[ARM] 4811/1: RealView: clocksource support for the RealView platforms
authorCatalin Marinas <catalin.marinas@arm.com>
Mon, 4 Feb 2008 16:24:54 +0000 (17:24 +0100)
committerRussell King <rmk+kernel@arm.linux.org.uk>
Mon, 4 Feb 2008 17:52:16 +0000 (17:52 +0000)
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>
arch/arm/Kconfig
arch/arm/mach-realview/core.c

index 4b1a8e3d292cfe74c864790c30cb08ca8dd59f63..a2b7e4a52f73b054a7410927ff2ccb9337fb2dc3 100644 (file)
@@ -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.
 
index 61d70218f1e8adc60aee99d0e044700cb2fe6fd2..f805840f6f440d24c5c68bb4d7273065b4a77e1b 100644 (file)
@@ -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,
 };