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Date: Sun, 21 Jan 2007 01:01:26 +0100
From: Pavel Pisa <pisa@....felk.cvut.cz>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
Sascha Hauer <s.hauer@...gutronix.de>
Subject: [PATCH query] arm: i.MX/MX1 clock event source
Hello Thomas, Sascha and Ingo
please can you find some time to review next patch
arm: i.MX/MX1 clock event source
which has been sent to you and to the ALKML at 2007-01-13.
http://thread.gmane.org/gmane.linux.ports.arm.kernel/29510/focus=29533
There seems to be some problems, because this patch has not been
accepted to patch-2.6.20-rc5-rt7.patch, but GENERIC_CLOCKEVENTS
are set already for i.MX and this results in a problems to run
RT kernel on this architecture.
config ARCH_IMX
bool "IMX"
+ select GENERIC_TIME
+ select GENERIC_CLOCKEVENTS
Thanks for review and your time
Pavel
-------------------------------------------------------------------------------------
Subject: arm: i.MX/MX1 clock event source
Support clock event source based on i.MX general purpose
timer in free running timer mode.
Signed-off-by: Pavel Pisa <pisa@....felk.cvut.cz>
arch/arm/mach-imx/time.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 92 insertions(+)
Index: linux-2.6.20-rc4/arch/arm/mach-imx/time.c
===================================================================
--- linux-2.6.20-rc4.orig/arch/arm/mach-imx/time.c
+++ linux-2.6.20-rc4/arch/arm/mach-imx/time.c
@@ -15,6 +15,9 @@
#include <linux/irq.h>
#include <linux/time.h>
#include <linux/clocksource.h>
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
+#include <linux/clockchips.h>
+#endif
#include <asm/hardware.h>
#include <asm/io.h>
@@ -25,6 +28,11 @@
/* Use timer 1 as system timer */
#define TIMER_BASE IMX_TIM1_BASE
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
+static struct clock_event_device clockevent_imx;
+static enum clock_event_mode clockevent_mode = CLOCK_EVT_PERIODIC;
+#endif
+
static unsigned long evt_diff;
/*
@@ -42,9 +50,16 @@ imx_timer_interrupt(int irq, void *dev_i
if (tstat & TSTAT_COMP) {
do {
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
+ if (clockevent_imx.event_handler)
+ clockevent_imx.event_handler();
+ if (likely(clockevent_mode != CLOCK_EVT_PERIODIC))
+ break;
+#else
write_seqlock(&xtime_lock);
timer_tick();
write_sequnlock(&xtime_lock);
+#endif
IMX_TCMP(TIMER_BASE) += evt_diff;
} while (unlikely((int32_t)(IMX_TCMP(TIMER_BASE)
@@ -99,11 +114,88 @@ static int __init imx_clocksource_init(v
return 0;
}
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
+
+static void imx_set_next_event(unsigned long evt,
+ struct clock_event_device *unused)
+{
+ evt_diff = evt;
+ IMX_TCMP(TIMER_BASE) = IMX_TCN(TIMER_BASE) + evt;
+}
+
+static void imx_set_mode(enum clock_event_mode mode, struct clock_event_device *evt)
+{
+ unsigned long flags;
+
+ /*
+ * The timer interrupt generation is disabled at least
+ * for enough time to call imx_set_next_event()
+ */
+ local_irq_save(flags);
+ /* Disable interrupt in GPT module */
+ IMX_TCTL(TIMER_BASE) &= ~TCTL_IRQEN;
+ if ((mode != CLOCK_EVT_PERIODIC) || (mode != clockevent_mode)) {
+ /* Set event time into far-far future */
+ IMX_TCMP(TIMER_BASE) = IMX_TCN(TIMER_BASE) - 3;
+ /* Clear pending interrupt */
+ IMX_TSTAT(TIMER_BASE) &= ~TSTAT_COMP;
+ }
+ /* Remember timer mode */
+ clockevent_mode = mode;
+ local_irq_restore(flags);
+
+ switch (mode) {
+ case CLOCK_EVT_PERIODIC:
+ case CLOCK_EVT_ONESHOT:
+ /*
+ * Do not put overhead of interrupt enable/disable into
+ * imx_set_next_event(), the core has about 4 minutes
+ * to call imx_set_next_event() or shutdown clock after
+ * mode switching
+ */
+ local_irq_save(flags);
+ IMX_TCTL(TIMER_BASE) |= TCTL_IRQEN;
+ local_irq_restore(flags);
+ break;
+ case CLOCK_EVT_SHUTDOWN:
+ /* Left event sources disabled, no more interrupts appears */
+ break;
+ }
+}
+
+static struct clock_event_device clockevent_imx = {
+ .name = "imx_timer1",
+ .capabilities = CLOCK_CAP_NEXTEVT | CLOCK_CAP_TICK |
+ CLOCK_CAP_UPDATE | CLOCK_CAP_PROFILE,
+ .shift = 32,
+ .set_mode = imx_set_mode,
+ .set_next_event = imx_set_next_event,
+};
+
+static int __init imx_clockevent_init(void)
+{
+ clockevent_imx.mult = div_sc(imx_get_perclk1(), NSEC_PER_SEC,
+ clockevent_imx.shift);
+ clockevent_imx.max_delta_ns =
+ clockevent_delta2ns(0xfffffffe, &clockevent_imx);
+ clockevent_imx.min_delta_ns =
+ clockevent_delta2ns(0xf, &clockevent_imx);
+ register_local_clockevent(&clockevent_imx);
+
+ return 0;
+}
+#endif
+
+
static void __init imx_timer_init(void)
{
imx_timer_hardware_init();
imx_clocksource_init();
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
+ imx_clockevent_init();
+#endif
+
/*
* Make irqs happen for the system timer
*/
-
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