[ARM] 3991/1: i.MX/MX1 high resolution time source
Enhanced resolution for time measurement functions.
Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mach-imx/time.c b/arch/arm/mach-imx/time.c
index 8ae4a2c5..40039b2 100644
--- a/arch/arm/mach-imx/time.c
+++ b/arch/arm/mach-imx/time.c
@@ -14,6 +14,7 @@
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/time.h>
+#include <linux/clocksource.h>
#include <asm/hardware.h>
#include <asm/io.h>
@@ -24,33 +25,7 @@
/* Use timer 1 as system timer */
#define TIMER_BASE IMX_TIM1_BASE
-/*
- * Returns number of us since last clock interrupt. Note that interrupts
- * will have been disabled by do_gettimeoffset()
- */
-static unsigned long imx_gettimeoffset(void)
-{
- unsigned long ticks;
-
- /*
- * Get the current number of ticks. Note that there is a race
- * condition between us reading the timer and checking for
- * an interrupt. We get around this by ensuring that the
- * counter has not reloaded between our two reads.
- */
- ticks = IMX_TCN(TIMER_BASE);
-
- /*
- * Interrupt pending? If so, we've reloaded once already.
- */
- if (IMX_TSTAT(TIMER_BASE) & TSTAT_COMP)
- ticks += LATCH;
-
- /*
- * Convert the ticks to usecs
- */
- return (1000000 / CLK32) * ticks;
-}
+static unsigned long evt_diff;
/*
* IRQ handler for the timer
@@ -58,14 +33,23 @@
static irqreturn_t
imx_timer_interrupt(int irq, void *dev_id)
{
- write_seqlock(&xtime_lock);
+ uint32_t tstat;
/* clear the interrupt */
- if (IMX_TSTAT(TIMER_BASE))
- IMX_TSTAT(TIMER_BASE) = 0;
+ tstat = IMX_TSTAT(TIMER_BASE);
+ IMX_TSTAT(TIMER_BASE) = 0;
- timer_tick();
- write_sequnlock(&xtime_lock);
+ if (tstat & TSTAT_COMP) {
+ do {
+
+ write_seqlock(&xtime_lock);
+ timer_tick();
+ write_sequnlock(&xtime_lock);
+ IMX_TCMP(TIMER_BASE) += evt_diff;
+
+ } while (unlikely((int32_t)(IMX_TCMP(TIMER_BASE)
+ - IMX_TCN(TIMER_BASE)) < 0));
+ }
return IRQ_HANDLED;
}
@@ -77,9 +61,9 @@
};
/*
- * Set up timer interrupt, and return the current time in seconds.
+ * Set up timer hardware into expected mode and state.
*/
-static void __init imx_timer_init(void)
+static void __init imx_timer_hardware_init(void)
{
/*
* Initialise to a known state (all timers off, and timing reset)
@@ -87,7 +71,38 @@
IMX_TCTL(TIMER_BASE) = 0;
IMX_TPRER(TIMER_BASE) = 0;
IMX_TCMP(TIMER_BASE) = LATCH - 1;
- IMX_TCTL(TIMER_BASE) = TCTL_CLK_32 | TCTL_IRQEN | TCTL_TEN;
+
+ IMX_TCTL(TIMER_BASE) = TCTL_FRR | TCTL_CLK_PCLK1 | TCTL_IRQEN | TCTL_TEN;
+ evt_diff = LATCH;
+}
+
+cycle_t imx_get_cycles(void)
+{
+ return IMX_TCN(TIMER_BASE);
+}
+
+static struct clocksource clocksource_imx = {
+ .name = "imx_timer1",
+ .rating = 200,
+ .read = imx_get_cycles,
+ .mask = 0xFFFFFFFF,
+ .shift = 20,
+ .is_continuous = 1,
+};
+
+static int __init imx_clocksource_init(void)
+{
+ clocksource_imx.mult =
+ clocksource_hz2mult(imx_get_perclk1(), clocksource_imx.shift);
+ clocksource_register(&clocksource_imx);
+
+ return 0;
+}
+
+static void __init imx_timer_init(void)
+{
+ imx_timer_hardware_init();
+ imx_clocksource_init();
/*
* Make irqs happen for the system timer
@@ -97,5 +112,4 @@
struct sys_timer imx_timer = {
.init = imx_timer_init,
- .offset = imx_gettimeoffset,
};