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

Ming Yu
2025-01-16T02:29:05Z

Dear Lee,

Thank you for your comments,

Lee Jones <lee@kernel.org> 於 2025年1月16日 週四 上午12:04寫道：
...
> > +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.
>

Okay! I will fix these in the next patch.

> > +
> > 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?
>

Fix it in the v6.

> > + *
> > + * 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()
>

Fix it in the v6.

> > +#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.
>

Fix it in the v6.

> > +/* MFD device resources */
>
> This comment is superfluous.
>

Drop it in the v6.

> > +static const struct mfd_cell nct6694_dev[] = {
> > + MFD_DEV_WITH_ID(GPIO, 0x0),
>
> Why doesn't PLATFORM_DEVID_AUTO work for you?
>

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

> > + 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.
>

Fix it in the v6.

> > + 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>"
>

Fix it in the v6.

> > + __func__);
>
> This should be dev_err().
>

Fix it in the v6.

> > + 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().
>

Fix it in the v6.

> > + 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?
>

Yes, it's only used to record irq.

> > +}
> > +
> > +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.
>

Should these be moved before usb_fill_int_urb()?

> > + 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.
>

Fix it in the v6.

> > + 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"?
>

Fix it in the v6.

> > +
> > + 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.
>

Fix it in the v6.

> > + 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?
>

No, or do you think mfd_add_hotplug_devices() should be replaced with
devm_mfd_add_devices()?

> > + 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.
>

Fix it in the v6.

> > +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.
>

Fix it in the v6.

> > +#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.
>

Some of these numbers ared used by child devices to map the irq_domain.
(e.g. NCT6694_IRQ_CAN1, NCT6694_IRQ_RTC)

> > + 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?
>

I think that's right.

> > + 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"

Fix it in the v6.

> > + 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
> >
>

Best regards,
Ming