will be included.
+
+	  This driver can also be built as a module.  If so, the
+	  module will be called ch341-core.
+
 config MFD_ARIZONA
 	select REGMAP
 	select REGMAP_IRQ
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 858cacf659d6..fd615ab3929f 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_MFD_ASIC3)		+= asic3.o tmio_core.o
 obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835-pm.o
 obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
 obj-$(CONFIG_MFD_BD9571MWV)	+= bd9571mwv.o
+obj-$(CONFIG_MFD_CH341)		+= ch341-core.o
 obj-$(CONFIG_MFD_CROS_EC_DEV)	+= cros_ec_dev.o
 obj-$(CONFIG_MFD_ENE_KB3930)	+= ene-kb3930.o
 obj-$(CONFIG_MFD_EXYNOS_LPASS)	+= exynos-lpass.o
diff --git a/drivers/mfd/ch341-core.c b/drivers/mfd/ch341-core.c
new file mode 100644
index 000000000000..f08a67dd6074
--- /dev/null
+++ b/drivers/mfd/ch341-core.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Core driver for the CH341A, CH341B and CH341T in I2C/SPI/GPIO
+ * mode. There are cell drivers available for I2C and GPIO. SPI is not
+ * yet supported.
+ *
+ * Copyright 2022, Frank Zago
+ * Copyright (c) 2017 Gunar Schorcht (gunar@schorcht.net)
+ * Copyright (c) 2016 Tse Lun Bien
+ * Copyright (c) 2014 Marco Gittler
+ * Copyright (c) 2006-2007 Till Harbaum (Till@Harbaum.org)
+ */
+
+#include <linux/kernel.h>
+#include <linux/mfd/ch341.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+static const struct mfd_cell ch341_devs[] = {
+	{
+		.name = "ch341-gpio",
+	},
+	{
+		.name = "ch341-i2c",
+	},
+};
+
+static int ch341_usb_probe(struct usb_interface *iface,
+			   const struct usb_device_id *usb_id)
+{
+	struct usb_endpoint_descriptor *bulk_out;
+	struct usb_endpoint_descriptor *bulk_in;
+	struct usb_endpoint_descriptor *intr_in;
+	struct ch341_ddata *ddata;
+	int ret;
+
+	ddata = devm_kzalloc(&iface->dev, sizeof(*ddata), GFP_KERNEL);
+	if (!ddata)
+		return -ENOMEM;
+
+	ddata->usb_dev = interface_to_usbdev(iface);
+	mutex_init(&ddata->usb_lock);
+
+	ret = usb_find_common_endpoints(iface->cur_altsetting, &bulk_in,
+					&bulk_out, &intr_in, NULL);
+	if (ret) {
+		dev_err(&iface->dev, "Could not find all endpoints\n");
+		return -ENODEV;
+	}
+
+	ddata->ep_in = bulk_in->bEndpointAddress;
+	ddata->ep_out = bulk_out->bEndpointAddress;
+	ddata->ep_intr = intr_in->bEndpointAddress;
+	ddata->ep_intr_interval = intr_in->bInterval;
+
+	usb_set_intfdata(iface, ddata);
+
+	ret = mfd_add_devices(&iface->dev, PLATFORM_DEVID_AUTO, ch341_devs,
+			      ARRAY_SIZE(ch341_devs), NULL, 0, NULL);
+	if (ret)
+		return dev_err_probe(&iface->dev, ret,
+				     "Failed to register child devices\n");
+
+	return 0;
+}
+
+static void ch341_usb_disconnect(struct usb_interface *usb_if)
+{
+	mfd_remove_devices(&usb_if->dev);
+}
+
+static const struct usb_device_id ch341_usb_table[] = {
+	{ USB_DEVICE(0x1a86, 0x5512) },
+	{ }
+};
+MODULE_DEVICE_TABLE(usb, ch341_usb_table);
+
+static struct usb_driver ch341_usb_driver = {
+	.name       = "ch341-mfd",
+	.id_table   = ch341_usb_table,
+	.probe      = ch341_usb_probe,
+	.disconnect = ch341_usb_disconnect,
+};
+module_usb_driver(ch341_usb_driver);
+
+MODULE_AUTHOR("Frank Zago <frank@zago.net>");
+MODULE_DESCRIPTION("CH341 USB to I2C/SPI/GPIO adapter");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/mfd/ch341.h b/include/linux/mfd/ch341.h
new file mode 100644
index 000000000000..44f5da0720bd
--- /dev/null
+++ b/include/linux/mfd/ch341.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Definitions for the CH341 driver */
+
+#include <linux/mutex.h>
+#include <linux/types.h>
+
+struct usb_device;
+struct usb_interface;
+
+struct ch341_ddata {
+	struct usb_device *usb_dev;
+	struct mutex usb_lock;
+
+	int ep_in;
+	int ep_out;
+	int ep_intr;
+	u8 ep_intr_interval;
+};
-- 
2.32.0

[PATCH v6 2/4] gpio: ch341: add GPIO MFD cell driver for the CH341

[frank zago]

The GPIO interface offers 16 GPIOs. 6 are read/write, and 10 are
read-only.

Signed-off-by: frank zago <frank@zago.net>
---
 MAINTAINERS               |   1 +
 drivers/gpio/Kconfig      |  10 +
 drivers/gpio/Makefile     |   1 +
 drivers/gpio/gpio-ch341.c | 385 ++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/ch341.h |   8 +
 5 files changed, 405 insertions(+)
 create mode 100644 drivers/gpio/gpio-ch341.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 628eeaa9bf68..8b93f6192704 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21479,6 +21479,7 @@ WINCHIPHEAD CH341 I2C/GPIO MFD DRIVER
 M:	Frank Zago <frank@zago.net>
 L:	linux-usb@vger.kernel.org
 S:	Maintained
+F:	drivers/gpio/gpio-ch341.c
 F:	drivers/mfd/ch341-core.c
 F:	include/linux/mfd/ch341.h
 
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index b01961999ced..473b6e7226ca 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1653,6 +1653,16 @@ endmenu
 menu "USB GPIO expanders"
 	depends on USB
 
+config GPIO_CH341
+	tristate "CH341 USB to GPIO support"
+	select MFD_CH341
+	help
+	  If you say yes to this option, GPIO support will be included for the
+	  WCH CH341, a USB to I2C/SPI/GPIO interface.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called gpio-ch341.
+
 config GPIO_VIPERBOARD
 	tristate "Viperboard GPIO a & b support"
 	depends on MFD_VIPERBOARD
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 14352f6dfe8e..beef802cbfb1 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -44,6 +44,7 @@ obj-$(CONFIG_GPIO_BD9571MWV)		+= gpio-bd9571mwv.o
 obj-$(CONFIG_GPIO_BRCMSTB)		+= gpio-brcmstb.o
 obj-$(CONFIG_GPIO_BT8XX)		+= gpio-bt8xx.o
 obj-$(CONFIG_GPIO_CADENCE)		+= gpio-cadence.o
+obj-$(CONFIG_GPIO_CH341)		+= gpio-ch341.o
 obj-$(CONFIG_GPIO_CLPS711X)		+= gpio-clps711x.o
 obj-$(CONFIG_GPIO_SNPS_CREG)		+= gpio-creg-snps.o
 obj-$(CONFIG_GPIO_CRYSTAL_COVE)		+= gpio-crystalcove.o
diff --git a/drivers/gpio/gpio-ch341.c b/drivers/gpio/gpio-ch341.c
new file mode 100644
index 000000000000..233dfe1f2ae8
--- /dev/null
+++ b/drivers/gpio/gpio-ch341.c
@@ -0,0 +1,385 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * GPIO cell driver for the CH341A and CH341B chips.
+ *
+ * Copyright 2022, Frank Zago
+ * Copyright (c) 2017 Gunar Schorcht (gunar@schorcht.net)
+ * Copyright (c) 2016 Tse Lun Bien
+ * Copyright (c) 2014 Marco Gittler
+ * Copyright (c) 2006-2007 Till Harbaum (Till@Harbaum.org)
+ */
+
+/*
+ * Notes.
+ *
+ * For the CH341, 0=IN, 1=OUT, but for the GPIO subsystem, 1=IN and
+ * 0=OUT. Translation happens in a couple places.
+ */
+
+#include <linux/gpio/driver.h>
+#include <linux/kernel.h>
+#include <linux/mfd/ch341.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include <linux/usb.h>
+
+#define CH341_GPIO_NUM_PINS         16    /* Number of GPIO pins */
+
+/* GPIO chip commands */
+#define CH341_PARA_CMD_STS          0xA0  /* Get pins status */
+#define CH341_CMD_UIO_STREAM        0xAB  /* pin IO stream command */
+
+#define CH341_CMD_UIO_STM_OUT       0x80  /* pin IO interface OUT command (D0~D5) */
+#define CH341_CMD_UIO_STM_DIR       0x40  /* pin IO interface DIR command (D0~D5) */
+#define CH341_CMD_UIO_STM_END       0x20  /* pin IO interface END command */
+
+#define CH341_USB_MAX_INTR_SIZE 8
+
+struct ch341_gpio {
+	struct gpio_chip gpio;
+	struct mutex gpio_lock;
+	u16 gpio_dir;		/* 1 bit per pin, 0=IN, 1=OUT. */
+	u16 gpio_last_read;	/* last GPIO values read */
+	u16 gpio_last_written;	/* last GPIO values written */
+	union {
+		u8 gpio_buf[SEG_SIZE];
+		__le16 gpio_buf_status;
+	};
+
+	struct urb *irq_urb;
+	struct usb_anchor irq_urb_out;
+	u8 irq_buf[CH341_USB_MAX_INTR_SIZE];
+	struct irq_chip irq_chip;
+
+	struct ch341_ddata *ddata;
+};
+
+/*
+ * Masks to describe the 16 GPIOs. Pins D0 to D5 (mapped to GPIOs 0 to
+ * 5) can do input/output, but the other pins are input-only.
+ */
+static const u16 pin_can_output = 0b111111;
+
+/* Only GPIO 10 (INT# line) has hardware interrupt */
+#define CH341_GPIO_INT_LINE 10
+
+/* Send a command and get a reply if requested */
+static int gpio_transfer(struct ch341_gpio *dev, int out_len, int in_len)
+{
+	struct ch341_ddata *ddata = dev->ddata;
+	int actual;
+	int ret;
+
+	mutex_lock(&ddata->usb_lock);
+
+	ret = usb_bulk_msg(ddata->usb_dev,
+			   usb_sndbulkpipe(ddata->usb_dev, ddata->ep_out),
+			   dev->gpio_buf, out_len,
+			   &actual, DEFAULT_TIMEOUT_MS);
+	if (ret < 0)
+		goto out_unlock;
+
+	if (in_len == 0)
+		goto out_unlock;
+
+	ret = usb_bulk_msg(ddata->usb_dev,
+			   usb_rcvbulkpipe(ddata->usb_dev, ddata->ep_in),
+			   dev->gpio_buf, SEG_SIZE, &actual, DEFAULT_TIMEOUT_MS);
+
+out_unlock:
+	mutex_unlock(&ddata->usb_lock);
+
+	if (ret < 0)
+		return ret;
+
+	return actual;
+}
+
+/* Read the GPIO line status. */
+static int read_inputs(struct ch341_gpio *dev)
+{
+	int ret;
+
+	mutex_lock(&dev->gpio_lock);
+
+	dev->gpio_buf[0] = CH341_PARA_CMD_STS;
+
+	ret = gpio_transfer(dev, 1, 1);
+
+	/*
+	 * The status command returns 6 bytes of data. Byte 0 has
+	 * status for lines 0 to 7, and byte 1 is lines 8 to 15. The
+	 * 3rd has the status for the SCL/SDA/SCK pins. The 4th byte
+	 * might have some remaining pin status. Byte 5 and 6 content
+	 * is unknown.
+	 */
+	if (ret == 6)
+		dev->gpio_last_read = le16_to_cpu(dev->gpio_buf_status);
+	else
+		ret = -EIO;
+
+	mutex_unlock(&dev->gpio_lock);
+
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int ch341_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct ch341_gpio *dev = gpiochip_get_data(chip);
+	int ret;
+
+	ret = read_inputs(dev);
+	if (ret)
+		return ret;
+
+	return !!(dev->gpio_last_read & BIT(offset));
+}
+
+static int ch341_gpio_get_multiple(struct gpio_chip *chip,
+				   unsigned long *mask, unsigned long *bits)
+{
+	struct ch341_gpio *dev = gpiochip_get_data(chip);
+	int ret;
+
+	ret = read_inputs(dev);
+	if (ret)
+		return ret;
+
+	*bits = dev->gpio_last_read & *mask;
+
+	return 0;
+}
+
+static void write_outputs(struct ch341_gpio *dev)
+{
+	mutex_lock(&dev->gpio_lock);
+
+	/* Only the first 6 lines can output. */
+	dev->gpio_buf[0] = CH341_CMD_UIO_STREAM;
+	dev->gpio_buf[1] = CH341_CMD_UIO_STM_DIR | (dev->gpio_dir & pin_can_output);
+	dev->gpio_buf[2] = CH341_CMD_UIO_STM_OUT |
+		(dev->gpio_last_written & dev->gpio_dir & pin_can_output);
+	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_gpio *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_gpio *dev = gpiochip_get_data(chip);
+
+	dev->gpio_last_written = (dev->gpio_last_written & ~*mask) | (*bits & *mask);
+
+	write_outputs(dev);
+}
+
+static int ch341_gpio_get_direction(struct gpio_chip *chip,
+				    unsigned int offset)
+{
+	struct ch341_gpio *dev = gpiochip_get_data(chip);
+
+	return !(dev->gpio_dir & BIT(offset));
+}
+
+static int ch341_gpio_direction_input(struct gpio_chip *chip,
+				      unsigned int offset)
+{
+	struct ch341_gpio *dev = gpiochip_get_data(chip);
+
+	dev->gpio_dir &= ~BIT(offset);
+
+	write_outputs(dev);
+
+	return 0;
+}
+
+static int ch341_gpio_direction_output(struct gpio_chip *chip,
+				       unsigned int offset, int value)
+{
+	struct ch341_gpio *dev = gpiochip_get_data(chip);
+	u16 mask = BIT(offset);
+
+	if (!(pin_can_output & mask))
+		return -EINVAL;
+
+	dev->gpio_dir |= mask;
+
+	ch341_gpio_set(chip, offset, value);
+
+	return 0;
+}
+
+static void ch341_complete_intr_urb(struct urb *urb)
+{
+	struct ch341_gpio *dev = urb->context;
+	int ret;
+
+	if (urb->status) {
+		usb_unanchor_urb(dev->irq_urb);
+	} else {
+		/*
+		 * Data is 8 bytes. Byte 0 might be the length of
+		 * significant data, which is 3 more bytes. Bytes 1
+		 * and 2, and possibly 3, are the pin status. The byte
+		 * order is different than for the GET_STATUS
+		 * command. Byte 1 is GPIOs 8 to 15, and byte 2 is
+		 * GPIOs 0 to 7.
+		 */
+
+		handle_nested_irq(irq_find_mapping(dev->gpio.irq.domain,
+						   CH341_GPIO_INT_LINE));
+
+		ret = usb_submit_urb(dev->irq_urb, GFP_ATOMIC);
+		if (ret)
+			usb_unanchor_urb(dev->irq_urb);
+	}
+}
+
+static int ch341_gpio_irq_set_type(struct irq_data *data, unsigned int flow_type)
+{
+	const unsigned long offset = irqd_to_hwirq(data);
+
+	if (offset != CH341_GPIO_INT_LINE || flow_type != IRQ_TYPE_EDGE_RISING)
+		return -EINVAL;
+
+	return 0;
+}
+
+static void ch341_gpio_irq_enable(struct irq_data *data)
+{
+	struct ch341_gpio *dev = irq_data_get_irq_chip_data(data);
+	int ret;
+
+	/*
+	 * The URB might have just been unlinked in
+	 * ch341_gpio_irq_disable, but the completion handler hasn't
+	 * been called yet.
+	 */
+	if (!usb_wait_anchor_empty_timeout(&dev->irq_urb_out, 5000))
+		usb_kill_anchored_urbs(&dev->irq_urb_out);
+
+	usb_anchor_urb(dev->irq_urb, &dev->irq_urb_out);
+	ret = usb_submit_urb(dev->irq_urb, GFP_KERNEL);
+	if (ret)
+		usb_unanchor_urb(dev->irq_urb);
+}
+
+static void ch341_gpio_irq_disable(struct irq_data *data)
+{
+	struct ch341_gpio *dev = irq_data_get_irq_chip_data(data);
+
+	usb_unlink_urb(dev->irq_urb);
+}
+
+static int ch341_gpio_remove(struct platform_device *pdev)
+{
+	struct ch341_gpio *dev = platform_get_drvdata(pdev);
+
+	usb_kill_anchored_urbs(&dev->irq_urb_out);
+	gpiochip_remove(&dev->gpio);
+	usb_free_urb(dev->irq_urb);
+
+	return 0;
+}
+
+static const struct irq_chip ch341_irqchip = {
+	.name = "CH341",
+	.irq_set_type = ch341_gpio_irq_set_type,
+	.irq_enable = ch341_gpio_irq_enable,
+	.irq_disable = ch341_gpio_irq_disable,
+	.flags = IRQCHIP_IMMUTABLE,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
+};
+
+static int ch341_gpio_probe(struct platform_device *pdev)
+{
+	struct ch341_ddata *ddata = dev_get_drvdata(pdev->dev.parent);
+	struct gpio_irq_chip *girq;
+	struct ch341_gpio *dev;
+	struct gpio_chip *gpio;
+	int ret;
+
+	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
+	if (dev == NULL)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, dev);
+	dev->ddata = ddata;
+	mutex_init(&dev->gpio_lock);
+
+	gpio = &dev->gpio;
+	gpio->label = dev_name(&pdev->dev);
+	gpio->parent = &pdev->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->base = -1;
+	gpio->ngpio = CH341_GPIO_NUM_PINS;
+	gpio->can_sleep = true;
+
+	girq = &gpio->irq;
+	gpio_irq_chip_set_chip(girq, &ch341_irqchip);
+	girq->handler = handle_simple_irq;
+	girq->default_type = IRQ_TYPE_NONE;
+
+	/* Create an URB for handling interrupt */
+	dev->irq_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!dev->irq_urb)
+		return dev_err_probe(&pdev->dev, -ENOMEM, "Cannot allocate the int URB\n");
+
+	usb_fill_int_urb(dev->irq_urb, ddata->usb_dev,
+			 usb_rcvintpipe(ddata->usb_dev, ddata->ep_intr),
+			 dev->irq_buf, CH341_USB_MAX_INTR_SIZE,
+			 ch341_complete_intr_urb, dev, ddata->ep_intr_interval);
+
+	init_usb_anchor(&dev->irq_urb_out);
+
+	ret = gpiochip_add_data(gpio, dev);
+	if (ret) {
+		ret = dev_err_probe(&pdev->dev, ret, "Could not add GPIO\n");
+		goto release_urb;
+	}
+
+	return 0;
+
+release_urb:
+	usb_free_urb(dev->irq_urb);
+
+	return ret;
+}
+
+static struct platform_driver ch341_gpio_driver = {
+	.driver.name	= "ch341-gpio",
+	.probe		= ch341_gpio_probe,
+	.remove		= ch341_gpio_remove,
+};
+module_platform_driver(ch341_gpio_driver);
+
+MODULE_AUTHOR("Frank Zago <frank@zago.net>");
+MODULE_DESCRIPTION("CH341 USB to GPIO");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ch341-gpio");
diff --git a/include/linux/mfd/ch341.h b/include/linux/mfd/ch341.h
index 44f5da0720bd..804d671fbe45 100644
--- a/include/linux/mfd/ch341.h
+++ b/include/linux/mfd/ch341.h
@@ -4,6 +4,14 @@
 #include <linux/mutex.h>
 #include <linux/types.h>
 
