DM: crypto/rsa_mod_exp: Add rsa Modular Exponentiation DM driver

Add a new rsa uclass for performing modular exponentiation and implement
the software driver basing on this uclass.

Signed-off-by: Ruchika Gupta <ruchika.gupta@freescale.com>
CC: Simon Glass <sjg@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>

drivers/crypto/Makefile

@@ -6,4 +6,5 @@
 #
 
 obj-$(CONFIG_EXYNOS_ACE_SHA)	+= ace_sha.o
+obj-y += rsa_mod_exp/
 obj-y += fsl/

drivers/crypto/rsa_mod_exp/Kconfig

@@ -0,0 +1,5 @@
+config DM_MOD_EXP
+	bool "Enable Driver Model for RSA Modular Exponentiation"
+	depends on DM
+	help
+	  If you want to use driver model for RSA Modular Exponentiation, say Y.

drivers/crypto/rsa_mod_exp/Makefile

@@ -0,0 +1,7 @@
+#
+# (C) Copyright 2014 Freescale Semiconductor, Inc.
+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+obj-$(CONFIG_RSA) += mod_exp_uclass.o mod_exp_sw.o

drivers/crypto/rsa_mod_exp/mod_exp_sw.c

@@ -0,0 +1,39 @@
+/*
+ * (C) Copyright 2014 Freescale Semiconductor, Inc.
+ * Author: Ruchika Gupta <ruchika.gupta@freescale.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <config.h>
+#include <common.h>
+#include <dm.h>
+#include <u-boot/rsa-mod-exp.h>
+
+int mod_exp_sw(struct udevice *dev, const uint8_t *sig, uint32_t sig_len,
+		struct key_prop *prop, uint8_t *out)
+{
+	int ret = 0;
+
+	ret = rsa_mod_exp_sw(sig, sig_len, prop, out);
+	if (ret) {
+		debug("%s: RSA failed to verify: %d\n", __func__, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct mod_exp_ops mod_exp_ops_sw = {
+	.mod_exp	= mod_exp_sw,
+};
+
+U_BOOT_DRIVER(mod_exp_sw) = {
+	.name	= "mod_exp_sw",
+	.id	= UCLASS_MOD_EXP,
+	.ops	= &mod_exp_ops_sw,
+};
+
+U_BOOT_DEVICE(mod_exp_sw) = {
+	.name = "mod_exp_sw",
+};

drivers/crypto/rsa_mod_exp/mod_exp_uclass.c

@@ -0,0 +1,31 @@
+/*
+ * (C) Copyright 2014 Freescale Semiconductor, Inc
+ * Author: Ruchika Gupta <ruchika.gupta@freescale.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <u-boot/rsa-mod-exp.h>
+#include <errno.h>
+#include <fdtdec.h>
+#include <malloc.h>
+#include <asm/io.h>
+#include <linux/list.h>
+
+int rsa_mod_exp(struct udevice *dev, const uint8_t *sig, uint32_t sig_len,
+		struct key_prop *node, uint8_t *out)
+{
+	const struct mod_exp_ops *ops = device_get_ops(dev);
+
+	if (!ops->mod_exp)
+		return -ENOSYS;
+
+	return ops->mod_exp(dev, sig, sig_len, node, out);
+}
+
+UCLASS_DRIVER(mod_exp) = {
+	.id		= UCLASS_MOD_EXP,
+	.name		= "rsa_mod_exp",
+};

include/dm/uclass-id.h

@@ -33,6 +33,7 @@ enum uclass_id {
 	UCLASS_I2C,		/* I2C bus */
 	UCLASS_I2C_GENERIC,	/* Generic I2C device */
 	UCLASS_I2C_EEPROM,	/* I2C EEPROM device */
+	UCLASS_MOD_EXP,		/* RSA Mod Exp device */
 
 	UCLASS_COUNT,
 	UCLASS_INVALID = -1,

include/u-boot/rsa-mod-exp.h

@@ -35,9 +35,41 @@ struct key_prop {
  * @sig:	RSA PKCS1.5 signature
  * @sig_len:	Length of signature in number of bytes
  * @node:	Node with RSA key elements like modulus, exponent, R^2, n0inv
- * @out:	Result in form of byte array
+ * @out:	Result in form of byte array of len equal to sig_len
  */
 int rsa_mod_exp_sw(const uint8_t *sig, uint32_t sig_len,
 		struct key_prop *node, uint8_t *out);
 
+int rsa_mod_exp(struct udevice *dev, const uint8_t *sig, uint32_t sig_len,
+		struct key_prop *node, uint8_t *out);
+
+/**
+ * struct struct mod_exp_ops - Driver model for RSA Modular Exponentiation
+ *				operations
+ *
+ * The uclass interface is implemented by all crypto devices which use
+ * driver model.
+ */
+struct mod_exp_ops {
+	/**
+	 * Perform Modular Exponentiation
+	 *
+	 * Operation: out[] = sig ^ exponent % modulus
+	 *
+	 * @dev:	RSA Device
+	 * @sig:	RSA PKCS1.5 signature
+	 * @sig_len:	Length of signature in number of bytes
+	 * @node:	Node with RSA key elements like modulus, exponent,
+	 *		R^2, n0inv
+	 * @out:	Result in form of byte array of len equal to sig_len
+	 *
+	 * This function computes exponentiation over the signature.
+	 * Returns: 0 if exponentiation is successful, or a negative value
+	 * if it wasn't.
+	 */
+	int (*mod_exp)(struct udevice *dev, const uint8_t *sig,
+			   uint32_t sig_len, struct key_prop *node,
+			   uint8_t *outp);
+};
+
 #endif