From d072bfa4885354fff86aa1fb1dbc4f1533c9e0bf Mon Sep 17 00:00:00 2001
From: Christian Lamparter <chunkeey@gmail.com>
Date: Sun, 23 Dec 2018 02:16:13 +0100
Subject: [PATCH 06/15] crypto: crypto4xx - add prng crypto support

This patch adds support for crypto4xx's ANSI X9.17 Annex C compliant
pseudo random number generator which provides a pseudo random source
for the purpose of generating  Initialization Vectors (IV's) for AES
algorithms to the Packet Engine and other pseudo random number
requirements.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
 drivers/crypto/amcc/crypto4xx_core.c    | 87 +++++++++++++++++++++++++
 drivers/crypto/amcc/crypto4xx_core.h    |  4 ++
 drivers/crypto/amcc/crypto4xx_reg_def.h |  1 +
 3 files changed, 92 insertions(+)

--- a/drivers/crypto/amcc/crypto4xx_core.c
+++ b/drivers/crypto/amcc/crypto4xx_core.c
@@ -40,9 +40,11 @@
 #include <crypto/ctr.h>
 #include <crypto/gcm.h>
 #include <crypto/sha.h>
+#include <crypto/rng.h>
 #include <crypto/scatterwalk.h>
 #include <crypto/skcipher.h>
 #include <crypto/internal/aead.h>
+#include <crypto/internal/rng.h>
 #include <crypto/internal/skcipher.h>
 #include "crypto4xx_reg_def.h"
 #include "crypto4xx_core.h"
@@ -1035,6 +1037,10 @@ static int crypto4xx_register_alg(struct
 			rc = crypto_register_ahash(&alg->alg.u.hash);
 			break;
 
+		case CRYPTO_ALG_TYPE_RNG:
+			rc = crypto_register_rng(&alg->alg.u.rng);
+			break;
+
 		default:
 			rc = crypto_register_skcipher(&alg->alg.u.cipher);
 			break;
@@ -1064,6 +1070,10 @@ static void crypto4xx_unregister_alg(str
 			crypto_unregister_aead(&alg->alg.u.aead);
 			break;
 
+		case CRYPTO_ALG_TYPE_RNG:
+			crypto_unregister_rng(&alg->alg.u.rng);
+			break;
+
 		default:
 			crypto_unregister_skcipher(&alg->alg.u.cipher);
 		}
@@ -1122,6 +1132,69 @@ static irqreturn_t crypto4xx_ce_interrup
 		PPC4XX_TMO_ERR_INT);
 }
 
+static int ppc4xx_prng_data_read(struct crypto4xx_device *dev,
+				 u8 *data, unsigned int max)
+{
+	unsigned int i, curr = 0;
+	u32 val[2];
+
+	do {
+		/* trigger PRN generation */
+		writel(PPC4XX_PRNG_CTRL_AUTO_EN,
+		       dev->ce_base + CRYPTO4XX_PRNG_CTRL);
+
+		for (i = 0; i < 1024; i++) {
+			/* usually 19 iterations are enough */
+			if ((readl(dev->ce_base + CRYPTO4XX_PRNG_STAT) &
+			     CRYPTO4XX_PRNG_STAT_BUSY))
+				continue;
+
+			val[0] = readl_be(dev->ce_base + CRYPTO4XX_PRNG_RES_0);
+			val[1] = readl_be(dev->ce_base + CRYPTO4XX_PRNG_RES_1);
+			break;
+		}
+		if (i == 1024)
+			return -ETIMEDOUT;
+
+		if ((max - curr) >= 8) {
+			memcpy(data, &val, 8);
+			data += 8;
+			curr += 8;
+		} else {
+			/* copy only remaining bytes */
+			memcpy(data, &val, max - curr);
+			break;
+		}
+	} while (curr < max);
+
+	return curr;
+}
+
+static int crypto4xx_prng_generate(struct crypto_rng *tfm,
+				   const u8 *src, unsigned int slen,
+				   u8 *dstn, unsigned int dlen)
+{
+	struct rng_alg *alg = crypto_rng_alg(tfm);
+	struct crypto4xx_alg *amcc_alg;
+	struct crypto4xx_device *dev;
+	int ret;
+
+	amcc_alg = container_of(alg, struct crypto4xx_alg, alg.u.rng);
+	dev = amcc_alg->dev;
+
+	mutex_lock(&dev->core_dev->rng_lock);
+	ret = ppc4xx_prng_data_read(dev, dstn, dlen);
+	mutex_unlock(&dev->core_dev->rng_lock);
+	return ret;
+}
+
+
+static int crypto4xx_prng_seed(struct crypto_rng *tfm, const u8 *seed,
+			unsigned int slen)
+{
+	return 0;
+}
+
 /**
  * Supported Crypto Algorithms
  */
@@ -1291,6 +1364,18 @@ static struct crypto4xx_alg_common crypt
 			.cra_module	= THIS_MODULE,
 		},
 	} },
+	{ .type = CRYPTO_ALG_TYPE_RNG, .u.rng = {
+		.base = {
+			.cra_name		= "stdrng",
+			.cra_driver_name        = "crypto4xx_rng",
+			.cra_priority		= 300,
+			.cra_ctxsize		= 0,
+			.cra_module		= THIS_MODULE,
+		},
+		.generate               = crypto4xx_prng_generate,
+		.seed                   = crypto4xx_prng_seed,
+		.seedsize               = 0,
+	} },
 };
 
