Commit 8164f7af authored by Stephen Boyd's avatar Stephen Boyd Committed by Russell King
Browse files

ARM: 7680/1: Detect support for SDIV/UDIV from ISAR0 register 



The ISAR0 register indicates support for the SDIV and UDIV
instructions in both the Thumb and ARM instruction set. Read the
register to detect the supported instructions and update the
elf_hwcap mask as appropriate. This is better than adding more
and more cpuid checks in proc-v7.S for each new cpu variant that
supports these instructions.

Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Cc: Stepan Moskovchenko <stepanm@codeaurora.org>
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent c40e3641

arch/arm/kernel/setup.c

+20 −0
Original line number Diff line number Diff line
@@ -353,6 +353,23 @@ void __init early_print(const char *str, ...) 
	printk("%s", buf);

}



static void __init cpuid_init_hwcaps(void)

{

	unsigned int divide_instrs;



	if (cpu_architecture() < CPU_ARCH_ARMv7)

		return;



	divide_instrs = (read_cpuid_ext(CPUID_EXT_ISAR0) & 0x0f000000) >> 24;



	switch (divide_instrs) {

	case 2:

		elf_hwcap |= HWCAP_IDIVA;

	case 1:

		elf_hwcap |= HWCAP_IDIVT;

	}

}



static void __init feat_v6_fixup(void)

{

	int id = read_cpuid_id();
@@ -483,6 +500,9 @@ static void __init setup_processor(void) 
	snprintf(elf_platform, ELF_PLATFORM_SIZE, "%s%c",

		 list->elf_name, ENDIANNESS);

	elf_hwcap = list->elf_hwcap;



	cpuid_init_hwcaps();



#ifndef CONFIG_ARM_THUMB

	elf_hwcap &= ~(HWCAP_THUMB | HWCAP_IDIVT);

#endif

arch/arm/mm/proc-v7.S

+2 −2
Original line number Diff line number Diff line
@@ -420,7 +420,7 @@ __v7_pj4b_proc_info: 
__v7_ca7mp_proc_info:

	.long	0x410fc070

	.long	0xff0ffff0

	__v7_proc __v7_ca7mp_setup, hwcaps = HWCAP_IDIV

	__v7_proc __v7_ca7mp_setup

	.size	__v7_ca7mp_proc_info, . - __v7_ca7mp_proc_info



	/*
@@ -430,7 +430,7 @@ __v7_ca7mp_proc_info: 
__v7_ca15mp_proc_info:

	.long	0x410fc0f0

	.long	0xff0ffff0

	__v7_proc __v7_ca15mp_setup, hwcaps = HWCAP_IDIV

	__v7_proc __v7_ca15mp_setup

	.size	__v7_ca15mp_proc_info, . - __v7_ca15mp_proc_info



	/*

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