ARC: SMP support
ARC common code to enable a SMP system + ISS provided SMP extensions. ARC700 natively lacks SMP support, hence some of the core features are are only enabled if SoCs have the necessary h/w pixie-dust. This includes: -Inter Processor Interrupts (IPI) -Cache coherency -load-locked/store-conditional ... The low level exception handling would be completely broken in SMP because we don't have hardware assisted stack switching. Thus a fair bit of this code is repurposing the MMU_SCRATCH reg for event handler prologues to keep them re-entrant. Many thanks to Rajeshwar Ranga for his initial "major" contributions to SMP Port (back in 2008), and to Noam Camus and Gilad Ben-Yossef for help with resurrecting that in 3.2 kernel (2012). Note that this platform code is again singleton design pattern - so multiple SMP platforms won't build at the moment - this deficiency is addressed in subsequent patches within this series. Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Rajeshwar Ranga <rajeshwar.ranga@gmail.com> Cc: Noam Camus <noamc@ezchip.com> Cc: Gilad Ben-Yossef <gilad@benyossef.com>
This commit is contained in:
Vineet Gupta
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arch/arc/kernel/smp.c
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320
arch/arc/kernel/smp.c
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/*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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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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* RajeshwarR: Dec 11, 2007
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* -- Added support for Inter Processor Interrupts
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*
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* Vineetg: Nov 1st, 2007
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* -- Initial Write (Borrowed heavily from ARM)
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/spinlock.h>
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#include <linux/sched.h>
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#include <linux/interrupt.h>
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#include <linux/profile.h>
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#include <linux/errno.h>
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#include <linux/err.h>
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#include <linux/mm.h>
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#include <linux/cpu.h>
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#include <linux/smp.h>
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#include <linux/irq.h>
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#include <linux/delay.h>
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#include <linux/atomic.h>
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#include <linux/percpu.h>
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#include <linux/cpumask.h>
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#include <linux/spinlock_types.h>
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#include <linux/reboot.h>
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#include <asm/processor.h>
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#include <asm/setup.h>
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arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
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arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
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/* XXX: per cpu ? Only needed once in early seconday boot */
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struct task_struct *secondary_idle_tsk;
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/* Called from start_kernel */
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void __init smp_prepare_boot_cpu(void)
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{
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}
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/*
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* Initialise the CPU possible map early - this describes the CPUs
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* which may be present or become present in the system.
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*/
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void __init smp_init_cpus(void)
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{
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unsigned int i;
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for (i = 0; i < NR_CPUS; i++)
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set_cpu_possible(i, true);
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}
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/* called from init ( ) => process 1 */
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void __init smp_prepare_cpus(unsigned int max_cpus)
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{
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int i;
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/*
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* Initialise the present map, which describes the set of CPUs
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* actually populated at the present time.
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*/
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for (i = 0; i < max_cpus; i++)
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set_cpu_present(i, true);
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}
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void __init smp_cpus_done(unsigned int max_cpus)
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{
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}
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/*
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* After power-up, a non Master CPU needs to wait for Master to kick start it
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*
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* The default implementation halts
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*
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* This relies on platform specific support allowing Master to directly set
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* this CPU's PC (to be @first_lines_of_secondary() and kick start it.
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*
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* In lack of such h/w assist, platforms can override this function
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* - make this function busy-spin on a token, eventually set by Master
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* (from arc_platform_smp_wakeup_cpu())
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* - Once token is available, jump to @first_lines_of_secondary
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* (using inline asm).
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*
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* Alert: can NOT use stack here as it has not been determined/setup for CPU.
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* If it turns out to be elaborate, it's better to code it in assembly
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*
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*/
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void __attribute__((weak)) arc_platform_smp_wait_to_boot(int cpu)
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{
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/*
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* As a hack for debugging - since debugger will single-step over the
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* FLAG insn - wrap the halt itself it in a self loop
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*/
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__asm__ __volatile__(
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"1: \n"
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" flag 1 \n"
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" b 1b \n");
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}
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/*
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* The very first "C" code executed by secondary
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* Called from asm stub in head.S
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* "current"/R25 already setup by low level boot code
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*/
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void __cpuinit start_kernel_secondary(void)
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{
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struct mm_struct *mm = &init_mm;
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unsigned int cpu = smp_processor_id();
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/* MMU, Caches, Vector Table, Interrupts etc */
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setup_processor();
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atomic_inc(&mm->mm_users);
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atomic_inc(&mm->mm_count);
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current->active_mm = mm;
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notify_cpu_starting(cpu);
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set_cpu_online(cpu, true);
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pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu);
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arc_platform_smp_init_cpu();
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arc_local_timer_setup(cpu);
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local_irq_enable();
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preempt_disable();
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cpu_idle();
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}
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/*
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* Called from kernel_init( ) -> smp_init( ) - for each CPU
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*
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* At this point, Secondary Processor is "HALT"ed:
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* -It booted, but was halted in head.S
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* -It was configured to halt-on-reset
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* So need to wake it up.
