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70 lines
1.4 KiB
70 lines
1.4 KiB
// 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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