mfd: simple-mfd-i2c: Add Delta TN48M CPLD support

Delta TN48M switches have a Lattice CPLD that serves
multiple purposes including being a GPIO expander.

So, lets use the simple I2C MFD driver to provide the MFD core.

Also add a virtual symbol which pulls in the simple-mfd-i2c driver and
provide a common symbol on which the subdevice drivers can depend on.

Fixes: b3dcb5d ("gpio: Add Delta TN48M CPLD GPIO driver")
Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Link: https://lore.kernel.org/20220131133049.77780-2-robert.marko@sartura.hr
Link: https://lore.kernel.org/linux-gpio/20260112064950.3837737-1-rdunlap@infradead.org/
Signed-off-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260112-mfd-tn48m-v11-1-00c798d8cd2a@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

Author: robimarko

drivers/mfd/Kconfig

@@ -407,6 +407,17 @@ config MFD_CS47L92
 	help
 	  Support for Cirrus Logic CS42L92, CS47L92 and CS47L93 Smart Codecs
 
+config MFD_TN48M_CPLD
+	tristate "Delta Networks TN48M switch CPLD driver"
+	depends on I2C
+	depends on ARCH_MVEBU || COMPILE_TEST
+	select MFD_SIMPLE_MFD_I2C
+	help
+	  Select this option to enable support for Delta Networks TN48M switch
+	  CPLD. It consists of reset and GPIO drivers. CPLD provides GPIOS-s
+	  for the SFP slots as well as power supply related information.
+	  SFP support depends on the GPIO driver being selected.
+
 config PMIC_DA903X
 	bool "Dialog Semiconductor DA9030/DA9034 PMIC Support"
 	depends on I2C=y

drivers/mfd/simple-mfd-i2c.c

@@ -116,6 +116,7 @@ static const struct simple_mfd_data spacemit_p1 = {
 };
 
 static const struct of_device_id simple_mfd_i2c_of_match[] = {
+	{ .compatible = "delta,tn48m-cpld" },
 	{ .compatible = "fsl,ls1028aqds-fpga" },
 	{ .compatible = "fsl,lx2160aqds-fpga" },
 	{ .compatible = "fsl,lx2160ardb-fpga" },