[PATCH v5 1/7] mfd: nct6694: Move module type macros to shared header

[PATCH v5 1/7] mfd: nct6694: Move module type macros to shared header

[a0282524688]

From: Ming Yu <a0282524688@gmail.com>

Move NCT6694_XXX_MOD  macro definitions from individual sub-device
drivers into the shared header include/linux/mfd/nct6694.h.

This is a prerequisite for supporting multiple transport interfaces
(USB, HIF) without duplicating these definitions.

No functional change.

Signed-off-by: Ming Yu <a0282524688@gmail.com>
---
Changes in v5:
- Split from the monolithic v4 patch to follow the single logical change principle.

 drivers/gpio/gpio-nct6694.c         |  7 -------
 drivers/hwmon/nct6694-hwmon.c       | 21 ---------------------
 drivers/i2c/busses/i2c-nct6694.c    |  7 -------
 drivers/net/can/usb/nct6694_canfd.c |  6 ------
 drivers/rtc/rtc-nct6694.c           |  7 -------
 drivers/watchdog/nct6694_wdt.c      |  7 -------
 include/linux/mfd/nct6694.h         |  9 +++++++++
 7 files changed, 9 insertions(+), 55 deletions(-)

diff --git a/drivers/gpio/gpio-nct6694.c b/drivers/gpio/gpio-nct6694.c
index a8607f0d9915..53bfc5983648 100644
--- a/drivers/gpio/gpio-nct6694.c
+++ b/drivers/gpio/gpio-nct6694.c
@@ -13,13 +13,6 @@
 #include <linux/module.h>
 #include <linux/platform_device.h>
 
-/*
- * USB command module type for NCT6694 GPIO controller.
- * This defines the module type used for communication with the NCT6694
- * GPIO controller over the USB interface.
- */
-#define NCT6694_GPIO_MOD	0xFF
-
 #define NCT6694_GPIO_VER	0x90
 #define NCT6694_GPIO_VALID	0x110
 #define NCT6694_GPI_DATA	0x120
diff --git a/drivers/hwmon/nct6694-hwmon.c b/drivers/hwmon/nct6694-hwmon.c
index 6dcf22ca5018..581451875f2c 100644
--- a/drivers/hwmon/nct6694-hwmon.c
+++ b/drivers/hwmon/nct6694-hwmon.c
@@ -15,13 +15,6 @@
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 
-/*
- * USB command module type for NCT6694 report channel
- * This defines the module type used for communication with the NCT6694
- * report channel over the USB interface.
- */
-#define NCT6694_RPT_MOD			0xFF
-
 /* Report channel */
 /*
  * The report channel is used to report the status of the hardware monitor
@@ -38,13 +31,6 @@
 #define NCT6694_TIN_STS(x)		(0x6A + (x))
 #define NCT6694_FIN_STS(x)		(0x6E + (x))
 
-/*
- * USB command module type for NCT6694 HWMON controller.
- * This defines the module type used for communication with the NCT6694
- * HWMON controller over the USB interface.
- */
-#define NCT6694_HWMON_MOD		0x00
-
 /* Command 00h - Hardware Monitor Control */
 #define NCT6694_HWMON_CONTROL		0x00
 #define NCT6694_HWMON_CONTROL_SEL	0x00
@@ -53,13 +39,6 @@
 #define NCT6694_HWMON_ALARM		0x02
 #define NCT6694_HWMON_ALARM_SEL		0x00
 
-/*
- * USB command module type for NCT6694 PWM controller.
- * This defines the module type used for communication with the NCT6694
- * PWM controller over the USB interface.
- */
-#define NCT6694_PWM_MOD			0x01
-
 /* PWM Command - Manual Control */
 #define NCT6694_PWM_CONTROL		0x01
 #define NCT6694_PWM_CONTROL_SEL		0x00
diff --git a/drivers/i2c/busses/i2c-nct6694.c b/drivers/i2c/busses/i2c-nct6694.c
index 1413ab6f9462..ef3329f34246 100644
--- a/drivers/i2c/busses/i2c-nct6694.c
+++ b/drivers/i2c/busses/i2c-nct6694.c
@@ -12,13 +12,6 @@
 #include <linux/module.h>
 #include <linux/platform_device.h>
 
-/*
- * USB command module type for NCT6694 I2C controller.
- * This defines the module type used for communication with the NCT6694
- * I2C controller over the USB interface.
- */
-#define NCT6694_I2C_MOD			0x03
-
 /* Command 00h - I2C Deliver */
 #define NCT6694_I2C_DELIVER		0x00
 #define NCT6694_I2C_DELIVER_SEL		0x00
diff --git a/drivers/net/can/usb/nct6694_canfd.c b/drivers/net/can/usb/nct6694_canfd.c
index e5f7f8849a73..262b4c26c9d4 100644
--- a/drivers/net/can/usb/nct6694_canfd.c
+++ b/drivers/net/can/usb/nct6694_canfd.c
@@ -18,12 +18,6 @@
 
 #define DEVICE_NAME "nct6694-canfd"
 
-/* USB command module type for NCT6694 CANfd controller.
- * This defines the module type used for communication with the NCT6694
- * CANfd controller over the USB interface.
- */
-#define NCT6694_CANFD_MOD			0x05
-
 /* Command 00h - CAN Setting and Initialization */
 #define NCT6694_CANFD_SETTING			0x00
 #define NCT6694_CANFD_SETTING_ACTIVE_CTRL1	BIT(0)
diff --git a/drivers/rtc/rtc-nct6694.c b/drivers/rtc/rtc-nct6694.c
index 35401a0d9cf5..c06902f150c9 100644
--- a/drivers/rtc/rtc-nct6694.c
+++ b/drivers/rtc/rtc-nct6694.c
@@ -14,13 +14,6 @@
 #include <linux/rtc.h>
 #include <linux/slab.h>
 
-/*
- * USB command module type for NCT6694 RTC controller.
- * This defines the module type used for communication with the NCT6694
- * RTC controller over the USB interface.
- */
-#define NCT6694_RTC_MOD		0x08
-
 /* Command 00h - RTC Time */
 #define NCT6694_RTC_TIME	0x0000
 #define NCT6694_RTC_TIME_SEL	0x00
diff --git a/drivers/watchdog/nct6694_wdt.c b/drivers/watchdog/nct6694_wdt.c
index bc3689bd4b6b..4c06ac105562 100644
--- a/drivers/watchdog/nct6694_wdt.c
+++ b/drivers/watchdog/nct6694_wdt.c
@@ -20,13 +20,6 @@
 
 #define NCT6694_WDT_MAX_DEVS		2
 
-/*
- * USB command module type for NCT6694 WDT controller.
- * This defines the module type used for communication with the NCT6694
- * WDT controller over the USB interface.
- */
-#define NCT6694_WDT_MOD			0x07
-
 /* Command 00h - WDT Setup */
 #define NCT6694_WDT_SETUP		0x00
 #define NCT6694_WDT_SETUP_SEL(idx)	(idx ? 0x01 : 0x00)
diff --git a/include/linux/mfd/nct6694.h b/include/linux/mfd/nct6694.h
index 6eb9be2cd4a0..3c683e317aa3 100644
--- a/include/linux/mfd/nct6694.h
+++ b/include/linux/mfd/nct6694.h
@@ -8,6 +8,15 @@
 #ifndef __MFD_NCT6694_H
 #define __MFD_NCT6694_H
 
+#define NCT6694_HWMON_MOD	0x00
+#define NCT6694_PWM_MOD		0x01
+#define NCT6694_I2C_MOD		0x03
+#define NCT6694_CANFD_MOD	0x05
+#define NCT6694_WDT_MOD		0x07
+#define NCT6694_RTC_MOD		0x08
+#define NCT6694_RPT_MOD		0xFF
+#define NCT6694_GPIO_MOD	NCT6694_RPT_MOD
+
 #define NCT6694_VENDOR_ID	0x0416
 #define NCT6694_PRODUCT_ID	0x200B
 #define NCT6694_INT_IN_EP	0x81
-- 
2.34.1

Re: [PATCH v5 1/7] mfd: nct6694: Move module type macros to shared header

[sashiko-bot]

> From: Ming Yu <a0282524688@gmail.com>
> 
> Move NCT6694_XXX_MOD  macro definitions from individual sub-device
> drivers into the shared header include/linux/mfd/nct6694.h.
> 
> This is a prerequisite for supporting multiple transport interfaces
> (USB, HIF) without duplicating these definitions.
> 
> No functional change.
> 
> Signed-off-by: Ming Yu <a0282524688@gmail.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260525081736.2904310-1-a0282524688@gmail.com?part=1

[PATCH v5 2/7] mfd: nct6694: Refactor USB-specific data into nct6694_usb_data

[a0282524688]

From: Ming Yu <a0282524688@gmail.com>

Separate USB transport-specific fields from the core nct6694 structure
into a new nct6694_usb_data structure. This decouples the shared MFD
core from the USB transport layer, preparing the driver for potential
support of alternative transport backends in the future.

