96 lines
2.3 KiB
C
96 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* RNG driver for Zhaoxin RNGs
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*
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* Copyright 2023 (c) Zhaoxin Semiconductor Co., Ltd
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*/
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#include <crypto/padlock.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/hw_random.h>
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#include <linux/delay.h>
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#include <linux/io.h>
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#include <linux/cpufeature.h>
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#include <asm/cpu_device_id.h>
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#include <asm/fpu/api.h>
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enum {
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ZHAOXIN_RNG_CHUNK_8 = 0x00, /* 64 rand bits, 64 stored bits */
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ZHAOXIN_RNG_CHUNK_4 = 0x01, /* 32 rand bits, 32 stored bits */
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ZHAOXIN_RNG_CHUNK_2 = 0x02, /* 16 rand bits, 32 stored bits */
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ZHAOXIN_RNG_CHUNK_1 = 0x03, /* 8 rand bits, 32 stored bits */
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ZHAOXIN_RNG_MAX_SIZE = (128 * 1024),
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};
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static int zhaoxin_rng_init(struct hwrng *rng)
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{
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if (!boot_cpu_has(X86_FEATURE_XSTORE_EN)) {
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pr_err(PFX "can't enable hardware RNG if XSTORE is not enabled\n");
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return -ENODEV;
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}
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return 0;
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}
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static inline int rep_xstore(size_t size, size_t factor, void *result)
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{
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asm(".byte 0xf3, 0x0f, 0xa7, 0xc0"
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: "=m"(*(size_t *)result), "+c"(size), "+d"(factor), "+D"(result));
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return 0;
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}
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static int zhaoxin_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
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{
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if (max > ZHAOXIN_RNG_MAX_SIZE)
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max = ZHAOXIN_RNG_MAX_SIZE;
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rep_xstore(max, ZHAOXIN_RNG_CHUNK_1, data);
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return max;
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}
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static struct hwrng zhaoxin_rng = {
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.name = "zhaoxin",
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.init = zhaoxin_rng_init,
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.read = zhaoxin_rng_read,
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};
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static const struct x86_cpu_id zhaoxin_rng_cpu_ids[] = {
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X86_MATCH_VENDOR_FAM_FEATURE(ZHAOXIN, 6, X86_FEATURE_XSTORE, NULL),
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X86_MATCH_VENDOR_FAM_FEATURE(ZHAOXIN, 7, X86_FEATURE_XSTORE, NULL),
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X86_MATCH_VENDOR_FAM_FEATURE(CENTAUR, 7, X86_FEATURE_XSTORE, NULL),
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{}
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};
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MODULE_DEVICE_TABLE(x86cpu, zhaoxin_rng_cpu_ids);
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static int __init zhaoxin_rng_mod_init(void)
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{
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int err;
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if (!x86_match_cpu(zhaoxin_rng_cpu_ids)) {
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pr_err(PFX "The CPU isn't support XSTORE.\n");
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return -ENODEV;
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}
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pr_info("Zhaoxin RNG detected\n");
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err = hwrng_register(&zhaoxin_rng);
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if (err)
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pr_err(PFX "RNG registering failed (%d)\n", err);
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return err;
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}
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module_init(zhaoxin_rng_mod_init);
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static void __exit zhaoxin_rng_mod_exit(void)
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{
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hwrng_unregister(&zhaoxin_rng);
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}
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module_exit(zhaoxin_rng_mod_exit);
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MODULE_DESCRIPTION("H/W RNG driver for Zhaoxin CPUs");
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MODULE_AUTHOR("YunShen@zhaoxin.com");
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MODULE_LICENSE("GPL");
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