ARM: 8306/1: loop_udelay: remove bogomips value limitation
Now that we don't support ARMv3 anymore, the loop based delay code can
convert microsecs into number of loops using a 64-bit multiplication
and more precision.
This allows us to lift the hard limit of 3355 on the bogomips value as
loops_per_jiffy may now safely span the full 32-bit range.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/include/asm/delay.h b/arch/arm/include/asm/delay.h
index dff714d..b7a4281 100644
--- a/arch/arm/include/asm/delay.h
+++ b/arch/arm/include/asm/delay.h
@@ -10,8 +10,8 @@
#include <asm/param.h> /* HZ */
#define MAX_UDELAY_MS 2
-#define UDELAY_MULT ((UL(2199023) * HZ) >> 11)
-#define UDELAY_SHIFT 30
+#define UDELAY_MULT UL(2047 * HZ + 483648 * HZ / 1000000)
+#define UDELAY_SHIFT 31
#ifndef __ASSEMBLY__
@@ -34,7 +34,7 @@
* it, it means that you're calling udelay() with an out of range value.
*
* With currently imposed limits, this means that we support a max delay
- * of 2000us. Further limits: HZ<=1000 and bogomips<=3355
+ * of 2000us. Further limits: HZ<=1000
*/
extern void __bad_udelay(void);
diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile
index d8a7807..27f4d962 100644
--- a/arch/arm/lib/Makefile
+++ b/arch/arm/lib/Makefile
@@ -29,7 +29,10 @@
lib-y += io-readsw-armv4.o io-writesw-armv4.o
endif
-lib-$(CONFIG_ARCH_RPC) += ecard.o io-acorn.o floppydma.o
+ifeq ($(CONFIG_ARCH_RPC),y)
+ lib-y += ecard.o io-acorn.o floppydma.o
+ AFLAGS_delay-loop.o += -march=armv4
+endif
$(obj)/csumpartialcopy.o: $(obj)/csumpartialcopygeneric.S
$(obj)/csumpartialcopyuser.o: $(obj)/csumpartialcopygeneric.S
diff --git a/arch/arm/lib/delay-loop.S b/arch/arm/lib/delay-loop.S
index 518bf6e..792c59d 100644
--- a/arch/arm/lib/delay-loop.S
+++ b/arch/arm/lib/delay-loop.S
@@ -10,6 +10,7 @@
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/delay.h>
+
.text
.LC0: .word loops_per_jiffy
@@ -17,7 +18,6 @@
/*
* r0 <= 2000
- * lpj <= 0x01ffffff (max. 3355 bogomips)
* HZ <= 1000
*/
@@ -25,16 +25,11 @@
ldr r2, .LC1
mul r0, r2, r0
ENTRY(__loop_const_udelay) @ 0 <= r0 <= 0x7fffff06
- mov r1, #-1
ldr r2, .LC0
- ldr r2, [r2] @ max = 0x01ffffff
- add r0, r0, r1, lsr #32-14
- mov r0, r0, lsr #14 @ max = 0x0001ffff
- add r2, r2, r1, lsr #32-10
- mov r2, r2, lsr #10 @ max = 0x00007fff
- mul r0, r2, r0 @ max = 2^32-1
- add r0, r0, r1, lsr #32-6
- movs r0, r0, lsr #6
+ ldr r2, [r2]
+ umull r1, r0, r2, r0
+ adds r1, r1, #0xffffffff
+ adcs r0, r0, r0
reteq lr
/*