diff options
Diffstat (limited to 'drivers/crypto/exynos-rng.c')
| -rw-r--r-- | drivers/crypto/exynos-rng.c | 108 |
1 files changed, 62 insertions, 46 deletions
diff --git a/drivers/crypto/exynos-rng.c b/drivers/crypto/exynos-rng.c index 451620b475a0..86f5f459762e 100644 --- a/drivers/crypto/exynos-rng.c +++ b/drivers/crypto/exynos-rng.c @@ -1,3 +1,4 @@ +// SPDX-License-Identifier: GPL-2.0 /* * exynos-rng.c - Random Number Generator driver for the Exynos * @@ -6,15 +7,6 @@ * Loosely based on old driver from drivers/char/hw_random/exynos-rng.c: * Copyright (C) 2012 Samsung Electronics * Jonghwa Lee <jonghwa3.lee@samsung.com> - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. */ #include <linux/clk.h> @@ -22,12 +14,18 @@ #include <linux/err.h> #include <linux/io.h> #include <linux/module.h> +#include <linux/mutex.h> +#include <linux/of_device.h> #include <linux/platform_device.h> #include <crypto/internal/rng.h> #define EXYNOS_RNG_CONTROL 0x0 #define EXYNOS_RNG_STATUS 0x10 + +#define EXYNOS_RNG_SEED_CONF 0x14 +#define EXYNOS_RNG_GEN_PRNG BIT(1) + #define EXYNOS_RNG_SEED_BASE 0x140 #define EXYNOS_RNG_SEED(n) (EXYNOS_RNG_SEED_BASE + (n * 0x4)) #define EXYNOS_RNG_OUT_BASE 0x160 @@ -43,13 +41,21 @@ #define EXYNOS_RNG_SEED_REGS 5 #define EXYNOS_RNG_SEED_SIZE (EXYNOS_RNG_SEED_REGS * 4) +enum exynos_prng_type { + EXYNOS_PRNG_UNKNOWN = 0, + EXYNOS_PRNG_EXYNOS4, + EXYNOS_PRNG_EXYNOS5, +}; + /* - * Driver re-seeds itself with generated random numbers to increase - * the randomness. + * Driver re-seeds itself with generated random numbers to hinder + * backtracking of the original seed. * * Time for next re-seed in ms. */ -#define EXYNOS_RNG_RESEED_TIME 100 +#define EXYNOS_RNG_RESEED_TIME 1000 +#define EXYNOS_RNG_RESEED_BYTES 65536 + /* * In polling mode, do not wait infinitely for the engine to finish the work. */ @@ -63,13 +69,17 @@ struct exynos_rng_ctx { /* Device associated memory */ struct exynos_rng_dev { struct device *dev; + enum exynos_prng_type type; void __iomem *mem; struct clk *clk; + struct mutex lock; /* Generated numbers stored for seeding during resume */ u8 seed_save[EXYNOS_RNG_SEED_SIZE]; unsigned int seed_save_len; /* Time of last seeding in jiffies */ unsigned long last_seeding; + /* Bytes generated since last seeding */ + unsigned long bytes_seeding; }; static struct exynos_rng_dev *exynos_rng_dev; @@ -114,39 +124,12 @@ static int exynos_rng_set_seed(struct exynos_rng_dev *rng, } rng->last_seeding = jiffies; + rng->bytes_seeding = 0; return 0; } /* - * Read from output registers and put the data under 'dst' array, - * up to dlen bytes. - * - * Returns number of bytes actually stored in 'dst' (dlen - * or EXYNOS_RNG_SEED_SIZE). - */ -static unsigned int exynos_rng_copy_random(struct exynos_rng_dev *rng, - u8 *dst, unsigned int dlen) -{ - unsigned int cnt = 0; - int i, j; - u32 val; - - for (j = 0; j < EXYNOS_RNG_SEED_REGS; j++) { - val = exynos_rng_readl(rng, EXYNOS_RNG_OUT(j)); - - for (i = 0; i < 4; i++) { - dst[cnt] = val & 0xff; - val >>= 8; - if (++cnt >= dlen) - return cnt; - } - } - - return cnt; -} - -/* * Start the engine and poll for finish. Then read from output registers * filling the 'dst' buffer up to 'dlen' bytes or up to size of generated * random data (EXYNOS_RNG_SEED_SIZE). @@ -160,8 +143,13 @@ static int exynos_rng_get_random(struct exynos_rng_dev *rng, { int retry = EXYNOS_RNG_WAIT_RETRIES; - exynos_rng_writel(rng, EXYNOS_RNG_CONTROL_START, - EXYNOS_RNG_CONTROL); + if (rng->type == EXYNOS_PRNG_EXYNOS4) { + exynos_rng_writel(rng, EXYNOS_RNG_CONTROL_START, + EXYNOS_RNG_CONTROL); + } else if (rng->type == EXYNOS_PRNG_EXYNOS5) { + exynos_rng_writel(rng, EXYNOS_RNG_GEN_PRNG, + EXYNOS_RNG_SEED_CONF); + } while (!