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| author | Nicolas Pitre <nicolas.pitre@linaro.org> | 2015-02-25 22:50:39 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@armlinux.org.uk> | 2016-06-22 19:55:12 +0100 |
| commit | 215e362dafede7cc691d8a573d2b31bc7138a770 (patch) | |
| tree | 0d74459f20b700a50e6f3e637d5f8a017e3aecfd /arch/arm | |
| parent | 2374b063c3dfbb68a40b52067eaff81510f384b1 (diff) | |
| download | blackbird-op-linux-215e362dafede7cc691d8a573d2b31bc7138a770.tar.gz blackbird-op-linux-215e362dafede7cc691d8a573d2b31bc7138a770.zip | |
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>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/include/asm/delay.h | 6 | ||||
| -rw-r--r-- | arch/arm/lib/Makefile | 5 | ||||
| -rw-r--r-- | arch/arm/lib/delay-loop.S | 15 |
3 files changed, 12 insertions, 14 deletions
diff --git a/arch/arm/include/asm/delay.h b/arch/arm/include/asm/delay.h index dff714d886d5..b7a428154355 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 @@ extern struct arm_delay_ops { * 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 d8a780799506..27f4d96258a2 100644 --- a/arch/arm/lib/Makefile +++ b/arch/arm/lib/Makefile @@ -29,7 +29,10 @@ else 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 518bf6e93f78..792c59d885bc 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 @@ ENTRY(__loop_udelay) 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 /* |