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*
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* Essential requirements being where to run from (PC) and stack (SP)
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*/
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int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *idle)
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{
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unsigned long wait_till;
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secondary_idle_tsk = idle;
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pr_info("Idle Task [%d] %p", cpu, idle);
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pr_info("Trying to bring up CPU%u ...\n", cpu);
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arc_platform_smp_wakeup_cpu(cpu,
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(unsigned long)first_lines_of_secondary);
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/* wait for 1 sec after kicking the secondary */
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wait_till = jiffies + HZ;
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while (time_before(jiffies, wait_till)) {
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if (cpu_online(cpu))
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break;
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}
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if (!cpu_online(cpu)) {
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pr_info("Timeout: CPU%u FAILED to comeup !!!\n", cpu);
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return -1;
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}
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secondary_idle_tsk = NULL;
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return 0;
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}
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/*
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* not supported here
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*/
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int __init setup_profiling_timer(unsigned int multiplier)
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{
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return -EINVAL;
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}
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/*****************************************************************************/
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/* Inter Processor Interrupt Handling */
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/*****************************************************************************/
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/*
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* structures for inter-processor calls
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* A Collection of single bit ipi messages
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*
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*/
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/*
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* TODO_rajesh investigate tlb message types.
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* IPI Timer not needed because each ARC has an individual Interrupting Timer
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*/
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enum ipi_msg_type {
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IPI_NOP = 0,
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IPI_RESCHEDULE = 1,
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IPI_CALL_FUNC,
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IPI_CALL_FUNC_SINGLE,
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IPI_CPU_STOP
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};
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struct ipi_data {
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unsigned long bits;
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};
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static DEFINE_PER_CPU(struct ipi_data, ipi_data);
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static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
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{
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unsigned long flags;
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unsigned int cpu;
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local_irq_save(flags);
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for_each_cpu(cpu, callmap) {
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struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
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set_bit(msg, &ipi->bits);
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}
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/* Call the platform specific cross-CPU call function */
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arc_platform_ipi_send(callmap);
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local_irq_restore(flags);
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}
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void smp_send_reschedule(int cpu)
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{
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ipi_send_msg(cpumask_of(cpu), IPI_RESCHEDULE);
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}
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void smp_send_stop(void)
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{
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struct cpumask targets;
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cpumask_copy(&targets, cpu_online_mask);
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cpumask_clear_cpu(smp_processor_id(), &targets);
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ipi_send_msg(&targets, IPI_CPU_STOP);
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}
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void arch_send_call_function_single_ipi(int cpu)
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{
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ipi_send_msg(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
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}
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void arch_send_call_function_ipi_mask(const struct cpumask *mask)
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{
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ipi_send_msg(mask, IPI_CALL_FUNC);
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}
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/*
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* ipi_cpu_stop - handle IPI from smp_send_stop()
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*/
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static void ipi_cpu_stop(unsigned int cpu)
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{
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machine_halt();
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}
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static inline void __do_IPI(unsigned long *ops, struct ipi_data *ipi, int cpu)
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{
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unsigned long msg = 0;
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do {
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msg = find_next_bit(ops, BITS_PER_LONG, msg+1);
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switch (msg) {
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case IPI_RESCHEDULE:
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scheduler_ipi();
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break;
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case IPI_CALL_FUNC:
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generic_smp_call_function_interrupt();
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break;
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case IPI_CALL_FUNC_SINGLE:
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generic_smp_call_function_single_interrupt();
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break;
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case IPI_CPU_STOP:
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ipi_cpu_stop(cpu);
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break;
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}
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} while (msg < BITS_PER_LONG);
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}
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/*
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* arch-common ISR to handle for inter-processor interrupts
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* Has hooks for platform specific IPI
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*/
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irqreturn_t do_IPI(int irq, void *dev_id)
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{
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int cpu = smp_processor_id();
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struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
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unsigned long ops;
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arc_platform_ipi_clear(cpu, irq);
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/*
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* XXX: is this loop really needed
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* And do we need to move ipi_clean inside
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*/
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while ((ops = xchg(&ipi->bits, 0)) != 0)
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__do_IPI(&ops, ipi, cpu);
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return IRQ_HANDLED;
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}
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/*
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* API called by platform code to hookup arch-common ISR to their IPI IRQ
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*/
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static DEFINE_PER_CPU(int, ipi_dev);
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int smp_ipi_irq_setup(int cpu, int irq)
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{
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int *dev_id = &per_cpu(ipi_dev, smp_processor_id());
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return request_percpu_irq(irq, do_IPI, "IPI Interrupt", dev_id);
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}
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