[PATCH v5 04/14] of: document new emc-timings subnode in nvidia,tegra124-car

Tomeu Vizoso
2014-11-18T12:23:01Z

The EMC clock needs some extra information for changing its rate.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>

---

v5: * Remove constraint on the unit-address of the timings and timing subnodes

v4: * Remove comma from unit-address of CAR node in the example
* Simplify reg property value in the example
---
.../bindings/clock/nvidia,tegra124-car.txt | 42 +++++++++++++++++++++-
1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/clock/nvidia,tegra124-car.txt b/Documentation/devicetree/bindings/clock/nvidia,tegra124-car.txt
index ded5d62..2197ffd 100644
--- a/Documentation/devicetree/bindings/clock/nvidia,tegra124-car.txt
+++ b/Documentation/devicetree/bindings/clock/nvidia,tegra124-car.txt
@@ -19,10 +19,31 @@ Required properties :
In clock consumers, this cell represents the bit number in the CAR's
array of CLK_RST_CONTROLLER_RST_DEVICES_* registers.

+The node should contain a "emc-timings" subnode for each supported RAM type (see
+field RAM_CODE in register PMC_STRAPPING_OPT_A).
+
+Required properties for "emc-timings" nodes :
+- nvidia,ram-code : Should contain the value of RAM_CODE this timing set
+ is used for.
+
+Each "emc-timings" node should contain a "timing" subnode for every supported
+EMC clock rate.
+
+Required properties for "timing" nodes :
+- clock-frequency : Should contain the memory clock rate to which this timing
+relates.
+- nvidia,parent-clock-frequency : Should contain the rate at which the current
+parent of the EMC clock should be running at this timing.
+- clocks : Must contain an entry for each entry in clock-names.
+ See ../clocks/clock-bindings.txt for details.
+- clock-names : Must include the following entries:
+ - emc-parent : the clock that should be the parent of the EMC clock at this
+timing.
+
Example SoC include file:

/ {
- tegra_car: clock {
+ tegra_car: clock@60006000 {
compatible = "nvidia,tegra124-car";
reg = <0x60006000 0x1000>;
#clock-cells = <1>;
@@ -60,4 +81,23 @@ Example board file:
&tegra_car {
clocks = <&clk_32k> <&osc>;
};
+
+ clock@60006000 {
+ emc-timings-3 {
+ nvidia,ram-code = <3>;
+
+ timing-12750000 {
+ clock-frequency = <12750000>;
+ nvidia,parent-clock-frequency = <408000000>;
+ clocks = <&tegra_car TEGRA124_CLK_PLL_P>;
+ clock-names = "emc-parent";
+ };
+ timing-20400000 {
+ clock-frequency = <20400000>;
+ nvidia,parent-clock-frequency = <408000000>;
+ clocks = <&tegra_car TEGRA124_CLK_PLL_P>;
+ clock-names = "emc-parent";
+ };
+ };
+ };
};
--
1.9.3