Re: [Xenomai-core] Xenomai on PXA

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

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Bart Jonkers wrote:
 > On Wed, 2006-08-02 at 15:09 +0200, Gilles Chanteperdrix wrote:
 > > Detlef Vollmann wrote:
 > >  > > I also added an interrupt handler on a button which is connected to GPIO
 > >  > > pin. The interrupt handler should print something when it is executed.
 > >  > > When I push the button a couple of times nothing happens. So GPIO
 > >  > > interrupts doesn't seems to work.
 > >  > Probably GPIO0 and GPIO1 work.
 > >  > I suspect it's the cascading interrupt that doesn't work.
 > >  > When I played around with an earlier version of ipipe, I found that
 > >  > the IRQ_GPIO_2_80 (IRQ 10 on PXA270) is masked, but never unmasked
 > >  > again.
 > >  > 
 > >  > The problem is that for the cascading interrupt you need a special
 > >  > IPIPE handler, and I don't think there is currently one for PXA.
 > >  > 
 > >  > How is that done on other machines/architectures?
 > > 
 > > When looking at the ipipe_enable_pipeline function, we see that
 > > interrupts management routines are all intercepted by the I-pipe, so the
 > > cascaded interrupts management routines should be automatically
 > > intercepted. 
 > > 
 > > In order to have a better understanding of the issue, it would be
 > > interesting if you could trace the functions that are called on the path
 > > from the interrupt to the execution of the final handler.
 > 
 > I have tracked and solved the issue. I have looked to the i.MX21 port
 > and they added some code to the GPIO interrupt handler of the i.MX21.
 > When IPIPE is active they unmask the interrupt for the GPIO pins at the
 > end of the handler. I did the same for PXA and my GPIO interrupt problem
 > is solved. I think that the same is needed for SA-1100.

Here is a new version of the ipipe-sa1100-pxa patch that unmaks
interrupts at the end of the demux handlers, and that attempt to fix the
gettimeoffset issue. I have run 20 minutes (time for OSCR to wrap) latency
with a test program verifying that time returned by gettimeofday is
never going backward.

The patch and the test program are attached, it would be nice if you
could test them.

-- 


					    Gilles Chanteperdrix.

[-- Attachment #2: ipipe-sa1100-pxa.2.patch --]
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--- linux-2.6.16.5-tcl1/arch/arm/mach-pxa/irq.c	2005-10-28 02:02:08.000000000 +0200
+++ linux-2.6.16.5-tcl1-ipipe/arch/arm/mach-pxa/irq.c	2006-08-02 17:57:30.000000000 +0200
@@ -143,6 +143,10 @@ static struct irqchip pxa_low_gpio_chip 
 static void pxa_gpio_demux_handler(unsigned int irq, struct irqdesc *desc,
 				   struct pt_regs *regs)
 {
+#ifdef CONFIG_IPIPE
+	struct irqdesc *desc_unused = desc;
+	unsigned irq_unused = irq;
+#endif /* CONFIG_IPIPE */
 	unsigned int mask;
 	int loop;
 
@@ -212,6 +216,10 @@ static void pxa_gpio_demux_handler(unsig
 		}
 #endif
 	} while (loop);
+
+#ifdef CONFIG_IPIPE
+	desc_unused->chip->unmask(irq_unused);
+#endif /* CONFIG_IPIPE */
 }
 
 static void pxa_ack_muxed_gpio(unsigned int irq)
--- linux-2.6.16.5-tcl1/arch/arm/mach-pxa/time.c	2006-05-07 15:36:35.000000000 +0200
+++ linux-2.6.16.5-tcl1-ipipe/arch/arm/mach-pxa/time.c	2006-08-02 19:17:30.000000000 +0200
@@ -19,6 +19,7 @@
 #include <linux/signal.h>
 #include <linux/errno.h>
 #include <linux/sched.h>
+#include <linux/module.h>
 
 #include <asm/system.h>
 #include <asm/hardware.h>
@@ -30,6 +31,23 @@
 #include <asm/arch/pxa-regs.h>
 