The following fields are moved into nct6694_usb_data:
  - access_lock
  - int_in_urb
  - udev
  - usb_msg
  - int_buffer

The core nct6694 structure now holds a void *priv pointer to reference
the transport-specific data. USB-only definitions (vendor/product IDs,
endpoint addresses, URB timeout, and the USB message union) are also
moved from the shared header into the USB driver source file.

Signed-off-by: Ming Yu <a0282524688@gmail.com>
---
Changes in v5:
- Split from the monolithic v4 patch to follow the single logical change principle.

 drivers/mfd/nct6694.c       | 76 ++++++++++++++++++++++++++-----------
 include/linux/mfd/nct6694.h | 27 ++++---------
 2 files changed, 62 insertions(+), 41 deletions(-)

diff --git a/drivers/mfd/nct6694.c b/drivers/mfd/nct6694.c
index 308b2fda3055..58c1cbcbe3f2 100644
--- a/drivers/mfd/nct6694.c
+++ b/drivers/mfd/nct6694.c
@@ -10,8 +10,8 @@
  */
 
 #include <linux/bits.h>
-#include <linux/interrupt.h>
 #include <linux/idr.h>
+#include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/irqdomain.h>
 #include <linux/kernel.h>
@@ -22,6 +22,27 @@
 #include <linux/spinlock.h>
 #include <linux/usb.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_URB_TIMEOUT	1000
+
+union __packed nct6694_usb_msg {
+	struct nct6694_cmd_header cmd_header;
+	struct nct6694_response_header response_header;
+};
+
+struct nct6694_usb_data {
+	struct mutex access_lock;
+	struct urb *int_in_urb;
+	struct usb_device *udev;
+	union nct6694_usb_msg *usb_msg;
+	__le32 *int_buffer;
+};
+
 static const struct mfd_cell nct6694_devs[] = {
 	MFD_CELL_NAME("nct6694-gpio"),
 	MFD_CELL_NAME("nct6694-gpio"),
@@ -96,11 +117,12 @@ static int nct6694_response_err_handling(struct nct6694 *nct6694, unsigned char
  */
 int nct6694_read_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf)
 {
-	union nct6694_usb_msg *msg = nct6694->usb_msg;
-	struct usb_device *udev = nct6694->udev;
+	struct nct6694_usb_data *udata = nct6694->priv;
+	union nct6694_usb_msg *msg = udata->usb_msg;
+	struct usb_device *udev = udata->udev;
 	int tx_len, rx_len, ret;
 
-	guard(mutex)(&nct6694->access_lock);
+	guard(mutex)(&udata->access_lock);
 
 	memcpy(&msg->cmd_header, cmd_hd, sizeof(*cmd_hd));
 	msg->cmd_header.hctrl = NCT6694_HCTRL_GET;
@@ -146,11 +168,12 @@ EXPORT_SYMBOL_GPL(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;
-	struct usb_device *udev = nct6694->udev;
+	struct nct6694_usb_data *udata = nct6694->priv;
+	union nct6694_usb_msg *msg = udata->usb_msg;
+	struct usb_device *udev = udata->udev;
 	int tx_len, rx_len, ret;
 
-	guard(mutex)(&nct6694->access_lock);
+	guard(mutex)(&udata->access_lock);
 
 	memcpy(&msg->cmd_header, cmd_hd, sizeof(*cmd_hd));
 	msg->cmd_header.hctrl = NCT6694_HCTRL_SET;
@@ -277,6 +300,7 @@ static int nct6694_usb_probe(struct usb_interface *iface,
 	struct usb_endpoint_descriptor *int_endpoint;
 	struct usb_host_interface *interface;
 	struct device *dev = &iface->dev;
+	struct nct6694_usb_data *udata;
 	struct nct6694 *nct6694;
 	int ret;
 
@@ -284,18 +308,26 @@ static int nct6694_usb_probe(struct usb_interface *iface,
 	if (!nct6694)
 		return -ENOMEM;
 
-	nct6694->usb_msg = devm_kzalloc(dev, sizeof(union nct6694_usb_msg), GFP_KERNEL);
-	if (!nct6694->usb_msg)
+	udata = devm_kzalloc(dev, sizeof(*udata), GFP_KERNEL);
+	if (!udata)
+		return -ENOMEM;
+
+	udata->usb_msg = devm_kzalloc(dev, sizeof(*udata->usb_msg), GFP_KERNEL);
+	if (!udata->usb_msg)
 		return -ENOMEM;
 
-	nct6694->int_buffer = devm_kzalloc(dev, sizeof(*nct6694->int_buffer), GFP_KERNEL);
-	if (!nct6694->int_buffer)
+	udata->int_buffer = devm_kzalloc(dev, sizeof(*udata->int_buffer), GFP_KERNEL);
+	if (!udata->int_buffer)
 		return -ENOMEM;
 
-	nct6694->int_in_urb = usb_alloc_urb(0, GFP_KERNEL);
-	if (!nct6694->int_in_urb)
+	udata->int_in_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!udata->int_in_urb)
 		return -ENOMEM;
 
+	udata->udev = udev;
+
+	nct6694->priv = udata;
+
 	nct6694->domain = irq_domain_create_simple(NULL, NCT6694_NR_IRQS, 0,
 						   &nct6694_irq_domain_ops,
 						   nct6694);
@@ -305,7 +337,6 @@ static int nct6694_usb_probe(struct usb_interface *iface,
 	}
 
 	nct6694->dev = dev;
-	nct6694->udev = udev;
 
 	ida_init(&nct6694->gpio_ida);
 	ida_init(&nct6694->i2c_ida);
@@ -314,7 +345,7 @@ static int nct6694_usb_probe(struct usb_interface *iface,
 
 	spin_lock_init(&nct6694->irq_lock);
 
-	ret = devm_mutex_init(dev, &nct6694->access_lock);
+	ret = devm_mutex_init(dev, &udata->access_lock);
 	if (ret)
 		goto err_ida;
 
@@ -326,11 +357,11 @@ static int nct6694_usb_probe(struct usb_interface *iface,
 		goto err_ida;
 	}
 
-	usb_fill_int_urb(nct6694->int_in_urb, udev, usb_rcvintpipe(udev, NCT6694_INT_IN_EP),
-			 nct6694->int_buffer, sizeof(*nct6694->int_buffer), usb_int_callback,
+	usb_fill_int_urb(udata->int_in_urb, udev, usb_rcvintpipe(udev, NCT6694_INT_IN_EP),
+			 udata->int_buffer, sizeof(*udata->int_buffer), usb_int_callback,
 			 nct6694, int_endpoint->bInterval);
 
-	ret = usb_submit_urb(nct6694->int_in_urb, GFP_KERNEL);
+	ret = usb_submit_urb(udata->int_in_urb, GFP_KERNEL);
 	if (ret)
 		goto err_ida;
 
@@ -343,7 +374,7 @@ static int nct6694_usb_probe(struct usb_interface *iface,
 	return 0;
 
 err_mfd:
-	usb_kill_urb(nct6694->int_in_urb);
+	usb_kill_urb(udata->int_in_urb);
 err_ida:
 	ida_destroy(&nct6694->wdt_ida);
 	ida_destroy(&nct6694->canfd_ida);
@@ -351,22 +382,23 @@ static int nct6694_usb_probe(struct usb_interface *iface,
 	ida_destroy(&nct6694->gpio_ida);
 	irq_domain_remove(nct6694->domain);
 err_urb:
-	usb_free_urb(nct6694->int_in_urb);
+	usb_free_urb(udata->int_in_urb);
 	return ret;
 }
 
 static void nct6694_usb_disconnect(struct usb_interface *iface)
 {
 	struct nct6694 *nct6694 = usb_get_intfdata(iface);
+	struct nct6694_usb_data *udata = nct6694->priv;
 
 	mfd_remove_devices(nct6694->dev);
-	usb_kill_urb(nct6694->int_in_urb);
+	usb_kill_urb(udata->int_in_urb);
 	ida_destroy(&nct6694->wdt_ida);
 	ida_destroy(&nct6694->canfd_ida);
 	ida_destroy(&nct6694->i2c_ida);
 	ida_destroy(&nct6694->gpio_ida);
 	irq_domain_remove(nct6694->domain);
-	usb_free_urb(nct6694->int_in_urb);
+	usb_free_urb(udata->int_in_urb);
 }
 
 static const struct usb_device_id nct6694_ids[] = {
diff --git a/include/linux/mfd/nct6694.h b/include/linux/mfd/nct6694.h
index 3c683e317aa3..3f5dd53f38de 100644
--- a/include/linux/mfd/nct6694.h
+++ b/include/linux/mfd/nct6694.h
@@ -2,12 +2,18 @@
 /*
  * Copyright (C) 2025 Nuvoton Technology Corp.
  *
- * Nuvoton NCT6694 USB transaction and data structure.
+ * Nuvoton NCT6694 core definitions shared by all transport drivers
+ * and sub-device drivers.
  */
 
 #ifndef __MFD_NCT6694_H
 #define __MFD_NCT6694_H
 
+#include <linux/idr.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
 #define NCT6694_HWMON_MOD	0x00
 #define NCT6694_PWM_MOD		0x01
 #define NCT6694_I2C_MOD		0x03
@@ -17,17 +23,9 @@
 #define NCT6694_RPT_MOD		0xFF
 #define NCT6694_GPIO_MOD	NCT6694_RPT_MOD
 
-#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,
@@ -84,11 +82,6 @@ struct __packed nct6694_response_header {
 	__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 ida gpio_ida;
@@ -96,13 +89,9 @@ struct nct6694 {
 	struct ida canfd_ida;
 	struct ida wdt_ida;
 	struct irq_domain *domain;
-	struct mutex access_lock;
 	spinlock_t irq_lock;
-	struct urb *int_in_urb;
-	struct usb_device *udev;
-	union nct6694_usb_msg *usb_msg;
-	__le32 *int_buffer;
 	unsigned int irq_enable;
+	void *priv;
 };
 
 int nct6694_read_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf);
-- 
2.34.1

[PATCH v5 3/7] mfd: nct6694: Introduce transport abstraction with function pointers

[a0282524688]

From: Ming Yu <a0282524688@gmail.com>

Add `read_msg` and `write_msg` function pointers to `struct nct6694`
and provide static inline helpers for sub-devices. The USB-specific
I/O functions are made static and assigned during probe.