+#define DEFAULT_TIMEOUT_MS 1000	/* 1s USB requests timeout */
+
+/*
+ * All commands fit inside a 32-byte segment. There may be several of
+ * these segments in a USB command.
+ */
+#define SEG_SIZE 32
+
 struct usb_device;
 struct usb_interface;
 
-- 
2.32.0

[PATCH v6 3/4] i2c: ch341: add I2C MFD cell driver for the CH341

[frank zago]

The I2C interface can run at 4 different speeds. This driver currently
only offer 100kHz. Tested with a variety of I2C sensors, and the IIO
subsystem.

Signed-off-by: frank zago <frank@zago.net>
---
 MAINTAINERS                    |   1 +
 drivers/i2c/busses/Kconfig     |  10 +
 drivers/i2c/busses/Makefile    |   1 +
 drivers/i2c/busses/i2c-ch341.c | 377 +++++++++++++++++++++++++++++++++
 4 files changed, 389 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-ch341.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 8b93f6192704..837065fd3150 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21480,6 +21480,7 @@ M:	Frank Zago <frank@zago.net>
 L:	linux-usb@vger.kernel.org
 S:	Maintained
 F:	drivers/gpio/gpio-ch341.c
+F:	drivers/i2c/busses/i2c-ch341.c
 F:	drivers/mfd/ch341-core.c
 F:	include/linux/mfd/ch341.h
 
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index a1bae59208e3..db9797345ad5 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1199,6 +1199,16 @@ config I2C_RCAR
 
 comment "External I2C/SMBus adapter drivers"
 
+config I2C_CH341
+	tristate "CH341 USB to I2C support"
+	select MFD_CH341
+	help
+	  If you say yes to this option, I2C support will be included for the
+	  WCH CH341, a USB to I2C/SPI/GPIO interface.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-ch341.
+
 config I2C_DIOLAN_U2C
 	tristate "Diolan U2C-12 USB adapter"
 	depends on USB
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 479f60e4ee3d..e83ca4a472f2 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -127,6 +127,7 @@ obj-$(CONFIG_I2C_XLP9XX)	+= i2c-xlp9xx.o
 obj-$(CONFIG_I2C_RCAR)		+= i2c-rcar.o
 
