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eb50439b92
It turns out that the logical CPU mapping is useful even when !CONFIG_SMP for manipulation of devices like interrupt and power controllers when running a UP kernel on a CPU other than 0. This can happen when kexecing a UP image from an SMP kernel. In the future, multi-cluster systems running AMP configurations will require something similar for mapping cluster IDs, so it makes sense to decouple this logic in preparation for this support. Acked-by: Yang Bai <hamo.by@gmail.com> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Reported-by: Joerg Roedel <joerg.roedel@amd.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
93 lines
1.9 KiB
C
93 lines
1.9 KiB
C
/*
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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/kernel.h>
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#include <linux/errno.h>
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#include <linux/smp.h>
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#include <asm/cacheflush.h>
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#include <asm/smp_plat.h>
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extern volatile int pen_release;
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static inline void cpu_enter_lowpower(void)
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{
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/* Just flush the cache. Changing the coherency is not yet
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* available on msm. */
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flush_cache_all();
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}
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static inline void cpu_leave_lowpower(void)
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{
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}
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static inline void platform_do_lowpower(unsigned int cpu)
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{
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/* Just enter wfi for now. TODO: Properly shut off the cpu. */
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for (;;) {
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/*
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* here's the WFI
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*/
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asm("wfi"
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:
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:
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: "memory", "cc");
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if (pen_release == cpu_logical_map(cpu)) {
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/*
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* OK, proper wakeup, we're done
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*/
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break;
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}
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/*
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* getting here, means that we have come out of WFI without
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* having been woken up - this shouldn't happen
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*
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* The trouble is, letting people know about this is not really
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* possible, since we are currently running incoherently, and
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* therefore cannot safely call printk() or anything else
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*/
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pr_debug("CPU%u: spurious wakeup call\n", cpu);
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}
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}
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int platform_cpu_kill(unsigned int cpu)
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{
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return 1;
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}
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/*
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* platform-specific code to shutdown a CPU
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*
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* Called with IRQs disabled
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*/
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void platform_cpu_die(unsigned int cpu)
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{
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/*
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* we're ready for shutdown now, so do it
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*/
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cpu_enter_lowpower();
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platform_do_lowpower(cpu);
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/*
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* bring this CPU back into the world of cache
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* coherency, and then restore interrupts
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*/
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cpu_leave_lowpower();
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}
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int platform_cpu_disable(unsigned int cpu)
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{
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/*
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* we don't allow CPU 0 to be shutdown (it is still too special
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* e.g. clock tick interrupts)
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*/
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return cpu == 0 ? -EPERM : 0;
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}
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