clocksource: atmel-st: get and use slow clock
The current slow clock rate is hardcoded. Properly get the slow clock
and use its rate.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
diff --git a/drivers/clocksource/timer-atmel-st.c b/drivers/clocksource/timer-atmel-st.c
index 41b7b6d..29d21d6 100644
--- a/drivers/clocksource/timer-atmel-st.c
+++ b/drivers/clocksource/timer-atmel-st.c
@@ -22,6 +22,7 @@
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
+#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/export.h>
#include <linux/mfd/syscon.h>
@@ -33,9 +34,7 @@
static u32 irqmask;
static struct clock_event_device clkevt;
static struct regmap *regmap_st;
-
-#define AT91_SLOW_CLOCK 32768
-#define RM9200_TIMER_LATCH ((AT91_SLOW_CLOCK + HZ/2) / HZ)
+static int timer_latch;
/*
* The ST_CRTR is updated asynchronously to the master clock ... but
@@ -82,8 +81,8 @@
if (sr & AT91_ST_PITS) {
u32 crtr = read_CRTR();
- while (((crtr - last_crtr) & AT91_ST_CRTV) >= RM9200_TIMER_LATCH) {
- last_crtr += RM9200_TIMER_LATCH;
+ while (((crtr - last_crtr) & AT91_ST_CRTV) >= timer_latch) {
+ last_crtr += timer_latch;
clkevt.event_handler(&clkevt);
}
return IRQ_HANDLED;
@@ -144,7 +143,7 @@
/* PIT for periodic irqs; fixed rate of 1/HZ */
irqmask = AT91_ST_PITS;
- regmap_write(regmap_st, AT91_ST_PIMR, RM9200_TIMER_LATCH);
+ regmap_write(regmap_st, AT91_ST_PIMR, timer_latch);
regmap_write(regmap_st, AT91_ST_IER, irqmask);
return 0;
}
@@ -197,7 +196,8 @@
*/
static void __init atmel_st_timer_init(struct device_node *node)
{
- unsigned int val;
+ struct clk *sclk;
+ unsigned int sclk_rate, val;
int irq, ret;
regmap_st = syscon_node_to_regmap(node);
@@ -221,6 +221,19 @@
if (ret)
panic(pr_fmt("Unable to setup IRQ\n"));
+ sclk = of_clk_get(node, 0);
+ if (IS_ERR(sclk))
+ panic(pr_fmt("Unable to get slow clock\n"));
+
+ clk_prepare_enable(sclk);
+ if (ret)
+ panic(pr_fmt("Could not enable slow clock\n"));
+
+ sclk_rate = clk_get_rate(sclk);
+ if (!sclk_rate)
+ panic(pr_fmt("Invalid slow clock rate\n"));
+ timer_latch = (sclk_rate + HZ / 2) / HZ;
+
/* The 32KiHz "Slow Clock" (tick every 30517.58 nanoseconds) is used
* directly for the clocksource and all clockevents, after adjusting
* its prescaler from the 1 Hz default.
@@ -229,11 +242,11 @@
/* Setup timer clockevent, with minimum of two ticks (important!!) */
clkevt.cpumask = cpumask_of(0);
- clockevents_config_and_register(&clkevt, AT91_SLOW_CLOCK,
+ clockevents_config_and_register(&clkevt, sclk_rate,
2, AT91_ST_ALMV);
/* register clocksource */
- clocksource_register_hz(&clk32k, AT91_SLOW_CLOCK);
+ clocksource_register_hz(&clk32k, sclk_rate);
}
CLOCKSOURCE_OF_DECLARE(atmel_st_timer, "atmel,at91rm9200-st",
atmel_st_timer_init);