peci: Add peci-aspeed controller driver

ASPEED AST24xx/AST25xx/AST26xx SoCs support the PECI electrical
interface (a.k.a PECI wire) that provides a communication channel with
Intel processors.
This driver allows BMC to discover devices connected to it and
communicate with them using PECI protocol.

Co-developed-by: Iwona Winiarska <iwona.winiarska@intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Acked-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Signed-off-by: Iwona Winiarska <iwona.winiarska@intel.com>
Link: https://lore.kernel.org/r/20220208153639.255278-6-iwona.winiarska@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MAINTAINERS

@@ -2986,6 +2986,14 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/net/asix,ax88796c.yaml
 F:	drivers/net/ethernet/asix/ax88796c_*
 
+ASPEED PECI CONTROLLER
+M:	Iwona Winiarska <iwona.winiarska@intel.com>
+L:	linux-aspeed@lists.ozlabs.org (moderated for non-subscribers)
+L:	openbmc@lists.ozlabs.org (moderated for non-subscribers)
+S:	Supported
+F:	Documentation/devicetree/bindings/peci/peci-aspeed.yaml
+F:	drivers/peci/controller/peci-aspeed.c
+
 ASPEED PINCTRL DRIVERS
 M:	Andrew Jeffery <andrew@aj.id.au>
 L:	linux-aspeed@lists.ozlabs.org (moderated for non-subscribers)

drivers/peci/Kconfig

@@ -13,3 +13,9 @@ menuconfig PECI
 
 	  This support is also available as a module. If so, the module
 	  will be called peci.
+
+if PECI
+
+source "drivers/peci/controller/Kconfig"
+
+endif # PECI

drivers/peci/Makefile

@@ -3,3 +3,6 @@
 # Core functionality
 peci-y := core.o
 obj-$(CONFIG_PECI) += peci.o
+
+# Hardware specific bus drivers
+obj-y += controller/

drivers/peci/controller/Kconfig

@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+config PECI_ASPEED
+	tristate "ASPEED PECI support"
+	depends on ARCH_ASPEED || COMPILE_TEST
+	depends on OF
+	depends on HAS_IOMEM
+	depends on COMMON_CLK
+	help
+	  This option enables PECI controller driver for ASPEED AST2400,
+	  AST2500 and AST2600 SoCs. It allows BMC to discover devices
+	  connected to it, and communicate with them using PECI protocol.
+
+	  Say Y here if your system runs on ASPEED SoC and you are using it
+	  as BMC for Intel platform.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called peci-aspeed.

drivers/peci/controller/Makefile

@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+obj-$(CONFIG_PECI_ASPEED)	+= peci-aspeed.o