 
+#ifdef CONFIG_IPIPE
+#ifdef CONFIG_NO_IDLE_HZ
+#error "dynamic tick timer not yet supported with IPIPE"
+#endif /* CONFIG_NO_IDLE_HZ */
+int __ipipe_mach_timerint = IRQ_OST0;
+EXPORT_SYMBOL(__ipipe_mach_timerint);
+
+int __ipipe_mach_timerstolen = 0;
+EXPORT_SYMBOL(__ipipe_mach_timerstolen);
+
+unsigned int __ipipe_mach_ticks_per_jiffy = LATCH;
+EXPORT_SYMBOL(__ipipe_mach_ticks_per_jiffy);
+
+static int pxa_timer_initialized;
+static unsigned long pxa_jiffies;
+#endif /* CONFIG_IPIPE */
+
 static inline unsigned long pxa_get_rtc_time(void)
 {
 	return RCNR;
@@ -54,6 +72,9 @@ static unsigned long pxa_gettimeoffset (
 {
 	long ticks_to_match, elapsed, usec;
 
+#ifdef CONFIG_IPIPE
+	if (!__ipipe_mach_timerstolen) {
+#endif
 	/* Get ticks before next timer match */
 	ticks_to_match = OSMR0 - OSCR;
 
@@ -63,6 +84,10 @@ static unsigned long pxa_gettimeoffset (
 	/* don't get fooled by the workaround in pxa_timer_interrupt() */
 	if (elapsed <= 0)
 		return 0;
+#ifdef CONFIG_IPIPE
+	} else
+		elapsed = OSCR - pxa_jiffies * LATCH;
+#endif
 
 	/* Now convert them to usec */
 	usec = (unsigned long)(elapsed * (tick_nsec / 1000))/LATCH;
@@ -105,9 +130,27 @@ pxa_timer_interrupt(int irq, void *dev_i
 	 * affect things only when the timer IRQ has been delayed by nearly
 	 * exactly one tick period which should be a pretty rare event.
 	 */
+#ifdef CONFIG_IPIPE
+	/*
+	 * - if Linux is running natively (no ipipe), ack and reprogram the timer
+	 * - if Linux is running under ipipe, but it still has the control over
+	 *   the timer (no Xenomai for example), then reprogram the timer (ipipe
+	 *   has already acked it)
+	 * - if some other domain has taken over the timer, then do nothing
+	 *   (ipipe has acked it, and the other domain has reprogramed it)
+	 */
+	if (__ipipe_mach_timerstolen) {
+		timer_tick(regs);
+		++pxa_jiffies;
+	} else
+#endif /* CONFIG_IPIPE */
 	do {
 		timer_tick(regs);
+#ifdef CONFIG_IPIPE
+		++pxa_jiffies;
+#else /* !CONFIG_IPIPE */
 		OSSR = OSSR_M0;  /* Clear match on timer 0 */
+#endif /* !CONFIG_IPIPE */
 		next_match = (OSMR0 += LATCH);
 	} while( (signed long)(next_match - OSCR) <= 8 );
 
@@ -139,6 +182,10 @@ static void __init pxa_timer_init(void)
 	setup_irq(IRQ_OST0, &pxa_timer_irq);
 	OIER = OIER_E0;		/* enable match on timer 0 to cause interrupts */
 	OSCR = 0;		/* initialize free-running timer */
+
+#ifdef CONFIG_IPIPE
+	pxa_timer_initialized = 1;
+#endif /* CONFIG_IPIPE */
 }
 