This decouples sub-device drivers from the underlying USB implementation,
paving the way for alternative transport interfaces (e.g., HIF) in the
future without modifying client drivers.

Signed-off-by: Ming Yu <a0282524688@gmail.com>
---
Changes in v5:
- Split from the monolithic v4 patch to follow the single logical change principle.

 drivers/mfd/nct6694.c       | 12 ++++++++----
 include/linux/mfd/nct6694.h | 22 ++++++++++++++++++++--
 2 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/drivers/mfd/nct6694.c b/drivers/mfd/nct6694.c
index 58c1cbcbe3f2..b88863a0b70f 100644
--- a/drivers/mfd/nct6694.c
+++ b/drivers/mfd/nct6694.c
@@ -115,7 +115,9 @@ static int nct6694_response_err_handling(struct nct6694 *nct6694, unsigned char
  *
  * Return: Negative value on error or 0 on success.
  */
-int nct6694_read_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf)
+static int nct6694_read_msg(struct nct6694 *nct6694,
+			    const struct nct6694_cmd_header *cmd_hd,
+			    void *buf)
 {
 	struct nct6694_usb_data *udata = nct6694->priv;
 	union nct6694_usb_msg *msg = udata->usb_msg;
@@ -153,7 +155,6 @@ int nct6694_read_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *c
 
 	return nct6694_response_err_handling(nct6694, msg->response_header.sts);
 }
-EXPORT_SYMBOL_GPL(nct6694_read_msg);
 
 /**
  * nct6694_write_msg() - Write message to NCT6694 device
@@ -166,7 +167,9 @@ EXPORT_SYMBOL_GPL(nct6694_read_msg);
  *
  * Return: Negative value on error or 0 on success.
  */
-int nct6694_write_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf)
+static int nct6694_write_msg(struct nct6694 *nct6694,
+			     const struct nct6694_cmd_header *cmd_hd,
+			     void *buf)
 {
 	struct nct6694_usb_data *udata = nct6694->priv;
 	union nct6694_usb_msg *msg = udata->usb_msg;
@@ -210,7 +213,6 @@ int nct6694_write_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *
 
 	return nct6694_response_err_handling(nct6694, msg->response_header.sts);
 }
-EXPORT_SYMBOL_GPL(nct6694_write_msg);
 
 static void usb_int_callback(struct urb *urb)
 {
@@ -327,6 +329,8 @@ static int nct6694_usb_probe(struct usb_interface *iface,
 	udata->udev = udev;
 
 	nct6694->priv = udata;
+	nct6694->read_msg = nct6694_read_msg;
+	nct6694->write_msg = nct6694_write_msg;
 
 	nct6694->domain = irq_domain_create_simple(NULL, NCT6694_NR_IRQS, 0,
 						   &nct6694_irq_domain_ops,
diff --git a/include/linux/mfd/nct6694.h b/include/linux/mfd/nct6694.h
index 3f5dd53f38de..3079c74110aa 100644
--- a/include/linux/mfd/nct6694.h
+++ b/include/linux/mfd/nct6694.h
@@ -92,9 +92,27 @@ struct nct6694 {
 	spinlock_t irq_lock;
 	unsigned int irq_enable;
 	void *priv;
+
+	int (*read_msg)(struct nct6694 *nct6694,
+			const struct nct6694_cmd_header *cmd_hd,
+			void *buf);
+	int (*write_msg)(struct nct6694 *nct6694,
+			 const struct nct6694_cmd_header *cmd_hd,
+			 void *buf);
 };
 
-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);
+static inline int nct6694_read_msg(struct nct6694 *nct6694,
+				   const struct nct6694_cmd_header *cmd_hd,
+				   void *buf)
+{
+	return nct6694->read_msg(nct6694, cmd_hd, buf);
+}
+
+static inline int nct6694_write_msg(struct nct6694 *nct6694,
+				    const struct nct6694_cmd_header *cmd_hd,
+				    void *buf)
+{
+	return nct6694->write_msg(nct6694, cmd_hd, buf);
+}
 
 #endif
-- 
2.34.1

Re: [PATCH v5 3/7] mfd: nct6694: Introduce transport abstraction with function pointers

[Lee Jones]

On Mon, 25 May 2026, a0282524688@gmail.com wrote:

> From: Ming Yu <a0282524688@gmail.com>
> 
> Add `read_msg` and `write_msg` function pointers to `struct nct6694`
> and provide static inline helpers for sub-devices. The USB-specific
> I/O functions are made static and assigned during probe.
> 
> This decouples sub-device drivers from the underlying USB implementation,
> paving the way for alternative transport interfaces (e.g., HIF) in the
> future without modifying client drivers.
> 
> Signed-off-by: Ming Yu <a0282524688@gmail.com>
> ---
> Changes in v5:
> - Split from the monolithic v4 patch to follow the single logical change principle.
> 
>  drivers/mfd/nct6694.c       | 12 ++++++++----
>  include/linux/mfd/nct6694.h | 22 ++++++++++++++++++++--
>  2 files changed, 28 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mfd/nct6694.c b/drivers/mfd/nct6694.c
> index 58c1cbcbe3f2..b88863a0b70f 100644
> --- a/drivers/mfd/nct6694.c
> +++ b/drivers/mfd/nct6694.c
> @@ -115,7 +115,9 @@ static int nct6694_response_err_handling(struct nct6694 *nct6694, unsigned char
>   *
>   * Return: Negative value on error or 0 on success.
>   */
> -int nct6694_read_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf)
> +static int nct6694_read_msg(struct nct6694 *nct6694,
> +			    const struct nct6694_cmd_header *cmd_hd,
> +			    void *buf)
>  {
>  	struct nct6694_usb_data *udata = nct6694->priv;
>  	union nct6694_usb_msg *msg = udata->usb_msg;
> @@ -153,7 +155,6 @@ int nct6694_read_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *c
>  
>  	return nct6694_response_err_handling(nct6694, msg->response_header.sts);
>  }
> -EXPORT_SYMBOL_GPL(nct6694_read_msg);
>  
>  /**
>   * nct6694_write_msg() - Write message to NCT6694 device
> @@ -166,7 +167,9 @@ EXPORT_SYMBOL_GPL(nct6694_read_msg);
>   *
>   * Return: Negative value on error or 0 on success.
>   */
> -int nct6694_write_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *cmd_hd, void *buf)
> +static int nct6694_write_msg(struct nct6694 *nct6694,
> +			     const struct nct6694_cmd_header *cmd_hd,
> +			     void *buf)
>  {
>  	struct nct6694_usb_data *udata = nct6694->priv;
>  	union nct6694_usb_msg *msg = udata->usb_msg;
> @@ -210,7 +213,6 @@ int nct6694_write_msg(struct nct6694 *nct6694, const struct nct6694_cmd_header *
>  
>  	return nct6694_response_err_handling(nct6694, msg->response_header.sts);
>  }
> -EXPORT_SYMBOL_GPL(nct6694_write_msg);
>  
>  static void usb_int_callback(struct urb *urb)
>  {
> @@ -327,6 +329,8 @@ static int nct6694_usb_probe(struct usb_interface *iface,
>  	udata->udev = udev;
>  
>  	nct6694->priv = udata;
> +	nct6694->read_msg = nct6694_read_msg;
> +	nct6694->write_msg = nct6694_write_msg;
>  
>  	nct6694->domain = irq_domain_create_simple(NULL, NCT6694_NR_IRQS, 0,
>  						   &nct6694_irq_domain_ops,
> diff --git a/include/linux/mfd/nct6694.h b/include/linux/mfd/nct6694.h
> index 3f5dd53f38de..3079c74110aa 100644
> --- a/include/linux/mfd/nct6694.h
> +++ b/include/linux/mfd/nct6694.h
> @@ -92,9 +92,27 @@ struct nct6694 {
>  	spinlock_t irq_lock;
>  	unsigned int irq_enable;
>  	void *priv;
> +
> +	int (*read_msg)(struct nct6694 *nct6694,
> +			const struct nct6694_cmd_header *cmd_hd,
> +			void *buf);
> +	int (*write_msg)(struct nct6694 *nct6694,
> +			 const struct nct6694_cmd_header *cmd_hd,
> +			 void *buf);
>  };
>  
> -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);
> +static inline int nct6694_read_msg(struct nct6694 *nct6694,
> +				   const struct nct6694_cmd_header *cmd_hd,
> +				   void *buf)
> +{
> +	return nct6694->read_msg(nct6694, cmd_hd, buf);
> +}
> +
> +static inline int nct6694_write_msg(struct nct6694 *nct6694,
> +				    const struct nct6694_cmd_header *cmd_hd,
> +				    void *buf)
> +{
> +	return nct6694->write_msg(nct6694, cmd_hd, buf);
> +}

I very much dislike pointers to functions and abstraction for the sake
of abstraction, at least at the driver-level.

