/* SPDX-License-Identifier: GPL-2.0 OR MIT */
/*
 * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
 */

#include <asm/hwcap.h>
#include <asm/neon.h>
#if defined(CONFIG_ARM)
#include <asm/system_info.h>
#include <asm/cputype.h>
#endif

#define ARM_USE_NEON (defined(CONFIG_KERNEL_MODE_NEON) &&                      \
		      (defined(CONFIG_ARM64) ||                                \
		       (defined(__LINUX_ARM_ARCH__) &&                         \
			__LINUX_ARM_ARCH__ == 7)))

asmlinkage void chacha20_arm(u8 *out, const u8 *in, const size_t len,
			     const u32 key[8], const u32 counter[4]);
#if defined(CONFIG_ARM)
asmlinkage void hchacha20_arm(const u32 state[16], u32 out[8]);
#endif
#if ARM_USE_NEON
asmlinkage void chacha20_neon(u8 *out, const u8 *in, const size_t len,
			      const u32 key[8], const u32 counter[4]);
#endif

static bool chacha20_use_neon __ro_after_init;

static void __init chacha20_fpu_init(void)
{
#if defined(CONFIG_ARM64)
	chacha20_use_neon = elf_hwcap & HWCAP_ASIMD;
#elif defined(CONFIG_ARM)
	switch (read_cpuid_part()) {
	case ARM_CPU_PART_CORTEX_A7:
	case ARM_CPU_PART_CORTEX_A5:
		/* The Cortex-A7 and Cortex-A5 do not perform well with the NEON
		 * implementation but do incredibly with the scalar one and use
		 * less power.
		 */
		break;
	default:
		chacha20_use_neon = elf_hwcap & HWCAP_NEON;
	}
#endif
}

static inline bool chacha20_arch(struct chacha20_ctx *state, u8 *dst,
				 const u8 *src, size_t len,
				 simd_context_t *simd_context)
{
#if ARM_USE_NEON
	if (chacha20_use_neon && len >= CHACHA20_BLOCK_SIZE * 3 &&
	    simd_use(simd_context))
		chacha20_neon(dst, src, len, state->key, state->counter);
	else
#endif
		chacha20_arm(dst, src, len, state->key, state->counter);

	state->counter[0] += (len + 63) / 64;
	return true;
}

static inline bool hchacha20_arch(u8 *derived_key, const u8 *nonce,
				  const u8 *key, simd_context_t *simd_context)
{
#if defined(CONFIG_ARM)
	u32 x[] = { CHACHA20_CONSTANT_EXPA,
		    CHACHA20_CONSTANT_ND_3,
		    CHACHA20_CONSTANT_2_BY,
		    CHACHA20_CONSTANT_TE_K,
		    get_unaligned_le32(key + 0),
		    get_unaligned_le32(key + 4),
		    get_unaligned_le32(key + 8),
		    get_unaligned_le32(key + 12),
		    get_unaligned_le32(key + 16),
		    get_unaligned_le32(key + 20),
		    get_unaligned_le32(key + 24),
		    get_unaligned_le32(key + 28),
		    get_unaligned_le32(nonce + 0),
		    get_unaligned_le32(nonce + 4),
		    get_unaligned_le32(nonce + 8),
		    get_unaligned_le32(nonce + 12)
	};
	hchacha20_arm(x, (u32 *)derived_key);
	return true;
#else
	return false;
#endif
}