Re: [PATCH v5 1/7] mfd: Add core driver for Nuvoton NCT6694

Lee Jones
2025-01-15T16:04:09Z

On Tue, 14 Jan 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 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 | 10 +
> drivers/mfd/Makefile | 2 +
> drivers/mfd/nct6694.c | 388 ++++++++++++++++++++++++++++++++++++
> include/linux/mfd/nct6694.h | 109 ++++++++++
> 5 files changed, 516 insertions(+)
> create mode 100644 drivers/mfd/nct6694.c
> create mode 100644 include/linux/mfd/nct6694.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index a87ddad78e26..79568f82b98a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -16717,6 +16717,13 @@ 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 ae23b317a64e..3e641bfeeb38 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -1045,6 +1045,16 @@ 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 adds support for Nuvoton USB device NCT6694 sharing peripherals

Missing full stop.

> + This includes the USB device driver and core APIs.
> + Additional drivers must be enabled in order to use the functionality

New sentences do not have to be on new lines.

> + of the device.

Please explain what this functionality is.

> +
> config MFD_OCELOT
> tristate "Microsemi Ocelot External Control Support"
> depends on SPI_MASTER
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index e057d6d6faef..3c902d3704dc 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..294b6b7a902e
> --- /dev/null
> +++ b/drivers/mfd/nct6694.c
> @@ -0,0 +1,388 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Nuvoton NCT6694 MFD driver based on USB interface.

No such thing as an MFD driver. What is this device?

> + *
> + * 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>
> +
> +#define MFD_DEV_SIMPLE(_name) \
> +{ \
> + .name = NCT6694_DEV_##_name, \

Device names are usually lower case.

> +} \

MFD_CELL_NAME()

> +#define MFD_DEV_WITH_ID(_name, _id) \
> +{ \
> + .name = NCT6694_DEV_##_name, \
> + .id = _id, \
> +}

MFD_CELL_BASIC()

Or add a new one to include/linux/mfd/core.h.

> +/* MFD device resources */

This comment is superfluous.

> +static const struct mfd_cell nct6694_dev[] = {
> + MFD_DEV_WITH_ID(GPIO, 0x0),

Why doesn't PLATFORM_DEVID_AUTO work for you?

> + MFD_DEV_WITH_ID(GPIO, 0x1),
> + MFD_DEV_WITH_ID(GPIO, 0x2),
> + MFD_DEV_WITH_ID(GPIO, 0x3),
> + MFD_DEV_WITH_ID(GPIO, 0x4),
> + MFD_DEV_WITH_ID(GPIO, 0x5),
> + MFD_DEV_WITH_ID(GPIO, 0x6),
> + MFD_DEV_WITH_ID(GPIO, 0x7),
> + MFD_DEV_WITH_ID(GPIO, 0x8),
> + MFD_DEV_WITH_ID(GPIO, 0x9),
> + MFD_DEV_WITH_ID(GPIO, 0xA),
> + MFD_DEV_WITH_ID(GPIO, 0xB),
> + MFD_DEV_WITH_ID(GPIO, 0xC),
> + MFD_DEV_WITH_ID(GPIO, 0xD),
> + MFD_DEV_WITH_ID(GPIO, 0xE),
> + MFD_DEV_WITH_ID(GPIO, 0xF),
> +
> + MFD_DEV_WITH_ID(I2C, 0x0),
> + MFD_DEV_WITH_ID(I2C, 0x1),
> + MFD_DEV_WITH_ID(I2C, 0x2),
> + MFD_DEV_WITH_ID(I2C, 0x3),
> + MFD_DEV_WITH_ID(I2C, 0x4),
> + MFD_DEV_WITH_ID(I2C, 0x5),
> +
> + MFD_DEV_WITH_ID(CAN, 0x0),
> + MFD_DEV_WITH_ID(CAN, 0x1),
> +
> + MFD_DEV_WITH_ID(WDT, 0x0),
> + MFD_DEV_WITH_ID(WDT, 0x1),
> +
> + MFD_DEV_SIMPLE(HWMON),
> + MFD_DEV_SIMPLE(RTC),
> +};
> +
> +static int nct6694_response_err_handling(struct nct6694 *nct6694,
> + unsigned char err_status)
> +{
> + struct device *dev = &nct6694->udev->dev;
> +
> + switch (err_status) {
> + case NCT6694_NO_ERROR:
> + return err_status;
> + case NCT6694_NOT_SUPPORT_ERROR:
> + dev_dbg(dev, "%s: Command is not supported!\n", __func__);

These should be dev_warns().

