powerpc/4xx: Add suspend and idle support

Add suspend/resume support for 4xx compatible CPUs.
See /sys/power/state for available power states configured in.

Add two different idle states (idle-wait and idle-doze) controlled via sysfs.
Default is idle-wait.
	cat /sys/devices/system/cpu/cpu0/idle
	[wait] doze

To save additional power, use idle-doze.
	echo doze > /sys/devices/system/cpu/cpu0/idle
	cat /sys/devices/system/cpu/cpu0/idle
	wait [doze]

Signed-off-by: Victor Gallardo <[email protected]>
Signed-off-by: Josh Boyer <[email protected]>

Documentation/powerpc/dts-bindings/4xx/cpm.txt

@@ -0,0 +1,52 @@
+PPC4xx Clock Power Management (CPM) node
+
+Required properties:
+	- compatible		: compatible list, currently only "ibm,cpm"
+	- dcr-access-method	: "native"
+	- dcr-reg		: < DCR register range >
+
+Optional properties:
+	- er-offset		: All 4xx SoCs with a CPM controller have
+				  one of two different order for the CPM
+				  registers. Some have the CPM registers
+				  in the following order (ER,FR,SR). The
+				  others have them in the following order
+				  (SR,ER,FR). For the second case set
+				  er-offset = <1>.
+	- unused-units		: specifier consist of one cell. For each
+				  bit in the cell, the corresponding bit
+				  in CPM will be set to turn off unused
+				  devices.
+	- idle-doze		: specifier consist of one cell. For each
+				  bit in the cell, the corresponding bit
+				  in CPM will be set to turn off unused
+				  devices. This is usually just CPM[CPU].
+	- standby		: specifier consist of one cell. For each
+				  bit in the cell, the corresponding bit
+				  in CPM will be set on standby and
+				  restored on resume.
+	- suspend		: specifier consist of one cell. For each
+				  bit in the cell, the corresponding bit
+				  in CPM will be set on suspend (mem) and
+				  restored on resume. Note, for standby
+				  and suspend the corresponding bits can
+				  be different or the same. Usually for
+				  standby only class 2 and 3 units are set.
+				  However, the interface does not care.
+				  If they are the same, the additional
+				  power saving will be seeing if support
+				  is available to put the DDR in self
+				  refresh mode and any additional power
+				  saving techniques for the specific SoC.
+
+Example:
+	CPM0: cpm {
+		compatible = "ibm,cpm";
+		dcr-access-method = "native";
+		dcr-reg = <0x160 0x003>;
+		er-offset = <0>;
+		unused-units = <0x00000100>;
+		idle-doze = <0x02000000>;
+		standby = <0xfeff0000>;
+		suspend = <0xfeff791d>;
+};