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authorJesper Nilsson <jesper.nilsson@axis.com>2008-01-25 19:31:38 +0300
committerJesper Nilsson <jesper.nilsson@axis.com>2008-02-08 13:06:35 +0300
commit48c87a4483d9146d9f23198163d6ee621535702d (patch)
tree1499bd32160b41a5524ee8b44adf41df35fa37ba /arch/cris
parenta474de0a02ee9093af96414a30f69d433201d002 (diff)
downloadlinux-48c87a4483d9146d9f23198163d6ee621535702d.tar.xz
CRIS v32: Add precise delay loops for ETRAX FS and ARTPEC-3.
Implements cris_delay10ns.
Diffstat (limited to 'arch/cris')
-rw-r--r--arch/cris/arch-v32/lib/delay.c28
1 files changed, 28 insertions, 0 deletions
diff --git a/arch/cris/arch-v32/lib/delay.c b/arch/cris/arch-v32/lib/delay.c
new file mode 100644
index 000000000000..39f1ac9995b4
--- /dev/null
+++ b/arch/cris/arch-v32/lib/delay.c
@@ -0,0 +1,28 @@
+/*
+ * Precise Delay Loops for ETRAX FS
+ *
+ * Copyright (C) 2006 Axis Communications AB.
+ *
+ */
+
+#include <hwregs/reg_map.h>
+#include <hwregs/reg_rdwr.h>
+#include <hwregs/timer_defs.h>
+#include <linux/types.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+
+/*
+ * On ETRAX FS, we can check the free-running read-only 100MHz timer
+ * getting 32-bit 10ns precision, theoretically good for 42.94967295
+ * seconds. Unsigned arithmetic and careful expression handles
+ * wrapping.
+ */
+
+void cris_delay10ns(u32 n10ns)
+{
+ u32 t0 = REG_RD(timer, regi_timer0, r_time);
+ while (REG_RD(timer, regi_timer0, r_time) - t0 < n10ns)
+ ;
+}
+EXPORT_SYMBOL(cris_delay10ns);