 #ifdef CONFIG_NO_IDLE_HZ
@@ -216,3 +263,69 @@ struct sys_timer pxa_timer = {
 	.dyn_tick	= &pxa_dyn_tick,
 #endif
 };
+
+#ifdef CONFIG_IPIPE
+void __ipipe_mach_acktimer(void)
+{
+	OSSR = OSSR_M0;  /* Clear match on timer 0 */
+}
+
+unsigned long long __ipipe_mach_get_tsc(void)
+{
+	if (likely(pxa_timer_initialized)) {
+		static union {
+#ifdef __BIG_ENDIAN
+			struct {
+				unsigned long high;
+				unsigned long low;
+			};
+#else /* __LITTLE_ENDIAN */
+			struct {
+				unsigned long low;
+				unsigned long high;
+			};
+#endif /* __LITTLE_ENDIAN */
+			unsigned long long full;
+		} tsc[NR_CPUS], *local_tsc;
+		unsigned long stamp, flags;
+		unsigned long long result;
+
+		local_irq_save_hw(flags);
+		local_tsc = &tsc[ipipe_processor_id()];
+		stamp = OSCR;
+		if (unlikely(stamp < local_tsc->low))
+			/* 32 bit counter wrapped, increment high word. */
+			local_tsc->high++;
+		local_tsc->low = stamp;
+		result = local_tsc->full;
+		local_irq_restore_hw(flags);
+
+		return result;
+	}
+	
+        return 0;
+}
+EXPORT_SYMBOL(__ipipe_mach_get_tsc);
+
+/*
+ * Reprogram the timer
+ */
+
+void __ipipe_mach_set_dec(unsigned long delay)
+{
+	if (delay > 8) {
+		unsigned long flags;
+
+		local_irq_save_hw(flags);
+		OSMR0 = delay + OSCR;
+		local_irq_restore_hw(flags);
+	} else
+		ipipe_trigger_irq(IRQ_OST0);
+}
+EXPORT_SYMBOL(__ipipe_mach_set_dec);
+
+unsigned long __ipipe_mach_get_dec(void)
+{
+	return OSMR0 - OSCR;
+}
+#endif /* CONFIG_IPIPE */
--- linux-2.6.16.5-tcl1/arch/arm/mach-sa1100/irq.c	2005-10-28 02:02:08.000000000 +0200
+++ linux-2.6.16.5-tcl1-ipipe/arch/arm/mach-sa1100/irq.c	2006-08-02 17:55:48.000000000 +0200
@@ -111,6 +111,10 @@ static void
 sa1100_high_gpio_handler(unsigned int irq, struct irqdesc *desc,
 			 struct pt_regs *regs)
 {
+#ifdef CONFIG_IPIPE
+	struct irqdesc *desc_unused = desc;
+	unsigned irq_unused = irq;
+#endif /* CONFIG_IPIPE */
 	unsigned int mask;
 
 	mask = GEDR & 0xfffff800;
@@ -134,6 +138,10 @@ sa1100_high_gpio_handler(unsigned int ir
 
 		mask = GEDR & 0xfffff800;
 	} while (mask);
+
+#ifdef CONFIG_IPIPE
+	desc_unused->chip->unmask(irq_unused);
+#endif /* CONFIG_IPIPE */
 }
 
 /*
--- linux-2.6.16.5-tcl1/arch/arm/mach-sa1100/time.c	2006-05-07 15:36:35.000000000 +0200
+++ linux-2.6.16.5-tcl1-ipipe/arch/arm/mach-sa1100/time.c	2006-08-02 19:09:06.000000000 +0200
@@ -13,6 +13,7 @@
 #include <linux/interrupt.h>
 #include <linux/timex.h>
 #include <linux/signal.h>
+#include <linux/module.h>
 
 #include <asm/mach/time.h>
 #include <asm/hardware.h>
@@ -20,6 +21,23 @@
 #define RTC_DEF_DIVIDER		(32768 - 1)
 #define RTC_DEF_TRIM            0
 
+#ifdef CONFIG_IPIPE
+#ifdef CONFIG_NO_IDLE_HZ
+#error "dynamic tick timer not yet supported with IPIPE"
+#endif /* CONFIG_NO_IDLE_HZ */
+int __ipipe_mach_timerint = IRQ_OST0;
+EXPORT_SYMBOL(__ipipe_mach_timerint);
+
+int __ipipe_mach_timerstolen = 0;
+EXPORT_SYMBOL(__ipipe_mach_timerstolen);
+
+unsigned int __ipipe_mach_ticks_per_jiffy = LATCH;
+EXPORT_SYMBOL(__ipipe_mach_ticks_per_jiffy);
+
+static int sa1100_timer_initialized;
+static unsigned long sa1100_jiffies;
+#endif /* CONFIG_IPIPE */
+
 static unsigned long __init sa1100_get_rtc_time(void)
 {
 	/*
@@ -58,11 +76,18 @@ static unsigned long sa1100_gettimeoffse
 {
 	unsigned long ticks_to_match, elapsed, usec;
 
+#ifdef CONFIG_IPIPE
+	if (!__ipipe_mach_timerstolen) {
+#endif
 	/* Get ticks before next timer match */
 	ticks_to_match = OSMR0 - OSCR;
 
 	/* We need elapsed ticks since last match */
 	elapsed = LATCH - ticks_to_match;
+#ifdef CONFIG_IPIPE
+	} else
+		elapsed = OSCR - sa1100_jiffies * LATCH;
+#endif
 