 # External I2C/SMBus adapter drivers
+obj-$(CONFIG_I2C_CH341)		+= i2c-ch341.o
 obj-$(CONFIG_I2C_DIOLAN_U2C)	+= i2c-diolan-u2c.o
 obj-$(CONFIG_I2C_DLN2)		+= i2c-dln2.o
 obj-$(CONFIG_I2C_CP2615) += i2c-cp2615.o
diff --git a/drivers/i2c/busses/i2c-ch341.c b/drivers/i2c/busses/i2c-ch341.c
new file mode 100644
index 000000000000..60c587cca4eb
--- /dev/null
+++ b/drivers/i2c/busses/i2c-ch341.c
@@ -0,0 +1,377 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * I2C cell driver for the CH341A, CH341B and CH341T.
+ *
+ * Copyright 2022, Frank Zago
+ * Copyright (c) 2016 Tse Lun Bien
+ * Copyright (c) 2014 Marco Gittler
+ * Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org)
+ */
+
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/mfd/ch341.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include <linux/usb.h>
+
+/* I2C bus speed. Speed selection is not implemented. */
+#define CH341_I2C_20KHZ  0
+#define CH341_I2C_100KHZ 1
+#define CH341_I2C_400KHZ 2
+#define CH341_I2C_750KHZ 3
+
+/* I2C chip commands */
+#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
+
+/*
+ * The maximum request size is 4096 bytes, both for reading and
+ * writing, split in up to 128 32-byte segments, which includes the
+ * CH341 commands and the I2C data.
+ */
+#define SEG_COUNT 128
+
+/*
+ * Limit the transfer size that can be written. 4KiB is the maximum
+ * size of the whole buffer, but it must include all the command
+ * delimiters. 3KiB sounds reasonable.
+ */
+#define MAX_RW_LENGTH 3072
+
+struct ch341_i2c {
+	struct i2c_adapter adapter;
+
+	/* I2C request and response state */
+	int idx_out;		/* current offset in buf */
+	int out_seg;		/* current segment */
+	u8 i2c_buf[SEG_COUNT * SEG_SIZE];
+};
+
+/*
+ * Special case the no data transfer (SMBUS quick message), since some
+ * parameters are a bit different than the normal case.
+ */
+static int no_data_xfer(struct i2c_adapter *adapter, const struct i2c_msg *msg)
+{
+	struct ch341_i2c *dev = i2c_get_adapdata(adapter);
+	struct ch341_ddata *ddata = adapter->algo_data;
+	u8 *out = dev->i2c_buf;
+	int actual;
+	int ret;
+
+	out[0] = CH341_CMD_I2C_STREAM;
+	out[1] = CH341_CMD_I2C_STM_STA;
+	out[2] = CH341_CMD_I2C_STM_OUT;
+	out[3] = msg->addr << 1 | (msg->flags & I2C_M_RD);
+	out[4] = CH341_CMD_I2C_STM_IN;
+	out[5] = CH341_CMD_I2C_STM_STO;
+	out[6] = CH341_CMD_I2C_STM_END;
+
+	mutex_lock(&ddata->usb_lock);
+
+	/* Issue the request */
+	ret = usb_bulk_msg(ddata->usb_dev,
+			   usb_sndbulkpipe(ddata->usb_dev, ddata->ep_out),
+			   dev->i2c_buf, 7, &actual, DEFAULT_TIMEOUT_MS);
+	if (ret < 0) {
+		mutex_unlock(&ddata->usb_lock);
+		return ret;
+	}
+
+	ret = usb_bulk_msg(ddata->usb_dev,
+			   usb_rcvbulkpipe(ddata->usb_dev, ddata->ep_in),
+			   dev->i2c_buf, 2, &actual,
+			   DEFAULT_TIMEOUT_MS);
+	if (ret < 0) {
+		mutex_unlock(&ddata->usb_lock);
+		return ret;
+	}
+
+	mutex_unlock(&ddata->usb_lock);
+
+	if (actual != 2 || dev->i2c_buf[0] & 0x80)
+		return -ETIMEDOUT;
+
+	return 1;
+}
+
+/*
+ * Append a write command to the current request. A set of 32-byte
+ * packets is filled. Each packet starts with STREAM and finishes with
+ * END, and contains an OUT field, leaving up to 29 bytes of data. The
+ * first packet must also include a START and the device address.
+ */
+static int append_write(struct ch341_i2c *dev, const struct i2c_msg *msg)
+{
+	bool start_done = false;
+	u8 *out = dev->i2c_buf;
+	int len;
+	u8 *p;
+
+	len = msg->len;
+	p = msg->buf;
+
+	while (len) {
+		int to_write;
+		int avail;
+
+		if (dev->idx_out % SEG_SIZE) {
+			/* Finish current packet, and advance to the next one */
+			out[dev->idx_out++] = CH341_CMD_I2C_STM_END;
+			dev->out_seg++;
+			dev->idx_out = dev->out_seg * SEG_SIZE;
+
+			if (dev->out_seg == SEG_COUNT)
+				return -E2BIG;
+		}
+
+		out[dev->idx_out++] = CH341_CMD_I2C_STREAM;
+
+		/* account for stream start and end */
+		avail = SEG_SIZE - 3;
+
+		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;
+		p += 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.  Each read command, of up to 32
+ * bytes, must be written to a new packet. It is not possible to
+ * concat them.
+ */
+static int append_read(struct ch341_i2c *dev, const struct i2c_msg *msg)
+{
+	bool start_done = false;
+	u8 *out = dev->i2c_buf;
+	int len;
+
+	len = msg->len;
+
+	while (len) {
+		int to_read;
+
+		if (dev->idx_out % SEG_SIZE) {
+			if (!start_done &&
+			    (dev->idx_out % SEG_SIZE) <  (SEG_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_seg++;
+				dev->idx_out = dev->out_seg * SEG_SIZE;
+
+				if (dev->out_seg == SEG_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_i2c *dev = i2c_get_adapdata(adapter);
+	struct ch341_ddata *ddata = adapter->algo_data;
+	u8 *out = dev->i2c_buf;
+	int actual;
+	int ret;
+	int i;
+
+	/* Special case */
+	if (num == 1 && msgs[0].len == 0)
+		return no_data_xfer(adapter, &msgs[0]);
+
+	/* Prepare the request */
+	dev->idx_out = 0;
+	dev->out_seg = 0;
+
+	for (i = 0; i != num; i++) {
+		if (msgs[i].flags & I2C_M_RD)
+			ret = append_read(dev, &msgs[i]);
+		else
+			ret = append_write(dev, &msgs[i]);
+
+		if (ret)
+			return ret;
+	}
+
+	/* Finish the last packet */
+	if (SEG_SIZE - (dev->idx_out % SEG_SIZE) < 2) {
+		out[dev->idx_out++] = CH341_CMD_I2C_STM_END;
+
+		dev->out_seg++;
+		if (dev->out_seg == SEG_COUNT)
+			return -E2BIG;
+
+		dev->idx_out = dev->out_seg * SEG_SIZE;
+
+		out[dev->idx_out++] = CH341_CMD_I2C_STREAM;
+	}
+
+	out[dev->idx_out++] = CH341_CMD_I2C_STM_STO;
+	out[dev->idx_out++] = CH341_CMD_I2C_STM_END;
+
+	mutex_lock(&ddata->usb_lock);
+
+	/* Issue the request */
+	ret = usb_bulk_msg(ddata->usb_dev,
+			   usb_sndbulkpipe(ddata->usb_dev, ddata->ep_out),
+			   dev->i2c_buf, dev->idx_out, &actual, DEFAULT_TIMEOUT_MS);
+	if (ret < 0) {
+		mutex_unlock(&ddata->usb_lock);
+		return ret;
+	}
+
+	for (i = 0; i != num; i++) {
+		if (!(msgs[i].flags & I2C_M_RD))
+			continue;
+
+		ret = usb_bulk_msg(ddata->usb_dev,
+				  usb_rcvbulkpipe(ddata->usb_dev, ddata->ep_in),
+				  dev->i2c_buf, msgs[i].len, &actual,
+				  DEFAULT_TIMEOUT_MS);
+
+		if (ret) {
+			mutex_unlock(&ddata->usb_lock);
+			return ret;
+		}
+
+		if (actual != msgs[i].len) {
+			mutex_unlock(&ddata->usb_lock);
+			return -EIO;
+		}
+
+		memcpy(msgs[i].buf, dev->i2c_buf, actual);
+	}
+
+	mutex_unlock(&ddata->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,
+};
+
+static const struct i2c_adapter_quirks ch341_i2c_quirks = {
+	.max_read_len = MAX_RW_LENGTH,
+	.max_write_len = MAX_RW_LENGTH,
+};
+
+static int ch341_i2c_probe(struct platform_device *pdev)
+{
+	struct ch341_ddata *ddata = dev_get_drvdata(pdev->dev.parent);
+	struct ch341_i2c *ch341_i2c;
+	int actual;
+	int ret;
+
+	ch341_i2c = devm_kzalloc(&pdev->dev, sizeof(*ch341_i2c), GFP_KERNEL);
+	if (ch341_i2c == NULL)
+		return -ENOMEM;
+
+	ch341_i2c->adapter.owner = THIS_MODULE;
+	ch341_i2c->adapter.class = I2C_CLASS_HWMON;
+	ch341_i2c->adapter.algo = &ch341_i2c_algorithm;
+	ch341_i2c->adapter.algo_data = ddata;
+	ch341_i2c->adapter.quirks = &ch341_i2c_quirks;
+	ch341_i2c->adapter.dev.parent = &pdev->dev;
+	snprintf(ch341_i2c->adapter.name, sizeof(ch341_i2c->adapter.name),
+		 "CH341 I2C USB bus %03d device %03d",
+		 ddata->usb_dev->bus->busnum, ddata->usb_dev->devnum);
+
+	i2c_set_adapdata(&ch341_i2c->adapter, ch341_i2c);
+	platform_set_drvdata(pdev, ch341_i2c);
+
+	/* Set ch341 i2c speed */
+	ch341_i2c->i2c_buf[0] = CH341_CMD_I2C_STREAM;
+	ch341_i2c->i2c_buf[1] = CH341_CMD_I2C_STM_SET | CH341_I2C_100KHZ;
+	ch341_i2c->i2c_buf[2] = CH341_CMD_I2C_STM_END;
+	mutex_lock(&ddata->usb_lock);
+	ret = usb_bulk_msg(ddata->usb_dev,
+			   usb_sndbulkpipe(ddata->usb_dev, ddata->ep_out),
+			   ch341_i2c->i2c_buf, 3, &actual, DEFAULT_TIMEOUT_MS);
+	mutex_unlock(&ddata->usb_lock);
+
+	if (ret < 0)
+		return dev_err_probe(&pdev->dev, ret, "Cannot set I2C speed\n");
+
+	return devm_i2c_add_adapter(&pdev->dev, &ch341_i2c->adapter);
+}
+
+static struct platform_driver ch341_i2c_driver = {
+	.driver.name	= "ch341-i2c",
+	.probe		= ch341_i2c_probe,
+};
+module_platform_driver(ch341_i2c_driver);
+
+MODULE_AUTHOR("Frank Zago <frank@zago.net>");
+MODULE_DESCRIPTION("CH341 USB to I2C");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ch341-i2c");
-- 
2.32.0

[PATCH v6 4/4] docs: misc: add documentation for ch341 driver

[frank zago]

Document the multifunction CH341 chip driver, in GPIO and I2C mode.

Signed-off-by: frank zago <frank@zago.net>
---
 Documentation/misc-devices/ch341.rst | 109 +++++++++++++++++++++++++++
 Documentation/misc-devices/index.rst |   1 +
 2 files changed, 110 insertions(+)
 create mode 100644 Documentation/misc-devices/ch341.rst

diff --git a/Documentation/misc-devices/ch341.rst b/Documentation/misc-devices/ch341.rst
new file mode 100644
index 000000000000..65ba293bdc2d
--- /dev/null
+++ b/Documentation/misc-devices/ch341.rst
@@ -0,0 +1,109 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+===========================================================
+WinChipHead (沁恒) CH341 linux driver for I2C and GPIO mode
+===========================================================
+
+The CH341 is declined in several flavors, and may support one or more
+of UART, SPI, I2C and GPIO, but not always simultaneously:
+
+  - CH341 A/B/F: UART, Printer, SPI, I2C and GPIO
+  - CH341 C/T: UART and I2C
+  - CH341 H: SPI
+
+They work in 3 different modes, with only one being presented
+depending on the USB PID:
+
+  - 0x5523: UART mode, covered by the USB `ch341` serial driver
+  - 0x5512: SPI/I2C/GPIO mode, covered by the ch341 MFD drivers
+  - 0x5584: Parallel printer mode, covered by the USB `usblp` driver
+
+Mode selection is done at the hardware level by tying some
+pins. Breakout boards with one of the CH341 chip usually have one or
+more jumpers to select which mode they work on. At least one model
+(CJMCU-341) appears to need bridging some solder pads to select a
+different default. Breakout boards also don't usually offer an option
+to configure the chip into printer mode; for that case, connect the
+SCL and SDA lines directly together.
+
+The various CH341 appear to be indistinguishable from the
+software. For instance the ch341 MFD driver will present a GPIO
+interface for the CH341T although physical pins are not present, and
+the device will accept GPIO commands.
+
+The ch341 MFD driver has been tested with a CH341A, CH341B and
+CH341T.
+
+Some breakout boards work in 3.3V and 5V depending on some jumpers.
+
+The black chip programmer with a ZIF socket will power the CH341 at
+3.3V if a jumper is set, but will only output 5V to the chips to be
+programmed, which is not always desirable. A hardware hack to use 3.3V
+everywhere, involving some soldering, is available at
+https://eevblog.com/forum/repair/ch341a-serial-memory-programmer-power-supply-fix/
+
+Some sample code for the CH341 is available at the manufacturer
+website, at http://wch-ic.com/products/CH341.html
+
+The repository at https://github.com/boseji/CH341-Store contains a lot
+of information on these chips, including datasheets.
+
+This driver is based on the pre-existing work at
+https://github.com/gschorcht/i2c-ch341-usb
+
+
+I2C Caveats
+-----------
+
+The ch341 doesn't work with a Wii nunchuk, possibly because the
+pull-up value is too low (1500 ohms).
+
+i2c AT24 eeproms can be read but not programmed properly because the
+at24 linux driver tries to write a byte at a time, and doesn't wait at
+all (or enough) between writes. Data corruption on writes does occur.
+
+
+The GPIOs
+---------
+
+16 GPIOs are available on the CH341 A/B/F. The first 6 are input/output,
+and the last 10 are input only.
+
+Pinout and their names as they appear on some breakout boards::
+
+  CH341A/B/F     GPIO  Names                    Mode
+    pin          line
+
+   15             0     D0, CS0                  input/output
+   16             1     D1, CS1                  input/output
+   17             2     D2, CS2                  input/output
+   18             3     D3, SCK, DCK             input/output
+   19             4     D4, DOUT2, CS3           input/output
+   20             5     D5, MOSI, DOUT, SDO      input/output
+   21             6     D6, DIN2                 input
+   22             7     D7, MISO, DIN            input
+    5             8     ERR                      input
+    6             9     PEMP                     input
+    7            10     INT                      input
+    8            11     SLCT (SELECT)            input
+   26            12     RST# (?)                 input
+   27            13     WT (WAIT)                input
+    4            14     DS (Data Select?)        input
+    3            15     AS (Address Select?)     input
+
+
+GPIO interrupt
+~~~~~~~~~~~~~~
+
+The INT pin, corresponding to GPIO 10 is an input pin that can trigger
+an interrupt on a rising edge. Only that pin is able to generate an
+interrupt, and only on a rising edge. Trying to monitor events on
+another GPIO, or that GPIO on something other than a rising edge, will
+be rejected.
+
+
+SPI
+---
+
+This driver doesn't offer an SPI interface (yet) due to the
+impossibility of declaring an SPI device like I2C does.
diff --git a/Documentation/misc-devices/index.rst b/Documentation/misc-devices/index.rst
index 756be15a49a4..e85531a4f354 100644
--- a/Documentation/misc-devices/index.rst
+++ b/Documentation/misc-devices/index.rst
@@ -19,6 +19,7 @@ fit into other categories.
    bh1770glc
    eeprom
    c2port
+   ch341
    dw-xdata-pcie
    ibmvmc
    ics932s401
-- 
2.32.0

Re: [PATCH v6 3/4] i2c: ch341: add I2C MFD cell driver for the CH341

[Randy Dunlap]

Hi--

On 6/15/22 18:37, frank zago wrote:
> The I2C interface can run at 4 different speeds. This driver currently
> only offer 100kHz. Tested with a variety of I2C sensors, and the IIO
> subsystem.
> 
> Signed-off-by: frank zago <frank@zago.net>
> ---
>  MAINTAINERS                    |   1 +
>  drivers/i2c/busses/Kconfig     |  10 +
>  drivers/i2c/busses/Makefile    |   1 +
>  drivers/i2c/busses/i2c-ch341.c | 377 +++++++++++++++++++++++++++++++++
>  4 files changed, 389 insertions(+)
>  create mode 100644 drivers/i2c/busses/i2c-ch341.c
> 

> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index a1bae59208e3..db9797345ad5 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -1199,6 +1199,16 @@ config I2C_RCAR
>  
>  comment "External I2C/SMBus adapter drivers"
>  
> +config I2C_CH341
> +	tristate "CH341 USB to I2C support"
> +	select MFD_CH341
> +	help
> +	  If you say yes to this option, I2C support will be included for the
> +	  WCH CH341, a USB to I2C/SPI/GPIO interface.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called i2c-ch341.

I haven't tested it, but just from reading, it looks like
this one needs a "depends on USB" since it selects MFD_CH341, which
depends on USB, and since 'select' ignores dependency chains.

The GPIO driver (patch 2/4) already depends on USB.

