clocksource: sh_cmt: compute mult and shift before registration

Based on the sh_tmu change in 66f49121ffa41a19c59965b31b046d8368fec3c7
("clocksource: sh_tmu: compute mult and shift before registration").
The same issues impact the sh_cmt driver, so we take the same approach
here.

Cc: stable@kernel.org
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 13 insertions, 9 deletions

diff --git a/drivers/clocksource/sh_cmt.c b/drivers/clocksource/sh_cmt.c
index f6677cb..f3d3898 100644
--- a/drivers/clocksource/sh_cmt.c
+++ b/drivers/clocksource/sh_cmt.c
@@ -412,18 +412,10 @@ static cycle_t sh_cmt_clocksource_read(struct clocksource *cs)
 static int sh_cmt_clocksource_enable(struct clocksource *cs)
 {
 	struct sh_cmt_priv *p = cs_to_sh_cmt(cs);
-	int ret;
 
 	p->total_cycles = 0;
 
-	ret = sh_cmt_start(p, FLAG_CLOCKSOURCE);
-	if (ret)
-		return ret;
-
-	/* TODO: calculate good shift from rate and counter bit width */
-	cs->shift = 0;
-	cs->mult = clocksource_hz2mult(p->rate, cs->shift);
-	return 0;
+	return sh_cmt_start(p, FLAG_CLOCKSOURCE);
 }
 
 static void sh_cmt_clocksource_disable(struct clocksource *cs)
@@ -450,8 +442,20 @@ static int sh_cmt_register_clocksource(struct sh_cmt_priv *p,
 	cs->resume = sh_cmt_clocksource_resume;
 	cs->mask = CLOCKSOURCE_MASK(sizeof(unsigned long) * 8);
 	cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
+
+	/* clk_get_rate() needs an enabled clock */
+	clk_enable(p->clk);
+	p->rate = clk_get_rate(p->clk) / (p->width == 16) ? 512 : 8;
+	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);
+
 	return 0;
 }