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+/*
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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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+
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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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+
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+/* set up by the platform code */
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+static void __iomem *twd_base;
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+
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+static struct clk *twd_clk;
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+static unsigned long twd_timer_rate;
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+static bool common_setup_called;
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+static DEFINE_PER_CPU(bool, percpu_setup_called);
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+
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+static struct clock_event_device __percpu **twd_evt;
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+static int twd_ppi;
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+
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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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+
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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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+
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+ __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
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+}
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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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+
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+ ctrl |= TWD_TIMER_CONTROL_ENABLE;
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+
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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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+
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+ return 0;
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+}
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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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+
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+ return 0;
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+}
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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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+
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+#ifdef CONFIG_COMMON_CLK
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+
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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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+
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+ clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
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+}
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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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+ /*
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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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+
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+ return NOTIFY_OK;
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+}
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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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+
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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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+
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+ return 0;
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+}
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+core_initcall(twd_clk_init);
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+
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+#elif defined (CONFIG_CPU_FREQ)
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+
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+#include <linux/cpufreq.h>
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+
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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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+
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+ clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
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+}
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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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+ /*
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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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+
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+ return NOTIFY_OK;
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+}
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