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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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105 lines
2.2 KiB
C
105 lines
2.2 KiB
C
/*
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* Copyright (C) 2012-2013 Xilinx
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*
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* based on linux/arch/arm/mach-realview/hotplug.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/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/cp15.h>
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#include "common.h"
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static inline void zynq_cpu_enter_lowpower(void)
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{
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unsigned int v;
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flush_cache_all();
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asm volatile(
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" mcr p15, 0, %1, c7, c5, 0\n"
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" dsb\n"
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/*
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* Turn off coherency
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*/
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" mrc p15, 0, %0, c1, c0, 1\n"
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" bic %0, %0, #0x40\n"
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" mcr p15, 0, %0, c1, c0, 1\n"
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" mrc p15, 0, %0, c1, c0, 0\n"
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" bic %0, %0, %2\n"
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" mcr p15, 0, %0, c1, c0, 0\n"
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: "=&r" (v)
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: "r" (0), "Ir" (CR_C)
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: "cc");
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}
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static inline void zynq_cpu_leave_lowpower(void)
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{
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unsigned int v;
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asm volatile(
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" mrc p15, 0, %0, c1, c0, 0\n"
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" orr %0, %0, %1\n"
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" mcr p15, 0, %0, c1, c0, 0\n"
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" mrc p15, 0, %0, c1, c0, 1\n"
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" orr %0, %0, #0x40\n"
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" mcr p15, 0, %0, c1, c0, 1\n"
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: "=&r" (v)
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: "Ir" (CR_C)
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: "cc");
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}
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static inline void zynq_platform_do_lowpower(unsigned int cpu, int *spurious)
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{
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/*
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* there is no power-control hardware on this platform, so all
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* we can do is put the core into WFI; this is safe as the calling
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* code will have already disabled interrupts
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*/
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for (;;) {
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dsb();
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wfi();
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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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* Just note it happening - when we're woken, we can report
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* its occurrence.
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*/
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(*spurious)++;
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}
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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 zynq_platform_cpu_die(unsigned int cpu)
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{
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int spurious = 0;
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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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zynq_cpu_enter_lowpower();
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zynq_platform_do_lowpower(cpu, &spurious);
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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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zynq_cpu_leave_lowpower();
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if (spurious)
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pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
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}
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