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Subject[RFC 3/8] ARM: twd: clock rate from DT (if no DT clk tree)
Date
Add an optional property to find clock-frequency from DT. This helps
as a fallback mechanism in case there is no representation of clock
tree in DT.

Signed-off-by: Afzal Mohammed <afzal@ti.com>
---
Documentation/devicetree/bindings/arm/twd.txt | 7 ++++++-
arch/arm/kernel/smp_twd.c | 8 ++++++++
2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/arm/twd.txt b/Documentation/devicetree/bindings/arm/twd.txt
index 75b8610..fdafa4f 100644
--- a/Documentation/devicetree/bindings/arm/twd.txt
+++ b/Documentation/devicetree/bindings/arm/twd.txt
@@ -7,8 +7,9 @@ and watchdog.
The TWD is usually attached to a GIC to deliver its two per-processor
interrupts.

-** Timer node required properties:
+** Timer node properties:

+Required properties:
- compatible : Should be one of:
"arm,cortex-a9-twd-timer"
"arm,cortex-a5-twd-timer"
@@ -19,12 +20,16 @@ interrupts.
- reg : Specify the base address and the size of the TWD timer
register window.

+Optional property:
+- clock-frequency : frequency(Hz) of peripheral clock fed to timer
+
Example:

twd-timer@2c000600 {
compatible = "arm,arm11mp-twd-timer"";
reg = <0x2c000600 0x20>;
interrupts = <1 13 0xf01>;
+ clock-frequency = <300000000>;
};

** Watchdog node properties:
diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
index 118f4f2..aac0f9f 100644
--- a/arch/arm/kernel/smp_twd.c
+++ b/arch/arm/kernel/smp_twd.c
@@ -247,7 +247,15 @@ static void twd_get_clock(struct device_node *np)
twd_clk = clk_get_sys("smp_twd", NULL);

if (IS_ERR(twd_clk)) {
+ u32 freq;
+
pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk));
+
+ /* If there is no representation of clock tree in DT,
+ provide a fallback option to obtain frequency
+ */
+ if (np && !of_property_read_u32(np, "clock-frequency", &freq))
+ twd_timer_rate = freq;
return;
}

--
1.7.12


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