arm/arm64: add some delay routines

Allow a thread to wait some specified amount of time. Can specify in cycles, usecs, and msecs. Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Andrew Jones <drjones@redhat.com>
rhdrjones · Jul 15, 2016 · 40f1d91 · 40f1d91
1 parent 264fbe8
commit 40f1d91
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diff --git a/lib/arm/asm/processor.h b/lib/arm/asm/processor.h
@@ -5,7 +5,9 @@
  *
  * This work is licensed under the terms of the GNU LGPL, version 2.
  */
+#include <libcflat.h>
 #include <asm/ptrace.h>
+#include <asm/barrier.h>
 
 enum vector {
 	EXCPTN_RST,
@@ -51,4 +53,21 @@ extern int mpidr_to_cpu(unsigned long mpidr);
 extern void start_usr(void (*func)(void *arg), void *arg, unsigned long sp_usr);
 extern bool is_user(void);
 
+static inline u64 get_cntvct(void)
+{
+	u64 vct;
+	isb();
+	asm volatile("mrrc p15, 1, %Q0, %R0, c14" : "=r" (vct));
+	return vct;
+}
+
+extern void delay(u64 cycles);
+extern void udelay(unsigned long usecs);
+
+static inline void mdelay(unsigned long msecs)
+{
+	while (msecs--)
+		udelay(1000);
+}
+
 #endif /* _ASMARM_PROCESSOR_H_ */
diff --git a/lib/arm/processor.c b/lib/arm/processor.c
@@ -9,6 +9,7 @@
 #include <asm/ptrace.h>
 #include <asm/processor.h>
 #include <asm/thread_info.h>
+#include <asm/barrier.h>
 
 static const char *processor_modes[] = {
 	"USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" ,
@@ -141,3 +142,17 @@ bool is_user(void)
 {
 	return current_thread_info()->flags & TIF_USER_MODE;
 }
+
+void delay(u64 cycles)
+{
+	u64 start = get_cntvct();
+	while ((get_cntvct() - start) < cycles)
+		cpu_relax();
+}
+
+void udelay(unsigned long usec)
+{
+	unsigned int frq;
+	asm volatile("mrc p15, 0, %0, c14, c0, 0" : "=r" (frq));
+	delay((u64)usec * frq / 1000000);
+}
diff --git a/lib/arm64/asm/processor.h b/lib/arm64/asm/processor.h
@@ -17,8 +17,10 @@
 #define SCTLR_EL1_M	(1 << 0)
 
 #ifndef __ASSEMBLY__
+#include <libcflat.h>
 #include <asm/ptrace.h>
 #include <asm/esr.h>
+#include <asm/barrier.h>
 
 enum vector {
 	EL1T_SYNC,
@@ -89,5 +91,22 @@ extern int mpidr_to_cpu(unsigned long mpidr);
 extern void start_usr(void (*func)(void *arg), void *arg, unsigned long sp_usr);
 extern bool is_user(void);
 
+static inline u64 get_cntvct(void)
+{
+	u64 vct;
+	isb();
+	asm volatile("mrs %0, cntvct_el0" : "=r" (vct));
+	return vct;
+}
+
+extern void delay(u64 cycles);
+extern void udelay(unsigned long usecs);
+
+static inline void mdelay(unsigned long msecs)
+{
+	while (msecs--)
+		udelay(1000);
+}
+
 #endif /* !__ASSEMBLY__ */
 #endif /* _ASMARM64_PROCESSOR_H_ */
diff --git a/lib/arm64/processor.c b/lib/arm64/processor.c
@@ -9,6 +9,7 @@
 #include <asm/ptrace.h>
 #include <asm/processor.h>
 #include <asm/thread_info.h>
+#include <asm/barrier.h>
 
 static const char *vector_names[] = {
 	"el1t_sync",
@@ -253,3 +254,17 @@ bool is_user(void)
 {
 	return current_thread_info()->flags & TIF_USER_MODE;
 }
+
+void delay(u64 cycles)
+{
+	u64 start = get_cntvct();
+	while ((get_cntvct() - start) < cycles)
+		cpu_relax();
+}
+
+void udelay(unsigned long usec)
+{
+	unsigned int frq;
+	asm volatile("mrs %0, cntfrq_el0" : "=r" (frq));
+	delay((u64)usec * frq / 1000000);
+}