 /**
@@ -1360,6 +1445,7 @@ static int crypto4xx_probe(struct platfo
 	core_dev->dev->core_dev = core_dev;
 	core_dev->dev->is_revb = is_revb;
 	core_dev->device = dev;
+	mutex_init(&core_dev->rng_lock);
 	spin_lock_init(&core_dev->lock);
 	INIT_LIST_HEAD(&core_dev->dev->alg_list);
 	ratelimit_default_init(&core_dev->dev->aead_ratelimit);
@@ -1439,6 +1525,7 @@ static int crypto4xx_remove(struct platf
 	tasklet_kill(&core_dev->tasklet);
 	/* Un-register with Linux CryptoAPI */
 	crypto4xx_unregister_alg(core_dev->dev);
+	mutex_destroy(&core_dev->rng_lock);
 	/* Free all allocated memory */
 	crypto4xx_stop_all(core_dev);
 
--- a/drivers/crypto/amcc/crypto4xx_core.h
+++ b/drivers/crypto/amcc/crypto4xx_core.h
@@ -23,8 +23,10 @@
 #define __CRYPTO4XX_CORE_H__
 
 #include <linux/ratelimit.h>
+#include <linux/mutex.h>
 #include <crypto/internal/hash.h>
 #include <crypto/internal/aead.h>
+#include <crypto/internal/rng.h>
 #include <crypto/internal/skcipher.h>
 #include "crypto4xx_reg_def.h"
 #include "crypto4xx_sa.h"
@@ -119,6 +121,7 @@ struct crypto4xx_core_device {
 	u32 irq;
 	struct tasklet_struct tasklet;
 	spinlock_t lock;
+	struct mutex rng_lock;
 };
 
 struct crypto4xx_ctx {
@@ -143,6 +146,7 @@ struct crypto4xx_alg_common {
 		struct skcipher_alg cipher;
 		struct ahash_alg hash;
 		struct aead_alg aead;
+		struct rng_alg rng;
 	} u;
 };
 
--- a/drivers/crypto/amcc/crypto4xx_reg_def.h
+++ b/drivers/crypto/amcc/crypto4xx_reg_def.h
@@ -100,6 +100,7 @@
 #define CRYPTO4XX_ENDIAN_CFG			0x000600d8
 
 #define CRYPTO4XX_PRNG_STAT			0x00070000
+#define CRYPTO4XX_PRNG_STAT_BUSY		0x1
 #define CRYPTO4XX_PRNG_CTRL			0x00070004
 #define CRYPTO4XX_PRNG_SEED_L			0x00070008
 #define CRYPTO4XX_PRNG_SEED_H			0x0007000c
