crypto: aes: Add software AES DM driver

This adds AES crypto engine using the AES Uclass implemented in software,
serves as example implementation and for uclass tests.

Those implementing HW AES crypto engine drivers can use this as basis and
replace software parts with the HW specifics of their device.

Signed-off-by: Ion Agorria <ion@agorria.com>

drivers/crypto/aes/Kconfig

@@ -3,3 +3,10 @@ config DM_AES
 	depends on DM
 	help
 	  If you want to use driver model for AES crypto operations, say Y.
+
+config AES_SOFTWARE
+	bool "Enable driver for AES in software"
+	depends on DM_AES && AES
+	help
+	  Enable driver for AES crypto operations in software. Uses U-Boot
+	  AES library.

drivers/crypto/aes/Makefile

@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0+
 
 obj-$(CONFIG_$(PHASE_)DM_AES) += aes-uclass.o
+obj-$(CONFIG_$(PHASE_)AES_SOFTWARE) += aes-sw.o

drivers/crypto/aes/aes-sw.c

@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <config.h>
+#include <dm.h>
+#include <log.h>
+#include <malloc.h>
+#include <uboot_aes.h>
+
+#define SW_KEY_SLOTS 2
+
+struct sw_aes_priv {
+	u8 key_slots[SW_KEY_SLOTS][AES256_KEY_LENGTH];
+	u8 key_schedule[AES256_EXPAND_KEY_LENGTH];
+	u8 selected_slot;
+	u32 selected_key_size;
+	bool key_expanded;
+};
+
+static int prepare_aes(struct sw_aes_priv *priv)
+{
+	if (!priv->selected_key_size) {
+		log_debug("%s: AES key size not set, setup a slot first\n", __func__);
+		return 1;
+	}
+
+	if (priv->key_expanded)
+		return 0;
+
+	priv->key_expanded = 1;
+
+	aes_expand_key(priv->key_slots[priv->selected_slot], priv->selected_key_size,
+		       priv->key_schedule);
+
+	return 0;
+}
+
+static int sw_aes_ops_available_key_slots(struct udevice *dev)
+{
+	return SW_KEY_SLOTS;
+}
+
+static int sw_aes_ops_select_key_slot(struct udevice *dev, u32 key_size, u8 slot)
+{
+	struct sw_aes_priv *priv = dev_get_priv(dev);
+
+	if (slot >= SW_KEY_SLOTS)
+		return 1;
+
+	priv->selected_slot = slot;
+	priv->selected_key_size = key_size;
+	priv->key_expanded = 0;
+
+	return 0;
+}
+
+static int sw_aes_ops_set_key_for_key_slot(struct udevice *dev, u32 key_size,
+					   u8 *key, u8 slot)
+{
+	struct sw_aes_priv *priv = dev_get_priv(dev);
+
+	if (slot >= SW_KEY_SLOTS)
+		return 1;
+
+	memcpy(priv->key_slots[slot], key, key_size / 8);
+
+	if (priv->selected_slot == slot)
+		priv->selected_key_size = key_size;
+
+	priv->key_expanded = 0;
+
+	return 0;
+}
+
+static int sw_aes_ops_aes_ecb_encrypt(struct udevice *dev, u8 *src, u8 *dst,
+				      u32 num_aes_blocks)
+{
+	struct sw_aes_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	ret = prepare_aes(priv);
+	if (ret)
+		return ret;
+
+	while (num_aes_blocks > 0) {
+		aes_encrypt(priv->selected_key_size, src, priv->key_schedule, dst);
+		num_aes_blocks -= 1;
+		src += AES_BLOCK_LENGTH;
+		dst += AES_BLOCK_LENGTH;
+	}
+
+	return 0;
+}
+
+static int sw_aes_ops_aes_ecb_decrypt(struct udevice *dev, u8 *src, u8 *dst,
+				      u32 num_aes_blocks)
+{
+	struct sw_aes_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	ret = prepare_aes(priv);
+	if (ret)
+		return ret;
+
+	while (num_aes_blocks > 0) {
+		aes_decrypt(priv->selected_key_size, src, priv->key_schedule, dst);
+		num_aes_blocks -= 1;
+		src += AES_BLOCK_LENGTH;
+		dst += AES_BLOCK_LENGTH;
+	}
+
+	return 0;
+}
+
+static int sw_aes_ops_aes_cbc_encrypt(struct udevice *dev, u8 *iv, u8 *src,
+				      u8 *dst, u32 num_aes_blocks)
+{
+	struct sw_aes_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	ret = prepare_aes(priv);
+	if (ret)
+		return ret;
+
+	aes_cbc_encrypt_blocks(priv->selected_key_size, priv->key_schedule, iv,
+			       src, dst, num_aes_blocks);
+
+	return 0;
+}
+
+static int sw_aes_ops_aes_cbc_decrypt(struct udevice *dev, u8 *iv, u8 *src,
+				      u8 *dst, u32 num_aes_blocks)
+{
+	struct sw_aes_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	ret = prepare_aes(priv);
+	if (ret)
+		return ret;
+
+	aes_cbc_decrypt_blocks(priv->selected_key_size, priv->key_schedule,
+			       iv, src, dst, num_aes_blocks);
+
+	return 0;
+}
+
+static const struct aes_ops aes_ops_sw = {
+	.available_key_slots = sw_aes_ops_available_key_slots,
+	.select_key_slot = sw_aes_ops_select_key_slot,
+	.set_key_for_key_slot = sw_aes_ops_set_key_for_key_slot,
+	.aes_ecb_encrypt = sw_aes_ops_aes_ecb_encrypt,
+	.aes_ecb_decrypt = sw_aes_ops_aes_ecb_decrypt,
+	.aes_cbc_encrypt = sw_aes_ops_aes_cbc_encrypt,
+	.aes_cbc_decrypt = sw_aes_ops_aes_cbc_decrypt,
+};
+
+static const struct udevice_id sw_aes_ids[] = {
+	{ .compatible = "software-aes-engine" },
+	{ }
+};
+
+U_BOOT_DRIVER(aes_sw) = {
+	.name = "aes_sw",
+	.id = UCLASS_AES,
+	.of_match = sw_aes_ids,
+	.ops = &aes_ops_sw,
+	.priv_auto = sizeof(struct sw_aes_priv),
+};