-- 
~Randy

Re: [PATCH v6 3/4] i2c: ch341: add I2C MFD cell driver for the CH341

[kernel test robot]

Hi frank,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on lee-mfd/for-mfd-next]
[also build test ERROR on brgl/gpio/for-next wsa/i2c/for-next linus/master v5.19-rc2 next-20220615]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/intel-lab-lkp/linux/commits/frank-zago/add-driver-for-the-WCH-CH341-in-I2C-GPIO-mode/20220616-094113
base:   https://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd.git for-mfd-next
config: nios2-randconfig-r026-20220616 (https://download.01.org/0day-ci/archive/20220616/202206161751.5icAiwNf-lkp@intel.com/config)
compiler: nios2-linux-gcc (GCC) 11.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/46c68aee86d34ee630272146a73ad7c3147bb094
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review frank-zago/add-driver-for-the-WCH-CH341-in-I2C-GPIO-mode/20220616-094113
        git checkout 46c68aee86d34ee630272146a73ad7c3147bb094
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=nios2 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   nios2-linux-ld: drivers/mfd/ch341-core.o: in function `ch341_usb_probe':
>> drivers/mfd/ch341-core.c:46: undefined reference to `usb_find_common_endpoints'
   drivers/mfd/ch341-core.c:46:(.text+0x8c): relocation truncated to fit: R_NIOS2_CALL26 against `usb_find_common_endpoints'
   nios2-linux-ld: drivers/mfd/ch341-core.o: in function `ch341_usb_driver_init':
>> drivers/mfd/ch341-core.c:86: undefined reference to `usb_register_driver'
   drivers/mfd/ch341-core.c:86:(.init.text+0x1c): relocation truncated to fit: R_NIOS2_CALL26 against `usb_register_driver'
   nios2-linux-ld: drivers/i2c/busses/i2c-ch341.o: in function `no_data_xfer':
>> drivers/i2c/busses/i2c-ch341.c:81: undefined reference to `usb_bulk_msg'
   drivers/i2c/busses/i2c-ch341.c:81:(.text+0xe0): relocation truncated to fit: R_NIOS2_CALL26 against `usb_bulk_msg'
>> nios2-linux-ld: drivers/i2c/busses/i2c-ch341.c:89: undefined reference to `usb_bulk_msg'
   drivers/i2c/busses/i2c-ch341.c:89:(.text+0x134): relocation truncated to fit: R_NIOS2_CALL26 against `usb_bulk_msg'
   nios2-linux-ld: drivers/i2c/busses/i2c-ch341.o: in function `ch341_i2c_xfer':
   drivers/i2c/busses/i2c-ch341.c:278: undefined reference to `usb_bulk_msg'
   drivers/i2c/busses/i2c-ch341.c:278:(.text+0x4e0): relocation truncated to fit: R_NIOS2_CALL26 against `usb_bulk_msg'
   nios2-linux-ld: drivers/i2c/busses/i2c-ch341.c:290: undefined reference to `usb_bulk_msg'
   drivers/i2c/busses/i2c-ch341.c:290:(.text+0x558): relocation truncated to fit: R_NIOS2_CALL26 against `usb_bulk_msg'
   nios2-linux-ld: drivers/i2c/busses/i2c-ch341.o: in function `ch341_i2c_probe':
   drivers/i2c/busses/i2c-ch341.c:357: undefined reference to `usb_bulk_msg'
   drivers/i2c/busses/i2c-ch341.c:357:(.text+0x778): relocation truncated to fit: R_NIOS2_CALL26 against `usb_bulk_msg'
   pahole: .tmp_vmlinux.btf: No such file or directory
   .btf.vmlinux.bin.o: file not recognized: file format not recognized

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for MFD_CH341
   Depends on HAS_IOMEM && USB
   Selected by
   - I2C_CH341 && I2C && HAS_IOMEM


vim +46 drivers/mfd/ch341-core.c

f33ee28d4d85a8 frank zago 2022-06-15  29  
f33ee28d4d85a8 frank zago 2022-06-15  30  static int ch341_usb_probe(struct usb_interface *iface,
f33ee28d4d85a8 frank zago 2022-06-15  31  			   const struct usb_device_id *usb_id)
f33ee28d4d85a8 frank zago 2022-06-15  32  {
f33ee28d4d85a8 frank zago 2022-06-15  33  	struct usb_endpoint_descriptor *bulk_out;
f33ee28d4d85a8 frank zago 2022-06-15  34  	struct usb_endpoint_descriptor *bulk_in;
f33ee28d4d85a8 frank zago 2022-06-15  35  	struct usb_endpoint_descriptor *intr_in;
f33ee28d4d85a8 frank zago 2022-06-15  36  	struct ch341_ddata *ddata;
f33ee28d4d85a8 frank zago 2022-06-15  37  	int ret;
f33ee28d4d85a8 frank zago 2022-06-15  38  
f33ee28d4d85a8 frank zago 2022-06-15  39  	ddata = devm_kzalloc(&iface->dev, sizeof(*ddata), GFP_KERNEL);
f33ee28d4d85a8 frank zago 2022-06-15  40  	if (!ddata)
f33ee28d4d85a8 frank zago 2022-06-15  41  		return -ENOMEM;
f33ee28d4d85a8 frank zago 2022-06-15  42  
f33ee28d4d85a8 frank zago 2022-06-15  43  	ddata->usb_dev = interface_to_usbdev(iface);
f33ee28d4d85a8 frank zago 2022-06-15  44  	mutex_init(&ddata->usb_lock);
f33ee28d4d85a8 frank zago 2022-06-15  45  
f33ee28d4d85a8 frank zago 2022-06-15 @46  	ret = usb_find_common_endpoints(iface->cur_altsetting, &bulk_in,
f33ee28d4d85a8 frank zago 2022-06-15  47  					&bulk_out, &intr_in, NULL);
f33ee28d4d85a8 frank zago 2022-06-15  48  	if (ret) {
f33ee28d4d85a8 frank zago 2022-06-15  49  		dev_err(&iface->dev, "Could not find all endpoints\n");
f33ee28d4d85a8 frank zago 2022-06-15  50  		return -ENODEV;
f33ee28d4d85a8 frank zago 2022-06-15  51  	}
f33ee28d4d85a8 frank zago 2022-06-15  52  
f33ee28d4d85a8 frank zago 2022-06-15  53  	ddata->ep_in = bulk_in->bEndpointAddress;
f33ee28d4d85a8 frank zago 2022-06-15  54  	ddata->ep_out = bulk_out->bEndpointAddress;
f33ee28d4d85a8 frank zago 2022-06-15  55  	ddata->ep_intr = intr_in->bEndpointAddress;
f33ee28d4d85a8 frank zago 2022-06-15  56  	ddata->ep_intr_interval = intr_in->bInterval;
f33ee28d4d85a8 frank zago 2022-06-15  57  
f33ee28d4d85a8 frank zago 2022-06-15  58  	usb_set_intfdata(iface, ddata);
f33ee28d4d85a8 frank zago 2022-06-15  59  
f33ee28d4d85a8 frank zago 2022-06-15  60  	ret = mfd_add_devices(&iface->dev, PLATFORM_DEVID_AUTO, ch341_devs,
f33ee28d4d85a8 frank zago 2022-06-15  61  			      ARRAY_SIZE(ch341_devs), NULL, 0, NULL);
f33ee28d4d85a8 frank zago 2022-06-15  62  	if (ret)
f33ee28d4d85a8 frank zago 2022-06-15  63  		return dev_err_probe(&iface->dev, ret,
f33ee28d4d85a8 frank zago 2022-06-15  64  				     "Failed to register child devices\n");
f33ee28d4d85a8 frank zago 2022-06-15  65  
f33ee28d4d85a8 frank zago 2022-06-15  66  	return 0;
f33ee28d4d85a8 frank zago 2022-06-15  67  }
f33ee28d4d85a8 frank zago 2022-06-15  68  
f33ee28d4d85a8 frank zago 2022-06-15  69  static void ch341_usb_disconnect(struct usb_interface *usb_if)
f33ee28d4d85a8 frank zago 2022-06-15  70  {
f33ee28d4d85a8 frank zago 2022-06-15  71  	mfd_remove_devices(&usb_if->dev);
f33ee28d4d85a8 frank zago 2022-06-15  72  }
f33ee28d4d85a8 frank zago 2022-06-15  73  
f33ee28d4d85a8 frank zago 2022-06-15  74  static const struct usb_device_id ch341_usb_table[] = {
f33ee28d4d85a8 frank zago 2022-06-15  75  	{ USB_DEVICE(0x1a86, 0x5512) },
f33ee28d4d85a8 frank zago 2022-06-15  76  	{ }
f33ee28d4d85a8 frank zago 2022-06-15  77  };
f33ee28d4d85a8 frank zago 2022-06-15  78  MODULE_DEVICE_TABLE(usb, ch341_usb_table);
f33ee28d4d85a8 frank zago 2022-06-15  79  
f33ee28d4d85a8 frank zago 2022-06-15  80  static struct usb_driver ch341_usb_driver = {
f33ee28d4d85a8 frank zago 2022-06-15  81  	.name       = "ch341-mfd",
f33ee28d4d85a8 frank zago 2022-06-15  82  	.id_table   = ch341_usb_table,
f33ee28d4d85a8 frank zago 2022-06-15  83  	.probe      = ch341_usb_probe,
f33ee28d4d85a8 frank zago 2022-06-15  84  	.disconnect = ch341_usb_disconnect,
f33ee28d4d85a8 frank zago 2022-06-15  85  };
f33ee28d4d85a8 frank zago 2022-06-15 @86  module_usb_driver(ch341_usb_driver);
f33ee28d4d85a8 frank zago 2022-06-15  87  

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

Re: [PATCH v6 3/4] i2c: ch341: add I2C MFD cell driver for the CH341

[kernel test robot]

Hi frank,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on lee-mfd/for-mfd-next]
[also build test ERROR on brgl/gpio/for-next wsa/i2c/for-next linus/master v5.19-rc2 next-20220616]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/intel-lab-lkp/linux/commits/frank-zago/add-driver-for-the-WCH-CH341-in-I2C-GPIO-mode/20220616-094113
base:   https://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd.git for-mfd-next
config: arc-buildonly-randconfig-r004-20220616 (https://download.01.org/0day-ci/archive/20220616/202206161938.BiOHSAOi-lkp@intel.com/config)
compiler: arc-elf-gcc (GCC) 11.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/46c68aee86d34ee630272146a73ad7c3147bb094
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review frank-zago/add-driver-for-the-WCH-CH341-in-I2C-GPIO-mode/20220616-094113
        git checkout 46c68aee86d34ee630272146a73ad7c3147bb094
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=arc SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>, old ones prefixed by <<):

>> ERROR: modpost: "usb_bulk_msg" [drivers/i2c/busses/i2c-ch341.ko] undefined!
>> ERROR: modpost: "usb_deregister" [drivers/mfd/ch341-core.ko] undefined!
>> ERROR: modpost: "usb_register_driver" [drivers/mfd/ch341-core.ko] undefined!
>> ERROR: modpost: "usb_find_common_endpoints" [drivers/mfd/ch341-core.ko] undefined!

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for MFD_CH341
   Depends on HAS_IOMEM && USB
   Selected by
   - I2C_CH341 && I2C && HAS_IOMEM

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

Re: [PATCH v6 2/4] gpio: ch341: add GPIO MFD cell driver for the CH341

[Linus Walleij]

On Thu, Jun 16, 2022 at 3:38 AM frank zago <frank@zago.net> wrote:

> The GPIO interface offers 16 GPIOs. 6 are read/write, and 10 are
> read-only.
>
> Signed-off-by: frank zago <frank@zago.net>

Acked-by: Linus Walleij <linus.walleij@linaro.org>

Please preserve my ACK on subsequent postings, USB changes does
not concern me, I trust Johan to review those for you.

Yours,
Linus Walleij

Re: [PATCH v6 0/4] add driver for the WCH CH341 in I2C/GPIO mode

[Johan Hovold]

On Wed, Jun 15, 2022 at 08:37:43PM -0500, frank zago wrote:
> The CH341 is a multifunction chip, presenting 3 different USB PID. One
> of these functions is for I2C/SPI/GPIO. This new set of drivers will
> manage I2C and GPIO.
> 
> Changes from v5:
> Addressed reviewers' comments.

Please be more specific in your changelogs. This essentially just says
"changed stuff".

> Better handling of 0-bytes i2c commands
> Use of better USB API.

What does this even mean?

Johan

Re: [PATCH v6 2/4] gpio: ch341: add GPIO MFD cell driver for the CH341

[Johan Hovold]

On Wed, Jun 15, 2022 at 08:37:45PM -0500, frank zago wrote:
> The GPIO interface offers 16 GPIOs. 6 are read/write, and 10 are
> read-only.

Please mention the single interrupt line here too.

> Signed-off-by: frank zago <frank@zago.net>
> ---
>  MAINTAINERS               |   1 +
>  drivers/gpio/Kconfig      |  10 +
>  drivers/gpio/Makefile     |   1 +
>  drivers/gpio/gpio-ch341.c | 385 ++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/ch341.h |   8 +
>  5 files changed, 405 insertions(+)
>  create mode 100644 drivers/gpio/gpio-ch341.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 628eeaa9bf68..8b93f6192704 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21479,6 +21479,7 @@ WINCHIPHEAD CH341 I2C/GPIO MFD DRIVER
>  M:	Frank Zago <frank@zago.net>
>  L:	linux-usb@vger.kernel.org
>  S:	Maintained
> +F:	drivers/gpio/gpio-ch341.c
>  F:	drivers/mfd/ch341-core.c
>  F:	include/linux/mfd/ch341.h
>  
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index b01961999ced..473b6e7226ca 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -1653,6 +1653,16 @@ endmenu
>  menu "USB GPIO expanders"
>  	depends on USB
>  
> +config GPIO_CH341
> +	tristate "CH341 USB to GPIO support"
> +	select MFD_CH341

This should be "depends" (for all subdrivers).

