[PATCH v6 0/3] efi_vars: Implement SPI Flash storage for EFI

[PATCH v6 0/3] efi_vars: Implement SPI Flash storage for EFI

[Michal Simek]

This is updated series based on v3 version sent here
https://lore.kernel.org/all/20231126220836.374956-1-i@shantur.com/

that's why I am continuing on v4 instead of starting from scratch.

Tested on kv260 with saving variables to location where User MTD partition
is.
CONFIG_EFI_VARIABLE_SF_STORE=y
CONFIG_EFI_RT_VOLATILE_STORE=y
CONFIG_EFI_VARIABLE_SF_OFFSET=0x22a0000

In Linux:
root@som:~# mount | grep efivars
none on /sys/firmware/efi/efivars type efivarfs (rw,relatime)
root@som:~# printf '\x07\x00\x00\x00Hello' \
  | sudo tee /sys/firmware/efi/efivars/TestVar-12345678-1234-1234-1234-123456789abc
Helloroot@som:~#
root@som:~# dd if=/sys/firmware/efi/efivars/VarToFile-b2ac5fc9-92b7-4acd-aeac-11e818c3130c \
       of=/tmp/vars skip=4 bs=1
1352+0 records in
1352+0 records out
1352 bytes (1.4 kB, 1.3 KiB) copied, 0.380992 s, 3.5 kB/s
root@som:~# flashcp /tmp/vars /dev/mtd16
root@som:~# reboot

Reboot and then in U-Boot:

ZynqMP> pri -e
...
TestVar:
    12345678-1234-1234-1234-123456789abc (12345678-1234-1234-1234-123456789abc)
    NV|BS|RT, DataSize = 0x5
    00000000: 48 65 6c 6c 6f                                   Hello
...

Thanks,
Michal

Changes in v6:
- Return EFI_SUCCESS in efi_set_variable_int() when
  CONFIG_EFI_VARIABLE_NO_STORE is enabled
- sed -i 's/efi_var_read/efi_var_from/g'
- sed -i 's/efi_var_write/efi_var_to_storage/g'
- sed -i 's/efi_var_read/efi_var_from/g'
- sed -i 's/efi_var_write/efi_var_to_storage/g'

Changes in v5:
- Invert logic in efi_variable.c and avoid #if

Changes in v4:
- New patch based on review comments from v3
- Extend Kconfig description
- Extend commit message and describe efivar missing part
- use unify methods for reading/writing variable

Changes in v3:
- Fixed compiler warnings.

Changes in v2:
- Refactored efi_var_file to move common parts out as requested
- Changed ifdefs to use CONFIG_IS_DEFINED
- Fixed typos

Michal Simek (1):
  efi_var: Unify read/write access helper function

Shantur Rathore (2):
  efi_var_file: refactor to move buffer functions
  efi_vars: Implement SPI Flash store

 include/efi_variable.h          | 18 +++----
 lib/efi_loader/Kconfig          | 34 +++++++++++-
 lib/efi_loader/Makefile         |  3 +-
 lib/efi_loader/efi_var_common.c | 42 +++++++++++++++
 lib/efi_loader/efi_var_file.c   | 65 ++---------------------
 lib/efi_loader/efi_var_sf.c     | 92 +++++++++++++++++++++++++++++++++
 lib/efi_loader/efi_variable.c   | 19 ++++---
 7 files changed, 195 insertions(+), 78 deletions(-)
 create mode 100644 lib/efi_loader/efi_var_sf.c

-- 
2.43.0

base-commit: e206e3ab2ad266935b81f5e9d3af2ed47b866826

[PATCH v6 1/3] efi_var_file: refactor to move buffer functions

[Michal Simek]

From: Shantur Rathore <i@shantur.com>

Currently efi_var_file.c has functions to store/read
EFI variables to/from memory buffer. These functions
can be used with other EFI variable stores so move
them out to efi_var_common.c

Signed-off-by: Shantur Rathore <i@shantur.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
---

Changes in v6:
- Return EFI_SUCCESS in efi_set_variable_int() when
  CONFIG_EFI_VARIABLE_NO_STORE is enabled

Changes in v5:
- Invert logic in efi_variable.c and avoid #if

 include/efi_variable.h          |  5 +++
 lib/efi_loader/Makefile         |  2 +-
 lib/efi_loader/efi_var_common.c | 42 ++++++++++++++++++++++++
 lib/efi_loader/efi_var_file.c   | 57 ---------------------------------
 lib/efi_loader/efi_variable.c   | 17 +++++++---
 5 files changed, 60 insertions(+), 63 deletions(-)

diff --git a/include/efi_variable.h b/include/efi_variable.h
index 4065cf45ecaf..ee68fa4a885f 100644
--- a/include/efi_variable.h
+++ b/include/efi_variable.h
@@ -161,6 +161,11 @@ efi_status_t efi_var_to_file(void);
 efi_status_t __maybe_unused efi_var_collect(struct efi_var_file **bufp, loff_t *lenp,
 					    u32 check_attr_mask);
 
