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[v2] crypto: stm32/crc32 - Avoid lock if hardware is already used

Message ID 20200916063344.15054-1-nicolas.toromanoff@st.com
State Accepted
Commit bbf2cb1ea1e1428589d7f4d652bed15b265ce92d
Headers show
Series [v2] crypto: stm32/crc32 - Avoid lock if hardware is already used | expand

Commit Message

Nicolas Toromanoff Sept. 16, 2020, 6:33 a.m. UTC 
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: 7795c0baf5ac ("crypto: stm32/crc32 - protect from concurrent accesses")

Signed-off-by: Nicolas Toromanoff <nicolas.toromanoff@st.com>
---
v2: select CRC32 and not (CRYPTO_CRC32 and CRYPTO_CRC32C) in Kconfig
---
 drivers/crypto/stm32/Kconfig       |  1 +
 drivers/crypto/stm32/stm32-crc32.c | 15 ++++++++++++---
 2 files changed, 13 insertions(+), 3 deletions(-)

Comments

Herbert Xu Sept. 25, 2020, 8:15 a.m. UTC | #1 
On Wed, Sep 16, 2020 at 08:33:44AM +0200, Nicolas Toromanoff wrote:
> 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: 7795c0baf5ac ("crypto: stm32/crc32 - protect from concurrent accesses")

> 

> Signed-off-by: Nicolas Toromanoff <nicolas.toromanoff@st.com>

> ---

> v2: select CRC32 and not (CRYPTO_CRC32 and CRYPTO_CRC32C) in Kconfig

> ---

>  drivers/crypto/stm32/Kconfig       |  1 +

>  drivers/crypto/stm32/stm32-crc32.c | 15 ++++++++++++---

>  2 files changed, 13 insertions(+), 3 deletions(-)


Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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Patch

diff --git a/drivers/crypto/stm32/Kconfig b/drivers/crypto/stm32/Kconfig
index 4ef3eb11361c..4a4c3284ae1f 100644
--- a/drivers/crypto/stm32/Kconfig
+++ b/drivers/crypto/stm32/Kconfig
@@ -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.
diff --git a/drivers/crypto/stm32/stm32-crc32.c b/drivers/crypto/stm32/stm32-crc32.c
index 783a64f3f635..75867c0b0017 100644
--- a/drivers/crypto/stm32/stm32-crc32.c
+++ b/drivers/crypto/stm32/stm32-crc32.c
@@ -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);