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crypto: stm32/crc32 - Avoid lock if hardware is already used 

If STM32 CRC device is already in use, calculate CRC by software.

This will release CPU constraint for a concurrent access to the
hardware, and avoid masking irqs during the whole block processing.

Fixes: 7795c0baf5 ("crypto: stm32/crc32 - protect from concurrent accesses")

Signed-off-by: Nicolas Toromanoff <nicolas.toromanoff@st.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Nicolas Toromanoff 2020-09-16 08:33:44 +02:00 committed by Herbert Xu
parent c4c75fcbd8
commit bbf2cb1ea1
2 changed files with 13 additions and 3 deletions
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1
drivers/crypto/stm32/Kconfig
View File

@ -3,6 +3,7 @@ config CRYPTO_DEV_STM32_CRC
tristate "Support for STM32 crc accelerators"
depends on ARCH_STM32
select CRYPTO_HASH
select CRC32
help
This enables support for the CRC32 hw accelerator which can be found
on STMicroelectronics STM32 SOC.

15
drivers/crypto/stm32/stm32-crc32.c
View File

@ -6,6 +6,7 @@
#include <linux/bitrev.h>
#include <linux/clk.h>
#include <linux/crc32.h>
#include <linux/crc32poly.h>
#include <linux/io.h>
#include <linux/kernel.h>
@ -149,7 +150,6 @@ static int burst_update(struct shash_desc *desc, const u8 *d8,
struct stm32_crc_desc_ctx *ctx = shash_desc_ctx(desc);
struct stm32_crc_ctx *mctx = crypto_shash_ctx(desc->tfm);
struct stm32_crc *crc;
unsigned long flags;
crc = stm32_crc_get_next_crc();
if (!crc)
@ -157,7 +157,15 @@ static int burst_update(struct shash_desc *desc, const u8 *d8,
pm_runtime_get_sync(crc->dev);
spin_lock_irqsave(&crc->lock, flags);
if (!spin_trylock(&crc->lock)) {
/* Hardware is busy, calculate crc32 by software */
if (mctx->poly == CRC32_POLY_LE)
ctx->partial = crc32_le(ctx->partial, d8, length);
else
ctx->partial = __crc32c_le(ctx->partial, d8, length);
goto pm_out;
}
/*
* Restore previously calculated CRC for this context as init value
@ -197,8 +205,9 @@ static int burst_update(struct shash_desc *desc, const u8 *d8,
/* Store partial result */
ctx->partial = readl_relaxed(crc->regs + CRC_DR);
spin_unlock_irqrestore(&crc->lock, flags);
spin_unlock(&crc->lock);
pm_out:
pm_runtime_mark_last_busy(crc->dev);
pm_runtime_put_autosuspend(crc->dev);