crypto: s5p-sss: Add aes-ctr support

Add support for aes counter(ctr) block cipher mode of operation for
Exynos Hardware. In contrast to ecb and cbc modes, aes-ctr allows
encyption/decryption for request sizes not being a multiple of 16(bytes).

Hardware requires block sizes being a multiple of 16(bytes). In order to
achieve this, copy request source and destination memory, and align it's size
to 16. That way hardware processes additional bytes, that are omitted
when copying the result back to its original destination.

Tested on Odroid-U3 with Exynos 4412 CPU, kernel 4.19-rc2 with crypto
run-time self test testmgr.

Signed-off-by: Christoph Manszewski <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Acked-by: Kamil Konieczny <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/s5p-sss.c

···
 };
 
 static void s5p_set_aes(struct s5p_aes_dev *dev,
-			const u8 *key, const u8 *iv,
+			const u8 *key, const u8 *iv, const u8 *ctr,
 			unsigned int keylen)
 {
 	void __iomem *keystart;
 
 	if (iv)
 		memcpy_toio(dev->aes_ioaddr + SSS_REG_AES_IV_DATA(0), iv, 0x10);
+
+	if (ctr)
+		memcpy_toio(dev->aes_ioaddr + SSS_REG_AES_CNT_DATA(0), ctr, 0x10);
 
 	if (keylen == AES_KEYSIZE_256)
 		keystart = dev->aes_ioaddr + SSS_REG_AES_KEY_DATA(0);
···
 	u32 aes_control;
 	unsigned long flags;
 	int err;
-	u8 *iv;
+	u8 *iv, *ctr;
 
+	/* This sets bit [13:12] to 00, which selects 128-bit counter */
 	aes_control = SSS_AES_KEY_CHANGE_MODE;
 	if (mode & FLAGS_AES_DECRYPT)
 		aes_control |= SSS_AES_MODE_DECRYPT;
···
 	if ((mode & FLAGS_AES_MODE_MASK) == FLAGS_AES_CBC) {
 		aes_control |= SSS_AES_CHAIN_MODE_CBC;
 		iv = req->info;
+		ctr = NULL;
 	} else if ((mode & FLAGS_AES_MODE_MASK) == FLAGS_AES_CTR) {
 		aes_control |= SSS_AES_CHAIN_MODE_CTR;
-		iv = req->info;
+		iv = NULL;
+		ctr = req->info;
 	} else {
 		iv = NULL; /* AES_ECB */
+		ctr = NULL;
 	}
 
 	if (dev->ctx->keylen == AES_KEYSIZE_192)
···
 		goto outdata_error;
 
 	SSS_AES_WRITE(dev, AES_CONTROL, aes_control);
-	s5p_set_aes(dev, dev->ctx->aes_key, iv, dev->ctx->keylen);
+	s5p_set_aes(dev, dev->ctx->aes_key, iv, ctr, dev->ctx->keylen);
 
 	s5p_set_dma_indata(dev,  dev->sg_src);
 	s5p_set_dma_outdata(dev, dev->sg_dst);
···
 	struct s5p_aes_ctx *ctx = crypto_ablkcipher_ctx(tfm);
 	struct s5p_aes_dev *dev = ctx->dev;
 
-	if (!IS_ALIGNED(req->nbytes, AES_BLOCK_SIZE)) {
+	if (!IS_ALIGNED(req->nbytes, AES_BLOCK_SIZE) &&
+			((mode & FLAGS_AES_MODE_MASK) != FLAGS_AES_CTR)) {
 		dev_err(dev->dev, "request size is not exact amount of AES blocks\n");
 		return -EINVAL;
 	}
···
 static int s5p_aes_cbc_decrypt(struct ablkcipher_request *req)
 {
 	return s5p_aes_crypt(req, FLAGS_AES_DECRYPT | FLAGS_AES_CBC);
+}
+
+static int s5p_aes_ctr_crypt(struct ablkcipher_request *req)
+{
+	return s5p_aes_crypt(req, FLAGS_AES_CTR);
 }
 
 static int s5p_aes_cra_init(struct crypto_tfm *tfm)
···
 			.setkey		= s5p_aes_setkey,
 			.encrypt	= s5p_aes_cbc_encrypt,
 			.decrypt	= s5p_aes_cbc_decrypt,
+		}
+	},
+	{
+		.cra_name		= "ctr(aes)",
+		.cra_driver_name	= "ctr-aes-s5p",
+		.cra_priority		= 100,
+		.cra_flags		= CRYPTO_ALG_TYPE_ABLKCIPHER |
+					  CRYPTO_ALG_ASYNC |
+					  CRYPTO_ALG_KERN_DRIVER_ONLY,
+		.cra_blocksize		= AES_BLOCK_SIZE,
+		.cra_ctxsize		= sizeof(struct s5p_aes_ctx),
+		.cra_alignmask		= 0x0f,
+		.cra_type		= &crypto_ablkcipher_type,
+		.cra_module		= THIS_MODULE,
+		.cra_init		= s5p_aes_cra_init,
+		.cra_u.ablkcipher = {
+			.min_keysize	= AES_MIN_KEY_SIZE,
+			.max_keysize	= AES_MAX_KEY_SIZE,
+			.ivsize		= AES_BLOCK_SIZE,
+			.setkey		= s5p_aes_setkey,
+			.encrypt	= s5p_aes_ctr_crypt,
+			.decrypt	= s5p_aes_ctr_crypt,
 		}
 	},
 };