[ARM] 4260/1: clocksource support for Versatile platform

Update Versatile to use new clocksource infrastructure for basic timekeeping.

Signed-off-by: Kevin Hilman <khilman@mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 35 insertions, 41 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 2aadd0e1e586..cddd054676c0 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -166,6 +166,7 @@ config ARCH_VERSATILE
         select ARM_AMBA
         select ARM_VIC
         select ICST307
+        select GENERIC_TIME
         help
           This enables support for ARM Ltd Versatile board.
 
diff --git a/arch/arm/mach-versatile/core.c b/arch/arm/mach-versatile/core.c
index bf71507c76fd..08a9fe6eeadb 100644
--- a/arch/arm/mach-versatile/core.c
+++ b/arch/arm/mach-versatile/core.c
@@ -26,6 +26,7 @@
 #include <linux/interrupt.h>
 #include <linux/amba/bus.h>
 #include <linux/amba/clcd.h>
+#include <linux/clocksource.h>
 
 #include <asm/cnt32_to_63.h>
 #include <asm/system.h>
@@ -829,46 +830,6 @@ void __init versatile_init(void)
 #endif
 
 /*
- * Returns number of ms since last clock interrupt.  Note that interrupts
- * will have been disabled by do_gettimeoffset()
- */
-static unsigned long versatile_gettimeoffset(void)
-{
-        unsigned long ticks1, ticks2, status;
-
-        /*
-         * Get the current number of ticks.  Note that there is a race
-         * condition between us reading the timer and checking for
-         * an interrupt.  We get around this by ensuring that the
-         * counter has not reloaded between our two reads.
-         */
-        ticks2 = readl(TIMER0_VA_BASE + TIMER_VALUE) & 0xffff;
-        do {
-                ticks1 = ticks2;
-                status = __raw_readl(VA_IC_BASE + VIC_RAW_STATUS);
-                ticks2 = readl(TIMER0_VA_BASE + TIMER_VALUE) & 0xffff;
-        } while (ticks2 > ticks1);
-
-        /*
-         * Number of ticks since last interrupt.
-         */
-        ticks1 = TIMER_RELOAD - ticks2;
-
-        /*
-         * Interrupt pending?  If so, we've reloaded once already.
-         *
-         * FIXME: Need to check this is effectively timer 0 that expires
-         */
-        if (status & IRQMASK_TIMERINT0_1)
-                ticks1 += TIMER_RELOAD;
-
-        /*
-         * Convert the ticks to usecs
-         */
-        return TICKS2USECS(ticks1);
-}
-
-/*
  * IRQ handler for the timer
  */
 static irqreturn_t versatile_timer_interrupt(int irq, void *dev_id)
@@ -891,6 +852,36 @@ static struct irqaction versatile_timer_irq = {
         .handler        = versatile_timer_interrupt,
 };
 
+static cycle_t versatile_get_cycles(void)
+{
+        return ~readl(TIMER3_VA_BASE + TIMER_VALUE);
+}
+
+static struct clocksource clocksource_versatile = {
+        .name           = "timer3",
+        .rating         = 200,
+        .read           = versatile_get_cycles,
+        .mask           = CLOCKSOURCE_MASK(32),
+        .shift          = 20,
+        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int __init versatile_clocksource_init(void)
+{
+        /* setup timer3 as free-running clocksource */
+        writel(0, TIMER3_VA_BASE + TIMER_CTRL);
+        writel(0xffffffff, TIMER3_VA_BASE + TIMER_LOAD);
+        writel(0xffffffff, TIMER3_VA_BASE + TIMER_VALUE);
+        writel(TIMER_CTRL_32BIT | TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC,
+               TIMER3_VA_BASE + TIMER_CTRL);
+
+        clocksource_versatile.mult =
+                clocksource_khz2mult(1000, clocksource_versatile.shift);
+        clocksource_register(&clocksource_versatile);
+
+        return 0;
+}
+
 /*
  * Set up timer interrupt, and return the current time in seconds.
  */
@@ -927,9 +918,11 @@ static void __init versatile_timer_init(void)
          * Make irqs happen for the system timer
          */
         setup_irq(IRQ_TIMERINT0_1, &versatile_timer_irq);
+
+        versatile_clocksource_init();
 }
 
 struct sys_timer versatile_timer = {
         .init           = versatile_timer_init,
-        .offset         = versatile_gettimeoffset,
 };
+