[RESEND PATCH v2 4/6] clocksource: kona: Add basic use of external clock
From: mark.rutland@arm.com (Mark Rutland)
Date: 2013-10-17 14:05:47
Also in:
linux-devicetree, linux-mmc, lkml
On Wed, Oct 16, 2013 at 10:47:08PM +0100, Tim Kryger wrote:
When an clock handle is specified in the device tree, enable it and use it to determine the external clock frequency.
I'd drop handle here and just say "When a clock is specified". This will need a binding document update.
quoted hunk ↗ jump to hunk
Signed-off-by: Tim Kryger <redacted> Reviewed-by: Markus Mayer <redacted> Reviewed-by: Matt Porter <redacted> --- drivers/clocksource/bcm_kona_timer.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-)diff --git a/drivers/clocksource/bcm_kona_timer.c b/drivers/clocksource/bcm_kona_timer.c index 0d7d8c3..fd11f96 100644 --- a/drivers/clocksource/bcm_kona_timer.c +++ b/drivers/clocksource/bcm_kona_timer.c@@ -17,6 +17,7 @@ #include <linux/jiffies.h> #include <linux/clockchips.h> #include <linux/types.h> +#include <linux/clk.h> #include <linux/io.h> #include <asm/mach/time.h>@@ -107,11 +108,18 @@ static const struct of_device_id bcm_timer_ids[] __initconst = { static void __init kona_timers_init(struct device_node *node) { u32 freq; + struct clk *external_clk; - if (!of_property_read_u32(node, "clock-frequency", &freq)) + external_clk = of_clk_get_by_name(node, NULL);
Is there only a single external clock input to the kona timer, or is only one relevant here? Are there any other inputs currently not modelled (e.g. regulators)?
+
+ if (!IS_ERR(external_clk)) {
+ arch_timer_rate = clk_get_rate(external_clk);
+ clk_prepare_enable(external_clk);
+ } else if (!of_property_read_u32(node, "clock-frequency", &freq)) {
arch_timer_rate = freq;
- else
- panic("clock-frequency not set in the .dts file");
+ } else {
+ panic("neither clock-frequency or clocks handle in .dts file");Nit: it's not a handle, it's a phandle+args pair. Why not just "Unable to determine clock frequency"? Do we need to panic here? Might a system have other clocks it could use to continue? Thanks, Mark.