 	/* Now convert them to usec */
 	usec = (unsigned long)(elapsed * (tick_nsec / 1000))/LATCH;
@@ -97,9 +122,27 @@ sa1100_timer_interrupt(int irq, void *de
 	 * ensured, hence we can use do_gettimeofday() from interrupt
 	 * handlers.
 	 */
+#ifdef CONFIG_IPIPE
+	/*
+	 * - if Linux is running natively (no ipipe), ack and reprogram the timer
+	 * - if Linux is running under ipipe, but it still has the control over
+	 *   the timer (no Xenomai for example), then reprogram the timer (ipipe
+	 *   has already acked it)
+	 * - if some other domain has taken over the timer, then do nothing
+	 *   (ipipe has acked it, and the other domain has reprogramed it)
+	 */
+	if (__ipipe_mach_timerstolen) {
+		timer_tick(regs);
+		++sa1100_jiffies;
+	} else
+#endif /* CONFIG_IPIPE */
 	do {
 		timer_tick(regs);
+#ifdef CONFIG_IPIPE
+		++sa1100_jiffies;
+#else /* !CONFIG_IPIPE */
 		OSSR = OSSR_M0;  /* Clear match on timer 0 */
+#endif /* !CONFIG_IPIPE */
 		next_match = (OSMR0 += LATCH);
 	} while ((signed long)(next_match - OSCR) <= 0);
 
@@ -131,6 +174,10 @@ static void __init sa1100_timer_init(voi
 	setup_irq(IRQ_OST0, &sa1100_timer_irq);
 	OIER = OIER_E0;		/* enable match on timer 0 to cause interrupts */
 	OSCR = 0;		/* initialize free-running timer */
+
+#ifdef CONFIG_IPIPE
+	sa1100_timer_initialized = 1;
+#endif /* CONFIG_IPIPE */
 }
 
 #ifdef CONFIG_NO_IDLE_HZ
@@ -209,3 +256,66 @@ struct sys_timer sa1100_timer = {
 	.dyn_tick	= &sa1100_dyn_tick,
 #endif
 };
+
+#ifdef CONFIG_IPIPE
+void __ipipe_mach_acktimer(void)
+{
+	OSSR = OSSR_M0;  /* Clear match on timer 0 */
+}
+
+unsigned long long __ipipe_mach_get_tsc(void)
+{
+	if (likely(sa1100_timer_initialized)) {
+		static union {
+#ifdef __BIG_ENDIAN
+			struct {
+				unsigned long high;
+				unsigned long low;
+			};
+#else /* __LITTLE_ENDIAN */
+			struct {
+				unsigned long low;
+				unsigned long high;
+			};
+#endif /* __LITTLE_ENDIAN */
+			unsigned long long full;
+		} tsc[NR_CPUS], *local_tsc;
+		unsigned long stamp, flags;
+		unsigned long long result;
+
+		local_irq_save_hw(flags);
+		local_tsc = &tsc[ipipe_processor_id()];
+		stamp = OSCR;
+		if (unlikely(stamp < local_tsc->low))
+			/* 32 bit counter wrapped, increment high word. */
+			local_tsc->high++;
+		local_tsc->low = stamp;
+		result = local_tsc->full;
+		local_irq_restore_hw(flags);
+
+		return result;
+	}
+	
+        return 0;
+}
+EXPORT_SYMBOL(__ipipe_mach_get_tsc);
+
+/*
+ * Reprogram the timer
+ */
+
+void __ipipe_mach_set_dec(unsigned long delay)
+{
+	unsigned long flags;
+
+	local_irq_save_hw(flags);
+        OSMR0 = delay + OSCR;
+	local_irq_restore_hw(flags);
+}
+EXPORT_SYMBOL(__ipipe_mach_set_dec);
+
+unsigned long __ipipe_mach_get_dec(void)
+{
+	return OSMR0 - OSCR;
+}
+#endif /* CONFIG_IPIPE */

[-- Attachment #3: test_gettimeofday.c --]
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#include <stdio.h>
#include <time.h>
#include <sys/time.h>

int main(void)
{
	struct timeval tv, old_tv;

	gettimeofday(&old_tv, NULL);
	for (;;) {
		gettimeofday(&tv, NULL);
		if (tv.tv_sec < old_tv.tv_sec ||
		    (tv.tv_sec == old_tv.tv_sec && tv.tv_usec < old_tv.tv_usec))
			printf("Time is going backward !\n");
		old_tv = tv;
	}
}