GK SDK 源码库: XMIPCLinuxV100R005C00SPC030 (kernel/tools/open_source excluded)

2026-09-06 03:52:57 +08:00
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+/* SPDX-License-Identifier:	GPL-2.0+ */
+/*
+ *  Routines to access the system control register
+ *
+ *  Copyright (c) 2019 Heinrich Schuchardt
+ */
+
+#include <linux/linkage.h>
+
+/*
+ * void allow_unaligned(void) - allow unaligned access
+ *
+ * This routine sets the enable unaligned data support flag and clears the
+ * aligned flag in the system control register.
+ * After calling this routine unaligned access does no longer leads to a
+ * data abort or undefined behavior but is handled by the CPU.
+ * For details see the "ARM Architecture Reference Manual" for ARMv6.
+ */
+ENTRY(allow_unaligned)
+	mrc	p15, 0, r0, c1, c0, 0	@ load system control register
+	orr	r0, r0, #1 << 22	@ set unaligned data support flag
+	bic	r0, r0, #2		@ clear aligned flag
+	mcr	p15, 0, r0, c1, c0, 0	@ write system control register
+	bx	lr			@ return
+ENDPROC(allow_unaligned)