[PATCH v2] ASoC: cros_ec_codec: switch to library API for SHA-256

[Ard Biesheuvel <ardb@kernel.org>]

The CrOS EC codec driver uses SHA-256 explicitly, and not in a
performance critical manner, so there is really no point in using
the SHASH crypto API here. Let's switch to the library API instead.

Cc: Cheng-Yi Chiang <cychiang@chromium.org>
Cc: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Benson Leung <bleung@chromium.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Tzung-Bi Shih <tzungbi@google.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
v2:
- rebase onto sound/for-5.8
- drop pointless memzero_explicit()
- drop include of crypto/hash.h

 sound/soc/codecs/Kconfig         |  3 +--
 sound/soc/codecs/cros_ec_codec.c | 23 ++++----------------
 2 files changed, 5 insertions(+), 21 deletions(-)

diff --git a/sound/soc/codecs/Kconfig b/sound/soc/codecs/Kconfig
index 44b8c4cde4f3..2d4f1b4bc011 100644
--- a/sound/soc/codecs/Kconfig
+++ b/sound/soc/codecs/Kconfig
@@ -538,8 +538,7 @@ config SND_SOC_CQ0093VC
 config SND_SOC_CROS_EC_CODEC
 	tristate "codec driver for ChromeOS EC"
 	depends on CROS_EC
-	select CRYPTO
-	select CRYPTO_SHA256
+	select CRYPTO_LIB_SHA256
 	help
 	  If you say yes here you will get support for the
 	  ChromeOS Embedded Controller's Audio Codec.
diff --git a/sound/soc/codecs/cros_ec_codec.c b/sound/soc/codecs/cros_ec_codec.c
index 1948bc6971f6..8d45c628e988 100644
--- a/sound/soc/codecs/cros_ec_codec.c
+++ b/sound/soc/codecs/cros_ec_codec.c
@@ -8,7 +8,6 @@
  * EC for audio function.
  */
 
-#include <crypto/hash.h>
 #include <crypto/sha.h>
 #include <linux/acpi.h>
 #include <linux/delay.h>
@@ -107,25 +106,11 @@ static int send_ec_host_command(struct cros_ec_device *ec_dev, uint32_t cmd,
 static int calculate_sha256(struct cros_ec_codec_priv *priv,
 			    uint8_t *buf, uint32_t size, uint8_t *digest)
 {
-	struct crypto_shash *tfm;
-	struct shash_desc *desc;
+	struct sha256_state sctx;
 
-	tfm = crypto_alloc_shash("sha256", CRYPTO_ALG_TYPE_SHASH, 0);
-	if (IS_ERR(tfm)) {
-		dev_err(priv->dev, "can't alloc shash\n");
-		return PTR_ERR(tfm);
-	}
-	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(tfm), GFP_KERNEL);
-	if (!desc) {
-		crypto_free_shash(tfm);
-		return -ENOMEM;
-	}
-	desc->tfm = tfm;
-	crypto_shash_digest(desc, buf, size, digest);
-	shash_desc_zero(desc);
-
-	kfree(desc);
-	crypto_free_shash(tfm);
+	sha256_init(&sctx);
+	sha256_update(&sctx, buf, size);
+	sha256_final(&sctx, digest);
 
 #ifdef DEBUG
 	{
-- 
2.17.1