The Nuvoton NCT6694 is a peripheral expander with 16 GPIO chips,
6 I2C controllers, 2 CANfd controllers, 2 Watchdog timers, ADC,
PWM, and RTC.

This driver implements USB device functionality and shares the
chip's peripherals as a child device.

Each child device can use the USB functions nct6694_read_msg()
and nct6694_write_msg() to issue a command. They can also request
interrupt that will be called when the USB device receives its
interrupt pipe.

Signed-off-by: Ming Yu <a0282524688@gmail.com>
---
 MAINTAINERS                 |   7 +
 drivers/mfd/Kconfig         |  18 ++
 drivers/mfd/Makefile        |   2 +
 drivers/mfd/nct6694.c       | 378 ++++++++++++++++++++++++++++++++++++
 include/linux/mfd/nct6694.h | 102 ++++++++++
 5 files changed, 507 insertions(+)
 create mode 100644 drivers/mfd/nct6694.c
 create mode 100644 include/linux/mfd/nct6694.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 873aa2cce4d7..c700a0b96960 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16918,6 +16918,13 @@ F:	drivers/nubus/
 F:	include/linux/nubus.h
 F:	include/uapi/linux/nubus.h
 
+NUVOTON NCT6694 MFD DRIVER
+M:	Ming Yu <tmyu0@nuvoton.com>
+L:	linux-kernel@vger.kernel.org
+S:	Supported
+F:	drivers/mfd/nct6694.c
+F:	include/linux/mfd/nct6694.h
+
 NVIDIA (rivafb and nvidiafb) FRAMEBUFFER DRIVER
 M:	Antonino Daplas <adaplas@gmail.com>
 L:	linux-fbdev@vger.kernel.org
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 6b0682af6e32..c97a2bdcea0b 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1045,6 +1045,24 @@ config MFD_MENF21BMC
 	  This driver can also be built as a module. If so the module
 	  will be called menf21bmc.
 
+config MFD_NCT6694
+	tristate "Nuvoton NCT6694 support"
+	select MFD_CORE
+	depends on USB
+	help
+	  This enables support for the Nuvoton USB device NCT6694, which shares
+	  peripherals.
+
+	  This driver provides core APIs to access the NCT6694 hardware
+	  monitoring and control features.
+
+	  The NCT6694 is a versatile multi-function device that supports
+	  functionalities such as GPIO, I2C, CAN, WDT, HWMON, and RTC
+	  management.
+
+	  Additional drivers must be enabled to utilize the specific
+	  functionalities of the device.
+
 config MFD_OCELOT
 	tristate "Microsemi Ocelot External Control Support"
 	depends on SPI_MASTER
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 9220eaf7cf12..7725b732e265 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -121,6 +121,8 @@ obj-$(CONFIG_MFD_MC13XXX)	+= mc13xxx-core.o
 obj-$(CONFIG_MFD_MC13XXX_SPI)	+= mc13xxx-spi.o
 obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
 
+obj-$(CONFIG_MFD_NCT6694)	+= nct6694.o
+
 obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
 
