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From:   Nicolas Toromanoff <nicolas.toromanoff@foss.st.com>
To:     Herbert Xu <herbert@gondor.apana.org.au>,
        "David S . Miller" <davem@davemloft.net>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>
CC:     Marek Vasut <marex@denx.de>,
        Nicolas Toromanoff <nicolas.toromanoff@foss.st.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        <linux-crypto@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
Subject: [PATCH v2 8/8] crypto: stm32/cryp - reorder hw initialization
Date:   Tue, 2 Nov 2021 17:47:29 +0100
Message-ID: <20211102164729.9957-9-nicolas.toromanoff@foss.st.com>
In-Reply-To: <20211102164729.9957-1-nicolas.toromanoff@foss.st.com>
References: <20211102164729.9957-1-nicolas.toromanoff@foss.st.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

The CRYP IP checks the written key depending of the configuration, it's
safer to write the whole configuration to hardware then the key to avoid
unexpected key rejection.

Signed-off-by: Nicolas Toromanoff <nicolas.toromanoff@foss.st.com>
---
 drivers/crypto/stm32/stm32-cryp.c | 39 ++++++++++++++++++++-----------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/drivers/crypto/stm32/stm32-cryp.c b/drivers/crypto/stm32/stm32-cryp.c
index 5962fbb0bc91..d99eea9cb8cd 100644
--- a/drivers/crypto/stm32/stm32-cryp.c
+++ b/drivers/crypto/stm32/stm32-cryp.c
@@ -232,6 +232,11 @@ static inline int stm32_cryp_wait_busy(struct stm32_cryp *cryp)
 			!(status & SR_BUSY), 10, 100000);
 }
 
+static inline void stm32_cryp_enable(struct stm32_cryp *cryp)
+{
+	writel_relaxed(readl_relaxed(cryp->regs + CRYP_CR) | CR_CRYPEN, cryp->regs + CRYP_CR);
+}
+
 static inline int stm32_cryp_wait_enable(struct stm32_cryp *cryp)
 {
 	u32 status;
@@ -534,9 +539,6 @@ static int stm32_cryp_hw_init(struct stm32_cryp *cryp)
 	/* Disable interrupt */
 	stm32_cryp_write(cryp, CRYP_IMSCR, 0);
 
-	/* Set key */
-	stm32_cryp_hw_write_key(cryp);
-
 	/* Set configuration */
 	cfg = CR_DATA8 | CR_FFLUSH;
 
@@ -562,23 +564,36 @@ static int stm32_cryp_hw_init(struct stm32_cryp *cryp)
 	/* AES ECB/CBC decrypt: run key preparation first */
 	if (is_decrypt(cryp) &&
 	    ((hw_mode == CR_AES_ECB) || (hw_mode == CR_AES_CBC))) {
-		stm32_cryp_write(cryp, CRYP_CR, cfg | CR_AES_KP | CR_CRYPEN);
+		/* Configure in key preparation mode */
+		stm32_cryp_write(cryp, CRYP_CR, cfg | CR_AES_KP);
 
+		/* Set key only after full configuration done */
+		stm32_cryp_hw_write_key(cryp);
+
+		/* Start prepare key */
+		stm32_cryp_enable(cryp);
 		/* Wait for end of processing */
 		ret = stm32_cryp_wait_busy(cryp);
 		if (ret) {
 			dev_err(cryp->dev, "Timeout (key preparation)\n");
 			return ret;
 		}
-	}
 
-	cfg |= hw_mode;
+		cfg |= hw_mode | CR_DEC_NOT_ENC;
 
-	if (is_decrypt(cryp))
-		cfg |= CR_DEC_NOT_ENC;
+		/* Apply updated config (Decrypt + algo) and flush */
+		stm32_cryp_write(cryp, CRYP_CR, cfg);
+	} else {
+		cfg |= hw_mode;
+		if (is_decrypt(cryp))
+			cfg |= CR_DEC_NOT_ENC;
 
-	/* Apply config and flush (valid when CRYPEN = 0) */
-	stm32_cryp_write(cryp, CRYP_CR, cfg);
+		/* Apply config and flush */
+		stm32_cryp_write(cryp, CRYP_CR, cfg);
+
+		/* Set key only after configuration done */
+		stm32_cryp_hw_write_key(cryp);
+	}
 
 	switch (hw_mode) {
 	case CR_AES_GCM:
@@ -606,9 +621,7 @@ static int stm32_cryp_hw_init(struct stm32_cryp *cryp)
 	}
 
 	/* Enable now */
-	cfg |= CR_CRYPEN;
-
-	stm32_cryp_write(cryp, CRYP_CR, cfg);
+	stm32_cryp_enable(cryp);
 
 	return 0;
 }
-- 
2.17.1