Re: [PATCH v3 2/4] crypto: exynos - Improve performance of PRNG
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From: Krzysztof Kozlowski <krzk@kernel.org>
Date: 2017-12-13 08:08:03
Also in:
linux-samsung-soc, lkml
On Tue, Dec 12, 2017 at 5:36 PM, Łukasz Stelmach [off-list ref] wrote:
Use memcpy_fromio() instead of custom exynos_rng_copy_random() function to retrieve generated numbers from the registers of PRNG.
If I recall correctly, you mentioned before that it improves the
performance. If so it would be nice to mention some numbers here.
Anyway it is fine with me:
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Best regards,
Krzysztof
quoted hunk ↗ jump to hunk
Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com> --- drivers/crypto/exynos-rng.c | 31 ++----------------------------- 1 file changed, 2 insertions(+), 29 deletions(-)diff --git a/drivers/crypto/exynos-rng.c b/drivers/crypto/exynos-rng.c index 825c09619eb8..dcdd444d0b3b 100644 --- a/drivers/crypto/exynos-rng.c +++ b/drivers/crypto/exynos-rng.c@@ -131,34 +131,6 @@ static int exynos_rng_set_seed(struct exynos_rng_dev *rng, } /* - * 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).@@ -190,7 +162,8 @@ 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); return 0; } --2.11.0