 ocelot-soc-objs			:= ocelot-core.o ocelot-spi.o
diff --git a/drivers/mfd/nct6694.c b/drivers/mfd/nct6694.c
new file mode 100644
index 000000000000..c82457679ca6
--- /dev/null
+++ b/drivers/mfd/nct6694.c
@@ -0,0 +1,378 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Nuvoton NCT6694 core driver using USB interface to provide
+ * access to the NCT6694 hardware monitoring and control features.
+ *
+ * The NCT6694 is a versatile multi-function device that supports
+ * functionalities such as GPIO, I2C, CAN, WDT, HWMON and RTC
+ * management.
+ *
+ * Copyright (C) 2024 Nuvoton Technology Corp.
+ */
+
+#include <linux/bits.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/nct6694.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+static const struct mfd_cell nct6694_dev[] = {
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x0),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x1),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x2),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x3),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x4),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x5),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x6),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x7),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x8),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x9),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xA),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xB),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xC),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xD),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xE),
+	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xF),
+
+	MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x0),
+	MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x1),
+	MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x2),
+	MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x3),
+	MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x4),
+	MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x5),
+
+	MFD_CELL_BASIC("nct6694_canfd", NULL, NULL, 0, 0x0),
+	MFD_CELL_BASIC("nct6694_canfd", NULL, NULL, 0, 0x1),
+
+	MFD_CELL_BASIC("nct6694_wdt", NULL, NULL, 0, 0x0),
+	MFD_CELL_BASIC("nct6694_wdt", NULL, NULL, 0, 0x1),
+
+	MFD_CELL_NAME("nct6694-hwmon"),
+	MFD_CELL_NAME("rtc-nct6694"),
+};
+
+static int nct6694_response_err_handling(struct nct6694 *nct6694,
+					 unsigned char err_status)
+{
+	switch (err_status) {
+	case NCT6694_NO_ERROR:
+		return err_status;
+	case NCT6694_NOT_SUPPORT_ERROR:
+		dev_warn(nct6694->dev, "Command is not supported!\n");
+		break;
+	case NCT6694_NO_RESPONSE_ERROR:
+		dev_warn(nct6694->dev, "Command received no response!\n");
+		break;
+	case NCT6694_TIMEOUT_ERROR:
+		dev_warn(nct6694->dev, "Command timed out!\n");
+		break;
+	case NCT6694_PENDING:
+		dev_warn(nct6694->dev, "Command is pending!\n");
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return -EIO;
+}
+
+int nct6694_read_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf)
+{
+	union nct6694_usb_msg *msg = nct6694->usb_msg;
+	int tx_len, rx_len, ret;
+
+	guard(mutex)(&nct6694->access_lock);
+
+	/* Send command packet to USB device */
+	memcpy(&msg->cmd_header, cmd_hd, sizeof(*cmd_hd));
+	msg->cmd_header.hctrl = NCT6694_HCTRL_GET;
+
+	ret = usb_bulk_msg(nct6694->udev,
+			   usb_sndbulkpipe(nct6694->udev, NCT6694_BULK_OUT_EP),
+			   &msg->cmd_header, sizeof(*msg), &tx_len,
+			   nct6694->timeout);
+	if (ret)
+		return ret;
+
+	/* Receive response packet from USB device */
+	ret = usb_bulk_msg(nct6694->udev,
+			   usb_rcvbulkpipe(nct6694->udev, NCT6694_BULK_IN_EP),
+			   &msg->response_header, sizeof(*msg), &rx_len,
+			   nct6694->timeout);
+	if (ret)
+		return ret;
+
+	/* Receive data packet from USB device */
+	ret = usb_bulk_msg(nct6694->udev,
+			   usb_rcvbulkpipe(nct6694->udev, NCT6694_BULK_IN_EP),
+			   buf, le16_to_cpu(cmd_hd->len), &rx_len,
+			   nct6694->timeout);
+	if (ret)
+		return ret;
+
+	if (rx_len != le16_to_cpu(cmd_hd->len)) {
+		dev_err(nct6694->dev, "Expected received length %d, but got %d\n",
+			le16_to_cpu(cmd_hd->len), rx_len);
+		return -EIO;
+	}
+
+	return nct6694_response_err_handling(nct6694, msg->response_header.sts);
+}
+EXPORT_SYMBOL(nct6694_read_msg);
+
+int nct6694_write_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf)
+{
+	union nct6694_usb_msg *msg = nct6694->usb_msg;
+	int tx_len, rx_len, ret;
+
+	guard(mutex)(&nct6694->access_lock);
+
+	/* Send command packet to USB device */
+	memcpy(&msg->cmd_header, cmd_hd, sizeof(*cmd_hd));
+	msg->cmd_header.hctrl = NCT6694_HCTRL_SET;
+
+	ret = usb_bulk_msg(nct6694->udev,
+			   usb_sndbulkpipe(nct6694->udev, NCT6694_BULK_OUT_EP),
+			   &msg->cmd_header, sizeof(*msg), &tx_len,
+			   nct6694->timeout);
+	if (ret)
+		return ret;
+
+	/* Send data packet to USB device */
+	ret = usb_bulk_msg(nct6694->udev,
+			   usb_sndbulkpipe(nct6694->udev, NCT6694_BULK_OUT_EP),
+			   buf, le16_to_cpu(cmd_hd->len), &tx_len,
+			   nct6694->timeout);
+	if (ret)
+		return ret;
+
+	/* Receive response packet from USB device */
+	ret = usb_bulk_msg(nct6694->udev,
+			   usb_rcvbulkpipe(nct6694->udev, NCT6694_BULK_IN_EP),
+			   &msg->response_header, sizeof(*msg), &rx_len,
+			   nct6694->timeout);
+	if (ret)
+		return ret;
+
+	/* Receive data packet from USB device */
+	ret = usb_bulk_msg(nct6694->udev,
+			   usb_rcvbulkpipe(nct6694->udev, NCT6694_BULK_IN_EP),
+			   buf, le16_to_cpu(cmd_hd->len), &rx_len,
+			   nct6694->timeout);
+	if (ret)
+		return ret;
+
+	if (rx_len != le16_to_cpu(cmd_hd->len)) {
+		dev_err(nct6694->dev, "Expected transmitted length %d, but got %d\n",
+			le16_to_cpu(cmd_hd->len), rx_len);
+		return -EIO;
+	}
+
+	return nct6694_response_err_handling(nct6694, msg->response_header.sts);
+}
+EXPORT_SYMBOL(nct6694_write_msg);
+
+static void usb_int_callback(struct urb *urb)
+{
+	struct nct6694 *nct6694 = urb->context;
+	unsigned int *int_status = urb->transfer_buffer;
+	int ret;
+
+	switch (urb->status) {
+	case 0:
+		break;
+	case -ECONNRESET:
+	case -ENOENT:
+	case -ESHUTDOWN:
+		return;
+	default:
+		goto resubmit;
+	}
+
+	while (*int_status) {
+		int irq = __ffs(*int_status);
+
+		generic_handle_irq_safe(irq_find_mapping(nct6694->domain, irq));
+		*int_status &= ~BIT(irq);
+	}
+
+resubmit:
+	ret = usb_submit_urb(urb, GFP_ATOMIC);
+	if (ret)
+		dev_dbg(nct6694->dev, "%s: Failed to resubmit urb, status %pe",
+			__func__, ERR_PTR(ret));
+}
+
+static void nct6694_irq_lock(struct irq_data *data)
+{
+	struct nct6694 *nct6694 = irq_data_get_irq_chip_data(data);
+
+	mutex_lock(&nct6694->irq_lock);
+}
+
+static void nct6694_irq_sync_unlock(struct irq_data *data)
+{
+	struct nct6694 *nct6694 = irq_data_get_irq_chip_data(data);
+
+	mutex_unlock(&nct6694->irq_lock);
+}
+
+static void nct6694_irq_enable(struct irq_data *data)
+{
+	struct nct6694 *nct6694 = irq_data_get_irq_chip_data(data);
+	irq_hw_number_t hwirq = irqd_to_hwirq(data);
+
+	nct6694->irq_enable |= BIT(hwirq);
+}
+
+static void nct6694_irq_disable(struct irq_data *data)
+{
+	struct nct6694 *nct6694 = irq_data_get_irq_chip_data(data);
+	irq_hw_number_t hwirq = irqd_to_hwirq(data);
+
+	nct6694->irq_enable &= ~BIT(hwirq);
+}
+
+static const struct irq_chip nct6694_irq_chip = {
+	.name = "nct6694-irq",
+	.flags = IRQCHIP_SKIP_SET_WAKE,
+	.irq_bus_lock = nct6694_irq_lock,
+	.irq_bus_sync_unlock = nct6694_irq_sync_unlock,
+	.irq_enable = nct6694_irq_enable,
+	.irq_disable = nct6694_irq_disable,
+};
+
+static int nct6694_irq_domain_map(struct irq_domain *d, unsigned int irq,
+				  irq_hw_number_t hw)
+{
+	struct nct6694 *nct6694 = d->host_data;
+
+	irq_set_chip_data(irq, nct6694);
+	irq_set_chip_and_handler(irq, &nct6694_irq_chip, handle_simple_irq);
+
+	return 0;
+}
+
+static void nct6694_irq_domain_unmap(struct irq_domain *d, unsigned int irq)
+{
+	irq_set_chip_and_handler(irq, NULL, NULL);
+	irq_set_chip_data(irq, NULL);
+}
+
+static const struct irq_domain_ops nct6694_irq_domain_ops = {
+	.map	= nct6694_irq_domain_map,
+	.unmap	= nct6694_irq_domain_unmap,
+};
+
+static int nct6694_usb_probe(struct usb_interface *iface,
+			     const struct usb_device_id *id)
+{
+	struct usb_device *udev = interface_to_usbdev(iface);
+	struct usb_endpoint_descriptor *int_endpoint;
+	struct usb_host_interface *interface;
+	struct device *dev = &iface->dev;
+	struct nct6694 *nct6694;
+	int pipe, maxp;
+	int ret;
+
+	nct6694 = devm_kzalloc(dev, sizeof(*nct6694), GFP_KERNEL);
+	if (!nct6694)
+		return -ENOMEM;
+
+	pipe = usb_rcvintpipe(udev, NCT6694_INT_IN_EP);
+	maxp = usb_maxpacket(udev, pipe);
+
+	nct6694->usb_msg = devm_kzalloc(dev, sizeof(union nct6694_usb_msg), GFP_KERNEL);
+	if (!nct6694->usb_msg)
+		return -ENOMEM;
+
+	nct6694->int_buffer = devm_kzalloc(dev, maxp, GFP_KERNEL);
+	if (!nct6694->int_buffer)
+		return -ENOMEM;
+
+	nct6694->int_in_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!nct6694->int_in_urb)
+		return -ENOMEM;
+
+	nct6694->domain = irq_domain_add_simple(NULL, NCT6694_NR_IRQS, 0,
+						&nct6694_irq_domain_ops,
+						nct6694);
+	if (!nct6694->domain) {
+		ret = -ENODEV;
+		goto err_urb;
+	}
+
+	nct6694->dev = dev;
+	nct6694->udev = udev;
+	nct6694->timeout = NCT6694_URB_TIMEOUT;	/* Wait until URB completes */
+
+	ret = devm_mutex_init(dev, &nct6694->access_lock);
+	if (ret)
+		goto err_urb;
+
+	ret = devm_mutex_init(dev, &nct6694->irq_lock);
+	if (ret)
+		goto err_urb;
+
+	interface = iface->cur_altsetting;
+	int_endpoint = &interface->endpoint[0].desc;
+	if (!usb_endpoint_is_int_in(int_endpoint)) {
+		ret = -ENODEV;
+		goto err_urb;
+	}
+	usb_fill_int_urb(nct6694->int_in_urb, udev, pipe,
+			 nct6694->int_buffer, maxp, usb_int_callback,
+			 nct6694, int_endpoint->bInterval);
+	ret = usb_submit_urb(nct6694->int_in_urb, GFP_KERNEL);
+	if (ret)
+		goto err_urb;
+
+	usb_set_intfdata(iface, nct6694);
+
+	ret = mfd_add_hotplug_devices(dev, nct6694_dev, ARRAY_SIZE(nct6694_dev));
+	if (ret)
+		goto err_mfd;
+
+	return 0;
+
+err_mfd:
+	usb_kill_urb(nct6694->int_in_urb);
+err_urb:
+	usb_free_urb(nct6694->int_in_urb);
+	return ret;
+}
+
+static void nct6694_usb_disconnect(struct usb_interface *iface)
+{
+	struct nct6694 *nct6694 = usb_get_intfdata(iface);
+
+	mfd_remove_devices(nct6694->dev);
+	usb_kill_urb(nct6694->int_in_urb);
+	usb_free_urb(nct6694->int_in_urb);
+}
+
+static const struct usb_device_id nct6694_ids[] = {
+	{ USB_DEVICE_AND_INTERFACE_INFO(NCT6694_VENDOR_ID,
+					NCT6694_PRODUCT_ID,
+					0xFF, 0x00, 0x00)},
+	{}
+};
+MODULE_DEVICE_TABLE(usb, nct6694_ids);
+
+static struct usb_driver nct6694_usb_driver = {
+	.name	= "nct6694",
+	.id_table = nct6694_ids,
+	.probe = nct6694_usb_probe,
+	.disconnect = nct6694_usb_disconnect,
+};
+
+module_usb_driver(nct6694_usb_driver);
+
+MODULE_DESCRIPTION("USB core driver for NCT6694");
+MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/mfd/nct6694.h b/include/linux/mfd/nct6694.h
new file mode 100644
index 000000000000..8171f975761e
--- /dev/null
+++ b/include/linux/mfd/nct6694.h
@@ -0,0 +1,102 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Nuvoton NCT6694 USB transaction and data structure.
+ *
+ * Copyright (C) 2024 Nuvoton Technology Corp.
+ */
+
+#ifndef __MFD_NCT6694_H
+#define __MFD_NCT6694_H
+
+#define NCT6694_VENDOR_ID	0x0416
+#define NCT6694_PRODUCT_ID	0x200B
+#define NCT6694_INT_IN_EP	0x81
+#define NCT6694_BULK_IN_EP	0x02
+#define NCT6694_BULK_OUT_EP	0x03
+
+#define NCT6694_HCTRL_SET	0x40
+#define NCT6694_HCTRL_GET	0x80
+
+#define NCT6694_URB_TIMEOUT	1000
+
+enum nct6694_irq_id {
+	NCT6694_IRQ_GPIO0 = 0,
+	NCT6694_IRQ_GPIO1,
+	NCT6694_IRQ_GPIO2,
+	NCT6694_IRQ_GPIO3,
+	NCT6694_IRQ_GPIO4,
+	NCT6694_IRQ_GPIO5,
+	NCT6694_IRQ_GPIO6,
+	NCT6694_IRQ_GPIO7,
+	NCT6694_IRQ_GPIO8,
+	NCT6694_IRQ_GPIO9,
+	NCT6694_IRQ_GPIOA,
+	NCT6694_IRQ_GPIOB,
+	NCT6694_IRQ_GPIOC,
+	NCT6694_IRQ_GPIOD,
+	NCT6694_IRQ_GPIOE,
+	NCT6694_IRQ_GPIOF,
+	NCT6694_IRQ_CAN0,
+	NCT6694_IRQ_CAN1,
+	NCT6694_IRQ_RTC,
+	NCT6694_NR_IRQS,
+};
+
+enum nct6694_response_err_status {
+	NCT6694_NO_ERROR = 0,
+	NCT6694_FORMAT_ERROR,
+	NCT6694_RESERVED1,
+	NCT6694_RESERVED2,
+	NCT6694_NOT_SUPPORT_ERROR,
+	NCT6694_NO_RESPONSE_ERROR,
+	NCT6694_TIMEOUT_ERROR,
+	NCT6694_PENDING,
+};
+
+struct __packed nct6694_cmd_header {
+	u8 rsv1;
+	u8 mod;
+	union __packed {
+		__le16 offset;
+		struct __packed {
+			u8 cmd;
+			u8 sel;
+		};
+	};
+	u8 hctrl;
+	u8 rsv2;
+	__le16 len;
+};
+
+struct __packed nct6694_response_header {
+	u8 sequence_id;
+	u8 sts;
+	u8 reserved[4];
+	__le16 len;
+};
+
+union __packed nct6694_usb_msg {
+	struct nct6694_cmd_header cmd_header;
+	struct nct6694_response_header response_header;
+};
+
+struct nct6694 {
+	struct device *dev;
+	struct irq_domain *domain;
+	/* Mutex to protect access to the device */
+	struct mutex access_lock;
+	/* Mutex to protect access to the IRQ */
+	struct mutex irq_lock;
+	struct urb *int_in_urb;
+	struct usb_device *udev;
+	union nct6694_usb_msg *usb_msg;
+	unsigned char *int_buffer;
+	unsigned int irq_enable;
+	/* Time in msec to wait for the URB to the complete */
+	long timeout;
+};
+
+int nct6694_read_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf);
+int nct6694_write_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf);
+
+#endif
-- 
2.34.1

On Tue, 25 Feb 2025, Ming Yu wrote:

> The Nuvoton NCT6694 is a peripheral expander with 16 GPIO chips,
> 6 I2C controllers, 2 CANfd controllers, 2 Watchdog timers, ADC,
> PWM, and RTC.

This needs to go into the Kconfig help passage.

> This driver implements USB device functionality and shares the
> chip's peripherals as a child device.

This driver doesn't implement USB functionality.

> Each child device can use the USB functions nct6694_read_msg()
> and nct6694_write_msg() to issue a command. They can also request
> interrupt that will be called when the USB device receives its
> interrupt pipe.
> 
> Signed-off-by: Ming Yu <a0282524688@gmail.com>

Why aren't you signing off with your work address?

