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: 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>
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index e2c8bbf..f3ac13f 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -353,6 +353,23 @@
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 @@
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