/*
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* Disable Intel automatic promotion to C1E mode.
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* Lifted from drivers/idle/intel_idle.c
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* Copyright (c) 2013, Intel Corporation.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include <linux/smp.h>
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#include <asm/processor.h>
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#include <asm/cpu_device_id.h>
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#include <asm/msr.h>
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#define ICPU(model) \
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{ X86_VENDOR_INTEL, 6, model, X86_FEATURE_MWAIT, 1UL }
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static const struct x86_cpu_id c1e_ids[] = {
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ICPU(0x1a),
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ICPU(0x1e),
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ICPU(0x1f),
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ICPU(0x25),
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ICPU(0x2c),
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ICPU(0x2e),
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ICPU(0x2f),
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ICPU(0x2a),
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ICPU(0x2d),
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ICPU(0x3a),
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ICPU(0x3e),
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ICPU(0x3c),
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ICPU(0x3f),
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ICPU(0x45),
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ICPU(0x46),
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ICPU(0x4D),
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{}
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};
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#undef ICPU
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static void c1e_promotion_disable(void *dummy)
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{
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unsigned long long msr_bits;
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rdmsrl(MSR_IA32_POWER_CTL, msr_bits);
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msr_bits &= ~0x2;
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wrmsrl(MSR_IA32_POWER_CTL, msr_bits);
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}
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void mach_x86_c1e_disable(void)
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{
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const struct x86_cpu_id *id;
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id = x86_match_cpu(c1e_ids);
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if (id) {
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printk("[Xenomai] disabling automatic C1E state promotion on Intel processor\n");
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/*
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* cpu uses C1E, disable this feature (copied from
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* intel_idle driver)
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*/
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on_each_cpu(c1e_promotion_disable, NULL, 1);
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}
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}
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