[PATCH v8 12/13] mfd: nct6694: Add a Kconfig symbol for the USB transport

[a0282524688@gmail.com]

From: Ming Yu <a0282524688@gmail.com>

Now that the sub-device drivers only access the device through regmap,
the core no longer depends on USB.

Build the USB transport under a new MFD_NCT6694_USB symbol and keep
MFD_NCT6694 for the core. MFD_NCT6694_USB defaults to MFD_NCT6694 so
that existing configurations keep the USB transport enabled.

Signed-off-by: Ming Yu <a0282524688@gmail.com>
---
Changes in v8:
- New patch. Split out of v7 "Rename driver to nct6694-usb and update
  Kconfig"; MFD_NCT6694 remains the user visible core symbol and
  MFD_NCT6694_USB defaults to it to keep existing configurations
  working.

 drivers/mfd/Kconfig  | 20 ++++++++++++++++----
 drivers/mfd/Makefile |  2 +-
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index a0d9d6ccfb0c..de7d2171f514 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1167,18 +1167,30 @@ config MFD_NCT6694
 	tristate "Nuvoton NCT6694 support"
 	select MFD_CORE
 	select REGMAP
-	depends on USB
 	help
-	  This enables support for the Nuvoton USB device NCT6694, which shares
+	  This enables support for the Nuvoton NCT6694, which shares
 	  peripherals.
 	  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 provides core APIs to access the NCT6694 hardware
-	  monitoring and control features.
+	  This driver provides the core support shared by the transport
+	  interface drivers, at least one of which must be enabled.
 	  Additional drivers must be enabled to utilize the specific
 	  functionalities of the device.
 
+config MFD_NCT6694_USB
+	tristate "Nuvoton NCT6694 USB interface support"
+	depends on MFD_NCT6694 && USB
+	default MFD_NCT6694
+	help
+	  This enables support for the Nuvoton NCT6694 connected through
+	  its USB interface. The driver uses USB bulk transfers to send
+	  commands to the device firmware and an interrupt transfer to
+	  receive its interrupt status.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called nct6694-usb.
+
 config MFD_OCELOT
 	tristate "Microsemi Ocelot External Control Support"
 	depends on SPI_MASTER
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index dfd81356b485..a42b99250454 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -125,7 +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)	+= nct6694-usb.o
+obj-$(CONFIG_MFD_NCT6694_USB)	+= nct6694-usb.o
 
 obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
 
-- 
2.34.1