soc: ti: Add wkup_m3_ipc driver

Introduce a wkup_m3_ipc driver to handle communication between the MPU
and Cortex M3 wkup_m3 present on am335x.

This driver is responsible for actually booting the wkup_m3_rproc and
also handling all IPC which is done using the IPC registers in the control
module, a mailbox, and a separate interrupt back from the wkup_m3. A small
API is exposed for executing specific power commands, which include
configuring for low power mode, request a transition to a low power mode,
and status info on a previous transition.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

drivers/soc/ti/Kconfig

@@ -28,4 +28,14 @@ config KEYSTONE_NAVIGATOR_DMA
 
 	  If unsure, say N.
 
+config WKUP_M3_IPC
+	tristate "TI AMx3 Wkup-M3 IPC Driver"
+	depends on WKUP_M3_RPROC
+	depends on OMAP2PLUS_MBOX
+	help
+	  TI AM33XX and AM43XX have a Cortex M3, the Wakeup M3, to handle
+	  low power transitions. This IPC driver provides the necessary API
+	  to communicate and use the Wakeup M3 for PM features like suspend
+	  resume and boots it using wkup_m3_rproc driver.
+
 endif # SOC_TI

drivers/soc/ti/Makefile

@@ -4,3 +4,4 @@
 obj-$(CONFIG_KEYSTONE_NAVIGATOR_QMSS)	+= knav_qmss.o
 knav_qmss-y := knav_qmss_queue.o knav_qmss_acc.o
 obj-$(CONFIG_KEYSTONE_NAVIGATOR_DMA)	+= knav_dma.o
+obj-$(CONFIG_WKUP_M3_IPC)		+= wkup_m3_ipc.o