| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| 459 | 97.87% | 1 | 33.33% | |
| 5 | 1.07% | 1 | 33.33% | |
| 5 | 1.07% | 1 | 33.33% | |
| Total | 469 | 3 |
| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Andre Przywara | 459 | 97.87% | 1 | 33.33% |
| Jeff Johnson | 5 | 1.07% | 1 | 33.33% |
| James Cowgill | 5 | 1.07% | 1 | 33.33% |
| Total | 469 | 3 |
// SPDX-License-Identifier: GPL-2.0 /* * Randomness driver for the ARM SMCCC TRNG Firmware Interface * https://developer.arm.com/documentation/den0098/latest/ * * Copyright (C) 2020 Arm Ltd. * * The ARM TRNG firmware interface specifies a protocol to read entropy * from a higher exception level, to abstract from any machine specific * implemenations and allow easier use in hypervisors. * * The firmware interface is realised using the SMCCC specification. */ #include <linux/bits.h> #include <linux/device.h> #include <linux/hw_random.h> #include <linux/module.h> #include <linux/platform_device.h> #include <linux/arm-smccc.h> #ifdef CONFIG_ARM64 #define ARM_SMCCC_TRNG_RND ARM_SMCCC_TRNG_RND64 #define MAX_BITS_PER_CALL (3 * 64UL) #else #define ARM_SMCCC_TRNG_RND ARM_SMCCC_TRNG_RND32 #define MAX_BITS_PER_CALL (3 * 32UL) #endif /* We don't want to allow the firmware to stall us forever. */ #define SMCCC_TRNG_MAX_TRIES 20 #define SMCCC_RET_TRNG_INVALID_PARAMETER -2 #define SMCCC_RET_TRNG_NO_ENTROPY -3 static int copy_from_registers(char *buf, struct arm_smccc_res *res, size_t bytes) { unsigned int chunk, copied; if (bytes == 0) return 0; chunk = min(bytes, sizeof(long)); memcpy(buf, &res->a3, chunk); copied = chunk; if (copied >= bytes) return copied; chunk = min((bytes - copied), sizeof(long)); memcpy(&buf[copied], &res->a2, chunk); copied += chunk; if (copied >= bytes) return copied; chunk = min((bytes - copied), sizeof(long)); memcpy(&buf[copied], &res->a1, chunk); return copied + chunk; } static int smccc_trng_read(struct hwrng *rng, void *data, size_t max, bool wait) { struct arm_smccc_res res; u8 *buf = data; unsigned int copied = 0; int tries = 0; while (copied < max) { size_t bits = min_t(size_t, (max - copied) * BITS_PER_BYTE, MAX_BITS_PER_CALL); arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND, bits, &res); switch ((int)res.a0) { case SMCCC_RET_SUCCESS: copied += copy_from_registers(buf + copied, &res, bits / BITS_PER_BYTE); tries = 0; break; case SMCCC_RET_TRNG_NO_ENTROPY: if (!wait) return copied; tries++; if (tries >= SMCCC_TRNG_MAX_TRIES) return copied; cond_resched(); break; default: return -EIO; } } return copied; } static int smccc_trng_probe(struct platform_device *pdev) { struct hwrng *trng; trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL); if (!trng) return -ENOMEM; trng->name = "smccc_trng"; trng->read = smccc_trng_read; return devm_hwrng_register(&pdev->dev, trng); } static struct platform_driver smccc_trng_driver = { .driver = { .name = "smccc_trng", }, .probe = smccc_trng_probe, }; module_platform_driver(smccc_trng_driver); MODULE_ALIAS("platform:smccc_trng"); MODULE_AUTHOR("Andre Przywara"); MODULE_DESCRIPTION("Arm SMCCC TRNG firmware interface support"); MODULE_LICENSE("GPL");