--- /dev/null
+/*
+ * linux/arch/arm/mach-realview/localtimer.c
+ *
+ * Copyright (C) 2002 ARM Ltd.
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/smp.h>
+
+#include <asm/mach/time.h>
+#include <asm/hardware/arm_twd.h>
+#include <asm/hardware/gic.h>
+#include <asm/hardware.h>
+#include <asm/io.h>
+#include <asm/irq.h>
+
+#include "core.h"
+
+#define TWD_BASE(cpu) (__io_address(REALVIEW_TWD_BASE) + \
+ ((cpu) * REALVIEW_TWD_SIZE))
+
+static unsigned long mpcore_timer_rate;
+
+/*
+ * local_timer_ack: checks for a local timer interrupt.
+ *
+ * If a local timer interrupt has occured, acknowledge and return 1.
+ * Otherwise, return 0.
+ */
+int local_timer_ack(void)
+{
+ void __iomem *base = TWD_BASE(smp_processor_id());
+
+ if (__raw_readl(base + TWD_TIMER_INTSTAT)) {
+ __raw_writel(1, base + TWD_TIMER_INTSTAT);
+ return 1;
+ }
+
+ return 0;
+}
+
+void __cpuinit local_timer_setup(unsigned int cpu)
+{
+ void __iomem *base = TWD_BASE(cpu);
+ unsigned int load, offset;
+ u64 waitjiffies;
+ unsigned int count;
+
+ /*
+ * If this is the first time round, we need to work out how fast
+ * the timer ticks
+ */
+ if (mpcore_timer_rate == 0) {
+ printk("Calibrating local timer... ");
+
+ /* Wait for a tick to start */
+ waitjiffies = get_jiffies_64() + 1;
+
+ while (get_jiffies_64() < waitjiffies)
+ udelay(10);
+
+ /* OK, now the tick has started, let's get the timer going */
+ waitjiffies += 5;
+
+ /* enable, no interrupt or reload */
+ __raw_writel(0x1, base + TWD_TIMER_CONTROL);
+
+ /* maximum value */
+ __raw_writel(0xFFFFFFFFU, base + TWD_TIMER_COUNTER);
+
+ while (get_jiffies_64() < waitjiffies)
+ udelay(10);
+
+ count = __raw_readl(base + TWD_TIMER_COUNTER);
+
+ mpcore_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
+
+ printk("%lu.%02luMHz.\n", mpcore_timer_rate / 1000000,
+ (mpcore_timer_rate / 100000) % 100);
+ }
+
+ load = mpcore_timer_rate / HZ;
+
+ __raw_writel(load, base + TWD_TIMER_LOAD);
+ __raw_writel(0x7, base + TWD_TIMER_CONTROL);
+
+ /*
+ * Now maneuver our local tick into the right part of the jiffy.
+ * Start by working out where within the tick our local timer
+ * interrupt should go.
+ */
+ offset = ((mpcore_timer_rate / HZ) / (NR_CPUS + 1)) * (cpu + 1);
+
+ /*
+ * gettimeoffset() will return a number of us since the last tick.
+ * Convert this number of us to a local timer tick count.
+ * Be careful of integer overflow whilst keeping maximum precision.
+ *
+ * with HZ=100 and 1MHz (fpga) ~ 1GHz processor:
+ * load = 1 ~ 10,000
+ * mpcore_timer_rate/10000 = 100 ~ 100,000
+ *
+ * so the multiply value will be less than 10^9 always.
+ */
+ load = (system_timer->offset() * (mpcore_timer_rate / 10000)) / 100;
+
+ /* Add on our offset to get the load value */
+ load = (load + offset) % (mpcore_timer_rate / HZ);
+
+ __raw_writel(load, base + TWD_TIMER_COUNTER);
+
+ /* Make sure our local interrupt controller has this enabled */
+ __raw_writel(1 << IRQ_LOCALTIMER,
+ __io_address(REALVIEW_GIC_DIST_BASE) + GIC_DIST_ENABLE_SET);
+}
+
+/*
+ * take a local timer down
+ */
+void __cpuexit local_timer_stop(unsigned int cpu)
+{
+ __raw_writel(0, TWD_BASE(cpu) + TWD_TIMER_CONTROL);
+}
projects / linux-2.6 / commitdiff