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

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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: Will Deacon <will.deacon@arm.com>
Cc: Stepan Moskovchenko <stepanm@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Stephen Boyd
2013-03-18 19:44:15 +01:00
committed by Russell King
parent c40e364167
commit 8164f7af88
2 changed files with 22 additions and 2 deletions
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20
arch/arm/kernel/setup.c
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@@ -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