drivers: bus: Add Simple Power-Managed Bus Driver

Add a driver for transparent busses that don't need a real driver, but
where the bus controller is part of a PM domain, or under the control of
a functional clock.  Typically, the bus controller's PM domain and/or
clock must be enabled for child devices connected to the bus (either
on-SoC or externally) to function.

Hence the sole purpose of this driver is to enable its clock and PM
domain (if exist(s)), which are specified in the DT and managed from
platform and PM domain code, and to probe for child devices.

Due to the child-parent relationship with devices connected to the bus,
PM domain and clock state transitions are handled in the correct order.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com>
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index 626960819e6d..7e9c2674af81 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -58,6 +58,19 @@ config OMAP_OCP2SCP
           OCP2SCP and in OMAP5, both USB PHY and SATA PHY is connected via
           OCP2SCP.
 
+config SIMPLE_PM_BUS
+        bool "Simple Power-Managed Bus Driver"
+        depends on OF && PM
+        depends on ARCH_SHMOBILE || COMPILE_TEST
+        help
+          Driver for transparent busses that don't need a real driver, but
+          where the bus controller is part of a PM domain, or under the control
+          of a functional clock, and thus relies on runtime PM for managing
+          this PM domain and/or clock.
+          An example of such a bus controller is the Renesas Bus State
+          Controller (BSC, sometimes called "LBSC within Bus Bridge", or
+          "External Bus Interface") as found on several Renesas ARM SoCs.
+
 config VEXPRESS_CONFIG
         bool "Versatile Express configuration bus"
         default y if ARCH_VEXPRESS