Can you find another way to solve this problem please?


-- 
Lee Jones

Re: [PATCH v5 3/7] mfd: nct6694: Introduce transport abstraction with function pointers

[Ming Yu]

Dear Lee,

Thanks for the review.

Lee Jones <lee@kernel.org> 於 2026年6月5日週五 上午12:25寫道：
>
> > @@ -92,9 +92,27 @@ struct nct6694 {
> >       spinlock_t irq_lock;
> >       unsigned int irq_enable;
> >       void *priv;
> > +
> > +     int (*read_msg)(struct nct6694 *nct6694,
> > +                     const struct nct6694_cmd_header *cmd_hd,
> > +                     void *buf);
> > +     int (*write_msg)(struct nct6694 *nct6694,
> > +                      const struct nct6694_cmd_header *cmd_hd,
> > +                      void *buf);
> >  };
> >
> > -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);
> > +static inline int nct6694_read_msg(struct nct6694 *nct6694,
> > +                                const struct nct6694_cmd_header *cmd_hd,
> > +                                void *buf)
> > +{
> > +     return nct6694->read_msg(nct6694, cmd_hd, buf);
> > +}
> > +
> > +static inline int nct6694_write_msg(struct nct6694 *nct6694,
> > +                                 const struct nct6694_cmd_header *cmd_hd,
> > +                                 void *buf)
> > +{
> > +     return nct6694->write_msg(nct6694, cmd_hd, buf);
> > +}
>
> I very much dislike pointers to functions and abstraction for the sake
> of abstraction, at least at the driver-level.
>
> Can you find another way to solve this problem please?
>

The reason for the abstraction is that patch 7/7 introduces a second
transport (HIF/eSPI), and the sub-device drivers need a way to perform
I/O without being coupled to a specific transport.

I'd like to rework this -- could you let me know which approach you'd prefer?

Keep nct6694_read_msg()/nct6694_write_msg() as exported functions in
nct6694-core.c, with the core dispatching to the appropriate
transport-specific implementation based on an internal transport type
indicator.

Use a const struct nct6694_transport_ops *ops in struct nct6694,
following the pattern used by subsystems like regmap_bus and
spi_controller_mem_ops.

Happy to go with whichever direction you think is cleaner.


Thanks,
Ming

[PATCH v5 4/7] mfd: nct6694: Rename static I/O functions with _usb_ prefix

[a0282524688]

From: Ming Yu <a0282524688@gmail.com>

Rename the static I/O and error handling routines to include an
`_usb_` prefix (e.g., nct6694_usb_read_msg, nct6694_usb_err_handling).

This clearly identifies these functions as specific to the USB
transport implementation. It improves code readability and avoids
naming confusion with the core API abstracted in the shared header,
preparing the codebase for future alternative transport drivers.

Signed-off-by: Ming Yu <a0282524688@gmail.com>
---
Changes in v5:
- Split from the monolithic v4 patch to follow the single logical change principle.

 drivers/mfd/nct6694.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/mfd/nct6694.c b/drivers/mfd/nct6694.c
index b88863a0b70f..289580bbc472 100644
--- a/drivers/mfd/nct6694.c
+++ b/drivers/mfd/nct6694.c
@@ -79,7 +79,7 @@ static const struct mfd_cell nct6694_devs[] = {
 	MFD_CELL_NAME("nct6694-rtc"),
 };
 
-static int nct6694_response_err_handling(struct nct6694 *nct6694, unsigned char err_status)
+static int nct6694_usb_err_handling(struct nct6694 *nct6694, unsigned char err_status)
 {
 	switch (err_status) {
 	case NCT6694_NO_ERROR:
@@ -104,7 +104,7 @@ static int nct6694_response_err_handling(struct nct6694 *nct6694, unsigned char
 }
 
 /**
- * nct6694_read_msg() - Read message from NCT6694 device
+ * nct6694_usb_read_msg() - Read message from NCT6694 device via USB
  * @nct6694: NCT6694 device pointer
  * @cmd_hd: command header structure
  * @buf: buffer to store the response data
@@ -115,9 +115,9 @@ static int nct6694_response_err_handling(struct nct6694 *nct6694, unsigned char
  *
  * Return: Negative value on error or 0 on success.
  */
-static int nct6694_read_msg(struct nct6694 *nct6694,
-			    const struct nct6694_cmd_header *cmd_hd,
-			    void *buf)
+static int nct6694_usb_read_msg(struct nct6694 *nct6694,
+				const struct nct6694_cmd_header *cmd_hd,
+				void *buf)
 {
 	struct nct6694_usb_data *udata = nct6694->priv;
 	union nct6694_usb_msg *msg = udata->usb_msg;
@@ -153,11 +153,11 @@ static int nct6694_read_msg(struct nct6694 *nct6694,
 		return -EIO;
 	}
 
-	return nct6694_response_err_handling(nct6694, msg->response_header.sts);
+	return nct6694_usb_err_handling(nct6694, msg->response_header.sts);
 }
 
 /**
- * nct6694_write_msg() - Write message to NCT6694 device
+ * nct6694_usb_write_msg() - Write message to NCT6694 device via USB
  * @nct6694: NCT6694 device pointer
  * @cmd_hd: command header structure
  * @buf: buffer containing the data to be sent
@@ -167,9 +167,9 @@ static int nct6694_read_msg(struct nct6694 *nct6694,
  *
  * Return: Negative value on error or 0 on success.
  */
-static int nct6694_write_msg(struct nct6694 *nct6694,
-			     const struct nct6694_cmd_header *cmd_hd,
-			     void *buf)
+static int nct6694_usb_write_msg(struct nct6694 *nct6694,
+				 const struct nct6694_cmd_header *cmd_hd,
+				 void *buf)
 {
 	struct nct6694_usb_data *udata = nct6694->priv;
 	union nct6694_usb_msg *msg = udata->usb_msg;
@@ -211,7 +211,7 @@ static int nct6694_write_msg(struct nct6694 *nct6694,
 		return -EIO;
 	}
 
-	return nct6694_response_err_handling(nct6694, msg->response_header.sts);
+	return nct6694_usb_err_handling(nct6694, msg->response_header.sts);
 }
 
 static void usb_int_callback(struct urb *urb)
@@ -329,8 +329,8 @@ static int nct6694_usb_probe(struct usb_interface *iface,
 	udata->udev = udev;
 
 	nct6694->priv = udata;
-	nct6694->read_msg = nct6694_read_msg;
-	nct6694->write_msg = nct6694_write_msg;
+	nct6694->read_msg = nct6694_usb_read_msg;
+	nct6694->write_msg = nct6694_usb_write_msg;
 
 	nct6694->domain = irq_domain_create_simple(NULL, NCT6694_NR_IRQS, 0,
 						   &nct6694_irq_domain_ops,
-- 
2.34.1

[PATCH v5 5/7] mfd: nct6694: Rename driver to nct6694-usb and update Kconfig

[a0282524688]

From: Ming Yu <a0282524688@gmail.com>

Rename nct6694.c to nct6694-usb.c to accurately reflect that it
implements the USB transport backend.

Additionally, introduce a new MFD_NCT6694_USB Kconfig option and convert
the existing MFD_NCT6694 into a hidden core symbol. The core symbol is
now automatically selected by the transport drivers.

This Kconfig and naming restructure aligns with standard MFD transport
abstraction practices, paving the way for future interfaces (e.g., HIF)
to be seamlessly integrated.

Signed-off-by: Ming Yu <a0282524688@gmail.com>
---
Changes in v5:
- Split from the monolithic v4 patch to follow the single logical change principle.

