* Giuseppe CAVALLARO ([email protected]) wrote:
> LTTng trace clock definitions for SuperH were broken for the new Kernels.
> The patch reviews this code using the clocksource API to handle trace clock.
> For example, on ST Kernels the TMU channel 1 continues to be used as
> clocksource and all works fine for LTT (tested on SH4 STM platforms based).
> Concerning the TMU frequency, it comes from the module_clk clock available
> on SuperH platforms.
>
> Signed-off-by: Giuseppe Cavallaro <[email protected]>
> ---
> arch/sh/include/asm/trace-clock.h | 26 ++++++++++++++++++++------
> 1 files changed, 20 insertions(+), 6 deletions(-)
>
> diff --git a/arch/sh/include/asm/trace-clock.h
> b/arch/sh/include/asm/trace-clock.h
> index 7dfa042..14a00e2 100644
> --- a/arch/sh/include/asm/trace-clock.h
> +++ b/arch/sh/include/asm/trace-clock.h
> @@ -8,7 +8,7 @@
> #ifndef _ASM_SH_TRACE_CLOCK_H
> #define _ASM_SH_TRACE_CLOCK_H
>
> -#include <linux/timer.h>
> +#include <linux/clocksource.h>
> #include <asm/clock.h>
>
> /*
> @@ -23,11 +23,18 @@
> /* Expected maximum interrupt latency in ms : 15ms, *2 for security */
> #define TC_EXPECTED_INTERRUPT_LATENCY 30
>
> +static struct clocksource *clksrc;
static definitions in headers are prohibited by the kernel coding style.
You will probably need to create a trace-clock.c with a proper "init"
function.
> +
> extern u64 trace_clock_read_synthetic_tsc(void);
>
> static inline u32 trace_clock_read32(void)
> {
> - return get_cycles();
> + u32 value = 0;
> +
> + if (likely(clksrc))
> + value = (u32) clksrc->read(clksrc);
> +
> + return value;
> }
>
> static inline u64 trace_clock_read64(void)
> @@ -37,11 +44,18 @@ static inline u64 trace_clock_read64(void)
>
> static inline u64 trace_clock_frequency(void)
> {
> - u64 rate;
> - struct clk *tmu1_clk;
> + u64 rate = 0;
> + struct clk *clk;
> +
> + /* Get the Clock rate for the TMU channels */
> + clk = clk_get(NULL, "module_clk");
> + if (likely(clk))
> + rate = clk_get_rate(clk) / 4;
>
> - tmu1_clk = clk_get(NULL, "tmu1_clk");
> - rate = clk_get_rate(tmu1_clk);
> + /* Get the clocksource needed to read the timer counter register */
How can you be sure that this will select the sh_tmu_clocksource_read
clocksource ? (even in future kernel versions ?)
Thanks,
Mathieu
> + clksrc = clocksource_get_next();
> + if (unlikely(!clksrc))
> + pr_err("%s: no clocksource found\n", __func__);
>
> return rate;
> }
> --
> 1.6.0.4
>
>
> _______________________________________________
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>
--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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