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At the moment we probe for the Random Number Generator SMCCC service, and use that in the core code (arch_get_random). However the hardware entropy can also be useful to access from userland, and be it to assess its quality. Register a platform device when the SMCCC TRNG service is detected, to allow a hw_random driver to hook onto this. The function registering the device is deliberately made in a way which allows expansion, so other services that could be exposed via a platform device (or some other interface), can be added here easily. Signed-off-by: Andre Przywara <andre.przywara@arm.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Mark Brown <broonie@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
62 lines
1.4 KiB
C
62 lines
1.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2020 Arm Limited
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*/
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#define pr_fmt(fmt) "smccc: " fmt
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#include <linux/cache.h>
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#include <linux/init.h>
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#include <linux/arm-smccc.h>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <asm/archrandom.h>
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static u32 smccc_version = ARM_SMCCC_VERSION_1_0;
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static enum arm_smccc_conduit smccc_conduit = SMCCC_CONDUIT_NONE;
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bool __ro_after_init smccc_trng_available = false;
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u64 __ro_after_init smccc_has_sve_hint = false;
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void __init arm_smccc_version_init(u32 version, enum arm_smccc_conduit conduit)
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{
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smccc_version = version;
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smccc_conduit = conduit;
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smccc_trng_available = smccc_probe_trng();
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if (IS_ENABLED(CONFIG_ARM64_SVE) &&
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smccc_version >= ARM_SMCCC_VERSION_1_3)
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smccc_has_sve_hint = true;
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}
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enum arm_smccc_conduit arm_smccc_1_1_get_conduit(void)
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{
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if (smccc_version < ARM_SMCCC_VERSION_1_1)
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return SMCCC_CONDUIT_NONE;
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return smccc_conduit;
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}
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EXPORT_SYMBOL_GPL(arm_smccc_1_1_get_conduit);
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u32 arm_smccc_get_version(void)
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{
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return smccc_version;
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}
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EXPORT_SYMBOL_GPL(arm_smccc_get_version);
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static int __init smccc_devices_init(void)
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{
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struct platform_device *pdev;
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if (smccc_trng_available) {
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pdev = platform_device_register_simple("smccc_trng", -1,
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NULL, 0);
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if (IS_ERR(pdev))
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pr_err("smccc_trng: could not register device: %ld\n",
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PTR_ERR(pdev));
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}
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return 0;
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}
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device_initcall(smccc_devices_init);
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