(exynos_rng_readl(rng, EXYNOS_RNG_STATUS) & EXYNOS_RNG_STATUS_RNG_DONE) && --retry) @@ -173,7 +161,9 @@ static int exynos_rng_get_random(struct exynos_rng_dev *rng, /* Clear status bit */ exynos_rng_writel(rng, EXYNOS_RNG_STATUS_RNG_DONE, EXYNOS_RNG_STATUS); - *read = exynos_rng_copy_random(rng, dst, dlen); + *read = min_t(size_t, dlen, EXYNOS_RNG_SEED_SIZE); + memcpy_fromio(dst, rng->mem + EXYNOS_RNG_OUT_BASE, *read); + rng->bytes_seeding += *read; return 0; } @@ -187,13 +177,18 @@ static void exynos_rng_reseed(struct exynos_rng_dev *rng) unsigned int read = 0; u8 seed[EXYNOS_RNG_SEED_SIZE]; - if (time_before(now, next_seeding)) + if (time_before(now, next_seeding) && + rng->bytes_seeding < EXYNOS_RNG_RESEED_BYTES) return; if (exynos_rng_get_random(rng, seed, sizeof(seed), &read)) return; exynos_rng_set_seed(rng, seed, read); + + /* Let others do some of their job. */ + mutex_unlock(&rng->lock); + mutex_lock(&rng->lock); } static int exynos_rng_generate(struct crypto_rng *tfm, @@ -209,6 +204,7 @@ static int exynos_rng_generate(struct crypto_rng *tfm, if (ret) return ret; + mutex_lock(&rng->lock); do { ret = exynos_rng_get_random(rng, dst, dlen, &read); if (ret) @@ -219,6 +215,7 @@ static int exynos_rng_generate(struct crypto_rng *tfm, exynos_rng_reseed(rng); } while (dlen > 0); + mutex_unlock(&rng->lock); clk_disable_unprepare(rng->clk); @@ -236,7 +233,9 @@ static int exynos_rng_seed(struct crypto_rng *tfm, const u8 *seed, if (ret) return ret; + mutex_lock(&rng->lock); ret = exynos_rng_set_seed(ctx->rng, seed, slen); + mutex_unlock(&rng->lock); clk_disable_unprepare(rng->clk); @@ -259,7 +258,7 @@ static struct rng_alg exynos_rng_alg = { .base = { .cra_name = "stdrng", .cra_driver_name = "exynos_rng", - .cra_priority = 100, + .cra_priority = 300, .cra_ctxsize = sizeof(struct exynos_rng_ctx), .cra_module = THIS_MODULE, .cra_init = exynos_rng_kcapi_init, @@ -279,6 +278,10 @@ static int exynos_rng_probe(struct platform_device *pdev) if (!rng) return -ENOMEM; + rng->type = (enum exynos_prng_type)of_device_get_match_data(&pdev->dev); + + mutex_init(&rng->lock); + rng->dev = &pdev->dev; rng->clk = devm_clk_get(&pdev->dev, "secss"); if (IS_ERR(rng->clk)) { @@ -329,9 +332,14 @@ static int __maybe_unused exynos_rng_suspend(struct device *dev) if (ret) return ret; + mutex_lock(&rng->lock); + /* Get new random numbers and store them for seeding on resume. */ exynos_rng_get_random(rng, rng->seed_save, sizeof(rng->seed_save), &(rng->seed_save_len)); + + mutex_unlock(&rng->lock); + dev_dbg(rng->dev, "Stored %u bytes for seeding on system resume\n", rng->seed_save_len); @@ -354,8 +362,12 @@ static int __maybe_unused exynos_rng_resume(struct device *dev) if (ret) return ret; + mutex_lock(&rng->lock); + ret = exynos_rng_set_seed(rng, rng->seed_save, rng->seed_save_len); + mutex_unlock(&rng->lock); + clk_disable_unprepare(rng->clk); return ret; @@ -367,6 +379,10 @@ static SIMPLE_DEV_PM_OPS(exynos_rng_pm_ops, exynos_rng_suspend, static const struct of_device_id exynos_rng_dt_match[] = { { .compatible = "samsung,exynos4-rng", + .data = (const void *)EXYNOS_PRNG_EXYNOS4, + }, { + .compatible = "samsung,exynos5250-prng", + .data = (const void *)EXYNOS_PRNG_EXYNOS5, }, { }, }; @@ -386,4 +402,4 @@ module_platform_driver(exynos_rng_driver); MODULE_DESCRIPTION("Exynos H/W Random Number Generator driver"); MODULE_AUTHOR("Krzysztof Kozlowski <krzk@kernel.org>"); -MODULE_LICENSE("GPL"); +MODULE_LICENSE("GPL v2"); |