linux/arch/powerpc/include/asm/cpu_has_feature.h
Nicholas Piggin 5a61ef74f2 powerpc/64s: Support new device tree binding for discovering CPU features
The ibm,powerpc-cpu-features device tree binding describes CPU features with
ASCII names and extensible compatibility, privilege, and enablement metadata
that allows improved flexibility and compatibility with new hardware.

The interface is described in detail in ibm,powerpc-cpu-features.txt in this
patch.

Currently this code is not enabled by default, and there are no released
firmwares that provide the binding.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2017-05-09 23:42:55 +10:00

56 lines
1.3 KiB
C

#ifndef __ASM_POWERPC_CPU_HAS_FEATURE_H
#define __ASM_POWERPC_CPU_HAS_FEATURE_H
#ifndef __ASSEMBLY__
#include <linux/bug.h>
#include <asm/cputable.h>
static inline bool early_cpu_has_feature(unsigned long feature)
{
return !!((CPU_FTRS_ALWAYS & feature) ||
(CPU_FTRS_POSSIBLE & cur_cpu_spec->cpu_features & feature));
}
#ifdef CONFIG_JUMP_LABEL_FEATURE_CHECKS
#include <linux/jump_label.h>
#define NUM_CPU_FTR_KEYS BITS_PER_LONG
extern struct static_key_true cpu_feature_keys[NUM_CPU_FTR_KEYS];
static __always_inline bool cpu_has_feature(unsigned long feature)
{
int i;
#ifndef __clang__ /* clang can't cope with this */
BUILD_BUG_ON(!__builtin_constant_p(feature));
#endif
#ifdef CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG
if (!static_key_initialized) {
printk("Warning! cpu_has_feature() used prior to jump label init!\n");
dump_stack();
return early_cpu_has_feature(feature);
}
#endif
if (CPU_FTRS_ALWAYS & feature)
return true;
if (!(CPU_FTRS_POSSIBLE & feature))
return false;
i = __builtin_ctzl(feature);
return static_branch_likely(&cpu_feature_keys[i]);
}
#else
static inline bool cpu_has_feature(unsigned long feature)
{
return early_cpu_has_feature(feature);
}
#endif
#endif /* __ASSEMBLY__ */
#endif /* __ASM_POWERPC_CPU_HAS_FEATURE_H */