> ---
>  MAINTAINERS                 |   7 +
>  drivers/mfd/Kconfig         |  18 ++
>  drivers/mfd/Makefile        |   2 +
>  drivers/mfd/nct6694.c       | 378 ++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/nct6694.h | 102 ++++++++++
>  5 files changed, 507 insertions(+)
>  create mode 100644 drivers/mfd/nct6694.c
>  create mode 100644 include/linux/mfd/nct6694.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 873aa2cce4d7..c700a0b96960 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -16918,6 +16918,13 @@ F:	drivers/nubus/
>  F:	include/linux/nubus.h
>  F:	include/uapi/linux/nubus.h
>  
> +NUVOTON NCT6694 MFD DRIVER
> +M:	Ming Yu <tmyu0@nuvoton.com>
> +L:	linux-kernel@vger.kernel.org

This is the default list.  You shouldn't need to add that here.

> +S:	Supported
> +F:	drivers/mfd/nct6694.c
> +F:	include/linux/mfd/nct6694.h
> +
>  NVIDIA (rivafb and nvidiafb) FRAMEBUFFER DRIVER
>  M:	Antonino Daplas <adaplas@gmail.com>
>  L:	linux-fbdev@vger.kernel.org
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 6b0682af6e32..c97a2bdcea0b 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -1045,6 +1045,24 @@ config MFD_MENF21BMC
>  	  This driver can also be built as a module. If so the module
>  	  will be called menf21bmc.
>  
> +config MFD_NCT6694
> +	tristate "Nuvoton NCT6694 support"
> +	select MFD_CORE
> +	depends on USB
> +	help
> +	  This enables support for the Nuvoton USB device NCT6694, which shares
> +	  peripherals.
> +
> +	  This driver provides core APIs to access the NCT6694 hardware
> +	  monitoring and control features.
> +
> +	  The NCT6694 is a versatile multi-function device that supports

Please drop the term multi-function device and replace it what a proper
description of the devices.

> +	  functionalities such as GPIO, I2C, CAN, WDT, HWMON, and RTC
> +	  management.

All of these line breaks should be removed.

> +	  Additional drivers must be enabled to utilize the specific
> +	  functionalities of the device.
> +
>  config MFD_OCELOT
>  	tristate "Microsemi Ocelot External Control Support"
>  	depends on SPI_MASTER
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 9220eaf7cf12..7725b732e265 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -121,6 +121,8 @@ obj-$(CONFIG_MFD_MC13XXX)	+= mc13xxx-core.o
>  obj-$(CONFIG_MFD_MC13XXX_SPI)	+= mc13xxx-spi.o
>  obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
>  
> +obj-$(CONFIG_MFD_NCT6694)	+= nct6694.o
> +
>  obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
>  
>  ocelot-soc-objs			:= ocelot-core.o ocelot-spi.o
> diff --git a/drivers/mfd/nct6694.c b/drivers/mfd/nct6694.c
> new file mode 100644
> index 000000000000..c82457679ca6
> --- /dev/null
> +++ b/drivers/mfd/nct6694.c
> @@ -0,0 +1,378 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Nuvoton NCT6694 core driver using USB interface to provide
> + * access to the NCT6694 hardware monitoring and control features.
> + *
> + * The NCT6694 is a versatile multi-function device that supports

Here too.

> + * functionalities such as GPIO, I2C, CAN, WDT, HWMON and RTC
> + * management.
> + *
> + * Copyright (C) 2024 Nuvoton Technology Corp.

This goes at the top.

> + */
> +
> +#include <linux/bits.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/irqdomain.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/nct6694.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/usb.h>
> +
> +static const struct mfd_cell nct6694_dev[] = {
> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x0),

"-gpio" usually goes on the end.

> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x1),

IDs are usually given in base-10.

Why are you manually adding the device IDs?

PLATFORM_DEVID_AUTO doesn't work for you?

> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x2),
> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x3),
> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x4),
> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x5),
> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x6),
> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x7),
> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x8),
> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x9),
> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xA),
> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xB),
> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xC),
> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xD),
> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xE),
> +	MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xF),
> +
> +	MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x0),
> +	MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x1),
> +	MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x2),
> +	MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x3),
> +	MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x4),
> +	MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x5),
> +
> +	MFD_CELL_BASIC("nct6694_canfd", NULL, NULL, 0, 0x0),

Why has the naming convention changed here?

> +	MFD_CELL_BASIC("nct6694_canfd", NULL, NULL, 0, 0x1),
> +
> +	MFD_CELL_BASIC("nct6694_wdt", NULL, NULL, 0, 0x0),
> +	MFD_CELL_BASIC("nct6694_wdt", NULL, NULL, 0, 0x1),
> +
> +	MFD_CELL_NAME("nct6694-hwmon"),
> +	MFD_CELL_NAME("rtc-nct6694"),

There doesn't seem to be any consistency here.

> +};
> +
> +static int nct6694_response_err_handling(struct nct6694 *nct6694,

> +{
> +	switch (err_status) {
> +	case NCT6694_NO_ERROR:
> +		return err_status;

This is odd since you already know this will be 0.

> +	case NCT6694_NOT_SUPPORT_ERROR:
> +		dev_warn(nct6694->dev, "Command is not supported!\n");

Why not dev_err()?

> +		break;
> +	case NCT6694_NO_RESPONSE_ERROR:
> +		dev_warn(nct6694->dev, "Command received no response!\n");
> +		break;
> +	case NCT6694_TIMEOUT_ERROR:
> +		dev_warn(nct6694->dev, "Command timed out!\n");
> +		break;
> +	case NCT6694_PENDING:
> +		dev_warn(nct6694->dev, "Command is pending!\n");

Is this an error?

> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return -EIO;
> +}
> +
> +int nct6694_read_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf)
> +{
> +	union nct6694_usb_msg *msg = nct6694->usb_msg;
> +	int tx_len, rx_len, ret;
> +
> +	guard(mutex)(&nct6694->access_lock);
> +
> +	/* Send command packet to USB device */

This doesn't really describe the next 2 lines.

Move it down?

> +	memcpy(&msg->cmd_header, cmd_hd, sizeof(*cmd_hd));
> +	msg->cmd_header.hctrl = NCT6694_HCTRL_GET;
> +
> +	ret = usb_bulk_msg(nct6694->udev,

Since you use nct6694->udev a bunch - sometimes twice in the same call,
it might be nicer to pull it into it's own variable instead of
dereferencing it all the time.

> +			   usb_sndbulkpipe(nct6694->udev, NCT6694_BULK_OUT_EP),
> +			   &msg->cmd_header, sizeof(*msg), &tx_len,
> +			   nct6694->timeout);
> +	if (ret)
> +		return ret;
> +
> +	/* Receive response packet from USB device */
> +	ret = usb_bulk_msg(nct6694->udev,
> +			   usb_rcvbulkpipe(nct6694->udev, NCT6694_BULK_IN_EP),
> +			   &msg->response_header, sizeof(*msg), &rx_len,

How can you read sizeof(*msg) Bytes (22?) into the smaller
response_header (16?) attribute?

> +			   nct6694->timeout);
> +	if (ret)
> +		return ret;
> +
> +	/* Receive data packet from USB device */
> +	ret = usb_bulk_msg(nct6694->udev,
> +			   usb_rcvbulkpipe(nct6694->udev, NCT6694_BULK_IN_EP),
> +			   buf, le16_to_cpu(cmd_hd->len), &rx_len,
> +			   nct6694->timeout);
> +	if (ret)
> +		return ret;
> +
> +	if (rx_len != le16_to_cpu(cmd_hd->len)) {
> +		dev_err(nct6694->dev, "Expected received length %d, but got %d\n",
> +			le16_to_cpu(cmd_hd->len), rx_len);
> +		return -EIO;
> +	}
> +
> +	return nct6694_response_err_handling(nct6694, msg->response_header.sts);
> +}
> +EXPORT_SYMBOL(nct6694_read_msg);
> +
> +int nct6694_write_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf)
> +{
> +	union nct6694_usb_msg *msg = nct6694->usb_msg;
> +	int tx_len, rx_len, ret;
> +
> +	guard(mutex)(&nct6694->access_lock);
> +
> +	/* Send command packet to USB device */
> +	memcpy(&msg->cmd_header, cmd_hd, sizeof(*cmd_hd));
> +	msg->cmd_header.hctrl = NCT6694_HCTRL_SET;
> +
> +	ret = usb_bulk_msg(nct6694->udev,
> +			   usb_sndbulkpipe(nct6694->udev, NCT6694_BULK_OUT_EP),
> +			   &msg->cmd_header, sizeof(*msg), &tx_len,
> +			   nct6694->timeout);
> +	if (ret)
> +		return ret;
> +
> +	/* Send data packet to USB device */
> +	ret = usb_bulk_msg(nct6694->udev,
> +			   usb_sndbulkpipe(nct6694->udev, NCT6694_BULK_OUT_EP),
> +			   buf, le16_to_cpu(cmd_hd->len), &tx_len,
> +			   nct6694->timeout);
> +	if (ret)
> +		return ret;
> +
> +	/* Receive response packet from USB device */
> +	ret = usb_bulk_msg(nct6694->udev,
> +			   usb_rcvbulkpipe(nct6694->udev, NCT6694_BULK_IN_EP),
> +			   &msg->response_header, sizeof(*msg), &rx_len,
> +			   nct6694->timeout);
> +	if (ret)
> +		return ret;
> +
> +	/* Receive data packet from USB device */
> +	ret = usb_bulk_msg(nct6694->udev,
> +			   usb_rcvbulkpipe(nct6694->udev, NCT6694_BULK_IN_EP),
> +			   buf, le16_to_cpu(cmd_hd->len), &rx_len,
> +			   nct6694->timeout);
> +	if (ret)
> +		return ret;
> +
> +	if (rx_len != le16_to_cpu(cmd_hd->len)) {
> +		dev_err(nct6694->dev, "Expected transmitted length %d, but got %d\n",
> +			le16_to_cpu(cmd_hd->len), rx_len);
> +		return -EIO;
> +	}
> +
> +	return nct6694_response_err_handling(nct6694, msg->response_header.sts);
> +}
> +EXPORT_SYMBOL(nct6694_write_msg);
> +
> +static void usb_int_callback(struct urb *urb)
> +{
> +	struct nct6694 *nct6694 = urb->context;
> +	unsigned int *int_status = urb->transfer_buffer;
> +	int ret;
> +
> +	switch (urb->status) {
> +	case 0:
> +		break;
> +	case -ECONNRESET:
> +	case -ENOENT:
> +	case -ESHUTDOWN:
> +		return;
> +	default:
> +		generic_handle_irq_safe(irq_find_mapping(nct6694->domain, irq));
> +		*int_status &= ~BIT(irq);
> +	}
> +
> +resubmit:
> +	ret = usb_submit_urb(urb, GFP_ATOMIC);
> +	if (ret)
> +		dev_dbg(nct6694->dev, "%s: Failed to resubmit urb, status %pe",

Why debug?

