1 files changed, 76 insertions, 0 deletions
diff --git a/arch/arm/include/asm/sysreg.h b/arch/arm/include/asm/sysreg.h
new file mode 100644
index 0000000000..7d567e08d8
--- /dev/null
+++ b/arch/arm/include/asm/sysreg.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Macros for accessing system registers with older binutils.
+ *
+ * Copyright (C) 2014 ARM Ltd.
+ * Author: Catalin Marinas <catalin.marinas@arm.com>
+ */
+
+#ifndef __ASM_SYSREG_H
+#define __ASM_SYSREG_H
+
+#include <asm/system.h>
+#include <linux/stringify.h>
+
+/*
+ * Unlike read_cpuid, calls to read_sysreg are never expected to be
+ * optimized away or replaced with synthetic values.
+ */
+#define read_sysreg(r) ({					\
+	u64 __val;						\
+	asm volatile("mrs %0, " __stringify(r) : "=r" (__val));	\
+	__val;							\
+})
+
+/*
+ * The "Z" constraint normally means a zero immediate, but when combined with
+ * the "%x0" template means XZR.
+ */
+#define write_sysreg(v, r) do {					\
+	u64 __val = (u64)(v);					\
+	asm volatile("msr " __stringify(r) ", %x0"		\
+		     : : "rZ" (__val));				\
+} while (0)
+
+/*
+ * For registers without architectural names, or simply unsupported by
+ * GAS.
+ */
+#define read_sysreg_s(r) ({						\
+	u64 __val;							\
+	asm volatile(__mrs_s("%0", r) : "=r" (__val));			\
+	__val;								\
+})
+
+#define write_sysreg_s(v, r) do {					\
+	u64 __val = (u64)(v);						\
+	asm volatile(__msr_s(r, "%x0") : : "rZ" (__val));		\
+} while (0)
+
+/*
+ * Modify bits in a sysreg. Bits in the clear mask are zeroed, then bits in the
+ * set mask are set. Other bits are left as-is.
+ */
+#define sysreg_clear_set(sysreg, clear, set) do {			\
+	u64 __scs_val = read_sysreg(sysreg);				\
+	u64 __scs_new = (__scs_val & ~(u64)(clear)) | (set);		\
+	if (__scs_new != __scs_val)					\
+		write_sysreg(__scs_new, sysreg);			\
+} while (0)
+
+#define sysreg_clear_set_s(sysreg, clear, set) do {			\
+	u64 __scs_val = read_sysreg_s(sysreg);				\
+	u64 __scs_new = (__scs_val & ~(u64)(clear)) | (set);		\
+	if (__scs_new != __scs_val)					\
+		write_sysreg_s(__scs_new, sysreg);			\
+} while (0)
+
+#define read_sysreg_par() ({						\
+	u64 par;							\
+	asm("dmb sy");							\
+	par = read_sysreg(par_el1);					\
+	asm("dmb sy");							\
+	par;								\
+})
+
+#endif	/* __ASM_SYSREG_H */