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path: root/drivers/crypto/exynos-rng.c
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Diffstat (limited to 'drivers/crypto/exynos-rng.c')
-rw-r--r--drivers/crypto/exynos-rng.c108
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");
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-24 01:35:23 +0300