[PATCH v3 09/10] crypto: hash: allow DM hash in SPL

[James Hilliard]

The hash uclass is currently keyed only by CONFIG_DM_HASH, so SPL cannot
enable UCLASS_HASH independently. Any SPL code using hash_digest*() has to
rely on U-Boot proper also enabling DM_HASH, and the FIT hash path selects
the driver-model implementation with a non-phase-aware preprocessor check.

Add SPL_DM_HASH, build the hash uclass from CONFIG_$(PHASE_)DM_HASH and use
CONFIG_IS_ENABLED(DM_HASH) when selecting the FIT hash implementation. This
lets SPL FIT verification use a UCLASS_HASH provider without requiring the
U-Boot proper hash uclass.

Signed-off-by: James Hilliard <james.hilliard1 at gmail.com>
---
Changes v2 -> v3:
  - Remove the bare software-hash fallback scope  (suggested by Simon Glass)
  - Document that SPL_DM_HASH needs a hardware provider unless a phase-aware
    software hash provider is added  (suggested by Simon Glass)
---
 boot/image-fit.c             | 50 +++++++++++++++++++++++---------------------
 drivers/crypto/hash/Kconfig  | 13 ++++++++++++
 drivers/crypto/hash/Makefile |  2 +-
 3 files changed, 40 insertions(+), 25 deletions(-)

diff --git a/boot/image-fit.c b/boot/image-fit.c
index c84cbfaf4a8..e38d84c361f 100644
--- a/boot/image-fit.c
+++ b/boot/image-fit.c
@@ -32,10 +32,8 @@ extern void *aligned_alloc(size_t alignment, size_t size);
 #include <malloc.h>
 #include <memalign.h>
 #include <asm/global_data.h>
-#ifdef CONFIG_DM_HASH
 #include <dm.h>
 #include <u-boot/hash.h>
-#endif
 #define aligned_alloc(a, s)	memalign((a), (s))
 
 DECLARE_GLOBAL_DATA_PTR;
@@ -1321,43 +1319,47 @@ int fit_set_timestamp(void *fit, int noffset, time_t timestamp)
 int calculate_hash(const void *data, int data_len, const char *name,
 			uint8_t *value, int *value_len)
 {
-#if !defined(USE_HOSTCC) && defined(CONFIG_DM_HASH)
+	struct hash_algo *algo;
+	int ret;
+
+#ifndef USE_HOSTCC
 	int rc;
 	enum HASH_ALGO hash_algo;
 	struct udevice *dev;
 
-	rc = uclass_get_device(UCLASS_HASH, 0, &dev);
-	if (rc) {
-		debug("failed to get hash device, rc=%d\n", rc);
-		return -1;
-	}
+	if (CONFIG_IS_ENABLED(DM_HASH)) {
+		rc = uclass_get_device(UCLASS_HASH, 0, &dev);
+		if (rc) {
+			debug("failed to get hash device, rc=%d\n", rc);
+			return -1;
+		}
 
-	hash_algo = hash_algo_lookup_by_name(name);
-	if (hash_algo == HASH_ALGO_INVALID) {
-		debug("Unsupported hash algorithm\n");
-		return -1;
-	};
+		hash_algo = hash_algo_lookup_by_name(name);
+		if (hash_algo == HASH_ALGO_INVALID) {
+			debug("Unsupported hash algorithm\n");
+			return -1;
+		}
 
-	rc = hash_digest_wd(dev, hash_algo, data, data_len, value, CHUNKSZ);
-	if (rc) {
-		debug("failed to get hash value, rc=%d\n", rc);
-		return -1;
-	}
+		rc = hash_digest_wd(dev, hash_algo, data, data_len, value,
+				    CHUNKSZ);
+		if (rc) {
+			debug("failed to get hash value, rc=%d\n", rc);
+			return -1;
+		}
 
-	*value_len = hash_algo_digest_size(hash_algo);
-#else
-	struct hash_algo *algo;
-	int ret;
+		*value_len = hash_algo_digest_size(hash_algo);
+		return 0;
+	}
+#endif
 
 	ret = hash_lookup_algo(name, &algo);
 	if (ret < 0) {
-		debug("Unsupported hash alogrithm\n");
+		debug("Unsupported hash algorithm\n");
 		return -1;
 	}
 
 	algo->hash_func_ws(data, data_len, value, algo->chunk_size);
 	*value_len = algo->digest_size;
-#endif
 
 	return 0;
 }
diff --git a/drivers/crypto/hash/Kconfig b/drivers/crypto/hash/Kconfig
index 72b955ac791..272af7bce18 100644
--- a/drivers/crypto/hash/Kconfig
+++ b/drivers/crypto/hash/Kconfig
@@ -4,6 +4,19 @@ config DM_HASH
 	help
 	  If you want to use driver model for Hash, say Y.
 
+config SPL_DM_HASH
+	bool "Enable Driver Model for Hash in SPL"
+	depends on SPL_DM
+	select SPL_CRYPTO
+	help
+	  Enable the hash uclass in SPL so SPL code can bind and use
+	  UCLASS_HASH providers through the driver model. This is useful for
+	  FIT verification paths that want to calculate image hashes through a
+	  hardware hash accelerator before U-Boot proper is loaded.
+	  HASH_SOFTWARE depends on DM_HASH, so SPL_DM_HASH alone does not
+	  provide a software hash device. Enable a hardware hash provider for
+	  SPL when selecting this option.
+
 config HASH_SOFTWARE
 	bool "Enable driver for Hash in software"
 	depends on DM_HASH
diff --git a/drivers/crypto/hash/Makefile b/drivers/crypto/hash/Makefile
index 33d88161ed4..9f0d30f9be3 100644
--- a/drivers/crypto/hash/Makefile
+++ b/drivers/crypto/hash/Makefile
@@ -2,5 +2,5 @@
 #
 # Copyright (c) 2021 ASPEED Technology Inc.
 
-obj-$(CONFIG_DM_HASH) += hash-uclass.o
+obj-$(CONFIG_$(PHASE_)DM_HASH) += hash-uclass.o
 obj-$(CONFIG_HASH_SOFTWARE) += hash_sw.o

-- 
2.53.0