 MAINTAINERS                              |  2 +-
 drivers/mfd/Kconfig                      | 22 +++++++++++++++++++++-
 drivers/mfd/Makefile                     |  2 +-
 drivers/mfd/{nct6694.c => nct6694-usb.c} |  0
 4 files changed, 23 insertions(+), 3 deletions(-)
 rename drivers/mfd/{nct6694.c => nct6694-usb.c} (100%)

diff --git a/MAINTAINERS b/MAINTAINERS
index 8d173418d483..d52a3028e7c0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19098,7 +19098,7 @@ S:	Supported
 F:	drivers/gpio/gpio-nct6694.c
 F:	drivers/hwmon/nct6694-hwmon.c
 F:	drivers/i2c/busses/i2c-nct6694.c
-F:	drivers/mfd/nct6694.c
+F:	drivers/mfd/nct6694-usb.c
 F:	drivers/net/can/usb/nct6694_canfd.c
 F:	drivers/rtc/rtc-nct6694.c
 F:	drivers/watchdog/nct6694_wdt.c
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 7192c9d1d268..b5b30371da59 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1164,8 +1164,19 @@ config MFD_MENF21BMC
 	  will be called menf21bmc.
 
 config MFD_NCT6694
-	tristate "Nuvoton NCT6694 support"
+	tristate
 	select MFD_CORE
+	help
+	  Core MFD support for the Nuvoton NCT6694 peripheral expander.
+	  This provides the common APIs and shared structures used by all
+	  interfaces (USB, HIF) to access the NCT6694 hardware features
+	  such as GPIO, I2C, CAN-FD, Watchdog, ADC, PWM, and RTC.
+
+	  It is selected automatically by the transport interface drivers.
+
+config MFD_NCT6694_USB
+	tristate "Nuvoton NCT6694 USB interface support"
+	select MFD_NCT6694
 	depends on USB
 	help
 	  This enables support for the Nuvoton USB device NCT6694, which shares
@@ -1177,6 +1188,15 @@ config MFD_NCT6694
 	  monitoring and control features.
 	  Additional drivers must be enabled to utilize the specific
 	  functionalities of the device.
+	  This enables support for the Nuvoton NCT6694 peripheral expander
+	  connected via the USB interface.
+
+	  The transport driver uses USB bulk and interrupt transfers to
+	  communicate with the NCT6694 firmware. Enable this option if you
+	  are using the NCT6694 via a USB connection.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called nct6694.
 
 config MFD_OCELOT
 	tristate "Microsemi Ocelot External Control Support"
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index e75e8045c28a..361c5360e656 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -124,7 +124,7 @@ obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
 
 obj-$(CONFIG_MFD_PF1550)	+= pf1550.o
 
-obj-$(CONFIG_MFD_NCT6694)	+= nct6694.o
+obj-$(CONFIG_MFD_NCT6694_USB)	+= nct6694-usb.o
 
 obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
 
diff --git a/drivers/mfd/nct6694.c b/drivers/mfd/nct6694-usb.c
similarity index 100%
rename from drivers/mfd/nct6694.c
rename to drivers/mfd/nct6694-usb.c
-- 
2.34.1

[PATCH v5 6/7] mfd: nct6694: Extract core device management into a separate module

[a0282524688]

From: Ming Yu <a0282524688@gmail.com>

Extract the transport-agnostic core logic, including IRQ domain setup,
IDA initialization, and MFD sub-device registration, from the USB driver
into a new nct6694-core.c module.

The core routines are exported as nct6694_core_probe() and
nct6694_core_remove() to be consumed by the transport drivers. The USB
driver is updated to pass its specific MFD cells to the core probe
routine.

This completes the transport abstraction, ensuring that the shared
device management logic is cleanly separated from the underlying I/O
implementation, and is fully ready for new transport backends
(e.g., HIF).

Signed-off-by: Ming Yu <a0282524688@gmail.com>
---
Changes in v5:
- Split from the monolithic v4 patch to follow the single logical change principle.

 MAINTAINERS                 |   2 +-
 drivers/mfd/Makefile        |   1 +
 drivers/mfd/nct6694-core.c  | 136 ++++++++++++++++++++++++++++++++++++
 drivers/mfd/nct6694-usb.c   |  95 +++----------------------
 include/linux/mfd/nct6694.h |   9 ++-
 5 files changed, 155 insertions(+), 88 deletions(-)
 create mode 100644 drivers/mfd/nct6694-core.c

diff --git a/MAINTAINERS b/MAINTAINERS
index d52a3028e7c0..53a81f8afc37 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19098,7 +19098,7 @@ S:	Supported
 F:	drivers/gpio/gpio-nct6694.c
 F:	drivers/hwmon/nct6694-hwmon.c
 F:	drivers/i2c/busses/i2c-nct6694.c
-F:	drivers/mfd/nct6694-usb.c
+F:	drivers/mfd/nct6694-*.c
 F:	drivers/net/can/usb/nct6694_canfd.c
 F:	drivers/rtc/rtc-nct6694.c
 F:	drivers/watchdog/nct6694_wdt.c
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 361c5360e656..668a69dc66a7 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -124,6 +124,7 @@ obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
 
 obj-$(CONFIG_MFD_PF1550)	+= pf1550.o
 
+obj-$(CONFIG_MFD_NCT6694)	+= nct6694-core.o
 obj-$(CONFIG_MFD_NCT6694_USB)	+= nct6694-usb.o
 
 obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
diff --git a/drivers/mfd/nct6694-core.c b/drivers/mfd/nct6694-core.c
new file mode 100644
index 000000000000..a2afd5f33ea5
--- /dev/null
+++ b/drivers/mfd/nct6694-core.c
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2026 Nuvoton Technology Corp.
+ *
+ * Nuvoton NCT6694 MFD core driver.
+ *
+ * This provides common registration for IRQ domain, IDA pools,
+ * and MFD sub-devices shared by all transport drivers (USB, HIF).
+ */
+
+#include <linux/idr.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/spinlock.h>
+
+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);
+
+	guard(spinlock_irqsave)(&nct6694->irq_lock);
+
+	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);
+
+	guard(spinlock_irqsave)(&nct6694->irq_lock);
+
+	nct6694->irq_enable &= ~BIT(hwirq);
+}
+
+static const struct irq_chip nct6694_irq_chip = {
+	.name = "nct6694-irq",
+	.flags = IRQCHIP_SKIP_SET_WAKE,
+	.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,
+};
+
+/**
+ * nct6694_core_probe() - Register IRQ domain, IDAs, and MFD sub-devices
+ * @dev: parent device (USB interface or platform device)
+ * @nct6694: initialized nct6694 structure with transport callbacks set
+ *
+ * This function completes the common probe steps shared by all transport
+ * drivers: IRQ domain creation, IDA initialization, and MFD cell registration.
+ *
+ * The caller must have already set nct6694->dev, nct6694->priv,
+ * nct6694->read_msg, and nct6694->write_msg before calling this.
+ *
+ * Return: 0 on success or negative errno on failure.
+ */
+int nct6694_core_probe(struct device *dev, struct nct6694 *nct6694,
+		       const struct mfd_cell *cells, int n_cells)
+{
+	int ret;
+
+	spin_lock_init(&nct6694->irq_lock);
+
+	ida_init(&nct6694->gpio_ida);
+	ida_init(&nct6694->i2c_ida);
+	ida_init(&nct6694->canfd_ida);
+	ida_init(&nct6694->wdt_ida);
+
+	nct6694->domain = irq_domain_create_simple(NULL, NCT6694_NR_IRQS, 0,
+						   &nct6694_irq_domain_ops,
+						   nct6694);
+	if (!nct6694->domain) {
+		ret = -ENODEV;
+		goto err_ida;
+	}
+
+	ret = mfd_add_hotplug_devices(dev, cells, n_cells);
+	if (ret)
+		goto err_domain;
+
+	return 0;
+
+err_domain:
+	irq_domain_remove(nct6694->domain);
+err_ida:
+	ida_destroy(&nct6694->wdt_ida);
+	ida_destroy(&nct6694->canfd_ida);
+	ida_destroy(&nct6694->i2c_ida);
+	ida_destroy(&nct6694->gpio_ida);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nct6694_core_probe);
+
+/**
+ * nct6694_core_remove() - Unregister MFD sub-devices and free core resources
+ * @nct6694: nct6694 structure previously passed to nct6694_core_probe()
+ */
+void nct6694_core_remove(struct nct6694 *nct6694)
+{
+	mfd_remove_devices(nct6694->dev);
+	irq_domain_remove(nct6694->domain);
+	ida_destroy(&nct6694->wdt_ida);
+	ida_destroy(&nct6694->canfd_ida);
+	ida_destroy(&nct6694->i2c_ida);
+	ida_destroy(&nct6694->gpio_ida);
+}
+EXPORT_SYMBOL_GPL(nct6694_core_remove);
+
+MODULE_DESCRIPTION("Nuvoton NCT6694 MFD core driver");
+MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/mfd/nct6694-usb.c b/drivers/mfd/nct6694-usb.c
index 289580bbc472..666ad1c442b8 100644
--- a/drivers/mfd/nct6694-usb.c
+++ b/drivers/mfd/nct6694-usb.c
@@ -10,7 +10,6 @@
  */
 
 #include <linux/bits.h>
-#include <linux/idr.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/irqdomain.h>
@@ -19,7 +18,6 @@
 #include <linux/mfd/nct6694.h>
 #include <linux/module.h>
 #include <linux/slab.h>
-#include <linux/spinlock.h>
 #include <linux/usb.h>
 
