AWS Graviton based systems provide an Arm SMC call in the vendor defined hypervisor region to read random numbers from a TRNG and return them to the guest. Co-developed-by: Ron Rindjunsky <ronrindj@xxxxxxxxxx> Signed-off-by: Ali Saidi <alisaidi@xxxxxxxxxx> Signed-off-by: Ron Rindjunsky <ronrindj@xxxxxxxxxx> --- MAINTAINERS | 6 ++ drivers/char/hw_random/Kconfig | 13 ++++ drivers/char/hw_random/Makefile | 1 + drivers/char/hw_random/graviton-rng.c | 130 ++++++++++++++++++++++++++++++++++ 4 files changed, 150 insertions(+) create mode 100644 drivers/char/hw_random/graviton-rng.c diff --git a/MAINTAINERS b/MAINTAINERS index 005902ea1450..e9c490e3fd9d 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -2771,6 +2771,12 @@ S: Maintained F: Documentation/devicetree/bindings/iio/adc/avia-hx711.txt F: drivers/iio/adc/hx711.c +AWS GRAVITON TRNG DRIVER +M: Ali Saidi <alisaidi@xxxxxxxxxx> +L: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx (moderated for non-subscribers) +S: Supported +F: drivers/char/hw_random/graviton-rng.c + AX.25 NETWORK LAYER M: Ralf Baechle <ralf@xxxxxxxxxxxxxx> L: linux-hams@xxxxxxxxxxxxxxx diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig index 25a7d8ffdb5d..7ca7386a1ac4 100644 --- a/drivers/char/hw_random/Kconfig +++ b/drivers/char/hw_random/Kconfig @@ -439,6 +439,19 @@ config HW_RANDOM_OPTEE If unsure, say Y. +config HW_RANDOM_GRAVITON + tristate "AWS Graviton Random Number Generator support" + depends on HW_RANDOM && ACPI && (ARM64 || COMPILE_TEST) + default HW_RANDOM + help + This driver provides kernel-side support for the Random Number + Generator SMC found on AWS Graviton systems. + + To compile this driver as a module, choose M here: the + module will be called graviton-rng. + + If unsure, say Y. + endif # HW_RANDOM config UML_RANDOM diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile index 7c9ef4a7667f..d1fa72670e98 100644 --- a/drivers/char/hw_random/Makefile +++ b/drivers/char/hw_random/Makefile @@ -39,3 +39,4 @@ obj-$(CONFIG_HW_RANDOM_MTK) += mtk-rng.o obj-$(CONFIG_HW_RANDOM_S390) += s390-trng.o obj-$(CONFIG_HW_RANDOM_KEYSTONE) += ks-sa-rng.o obj-$(CONFIG_HW_RANDOM_OPTEE) += optee-rng.o +obj-$(CONFIG_HW_RANDOM_GRAVITON) += graviton-rng.o diff --git a/drivers/char/hw_random/graviton-rng.c b/drivers/char/hw_random/graviton-rng.c new file mode 100644 index 000000000000..898c8bb98a20 --- /dev/null +++ b/drivers/char/hw_random/graviton-rng.c @@ -0,0 +1,130 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * AWS Graviton TRNG driver + * + * Copyright (C) 2019 Amazon Corp. + */ + +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/platform_device.h> +#include <linux/arm-smccc.h> +#include <linux/device.h> +#include <linux/hw_random.h> +#include <linux/io.h> +#include <linux/delay.h> +#include <linux/acpi.h> +#include <linux/psci.h> +#include <linux/module.h> + +#define AWS_GRAVITON_UUID \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_32, \ + ARM_SMCCC_OWNER_VENDOR_HV, 0xFF01) +#define AWS_GRAVITON_GET_VER \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_32, \ + ARM_SMCCC_OWNER_VENDOR_HV, 0xFF03) +#define AWS_GRAVITON_GET_RND \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_64, \ + ARM_SMCCC_OWNER_VENDOR_HV, 0) + +/** + * UID of the Graviton TRNG API: 1b64036c-badc-483e-99d23e283f067bdd + */ +#define GRVTN_TRNG_UUID_0 0x6c03641b +#define GRVTN_TRNG_UUID_1 0x3e48dcba +#define GRVTN_TRNG_UUID_2 0x283ed299 +#define GRVTN_TRNG_UUID_3 0xdd7b063f + +static void grvtn_smccc_conduit(u64 call_id, struct arm_smccc_res *res) +{ + if (acpi_psci_use_hvc()) + arm_smccc_1_1_hvc(call_id, res); + else + arm_smccc_1_1_smc(call_id, res); +} + +static int grvtn_trng_read(struct hwrng *trng, void *buf, size_t max, bool wait) +{ + struct arm_smccc_res res; + int err = 0; + /* timeout after one waiting period */ + int iter_remain = 2; + size_t count = max > sizeof(ulong) * 2 ? sizeof(ulong) * 2 : max; + size_t total = count; + + do { + if (err && wait) + /* Nominal wait is 5us */ + udelay(err); + + grvtn_smccc_conduit(AWS_GRAVITON_GET_RND, &res); + err = (int) res.a0; + + if (err < 0) + return err; + + iter_remain--; + } while (iter_remain && err && wait); + + if (err) + return 0; + + if (count > sizeof(ulong)) { + memcpy(buf, &res.a1, sizeof(ulong)); + count -= sizeof(ulong); + buf += sizeof(ulong); + } + memcpy(buf, &res.a2, count); + return total; +} + +static int grvtn_trng_probe(struct platform_device *pdev) +{ + int err; + struct arm_smccc_res res; + static struct hwrng ops = { + .name = "graviton", + .read = grvtn_trng_read, + .quality = 1024, /* all bits are sourced from a HW TRNG */ + }; + + grvtn_smccc_conduit(AWS_GRAVITON_UUID, &res); + + if (res.a0 != GRVTN_TRNG_UUID_0 || res.a1 != GRVTN_TRNG_UUID_1 || + res.a2 != GRVTN_TRNG_UUID_2 || res.a3 != GRVTN_TRNG_UUID_3) { + dev_err(&pdev->dev, "failed to match UUID\n"); + return -ENXIO; + } + + grvtn_smccc_conduit(AWS_GRAVITON_GET_VER, &res); + dev_info(&pdev->dev, "Graviton TRNG, SMC version %d.%d\n", + (u32)res.a0, (u32)res.a1); + + platform_set_drvdata(pdev, &ops); + err = devm_hwrng_register(&pdev->dev, &ops); + if (err) + dev_err(&pdev->dev, "failed to register hwrng"); + return err; +} + +static const struct acpi_device_id grvtn_trng_acpi_match[] = { + { "AMZN0010", }, + {} +}; + +MODULE_DEVICE_TABLE(acpi, grvtn_trng_acpi_match); + +static struct platform_driver grvtn_trng_driver = { + .probe = grvtn_trng_probe, + .driver = { + .name = "graviton-rng", + .owner = THIS_MODULE, + .acpi_match_table = ACPI_PTR(grvtn_trng_acpi_match), + }, +}; + +module_platform_driver(grvtn_trng_driver); + +MODULE_AUTHOR("Amazon.com, Inc. or it's affiliates"); +MODULE_DESCRIPTION("Graviton TRNG driver"); +MODULE_LICENSE("GPL v2"); -- 2.15.3.AMZN