a8655e83fc
This patch adds dummy local timers for each CPU so that the board clock device is used to broadcast events to the other CPUs. The patch also adds the declaration for the dummy_timer_setup function (the equivalent of local_timer_setup when CONFIG_LOCAL_TIMERS is not set). Due to the way clockevents work, the dummy timer on the first CPU has to be registered before the board timer. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
169 lines
4.1 KiB
C
169 lines
4.1 KiB
C
/*
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* linux/arch/arm/mach-realview/localtimer.c
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*
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* Copyright (C) 2002 ARM Ltd.
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/delay.h>
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#include <linux/device.h>
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#include <linux/smp.h>
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#include <linux/jiffies.h>
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#include <linux/percpu.h>
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#include <linux/clockchips.h>
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#include <asm/mach/time.h>
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#include <asm/hardware/arm_twd.h>
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#include <asm/hardware/gic.h>
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#include <asm/hardware.h>
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#include <asm/io.h>
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#include <asm/irq.h>
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#define TWD_BASE(cpu) (__io_address(REALVIEW_TWD_BASE) + \
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((cpu) * REALVIEW_TWD_SIZE))
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static DEFINE_PER_CPU(struct clock_event_device, local_clockevent);
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/*
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* Used on SMP for either the local timer or IPI_TIMER
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*/
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void local_timer_interrupt(void)
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{
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struct clock_event_device *clk = &__get_cpu_var(local_clockevent);
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clk->event_handler(clk);
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}
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#ifdef CONFIG_LOCAL_TIMERS
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static unsigned long mpcore_timer_rate;
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/*
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* local_timer_ack: checks for a local timer interrupt.
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*
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* If a local timer interrupt has occurred, acknowledge and return 1.
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* Otherwise, return 0.
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*/
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int local_timer_ack(void)
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{
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void __iomem *base = TWD_BASE(smp_processor_id());
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if (__raw_readl(base + TWD_TIMER_INTSTAT)) {
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__raw_writel(1, base + TWD_TIMER_INTSTAT);
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return 1;
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}
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return 0;
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}
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void __cpuinit local_timer_setup(unsigned int cpu)
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{
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void __iomem *base = TWD_BASE(cpu);
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unsigned int load, offset;
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u64 waitjiffies;
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unsigned int count;
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/*
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* If this is the first time round, we need to work out how fast
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* the timer ticks
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*/
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if (mpcore_timer_rate == 0) {
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printk("Calibrating local timer... ");
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/* Wait for a tick to start */
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waitjiffies = get_jiffies_64() + 1;
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while (get_jiffies_64() < waitjiffies)
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udelay(10);
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/* OK, now the tick has started, let's get the timer going */
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waitjiffies += 5;
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/* enable, no interrupt or reload */
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__raw_writel(0x1, base + TWD_TIMER_CONTROL);
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/* maximum value */
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__raw_writel(0xFFFFFFFFU, base + TWD_TIMER_COUNTER);
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while (get_jiffies_64() < waitjiffies)
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udelay(10);
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count = __raw_readl(base + TWD_TIMER_COUNTER);
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mpcore_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
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printk("%lu.%02luMHz.\n", mpcore_timer_rate / 1000000,
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(mpcore_timer_rate / 100000) % 100);
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}
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load = mpcore_timer_rate / HZ;
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__raw_writel(load, base + TWD_TIMER_LOAD);
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__raw_writel(0x7, base + TWD_TIMER_CONTROL);
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/*
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* Now maneuver our local tick into the right part of the jiffy.
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* Start by working out where within the tick our local timer
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* interrupt should go.
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*/
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offset = ((mpcore_timer_rate / HZ) / (NR_CPUS + 1)) * (cpu + 1);
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/*
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* gettimeoffset() will return a number of us since the last tick.
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* Convert this number of us to a local timer tick count.
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* Be careful of integer overflow whilst keeping maximum precision.
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*
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* with HZ=100 and 1MHz (fpga) ~ 1GHz processor:
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* load = 1 ~ 10,000
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* mpcore_timer_rate/10000 = 100 ~ 100,000
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*
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* so the multiply value will be less than 10^9 always.
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*/
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load = (system_timer->offset() * (mpcore_timer_rate / 10000)) / 100;
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/* Add on our offset to get the load value */
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load = (load + offset) % (mpcore_timer_rate / HZ);
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__raw_writel(load, base + TWD_TIMER_COUNTER);
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/* Make sure our local interrupt controller has this enabled */
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__raw_writel(1 << IRQ_LOCALTIMER,
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__io_address(REALVIEW_GIC_DIST_BASE) + GIC_DIST_ENABLE_SET);
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}
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/*
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* take a local timer down
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*/
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void __cpuexit local_timer_stop(unsigned int cpu)
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{
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__raw_writel(0, TWD_BASE(cpu) + TWD_TIMER_CONTROL);
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}
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#else /* CONFIG_LOCAL_TIMERS */
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static void dummy_timer_set_mode(enum clock_event_mode mode,
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struct clock_event_device *clk)
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{
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}
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void __cpuinit local_timer_setup(unsigned int cpu)
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{
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struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
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clk->name = "dummy_timer";
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clk->features = CLOCK_EVT_FEAT_DUMMY;
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clk->rating = 200;
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clk->set_mode = dummy_timer_set_mode;
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clk->broadcast = smp_timer_broadcast;
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clk->cpumask = cpumask_of_cpu(cpu);
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clockevents_register_device(clk);
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}
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#endif /* !CONFIG_LOCAL_TIMERS */
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