Commit 5aaf2544 authored by Tony Lindgren's avatar Tony Lindgren Committed by Russell King
Browse files

ARM: 6203/1: Make VFPv3 usable on ARMv6 



MVFR0 and MVFR1 are only available starting with ARM1136 r1p0 release
according to "B.5 VFP changes" in DDI0211F_arm1136_r1p0_trm.pdf. This is
also when TLS register got added, so we can use HAS_TLS also to test for
MVFR0 and MVFR1.

Otherwise VFPFMRX and VFPFMXR access fails and we get:

Internal error: Oops - undefined instruction: 0 [#1]
PC is at no_old_VFP_process+0x8/0x3c
LR is at __und_svc+0x48/0x80
...

Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent e513f8bf

arch/arm/include/asm/vfpmacros.h

+18 −0
Original line number Diff line number Diff line
@@ -3,6 +3,8 @@ 
 *

 * Assembler-only file containing VFP macros and register definitions.

 */

#include <asm/hwcap.h>



#include "vfp.h"



@ Macros to allow building with old toolkits (with no VFP support)
@@ -22,11 +24,19 @@ 
	LDC	p11, cr0, [\base],#32*4		    @ FLDMIAD \base!, {d0-d15}

#endif

#ifdef CONFIG_VFPv3

#if __LINUX_ARM_ARCH__ <= 6

	ldr	\tmp, =elf_hwcap		    @ may not have MVFR regs

	ldr	\tmp, [\tmp, #0]

	tst	\tmp, #HWCAP_VFPv3D16

	ldceq	p11, cr0, [\base],#32*4		    @ FLDMIAD \base!, {d16-d31}

	addne	\base, \base, #32*4		    @ step over unused register space

#else

	VFPFMRX	\tmp, MVFR0			    @ Media and VFP Feature Register 0

	and	\tmp, \tmp, #MVFR0_A_SIMD_MASK	    @ A_SIMD field

	cmp	\tmp, #2			    @ 32 x 64bit registers?

	ldceql	p11, cr0, [\base],#32*4		    @ FLDMIAD \base!, {d16-d31}

	addne	\base, \base, #32*4		    @ step over unused register space

#endif

#endif

	.endm
@@ -38,10 +48,18 @@ 
	STC	p11, cr0, [\base],#32*4		    @ FSTMIAD \base!, {d0-d15}

#endif

#ifdef CONFIG_VFPv3

#if __LINUX_ARM_ARCH__ <= 6

	ldr	\tmp, =elf_hwcap		    @ may not have MVFR regs

	ldr	\tmp, [\tmp, #0]

	tst	\tmp, #HWCAP_VFPv3D16

	stceq	p11, cr0, [\base],#32*4		    @ FSTMIAD \base!, {d16-d31}

	addne	\base, \base, #32*4		    @ step over unused register space

#else

	VFPFMRX	\tmp, MVFR0			    @ Media and VFP Feature Register 0

	and	\tmp, \tmp, #MVFR0_A_SIMD_MASK	    @ A_SIMD field

	cmp	\tmp, #2			    @ 32 x 64bit registers?

	stceql	p11, cr0, [\base],#32*4		    @ FSTMIAD \base!, {d16-d31}

	addne	\base, \base, #32*4		    @ step over unused register space

#endif

#endif

	.endm

arch/arm/vfp/vfpmodule.c

+7 −3
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <linux/sched.h>

#include <linux/init.h>



#include <asm/cputype.h>

#include <asm/thread_notify.h>

#include <asm/vfp.h>
@@ -549,10 +550,13 @@ static int __init vfp_init(void) 
		/*

		 * Check for the presence of the Advanced SIMD

		 * load/store instructions, integer and single

		 * precision floating point operations.

		 * precision floating point operations. Only check

		 * for NEON if the hardware has the MVFR registers.

		 */

		if ((read_cpuid_id() & 0x000f0000) == 0x000f0000) {

			if ((fmrx(MVFR1) & 0x000fff00) == 0x00011100)

				elf_hwcap |= HWCAP_NEON;

		}

#endif

	}

	return 0;

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