clocksource: dw_apb_timer_of: add clock-handling
From: Heiko Stuebner <heiko@...> Date: Tue, 28 May 2013 19:41:02 +0200
Commit-Message
Add the possibility to get the clock-frequency from a timer clock instead of specifying it as dt property. Additionally also add the possibility to also define a controlling periphal clock for the timer block. The clock-frequency property is kept to act as fallback if no clocks are specified. Signed-off-by: Heiko Stuebner <heiko@...>
Patch-Comment
Documentation/devicetree/bindings/rtc/dw-apb.txt | 19 ++++++++++++++++ drivers/clocksource/dw_apb_timer_of.c | 26 +++++++++++++++++++++- 2 files changed, 44 insertions(+), 1 deletions(-)
Statistics
- 44 lines added
- 1 lines removed
Changes
--------------- Documentation/devicetree/bindings/rtc/dw-apb.txt ---------------
index 93e2b0f..80ab1c1 100644
@@ -5,9 +5,20 @@ Required properties:
- reg: physical base address of the controller and length of memory mapped
region.
- interrupts: IRQ line for the timer.
+- either clocks+clock-names or clock-frequency properties
+
+Optional properties:
+- clocks : list of clock specifiers, corresponding to entries in
+ the clock-names property;
+- clock-names : should contain "timer and "pclk" entries, matching entries
+ in the clocks property.
- clock-frequency: The frequency in HZ of the timer.
- clock-freq: For backwards compatibility with picoxcell
+If using the clock specifiers, the pclk clock is optional, as not all
+systems may use one.
+
+
Example:
timer1: timer@ffc09000 {
@@ -23,3 +34,11 @@ Example:
clock-frequency = <200000000>;
reg = <0xffd00000 0x1000>;
};
+
+ timer3: timer@ffe00000 {
+ compatible = "snps,dw-apb-timer-osc";
+ interrupts = <0 170 4>;
+ reg = <0xffe00000 0x1000>;
+ clocks = <&timer_clk>, <&timer_pclk>;
+ clock-names = "timer", "pclk";
+ };
-------------------- drivers/clocksource/dw_apb_timer_of.c ---------------------
index d6c0fda..1964f87 100644
@@ -20,6 +20,7 @@
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
+#include <linux/clk.h>
#include <asm/mach/time.h>
#include <asm/sched_clock.h>
@@ -27,14 +28,37 @@
static void timer_get_base_and_rate(struct device_node *np,
void __iomem **base, u32 *rate)
{
+ struct clk *timer_clk;
+ struct clk *pclk;
+
*base = of_iomap(np, 0);
if (!*base)
panic("Unable to map regs for %s", np->name);
+ /*
+ * Not all implementations use a periphal clock, so don't panic
+ * if it's not present
+ */
+ pclk = of_clk_get_by_name(np, "pclk");
+ if (!IS_ERR(pclk))
+ if (clk_prepare_enable(pclk))
+ pr_warn("pclk for %s is present, but could not be activated\n",
+ np->name);
+
+ timer_clk = of_clk_get_by_name(np, "timer");
+ if (IS_ERR(timer_clk))
+ goto try_clock_freq;
+
+ if (!clk_prepare_enable(timer_clk)) {
+ *rate = clk_get_rate(timer_clk);
+ return;
+ }
+
+try_clock_freq:
if (of_property_read_u32(np, "clock-freq", rate) &&
of_property_read_u32(np, "clock-frequency", rate))
+ panic("No clock nor clock-frequency property for %s", np->name);
}
static void add_clockevent(struct device_node *event_timer)