clocksource: convert footbridge to generic i8253 clocksource

Convert the footbridge isa-timer code to use generic i8253 clocksource.

Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

4 files changed, 23 insertions, 41 deletions

diff --git a/arch/arm/include/asm/i8253.h b/arch/arm/include/asm/i8253.h
new file mode 100644
index 000000000000..70656b69d5ce
--- /dev/null
+++ b/arch/arm/include/asm/i8253.h
@@ -0,0 +1,15 @@
+#ifndef __ASMARM_I8253_H
+#define __ASMARM_I8253_H
+
+/* i8253A PIT registers */
+#define PIT_MODE        0x43
+#define PIT_CH0         0x40
+
+#define PIT_LATCH       ((PIT_TICK_RATE + HZ / 2) / HZ)
+
+extern raw_spinlock_t i8253_lock;
+
+#define outb_pit        outb_p
+#define inb_pit         inb_p
+
+#endif
diff --git a/arch/arm/mach-footbridge/Kconfig b/arch/arm/mach-footbridge/Kconfig
index bdd257921cfb..46adca068f2c 100644
--- a/arch/arm/mach-footbridge/Kconfig
+++ b/arch/arm/mach-footbridge/Kconfig
@@ -4,6 +4,7 @@ menu "Footbridge Implementations"
 
 config ARCH_CATS
         bool "CATS"
+        select CLKSRC_I8253
         select FOOTBRIDGE_HOST
         select ISA
         select ISA_DMA
@@ -59,6 +60,7 @@ config ARCH_EBSA285_HOST
 
 config ARCH_NETWINDER
         bool "NetWinder"
+        select CLKSRC_I8253
         select FOOTBRIDGE_HOST
         select ISA
         select ISA_DMA
diff --git a/arch/arm/mach-footbridge/isa-timer.c b/arch/arm/mach-footbridge/isa-timer.c
index 441c6ce0d555..7020f1a3feca 100644
--- a/arch/arm/mach-footbridge/isa-timer.c
+++ b/arch/arm/mach-footbridge/isa-timer.c
@@ -10,53 +10,16 @@
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/io.h>
+#include <linux/spinlock.h>
 #include <linux/timex.h>
 
 #include <asm/irq.h>
-
+#include <asm/i8253.h>
 #include <asm/mach/time.h>
 
 #include "common.h"
 
-#define PIT_MODE        0x43
-#define PIT_CH0         0x40
-
-#define PIT_LATCH       ((PIT_TICK_RATE + HZ / 2) / HZ)
-
-static cycle_t pit_read(struct clocksource *cs)
-{
-        unsigned long flags;
-        static int old_count;
-        static u32 old_jifs;
-        int count;
-        u32 jifs;
-
-        raw_local_irq_save(flags);
-
-        jifs = jiffies;
-        outb_p(0x00, PIT_MODE);         /* latch the count */
-        count = inb_p(PIT_CH0);         /* read the latched count */
-        count |= inb_p(PIT_CH0) << 8;
-
-        if (count > old_count && jifs == old_jifs)
-                count = old_count;
-
-        old_count = count;
-        old_jifs = jifs;
-
-        raw_local_irq_restore(flags);
-
-        count = (PIT_LATCH - 1) - count;
-
-        return (cycle_t)(jifs * PIT_LATCH) + count;
-}
-
-static struct clocksource pit_cs = {
-        .name           = "pit",
-        .rating         = 110,
-        .read           = pit_read,
-        .mask           = CLOCKSOURCE_MASK(32),
-};
+DEFINE_RAW_SPINLOCK(i8253_lock);
 
 static void pit_set_mode(enum clock_event_mode mode,
         struct clock_event_device *evt)
@@ -121,7 +84,7 @@ static void __init isa_timer_init(void)
         pit_ce.max_delta_ns = clockevent_delta2ns(0x7fff, &pit_ce);
         pit_ce.min_delta_ns = clockevent_delta2ns(0x000f, &pit_ce);
 
-        clocksource_register_hz(&pit_cs, PIT_TICK_RATE);
+        clocksource_i8253_init();
 
         setup_irq(pit_ce.irq, &pit_timer_irq);
         clockevents_register_device(&pit_ce);
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index c37b21ad5a3b..f13469b3df86 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -341,4 +341,6 @@ static inline void update_vsyscall_tz(void)
 
 extern void timekeeping_notify(struct clocksource *clock);
 
+extern int clocksource_i8253_init(void);
+
 #endif /* _LINUX_CLOCKSOURCE_H */