> +			__func__, ERR_PTR(ret));

Remove the __func__ part.

> +}
> +
> +static void nct6694_irq_lock(struct irq_data *data)
> +{
> +	struct nct6694 *nct6694 = irq_data_get_irq_chip_data(data);
> +
> +	mutex_lock(&nct6694->irq_lock);
> +}
> +
> +static void nct6694_irq_sync_unlock(struct irq_data *data)
> +{
> +	struct nct6694 *nct6694 = irq_data_get_irq_chip_data(data);
> +
> +	mutex_unlock(&nct6694->irq_lock);
> +}
> +
> +static void nct6694_irq_enable(struct irq_data *data)
> +{
> +	struct nct6694 *nct6694 = irq_data_get_irq_chip_data(data);
> +	irq_hw_number_t hwirq = irqd_to_hwirq(data);
> +
> +	nct6694->irq_enable |= BIT(hwirq);
> +}
> +
> +static void nct6694_irq_disable(struct irq_data *data)
> +{
> +	struct nct6694 *nct6694 = irq_data_get_irq_chip_data(data);
> +	irq_hw_number_t hwirq = irqd_to_hwirq(data);
> +
> +	nct6694->irq_enable &= ~BIT(hwirq);
> +}
> +
> +static const struct irq_chip nct6694_irq_chip = {
> +	.name = "nct6694-irq",
> +	.flags = IRQCHIP_SKIP_SET_WAKE,
> +	.irq_bus_lock = nct6694_irq_lock,
> +	.irq_bus_sync_unlock = nct6694_irq_sync_unlock,
> +	.irq_enable = nct6694_irq_enable,
> +	.irq_disable = nct6694_irq_disable,
> +};
> +
> +static int nct6694_irq_domain_map(struct irq_domain *d, unsigned int irq,
> +				  irq_hw_number_t hw)
> +{
> +	struct nct6694 *nct6694 = d->host_data;
> +
> +	irq_set_chip_data(irq, nct6694);
> +	irq_set_chip_and_handler(irq, &nct6694_irq_chip, handle_simple_irq);
> +
> +	return 0;
> +}
> +
> +static void nct6694_irq_domain_unmap(struct irq_domain *d, unsigned int irq)
> +{
> +	irq_set_chip_and_handler(irq, NULL, NULL);
> +	irq_set_chip_data(irq, NULL);
> +}
> +
> +static const struct irq_domain_ops nct6694_irq_domain_ops = {
> +	.map	= nct6694_irq_domain_map,
> +	.unmap	= nct6694_irq_domain_unmap,
> +};
> +
> +static int nct6694_usb_probe(struct usb_interface *iface,
> +			     const struct usb_device_id *id)
> +{
> +	struct usb_device *udev = interface_to_usbdev(iface);
> +	struct usb_endpoint_descriptor *int_endpoint;
> +	struct usb_host_interface *interface;
> +	struct device *dev = &iface->dev;
> +	struct nct6694 *nct6694;
> +	int pipe, maxp;
> +	int ret;
> +
> +	nct6694 = devm_kzalloc(dev, sizeof(*nct6694), GFP_KERNEL);
> +	if (!nct6694)
> +		return -ENOMEM;
> +
> +	pipe = usb_rcvintpipe(udev, NCT6694_INT_IN_EP);
> +	maxp = usb_maxpacket(udev, pipe);
> +
> +	nct6694->usb_msg = devm_kzalloc(dev, sizeof(union nct6694_usb_msg), GFP_KERNEL);
> +	if (!nct6694->usb_msg)
> +		return -ENOMEM;
> +
> +	nct6694->int_buffer = devm_kzalloc(dev, maxp, GFP_KERNEL);
> +	if (!nct6694->int_buffer)
> +		return -ENOMEM;
> +
> +	nct6694->int_in_urb = usb_alloc_urb(0, GFP_KERNEL);
> +	if (!nct6694->int_in_urb)
> +		return -ENOMEM;
> +
> +	nct6694->domain = irq_domain_add_simple(NULL, NCT6694_NR_IRQS, 0,
> +						&nct6694_irq_domain_ops,
> +						nct6694);
> +	if (!nct6694->domain) {
> +		ret = -ENODEV;
> +		goto err_urb;
> +	}
> +
> +	nct6694->dev = dev;
> +	nct6694->udev = udev;
> +	nct6694->timeout = NCT6694_URB_TIMEOUT;	/* Wait until URB completes */

No need to save this known value.

> +	ret = devm_mutex_init(dev, &nct6694->access_lock);
> +	if (ret)
> +		goto err_urb;
> +
> +	ret = devm_mutex_init(dev, &nct6694->irq_lock);
> +	if (ret)
> +		goto err_urb;
> +
> +	interface = iface->cur_altsetting;
> +	int_endpoint = &interface->endpoint[0].desc;
> +	if (!usb_endpoint_is_int_in(int_endpoint)) {
> +		ret = -ENODEV;
> +		goto err_urb;
> +	}
> +	usb_fill_int_urb(nct6694->int_in_urb, udev, pipe,
> +			 nct6694->int_buffer, maxp, usb_int_callback,
> +			 nct6694, int_endpoint->bInterval);
> +	ret = usb_submit_urb(nct6694->int_in_urb, GFP_KERNEL);
> +	if (ret)
> +		goto err_urb;

Please unsquash these calls - space them out.

> +
> +	usb_set_intfdata(iface, nct6694);
> +
> +	ret = mfd_add_hotplug_devices(dev, nct6694_dev, ARRAY_SIZE(nct6694_dev));
> +	if (ret)
> +		goto err_mfd;
> +
> +	return 0;
> +
> +err_mfd:
> +	usb_kill_urb(nct6694->int_in_urb);
> +err_urb:
> +	usb_free_urb(nct6694->int_in_urb);
> +	return ret;
> +}
> +
> +static void nct6694_usb_disconnect(struct usb_interface *iface)
> +{
> +	struct nct6694 *nct6694 = usb_get_intfdata(iface);
> +
> +	mfd_remove_devices(nct6694->dev);
> +	usb_kill_urb(nct6694->int_in_urb);
> +	usb_free_urb(nct6694->int_in_urb);
> +}
> +
> +static const struct usb_device_id nct6694_ids[] = {
> +	{ USB_DEVICE_AND_INTERFACE_INFO(NCT6694_VENDOR_ID,
> +					NCT6694_PRODUCT_ID,
> +					0xFF, 0x00, 0x00)},

This should fit on one line.  You can use up to 100-chars.

> +	{}
> +};
> +MODULE_DEVICE_TABLE(usb, nct6694_ids);
> +
> +static struct usb_driver nct6694_usb_driver = {
> +	.name	= "nct6694",

Odd spaces.

> +	.id_table = nct6694_ids,
> +	.probe = nct6694_usb_probe,
> +	.disconnect = nct6694_usb_disconnect,
> +};
> +

Remove this line.

> +module_usb_driver(nct6694_usb_driver);
> +
> +MODULE_DESCRIPTION("USB core driver for NCT6694");

This is not a USB driver.

> +MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");

Different to SoB.

> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/mfd/nct6694.h b/include/linux/mfd/nct6694.h
> new file mode 100644
> index 000000000000..8171f975761e
> --- /dev/null
> +++ b/include/linux/mfd/nct6694.h
> @@ -0,0 +1,102 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Nuvoton NCT6694 USB transaction and data structure.
> + *
> + * Copyright (C) 2024 Nuvoton Technology Corp.

At the top.

> + */
> +
> +#ifndef __MFD_NCT6694_H
> +#define __MFD_NCT6694_H
> +
> +#define NCT6694_VENDOR_ID	0x0416
> +#define NCT6694_PRODUCT_ID	0x200B
> +#define NCT6694_INT_IN_EP	0x81
> +#define NCT6694_BULK_IN_EP	0x02
> +#define NCT6694_BULK_OUT_EP	0x03
> +
> +#define NCT6694_HCTRL_SET	0x40
> +#define NCT6694_HCTRL_GET	0x80
> +
> +#define NCT6694_URB_TIMEOUT	1000
> +
> +enum nct6694_irq_id {
> +	NCT6694_IRQ_GPIO0 = 0,
> +	NCT6694_IRQ_GPIO1,
> +	NCT6694_IRQ_GPIO2,
> +	NCT6694_IRQ_GPIO3,
> +	NCT6694_IRQ_GPIO4,
> +	NCT6694_IRQ_GPIO5,
> +	NCT6694_IRQ_GPIO6,
> +	NCT6694_IRQ_GPIO7,
> +	NCT6694_IRQ_GPIO8,
> +	NCT6694_IRQ_GPIO9,
> +	NCT6694_IRQ_GPIOA,
> +	NCT6694_IRQ_GPIOB,
> +	NCT6694_IRQ_GPIOC,
> +	NCT6694_IRQ_GPIOD,
> +	NCT6694_IRQ_GPIOE,
> +	NCT6694_IRQ_GPIOF,
> +	NCT6694_IRQ_CAN0,
> +	NCT6694_IRQ_CAN1,
> +	NCT6694_IRQ_RTC,
> +	NCT6694_NR_IRQS,
> +};
> +
> +enum nct6694_response_err_status {
> +	NCT6694_NO_ERROR = 0,
> +	NCT6694_FORMAT_ERROR,
> +	NCT6694_RESERVED1,
> +	NCT6694_RESERVED2,
> +	NCT6694_NOT_SUPPORT_ERROR,
> +	NCT6694_NO_RESPONSE_ERROR,
> +	NCT6694_TIMEOUT_ERROR,
> +	NCT6694_PENDING,
> +};
> +
> +struct __packed nct6694_cmd_header {
> +	u8 rsv1;
> +	u8 mod;
> +	union __packed {
> +		__le16 offset;
> +		struct __packed {
> +			u8 cmd;
> +			u8 sel;
> +		};
> +	};
> +	u8 hctrl;
> +	u8 rsv2;
> +	__le16 len;
> +};
> +
> +struct __packed nct6694_response_header {
> +	u8 sequence_id;
> +	u8 sts;
> +	u8 reserved[4];
> +	__le16 len;
> +};
> +
> +union __packed nct6694_usb_msg {
> +	struct nct6694_cmd_header cmd_header;
> +	struct nct6694_response_header response_header;
> +};
> +
> +struct nct6694 {
> +	struct device *dev;
> +	struct irq_domain *domain;
> +	/* Mutex to protect access to the device */
> +	struct mutex access_lock;
> +	/* Mutex to protect access to the IRQ */
> +	struct mutex irq_lock;
> +	struct urb *int_in_urb;
> +	struct usb_device *udev;
> +	union nct6694_usb_msg *usb_msg;
> +	unsigned char *int_buffer;
> +	unsigned int irq_enable;
> +	/* Time in msec to wait for the URB to the complete */
> +	long timeout;

timeout_ms

> +};
> +
> +int nct6694_read_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf);
> +int nct6694_write_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf);
> +
> +#endif
> -- 
> 2.34.1
> 

-- 
Lee Jones [李琼斯]

Dear Lee,

Thank you for reviewing,

Lee Jones <lee@kernel.org> 於 2025年3月7日 週五 上午9:15寫道：
>
> On Tue, 25 Feb 2025, Ming Yu wrote:
>
> > The Nuvoton NCT6694 is a peripheral expander with 16 GPIO chips,
> > 6 I2C controllers, 2 CANfd controllers, 2 Watchdog timers, ADC,
> > PWM, and RTC.
>
> This needs to go into the Kconfig help passage.
>

Okay, I will move these to Kconfig in the next patch.

