On Wednesday 09 January 2013 11:27 AM, Hiroshi Doyu wrote:
Hi Marc,
Marc Zyngier <marc.zyngier@xxxxxxx> wrote @ Tue, 8 Jan 2013 17:07:39 +0100:
On 08/01/13 12:47, Hiroshi Doyu wrote:
Add platform enabler for ARM arch_timer(TSC). TSC is more fine grained
timer than TMR0. If it's available, it will be used for clock source
and sched_clock. Otherwise, TMR0 is used. In any case TMR0 is
necessary for clock event.
Signed-off-by: Hiroshi Doyu <hdoyu@xxxxxxxxxx>
---
.../bindings/arm/tegra/nvidia,tegra114-tsc.txt | 11 ++++
drivers/clocksource/tegra20_timer.c | 65 +++++++++++++++++++-
2 files changed, 75 insertions(+), 1 deletion(-)
create mode 100644 Documentation/devicetree/bindings/arm/tegra/nvidia,tegra114-tsc.txt
diff --git a/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra114-tsc.txt b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra114-tsc.txt
new file mode 100644
index 0000000..9de936a
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra114-tsc.txt
@@ -0,0 +1,11 @@
+NVIDIA Tegra Timer Stamp Counter(TSC)
+
+Required properties:
+- compatible : "nvidia,tegra114-tsc
+- reg : Should contain 1 register ranges(address and length)
+
+Example:
+ tsc {
+ compatible = "nvidia,tegra114-tsc";
+ reg = <0x700f0000 0x20000>;
+ };
diff --git a/drivers/clocksource/tegra20_timer.c b/drivers/clocksource/tegra20_timer.c
index 1d25de8..564266d 100644
--- a/drivers/clocksource/tegra20_timer.c
+++ b/drivers/clocksource/tegra20_timer.c
@@ -30,6 +30,7 @@
#include <asm/mach/time.h>
#include <asm/smp_twd.h>
#include <asm/sched_clock.h>
+#include <asm/arch_timer.h>
#define RTC_SECONDS 0x08
#define RTC_SHADOW_SECONDS 0x0c
@@ -271,10 +272,72 @@ static void __init tegra20_init_tmr(void)
clockevents_register_device(&tegra_clockevent);
}
+#define TSC_CNTCR 0 /* TSC control registers */
+#define TSC_CNTCR_ENABLE (1 << 0) /* Enable */
+#define TSC_CNTCR_HDBG (1 << 1) /* Halt on debug */
+
+#define TSC_CNTCV0 0x8 /* TSC counter (LSW) */
+#define TSC_CNTCV1 0xc /* TSC counter (MSW) */
+#define TSC_CNTFID0 0x20 /* TSC freq id 0 */
+
+static const struct of_device_id tegra_tsc_match[] __initconst = {
+ { .compatible = "nvidia,tegra114-tsc" },
+ {}
+};
+
+/* FIXME: only secure mode is supported. */
And this is a bug, as far as I'm concerned.
+static int tegra_arch_timer_init(void)
+{
+ int err;
+ struct device_node *np;
+ struct clk *clk;
+ void __iomem *tsc_base;
+ u32 freq, val;
+
+ np = of_find_matching_node(NULL, tegra_tsc_match);
+ if (!np)
+ return -ENODEV;
+
+ tsc_base = of_iomap(np, 0);
+ if (!tsc_base)
+ return -ENODEV;
+
+ clk = clk_get_sys("clk_m", NULL);
+ if (IS_ERR(clk)) {
+ freq = 12000000;
+ pr_warn("Unable to get timer clock. Assuming 12Mhz input clock.\n");
+ } else {
+ freq = clk_get_rate(clk);
+ clk_put(clk);
+ }
+ writel_relaxed(freq, tsc_base + TSC_CNTFID0);
+
+ /* CNTFRQ */
+ asm("mcr p15, 0, %0, c14, c0, 0\n" : : "r" (freq));
+ asm("mrc p15, 0, %0, c14, c0, 0\n" : "=r" (val));
+ BUG_ON(val != freq);
No, not again! Like I said last year, this won't fly. So instead of
trying to work around a broken firmware, let's do the right thing.
+
+ val = readl_relaxed(tsc_base + TSC_CNTCR);
+ val |= TSC_CNTCR_ENABLE | TSC_CNTCR_HDBG;
+ writel_relaxed(val, tsc_base + TSC_CNTCR);
+
+ err = arch_timer_of_register();
What about adding an optional property to the binding, pointing to the
required clock? That would solve the above problem in a sensible way,
and your kernel wouldn't go bust.
Could you explain a bit more? We have the follwing DT entries related to this:
tsc {
compatible = "nvidia,tegra114-tsc";
reg = <0x700f0000 0x20000>;
};
...
timer {
compatible = "arm,armv7-timer";
interrupts = <1 13 0xf08>,
<1 14 0xf08>,
<1 11 0xf08>,
<1 10 0xf08>;
};
Arch timer frequency can be specified in DT since the code
already has provision to extract it. Below is extract
from OMAP5 DT code.
timer {
compatible = "arm,armv7-timer";
interrupts = <1 14 0x308>;
clock-frequency = <6144000>;
};
I think thats what Marc is pointing out.
Regards
Santosh
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