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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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292ec42af7
Add a function to set the SCU low-power mode for SMP CPUs. This centralizes this functionality rather than having to expose the SCU register definitions to each platform. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
76 lines
1.7 KiB
C
76 lines
1.7 KiB
C
/*
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* linux/arch/arm/kernel/smp_scu.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/io.h>
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#include <asm/smp_scu.h>
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#include <asm/cacheflush.h>
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#define SCU_CTRL 0x00
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#define SCU_CONFIG 0x04
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#define SCU_CPU_STATUS 0x08
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#define SCU_INVALIDATE 0x0c
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#define SCU_FPGA_REVISION 0x10
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/*
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* Get the number of CPU cores from the SCU configuration
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*/
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unsigned int __init scu_get_core_count(void __iomem *scu_base)
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{
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unsigned int ncores = __raw_readl(scu_base + SCU_CONFIG);
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return (ncores & 0x03) + 1;
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}
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/*
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* Enable the SCU
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*/
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void __init scu_enable(void __iomem *scu_base)
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{
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u32 scu_ctrl;
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scu_ctrl = __raw_readl(scu_base + SCU_CTRL);
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/* already enabled? */
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if (scu_ctrl & 1)
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return;
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scu_ctrl |= 1;
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__raw_writel(scu_ctrl, scu_base + SCU_CTRL);
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/*
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* Ensure that the data accessed by CPU0 before the SCU was
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* initialised is visible to the other CPUs.
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*/
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flush_cache_all();
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}
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/*
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* Set the executing CPUs power mode as defined. This will be in
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* preparation for it executing a WFI instruction.
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*
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* This function must be called with preemption disabled, and as it
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* has the side effect of disabling coherency, caches must have been
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* flushed. Interrupts must also have been disabled.
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*/
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int scu_power_mode(void __iomem *scu_base, unsigned int mode)
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{
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unsigned int val;
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int cpu = smp_processor_id();
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if (mode > 3 || mode == 1 || cpu > 3)
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return -EINVAL;
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val = __raw_readb(scu_base + SCU_CPU_STATUS + cpu) & ~0x03;
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val |= mode;
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__raw_writeb(val, scu_base + SCU_CPU_STATUS + cpu);
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return 0;
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}
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