sparc32: generic clockevent support

The kernel uses l14 timers as clockevents. l10 timer is used
as clocksource if platform master_l10_counter isn't constantly
zero. The clocksource is continuous, so it's possible to use
high resolution timers. l10 timer is also used as clockevent
on UP configurations.

This realization is for sun4m, sun4d, sun4c, microsparc-IIep
and LEON platforms. The appropriate LEON changes was made by
Konrad Eisele.

In case of sun4m's oneshot mode, profile irq is zeroed in
smp4m_percpu_timer_interrupt(). It is maybe
needless (double, triple etc overflow does nothing).

sun4d is able to have oneshot mode too, but I haven't
any way to test it. So code of its percpu timer handler
is made as much equal to the current code as possible.

The patch is tested on sun4m box in SMP mode by me,
and tested by Konrad on leon in up mode (leon smp
is broken atm - due to other reasons).

Signed-off-by: Tkhai Kirill <tkhai@yandex.ru>
Tested-by: Konrad Eisele <konrad@gaisler.com> [leon up]
[sam: revised patch to provide generic support for leon]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 26 insertions, 22 deletions

diff --git a/arch/sparc/kernel/pcic.c b/arch/sparc/kernel/pcic.c
index 6edec801e46..118a3f5806a 100644
--- a/arch/sparc/kernel/pcic.c
+++ b/arch/sparc/kernel/pcic.c
@@ -703,31 +703,28 @@ static void pcic_clear_clock_irq(void)
 	pcic_timer_dummy = readl(pcic0.pcic_regs+PCI_SYS_LIMIT);
 }
 
-static irqreturn_t pcic_timer_handler (int irq, void *h)
+/* CPU frequency is 100 MHz, timer increments every 4 CPU clocks */
+#define USECS_PER_JIFFY  (1000000 / HZ)
+#define TICK_TIMER_LIMIT ((100 * 1000000 / 4) / HZ)
+
+static unsigned int pcic_cycles_offset(void)
 {
-	pcic_clear_clock_irq();
-	xtime_update(1);
-#ifndef CONFIG_SMP
-	update_process_times(user_mode(get_irq_regs()));
-#endif
-	return IRQ_HANDLED;
-}
+	u32 value, count;
 
-#define USECS_PER_JIFFY  10000  /* We have 100HZ "standard" timer for sparc */
-#define TICK_TIMER_LIMIT ((100*1000000/4)/100)
+	value = readl(pcic0.pcic_regs + PCI_SYS_COUNTER);
+	count = value & ~PCI_SYS_COUNTER_OVERFLOW;
 
-u32 pci_gettimeoffset(void)
-{
+	if (value & PCI_SYS_COUNTER_OVERFLOW)
+		count += TICK_TIMER_LIMIT;
 	/*
-	 * We divide all by 100
+	 * We divide all by HZ
 	 * to have microsecond resolution and to avoid overflow
 	 */
-	unsigned long count =
-	    readl(pcic0.pcic_regs+PCI_SYS_COUNTER) & ~PCI_SYS_COUNTER_OVERFLOW;
-	count = ((count/100)*USECS_PER_JIFFY) / (TICK_TIMER_LIMIT/100);
-	return count * 1000;
-}
+	count = ((count / HZ) * USECS_PER_JIFFY) / (TICK_TIMER_LIMIT / HZ);
 
+	/* Coordinate with the fact that timer_cs rate is 2MHz */
+	return count * 2;
+}
 
 void __init pci_time_init(void)
 {
@@ -736,9 +733,16 @@ void __init pci_time_init(void)
 	int timer_irq, irq;
 	int err;
 
-	do_arch_gettimeoffset = pci_gettimeoffset;
-
-	btfixup();
+#ifndef CONFIG_SMP
+	/*
+	 * It's in SBUS dimension, because timer_cs is in this dimension.
+	 * We take into account this in pcic_cycles_offset()
+	 */
+	timer_cs_period = SBUS_CLOCK_RATE / HZ;
+	sparc_config.features |= FEAT_L10_CLOCKEVENT;
+#endif
+	sparc_config.features |= FEAT_L10_CLOCKSOURCE;
+	sparc_config.get_cycles_offset = pcic_cycles_offset;
 
 	writel (TICK_TIMER_LIMIT, pcic->pcic_regs+PCI_SYS_LIMIT);
 	/* PROM should set appropriate irq */
@@ -747,7 +751,7 @@ void __init pci_time_init(void)
 	writel (PCI_COUNTER_IRQ_SET(timer_irq, 0),
 		pcic->pcic_regs+PCI_COUNTER_IRQ);
 	irq = pcic_build_device_irq(NULL, timer_irq);
-	err = request_irq(irq, pcic_timer_handler,
+	err = request_irq(irq, timer_interrupt,
 			  IRQF_TIMER, "timer", NULL);
 	if (err) {
 		prom_printf("time_init: unable to attach IRQ%d\n", timer_irq);