+/* GUID used by Shim to store the MOK database */
+#define SHIM_LOCK_GUID \
+	EFI_GUID(0x605dab50, 0xe046, 0x4300, \
+		 0xab, 0xb6, 0x3d, 0xd8, 0x10, 0xdd, 0x8b, 0x23)
+
 /**
  * efi_var_restore() - restore EFI variables from buffer
  *
diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
index f490081f6542..ca1775eb03be 100644
--- a/lib/efi_loader/Makefile
+++ b/lib/efi_loader/Makefile
@@ -53,7 +53,7 @@ ifeq ($(CONFIG_EFI_MM_COMM_TEE),y)
 obj-y += efi_variable_tee.o
 else
 obj-y += efi_variable.o
-obj-y += efi_var_file.o
+obj-$(CONFIG_EFI_VARIABLE_FILE_STORE) += efi_var_file.o
 obj-$(CONFIG_EFI_VARIABLES_PRESEED) += efi_var_seed.o
 endif
 obj-y += efi_watchdog.o
diff --git a/lib/efi_loader/efi_var_common.c b/lib/efi_loader/efi_var_common.c
index 4b34a58b4cf7..5ea1688dca3d 100644
--- a/lib/efi_loader/efi_var_common.c
+++ b/lib/efi_loader/efi_var_common.c
@@ -41,6 +41,7 @@ static const struct efi_auth_var_name_type name_type[] = {
 
 static bool efi_secure_boot;
 static enum efi_secure_mode efi_secure_mode;
+static const efi_guid_t shim_lock_guid = SHIM_LOCK_GUID;
 
 /**
  * efi_efi_get_variable() - retrieve value of a UEFI variable
@@ -488,3 +489,44 @@ efi_status_t __maybe_unused efi_var_collect(struct efi_var_file **bufp, loff_t *
 
 	return EFI_SUCCESS;
 }
+
+efi_status_t efi_var_restore(struct efi_var_file *buf, bool safe)
+{
+	struct efi_var_entry *var, *last_var;
+	u16 *data;
+	efi_status_t ret;
+
+	if (buf->reserved || buf->magic != EFI_VAR_FILE_MAGIC ||
+	    buf->crc32 != crc32(0, (u8 *)buf->var,
+				buf->length - sizeof(struct efi_var_file))) {
+		log_err("Invalid EFI variables file\n");
+		return EFI_INVALID_PARAMETER;
+	}
+
+	last_var = (struct efi_var_entry *)((u8 *)buf + buf->length);
+	for (var = buf->var; var < last_var;
+	     var = (struct efi_var_entry *)ALIGN((uintptr_t)data + var->length, 8)) {
+		data = var->name + u16_strlen(var->name) + 1;
+
+		/*
+		 * Secure boot related and volatile variables shall only be
+		 * restored from U-Boot's preseed.
+		 */
+		if (!safe &&
+		    (efi_auth_var_get_type(var->name, &var->guid) !=
+		     EFI_AUTH_VAR_NONE ||
+		     !guidcmp(&var->guid, &shim_lock_guid) ||
+		     !(var->attr & EFI_VARIABLE_NON_VOLATILE)))
+			continue;
+		if (!var->length)
+			continue;
+		if (efi_var_mem_find(&var->guid, var->name, NULL))
+			continue;
+		ret = efi_var_mem_ins(var->name, &var->guid, var->attr,
+				      var->length, data, 0, NULL,
+				      var->time);
+		if (ret != EFI_SUCCESS)
+			log_err("Failed to set EFI variable %ls\n", var->name);
+	}
+	return EFI_SUCCESS;
+}
diff --git a/lib/efi_loader/efi_var_file.c b/lib/efi_loader/efi_var_file.c
index ba0bf33ffbd1..d32edaac277d 100644
--- a/lib/efi_loader/efi_var_file.c
+++ b/lib/efi_loader/efi_var_file.c
@@ -14,17 +14,9 @@
 #include <mapmem.h>
 #include <efi_loader.h>
 #include <efi_variable.h>
-#include <u-boot/crc.h>
 