 #define NCT6694_VENDOR_ID	0x0416
@@ -43,7 +41,7 @@ struct nct6694_usb_data {
 	__le32 *int_buffer;
 };
 
-static const struct mfd_cell nct6694_devs[] = {
+static const struct mfd_cell nct6694_usb_devs[] = {
 	MFD_CELL_NAME("nct6694-gpio"),
 	MFD_CELL_NAME("nct6694-gpio"),
 	MFD_CELL_NAME("nct6694-gpio"),
@@ -244,57 +242,9 @@ static void usb_int_callback(struct urb *urb)
 resubmit:
 	ret = usb_submit_urb(urb, GFP_ATOMIC);
 	if (ret)
-		dev_warn(nct6694->dev, "Failed to resubmit urb, status %pe",  ERR_PTR(ret));
+		dev_warn(nct6694->dev, "Failed to resubmit urb, status %pe", ERR_PTR(ret));
 }
 
-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);
-
-	guard(spinlock_irqsave)(&nct6694->irq_lock);
-
-	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);
-
-	guard(spinlock_irqsave)(&nct6694->irq_lock);
-
-	nct6694->irq_enable &= ~BIT(hwirq);
-}
-
-static const struct irq_chip nct6694_irq_chip = {
-	.name = "nct6694-irq",
-	.flags = IRQCHIP_SKIP_SET_WAKE,
-	.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)
 {
@@ -328,37 +278,21 @@ static int nct6694_usb_probe(struct usb_interface *iface,
 
 	udata->udev = udev;
 
+	nct6694->dev = dev;
 	nct6694->priv = udata;
 	nct6694->read_msg = nct6694_usb_read_msg;
 	nct6694->write_msg = nct6694_usb_write_msg;
 
-	nct6694->domain = irq_domain_create_simple(NULL, NCT6694_NR_IRQS, 0,
-						   &nct6694_irq_domain_ops,
-						   nct6694);
-	if (!nct6694->domain) {
-		ret = -ENODEV;
-		goto err_urb;
-	}
-
-	nct6694->dev = dev;
-
-	ida_init(&nct6694->gpio_ida);
-	ida_init(&nct6694->i2c_ida);
-	ida_init(&nct6694->canfd_ida);
-	ida_init(&nct6694->wdt_ida);
-
-	spin_lock_init(&nct6694->irq_lock);
-
 	ret = devm_mutex_init(dev, &udata->access_lock);
 	if (ret)
-		goto err_ida;
+		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_ida;
+		goto err_urb;
 	}
 
 	usb_fill_int_urb(udata->int_in_urb, udev, usb_rcvintpipe(udev, NCT6694_INT_IN_EP),
@@ -367,11 +301,11 @@ static int nct6694_usb_probe(struct usb_interface *iface,
 
 	ret = usb_submit_urb(udata->int_in_urb, GFP_KERNEL);
 	if (ret)
-		goto err_ida;
+		goto err_urb;
 
 	usb_set_intfdata(iface, nct6694);
 
-	ret = mfd_add_hotplug_devices(dev, nct6694_devs, ARRAY_SIZE(nct6694_devs));
+	ret = nct6694_core_probe(dev, nct6694, nct6694_usb_devs, ARRAY_SIZE(nct6694_usb_devs));
 	if (ret)
 		goto err_mfd;
 
@@ -379,12 +313,6 @@ static int nct6694_usb_probe(struct usb_interface *iface,
 
 err_mfd:
 	usb_kill_urb(udata->int_in_urb);
-err_ida:
-	ida_destroy(&nct6694->wdt_ida);
-	ida_destroy(&nct6694->canfd_ida);
-	ida_destroy(&nct6694->i2c_ida);
-	ida_destroy(&nct6694->gpio_ida);
-	irq_domain_remove(nct6694->domain);
 err_urb:
 	usb_free_urb(udata->int_in_urb);
 	return ret;
@@ -395,13 +323,8 @@ static void nct6694_usb_disconnect(struct usb_interface *iface)
 	struct nct6694 *nct6694 = usb_get_intfdata(iface);
 	struct nct6694_usb_data *udata = nct6694->priv;
 
-	mfd_remove_devices(nct6694->dev);
+	nct6694_core_remove(nct6694);
 	usb_kill_urb(udata->int_in_urb);
-	ida_destroy(&nct6694->wdt_ida);
-	ida_destroy(&nct6694->canfd_ida);
-	ida_destroy(&nct6694->i2c_ida);
-	ida_destroy(&nct6694->gpio_ida);
-	irq_domain_remove(nct6694->domain);
 	usb_free_urb(udata->int_in_urb);
 }
 
@@ -419,6 +342,6 @@ static struct usb_driver nct6694_usb_driver = {
 };
 module_usb_driver(nct6694_usb_driver);
 
-MODULE_DESCRIPTION("Nuvoton NCT6694 core driver");
+MODULE_DESCRIPTION("Nuvoton NCT6694 USB transport driver");
 MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
 MODULE_LICENSE("GPL");
diff --git a/include/linux/mfd/nct6694.h b/include/linux/mfd/nct6694.h
index 3079c74110aa..a150c7d6ceba 100644
--- a/include/linux/mfd/nct6694.h
+++ b/include/linux/mfd/nct6694.h
@@ -10,10 +10,13 @@
 #define __MFD_NCT6694_H
 
 #include <linux/idr.h>
-#include <linux/mutex.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
 
+struct device;
+struct irq_domain;
+struct mfd_cell;
+
 #define NCT6694_HWMON_MOD	0x00
 #define NCT6694_PWM_MOD		0x01
 #define NCT6694_I2C_MOD		0x03
@@ -115,4 +118,8 @@ static inline int nct6694_write_msg(struct nct6694 *nct6694,
 	return nct6694->write_msg(nct6694, cmd_hd, buf);
 }
 
+int nct6694_core_probe(struct device *dev, struct nct6694 *nct6694,
+		       const struct mfd_cell *cells, int n_cells);
+void nct6694_core_remove(struct nct6694 *nct6694);
+
 #endif
-- 
2.34.1

[PATCH v5 7/7] mfd: nct6694: Add Host Interface (HIF) eSPI transport driver

[a0282524688]

From: Ming Yu <a0282524688@gmail.com>

Add support for the Host Interface (HIF) transport via eSPI for the
Nuvoton NCT6694 peripheral expander.

This transport driver initializes the Super-I/O to configure the
device's shared memory base address and SIRQ. It provides the required
I/O callbacks (read_msg/write_msg) utilizing memory-mapped I/O and
regmap for command transactions. The initialized device config is then
passed to the MFD core (nct6694_core_probe) for sub-device registration
and IRQ domain setup.

Signed-off-by: Ming Yu <a0282524688@gmail.com>
---
Changes since version 4:
- Split from the monolithic v4 patch.
- Adapted to re-use the newly introduced nct6694_core_probe() and 
  abstracted I/O APIs.

Changes since version 3:
- Remove redundant module type macro definitions from sub-device drivers
  that are now provided by the shared header <linux/mfd/nct6694.h>,
  fixing -Wmacro-redefined warnings.

Changes since version 2:
- Restore per-device IDA and mfd_add_hotplug_devices()/PLATFORM_DEVID_AUTO
  to avoid child device ID conflicts with multiple NCT6694 chips.
- Validate irq_find_mapping() return value before dispatching IRQs.
- Check superio_enter() return value in nct6694_irq_init().

Changes since version 1:
- Drop function pointers from Super-I/O access and use static inline
  helpers with proper types.

 drivers/mfd/Kconfig       |  16 ++
 drivers/mfd/Makefile      |   1 +
 drivers/mfd/nct6694-hif.c | 529 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 546 insertions(+)
 create mode 100644 drivers/mfd/nct6694-hif.c

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index b5b30371da59..a67c73f1fdd4 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1174,6 +1174,22 @@ config MFD_NCT6694
 
 	  It is selected automatically by the transport interface drivers.
 
