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340 lines
7.6 KiB
340 lines
7.6 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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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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#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/cpu.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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/* 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 DEFINE_PER_CPU(bool, percpu_setup_called); |
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static struct clock_event_device __percpu *twd_evt; |
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static unsigned int twd_features = |
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CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT; |
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static int twd_ppi; |
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static int twd_shutdown(struct clock_event_device *clk) |
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{ |
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writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); |
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return 0; |
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} |
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static int twd_set_oneshot(struct clock_event_device *clk) |
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{ |
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/* period set, and timer enabled in 'next_event' hook */ |
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writel_relaxed(TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT, |
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twd_base + TWD_TIMER_CONTROL); |
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return 0; |
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} |
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static int twd_set_periodic(struct clock_event_device *clk) |
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{ |
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unsigned long ctrl = TWD_TIMER_CONTROL_ENABLE | |
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TWD_TIMER_CONTROL_IT_ENABLE | |
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TWD_TIMER_CONTROL_PERIODIC; |
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writel_relaxed(DIV_ROUND_CLOSEST(twd_timer_rate, HZ), |
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twd_base + TWD_TIMER_LOAD); |
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writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL); |
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return 0; |
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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 = readl_relaxed(twd_base + TWD_TIMER_CONTROL); |
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ctrl |= TWD_TIMER_CONTROL_ENABLE; |
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writel_relaxed(evt, twd_base + TWD_TIMER_COUNTER); |
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writel_relaxed(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 (readl_relaxed(twd_base + TWD_TIMER_INTSTAT)) { |
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writel_relaxed(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(void) |
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{ |
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struct clock_event_device *clk = raw_cpu_ptr(twd_evt); |
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twd_shutdown(clk); |
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disable_percpu_irq(clk->irq); |
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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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clockevents_update_freq(raw_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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on_each_cpu(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 && raw_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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static void 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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pr_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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writel_relaxed(0x1, twd_base + TWD_TIMER_CONTROL); |
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/* maximum value */ |
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writel_relaxed(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 = readl_relaxed(twd_base + TWD_TIMER_COUNTER); |
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twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5); |
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pr_cont("%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 = 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 void twd_get_clock(struct device_node *np) |
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{ |
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int err; |
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if (np) |
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twd_clk = of_clk_get(np, 0); |
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else |
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twd_clk = clk_get_sys("smp_twd", NULL); |
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if (IS_ERR(twd_clk)) { |
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pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk)); |
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return; |
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} |
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err = clk_prepare_enable(twd_clk); |
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if (err) { |
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pr_err("smp_twd: clock failed to prepare+enable: %d\n", err); |
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clk_put(twd_clk); |
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return; |
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} |
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twd_timer_rate = clk_get_rate(twd_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 void twd_timer_setup(void) |
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{ |
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struct clock_event_device *clk = raw_cpu_ptr(twd_evt); |
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int cpu = smp_processor_id(); |
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/* |
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* If the basic setup for this CPU has been done before don't |
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* bother with the below. |
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*/ |
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if (per_cpu(percpu_setup_called, cpu)) { |
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writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); |
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clockevents_register_device(clk); |
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enable_percpu_irq(clk->irq, 0); |
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return; |
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} |
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per_cpu(percpu_setup_called, cpu) = true; |
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twd_calibrate_rate(); |
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/* |
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* The following is done once per CPU the first time .setup() is |
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* called. |
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*/ |
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writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); |
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clk->name = "local_timer"; |
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clk->features = twd_features; |
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clk->rating = 350; |
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clk->set_state_shutdown = twd_shutdown; |
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clk->set_state_periodic = twd_set_periodic; |
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clk->set_state_oneshot = twd_set_oneshot; |
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clk->tick_resume = twd_shutdown; |
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clk->set_next_event = twd_set_next_event; |
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clk->irq = twd_ppi; |
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clk->cpumask = cpumask_of(cpu); |
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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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} |
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static int twd_timer_starting_cpu(unsigned int cpu) |
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{ |
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twd_timer_setup(); |
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return 0; |
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} |
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static int twd_timer_dying_cpu(unsigned int cpu) |
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{ |
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twd_timer_stop(); |
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return 0; |
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} |
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static int __init twd_local_timer_common_register(struct device_node *np) |
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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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cpuhp_setup_state_nocalls(CPUHP_AP_ARM_TWD_STARTING, |
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"arm/timer/twd:starting", |
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twd_timer_starting_cpu, twd_timer_dying_cpu); |
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twd_get_clock(np); |
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if (!of_property_read_bool(np, "always-on")) |
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twd_features |= CLOCK_EVT_FEAT_C3STOP; |
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/* |
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* Immediately configure the timer on the boot CPU, unless we need |
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* jiffies to be incrementing to calibrate the rate in which case |
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* setup the timer in late_time_init. |
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*/ |
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if (twd_timer_rate) |
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twd_timer_setup(); |
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else |
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late_time_init = twd_timer_setup; |
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return 0; |
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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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static int __init twd_local_timer_of_register(struct device_node *np) |
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{ |
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int err; |
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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(np); |
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out: |
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WARN(err, "twd_local_timer_of_register failed (%d)\n", err); |
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return err; |
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} |
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TIMER_OF_DECLARE(arm_twd_a9, "arm,cortex-a9-twd-timer", twd_local_timer_of_register); |
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TIMER_OF_DECLARE(arm_twd_a5, "arm,cortex-a5-twd-timer", twd_local_timer_of_register); |
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TIMER_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", twd_local_timer_of_register);
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