> > This driver implements USB device functionality and shares the
> > chip's peripherals as a child device.
>
> This driver doesn't implement USB functionality.
>

Fix it in v9.

> > Each child device can use the USB functions nct6694_read_msg()
> > and nct6694_write_msg() to issue a command. They can also request
> > interrupt that will be called when the USB device receives its
> > interrupt pipe.
> >
> > Signed-off-by: Ming Yu <a0282524688@gmail.com>
>
> Why aren't you signing off with your work address?
>

Fix it in v9.

> > ---
> >  MAINTAINERS                 |   7 +
> >  drivers/mfd/Kconfig         |  18 ++
> >  drivers/mfd/Makefile        |   2 +
> >  drivers/mfd/nct6694.c       | 378 ++++++++++++++++++++++++++++++++++++
> >  include/linux/mfd/nct6694.h | 102 ++++++++++
> >  5 files changed, 507 insertions(+)
> >  create mode 100644 drivers/mfd/nct6694.c
> >  create mode 100644 include/linux/mfd/nct6694.h
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 873aa2cce4d7..c700a0b96960 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -16918,6 +16918,13 @@ F:   drivers/nubus/
> >  F:   include/linux/nubus.h
> >  F:   include/uapi/linux/nubus.h
> >
> > +NUVOTON NCT6694 MFD DRIVER
> > +M:   Ming Yu <tmyu0@nuvoton.com>
> > +L:   linux-kernel@vger.kernel.org
>
> This is the default list.  You shouldn't need to add that here.
>

Remove it in v9.

> > +S:   Supported
> > +F:   drivers/mfd/nct6694.c
> > +F:   include/linux/mfd/nct6694.h
> > +
> >  NVIDIA (rivafb and nvidiafb) FRAMEBUFFER DRIVER
> >  M:   Antonino Daplas <adaplas@gmail.com>
> >  L:   linux-fbdev@vger.kernel.org
> > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> > index 6b0682af6e32..c97a2bdcea0b 100644
> > --- a/drivers/mfd/Kconfig
> > +++ b/drivers/mfd/Kconfig
> > @@ -1045,6 +1045,24 @@ config MFD_MENF21BMC
> >         This driver can also be built as a module. If so the module
> >         will be called menf21bmc.
> >
> > +config MFD_NCT6694
> > +     tristate "Nuvoton NCT6694 support"
> > +     select MFD_CORE
> > +     depends on USB
> > +     help
> > +       This enables support for the Nuvoton USB device NCT6694, which shares
> > +       peripherals.
> > +
> > +       This driver provides core APIs to access the NCT6694 hardware
> > +       monitoring and control features.
> > +
> > +       The NCT6694 is a versatile multi-function device that supports
>
> Please drop the term multi-function device and replace it what a proper
> description of the devices.
>

Fix it in v9.

> > +       functionalities such as GPIO, I2C, CAN, WDT, HWMON, and RTC
> > +       management.
>
> All of these line breaks should be removed.
>

Fix these in v9.

> > +       Additional drivers must be enabled to utilize the specific
> > +       functionalities of the device.
> > +
> >  config MFD_OCELOT
> >       tristate "Microsemi Ocelot External Control Support"
> >       depends on SPI_MASTER
> > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> > index 9220eaf7cf12..7725b732e265 100644
> > --- a/drivers/mfd/Makefile
> > +++ b/drivers/mfd/Makefile
> > @@ -121,6 +121,8 @@ obj-$(CONFIG_MFD_MC13XXX) += mc13xxx-core.o
> >  obj-$(CONFIG_MFD_MC13XXX_SPI)        += mc13xxx-spi.o
> >  obj-$(CONFIG_MFD_MC13XXX_I2C)        += mc13xxx-i2c.o
> >
> > +obj-$(CONFIG_MFD_NCT6694)    += nct6694.o
> > +
> >  obj-$(CONFIG_MFD_CORE)               += mfd-core.o
> >
> >  ocelot-soc-objs                      := ocelot-core.o ocelot-spi.o
> > diff --git a/drivers/mfd/nct6694.c b/drivers/mfd/nct6694.c
> > new file mode 100644
> > index 000000000000..c82457679ca6
> > --- /dev/null
> > +++ b/drivers/mfd/nct6694.c
> > @@ -0,0 +1,378 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Nuvoton NCT6694 core driver using USB interface to provide
> > + * access to the NCT6694 hardware monitoring and control features.
> > + *
> > + * The NCT6694 is a versatile multi-function device that supports
>
> Here too.
>

Fix it in v9.

> > + * functionalities such as GPIO, I2C, CAN, WDT, HWMON and RTC
> > + * management.
> > + *
> > + * Copyright (C) 2024 Nuvoton Technology Corp.
>
> This goes at the top.
>

Fix it in v9.

> > + */
> > +
> > +#include <linux/bits.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/irq.h>
> > +#include <linux/irqdomain.h>
> > +#include <linux/kernel.h>
> > +#include <linux/mfd/core.h>
> > +#include <linux/mfd/nct6694.h>
> > +#include <linux/module.h>
> > +#include <linux/slab.h>
> > +#include <linux/usb.h>
> > +
> > +static const struct mfd_cell nct6694_dev[] = {
> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x0),
>
> "-gpio" usually goes on the end.
>

Fix it in v9.

> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x1),
>
> IDs are usually given in base-10.
>

Fix it in v9.

> Why are you manually adding the device IDs?
>
> PLATFORM_DEVID_AUTO doesn't work for you?
>

I need to manage these IDs to ensure that child devices can be
properly utilized within their respective modules.

> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x2),
> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x3),
> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x4),
> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x5),
> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x6),
> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x7),
> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x8),
> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x9),
> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xA),
> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xB),
> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xC),
> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xD),
> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xE),
> > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xF),
> > +
> > +     MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x0),
> > +     MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x1),
> > +     MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x2),
> > +     MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x3),
> > +     MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x4),
> > +     MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x5),
> > +
> > +     MFD_CELL_BASIC("nct6694_canfd", NULL, NULL, 0, 0x0),
>
> Why has the naming convention changed here?
>

I originally expected the child devices name to directly match its
driver name. Do you think it would be better to standardize the naming
as "nct6694-xxx" ?

> > +     MFD_CELL_BASIC("nct6694_canfd", NULL, NULL, 0, 0x1),
> > +
> > +     MFD_CELL_BASIC("nct6694_wdt", NULL, NULL, 0, 0x0),
> > +     MFD_CELL_BASIC("nct6694_wdt", NULL, NULL, 0, 0x1),
> > +
> > +     MFD_CELL_NAME("nct6694-hwmon"),
> > +     MFD_CELL_NAME("rtc-nct6694"),
>
> There doesn't seem to be any consistency here.
>

Do you think these two should be changed to use MFD_CELL_BASIC()?

> > +};
> > +
> > +static int nct6694_response_err_handling(struct nct6694 *nct6694,
>
> > +{
> > +     switch (err_status) {
> > +     case NCT6694_NO_ERROR:
> > +             return err_status;
>
> This is odd since you already know this will be 0.
>

Fix it in v9.

> > +     case NCT6694_NOT_SUPPORT_ERROR:
> > +             dev_warn(nct6694->dev, "Command is not supported!\n");
>
> Why not dev_err()?
>

Fix it in v9.

> > +             break;
> > +     case NCT6694_NO_RESPONSE_ERROR:
> > +             dev_warn(nct6694->dev, "Command received no response!\n");
> > +             break;
> > +     case NCT6694_TIMEOUT_ERROR:
> > +             dev_warn(nct6694->dev, "Command timed out!\n");
> > +             break;
> > +     case NCT6694_PENDING:
> > +             dev_warn(nct6694->dev, "Command is pending!\n");
>
> Is this an error?
>

Yes, I will fix it to dev_err() in the next patch.

> > +             break;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +
> > +     return -EIO;
> > +}
> > +
> > +int nct6694_read_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf)
> > +{
> > +     union nct6694_usb_msg *msg = nct6694->usb_msg;
> > +     int tx_len, rx_len, ret;
> > +
> > +     guard(mutex)(&nct6694->access_lock);
> > +
> > +     /* Send command packet to USB device */
>
> This doesn't really describe the next 2 lines.
>
> Move it down?
>

Fix it in v9.

> > +     memcpy(&msg->cmd_header, cmd_hd, sizeof(*cmd_hd));
> > +     msg->cmd_header.hctrl = NCT6694_HCTRL_GET;
> > +
> > +     ret = usb_bulk_msg(nct6694->udev,
>
> Since you use nct6694->udev a bunch - sometimes twice in the same call,
> it might be nicer to pull it into it's own variable instead of
> dereferencing it all the time.
>

Fix it in v9.

> > +                        usb_sndbulkpipe(nct6694->udev, NCT6694_BULK_OUT_EP),
> > +                        &msg->cmd_header, sizeof(*msg), &tx_len,
> > +                        nct6694->timeout);
> > +     if (ret)
> > +             return ret;
> > +
> > +     /* Receive response packet from USB device */
> > +     ret = usb_bulk_msg(nct6694->udev,
> > +                        usb_rcvbulkpipe(nct6694->udev, NCT6694_BULK_IN_EP),
> > +                        &msg->response_header, sizeof(*msg), &rx_len,
>
> How can you read sizeof(*msg) Bytes (22?) into the smaller
> response_header (16?) attribute?
>

The size of (*msg) is the same as command_header and response_header (8 bytes).

