1 /* SPDX-License-Identifier: GPL-2.0+ */
3 * Routines to access the system control register
5 * Copyright (c) 2019 Heinrich Schuchardt
8 #include <linux/linkage.h>
11 * void allow_unaligned(void) - allow unaligned access
13 * This routine sets the enable unaligned data support flag and clears the
14 * aligned flag in the system control register.
15 * After calling this routine unaligned access does no longer leads to a
16 * data abort or undefined behavior but is handled by the CPU.
17 * For details see the "ARM Architecture Reference Manual" for ARMv6.
19 ENTRY(allow_unaligned)
20 mrc p15, 0, r0, c1, c0, 0 @ load system control register
21 orr r0, r0, #1 << 22 @ set unaligned data support flag
22 bic r0, r0, #2 @ clear aligned flag
23 mcr p15, 0, r0, c1, c0, 0 @ write system control register
25 ENDPROC(allow_unaligned)