ad17a26e22
The periodic mode is currently calculated by a simple division but we should pay more attention to our integer arithmetics. Also delete a comment that does not make any sense. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
391 lines
8.5 KiB
C
391 lines
8.5 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/clk.h>
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#include <linux/delay.h>
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#include <linux/device.h>
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#include <linux/err.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/interrupt.h>
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#include <linux/io.h>
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#include <linux/of_irq.h>
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#include <linux/of_address.h>
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#include <asm/smp_twd.h>
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#include <asm/localtimer.h>
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#include <asm/hardware/gic.h>
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/* set up by the platform code */
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static void __iomem *twd_base;
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static struct clk *twd_clk;
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static unsigned long twd_timer_rate;
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static struct clock_event_device __percpu **twd_evt;
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static int twd_ppi;
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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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ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
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| TWD_TIMER_CONTROL_PERIODIC;
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__raw_writel(DIV_ROUND_CLOSEST(twd_timer_rate, HZ),
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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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static 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 twd_timer_stop(struct clock_event_device *clk)
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{
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twd_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
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disable_percpu_irq(clk->irq);
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}
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#ifdef CONFIG_COMMON_CLK
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/*
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* Updates clockevent frequency when the cpu frequency changes.
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* Called on the cpu that is changing frequency with interrupts disabled.
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*/
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static void twd_update_frequency(void *new_rate)
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{
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twd_timer_rate = *((unsigned long *) new_rate);
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clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
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}
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static int twd_rate_change(struct notifier_block *nb,
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unsigned long flags, void *data)
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{
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struct clk_notifier_data *cnd = data;
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/*
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* The twd clock events must be reprogrammed to account for the new
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* frequency. The timer is local to a cpu, so cross-call to the
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* changing cpu.
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*/
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if (flags == POST_RATE_CHANGE)
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smp_call_function(twd_update_frequency,
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(void *)&cnd->new_rate, 1);
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return NOTIFY_OK;
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}
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static struct notifier_block twd_clk_nb = {
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.notifier_call = twd_rate_change,
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};
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static int twd_clk_init(void)
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{
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if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
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return clk_notifier_register(twd_clk, &twd_clk_nb);
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return 0;
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}
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core_initcall(twd_clk_init);
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#elif defined (CONFIG_CPU_FREQ)
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#include <linux/cpufreq.h>
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/*
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* Updates clockevent frequency when the cpu frequency changes.
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* Called on the cpu that is changing frequency with interrupts disabled.
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*/
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static void twd_update_frequency(void *data)
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{
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twd_timer_rate = clk_get_rate(twd_clk);
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clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
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}
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static int twd_cpufreq_transition(struct notifier_block *nb,
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unsigned long state, void *data)
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{
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struct cpufreq_freqs *freqs = data;
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/*
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* The twd clock events must be reprogrammed to account for the new
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* frequency. The timer is local to a cpu, so cross-call to the
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* changing cpu.
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*/
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if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE)
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smp_call_function_single(freqs->cpu, twd_update_frequency,
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NULL, 1);
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return NOTIFY_OK;
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}
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static struct notifier_block twd_cpufreq_nb = {
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.notifier_call = twd_cpufreq_transition,
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};
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static int twd_cpufreq_init(void)
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{
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if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
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return cpufreq_register_notifier(&twd_cpufreq_nb,
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CPUFREQ_TRANSITION_NOTIFIER);
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return 0;
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}
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core_initcall(twd_cpufreq_init);
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#endif
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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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static irqreturn_t twd_handler(int irq, void *dev_id)
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{
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struct clock_event_device *evt = *(struct clock_event_device **)dev_id;
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if (twd_timer_ack()) {
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evt->event_handler(evt);
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return IRQ_HANDLED;
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}
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return IRQ_NONE;
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}
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static struct clk *twd_get_clock(void)
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{
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struct clk *clk;
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int err;
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clk = clk_get_sys("smp_twd", NULL);
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if (IS_ERR(clk)) {
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pr_err("smp_twd: clock not found: %d\n", (int)PTR_ERR(clk));
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return clk;
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}
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err = clk_prepare(clk);
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if (err) {
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pr_err("smp_twd: clock failed to prepare: %d\n", err);
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clk_put(clk);
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return ERR_PTR(err);
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}
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err = clk_enable(clk);
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if (err) {
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pr_err("smp_twd: clock failed to enable: %d\n", err);
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clk_unprepare(clk);
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clk_put(clk);
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return ERR_PTR(err);
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}
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return clk;
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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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static int __cpuinit twd_timer_setup(struct clock_event_device *clk)
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{
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struct clock_event_device **this_cpu_clk;
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if (!twd_clk)
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twd_clk = twd_get_clock();
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if (!IS_ERR_OR_NULL(twd_clk))
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twd_timer_rate = clk_get_rate(twd_clk);
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else
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twd_calibrate_rate();
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__raw_writel(0, twd_base + TWD_TIMER_CONTROL);
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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->irq = twd_ppi;
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this_cpu_clk = __this_cpu_ptr(twd_evt);
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*this_cpu_clk = clk;
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clockevents_config_and_register(clk, twd_timer_rate,
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0xf, 0xffffffff);
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enable_percpu_irq(clk->irq, 0);
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return 0;
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}
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static struct local_timer_ops twd_lt_ops __cpuinitdata = {
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.setup = twd_timer_setup,
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.stop = twd_timer_stop,
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};
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static int __init twd_local_timer_common_register(void)
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{
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int err;
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twd_evt = alloc_percpu(struct clock_event_device *);
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if (!twd_evt) {
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err = -ENOMEM;
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goto out_free;
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}
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err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
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if (err) {
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pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
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goto out_free;
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}
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err = local_timer_register(&twd_lt_ops);
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if (err)
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goto out_irq;
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return 0;
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out_irq:
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free_percpu_irq(twd_ppi, twd_evt);
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out_free:
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iounmap(twd_base);
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twd_base = NULL;
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free_percpu(twd_evt);
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return err;
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}
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int __init twd_local_timer_register(struct twd_local_timer *tlt)
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{
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if (twd_base || twd_evt)
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return -EBUSY;
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twd_ppi = tlt->res[1].start;
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twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
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if (!twd_base)
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return -ENOMEM;
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return twd_local_timer_common_register();
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}
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#ifdef CONFIG_OF
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const static struct of_device_id twd_of_match[] __initconst = {
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{ .compatible = "arm,cortex-a9-twd-timer", },
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{ .compatible = "arm,cortex-a5-twd-timer", },
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{ .compatible = "arm,arm11mp-twd-timer", },
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{ },
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};
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void __init twd_local_timer_of_register(void)
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{
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struct device_node *np;
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int err;
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np = of_find_matching_node(NULL, twd_of_match);
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if (!np) {
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err = -ENODEV;
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goto out;
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}
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twd_ppi = irq_of_parse_and_map(np, 0);
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if (!twd_ppi) {
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err = -EINVAL;
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goto out;
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}
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twd_base = of_iomap(np, 0);
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if (!twd_base) {
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err = -ENOMEM;
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goto out;
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}
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err = twd_local_timer_common_register();
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out:
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WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
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}
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#endif
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