summaryrefslogtreecommitdiffstats
path: root/arch/arm
diff options
context:
space:
mode:
authorRussell King <rmk@dyn-67.arm.linux.org.uk>2005-11-09 11:50:29 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2005-11-09 11:50:29 +0100
commit2a98beb6390aef8fad85103ea25b3b1ace8015b5 (patch)
tree09f3e0de9a49f0f61d7f44c6c03218bf29f5d1dd /arch/arm
parent[ARM SMP] Add core ARM support for local timers (diff)
downloadlinux-2a98beb6390aef8fad85103ea25b3b1ace8015b5.tar.xz
linux-2a98beb6390aef8fad85103ea25b3b1ace8015b5.zip
[ARM SMP] Add local timer support for Realview MPcore
Add platform specific parts for local timer support for the Realview board. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/Kconfig2
-rw-r--r--arch/arm/mach-realview/Makefile1
-rw-r--r--arch/arm/mach-realview/core.c2
-rw-r--r--arch/arm/mach-realview/localtimer.c130
-rw-r--r--arch/arm/mach-realview/platsmp.c5
5 files changed, 138 insertions, 2 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 3bfef0934c9d..ec77721507cb 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -358,7 +358,7 @@ config HOTPLUG_CPU
config LOCAL_TIMERS
bool "Use local timer interrupts"
- depends on SMP && n
+ depends on SMP && REALVIEW_MPCORE
default y
help
Enable support for local timers on SMP platforms, rather then the
diff --git a/arch/arm/mach-realview/Makefile b/arch/arm/mach-realview/Makefile
index 011a85c10627..a6a40dac26a9 100644
--- a/arch/arm/mach-realview/Makefile
+++ b/arch/arm/mach-realview/Makefile
@@ -5,3 +5,4 @@
obj-y := core.o clock.o
obj-$(CONFIG_MACH_REALVIEW_EB) += realview_eb.o
obj-$(CONFIG_SMP) += platsmp.o headsmp.o
+obj-$(CONFIG_LOCAL_TIMERS) += localtimer.o
diff --git a/arch/arm/mach-realview/core.c b/arch/arm/mach-realview/core.c
index 4ea60d8b6e36..e2c6fa23d3cd 100644
--- a/arch/arm/mach-realview/core.c
+++ b/arch/arm/mach-realview/core.c
@@ -550,7 +550,7 @@ static irqreturn_t realview_timer_interrupt(int irq, void *dev_id, struct pt_reg
timer_tick(regs);
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) && !defined(CONFIG_LOCAL_TIMERS)
smp_send_timer();
update_process_times(user_mode(regs));
#endif
diff --git a/arch/arm/mach-realview/localtimer.c b/arch/arm/mach-realview/localtimer.c
new file mode 100644
index 000000000000..5e917e37d095
--- /dev/null
+++ b/arch/arm/mach-realview/localtimer.c
@@ -0,0 +1,130 @@
+/*
+ * 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);
+}
diff --git a/arch/arm/mach-realview/platsmp.c b/arch/arm/mach-realview/platsmp.c
index 09b35f62247a..0c7d4ac9a7b3 100644
--- a/arch/arm/mach-realview/platsmp.c
+++ b/arch/arm/mach-realview/platsmp.c
@@ -175,6 +175,11 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
max_cpus = ncores;
/*
+ * Enable the local timer for primary CPU
+ */
+ local_timer_setup(cpu);
+
+ /*
* Initialise the possible/present maps.
* cpu_possible_map describes the set of CPUs which may be present
* cpu_present_map describes the set of CPUs populated