+config MFD_NCT6694_HIF
+	tristate "Nuvoton NCT6694 HIF (eSPI) interface support"
+	depends on HAS_IOPORT && ACPI
+	select MFD_NCT6694
+	select REGMAP_MMIO
+	help
+	  This enables support for the Nuvoton NCT6694 peripheral expander
+	  connected via the Host Interface (HIF) using eSPI transport.
+
+	  The transport driver uses Super-I/O mapping and shared memory to
+	  communicate with the NCT6694 firmware. Enable this option if you
+	  are using the NCT6694 over an eSPI interface on an ACPI platform.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called nct6694-hif.
+
 config MFD_NCT6694_USB
 	tristate "Nuvoton NCT6694 USB interface support"
 	select MFD_NCT6694
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 668a69dc66a7..a0ce7d79c4f2 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -125,6 +125,7 @@ obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
 obj-$(CONFIG_MFD_PF1550)	+= pf1550.o
 
 obj-$(CONFIG_MFD_NCT6694)	+= nct6694-core.o
+obj-$(CONFIG_MFD_NCT6694_HIF)	+= nct6694-hif.o
 obj-$(CONFIG_MFD_NCT6694_USB)	+= nct6694-usb.o
 
 obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
diff --git a/drivers/mfd/nct6694-hif.c b/drivers/mfd/nct6694-hif.c
new file mode 100644
index 000000000000..0a8273f4b1a1
--- /dev/null
+++ b/drivers/mfd/nct6694-hif.c
@@ -0,0 +1,529 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2026 Nuvoton Technology Corp.
+ *
+ * Nuvoton NCT6694 host-interface (eSPI) transport driver.
+ */
+
+#include <linux/acpi.h>
+#include <linux/bits.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.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/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/unaligned.h>
+
+#define DRVNAME "nct6694-hif"
+
+#define NCT6694_POLL_INTERVAL_US	10
+#define NCT6694_POLL_TIMEOUT_US		10000
+
+/*
+ * Super-I/O registers
+ */
+#define SIO_REG_LDSEL		0x07	/* Logical device select */
+#define SIO_REG_DEVID		0x20	/* Device ID (2 bytes) */
+#define SIO_REG_LD_SHM		0x0F	/* Logical device shared memory control */
+
+#define SIO_REG_SHM_ENABLE	0x30	/* Enable shared memory */
+#define SIO_REG_SHM_BASE_ADDR	0x60	/* Shared memory base address (2 bytes) */
+#define SIO_REG_SHM_IRQ_NR	0x70	/* Shared memory interrupt number */
+
+#define SIO_REG_UNLOCK_KEY	0x87	/* Key to enable Super-I/O */
+#define SIO_REG_LOCK_KEY	0xAA	/* Key to disable Super-I/O */
+
+#define SIO_NCT6694B_ID		0xD029
+#define SIO_NCT6694D_ID		0x5832
+
+/*
+ * Super-I/O Shared Memory Logical Device registers
+ */
+#define NCT6694_SHM_COFS_STS			0x2E
+#define NCT6694_SHM_COFS_STS_COFS4W		BIT(7)
+
+#define NCT6694_SHM_COFS_CTL2			0x3B
+#define NCT6694_SHM_COFS_CTL2_COFS4W_IE		BIT(3)
+
+#define NCT6694_SHM_INTR_STATUS			0x9C	/* Interrupt status register (4 bytes) */
+
+enum nct6694_chips {
+	NCT6694B = 0,
+	NCT6694D,
+};
+
+struct __packed nct6694_msg {
+	struct nct6694_cmd_header cmd_header;
+	struct nct6694_response_header response_header;
+	unsigned char data[];
+};
+
+struct nct6694_sio_data {
+	enum nct6694_chips chip;
+	int sioreg;	/* Super-I/O index port */
+};
+
+struct nct6694_hif_data {
+	struct regmap *regmap;
+	struct mutex msg_lock;
+	struct nct6694_sio_data *sio_data;
+	void __iomem *msg_base;
+	unsigned int shm_base;
+};
+
+static const char * const nct6694_chip_names[] = {
+	[NCT6694B] = "NCT6694B",
+	[NCT6694D] = "NCT6694D",
+};
+
+/*
+ * Super-I/O functions.
+ */
+static inline int superio_enter(struct nct6694_sio_data *sio_data)
+{
+	int ioreg = sio_data->sioreg;
+
+	/*
+	 * Try to reserve <ioreg> and <ioreg + 1> for exclusive access.
+	 */
+	if (!request_muxed_region(ioreg, 2, DRVNAME))
+		return -EBUSY;
+
+	outb(SIO_REG_UNLOCK_KEY, ioreg);
+	outb(SIO_REG_UNLOCK_KEY, ioreg);
+
+	return 0;
+}
+
+static inline void superio_exit(struct nct6694_sio_data *sio_data)
+{
+	int ioreg = sio_data->sioreg;
+
+	outb(SIO_REG_LOCK_KEY, ioreg);
+
+	release_region(ioreg, 2);
+}
+
+static inline void superio_select(struct nct6694_sio_data *sio_data, int ld)
+{
+	int ioreg = sio_data->sioreg;
+
+	outb(SIO_REG_LDSEL, ioreg);
+	outb(ld, ioreg + 1);
+}
+
+static inline int superio_inb(struct nct6694_sio_data *sio_data, int reg)
+{
+	int ioreg = sio_data->sioreg;
+
+	outb(reg, ioreg);
+	return inb(ioreg + 1);
+}
+
+static inline int superio_inw(struct nct6694_sio_data *sio_data, int reg)
+{
+	int ioreg = sio_data->sioreg;
+	int val;
+
+	outb(reg++, ioreg);
+	val = inb(ioreg + 1) << 8;
+	outb(reg, ioreg);
+	val |= inb(ioreg + 1);
+
+	return val;
+}
+
+static inline void superio_outb(struct nct6694_sio_data *sio_data, int reg, u8 val)
+{
+	int ioreg = sio_data->sioreg;
+
+	outb(reg, ioreg);
+	outb(val, ioreg + 1);
+}
+
+static int nct6694_sio_find(struct nct6694_sio_data *sio_data, u8 sioreg)
+{
+	int ret;
+	u16 devid;
+
+	sio_data->sioreg = sioreg;
+
+	ret = superio_enter(sio_data);
+	if (ret)
+		return ret;
+
+	/* Check Chip ID */
+	devid = superio_inw(sio_data, SIO_REG_DEVID);
+	switch (devid) {
+	case SIO_NCT6694B_ID:
+		sio_data->chip = NCT6694B;
+		break;
+	case SIO_NCT6694D_ID:
+		sio_data->chip = NCT6694D;
+		break;
+	default:
+		pr_debug("Unsupported device ID: 0x%04x\n", devid);
+		goto err;
+	}
+
+	pr_info("Found %s at %#x\n", nct6694_chip_names[sio_data->chip], sio_data->sioreg);
+
+	superio_exit(sio_data);
+
+	return 0;
+
+err:
+	superio_exit(sio_data);
+	return -ENODEV;
+}
+
+static const struct mfd_cell nct6694_hif_devs[] = {
+	MFD_CELL_NAME("nct6694-gpio"),
+	MFD_CELL_NAME("nct6694-gpio"),
+	MFD_CELL_NAME("nct6694-gpio"),
+	MFD_CELL_NAME("nct6694-gpio"),
+	MFD_CELL_NAME("nct6694-gpio"),
+	MFD_CELL_NAME("nct6694-gpio"),
+	MFD_CELL_NAME("nct6694-gpio"),
+	MFD_CELL_NAME("nct6694-gpio"),
+	MFD_CELL_NAME("nct6694-gpio"),
+	MFD_CELL_NAME("nct6694-gpio"),
+	MFD_CELL_NAME("nct6694-gpio"),
+	MFD_CELL_NAME("nct6694-gpio"),
+	MFD_CELL_NAME("nct6694-gpio"),
+	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"),
+	MFD_CELL_NAME("nct6694-i2c"),
+	MFD_CELL_NAME("nct6694-i2c"),
+	MFD_CELL_NAME("nct6694-i2c"),
+
+	MFD_CELL_NAME("nct6694-canfd"),
+	MFD_CELL_NAME("nct6694-canfd"),
+};
+
+static int nct6694_response_err_handling(struct nct6694 *nct6694, unsigned char err_status)
+{
+	switch (err_status) {
+	case NCT6694_NO_ERROR:
+		return 0;
+	case NCT6694_NOT_SUPPORT_ERROR:
+		dev_err(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_err(nct6694->dev, "Command is pending!\n");
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return -EIO;
+}
+
+static int nct6694_xfer_msg(struct nct6694 *nct6694,
+			    const struct nct6694_cmd_header *cmd_hd,
+			    u8 hctrl, void *buf)
+{
+	struct nct6694_hif_data *hdata = nct6694->priv;
+	void __iomem *hdr = hdata->msg_base + offsetof(struct nct6694_msg, cmd_header);
+	struct nct6694_cmd_header cmd = *cmd_hd;
+	struct nct6694_response_header resp;
+	u16 len = le16_to_cpu(cmd.len);
+	u8 status;
+	int ret;
+
+	guard(mutex)(&hdata->msg_lock);
+
+	/* Wait until the previous command is completed */
+	ret = readb_poll_timeout(hdr + offsetof(struct nct6694_cmd_header, hctrl),
+				 status, status == 0, NCT6694_POLL_INTERVAL_US,
+				 NCT6694_POLL_TIMEOUT_US);
+	if (ret)
+		return ret;
+
+	/*
+	 * Write cmd header fields, but skip hctrl — writing to it triggers
