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dfc40b24c0
The smp_twd clockevents driver currently enables the local timer PPI before the clockevents device is registered. This can lead to a kernel panic if a spurious timer interrupt is generated before registration has completed since the kernel will treat it as an IPI timer. This patch moves the clockevents device registration before the IRQ unmasking so that we can always handle timer interrupts once they can occur. Acked-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
145 lines
3.5 KiB
C
145 lines
3.5 KiB
C
/*
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* linux/arch/arm/kernel/smp_twd.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/clockchips.h>
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#include <linux/irq.h>
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#include <linux/io.h>
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#include <asm/smp_twd.h>
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#include <asm/hardware/gic.h>
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/* set up by the platform code */
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void __iomem *twd_base;
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static unsigned long twd_timer_rate;
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static void twd_set_mode(enum clock_event_mode mode,
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struct clock_event_device *clk)
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{
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unsigned long ctrl;
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switch (mode) {
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case CLOCK_EVT_MODE_PERIODIC:
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/* timer load already set up */
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ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
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| TWD_TIMER_CONTROL_PERIODIC;
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__raw_writel(twd_timer_rate / HZ, twd_base + TWD_TIMER_LOAD);
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break;
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case CLOCK_EVT_MODE_ONESHOT:
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/* period set, and timer enabled in 'next_event' hook */
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ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
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break;
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case CLOCK_EVT_MODE_UNUSED:
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case CLOCK_EVT_MODE_SHUTDOWN:
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default:
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ctrl = 0;
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}
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__raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
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}
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static int twd_set_next_event(unsigned long evt,
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struct clock_event_device *unused)
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{
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unsigned long ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL);
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ctrl |= TWD_TIMER_CONTROL_ENABLE;
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__raw_writel(evt, twd_base + TWD_TIMER_COUNTER);
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__raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
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return 0;
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}
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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 twd_timer_ack(void)
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{
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if (__raw_readl(twd_base + TWD_TIMER_INTSTAT)) {
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__raw_writel(1, twd_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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static void __cpuinit twd_calibrate_rate(void)
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{
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unsigned long count;
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u64 waitjiffies;
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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 (twd_timer_rate == 0) {
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printk(KERN_INFO "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, twd_base + TWD_TIMER_CONTROL);
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/* maximum value */
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__raw_writel(0xFFFFFFFFU, twd_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(twd_base + TWD_TIMER_COUNTER);
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twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
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printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
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(twd_timer_rate / 10000) % 100);
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}
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}
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/*
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* Setup the local clock events for a CPU.
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*/
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void __cpuinit twd_timer_setup(struct clock_event_device *clk)
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{
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twd_calibrate_rate();
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clk->name = "local_timer";
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clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
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CLOCK_EVT_FEAT_C3STOP;
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clk->rating = 350;
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clk->set_mode = twd_set_mode;
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clk->set_next_event = twd_set_next_event;
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clk->shift = 20;
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clk->mult = div_sc(twd_timer_rate, NSEC_PER_SEC, clk->shift);
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clk->max_delta_ns = clockevent_delta2ns(0xffffffff, clk);
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clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
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clockevents_register_device(clk);
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/* Make sure our local interrupt controller has this enabled */
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gic_enable_ppi(clk->irq);
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}
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