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Subject[PATCH] clocksource: sh_tmu: __clocksource_updatefreq_hz() update
From: Magnus Damm <damm@opensource.se>

This patch updates the clocksource part of the TMU driver
to make use of the __clocksource_updatefreq_hz() function.

Without this patch the old code uses clocksource_register()
together with a hack that assumes a never changing clock rate
(see clk_enable(), clk_get_rate() and clk_disable()).

The patch uses clocksource_register_hz() with 1 Hz as initial
value, then lets the ->enable() callback update the value
with __clocksource_updatefreq_hz() once the struct clk has
been enabled and the frequency is stable.

Signed-off-by: Magnus Damm <damm@opensource.se>
---

Thanks to John Stultz for the framework changes and the
initial implementation.

Tested on the sh7372 Mackerel board with TMU00 and TMU01.

drivers/clocksource/sh_tmu.c | 19 ++++++++-----------
1 file changed, 8 insertions(+), 11 deletions(-)

--- 0001/drivers/clocksource/sh_tmu.c
+++ work/drivers/clocksource/sh_tmu.c 2011-04-25 15:07:41.000000000 +0900
@@ -199,8 +199,12 @@ static cycle_t sh_tmu_clocksource_read(s
static int sh_tmu_clocksource_enable(struct clocksource *cs)
{
struct sh_tmu_priv *p = cs_to_sh_tmu(cs);
+ int ret;

- return sh_tmu_enable(p);
+ ret = sh_tmu_enable(p);
+ if (!ret)
+ __clocksource_updatefreq_hz(cs, p->rate);
+ return ret;
}

static void sh_tmu_clocksource_disable(struct clocksource *cs)
@@ -221,17 +225,10 @@ static int sh_tmu_register_clocksource(s
cs->mask = CLOCKSOURCE_MASK(32);
cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;

- /* clk_get_rate() needs an enabled clock */
- clk_enable(p->clk);
- /* channel will be configured at parent clock / 4 */
- p->rate = clk_get_rate(p->clk) / 4;
- clk_disable(p->clk);
- /* TODO: calculate good shift from rate and counter bit width */
- cs->shift = 10;
- cs->mult = clocksource_hz2mult(p->rate, cs->shift);
-
dev_info(&p->pdev->dev, "used as clock source\n");
- clocksource_register(cs);
+
+ /* Register with dummy 1 Hz value, gets updated in ->enable() */
+ clocksource_register_hz(cs, 1);
return 0;
}


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