> +	help
> +	  If you say yes to this option, GPIO support will be included for the
> +	  WCH CH341, a USB to I2C/SPI/GPIO interface.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called gpio-ch341.
> +
>  config GPIO_VIPERBOARD
>  	tristate "Viperboard GPIO a & b support"
>  	depends on MFD_VIPERBOARD

[ and other MFD drivers as you see here ]

> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 14352f6dfe8e..beef802cbfb1 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -44,6 +44,7 @@ obj-$(CONFIG_GPIO_BD9571MWV)		+= gpio-bd9571mwv.o
>  obj-$(CONFIG_GPIO_BRCMSTB)		+= gpio-brcmstb.o
>  obj-$(CONFIG_GPIO_BT8XX)		+= gpio-bt8xx.o
>  obj-$(CONFIG_GPIO_CADENCE)		+= gpio-cadence.o
> +obj-$(CONFIG_GPIO_CH341)		+= gpio-ch341.o
>  obj-$(CONFIG_GPIO_CLPS711X)		+= gpio-clps711x.o
>  obj-$(CONFIG_GPIO_SNPS_CREG)		+= gpio-creg-snps.o
>  obj-$(CONFIG_GPIO_CRYSTAL_COVE)		+= gpio-crystalcove.o
> diff --git a/drivers/gpio/gpio-ch341.c b/drivers/gpio/gpio-ch341.c
> new file mode 100644
> index 000000000000..233dfe1f2ae8
> --- /dev/null
> +++ b/drivers/gpio/gpio-ch341.c
> @@ -0,0 +1,385 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * GPIO cell driver for the CH341A and CH341B chips.
> + *
> + * Copyright 2022, Frank Zago

How about using a unified format for these lines?

> + * Copyright (c) 2017 Gunar Schorcht (gunar@schorcht.net)
> + * Copyright (c) 2016 Tse Lun Bien
> + * Copyright (c) 2014 Marco Gittler
> + * Copyright (c) 2006-2007 Till Harbaum (Till@Harbaum.org)
> + */
> +
> +/*
> + * Notes.
> + *
> + * For the CH341, 0=IN, 1=OUT, but for the GPIO subsystem, 1=IN and
> + * 0=OUT. Translation happens in a couple places.
> + */
> +
> +#include <linux/gpio/driver.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/ch341.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/types.h>
> +#include <linux/usb.h>
> +
> +#define CH341_GPIO_NUM_PINS         16    /* Number of GPIO pins */
> +
> +/* GPIO chip commands */
> +#define CH341_PARA_CMD_STS          0xA0  /* Get pins status */
> +#define CH341_CMD_UIO_STREAM        0xAB  /* pin IO stream command */
> +
> +#define CH341_CMD_UIO_STM_OUT       0x80  /* pin IO interface OUT command (D0~D5) */
> +#define CH341_CMD_UIO_STM_DIR       0x40  /* pin IO interface DIR command (D0~D5) */
> +#define CH341_CMD_UIO_STM_END       0x20  /* pin IO interface END command */
> +
> +#define CH341_USB_MAX_INTR_SIZE 8
> +
> +struct ch341_gpio {
> +	struct gpio_chip gpio;
> +	struct mutex gpio_lock;
> +	u16 gpio_dir;		/* 1 bit per pin, 0=IN, 1=OUT. */
> +	u16 gpio_last_read;	/* last GPIO values read */
> +	u16 gpio_last_written;	/* last GPIO values written */
> +	union {
> +		u8 gpio_buf[SEG_SIZE];
> +		__le16 gpio_buf_status;
> +	};

This one should be allocated separately from the containing structure
since it may be mapped for DMA.

> +
> +	struct urb *irq_urb;
> +	struct usb_anchor irq_urb_out;
> +	u8 irq_buf[CH341_USB_MAX_INTR_SIZE];

Same here.

You may need to check other drivers too.

> +	struct irq_chip irq_chip;
> +
> +	struct ch341_ddata *ddata;
> +};
> +
> +/*
> + * Masks to describe the 16 GPIOs. Pins D0 to D5 (mapped to GPIOs 0 to
> + * 5) can do input/output, but the other pins are input-only.
> + */
> +static const u16 pin_can_output = 0b111111;
> +
> +/* Only GPIO 10 (INT# line) has hardware interrupt */
> +#define CH341_GPIO_INT_LINE 10
> +
> +/* Send a command and get a reply if requested */
> +static int gpio_transfer(struct ch341_gpio *dev, int out_len, int in_len)
> +{
> +	struct ch341_ddata *ddata = dev->ddata;
> +	int actual;
> +	int ret;
> +
> +	mutex_lock(&ddata->usb_lock);
> +
> +	ret = usb_bulk_msg(ddata->usb_dev,
> +			   usb_sndbulkpipe(ddata->usb_dev, ddata->ep_out),
> +			   dev->gpio_buf, out_len,
> +			   &actual, DEFAULT_TIMEOUT_MS);
> +	if (ret < 0)
> +		goto out_unlock;
> +
> +	if (in_len == 0)
> +		goto out_unlock;
> +
> +	ret = usb_bulk_msg(ddata->usb_dev,
> +			   usb_rcvbulkpipe(ddata->usb_dev, ddata->ep_in),
> +			   dev->gpio_buf, SEG_SIZE, &actual, DEFAULT_TIMEOUT_MS);
> +
> +out_unlock:
> +	mutex_unlock(&ddata->usb_lock);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	return actual;
> +}

> +static void ch341_complete_intr_urb(struct urb *urb)
> +{
> +	struct ch341_gpio *dev = urb->context;
> +	int ret;
> +
> +	if (urb->status) {
> +		usb_unanchor_urb(dev->irq_urb);

Again, why is this here?

> +	} else {
> +		/*
> +		 * Data is 8 bytes. Byte 0 might be the length of
> +		 * significant data, which is 3 more bytes. Bytes 1
> +		 * and 2, and possibly 3, are the pin status. The byte
> +		 * order is different than for the GET_STATUS
> +		 * command. Byte 1 is GPIOs 8 to 15, and byte 2 is
> +		 * GPIOs 0 to 7.
> +		 */
> +
> +		handle_nested_irq(irq_find_mapping(dev->gpio.irq.domain,
> +						   CH341_GPIO_INT_LINE));
> +
> +		ret = usb_submit_urb(dev->irq_urb, GFP_ATOMIC);
> +		if (ret)
> +			usb_unanchor_urb(dev->irq_urb);

Ditto. This isn't how anchors are used.

> +	}
> +}
> +
> +static int ch341_gpio_irq_set_type(struct irq_data *data, unsigned int flow_type)
> +{
> +	const unsigned long offset = irqd_to_hwirq(data);
> +
> +	if (offset != CH341_GPIO_INT_LINE || flow_type != IRQ_TYPE_EDGE_RISING)
> +		return -EINVAL;

Ok, I missed this check before, sorry. So you do have a single interrupt
line.

You should probably add a comment in the enable() callback since this is
easy to miss.

> +
> +	return 0;
> +}
> +
> +static void ch341_gpio_irq_enable(struct irq_data *data)
> +{
> +	struct ch341_gpio *dev = irq_data_get_irq_chip_data(data);
> +	int ret;
> +
> +	/*
> +	 * The URB might have just been unlinked in
> +	 * ch341_gpio_irq_disable, but the completion handler hasn't
> +	 * been called yet.
> +	 */
> +	if (!usb_wait_anchor_empty_timeout(&dev->irq_urb_out, 5000))
> +		usb_kill_anchored_urbs(&dev->irq_urb_out);

You cannot sleep in this function.

> +
> +	usb_anchor_urb(dev->irq_urb, &dev->irq_urb_out);
> +	ret = usb_submit_urb(dev->irq_urb, GFP_KERNEL);
> +	if (ret)
> +		usb_unanchor_urb(dev->irq_urb);
> +}
> +
> +static void ch341_gpio_irq_disable(struct irq_data *data)
> +{
> +	struct ch341_gpio *dev = irq_data_get_irq_chip_data(data);
> +
> +	usb_unlink_urb(dev->irq_urb);
> +}
> +
> +static int ch341_gpio_remove(struct platform_device *pdev)
> +{
> +	struct ch341_gpio *dev = platform_get_drvdata(pdev);
> +
> +	usb_kill_anchored_urbs(&dev->irq_urb_out);

Again, this is racy as the gpio chip is still registered. And you don't
need an anchor to stop a single URB.

> +	gpiochip_remove(&dev->gpio);
> +	usb_free_urb(dev->irq_urb);
> +
> +	return 0;
> +}
> +
> +static const struct irq_chip ch341_irqchip = {
> +	.name = "CH341",
> +	.irq_set_type = ch341_gpio_irq_set_type,
> +	.irq_enable = ch341_gpio_irq_enable,
> +	.irq_disable = ch341_gpio_irq_disable,
> +	.flags = IRQCHIP_IMMUTABLE,
> +	GPIOCHIP_IRQ_RESOURCE_HELPERS,
> +};
> +
> +static int ch341_gpio_probe(struct platform_device *pdev)
> +{
> +	struct ch341_ddata *ddata = dev_get_drvdata(pdev->dev.parent);
> +	struct gpio_irq_chip *girq;
> +	struct ch341_gpio *dev;
> +	struct gpio_chip *gpio;
> +	int ret;
> +
> +	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
> +	if (dev == NULL)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, dev);
> +	dev->ddata = ddata;
> +	mutex_init(&dev->gpio_lock);
> +
> +	gpio = &dev->gpio;
> +	gpio->label = dev_name(&pdev->dev);
> +	gpio->parent = &pdev->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->base = -1;
> +	gpio->ngpio = CH341_GPIO_NUM_PINS;
> +	gpio->can_sleep = true;
> +
> +	girq = &gpio->irq;
> +	gpio_irq_chip_set_chip(girq, &ch341_irqchip);
> +	girq->handler = handle_simple_irq;
> +	girq->default_type = IRQ_TYPE_NONE;
> +
> +	/* Create an URB for handling interrupt */
> +	dev->irq_urb = usb_alloc_urb(0, GFP_KERNEL);
> +	if (!dev->irq_urb)
> +		return dev_err_probe(&pdev->dev, -ENOMEM, "Cannot allocate the int URB\n");

This isn't how dev_err_probe() is used.

And allocation failures are already logged so just return -ENOMEM here.

> +
> +	usb_fill_int_urb(dev->irq_urb, ddata->usb_dev,
> +			 usb_rcvintpipe(ddata->usb_dev, ddata->ep_intr),
> +			 dev->irq_buf, CH341_USB_MAX_INTR_SIZE,
> +			 ch341_complete_intr_urb, dev, ddata->ep_intr_interval);
> +
> +	init_usb_anchor(&dev->irq_urb_out);
> +
> +	ret = gpiochip_add_data(gpio, dev);
> +	if (ret) {
> +		ret = dev_err_probe(&pdev->dev, ret, "Could not add GPIO\n");
> +		goto release_urb;
> +	}
> +
> +	return 0;
> +
> +release_urb:
> +	usb_free_urb(dev->irq_urb);
> +
> +	return ret;
> +}

Johan

Re: [PATCH v6 2/4] gpio: ch341: add GPIO MFD cell driver for the CH341

[Andy Shevchenko]

On Mon, Jun 20, 2022 at 12:26 PM Johan Hovold <johan@kernel.org> wrote:
> On Wed, Jun 15, 2022 at 08:37:45PM -0500, frank zago wrote:

...

> > +     /* Create an URB for handling interrupt */
> > +     dev->irq_urb = usb_alloc_urb(0, GFP_KERNEL);
> > +     if (!dev->irq_urb)
> > +             return dev_err_probe(&pdev->dev, -ENOMEM, "Cannot allocate the int URB\n");
>
> This isn't how dev_err_probe() is used.

While I agree on the below comment, what does this imply?

> And allocation failures are already logged so just return -ENOMEM here.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 2/4] gpio: ch341: add GPIO MFD cell driver for the CH341

[Johan Hovold]

On Mon, Jun 20, 2022 at 06:08:19PM +0200, Andy Shevchenko wrote:
> On Mon, Jun 20, 2022 at 12:26 PM Johan Hovold <johan@kernel.org> wrote:
> > On Wed, Jun 15, 2022 at 08:37:45PM -0500, frank zago wrote:
> 
> ...
> 
> > > +     /* Create an URB for handling interrupt */
> > > +     dev->irq_urb = usb_alloc_urb(0, GFP_KERNEL);
> > > +     if (!dev->irq_urb)
> > > +             return dev_err_probe(&pdev->dev, -ENOMEM, "Cannot allocate the int URB\n");
> >
> > This isn't how dev_err_probe() is used.
> 
> While I agree on the below comment, what does this imply?

That you should only use dev_err_probe() to handle -EPROBE_DEFER. That's
what it is was added for, documented as, and it is what the
implementation still tells you.

I see now that there has recently been some mission creep:

	7065f92255bb ("driver core: Clarify that dev_err_probe() is OK even w/out -EPROBE_DEFER")

I'm not sure I agree with that, but fortunately we don't need to have
that debate in this case due to the below.
 
> > And allocation failures are already logged so just return -ENOMEM here.

Johan

Re: [PATCH v6 1/4] mfd: ch341: add core driver for the WCH CH341 in I2C/SPI/GPIO mode

[Lee Jones]

USB review please.

