Commit bbf2cb1e authored by Nicolas Toromanoff's avatar Nicolas Toromanoff Committed by Herbert Xu
Browse files

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: 7795c0ba ("crypto: stm32/crc32 - protect from concurrent accesses")

Signed-off-by: default avatarNicolas Toromanoff <nicolas.toromanoff@st.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent c4c75fcb

drivers/crypto/stm32/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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.

drivers/crypto/stm32/stm32-crc32.c

+12 −3
Original line number Diff line number Diff line
@@ -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);