> > +                        nct6694->timeout);
> > +     if (ret)
> > +             return ret;
> > +
> > +     /* Receive data packet from USB device */
> > +     ret = usb_bulk_msg(nct6694->udev,
> > +                        usb_rcvbulkpipe(nct6694->udev, NCT6694_BULK_IN_EP),
> > +                        buf, le16_to_cpu(cmd_hd->len), &rx_len,
> > +                        nct6694->timeout);
> > +     if (ret)
> > +             return ret;
> > +
> > +     if (rx_len != le16_to_cpu(cmd_hd->len)) {
> > +             dev_err(nct6694->dev, "Expected received length %d, but got %d\n",
> > +                     le16_to_cpu(cmd_hd->len), rx_len);
> > +             return -EIO;
> > +     }
> > +
> > +     return nct6694_response_err_handling(nct6694, msg->response_header.sts);
> > +}
> > +EXPORT_SYMBOL(nct6694_read_msg);
> > +
> > +int nct6694_write_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf)
> > +{
> > +     union nct6694_usb_msg *msg = nct6694->usb_msg;
> > +     int tx_len, rx_len, ret;
> > +
> > +     guard(mutex)(&nct6694->access_lock);
> > +
> > +     /* Send command packet to USB device */
> > +     memcpy(&msg->cmd_header, cmd_hd, sizeof(*cmd_hd));
> > +     msg->cmd_header.hctrl = NCT6694_HCTRL_SET;
> > +
> > +     ret = usb_bulk_msg(nct6694->udev,
> > +                        usb_sndbulkpipe(nct6694->udev, NCT6694_BULK_OUT_EP),
> > +                        &msg->cmd_header, sizeof(*msg), &tx_len,
> > +                        nct6694->timeout);
> > +     if (ret)
> > +             return ret;
> > +
> > +     /* Send data packet to USB device */
> > +     ret = usb_bulk_msg(nct6694->udev,
> > +                        usb_sndbulkpipe(nct6694->udev, NCT6694_BULK_OUT_EP),
> > +                        buf, le16_to_cpu(cmd_hd->len), &tx_len,
> > +                        nct6694->timeout);
> > +     if (ret)
> > +             return ret;
> > +
> > +     /* Receive response packet from USB device */
> > +     ret = usb_bulk_msg(nct6694->udev,
> > +                        usb_rcvbulkpipe(nct6694->udev, NCT6694_BULK_IN_EP),
> > +                        &msg->response_header, sizeof(*msg), &rx_len,
> > +                        nct6694->timeout);
> > +     if (ret)
> > +             return ret;
> > +
> > +     /* Receive data packet from USB device */
> > +     ret = usb_bulk_msg(nct6694->udev,
> > +                        usb_rcvbulkpipe(nct6694->udev, NCT6694_BULK_IN_EP),
> > +                        buf, le16_to_cpu(cmd_hd->len), &rx_len,
> > +                        nct6694->timeout);
> > +     if (ret)
> > +             return ret;
> > +
> > +     if (rx_len != le16_to_cpu(cmd_hd->len)) {
> > +             dev_err(nct6694->dev, "Expected transmitted length %d, but got %d\n",
> > +                     le16_to_cpu(cmd_hd->len), rx_len);
> > +             return -EIO;
> > +     }
> > +
> > +     return nct6694_response_err_handling(nct6694, msg->response_header.sts);
> > +}
> > +EXPORT_SYMBOL(nct6694_write_msg);
> > +
> > +static void usb_int_callback(struct urb *urb)
> > +{
> > +     struct nct6694 *nct6694 = urb->context;
> > +     unsigned int *int_status = urb->transfer_buffer;
> > +     int ret;
> > +
> > +     switch (urb->status) {
> > +     case 0:
> > +             break;
> > +     case -ECONNRESET:
> > +     case -ENOENT:
> > +     case -ESHUTDOWN:
> > +             return;
> > +     default:
> > +             generic_handle_irq_safe(irq_find_mapping(nct6694->domain, irq));
> > +             *int_status &= ~BIT(irq);
> > +     }
> > +
> > +resubmit:
> > +     ret = usb_submit_urb(urb, GFP_ATOMIC);
> > +     if (ret)
> > +             dev_dbg(nct6694->dev, "%s: Failed to resubmit urb, status %pe",
>
> Why debug?
>

Excuse me, do you think it should change to dev_err()?

> > +                     __func__, ERR_PTR(ret));
>
> Remove the __func__ part.
>

Understood.

> > +}
> > +
...
> > +static int nct6694_usb_probe(struct usb_interface *iface,
> > +                          const struct usb_device_id *id)
> > +{
> > +     struct usb_device *udev = interface_to_usbdev(iface);
> > +     struct usb_endpoint_descriptor *int_endpoint;
> > +     struct usb_host_interface *interface;
> > +     struct device *dev = &iface->dev;
> > +     struct nct6694 *nct6694;
> > +     int pipe, maxp;
> > +     int ret;
> > +
> > +     nct6694 = devm_kzalloc(dev, sizeof(*nct6694), GFP_KERNEL);
> > +     if (!nct6694)
> > +             return -ENOMEM;
> > +
> > +     pipe = usb_rcvintpipe(udev, NCT6694_INT_IN_EP);
> > +     maxp = usb_maxpacket(udev, pipe);
> > +
> > +     nct6694->usb_msg = devm_kzalloc(dev, sizeof(union nct6694_usb_msg), GFP_KERNEL);
> > +     if (!nct6694->usb_msg)
> > +             return -ENOMEM;
> > +
> > +     nct6694->int_buffer = devm_kzalloc(dev, maxp, GFP_KERNEL);
> > +     if (!nct6694->int_buffer)
> > +             return -ENOMEM;
> > +
> > +     nct6694->int_in_urb = usb_alloc_urb(0, GFP_KERNEL);
> > +     if (!nct6694->int_in_urb)
> > +             return -ENOMEM;
> > +
> > +     nct6694->domain = irq_domain_add_simple(NULL, NCT6694_NR_IRQS, 0,
> > +                                             &nct6694_irq_domain_ops,
> > +                                             nct6694);
> > +     if (!nct6694->domain) {
> > +             ret = -ENODEV;
> > +             goto err_urb;
> > +     }
> > +
> > +     nct6694->dev = dev;
> > +     nct6694->udev = udev;
> > +     nct6694->timeout = NCT6694_URB_TIMEOUT; /* Wait until URB completes */
>
> No need to save this known value.
>

Understood, I will drop it in the next patch.

> > +     ret = devm_mutex_init(dev, &nct6694->access_lock);
> > +     if (ret)
> > +             goto err_urb;
> > +
> > +     ret = devm_mutex_init(dev, &nct6694->irq_lock);
> > +     if (ret)
> > +             goto err_urb;
> > +
> > +     interface = iface->cur_altsetting;
> > +     int_endpoint = &interface->endpoint[0].desc;
> > +     if (!usb_endpoint_is_int_in(int_endpoint)) {
> > +             ret = -ENODEV;
> > +             goto err_urb;
> > +     }
> > +     usb_fill_int_urb(nct6694->int_in_urb, udev, pipe,
> > +                      nct6694->int_buffer, maxp, usb_int_callback,
> > +                      nct6694, int_endpoint->bInterval);
> > +     ret = usb_submit_urb(nct6694->int_in_urb, GFP_KERNEL);
> > +     if (ret)
> > +             goto err_urb;
>
> Please unsquash these calls - space them out.
>

Fix these in v9.

> > +
> > +     usb_set_intfdata(iface, nct6694);
> > +
> > +     ret = mfd_add_hotplug_devices(dev, nct6694_dev, ARRAY_SIZE(nct6694_dev));
> > +     if (ret)
> > +             goto err_mfd;
> > +
> > +     return 0;
> > +
> > +err_mfd:
> > +     usb_kill_urb(nct6694->int_in_urb);
> > +err_urb:
> > +     usb_free_urb(nct6694->int_in_urb);
> > +     return ret;
> > +}
> > +
> > +static void nct6694_usb_disconnect(struct usb_interface *iface)
> > +{
> > +     struct nct6694 *nct6694 = usb_get_intfdata(iface);
> > +
> > +     mfd_remove_devices(nct6694->dev);
> > +     usb_kill_urb(nct6694->int_in_urb);
> > +     usb_free_urb(nct6694->int_in_urb);
> > +}
> > +
> > +static const struct usb_device_id nct6694_ids[] = {
> > +     { USB_DEVICE_AND_INTERFACE_INFO(NCT6694_VENDOR_ID,
> > +                                     NCT6694_PRODUCT_ID,
> > +                                     0xFF, 0x00, 0x00)},
>
> This should fit on one line.  You can use up to 100-chars.
>

Fix it in v9.

> > +     {}
> > +};
> > +MODULE_DEVICE_TABLE(usb, nct6694_ids);
> > +
> > +static struct usb_driver nct6694_usb_driver = {
> > +     .name   = "nct6694",
>
> Odd spaces.
>

Fix it in v9.

> > +     .id_table = nct6694_ids,
> > +     .probe = nct6694_usb_probe,
> > +     .disconnect = nct6694_usb_disconnect,
> > +};
> > +
>
> Remove this line.
>

Fix it in v9.

> > +module_usb_driver(nct6694_usb_driver);
> > +
> > +MODULE_DESCRIPTION("USB core driver for NCT6694");
>
> This is not a USB driver.
>

Fix it in v9.

> > +MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
>
> Different to SoB.
>

Fix it in v9.

> > +MODULE_LICENSE("GPL");
> > diff --git a/include/linux/mfd/nct6694.h b/include/linux/mfd/nct6694.h
> > new file mode 100644
> > index 000000000000..8171f975761e
> > --- /dev/null
> > +++ b/include/linux/mfd/nct6694.h
> > @@ -0,0 +1,102 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * Nuvoton NCT6694 USB transaction and data structure.
> > + *
> > + * Copyright (C) 2024 Nuvoton Technology Corp.
>
> At the top.
>

Fix it in v9.

