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, 29 insertions, 0 deletions

diff --git a/arch/sparc/include/asm/timer_32.h b/arch/sparc/include/asm/timer_32.h
index 1a91e11dd104..e6e66678f470 100644
--- a/arch/sparc/include/asm/timer_32.h
+++ b/arch/sparc/include/asm/timer_32.h
@@ -8,11 +8,40 @@
 #ifndef _SPARC_TIMER_H
 #define _SPARC_TIMER_H
 
+#include <linux/clocksource.h>
+#include <linux/irqreturn.h>
+
+#include <asm-generic/percpu.h>
+
 #include <asm/cpu_type.h>  /* For SUN4M_NCPUS */
 #include <asm/btfixup.h>
 
+#define SBUS_CLOCK_RATE   2000000 /* 2MHz */
+#define TIMER_VALUE_SHIFT 9
+#define TIMER_VALUE_MASK  0x3fffff
+#define TIMER_LIMIT_BIT   (1 << 31)  /* Bit 31 in Counter-Timer register */
+
+/* The counter timer register has the value offset by 9 bits.
+ * From sun4m manual:
+ * When a counter reaches the value in the corresponding limit register,
+ * the Limit bit is set and the counter is set to 500 nS (i.e. 0x00000200).
+ *
+ * To compensate for this add one to the value.
+ */
+static inline unsigned int timer_value(unsigned int value)
+{
+	return (value + 1) << TIMER_VALUE_SHIFT;
+}
+
 extern __volatile__ unsigned int *master_l10_counter;
 
+extern irqreturn_t notrace timer_interrupt(int dummy, void *dev_id);
+
+#ifdef CONFIG_SMP
+DECLARE_PER_CPU(struct clock_event_device, sparc32_clockevent);
+extern void register_percpu_ce(int cpu);
+#endif
+
 /* FIXME: Make do_[gs]ettimeofday btfixup calls */
 struct timespec;
 BTFIXUPDEF_CALL(int, bus_do_settimeofday, struct timespec *tv)