cpufreq: kirkwood: Add a cpufreq driver for Marvell Kirkwood SoCs

The Marvell Kirkwood SoCs have simple cpufreq support in hardware. The
CPU can either use the a high speed cpu clock, or the slower DDR
clock. Add a driver to swap between these two clock sources.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Jason Cooper <jason@lakedaemon.net>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/arm/kirkwood.txt b/Documentation/devicetree/bindings/arm/kirkwood.txt
new file mode 100644
index 000000000000..98cce9a653eb
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/kirkwood.txt
@@ -0,0 +1,27 @@
+Marvell Kirkwood Platforms Device Tree Bindings
+-----------------------------------------------
+
+Boards with a SoC of the Marvell Kirkwood
+shall have the following property:
+
+Required root node property:
+
+compatible: must contain "marvell,kirkwood";
+
+In order to support the kirkwood cpufreq driver, there must be a node
+cpus/cpu@0 with three clocks, "cpu_clk", "ddrclk" and "powersave",
+where the "powersave" clock is a gating clock used to switch the CPU
+between the "cpu_clk" and the "ddrclk".
+
+Example:
+
+        cpus {
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                cpu@0 {
+                      device_type = "cpu";
+                      compatible = "marvell,sheeva-88SV131";
+                      clocks = <&core_clk 1>, <&core_clk 3>, <&gate_clk 11>;
+                      clock-names = "cpu_clk", "ddrclk", "powersave";
+                };