 #define PART_STR_LEN 10
 
-/* GUID used by Shim to store the MOK database */
-#define SHIM_LOCK_GUID \
-	EFI_GUID(0x605dab50, 0xe046, 0x4300, \
-		 0xab, 0xb6, 0x3d, 0xd8, 0x10, 0xdd, 0x8b, 0x23)
-
-static const efi_guid_t shim_lock_guid = SHIM_LOCK_GUID;
-
 /**
  * efi_set_blk_dev_to_system_partition() - select EFI system partition
  *
@@ -59,7 +51,6 @@ static efi_status_t __maybe_unused efi_set_blk_dev_to_system_partition(void)
  */
 efi_status_t efi_var_to_file(void)
 {
-#ifdef CONFIG_EFI_VARIABLE_FILE_STORE
 	efi_status_t ret;
 	struct efi_var_file *buf;
 	loff_t len;
@@ -91,52 +82,6 @@ error:
 out:
 	free(buf);
 	return ret;
-#else
-	return EFI_SUCCESS;
-#endif
-}
-
-efi_status_t efi_var_restore(struct efi_var_file *buf, bool safe)
-{
-	struct efi_var_entry *var, *last_var;
-	u16 *data;
-	efi_status_t ret;
-
-	if (buf->reserved || buf->magic != EFI_VAR_FILE_MAGIC ||
-	    buf->crc32 != crc32(0, (u8 *)buf->var,
-				buf->length - sizeof(struct efi_var_file))) {
-		log_err("Invalid EFI variables file\n");
-		return EFI_INVALID_PARAMETER;
-	}
-
-	last_var = (struct efi_var_entry *)((u8 *)buf + buf->length);
-	for (var = buf->var; var < last_var;
-	     var = (struct efi_var_entry *)
-		   ALIGN((uintptr_t)data + var->length, 8)) {
-
-		data = var->name + u16_strlen(var->name) + 1;
-
-		/*
-		 * Secure boot related and volatile variables shall only be
-		 * restored from U-Boot's preseed.
-		 */
-		if (!safe &&
-		    (efi_auth_var_get_type(var->name, &var->guid) !=
-		     EFI_AUTH_VAR_NONE ||
-		     !guidcmp(&var->guid, &shim_lock_guid) ||
-		     !(var->attr & EFI_VARIABLE_NON_VOLATILE)))
-			continue;
-		if (!var->length)
-			continue;
-		if (efi_var_mem_find(&var->guid, var->name, NULL))
-			continue;
-		ret = efi_var_mem_ins(var->name, &var->guid, var->attr,
-				      var->length, data, 0, NULL,
-				      var->time);
-		if (ret != EFI_SUCCESS)
-			log_err("Failed to set EFI variable %ls\n", var->name);
-	}
-	return EFI_SUCCESS;
 }
 
 /**
@@ -155,7 +100,6 @@ efi_status_t efi_var_restore(struct efi_var_file *buf, bool safe)
  */
 efi_status_t efi_var_from_file(void)
 {
-#ifdef CONFIG_EFI_VARIABLE_FILE_STORE
 	struct efi_var_file *buf;
 	loff_t len;
 	efi_status_t ret;
@@ -180,6 +124,5 @@ efi_status_t efi_var_from_file(void)
 		log_err("Invalid EFI variables file\n");
 error:
 	free(buf);
-#endif
 	return EFI_SUCCESS;
 }
diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
index f3533f4def3a..6e45134c61bf 100644
--- a/lib/efi_loader/efi_variable.c
+++ b/lib/efi_loader/efi_variable.c
@@ -397,11 +397,15 @@ efi_status_t efi_set_variable_int(const u16 *variable_name,
 		ret = EFI_SUCCESS;
 
 	/*
-	 * Write non-volatile EFI variables to file
+	 * Write non-volatile EFI variables
 	 * TODO: check if a value change has occured to avoid superfluous writes
 	 */
-	if (attributes & EFI_VARIABLE_NON_VOLATILE)
+	if (attributes & EFI_VARIABLE_NON_VOLATILE) {
+		if (IS_ENABLED(CONFIG_EFI_VARIABLE_NO_STORE))
+			return EFI_SUCCESS;
+
 		efi_var_to_file();
+	}
 
 	return EFI_SUCCESS;
 }
@@ -594,9 +598,12 @@ efi_status_t efi_init_variables(void)
 	if (ret != EFI_SUCCESS)
 		return ret;
 
-	ret = efi_var_from_file();
-	if (ret != EFI_SUCCESS)
-		return ret;
+	if (!IS_ENABLED(CONFIG_EFI_VARIABLE_NO_STORE)) {
+		ret = efi_var_from_file();
+		if (ret != EFI_SUCCESS)
+			return ret;
+	}
+
 	if (IS_ENABLED(CONFIG_EFI_VARIABLES_PRESEED)) {
 		ret = efi_var_restore((struct efi_var_file *)
 				      __efi_var_file_begin, true);
-- 
2.43.0

