| 1 | |
| 2 | |
| 3 | * arch/arm/kernel/thumbee.c
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| 4 | *
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| 5 | * Copyright (C) 2008 ARM Limited
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| 6 |
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| 7 |
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| 8 | #include <linux/kernel.h>
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| 9 | #include <linux/init.h>
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| 10 |
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| 11 | #include <asm/cputype.h>
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| 12 | #include <asm/system_info.h>
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| 13 | #include <asm/thread_notify.h>
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| 14 |
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| 15 | |
| 16 | * Access to the ThumbEE Handler Base register
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| 17 |
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| 18 | static inline unsigned long teehbr_read(void)
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| 19 | {
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| 20 | unsigned long v;
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| 21 | asm("mrc p14, 6, %0, c1, c0, 0\n" : "=r" (v));
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| 22 | return v;
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| 23 | }
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| 24 |
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| 25 | static inline void teehbr_write(unsigned long v)
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| 26 | {
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| 27 | asm("mcr p14, 6, %0, c1, c0, 0\n" : : "r" (v));
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| 28 | }
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| 29 |
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| 30 | static int thumbee_notifier(struct notifier_block *self, unsigned long cmd, void *t)
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| 31 | {
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| 32 | struct thread_info *thread = t;
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| 33 |
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| 34 | switch (cmd) {
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| 35 | case THREAD_NOTIFY_FLUSH:
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| 36 | teehbr_write(0);
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| 37 | break;
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| 38 | case THREAD_NOTIFY_SWITCH:
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| 39 | current_thread_info()->thumbee_state = teehbr_read();
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| 40 | teehbr_write(thread->thumbee_state);
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| 41 | break;
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| 42 | }
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| 43 |
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| 44 | return NOTIFY_DONE;
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| 45 | }
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| 46 |
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| 47 | static struct notifier_block thumbee_notifier_block = {
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| 48 | .notifier_call = thumbee_notifier,
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| 49 | };
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| 50 |
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| 51 | static int __init thumbee_init(void)
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| 52 | {
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| 53 | unsigned long pfr0;
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| 54 | unsigned int cpu_arch = cpu_architecture();
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| 55 |
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| 56 | if (cpu_arch < CPU_ARCH_ARMv7)
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| 57 | return 0;
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| 58 |
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| 59 | pfr0 = read_cpuid_ext(CPUID_EXT_PFR0);
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| 60 | if ((pfr0 & 0x0000f000) != 0x00001000)
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| 61 | return 0;
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| 62 |
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| 63 | pr_info("ThumbEE CPU extension supported.\n");
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| 64 | elf_hwcap |= HWCAP_THUMBEE;
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| 65 | thread_register_notifier(&thumbee_notifier_block);
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| 66 |
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| 67 | return 0;
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| 68 | }
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| 69 |
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| 70 | late_initcall(thumbee_init);
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