> The CH341 is a multifunction chip, presenting 3 different USB PID. One
> 
> of these functions is for I2C/SPI/GPIO. This new set of drivers will
> manage I2C and GPIO.
> 
> Signed-off-by: frank zago <frank@zago.net>
> ---
>  MAINTAINERS               |  7 +++
>  drivers/mfd/Kconfig       | 10 +++++
>  drivers/mfd/Makefile      |  1 +
>  drivers/mfd/ch341-core.c  | 90 +++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/ch341.h | 18 ++++++++
>  5 files changed, 126 insertions(+)
>  create mode 100644 drivers/mfd/ch341-core.c
>  create mode 100644 include/linux/mfd/ch341.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 43d3d07afccd..628eeaa9bf68 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21475,6 +21475,13 @@ M:	David Härdeman <david@hardeman.nu>
>  S:	Maintained
>  F:	drivers/media/rc/winbond-cir.c
>  
> +WINCHIPHEAD CH341 I2C/GPIO MFD DRIVER
> +M:	Frank Zago <frank@zago.net>
> +L:	linux-usb@vger.kernel.org
> +S:	Maintained
> +F:	drivers/mfd/ch341-core.c
> +F:	include/linux/mfd/ch341.h
> +
>  WINSYSTEMS EBC-C384 WATCHDOG DRIVER
>  M:	William Breathitt Gray <vilhelm.gray@gmail.com>
>  L:	linux-watchdog@vger.kernel.org
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 3b59456f5545..893acc821a42 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -1784,6 +1784,16 @@ config MFD_LOCHNAGAR
>  	help
>  	  Support for Cirrus Logic Lochnagar audio development board.
>  
> +config MFD_CH341
> +	tristate "WinChipHead CH341 in I2C/SPI/GPIO mode"
> +	depends on USB
> +	help
> +	  If you say yes to this option, support for the CH341 series
> +	  of chips, running in I2C/SPI/GPIO mode will be included.
> +
> +	  This driver can also be built as a module.  If so, the
> +	  module will be called ch341-core.
> +
>  config MFD_ARIZONA
>  	select REGMAP
>  	select REGMAP_IRQ
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 858cacf659d6..fd615ab3929f 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -13,6 +13,7 @@ obj-$(CONFIG_MFD_ASIC3)		+= asic3.o tmio_core.o
>  obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835-pm.o
>  obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
>  obj-$(CONFIG_MFD_BD9571MWV)	+= bd9571mwv.o
> +obj-$(CONFIG_MFD_CH341)		+= ch341-core.o
>  obj-$(CONFIG_MFD_CROS_EC_DEV)	+= cros_ec_dev.o
>  obj-$(CONFIG_MFD_ENE_KB3930)	+= ene-kb3930.o
>  obj-$(CONFIG_MFD_EXYNOS_LPASS)	+= exynos-lpass.o
> diff --git a/drivers/mfd/ch341-core.c b/drivers/mfd/ch341-core.c
> new file mode 100644
> index 000000000000..f08a67dd6074
> --- /dev/null
> +++ b/drivers/mfd/ch341-core.c
> @@ -0,0 +1,90 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Core driver for the CH341A, CH341B and CH341T in I2C/SPI/GPIO
> + * mode. There are cell drivers available for I2C and GPIO. SPI is not
> + * yet supported.
> + *
> + * Copyright 2022, Frank Zago
> + * Copyright (c) 2017 Gunar Schorcht (gunar@schorcht.net)
> + * Copyright (c) 2016 Tse Lun Bien
> + * Copyright (c) 2014 Marco Gittler
> + * Copyright (c) 2006-2007 Till Harbaum (Till@Harbaum.org)
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/mfd/ch341.h>
> +#include <linux/mfd/core.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/usb.h>
> +
> +static const struct mfd_cell ch341_devs[] = {
> +	{
> +		.name = "ch341-gpio",
> +	},
> +	{
> +		.name = "ch341-i2c",
> +	},
> +};
> +
> +static int ch341_usb_probe(struct usb_interface *iface,
> +			   const struct usb_device_id *usb_id)
> +{
> +	struct usb_endpoint_descriptor *bulk_out;
> +	struct usb_endpoint_descriptor *bulk_in;
> +	struct usb_endpoint_descriptor *intr_in;
> +	struct ch341_ddata *ddata;
> +	int ret;
> +
> +	ddata = devm_kzalloc(&iface->dev, sizeof(*ddata), GFP_KERNEL);
> +	if (!ddata)
> +		return -ENOMEM;
> +
> +	ddata->usb_dev = interface_to_usbdev(iface);
> +	mutex_init(&ddata->usb_lock);
> +
> +	ret = usb_find_common_endpoints(iface->cur_altsetting, &bulk_in,
> +					&bulk_out, &intr_in, NULL);
> +	if (ret) {
> +		dev_err(&iface->dev, "Could not find all endpoints\n");
> +		return -ENODEV;
> +	}
> +
> +	ddata->ep_in = bulk_in->bEndpointAddress;
> +	ddata->ep_out = bulk_out->bEndpointAddress;
> +	ddata->ep_intr = intr_in->bEndpointAddress;
> +	ddata->ep_intr_interval = intr_in->bInterval;
> +
> +	usb_set_intfdata(iface, ddata);
> +
> +	ret = mfd_add_devices(&iface->dev, PLATFORM_DEVID_AUTO, ch341_devs,
> +			      ARRAY_SIZE(ch341_devs), NULL, 0, NULL);
> +	if (ret)
> +		return dev_err_probe(&iface->dev, ret,
> +				     "Failed to register child devices\n");
> +
> +	return 0;
> +}
> +
> +static void ch341_usb_disconnect(struct usb_interface *usb_if)
> +{
> +	mfd_remove_devices(&usb_if->dev);
> +}
> +
> +static const struct usb_device_id ch341_usb_table[] = {
> +	{ USB_DEVICE(0x1a86, 0x5512) },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(usb, ch341_usb_table);
> +
> +static struct usb_driver ch341_usb_driver = {
> +	.name       = "ch341-mfd",
> +	.id_table   = ch341_usb_table,
> +	.probe      = ch341_usb_probe,
> +	.disconnect = ch341_usb_disconnect,
> +};
> +module_usb_driver(ch341_usb_driver);
> +
> +MODULE_AUTHOR("Frank Zago <frank@zago.net>");
> +MODULE_DESCRIPTION("CH341 USB to I2C/SPI/GPIO adapter");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/mfd/ch341.h b/include/linux/mfd/ch341.h
> new file mode 100644
> index 000000000000..44f5da0720bd
> --- /dev/null
> +++ b/include/linux/mfd/ch341.h
> @@ -0,0 +1,18 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Definitions for the CH341 driver */
> +
> +#include <linux/mutex.h>
> +#include <linux/types.h>
> +
> +struct usb_device;
> +struct usb_interface;
> +
> +struct ch341_ddata {
> +	struct usb_device *usb_dev;
> +	struct mutex usb_lock;
> +
> +	int ep_in;
> +	int ep_out;
> +	int ep_intr;
> +	u8 ep_intr_interval;
> +};

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: [PATCH v6 1/4] mfd: ch341: add core driver for the WCH CH341 in I2C/SPI/GPIO mode

[Greg Kroah-Hartman]

On Mon, Jun 27, 2022 at 03:04:32PM +0100, Lee Jones wrote:
> USB review please.
> 
> > The CH341 is a multifunction chip, presenting 3 different USB PID. One
> > 
> > of these functions is for I2C/SPI/GPIO. This new set of drivers will
> > manage I2C and GPIO.
> > 
> > Signed-off-by: frank zago <frank@zago.net>
> > ---
> >  MAINTAINERS               |  7 +++
> >  drivers/mfd/Kconfig       | 10 +++++
> >  drivers/mfd/Makefile      |  1 +
> >  drivers/mfd/ch341-core.c  | 90 +++++++++++++++++++++++++++++++++++++++
> >  include/linux/mfd/ch341.h | 18 ++++++++
> >  5 files changed, 126 insertions(+)
> >  create mode 100644 drivers/mfd/ch341-core.c
> >  create mode 100644 include/linux/mfd/ch341.h
> > 
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 43d3d07afccd..628eeaa9bf68 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -21475,6 +21475,13 @@ M:	David Härdeman <david@hardeman.nu>
> >  S:	Maintained
> >  F:	drivers/media/rc/winbond-cir.c
> >  
> > +WINCHIPHEAD CH341 I2C/GPIO MFD DRIVER
> > +M:	Frank Zago <frank@zago.net>
> > +L:	linux-usb@vger.kernel.org
> > +S:	Maintained
> > +F:	drivers/mfd/ch341-core.c
> > +F:	include/linux/mfd/ch341.h
> > +
> >  WINSYSTEMS EBC-C384 WATCHDOG DRIVER
> >  M:	William Breathitt Gray <vilhelm.gray@gmail.com>
> >  L:	linux-watchdog@vger.kernel.org
> > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> > index 3b59456f5545..893acc821a42 100644
> > --- a/drivers/mfd/Kconfig
> > +++ b/drivers/mfd/Kconfig
> > @@ -1784,6 +1784,16 @@ config MFD_LOCHNAGAR
> >  	help
> >  	  Support for Cirrus Logic Lochnagar audio development board.
> >  
> > +config MFD_CH341
> > +	tristate "WinChipHead CH341 in I2C/SPI/GPIO mode"
> > +	depends on USB
> > +	help
> > +	  If you say yes to this option, support for the CH341 series
> > +	  of chips, running in I2C/SPI/GPIO mode will be included.
> > +
> > +	  This driver can also be built as a module.  If so, the
> > +	  module will be called ch341-core.
> > +
> >  config MFD_ARIZONA
> >  	select REGMAP
> >  	select REGMAP_IRQ
> > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> > index 858cacf659d6..fd615ab3929f 100644
> > --- a/drivers/mfd/Makefile
> > +++ b/drivers/mfd/Makefile
> > @@ -13,6 +13,7 @@ obj-$(CONFIG_MFD_ASIC3)		+= asic3.o tmio_core.o
> >  obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835-pm.o
> >  obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
> >  obj-$(CONFIG_MFD_BD9571MWV)	+= bd9571mwv.o
> > +obj-$(CONFIG_MFD_CH341)		+= ch341-core.o
> >  obj-$(CONFIG_MFD_CROS_EC_DEV)	+= cros_ec_dev.o
> >  obj-$(CONFIG_MFD_ENE_KB3930)	+= ene-kb3930.o
> >  obj-$(CONFIG_MFD_EXYNOS_LPASS)	+= exynos-lpass.o
> > diff --git a/drivers/mfd/ch341-core.c b/drivers/mfd/ch341-core.c
> > new file mode 100644
> > index 000000000000..f08a67dd6074
> > --- /dev/null
> > +++ b/drivers/mfd/ch341-core.c
> > @@ -0,0 +1,90 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Core driver for the CH341A, CH341B and CH341T in I2C/SPI/GPIO
> > + * mode. There are cell drivers available for I2C and GPIO. SPI is not
> > + * yet supported.
> > + *
> > + * Copyright 2022, Frank Zago
> > + * Copyright (c) 2017 Gunar Schorcht (gunar@schorcht.net)
> > + * Copyright (c) 2016 Tse Lun Bien
> > + * Copyright (c) 2014 Marco Gittler
> > + * Copyright (c) 2006-2007 Till Harbaum (Till@Harbaum.org)
> > + */
> > +
> > +#include <linux/kernel.h>
> > +#include <linux/mfd/ch341.h>
> > +#include <linux/mfd/core.h>
> > +#include <linux/module.h>
> > +#include <linux/slab.h>
> > +#include <linux/usb.h>
> > +
> > +static const struct mfd_cell ch341_devs[] = {
> > +	{
> > +		.name = "ch341-gpio",
> > +	},
> > +	{
> > +		.name = "ch341-i2c",
> > +	},
> > +};
> > +
> > +static int ch341_usb_probe(struct usb_interface *iface,
> > +			   const struct usb_device_id *usb_id)
> > +{
> > +	struct usb_endpoint_descriptor *bulk_out;
> > +	struct usb_endpoint_descriptor *bulk_in;
> > +	struct usb_endpoint_descriptor *intr_in;
> > +	struct ch341_ddata *ddata;
> > +	int ret;
> > +
> > +	ddata = devm_kzalloc(&iface->dev, sizeof(*ddata), GFP_KERNEL);
> > +	if (!ddata)
> > +		return -ENOMEM;
> > +
> > +	ddata->usb_dev = interface_to_usbdev(iface);
> > +	mutex_init(&ddata->usb_lock);
> > +
> > +	ret = usb_find_common_endpoints(iface->cur_altsetting, &bulk_in,
> > +					&bulk_out, &intr_in, NULL);
> > +	if (ret) {
> > +		dev_err(&iface->dev, "Could not find all endpoints\n");
> > +		return -ENODEV;
> > +	}
> > +
> > +	ddata->ep_in = bulk_in->bEndpointAddress;
> > +	ddata->ep_out = bulk_out->bEndpointAddress;
> > +	ddata->ep_intr = intr_in->bEndpointAddress;
> > +	ddata->ep_intr_interval = intr_in->bInterval;
> > +
> > +	usb_set_intfdata(iface, ddata);
> > +
> > +	ret = mfd_add_devices(&iface->dev, PLATFORM_DEVID_AUTO, ch341_devs,
> > +			      ARRAY_SIZE(ch341_devs), NULL, 0, NULL);
> > +	if (ret)
> > +		return dev_err_probe(&iface->dev, ret,
> > +				     "Failed to register child devices\n");
> > +
> > +	return 0;
> > +}
> > +
> > +static void ch341_usb_disconnect(struct usb_interface *usb_if)
> > +{
> > +	mfd_remove_devices(&usb_if->dev);
> > +}
> > +
> > +static const struct usb_device_id ch341_usb_table[] = {
> > +	{ USB_DEVICE(0x1a86, 0x5512) },
> > +	{ }
> > +};
> > +MODULE_DEVICE_TABLE(usb, ch341_usb_table);
> > +
> > +static struct usb_driver ch341_usb_driver = {
> > +	.name       = "ch341-mfd",
> > +	.id_table   = ch341_usb_table,
> > +	.probe      = ch341_usb_probe,
> > +	.disconnect = ch341_usb_disconnect,
> > +};
> > +module_usb_driver(ch341_usb_driver);
> > +
> > +MODULE_AUTHOR("Frank Zago <frank@zago.net>");
> > +MODULE_DESCRIPTION("CH341 USB to I2C/SPI/GPIO adapter");
> > +MODULE_LICENSE("GPL");
> > diff --git a/include/linux/mfd/ch341.h b/include/linux/mfd/ch341.h
> > new file mode 100644
> > index 000000000000..44f5da0720bd
> > --- /dev/null
> > +++ b/include/linux/mfd/ch341.h
> > @@ -0,0 +1,18 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/* Definitions for the CH341 driver */
> > +
> > +#include <linux/mutex.h>
> > +#include <linux/types.h>
> > +
> > +struct usb_device;
> > +struct usb_interface;
> > +
> > +struct ch341_ddata {
> > +	struct usb_device *usb_dev;
> > +	struct mutex usb_lock;
> > +
> > +	int ep_in;
> > +	int ep_out;
> > +	int ep_intr;
> > +	u8 ep_intr_interval;
> > +};


Looks sane enough, but doesn't actually do any USB data transfers, maybe
that happens somewhere else...

