[ARM] 4811/1: RealView: clocksource support for the RealView platforms

The patch updates the RealView platform code to use the generic
clocksource infrastructure for basic time keeping. Based on the
Versatile implementation by Kevin Hilman.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 4b1a8e3d292cfe74c864790c30cb08ca8dd59f63..a2b7e4a52f73b054a7410927ff2ccb9337fb2dc3 100644 (file)
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -168,6 +168,7 @@ config ARCH_REALVIEW
        bool "ARM Ltd. RealView family"
        select ARM_AMBA
        select ICST307
+       select GENERIC_TIME
        help
          This enables support for ARM Ltd RealView boards.
 

diff --git a/arch/arm/mach-realview/core.c b/arch/arm/mach-realview/core.c
index 61d70218f1e8adc60aee99d0e044700cb2fe6fd2..f805840f6f440d24c5c68bb4d7273065b4a77e1b 100644 (file)
--- a/arch/arm/mach-realview/core.c
+++ b/arch/arm/mach-realview/core.c
@@ -25,6 +25,7 @@
 #include <linux/interrupt.h>
 #include <linux/amba/bus.h>
 #include <linux/amba/clcd.h>
+#include <linux/clocksource.h>
 
 #include <asm/system.h>
 #include <asm/hardware.h>
@@ -484,47 +485,6 @@ void realview_leds_event(led_event_t ledevt)
 #define TICKS2USECS(x) ((x) / TICKS_PER_uSEC)
 #endif
 
-/*
- * Returns number of ms since last clock interrupt.  Note that interrupts
- * will have been disabled by do_gettimeoffset()
- */
-static unsigned long realview_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(__io_address(REALVIEW_GIC_DIST_BASE + GIC_DIST_PENDING_SET)
-                                    + ((IRQ_TIMERINT0_1 >> 5) << 2));
-               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
  */
@@ -549,6 +509,34 @@ static struct irqaction realview_timer_irq = {
        .handler        = realview_timer_interrupt,
 };
 
+static cycle_t realview_get_cycles(void)
+{
+       return ~readl(TIMER3_VA_BASE + TIMER_VALUE);
+}
+
+static struct clocksource clocksource_realview = {
+       .name   = "timer3",
+       .rating = 200,
+       .read   = realview_get_cycles,
+       .mask   = CLOCKSOURCE_MASK(32),
+       .shift  = 20,
+       .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static void __init realview_clocksource_init(void)
+{
+       /* setup timer 0 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_realview.mult =
+               clocksource_khz2mult(1000, clocksource_realview.shift);
+       clocksource_register(&clocksource_realview);
+}
+
 /*
  * Set up timer interrupt, and return the current time in seconds.
  */
@@ -585,9 +573,10 @@ static void __init realview_timer_init(void)
         * Make irqs happen for the system timer
         */
        setup_irq(IRQ_TIMERINT0_1, &realview_timer_irq);
+
+       realview_clocksource_init();
 }
 
 struct sys_timer realview_timer = {
        .init           = realview_timer_init,
-       .offset         = realview_gettimeoffset,
 };