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d7f864be CM |
1 | /* |
2 | * arch/arm/kernel/thumbee.c | |
3 | * | |
4 | * Copyright (C) 2008 ARM Limited | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License | |
16 | * along with this program; if not, write to the Free Software | |
17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
18 | */ | |
19 | ||
20 | #include <linux/kernel.h> | |
21 | #include <linux/init.h> | |
22 | ||
23 | #include <asm/thread_notify.h> | |
24 | ||
25 | /* | |
26 | * Access to the ThumbEE Handler Base register | |
27 | */ | |
7f1fd31d | 28 | static inline unsigned long teehbr_read(void) |
d7f864be CM |
29 | { |
30 | unsigned long v; | |
31 | asm("mrc p14, 6, %0, c1, c0, 0\n" : "=r" (v)); | |
32 | return v; | |
33 | } | |
34 | ||
35 | static inline void teehbr_write(unsigned long v) | |
36 | { | |
37 | asm("mcr p14, 6, %0, c1, c0, 0\n" : : "r" (v)); | |
38 | } | |
39 | ||
40 | static int thumbee_notifier(struct notifier_block *self, unsigned long cmd, void *t) | |
41 | { | |
42 | struct thread_info *thread = t; | |
43 | ||
44 | switch (cmd) { | |
45 | case THREAD_NOTIFY_FLUSH: | |
46 | thread->thumbee_state = 0; | |
47 | break; | |
48 | case THREAD_NOTIFY_SWITCH: | |
49 | current_thread_info()->thumbee_state = teehbr_read(); | |
50 | teehbr_write(thread->thumbee_state); | |
51 | break; | |
52 | } | |
53 | ||
54 | return NOTIFY_DONE; | |
55 | } | |
56 | ||
57 | static struct notifier_block thumbee_notifier_block = { | |
58 | .notifier_call = thumbee_notifier, | |
59 | }; | |
60 | ||
61 | static int __init thumbee_init(void) | |
62 | { | |
63 | unsigned long pfr0; | |
64 | unsigned int cpu_arch = cpu_architecture(); | |
65 | ||
66 | if (cpu_arch < CPU_ARCH_ARMv7) | |
67 | return 0; | |
68 | ||
69 | /* processor feature register 0 */ | |
70 | asm("mrc p15, 0, %0, c0, c1, 0\n" : "=r" (pfr0)); | |
71 | if ((pfr0 & 0x0000f000) != 0x00001000) | |
72 | return 0; | |
73 | ||
74 | printk(KERN_INFO "ThumbEE CPU extension supported.\n"); | |
75 | elf_hwcap |= HWCAP_THUMBEE; | |
76 | thread_register_notifier(&thumbee_notifier_block); | |
77 | ||
78 | return 0; | |
79 | } | |
80 | ||
81 | late_initcall(thumbee_init); |