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Re: [PATCH v6 1/4] mfd: ch341: add core driver for the WCH CH341 in I2C/SPI/GPIO mode

[Lee Jones]

On Mon, 27 Jun 2022, Greg Kroah-Hartman wrote:

> On Mon, Jun 27, 2022 at 03:04:32PM +0100, Lee Jones wrote:
> > USB review please.
> > 
> > > The CH341 is a multifunction chip, presenting 3 different USB PID. One
> > > 
> > > of these functions is for I2C/SPI/GPIO. This new set of drivers will
> > > manage I2C and GPIO.
> > > 
> > > Signed-off-by: frank zago <frank@zago.net>
> > > ---
> > >  MAINTAINERS               |  7 +++
> > >  drivers/mfd/Kconfig       | 10 +++++
> > >  drivers/mfd/Makefile      |  1 +
> > >  drivers/mfd/ch341-core.c  | 90 +++++++++++++++++++++++++++++++++++++++
> > >  include/linux/mfd/ch341.h | 18 ++++++++
> > >  5 files changed, 126 insertions(+)
> > >  create mode 100644 drivers/mfd/ch341-core.c
> > >  create mode 100644 include/linux/mfd/ch341.h
> > > 
> > > diff --git a/MAINTAINERS b/MAINTAINERS
> > > index 43d3d07afccd..628eeaa9bf68 100644
> > > --- a/MAINTAINERS
> > > +++ b/MAINTAINERS
> > > @@ -21475,6 +21475,13 @@ M:	David Härdeman <david@hardeman.nu>
> > >  S:	Maintained
> > >  F:	drivers/media/rc/winbond-cir.c
> > >  
> > > +WINCHIPHEAD CH341 I2C/GPIO MFD DRIVER
> > > +M:	Frank Zago <frank@zago.net>
> > > +L:	linux-usb@vger.kernel.org
> > > +S:	Maintained
> > > +F:	drivers/mfd/ch341-core.c
> > > +F:	include/linux/mfd/ch341.h
> > > +
> > >  WINSYSTEMS EBC-C384 WATCHDOG DRIVER
> > >  M:	William Breathitt Gray <vilhelm.gray@gmail.com>
> > >  L:	linux-watchdog@vger.kernel.org
> > > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> > > index 3b59456f5545..893acc821a42 100644
> > > --- a/drivers/mfd/Kconfig
> > > +++ b/drivers/mfd/Kconfig
> > > @@ -1784,6 +1784,16 @@ config MFD_LOCHNAGAR
> > >  	help
> > >  	  Support for Cirrus Logic Lochnagar audio development board.
> > >  
> > > +config MFD_CH341
> > > +	tristate "WinChipHead CH341 in I2C/SPI/GPIO mode"
> > > +	depends on USB
> > > +	help
> > > +	  If you say yes to this option, support for the CH341 series
> > > +	  of chips, running in I2C/SPI/GPIO mode will be included.
> > > +
> > > +	  This driver can also be built as a module.  If so, the
> > > +	  module will be called ch341-core.
> > > +
> > >  config MFD_ARIZONA
> > >  	select REGMAP
> > >  	select REGMAP_IRQ
> > > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> > > index 858cacf659d6..fd615ab3929f 100644
> > > --- a/drivers/mfd/Makefile
> > > +++ b/drivers/mfd/Makefile
> > > @@ -13,6 +13,7 @@ obj-$(CONFIG_MFD_ASIC3)		+= asic3.o tmio_core.o
> > >  obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835-pm.o
> > >  obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
> > >  obj-$(CONFIG_MFD_BD9571MWV)	+= bd9571mwv.o
> > > +obj-$(CONFIG_MFD_CH341)		+= ch341-core.o
> > >  obj-$(CONFIG_MFD_CROS_EC_DEV)	+= cros_ec_dev.o
> > >  obj-$(CONFIG_MFD_ENE_KB3930)	+= ene-kb3930.o
> > >  obj-$(CONFIG_MFD_EXYNOS_LPASS)	+= exynos-lpass.o
> > > diff --git a/drivers/mfd/ch341-core.c b/drivers/mfd/ch341-core.c
> > > new file mode 100644
> > > index 000000000000..f08a67dd6074
> > > --- /dev/null
> > > +++ b/drivers/mfd/ch341-core.c
> > > @@ -0,0 +1,90 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * Core driver for the CH341A, CH341B and CH341T in I2C/SPI/GPIO
> > > + * mode. There are cell drivers available for I2C and GPIO. SPI is not
> > > + * yet supported.
> > > + *
> > > + * Copyright 2022, Frank Zago
> > > + * Copyright (c) 2017 Gunar Schorcht (gunar@schorcht.net)
> > > + * Copyright (c) 2016 Tse Lun Bien
> > > + * Copyright (c) 2014 Marco Gittler
> > > + * Copyright (c) 2006-2007 Till Harbaum (Till@Harbaum.org)
> > > + */
> > > +
> > > +#include <linux/kernel.h>
> > > +#include <linux/mfd/ch341.h>
> > > +#include <linux/mfd/core.h>
> > > +#include <linux/module.h>
> > > +#include <linux/slab.h>
> > > +#include <linux/usb.h>
> > > +
> > > +static const struct mfd_cell ch341_devs[] = {
> > > +	{
> > > +		.name = "ch341-gpio",
> > > +	},
> > > +	{
> > > +		.name = "ch341-i2c",
> > > +	},
> > > +};
> > > +
> > > +static int ch341_usb_probe(struct usb_interface *iface,
> > > +			   const struct usb_device_id *usb_id)
> > > +{
> > > +	struct usb_endpoint_descriptor *bulk_out;
> > > +	struct usb_endpoint_descriptor *bulk_in;
> > > +	struct usb_endpoint_descriptor *intr_in;
> > > +	struct ch341_ddata *ddata;
> > > +	int ret;
> > > +
> > > +	ddata = devm_kzalloc(&iface->dev, sizeof(*ddata), GFP_KERNEL);
> > > +	if (!ddata)
> > > +		return -ENOMEM;
> > > +
> > > +	ddata->usb_dev = interface_to_usbdev(iface);
> > > +	mutex_init(&ddata->usb_lock);
> > > +
> > > +	ret = usb_find_common_endpoints(iface->cur_altsetting, &bulk_in,
> > > +					&bulk_out, &intr_in, NULL);
> > > +	if (ret) {
> > > +		dev_err(&iface->dev, "Could not find all endpoints\n");
> > > +		return -ENODEV;
> > > +	}
> > > +
> > > +	ddata->ep_in = bulk_in->bEndpointAddress;
> > > +	ddata->ep_out = bulk_out->bEndpointAddress;
> > > +	ddata->ep_intr = intr_in->bEndpointAddress;
> > > +	ddata->ep_intr_interval = intr_in->bInterval;
> > > +
> > > +	usb_set_intfdata(iface, ddata);
> > > +
> > > +	ret = mfd_add_devices(&iface->dev, PLATFORM_DEVID_AUTO, ch341_devs,
> > > +			      ARRAY_SIZE(ch341_devs), NULL, 0, NULL);
> > > +	if (ret)
> > > +		return dev_err_probe(&iface->dev, ret,
> > > +				     "Failed to register child devices\n");
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static void ch341_usb_disconnect(struct usb_interface *usb_if)
> > > +{
> > > +	mfd_remove_devices(&usb_if->dev);
> > > +}
> > > +
> > > +static const struct usb_device_id ch341_usb_table[] = {
> > > +	{ USB_DEVICE(0x1a86, 0x5512) },
> > > +	{ }
> > > +};
> > > +MODULE_DEVICE_TABLE(usb, ch341_usb_table);
> > > +
> > > +static struct usb_driver ch341_usb_driver = {
> > > +	.name       = "ch341-mfd",
> > > +	.id_table   = ch341_usb_table,
> > > +	.probe      = ch341_usb_probe,
> > > +	.disconnect = ch341_usb_disconnect,
> > > +};
> > > +module_usb_driver(ch341_usb_driver);
> > > +
> > > +MODULE_AUTHOR("Frank Zago <frank@zago.net>");
> > > +MODULE_DESCRIPTION("CH341 USB to I2C/SPI/GPIO adapter");
> > > +MODULE_LICENSE("GPL");
> > > diff --git a/include/linux/mfd/ch341.h b/include/linux/mfd/ch341.h
> > > new file mode 100644
> > > index 000000000000..44f5da0720bd
> > > --- /dev/null
> > > +++ b/include/linux/mfd/ch341.h
> > > @@ -0,0 +1,18 @@
> > > +/* SPDX-License-Identifier: GPL-2.0 */
> > > +/* Definitions for the CH341 driver */
> > > +
> > > +#include <linux/mutex.h>
> > > +#include <linux/types.h>
> > > +
> > > +struct usb_device;
> > > +struct usb_interface;
> > > +
> > > +struct ch341_ddata {
> > > +	struct usb_device *usb_dev;
> > > +	struct mutex usb_lock;
> > > +
> > > +	int ep_in;
> > > +	int ep_out;
> > > +	int ep_intr;
> > > +	u8 ep_intr_interval;
> > > +};
> 
> 
> Looks sane enough, but doesn't actually do any USB data transfers, maybe
> that happens somewhere else...

I expect those to happen in *both* of these:

  static const struct mfd_cell ch341_devs[] = {
	{
		.name = "ch341-gpio",
	},
	{
		.name = "ch341-i2c",
	},
  };

Is that correct Frank?

> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Thanks.

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: [PATCH v6 1/4] mfd: ch341: add core driver for the WCH CH341 in I2C/SPI/GPIO mode

[Frank Zago]

