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Thomas Gleixner45051532019-05-29 16:57:47 -07001// SPDX-License-Identifier: GPL-2.0-only
Catalin Marinasd7f864b2008-04-18 22:43:06 +01002/*
3 * arch/arm/kernel/thumbee.c
4 *
5 * Copyright (C) 2008 ARM Limited
Catalin Marinasd7f864b2008-04-18 22:43:06 +01006 */
7
8#include <linux/kernel.h>
9#include <linux/init.h>
10
Jonathan Austin58834ee2012-04-12 17:52:10 +010011#include <asm/cputype.h>
David Howells9f97da72012-03-28 18:30:01 +010012#include <asm/system_info.h>
Catalin Marinasd7f864b2008-04-18 22:43:06 +010013#include <asm/thread_notify.h>
14
15/*
16 * Access to the ThumbEE Handler Base register
17 */
Catalin Marinas7f1fd312008-11-10 14:14:11 +000018static inline unsigned long teehbr_read(void)
Catalin Marinasd7f864b2008-04-18 22:43:06 +010019{
20 unsigned long v;
21 asm("mrc p14, 6, %0, c1, c0, 0\n" : "=r" (v));
22 return v;
23}
24
25static inline void teehbr_write(unsigned long v)
26{
27 asm("mcr p14, 6, %0, c1, c0, 0\n" : : "r" (v));
28}
29
30static int thumbee_notifier(struct notifier_block *self, unsigned long cmd, void *t)
31{
32 struct thread_info *thread = t;
33
34 switch (cmd) {
35 case THREAD_NOTIFY_FLUSH:
Nathan Lynchfbfb8722014-09-11 02:49:08 +010036 teehbr_write(0);
Catalin Marinasd7f864b2008-04-18 22:43:06 +010037 break;
38 case THREAD_NOTIFY_SWITCH:
39 current_thread_info()->thumbee_state = teehbr_read();
40 teehbr_write(thread->thumbee_state);
41 break;
42 }
43
44 return NOTIFY_DONE;
45}
46
47static struct notifier_block thumbee_notifier_block = {
48 .notifier_call = thumbee_notifier,
49};
50
51static int __init thumbee_init(void)
52{
53 unsigned long pfr0;
54 unsigned int cpu_arch = cpu_architecture();
55
56 if (cpu_arch < CPU_ARCH_ARMv7)
57 return 0;
58
Jonathan Austin58834ee2012-04-12 17:52:10 +010059 pfr0 = read_cpuid_ext(CPUID_EXT_PFR0);
Catalin Marinasd7f864b2008-04-18 22:43:06 +010060 if ((pfr0 & 0x0000f000) != 0x00001000)
61 return 0;
62
Russell King4ed89f22014-10-28 11:26:42 +000063 pr_info("ThumbEE CPU extension supported.\n");
Catalin Marinasd7f864b2008-04-18 22:43:06 +010064 elf_hwcap |= HWCAP_THUMBEE;
65 thread_register_notifier(&thumbee_notifier_block);
66
67 return 0;
68}
69
70late_initcall(thumbee_init);