// SPDX-License-Identifier: GPL-2.0-only
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/*
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* arch/arm/kernel/thumbee.c
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*
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* Copyright (C) 2008 ARM Limited
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <asm/cputype.h>
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#include <asm/system_info.h>
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#include <asm/thread_notify.h>
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/*
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* Access to the ThumbEE Handler Base register
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*/
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static inline unsigned long teehbr_read(void)
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{
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unsigned long v;
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asm("mrc p14, 6, %0, c1, c0, 0\n" : "=r" (v));
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return v;
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}
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static inline void teehbr_write(unsigned long v)
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{
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asm("mcr p14, 6, %0, c1, c0, 0\n" : : "r" (v));
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}
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static int thumbee_notifier(struct notifier_block *self, unsigned long cmd, void *t)
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{
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struct thread_info *thread = t;
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switch (cmd) {
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case THREAD_NOTIFY_FLUSH:
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teehbr_write(0);
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break;
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case THREAD_NOTIFY_SWITCH:
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current_thread_info()->thumbee_state = teehbr_read();
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teehbr_write(thread->thumbee_state);
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break;
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}
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return NOTIFY_DONE;
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}
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static struct notifier_block thumbee_notifier_block = {
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.notifier_call = thumbee_notifier,
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};
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static int __init thumbee_init(void)
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{
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unsigned long pfr0;
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unsigned int cpu_arch = cpu_architecture();
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if (cpu_arch < CPU_ARCH_ARMv7)
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return 0;
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pfr0 = read_cpuid_ext(CPUID_EXT_PFR0);
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if ((pfr0 & 0x0000f000) != 0x00001000)
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return 0;
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pr_info("ThumbEE CPU extension supported.\n");
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elf_hwcap |= HWCAP_THUMBEE;
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thread_register_notifier(&thumbee_notifier_block);
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return 0;
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}
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late_initcall(thumbee_init);
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