On 6/27/22 09:43, Lee Jones wrote:
> On Mon, 27 Jun 2022, Greg Kroah-Hartman wrote:
> 
>> On Mon, Jun 27, 2022 at 03:04:32PM +0100, Lee Jones wrote:
>>> USB review please.
>>>
>>>> The CH341 is a multifunction chip, presenting 3 different USB PID. One
>>>>
>>>> of these functions is for I2C/SPI/GPIO. This new set of drivers will
>>>> manage I2C and GPIO.
>>>>
>>>> Signed-off-by: frank zago <frank@zago.net>
>>>> ---
>>>>  MAINTAINERS               |  7 +++
>>>>  drivers/mfd/Kconfig       | 10 +++++
>>>>  drivers/mfd/Makefile      |  1 +
>>>>  drivers/mfd/ch341-core.c  | 90 +++++++++++++++++++++++++++++++++++++++
>>>>  include/linux/mfd/ch341.h | 18 ++++++++
>>>>  5 files changed, 126 insertions(+)
>>>>  create mode 100644 drivers/mfd/ch341-core.c
>>>>  create mode 100644 include/linux/mfd/ch341.h
>>>>
>>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>>> index 43d3d07afccd..628eeaa9bf68 100644
>>>> --- a/MAINTAINERS
>>>> +++ b/MAINTAINERS
>>>> @@ -21475,6 +21475,13 @@ M:	David Härdeman <david@hardeman.nu>
>>>>  S:	Maintained
>>>>  F:	drivers/media/rc/winbond-cir.c
>>>>  
>>>> +WINCHIPHEAD CH341 I2C/GPIO MFD DRIVER
>>>> +M:	Frank Zago <frank@zago.net>
>>>> +L:	linux-usb@vger.kernel.org
>>>> +S:	Maintained
>>>> +F:	drivers/mfd/ch341-core.c
>>>> +F:	include/linux/mfd/ch341.h
>>>> +
>>>>  WINSYSTEMS EBC-C384 WATCHDOG DRIVER
>>>>  M:	William Breathitt Gray <vilhelm.gray@gmail.com>
>>>>  L:	linux-watchdog@vger.kernel.org
>>>> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
>>>> index 3b59456f5545..893acc821a42 100644
>>>> --- a/drivers/mfd/Kconfig
>>>> +++ b/drivers/mfd/Kconfig
>>>> @@ -1784,6 +1784,16 @@ config MFD_LOCHNAGAR
>>>>  	help
>>>>  	  Support for Cirrus Logic Lochnagar audio development board.
>>>>  
>>>> +config MFD_CH341
>>>> +	tristate "WinChipHead CH341 in I2C/SPI/GPIO mode"
>>>> +	depends on USB
>>>> +	help
>>>> +	  If you say yes to this option, support for the CH341 series
>>>> +	  of chips, running in I2C/SPI/GPIO mode will be included.
>>>> +
>>>> +	  This driver can also be built as a module.  If so, the
>>>> +	  module will be called ch341-core.
>>>> +
>>>>  config MFD_ARIZONA
>>>>  	select REGMAP
>>>>  	select REGMAP_IRQ
>>>> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
>>>> index 858cacf659d6..fd615ab3929f 100644
>>>> --- a/drivers/mfd/Makefile
>>>> +++ b/drivers/mfd/Makefile
>>>> @@ -13,6 +13,7 @@ obj-$(CONFIG_MFD_ASIC3)		+= asic3.o tmio_core.o
>>>>  obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835-pm.o
>>>>  obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
>>>>  obj-$(CONFIG_MFD_BD9571MWV)	+= bd9571mwv.o
>>>> +obj-$(CONFIG_MFD_CH341)		+= ch341-core.o
>>>>  obj-$(CONFIG_MFD_CROS_EC_DEV)	+= cros_ec_dev.o
>>>>  obj-$(CONFIG_MFD_ENE_KB3930)	+= ene-kb3930.o
>>>>  obj-$(CONFIG_MFD_EXYNOS_LPASS)	+= exynos-lpass.o
>>>> diff --git a/drivers/mfd/ch341-core.c b/drivers/mfd/ch341-core.c
>>>> new file mode 100644
>>>> index 000000000000..f08a67dd6074
>>>> --- /dev/null
>>>> +++ b/drivers/mfd/ch341-core.c
>>>> @@ -0,0 +1,90 @@
>>>> +// SPDX-License-Identifier: GPL-2.0
>>>> +/*
>>>> + * Core driver for the CH341A, CH341B and CH341T in I2C/SPI/GPIO
>>>> + * mode. There are cell drivers available for I2C and GPIO. SPI is not
>>>> + * yet supported.
>>>> + *
>>>> + * Copyright 2022, Frank Zago
>>>> + * Copyright (c) 2017 Gunar Schorcht (gunar@schorcht.net)
>>>> + * Copyright (c) 2016 Tse Lun Bien
>>>> + * Copyright (c) 2014 Marco Gittler
>>>> + * Copyright (c) 2006-2007 Till Harbaum (Till@Harbaum.org)
>>>> + */
>>>> +
>>>> +#include <linux/kernel.h>
>>>> +#include <linux/mfd/ch341.h>
>>>> +#include <linux/mfd/core.h>
>>>> +#include <linux/module.h>
>>>> +#include <linux/slab.h>
>>>> +#include <linux/usb.h>
>>>> +
>>>> +static const struct mfd_cell ch341_devs[] = {
>>>> +	{
>>>> +		.name = "ch341-gpio",
>>>> +	},
>>>> +	{
>>>> +		.name = "ch341-i2c",
>>>> +	},
>>>> +};
>>>> +
>>>> +static int ch341_usb_probe(struct usb_interface *iface,
>>>> +			   const struct usb_device_id *usb_id)
>>>> +{
>>>> +	struct usb_endpoint_descriptor *bulk_out;
>>>> +	struct usb_endpoint_descriptor *bulk_in;
>>>> +	struct usb_endpoint_descriptor *intr_in;
>>>> +	struct ch341_ddata *ddata;
>>>> +	int ret;
>>>> +
>>>> +	ddata = devm_kzalloc(&iface->dev, sizeof(*ddata), GFP_KERNEL);
>>>> +	if (!ddata)
>>>> +		return -ENOMEM;
>>>> +
>>>> +	ddata->usb_dev = interface_to_usbdev(iface);
>>>> +	mutex_init(&ddata->usb_lock);
>>>> +
>>>> +	ret = usb_find_common_endpoints(iface->cur_altsetting, &bulk_in,
>>>> +					&bulk_out, &intr_in, NULL);
>>>> +	if (ret) {
>>>> +		dev_err(&iface->dev, "Could not find all endpoints\n");
>>>> +		return -ENODEV;
>>>> +	}
>>>> +
>>>> +	ddata->ep_in = bulk_in->bEndpointAddress;
>>>> +	ddata->ep_out = bulk_out->bEndpointAddress;
>>>> +	ddata->ep_intr = intr_in->bEndpointAddress;
>>>> +	ddata->ep_intr_interval = intr_in->bInterval;
>>>> +
>>>> +	usb_set_intfdata(iface, ddata);
>>>> +
>>>> +	ret = mfd_add_devices(&iface->dev, PLATFORM_DEVID_AUTO, ch341_devs,
>>>> +			      ARRAY_SIZE(ch341_devs), NULL, 0, NULL);
>>>> +	if (ret)
>>>> +		return dev_err_probe(&iface->dev, ret,
>>>> +				     "Failed to register child devices\n");
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static void ch341_usb_disconnect(struct usb_interface *usb_if)
>>>> +{
>>>> +	mfd_remove_devices(&usb_if->dev);
>>>> +}
>>>> +
>>>> +static const struct usb_device_id ch341_usb_table[] = {
>>>> +	{ USB_DEVICE(0x1a86, 0x5512) },
>>>> +	{ }
>>>> +};
>>>> +MODULE_DEVICE_TABLE(usb, ch341_usb_table);
>>>> +
>>>> +static struct usb_driver ch341_usb_driver = {
>>>> +	.name       = "ch341-mfd",
>>>> +	.id_table   = ch341_usb_table,
>>>> +	.probe      = ch341_usb_probe,
>>>> +	.disconnect = ch341_usb_disconnect,
>>>> +};
>>>> +module_usb_driver(ch341_usb_driver);
>>>> +
>>>> +MODULE_AUTHOR("Frank Zago <frank@zago.net>");
>>>> +MODULE_DESCRIPTION("CH341 USB to I2C/SPI/GPIO adapter");
>>>> +MODULE_LICENSE("GPL");
>>>> diff --git a/include/linux/mfd/ch341.h b/include/linux/mfd/ch341.h
>>>> new file mode 100644
>>>> index 000000000000..44f5da0720bd
>>>> --- /dev/null
>>>> +++ b/include/linux/mfd/ch341.h
>>>> @@ -0,0 +1,18 @@
>>>> +/* SPDX-License-Identifier: GPL-2.0 */
>>>> +/* Definitions for the CH341 driver */
>>>> +
>>>> +#include <linux/mutex.h>
>>>> +#include <linux/types.h>
>>>> +
>>>> +struct usb_device;
>>>> +struct usb_interface;
>>>> +
>>>> +struct ch341_ddata {
>>>> +	struct usb_device *usb_dev;
>>>> +	struct mutex usb_lock;
>>>> +
>>>> +	int ep_in;
>>>> +	int ep_out;
>>>> +	int ep_intr;
>>>> +	u8 ep_intr_interval;
>>>> +};
>>
>>
>> Looks sane enough, but doesn't actually do any USB data transfers, maybe
>> that happens somewhere else...
> 
> I expect those to happen in *both* of these:
> 
>   static const struct mfd_cell ch341_devs[] = {
> 	{
> 		.name = "ch341-gpio",
> 	},
> 	{
> 		.name = "ch341-i2c",
> 	},
>   };
> 
> Is that correct Frank?

Yes, that's correct.

Frank

Re: [PATCH v6 1/4] mfd: ch341: add core driver for the WCH CH341 in I2C/SPI/GPIO mode

[Lee Jones]

On Wed, 15 Jun 2022, frank zago wrote:

> The CH341 is a multifunction chip, presenting 3 different USB PID. One
> of these functions is for I2C/SPI/GPIO. This new set of drivers will
> manage I2C and GPIO.
> 
> Signed-off-by: frank zago <frank@zago.net>
> ---
>  MAINTAINERS               |  7 +++
>  drivers/mfd/Kconfig       | 10 +++++
>  drivers/mfd/Makefile      |  1 +
>  drivers/mfd/ch341-core.c  | 90 +++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/ch341.h | 18 ++++++++
>  5 files changed, 126 insertions(+)
>  create mode 100644 drivers/mfd/ch341-core.c
>  create mode 100644 include/linux/mfd/ch341.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 43d3d07afccd..628eeaa9bf68 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21475,6 +21475,13 @@ M:	David Härdeman <david@hardeman.nu>
>  S:	Maintained
>  F:	drivers/media/rc/winbond-cir.c
>  
> +WINCHIPHEAD CH341 I2C/GPIO MFD DRIVER
> +M:	Frank Zago <frank@zago.net>
> +L:	linux-usb@vger.kernel.org
> +S:	Maintained
> +F:	drivers/mfd/ch341-core.c
> +F:	include/linux/mfd/ch341.h
> +
>  WINSYSTEMS EBC-C384 WATCHDOG DRIVER
>  M:	William Breathitt Gray <vilhelm.gray@gmail.com>
>  L:	linux-watchdog@vger.kernel.org
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 3b59456f5545..893acc821a42 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -1784,6 +1784,16 @@ config MFD_LOCHNAGAR
>  	help
>  	  Support for Cirrus Logic Lochnagar audio development board.
>  
> +config MFD_CH341
> +	tristate "WinChipHead CH341 in I2C/SPI/GPIO mode"
> +	depends on USB
> +	help
> +	  If you say yes to this option, support for the CH341 series
> +	  of chips, running in I2C/SPI/GPIO mode will be included.
> +
> +	  This driver can also be built as a module.  If so, the
> +	  module will be called ch341-core.
> +
>  config MFD_ARIZONA
>  	select REGMAP
>  	select REGMAP_IRQ
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 858cacf659d6..fd615ab3929f 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -13,6 +13,7 @@ obj-$(CONFIG_MFD_ASIC3)		+= asic3.o tmio_core.o
>  obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835-pm.o
>  obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
>  obj-$(CONFIG_MFD_BD9571MWV)	+= bd9571mwv.o
> +obj-$(CONFIG_MFD_CH341)		+= ch341-core.o
>  obj-$(CONFIG_MFD_CROS_EC_DEV)	+= cros_ec_dev.o
>  obj-$(CONFIG_MFD_ENE_KB3930)	+= ene-kb3930.o
>  obj-$(CONFIG_MFD_EXYNOS_LPASS)	+= exynos-lpass.o
> diff --git a/drivers/mfd/ch341-core.c b/drivers/mfd/ch341-core.c
> new file mode 100644
> index 000000000000..f08a67dd6074
> --- /dev/null
> +++ b/drivers/mfd/ch341-core.c
> @@ -0,0 +1,90 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Core driver for the CH341A, CH341B and CH341T in I2C/SPI/GPIO
> + * mode. There are cell drivers available for I2C and GPIO. SPI is not
> + * yet supported.
> + *
> + * Copyright 2022, Frank Zago
> + * Copyright (c) 2017 Gunar Schorcht (gunar@schorcht.net)
> + * Copyright (c) 2016 Tse Lun Bien
> + * Copyright (c) 2014 Marco Gittler
> + * Copyright (c) 2006-2007 Till Harbaum (Till@Harbaum.org)
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/mfd/ch341.h>
> +#include <linux/mfd/core.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/usb.h>
> +
> +static const struct mfd_cell ch341_devs[] = {
> +	{
> +		.name = "ch341-gpio",
> +	},
> +	{
> +		.name = "ch341-i2c",
> +	},
> +};

These should both be on one line each.

> +static int ch341_usb_probe(struct usb_interface *iface,
> +			   const struct usb_device_id *usb_id)
> +{
> +	struct usb_endpoint_descriptor *bulk_out;
> +	struct usb_endpoint_descriptor *bulk_in;
> +	struct usb_endpoint_descriptor *intr_in;
> +	struct ch341_ddata *ddata;
> +	int ret;
> +
> +	ddata = devm_kzalloc(&iface->dev, sizeof(*ddata), GFP_KERNEL);
> +	if (!ddata)
> +		return -ENOMEM;
> +
> +	ddata->usb_dev = interface_to_usbdev(iface);
> +	mutex_init(&ddata->usb_lock);
> +
> +	ret = usb_find_common_endpoints(iface->cur_altsetting, &bulk_in,
> +					&bulk_out, &intr_in, NULL);
> +	if (ret) {
> +		dev_err(&iface->dev, "Could not find all endpoints\n");
> +		return -ENODEV;
> +	}
> +
> +	ddata->ep_in = bulk_in->bEndpointAddress;
> +	ddata->ep_out = bulk_out->bEndpointAddress;
> +	ddata->ep_intr = intr_in->bEndpointAddress;
> +	ddata->ep_intr_interval = intr_in->bInterval;
> +
> +	usb_set_intfdata(iface, ddata);
> +
> +	ret = mfd_add_devices(&iface->dev, PLATFORM_DEVID_AUTO, ch341_devs,
> +			      ARRAY_SIZE(ch341_devs), NULL, 0, NULL);
> +	if (ret)
> +		return dev_err_probe(&iface->dev, ret,
> +				     "Failed to register child devices\n");
> +
> +	return 0;
> +}
> +
> +static void ch341_usb_disconnect(struct usb_interface *usb_if)
> +{
> +	mfd_remove_devices(&usb_if->dev);

Why not use the devm_* version?

> +}
> +
> +static const struct usb_device_id ch341_usb_table[] = {
> +	{ USB_DEVICE(0x1a86, 0x5512) },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(usb, ch341_usb_table);
> +
> +static struct usb_driver ch341_usb_driver = {
> +	.name       = "ch341-mfd",
> +	.id_table   = ch341_usb_table,
> +	.probe      = ch341_usb_probe,
> +	.disconnect = ch341_usb_disconnect,
> +};
> +module_usb_driver(ch341_usb_driver);
> +
> +MODULE_AUTHOR("Frank Zago <frank@zago.net>");
> +MODULE_DESCRIPTION("CH341 USB to I2C/SPI/GPIO adapter");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/mfd/ch341.h b/include/linux/mfd/ch341.h
> new file mode 100644
> index 000000000000..44f5da0720bd
> --- /dev/null
> +++ b/include/linux/mfd/ch341.h
> @@ -0,0 +1,18 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Definitions for the CH341 driver */

What definitions?

> +
> +#include <linux/mutex.h>
> +#include <linux/types.h>
> +
> +struct usb_device;
> +struct usb_interface;
> +
> +struct ch341_ddata {
> +	struct usb_device *usb_dev;
> +	struct mutex usb_lock;
> +
> +	int ep_in;
> +	int ep_out;
> +	int ep_intr;
> +	u8 ep_intr_interval;
> +};

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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