[PATCH 1/3] fdt: common API to populate kaslr seed

[seanedmond at linux.microsoft.com]

From: Dhananjay Phadke <dphadke at linux.microsoft.com>

fdt_fixup_kaslr_seed() will update given FDT with random seed value.
Source for random seed can be TPM or RNG driver in u-boot or sec
firmware (ARM).

Signed-off-by: Dhananjay Phadke <dphadke at linux.microsoft.com>
---
 arch/arm/cpu/armv8/sec_firmware.c | 32 +++++++------------------------
 common/fdt_support.c              | 31 ++++++++++++++++++++++++++++++
 include/fdt_support.h             |  3 +++
 3 files changed, 41 insertions(+), 25 deletions(-)

diff --git a/arch/arm/cpu/armv8/sec_firmware.c b/arch/arm/cpu/armv8/sec_firmware.c
index c0e8726346..84ba49924e 100644
--- a/arch/arm/cpu/armv8/sec_firmware.c
+++ b/arch/arm/cpu/armv8/sec_firmware.c
@@ -411,46 +411,28 @@ int sec_firmware_init(const void *sec_firmware_img,
 /*
  * fdt_fix_kaslr - Add kalsr-seed node in Device tree
  * @fdt:		Device tree
- * @eret:		0 in case of error, 1 for success
+ * @eret:		0 for success
  */
 int fdt_fixup_kaslr(void *fdt)
 {
-	int nodeoffset;
-	int err, ret = 0;
-	u8 rand[8];
+	int ret = 0;
 
 #if defined(CONFIG_ARMV8_SEC_FIRMWARE_SUPPORT)
+	u8 rand[8];
+
 	/* Check if random seed generation is  supported */
 	if (sec_firmware_support_hwrng() == false) {
 		printf("WARNING: SEC firmware not running, no kaslr-seed\n");
-		return 0;
+		return -EOPNOTSUPP;
 	}
 
 	err = sec_firmware_get_random(rand, 8);
 	if (err < 0) {
 		printf("WARNING: No random number to set kaslr-seed\n");
-		return 0;
-	}
-
-	err = fdt_check_header(fdt);
-	if (err < 0) {
-		printf("fdt_chosen: %s\n", fdt_strerror(err));
-		return 0;
+		return ret;
 	}
 
-	/* find or create "/chosen" node. */
-	nodeoffset = fdt_find_or_add_subnode(fdt, 0, "chosen");
-	if (nodeoffset < 0)
-		return 0;
-
-	err = fdt_setprop(fdt, nodeoffset, "kaslr-seed", rand,
-				  sizeof(rand));
-	if (err < 0) {
-		printf("WARNING: can't set kaslr-seed %s.\n",
-		       fdt_strerror(err));
-		return 0;
-	}
-	ret = 1;
+	ret = fdt_fixup_kaslr_seed(fdt, rand, sizeof(rand));
 #endif
 
 	return ret;
diff --git a/common/fdt_support.c b/common/fdt_support.c
index 5e49078f8c..35d4f26dbd 100644
--- a/common/fdt_support.c
+++ b/common/fdt_support.c
@@ -631,6 +631,37 @@ void fdt_fixup_ethernet(void *fdt)
 	}
 }
 
+/*
+ * fdt_fix_kaslr_seed - Add kalsr-seed node in Device tree
+ * @fdt:		Device tree
+ * @eret:		0 for success
+ */
+int fdt_fixup_kaslr_seed(void *fdt, const u8 *seed, int len)
+{
+	int nodeoffset;
+	int err;
+
+	err = fdt_check_header(fdt);
+	if (err < 0) {
+		printf("fdt_chosen: %s\n", fdt_strerror(err));
+		return err;
+	}
+
+	/* find or create "/chosen" node. */
+	nodeoffset = fdt_find_or_add_subnode(fdt, 0, "chosen");
+	if (nodeoffset < 0)
+		return -ENOENT;
+
+	err = fdt_setprop(fdt, nodeoffset, "kaslr-seed", seed, len);
+	if (err < 0) {
+		printf("WARNING: can't set kaslr-seed %s.\n",
+		       fdt_strerror(err));
+		return err;
+	}
+
+	return 0;
+}
+
 int fdt_record_loadable(void *blob, u32 index, const char *name,
 			uintptr_t load_addr, u32 size, uintptr_t entry_point,
 			const char *type, const char *os, const char *arch)
diff --git a/include/fdt_support.h b/include/fdt_support.h
index 2cd8366898..d74ef4e0a7 100644
--- a/include/fdt_support.h
+++ b/include/fdt_support.h
@@ -121,6 +121,9 @@ static inline int fdt_fixup_memory_banks(void *blob, u64 start[], u64 size[],
 #endif
 
 void fdt_fixup_ethernet(void *fdt);
+
+int fdt_fixup_kaslr_seed(void *fdt, const u8 *seed, int len);
+
 int fdt_find_and_setprop(void *fdt, const char *node, const char *prop,
 			 const void *val, int len, int create);
 void fdt_fixup_qe_firmware(void *fdt);
-- 
2.40.0