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 */
28 static inline unsigned long teehbr_read(void)
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);
82
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