/*
 * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#ifndef __ASM_CPUFEATURE_H
#define __ASM_CPUFEATURE_H

#include <asm/hwcap.h>
#include <asm/sysreg.h>

/*
 * In the arm64 world (as in the ARM world), elf_hwcap is used both internally
 * in the kernel and for user space to keep track of which optional features
 * are supported by the current system. So let's map feature 'x' to HWCAP_x.
 * Note that HWCAP_x constants are bit fields so we need to take the log.
 */

#define MAX_CPU_FEATURES        (8 * sizeof(elf_hwcap))
#define cpu_feature(x)          ilog2(HWCAP_ ## x)

#define ARM64_WORKAROUND_CLEAN_CACHE            0
#define ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE    1
#define ARM64_WORKAROUND_845719                 2
#define ARM64_HAS_SYSREG_GIC_CPUIF              3
#define ARM64_HAS_PAN                           4
#define ARM64_HAS_LSE_ATOMICS                   5
#define ARM64_WORKAROUND_CAVIUM_23154           6
#define ARM64_WORKAROUND_834220                 7

#define ARM64_NCAPS                             8

#ifndef __ASSEMBLY__

#include <linux/kernel.h>

/* CPU feature register tracking */
enum ftr_type {
        FTR_EXACT,      /* Use a predefined safe value */
        FTR_LOWER_SAFE, /* Smaller value is safe */
        FTR_HIGHER_SAFE,/* Bigger value is safe */
};

#define FTR_STRICT      true    /* SANITY check strict matching required */
#define FTR_NONSTRICT   false   /* SANITY check ignored */

#define FTR_SIGNED      true    /* Value should be treated as signed */
#define FTR_UNSIGNED    false   /* Value should be treated as unsigned */

struct arm64_ftr_bits {
        bool            sign;   /* Value is signed ? */
        bool            strict; /* CPU Sanity check: strict matching required ? */
        enum ftr_type   type;
        u8              shift;
        u8              width;
        s64             safe_val; /* safe value for discrete features */
};

/*
 * @arm64_ftr_reg - Feature register
 * @strict_mask         Bits which should match across all CPUs for sanity.
 * @sys_val             Safe value across the CPUs (system view)
 */
struct arm64_ftr_reg {
        u32                     sys_id;
        const char              *name;
        u64                     strict_mask;
        u64                     sys_val;
        struct arm64_ftr_bits   *ftr_bits;
};

struct arm64_cpu_capabilities {
        const char *desc;
        u16 capability;
        bool (*matches)(const struct arm64_cpu_capabilities *);
        void (*enable)(void *);         /* Called on all active CPUs */
        union {
                struct {        /* To be used for erratum handling only */
                        u32 midr_model;
                        u32 midr_range_min, midr_range_max;
                };

                struct {        /* Feature register checking */
                        u32 sys_reg;
                        int field_pos;
                        int min_field_value;
                        int hwcap_type;
                        unsigned long hwcap;
                };
        };
};

extern DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS);

static inline bool cpu_have_feature(unsigned int num)
{
        return elf_hwcap & (1UL << num);
}

static inline bool cpus_have_cap(unsigned int num)
{
        if (num >= ARM64_NCAPS)
                return false;
        return test_bit(num, cpu_hwcaps);
}

static inline void cpus_set_cap(unsigned int num)
{
        if (num >= ARM64_NCAPS)
                pr_warn("Attempt to set an illegal CPU capability (%d >= %d)\n",
                        num, ARM64_NCAPS);
        else
                __set_bit(num, cpu_hwcaps);
}

static inline int __attribute_const__
cpuid_feature_extract_field_width(u64 features, int field, int width)
{
        return (s64)(features << (64 - width - field)) >> (64 - width);
}

static inline int __attribute_const__
cpuid_feature_extract_field(u64 features, int field)
{
        return cpuid_feature_extract_field_width(features, field, 4);
}

static inline unsigned int __attribute_const__
cpuid_feature_extract_unsigned_field_width(u64 features, int field, int width)
{
        return (u64)(features << (64 - width - field)) >> (64 - width);
}

static inline unsigned int __attribute_const__
cpuid_feature_extract_unsigned_field(u64 features, int field)
{
        return cpuid_feature_extract_unsigned_field_width(features, field, 4);
}

static inline u64 arm64_ftr_mask(struct arm64_ftr_bits *ftrp)
{
        return (u64)GENMASK(ftrp->shift + ftrp->width - 1, ftrp->shift);
}

static inline s64 arm64_ftr_value(struct arm64_ftr_bits *ftrp, u64 val)
{
        return ftrp->sign ?
                cpuid_feature_extract_field_width(val, ftrp->shift, ftrp->width) :
                cpuid_feature_extract_unsigned_field_width(val, ftrp->shift, ftrp->width);
}

static inline bool id_aa64mmfr0_mixed_endian_el0(u64 mmfr0)
{
        return cpuid_feature_extract_field(mmfr0, ID_AA64MMFR0_BIGENDEL_SHIFT) == 0x1 ||
                cpuid_feature_extract_field(mmfr0, ID_AA64MMFR0_BIGENDEL0_SHIFT) == 0x1;
}

void __init setup_cpu_features(void);

void update_cpu_capabilities(const struct arm64_cpu_capabilities *caps,
                            const char *info);
void check_local_cpu_errata(void);

#ifdef CONFIG_HOTPLUG_CPU
void verify_local_cpu_capabilities(void);
#else
static inline void verify_local_cpu_capabilities(void)
{
}
#endif

u64 read_system_reg(u32 id);

static inline bool cpu_supports_mixed_endian_el0(void)
{
        return id_aa64mmfr0_mixed_endian_el0(read_cpuid(ID_AA64MMFR0_EL1));
}

static inline bool system_supports_mixed_endian_el0(void)
{
        return id_aa64mmfr0_mixed_endian_el0(read_system_reg(SYS_ID_AA64MMFR0_EL1));
}

#endif /* __ASSEMBLY__ */

#endif