__func__ shouldn't be used in production code.

Users don't care about functions.

> + break;
> + case NCT6694_NO_RESPONSE_ERROR:
> + dev_dbg(dev, "%s: Command received no response!\n", __func__);
> + break;
> + case NCT6694_TIMEOUT_ERROR:
> + dev_dbg(dev, "%s: Command timed out!\n", __func__);
> + break;
> + case NCT6694_PENDING:
> + dev_dbg(dev, "%s: Command is pending!\n", __func__);
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + return -EIO;
> +}
> +
> +int nct6694_read_msg(struct nct6694 *nct6694,
> + 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_dbg(&nct6694->udev->dev, "%s: Received length is not match!\n",

"does not match <something>"

> + __func__);

This should be dev_err().

> + return -EIO;
> + }
> +
> + return nct6694_response_err_handling(nct6694, msg->response_header.sts);
> +}
> +EXPORT_SYMBOL(nct6694_read_msg);
> +
> +int nct6694_write_msg(struct nct6694 *nct6694, 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_dbg(&nct6694->udev->dev, "%s: Sent length is not match!\n",
> + __func__);

This should be dev_err().

> + 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;
> + struct device *dev = &nct6694->udev->dev;
> + 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(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);

Changing a bit mask doesn't actually {en,dis}able an IRQ, right?

> +}
> +
> +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 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 = &udev->dev;
> + struct nct6694 *nct6694;
> + int pipe, maxp;
> + int ret;
> +
> + interface = iface->cur_altsetting;

Initialise this during allocation.

> + int_endpoint = &interface->endpoint[0].desc;
> + if (!usb_endpoint_is_int_in(int_endpoint))
> + return -ENODEV;
> +
> + 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);

Unwrap this - you can use up to 100-chars.

> + 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->udev = udev;
> + nct6694->timeout = NCT6694_URB_TIMEOUT; /* Wait until urb complete */

"URB completes"?

> +
> + devm_mutex_init(dev, &nct6694->access_lock);
> + devm_mutex_init(dev, &nct6694->irq_lock);
> +
> + 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;
> +
> + dev_set_drvdata(dev, nct6694);
> + usb_set_intfdata(iface, nct6694);

These two do the same thing. You don't need both.

> + 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 usb_device *udev = interface_to_usbdev(iface);
> + struct nct6694 *nct6694 = usb_get_intfdata(iface);
> +
> + mfd_remove_devices(&udev->dev);

Does devm_* work here?

> + 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-MFD driver for NCT6694");

Remove all references to MFD.

> +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..67ca835589ad
> --- /dev/null
> +++ b/include/linux/mfd/nct6694.h
> @@ -0,0 +1,109 @@
> +/* 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_DEV_GPIO "nct6694-gpio"
> +#define NCT6694_DEV_I2C "nct6694-i2c"
> +#define NCT6694_DEV_CAN "nct6694-can"
> +#define NCT6694_DEV_WDT "nct6694-wdt"
> +#define NCT6694_DEV_HWMON "nct6694-hwmon"
> +#define NCT6694_DEV_RTC "nct6694-rtc"

Use raw strings in place please.

> +#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 {

These are never used.

> + 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_CAN1,
> + NCT6694_IRQ_CAN2,
> + 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 {

Do all of these values need to be stored?

> + struct usb_device *udev;
> + struct urb *int_in_urb;
> + struct irq_domain *domain;
> + struct mutex access_lock;
> + struct mutex irq_lock;
> + 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 */

"Time" "URB"
> + long timeout;
> +};
> +
> +int nct6694_read_msg(struct nct6694 *nct6694, struct nct6694_cmd_header *cmd_hd,
> + void *buf);
> +
> +int nct6694_write_msg(struct nct6694 *nct6694, struct nct6694_cmd_header *cmd_hd,
> + void *buf);
> +
> +#endif
> --
> 2.34.1
>

--
Lee Jones [李琼斯]