+	 * firmware command processing and must be deferred until data is ready.
+	 */
+	memcpy_toio(hdr, &cmd, offsetof(struct nct6694_cmd_header, hctrl));
+	memcpy_toio(hdr + offsetof(struct nct6694_cmd_header, rsv2), &cmd.rsv2,
+		    sizeof(cmd) - offsetof(struct nct6694_cmd_header, rsv2));
+
+	if (hctrl == NCT6694_HCTRL_SET && len)
+		memcpy_toio(hdata->msg_base + offsetof(struct nct6694_msg, data),
+			    buf, len);
+
+	/* Write hctrl last to trigger command processing */
+	writeb(hctrl, hdr + offsetof(struct nct6694_cmd_header, hctrl));
+
+	ret = readb_poll_timeout(hdr + offsetof(struct nct6694_cmd_header, hctrl),
+				 status, status == 0, NCT6694_POLL_INTERVAL_US,
+				 NCT6694_POLL_TIMEOUT_US);
+	if (ret)
+		return ret;
+
+	memcpy_fromio(&resp, hdata->msg_base + offsetof(struct nct6694_msg, response_header),
+		      sizeof(resp));
+
+	ret = nct6694_response_err_handling(nct6694, resp.sts);
+	if (ret)
+		return ret;
+
+	if (le16_to_cpu(resp.len))
+		memcpy_fromio(buf, hdata->msg_base + offsetof(struct nct6694_msg, data),
+			      min(len, le16_to_cpu(resp.len)));
+
+	return 0;
+}
+
+/**
+ * nct6694_hif_read_msg() - Send a command and read response data via HIF
+ * @nct6694: NCT6694 device data
+ * @cmd_hd: command header
+ * @buf: buffer to store response data
+ *
+ * Return: 0 on success or negative errno on failure.
+ */
+static int nct6694_hif_read_msg(struct nct6694 *nct6694,
+				const struct nct6694_cmd_header *cmd_hd,
+				void *buf)
+{
+	struct nct6694_hif_data *hdata = nct6694->priv;
+
+	if (cmd_hd->mod == NCT6694_RPT_MOD)
+		return regmap_bulk_read(hdata->regmap,
+					le16_to_cpu(cmd_hd->offset),
+					buf, le16_to_cpu(cmd_hd->len));
+	return nct6694_xfer_msg(nct6694, cmd_hd, NCT6694_HCTRL_GET, buf);
+}
+
+/**
+ * nct6694_hif_write_msg() - Send a command with data payload via HIF
+ * @nct6694: NCT6694 device data
+ * @cmd_hd: command header
+ * @buf: buffer containing data to send
+ *
+ * Return: 0 on success or negative errno on failure.
+ */
+static int nct6694_hif_write_msg(struct nct6694 *nct6694,
+				 const struct nct6694_cmd_header *cmd_hd,
+				 void *buf)
+{
+	struct nct6694_hif_data *hdata = nct6694->priv;
+
+	if (cmd_hd->mod == NCT6694_RPT_MOD)
+		return regmap_bulk_write(hdata->regmap,
+					 le16_to_cpu(cmd_hd->offset),
+					 buf, le16_to_cpu(cmd_hd->len));
+	return nct6694_xfer_msg(nct6694, cmd_hd, NCT6694_HCTRL_SET, buf);
+}
+
+static const struct regmap_config nct6694_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.reg_stride = 1,
+};
+
+static irqreturn_t nct6694_irq_handler(int irq, void *data)
+{
+	struct nct6694 *nct6694 = data;
+	struct nct6694_hif_data *hdata = nct6694->priv;
+	u8 reg_data[4];
+	u32 intr_status;
+	int ret;
+
+	/* Check interrupt status is set */
+	if (!(inb(hdata->shm_base + NCT6694_SHM_COFS_STS) & NCT6694_SHM_COFS_STS_COFS4W))
+		return IRQ_NONE;
+
+	/* Clear interrupt status */
+	outb(NCT6694_SHM_COFS_STS_COFS4W, hdata->shm_base + NCT6694_SHM_COFS_STS);
+
+	ret = regmap_bulk_read(hdata->regmap, NCT6694_SHM_INTR_STATUS,
+			       reg_data, ARRAY_SIZE(reg_data));
+	if (ret)
+		return IRQ_NONE;
+
+	intr_status = get_unaligned_le32(reg_data);
+
+	while (intr_status) {
+		int hwirq = __ffs(intr_status);
+		unsigned int virq = irq_find_mapping(nct6694->domain, hwirq);
+
+		if (virq)
+			generic_handle_irq_safe(virq);
+		intr_status &= ~BIT(hwirq);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static void nct6694_irq_release(void *data)
+{
+	struct nct6694 *nct6694 = data;
+	struct nct6694_hif_data *hdata = nct6694->priv;
+	unsigned char cofs_ctl2;
+
+	/* Disable SIRQ interrupt */
+	cofs_ctl2 = inb(hdata->shm_base + NCT6694_SHM_COFS_CTL2);
+	cofs_ctl2 &= ~NCT6694_SHM_COFS_CTL2_COFS4W_IE;
+	outb(cofs_ctl2, hdata->shm_base + NCT6694_SHM_COFS_CTL2);
+}
+
+static int nct6694_irq_init(struct nct6694 *nct6694, int irq)
+{
+	struct nct6694_hif_data *hdata = nct6694->priv;
+	struct nct6694_sio_data *sio_data = hdata->sio_data;
+	unsigned char cofs_ctl2;
+	int ret;
+
+	/* Set SIRQ number */
+	ret = superio_enter(sio_data);
+	if (ret)
+		return ret;
+
+	superio_select(sio_data, SIO_REG_LD_SHM);
+
+	if (!superio_inb(sio_data, SIO_REG_SHM_ENABLE)) {
+		superio_exit(sio_data);
+		return -EIO;
+	}
+
+	hdata->shm_base = superio_inw(sio_data, SIO_REG_SHM_BASE_ADDR);
+
+	superio_outb(sio_data, SIO_REG_SHM_IRQ_NR, irq);
+
+	superio_exit(sio_data);
+
+	/* Enable SIRQ interrupt */
+	cofs_ctl2 = inb(hdata->shm_base + NCT6694_SHM_COFS_CTL2);
+	cofs_ctl2 |= NCT6694_SHM_COFS_CTL2_COFS4W_IE;
+	outb(cofs_ctl2, hdata->shm_base + NCT6694_SHM_COFS_CTL2);
+
+	return 0;
+}
+
+static void nct6694_core_remove_action(void *data)
+{
+	struct nct6694 *nct6694 = data;
+
+	nct6694_core_remove(nct6694);
+}
+
+static const u8 sio_addrs[] = { 0x2e, 0x4e };
+
+static int nct6694_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct nct6694_sio_data *sio_data;
+	struct nct6694_hif_data *hdata;
+	struct nct6694 *data;
+	void __iomem *rpt_base, *msg_base;
+	int ret, i, irq;
+
+	sio_data = devm_kzalloc(dev, sizeof(*sio_data), GFP_KERNEL);
+	if (!sio_data)
+		return -ENOMEM;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	hdata = devm_kzalloc(dev, sizeof(*hdata), GFP_KERNEL);
+	if (!hdata)
+		return -ENOMEM;
+
+	rpt_base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(rpt_base))
+		return PTR_ERR(rpt_base);
+	msg_base = devm_platform_ioremap_resource(pdev, 1);
+	if (IS_ERR(msg_base))
+		return PTR_ERR(msg_base);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	for (i = 0; i < ARRAY_SIZE(sio_addrs); i++) {
+		ret = nct6694_sio_find(sio_data, sio_addrs[i]);
+		if (!ret)
+			break;
+	}
+	if (ret)
+		return ret;
+
+	hdata->sio_data = sio_data;
+	hdata->msg_base = msg_base;
+	hdata->regmap = devm_regmap_init_mmio(dev, rpt_base, &nct6694_regmap_config);
+	if (IS_ERR(hdata->regmap))
+		return PTR_ERR(hdata->regmap);
+
+	data->dev = dev;
+	data->priv = hdata;
+	data->read_msg = nct6694_hif_read_msg;
+	data->write_msg = nct6694_hif_write_msg;
+
+	ret = devm_mutex_init(dev, &hdata->msg_lock);
+	if (ret)
+		return ret;
+
+	ret = nct6694_core_probe(dev, data, nct6694_hif_devs, ARRAY_SIZE(nct6694_hif_devs));
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(dev, nct6694_core_remove_action, data);
+	if (ret)
+		return ret;
+
+	ret = nct6694_irq_init(data, irq);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(dev, nct6694_irq_release, data);
+	if (ret)
+		return ret;
+
+	ret = devm_request_threaded_irq(dev, irq, NULL, nct6694_irq_handler,
+					IRQF_ONESHOT | IRQF_SHARED,
+					dev_name(dev), data);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, data);
+
+	return 0;
+}
+
+static const struct acpi_device_id nct6694_acpi_ids[] = {
+	{ "NTN0538", 0 },
+	{}
+};
+
+static struct platform_driver nct6694_driver = {
+	.driver = {
+		.name = DRVNAME,
+		.acpi_match_table = nct6694_acpi_ids,
+	},
+	.probe	= nct6694_probe,
+};
+module_platform_driver(nct6694_driver);
+
+MODULE_DESCRIPTION("Nuvoton NCT6694 host-interface transport driver");
+MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
+MODULE_LICENSE("GPL");
-- 
2.34.1