clocksource: ARM sp804: obtain sp804 timer rate via clks

This allows platforms to specify the rate of the SP804 clocksource via
the clk subsystem.  While ARM boards clock these at 1MHz, BCMRing also
has SP804 timers but are clocked at different rates.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 38 insertions, 1 deletions

diff --git a/arch/arm/common/timer-sp.c b/arch/arm/common/timer-sp.c
index f6b9011744a..166f892a24d 100644
--- a/arch/arm/common/timer-sp.c
+++ b/arch/arm/common/timer-sp.c
@@ -18,8 +18,10 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
+#include <linux/clk.h>
 #include <linux/clocksource.h>
 #include <linux/clockchips.h>
+#include <linux/err.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/io.h>
@@ -32,8 +34,43 @@
 #define TIMER_FREQ_KHZ	(1000)
 #define TIMER_RELOAD	(TIMER_FREQ_KHZ * 1000 / HZ)
 
+static long __init sp804_get_clock_rate(const char *name)
+{
+	struct clk *clk;
+	long rate;
+	int err;
+
+	clk = clk_get_sys("sp804", name);
+	if (IS_ERR(clk)) {
+		pr_err("sp804: %s clock not found: %d\n", name,
+			(int)PTR_ERR(clk));
+		return PTR_ERR(clk);
+	}
+
+	err = clk_enable(clk);
+	if (err) {
+		pr_err("sp804: %s clock failed to enable: %d\n", name, err);
+		clk_put(clk);
+		return err;
+	}
+
+	rate = clk_get_rate(clk);
+	if (rate < 0) {
+		pr_err("sp804: %s clock failed to get rate: %ld\n", name, rate);
+		clk_disable(clk);
+		clk_put(clk);
+	}
+
+	return rate;
+}
+
 void __init sp804_clocksource_init(void __iomem *base, const char *name)
 {
+	long rate = sp804_get_clock_rate(name);
+
+	if (rate < 0)
+		return;
+
 	/* setup timer 0 as free-running clocksource */
 	writel(0, base + TIMER_CTRL);
 	writel(0xffffffff, base + TIMER_LOAD);
@@ -42,7 +79,7 @@ void __init sp804_clocksource_init(void __iomem *base, const char *name)
 		base + TIMER_CTRL);
 
 	clocksource_mmio_init(base + TIMER_VALUE, name,
-		TIMER_FREQ_KHZ * 1000, 200, 32, clocksource_mmio_readl_down);
+		rate, 200, 32, clocksource_mmio_readl_down);
 }