clocksource: em_sti: Compute rate before registration

With the upcoming NTP correction related rate adjustments to be implemented
in the clockevents core, the latter needs to get informed about every rate
change of a clockevent device made after its registration.

Currently, em_sti violates this requirement in that it registers its
clockevent device with a dummy rate and sets its final rate through
clockevents_config() called from its ->set_state_oneshot().

This patch moves the setting of the clockevent device's rate to its
registration.

I checked all current em_sti users in arch/arm/mach-shmobile and right now,
none of them changes any rate in any clock tree relevant to em_sti after
their respective time_init(). Since all em_sti instances are created after
time_init(), none of them should ever observe any clock rate changes.

- Determine the ->rate value in em_sti_probe() at device probing rather
  than at first usage.
- Set the clockevent device's rate at its registration.
- Although not strictly necessary for the upcoming clockevent core changes,
  set the clocksource's rate at its registration for consistency.

Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

diff --git a/drivers/clocksource/em_sti.c b/drivers/clocksource/em_sti.c
index 6c0955a92f2478f9da58c20d8c8f93f08c22e9a3..bc48cbf6a7957198d4ecd6bf91840df350843d48 100644 (file)
--- a/drivers/clocksource/em_sti.c
+++ b/drivers/clocksource/em_sti.c
@@ -84,9 +84,6 @@ static int em_sti_enable(struct em_sti_priv *p)
                return ret;
        }
 
-       /* configure channel, periodic mode and maximum timeout */
-       p->rate = clk_get_rate(p->clk);
-
        /* reset the counter */
        em_sti_write(p, STI_SET_H, 0x40000000);
        em_sti_write(p, STI_SET_L, 0x00000000);
@@ -205,13 +202,9 @@ static u64 em_sti_clocksource_read(struct clocksource *cs)
 
 static int em_sti_clocksource_enable(struct clocksource *cs)
 {
-       int ret;
        struct em_sti_priv *p = cs_to_em_sti(cs);
 
-       ret = em_sti_start(p, USER_CLOCKSOURCE);
-       if (!ret)
-               __clocksource_update_freq_hz(cs, p->rate);
-       return ret;
+       return em_sti_start(p, USER_CLOCKSOURCE);
 }
 
 static void em_sti_clocksource_disable(struct clocksource *cs)
@@ -240,8 +233,7 @@ static int em_sti_register_clocksource(struct em_sti_priv *p)
 
        dev_info(&p->pdev->dev, "used as clock source\n");
 
-       /* Register with dummy 1 Hz value, gets updated in ->enable() */
-       clocksource_register_hz(cs, 1);
+       clocksource_register_hz(cs, p->rate);
        return 0;
 }
 
@@ -263,7 +255,6 @@ static int em_sti_clock_event_set_oneshot(struct clock_event_device *ced)
 
        dev_info(&p->pdev->dev, "used for oneshot clock events\n");
        em_sti_start(p, USER_CLOCKEVENT);
-       clockevents_config(&p->ced, p->rate);
        return 0;
 }
 
@@ -294,8 +285,7 @@ static void em_sti_register_clockevent(struct em_sti_priv *p)
 
        dev_info(&p->pdev->dev, "used for clock events\n");
 
-       /* Register with dummy 1 Hz value, gets updated in ->set_state_oneshot() */
-       clockevents_config_and_register(ced, 1, 2, 0xffffffff);
+       clockevents_config_and_register(ced, p->rate, 2, 0xffffffff);
 }
 
 static int em_sti_probe(struct platform_device *pdev)
@@ -344,6 +334,15 @@ static int em_sti_probe(struct platform_device *pdev)
                return ret;
        }
 
+       ret = clk_enable(p->clk);
+       if (ret < 0) {
+               dev_err(&p->pdev->dev, "cannot enable clock\n");
+               clk_unprepare(p->clk);
+               return ret;
+       }
+       p->rate = clk_get_rate(p->clk);
+       clk_disable(p->clk);
+
        raw_spin_lock_init(&p->lock);
        em_sti_register_clockevent(p);
        em_sti_register_clocksource(p);