> > + */
> > +


Best regards,
Ming

On Mon, 17 Mar 2025, Ming Yu wrote:

> Dear Lee,
> 
> Thank you for reviewing,
> 
> Lee Jones <lee@kernel.org> 於 2025年3月7日 週五 上午9:15寫道：
> >
> > On Tue, 25 Feb 2025, Ming Yu wrote:
> >
> > > The Nuvoton NCT6694 is a peripheral expander with 16 GPIO chips,
> > > 6 I2C controllers, 2 CANfd controllers, 2 Watchdog timers, ADC,
> > > PWM, and RTC.
> >
> > This needs to go into the Kconfig help passage.
> >
> 
> Okay, I will move these to Kconfig in the next patch.
> 
> > > This driver implements USB device functionality and shares the
> > > chip's peripherals as a child device.
> >
> > This driver doesn't implement USB functionality.
> >
> 
> Fix it in v9.
> 
> > > Each child device can use the USB functions nct6694_read_msg()
> > > and nct6694_write_msg() to issue a command. They can also request
> > > interrupt that will be called when the USB device receives its
> > > interrupt pipe.
> > >
> > > Signed-off-by: Ming Yu <a0282524688@gmail.com>
> >
> > Why aren't you signing off with your work address?
> >
> 
> Fix it in v9.
> 
> > > ---
> > >  MAINTAINERS                 |   7 +
> > >  drivers/mfd/Kconfig         |  18 ++
> > >  drivers/mfd/Makefile        |   2 +
> > >  drivers/mfd/nct6694.c       | 378 ++++++++++++++++++++++++++++++++++++
> > >  include/linux/mfd/nct6694.h | 102 ++++++++++
> > >  5 files changed, 507 insertions(+)
> > >  create mode 100644 drivers/mfd/nct6694.c
> > >  create mode 100644 include/linux/mfd/nct6694.h
> > >
> > > diff --git a/MAINTAINERS b/MAINTAINERS
> > > index 873aa2cce4d7..c700a0b96960 100644
> > > --- a/MAINTAINERS
> > > +++ b/MAINTAINERS
> > > @@ -16918,6 +16918,13 @@ F:   drivers/nubus/
> > >  F:   include/linux/nubus.h
> > >  F:   include/uapi/linux/nubus.h
> > >
> > > +NUVOTON NCT6694 MFD DRIVER
> > > +M:   Ming Yu <tmyu0@nuvoton.com>
> > > +L:   linux-kernel@vger.kernel.org
> >
> > This is the default list.  You shouldn't need to add that here.
> 
> Remove it in v9.

Please snip everything that you agree with.

> > > +S:   Supported
> > > +F:   drivers/mfd/nct6694.c
> > > +F:   include/linux/mfd/nct6694.h
> > > +
> > >  NVIDIA (rivafb and nvidiafb) FRAMEBUFFER DRIVER
> > >  M:   Antonino Daplas <adaplas@gmail.com>
> > >  L:   linux-fbdev@vger.kernel.org

[...]

> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x1),
> >
> > IDs are usually given in base-10.
> >
> 
> Fix it in v9.
> 
> > Why are you manually adding the device IDs?
> >
> > PLATFORM_DEVID_AUTO doesn't work for you?
> >
> 
> I need to manage these IDs to ensure that child devices can be
> properly utilized within their respective modules.

How?  Please explain.

This numbering looks sequential and arbitrary.

What does PLATFORM_DEVID_AUTO do differently such that it is not useful?

> 
> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x2),
> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x3),
> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x4),
> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x5),
> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x6),
> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x7),
> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x8),
> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x9),
> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xA),
> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xB),
> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xC),
> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xD),
> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xE),
> > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xF),

> > > +
> > > +     MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x0),
> > > +     MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x1),
> > > +     MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x2),
> > > +     MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x3),
> > > +     MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x4),
> > > +     MFD_CELL_BASIC("i2c-nct6694", NULL, NULL, 0, 0x5),
> > > +
> > > +     MFD_CELL_BASIC("nct6694_canfd", NULL, NULL, 0, 0x0),
> >
> > Why has the naming convention changed here?
> >
> 
> I originally expected the child devices name to directly match its
> driver name. Do you think it would be better to standardize the naming
> as "nct6694-xxx" ?

Yes, that is the usual procedure.

> > > +     MFD_CELL_BASIC("nct6694_canfd", NULL, NULL, 0, 0x1),
> > > +
> > > +     MFD_CELL_BASIC("nct6694_wdt", NULL, NULL, 0, 0x0),
> > > +     MFD_CELL_BASIC("nct6694_wdt", NULL, NULL, 0, 0x1),
> > > +
> > > +     MFD_CELL_NAME("nct6694-hwmon"),
> > > +     MFD_CELL_NAME("rtc-nct6694"),
> >
> > There doesn't seem to be any consistency here.
> >
> 
> Do you think these two should be changed to use MFD_CELL_BASIC()?

No.  I mean with the device nomenclature.

[...]

> > > +static void usb_int_callback(struct urb *urb)
> > > +{
> > > +     struct nct6694 *nct6694 = urb->context;
> > > +     unsigned int *int_status = urb->transfer_buffer;
> > > +     int ret;
> > > +
> > > +     switch (urb->status) {
> > > +     case 0:
> > > +             break;
> > > +     case -ECONNRESET:
> > > +     case -ENOENT:
> > > +     case -ESHUTDOWN:
> > > +             return;
> > > +     default:
> > > +             generic_handle_irq_safe(irq_find_mapping(nct6694->domain, irq));
> > > +             *int_status &= ~BIT(irq);
> > > +     }
> > > +
> > > +resubmit:
> > > +     ret = usb_submit_urb(urb, GFP_ATOMIC);
> > > +     if (ret)
> > > +             dev_dbg(nct6694->dev, "%s: Failed to resubmit urb, status %pe",
> >
> > Why debug?
> >
> 
> Excuse me, do you think it should change to dev_err()?

Probably a dev_warn() since you are not propagating the error.

Is this okay by the way?  Is it okay to fail?

-- 
Lee Jones [李琼斯]

Lee Jones <lee@kernel.org> 於 2025年3月20日 週四 下午10:50寫道：
>
...
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x1),
> > >
> > > IDs are usually given in base-10.
> > >
> >
> > Fix it in v9.
> >
> > > Why are you manually adding the device IDs?
> > >
> > > PLATFORM_DEVID_AUTO doesn't work for you?
> > >
> >
> > I need to manage these IDs to ensure that child devices can be
> > properly utilized within their respective modules.
>
> How?  Please explain.
>
> This numbering looks sequential and arbitrary.
>
> What does PLATFORM_DEVID_AUTO do differently such that it is not useful?
>

As far as I know, PLATFORM_DEVID_AUTO assigns dynamic IDs to devices,
but I need fixed IDs.
For example, the GPIO driver relies on these IDs to determine the
group, allowing the firmware to identify which GPIO group to operate
on through the API.

> >
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x2),
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x3),
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x4),
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x5),
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x6),
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x7),
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x8),
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x9),
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xA),
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xB),
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xC),
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xD),
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xE),
> > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xF),


Thanks,
Ming

On Wed, 26 Mar 2025, Ming Yu wrote:

> Lee Jones <lee@kernel.org> 於 2025年3月20日 週四 下午10:50寫道：
> >
> ...
> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x1),
> > > >
> > > > IDs are usually given in base-10.
> > > >
> > >
> > > Fix it in v9.
> > >
> > > > Why are you manually adding the device IDs?
> > > >
> > > > PLATFORM_DEVID_AUTO doesn't work for you?
> > > >
> > >
> > > I need to manage these IDs to ensure that child devices can be
> > > properly utilized within their respective modules.
> >
> > How?  Please explain.
> >
> > This numbering looks sequential and arbitrary.
> >
> > What does PLATFORM_DEVID_AUTO do differently such that it is not useful?
> >
> 
> As far as I know, PLATFORM_DEVID_AUTO assigns dynamic IDs to devices,
> but I need fixed IDs.
> For example, the GPIO driver relies on these IDs to determine the
> group, allowing the firmware to identify which GPIO group to operate
> on through the API.

PLATFORM_DEVID_AUTO will allocate IDs 0 through 16, the same as you've
done here.  These lines do not have any differentiating attributes, so
either way we are not allocating specific IDs to specific pieces of the
H/W.  I still do not understand why you need to allocate them manually.

> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x2),
> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x3),
> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x4),
> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x5),
> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x6),
> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x7),
> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x8),
> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x9),
> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xA),
> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xB),
> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xC),
> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xD),
> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xE),
> > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0xF),
> 
> 
> Thanks,
> Ming

-- 
Lee Jones [李琼斯]

Lee Jones <lee@kernel.org> 於 2025年4月4日 週五 下午10:21寫道：
>
> > ...
> > > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x1),
> > > > >
> > > > > IDs are usually given in base-10.
> > > > >
> > > >
> > > > Fix it in v9.
> > > >
> > > > > Why are you manually adding the device IDs?
> > > > >
> > > > > PLATFORM_DEVID_AUTO doesn't work for you?
> > > > >
> > > >
> > > > I need to manage these IDs to ensure that child devices can be
> > > > properly utilized within their respective modules.
> > >
> > > How?  Please explain.
> > >
> > > This numbering looks sequential and arbitrary.
> > >
> > > What does PLATFORM_DEVID_AUTO do differently such that it is not useful?
> > >
> >
> > As far as I know, PLATFORM_DEVID_AUTO assigns dynamic IDs to devices,
> > but I need fixed IDs.
> > For example, the GPIO driver relies on these IDs to determine the
> > group, allowing the firmware to identify which GPIO group to operate
> > on through the API.
>
> PLATFORM_DEVID_AUTO will allocate IDs 0 through 16, the same as you've
> done here.  These lines do not have any differentiating attributes, so
> either way we are not allocating specific IDs to specific pieces of the
> H/W.  I still do not understand why you need to allocate them manually.
>

I'm using PLATFORM_DEVID_AUTO to allocate child device IDs with
MFD_CELL_NAME(), like this:

static const struct mfd_cell nct6694_dev[] = {
    MFD_CELL_NAME("nct6694-gpio"),
    MFD_CELL_NAME("nct6694-gpio"),
    ......
    MFD_CELL_NAME("nct6694-gpio"),
    MFD_CELL_NAME("nct6694-i2c"),
    MFD_CELL_NAME("nct6694-i2c"),
    ......
    MFD_CELL_NAME("nct6694-i2c"),
    ......
};

For example, the device IDs retrieved in gpio-nct6694.c is 1~16, and
i2c-nct6694.c is 17~22. Does this mean each driver should
independently handle its dynamically assigned IDs?
Additionally, I originally referred to cgbc-core.c with i2c-cgbc.c,
and ab8500-core.c with pwm-ab8500.c for associating child devices. Do
you think this approach is appropriate in my case?


