[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>

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