Thanks,
Ming

On Mon, 07 Apr 2025, Ming Yu wrote:

> Lee Jones <lee@kernel.org> 於 2025年4月4日 週五 下午10:21寫道：
> >
> > > ...
> > > > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x1),
> > > > > >
> > > > > > IDs are usually given in base-10.
> > > > > >
> > > > >
> > > > > Fix it in v9.
> > > > >
> > > > > > Why are you manually adding the device IDs?
> > > > > >
> > > > > > PLATFORM_DEVID_AUTO doesn't work for you?
> > > > > >
> > > > >
> > > > > I need to manage these IDs to ensure that child devices can be
> > > > > properly utilized within their respective modules.
> > > >
> > > > How?  Please explain.
> > > >
> > > > This numbering looks sequential and arbitrary.
> > > >
> > > > What does PLATFORM_DEVID_AUTO do differently such that it is not useful?
> > > >
> > >
> > > As far as I know, PLATFORM_DEVID_AUTO assigns dynamic IDs to devices,
> > > but I need fixed IDs.
> > > For example, the GPIO driver relies on these IDs to determine the
> > > group, allowing the firmware to identify which GPIO group to operate
> > > on through the API.
> >
> > PLATFORM_DEVID_AUTO will allocate IDs 0 through 16, the same as you've
> > done here.  These lines do not have any differentiating attributes, so
> > either way we are not allocating specific IDs to specific pieces of the
> > H/W.  I still do not understand why you need to allocate them manually.
> >
> 
> I'm using PLATFORM_DEVID_AUTO to allocate child device IDs with
> MFD_CELL_NAME(), like this:
> 
> static const struct mfd_cell nct6694_dev[] = {
>     MFD_CELL_NAME("nct6694-gpio"),
>     MFD_CELL_NAME("nct6694-gpio"),
>     ......
>     MFD_CELL_NAME("nct6694-gpio"),
>     MFD_CELL_NAME("nct6694-i2c"),
>     MFD_CELL_NAME("nct6694-i2c"),
>     ......
>     MFD_CELL_NAME("nct6694-i2c"),
>     ......
> };
> 
> For example, the device IDs retrieved in gpio-nct6694.c is 1~16, and
> i2c-nct6694.c is 17~22. Does this mean each driver should
> independently handle its dynamically assigned IDs?
> Additionally, I originally referred to cgbc-core.c with i2c-cgbc.c,
> and ab8500-core.c with pwm-ab8500.c for associating child devices. Do
> you think this approach is appropriate in my case?

Yes, if you _need_ the ranges to start from 0, then you will have to
call mfd_add_devices() separately on those ranges.  Otherwise one range
will follow directly on to another range.

But wait, you're using mfd_add_hotplug_devices(), which means you are
using PLATFORM_DEVID_AUTO.  So your .id values that you've added are
being ignored anyway.  Thus, if you have tested that this works, you
don't need them anyway, right?

-- 
Lee Jones [李琼斯]

Lee Jones <lee@kernel.org> 於 2025年4月10日 週四 下午4:21寫道：
>
> On Mon, 07 Apr 2025, Ming Yu wrote:
>
> > Lee Jones <lee@kernel.org> 於 2025年4月4日 週五 下午10:21寫道：
> > >
> > > > ...
> > > > > > > > +     MFD_CELL_BASIC("gpio-nct6694", NULL, NULL, 0, 0x1),
> > > > > > >
> > > > > > > IDs are usually given in base-10.
> > > > > > >
> > > > > >
> > > > > > Fix it in v9.
> > > > > >
> > > > > > > Why are you manually adding the device IDs?
> > > > > > >
> > > > > > > PLATFORM_DEVID_AUTO doesn't work for you?
> > > > > > >
> > > > > >
> > > > > > I need to manage these IDs to ensure that child devices can be
> > > > > > properly utilized within their respective modules.
> > > > >
> > > > > How?  Please explain.
> > > > >
> > > > > This numbering looks sequential and arbitrary.
> > > > >
> > > > > What does PLATFORM_DEVID_AUTO do differently such that it is not useful?
> > > > >
> > > >
> > > > As far as I know, PLATFORM_DEVID_AUTO assigns dynamic IDs to devices,
> > > > but I need fixed IDs.
> > > > For example, the GPIO driver relies on these IDs to determine the
> > > > group, allowing the firmware to identify which GPIO group to operate
> > > > on through the API.
> > >
> > > PLATFORM_DEVID_AUTO will allocate IDs 0 through 16, the same as you've
> > > done here.  These lines do not have any differentiating attributes, so
> > > either way we are not allocating specific IDs to specific pieces of the
> > > H/W.  I still do not understand why you need to allocate them manually.
> > >
> >
> > I'm using PLATFORM_DEVID_AUTO to allocate child device IDs with
> > MFD_CELL_NAME(), like this:
> >
> > static const struct mfd_cell nct6694_dev[] = {
> >     MFD_CELL_NAME("nct6694-gpio"),
> >     MFD_CELL_NAME("nct6694-gpio"),
> >     ......
> >     MFD_CELL_NAME("nct6694-gpio"),
> >     MFD_CELL_NAME("nct6694-i2c"),
> >     MFD_CELL_NAME("nct6694-i2c"),
> >     ......
> >     MFD_CELL_NAME("nct6694-i2c"),
> >     ......
> > };
> >
> > For example, the device IDs retrieved in gpio-nct6694.c is 1~16, and
> > i2c-nct6694.c is 17~22. Does this mean each driver should
> > independently handle its dynamically assigned IDs?
> > Additionally, I originally referred to cgbc-core.c with i2c-cgbc.c,
> > and ab8500-core.c with pwm-ab8500.c for associating child devices. Do
> > you think this approach is appropriate in my case?
>
> Yes, if you _need_ the ranges to start from 0, then you will have to
> call mfd_add_devices() separately on those ranges.  Otherwise one range
> will follow directly on to another range.
>
> But wait, you're using mfd_add_hotplug_devices(), which means you are
> using PLATFORM_DEVID_AUTO.  So your .id values that you've added are
> being ignored anyway.  Thus, if you have tested that this works, you
> don't need them anyway, right?
>

Yes, it uses PLATFORM_DEVID_AUTO, but in my implementation, the
sub-devices use cell->id instead of platform_device->id, so it doesn't
affect the current behavior.

However, if you think there's a better approach or that this should be
changed for consistency or correctness, I'm happy to update it, please
let me know your recommendation.


Thanks,
Ming

On 25.02.2025 16:16:38, Ming Yu wrote:

[...]

> +static int nct6694_usb_probe(struct usb_interface *iface,
> +			     const struct usb_device_id *id)
> +{
> +	struct usb_device *udev = interface_to_usbdev(iface);
> +	struct usb_endpoint_descriptor *int_endpoint;
> +	struct usb_host_interface *interface;
> +	struct device *dev = &iface->dev;
> +	struct nct6694 *nct6694;
> +	int pipe, maxp;
> +	int ret;
> +
> +	nct6694 = devm_kzalloc(dev, sizeof(*nct6694), GFP_KERNEL);
> +	if (!nct6694)
> +		return -ENOMEM;
> +
> +	pipe = usb_rcvintpipe(udev, NCT6694_INT_IN_EP);
> +	maxp = usb_maxpacket(udev, pipe);
> +
> +	nct6694->usb_msg = devm_kzalloc(dev, sizeof(union nct6694_usb_msg), GFP_KERNEL);
> +	if (!nct6694->usb_msg)
> +		return -ENOMEM;
> +
> +	nct6694->int_buffer = devm_kzalloc(dev, maxp, GFP_KERNEL);
> +	if (!nct6694->int_buffer)
> +		return -ENOMEM;
> +
> +	nct6694->int_in_urb = usb_alloc_urb(0, GFP_KERNEL);
> +	if (!nct6694->int_in_urb)
> +		return -ENOMEM;
> +
> +	nct6694->domain = irq_domain_add_simple(NULL, NCT6694_NR_IRQS, 0,
> +						&nct6694_irq_domain_ops,
> +						nct6694);
> +	if (!nct6694->domain) {
> +		ret = -ENODEV;
> +		goto err_urb;
> +	}
> +
> +	nct6694->dev = dev;
> +	nct6694->udev = udev;
> +	nct6694->timeout = NCT6694_URB_TIMEOUT;	/* Wait until URB completes */

Why do you need this variable? You can directly use NCT6694_URB_TIMEOUT
in the usb_bulk_msg() and friends calls.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

Dear Marc,

Thank you for reviewing,

Marc Kleine-Budde <mkl@pengutronix.de> 於 2025年2月28日 週五 下午4:52寫道：
>
> > +static int nct6694_usb_probe(struct usb_interface *iface,
> > +                          const struct usb_device_id *id)
> > +{
> > +     struct usb_device *udev = interface_to_usbdev(iface);
> > +     struct usb_endpoint_descriptor *int_endpoint;
> > +     struct usb_host_interface *interface;
> > +     struct device *dev = &iface->dev;
> > +     struct nct6694 *nct6694;
> > +     int pipe, maxp;
> > +     int ret;
> > +
> > +     nct6694 = devm_kzalloc(dev, sizeof(*nct6694), GFP_KERNEL);
> > +     if (!nct6694)
> > +             return -ENOMEM;
> > +
> > +     pipe = usb_rcvintpipe(udev, NCT6694_INT_IN_EP);
> > +     maxp = usb_maxpacket(udev, pipe);
> > +
> > +     nct6694->usb_msg = devm_kzalloc(dev, sizeof(union nct6694_usb_msg), GFP_KERNEL);
> > +     if (!nct6694->usb_msg)
> > +             return -ENOMEM;
> > +
> > +     nct6694->int_buffer = devm_kzalloc(dev, maxp, GFP_KERNEL);
> > +     if (!nct6694->int_buffer)
> > +             return -ENOMEM;
> > +
> > +     nct6694->int_in_urb = usb_alloc_urb(0, GFP_KERNEL);
> > +     if (!nct6694->int_in_urb)
> > +             return -ENOMEM;
> > +
> > +     nct6694->domain = irq_domain_add_simple(NULL, NCT6694_NR_IRQS, 0,
> > +                                             &nct6694_irq_domain_ops,
> > +                                             nct6694);
> > +     if (!nct6694->domain) {
> > +             ret = -ENODEV;
> > +             goto err_urb;
> > +     }
> > +
> > +     nct6694->dev = dev;
> > +     nct6694->udev = udev;
> > +     nct6694->timeout = NCT6694_URB_TIMEOUT; /* Wait until URB completes */
>
> Why do you need this variable? You can directly use NCT6694_URB_TIMEOUT
> in the usb_bulk_msg() and friends calls.
>

Okay, I will make the modifications in the next patch.


Best regards,
Ming