[PATCH v6 2/3] efi_var: Unify read/write access helper function

[Michal Simek]

efi_var_to/from_file() suggest method where variables are placed. But there
is no reason for it and generic name can be used to wire also different
locations for variables.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
---

Changes in v6:
- sed -i 's/efi_var_read/efi_var_from/g'
- sed -i 's/efi_var_write/efi_var_to_storage/g'

Changes in v4:
- New patch based on review comments from v3

 include/efi_variable.h        | 13 ++++---------
 lib/efi_loader/efi_var_file.c |  8 ++++----
 lib/efi_loader/efi_variable.c |  4 ++--
 3 files changed, 10 insertions(+), 15 deletions(-)

diff --git a/include/efi_variable.h b/include/efi_variable.h
index ee68fa4a885f..2b06505b8654 100644
--- a/include/efi_variable.h
+++ b/include/efi_variable.h
@@ -137,13 +137,11 @@ struct efi_var_file {
 };
 
 /**
- * efi_var_to_file() - save non-volatile variables as file
- *
- * File ubootefi.var is created on the EFI system partion.
+ * efi_var_to_storage() - save non-volatile variables
  *
  * Return:	status code
  */
-efi_status_t efi_var_to_file(void);
+efi_status_t efi_var_to_storage(void);
 
 /**
  * efi_var_collect() - collect variables in buffer
@@ -178,17 +176,14 @@ efi_status_t __maybe_unused efi_var_collect(struct efi_var_file **bufp, loff_t *
 efi_status_t efi_var_restore(struct efi_var_file *buf, bool safe);
 
 /**
- * efi_var_from_file() - read variables from file
- *
- * File ubootefi.var is read from the EFI system partitions and the variables
- * stored in the file are created.
+ * efi_var_from() - read variables
  *
  * In case the file does not exist yet or a variable cannot be set EFI_SUCCESS
  * is returned.
  *
  * Return:	status code
  */
-efi_status_t efi_var_from_file(void);
+efi_status_t efi_var_from(void);
 
 /**
  * efi_var_mem_init() - set-up variable list
diff --git a/lib/efi_loader/efi_var_file.c b/lib/efi_loader/efi_var_file.c
index d32edaac277d..d012d6a18b02 100644
--- a/lib/efi_loader/efi_var_file.c
+++ b/lib/efi_loader/efi_var_file.c
@@ -43,13 +43,13 @@ static efi_status_t __maybe_unused efi_set_blk_dev_to_system_partition(void)
 }
 
 /**
- * efi_var_to_file() - save non-volatile variables as file
+ * efi_var_to_storage() - save non-volatile variables as file
  *
  * File ubootefi.var is created on the EFI system partion.
  *
  * Return:	status code
  */
-efi_status_t efi_var_to_file(void)
+efi_status_t efi_var_to_storage(void)
 {
 	efi_status_t ret;
 	struct efi_var_file *buf;
@@ -85,7 +85,7 @@ out:
 }
 
 /**
- * efi_var_from_file() - read variables from file
+ * efi_var_from() - read variables from file
  *
  * File ubootefi.var is read from the EFI system partitions and the variables
  * stored in the file are created.
@@ -98,7 +98,7 @@ out:
  *
  * Return:	status code
  */
-efi_status_t efi_var_from_file(void)
+efi_status_t efi_var_from(void)
 {
 	struct efi_var_file *buf;
 	loff_t len;
diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
index 6e45134c61bf..42f3ba901556 100644
--- a/lib/efi_loader/efi_variable.c
+++ b/lib/efi_loader/efi_variable.c
@@ -404,7 +404,7 @@ efi_status_t efi_set_variable_int(const u16 *variable_name,
 		if (IS_ENABLED(CONFIG_EFI_VARIABLE_NO_STORE))
 			return EFI_SUCCESS;
 
-		efi_var_to_file();
+		efi_var_to_storage();
 	}
 
 	return EFI_SUCCESS;
@@ -599,7 +599,7 @@ efi_status_t efi_init_variables(void)
 		return ret;
 
 	if (!IS_ENABLED(CONFIG_EFI_VARIABLE_NO_STORE)) {
-		ret = efi_var_from_file();
+		ret = efi_var_from();
 		if (ret != EFI_SUCCESS)
 			return ret;
 	}
-- 
2.43.0

[PATCH v6 3/3] efi_vars: Implement SPI Flash store

[Michal Simek]

From: Shantur Rathore <i@shantur.com>

Currently U-Boot uses ESP as storage for EFI variables.
Devices with SPI Flash are used for storing environment with this
commit we allow EFI variables to be stored on SPI Flash.

https://github.com/rhboot/efivar
is not updated to support this location that's why you can mimic it by
running:
dd if=/sys/firmware/efi/efivars/VarToFile-b2ac5fc9-92b7-4acd-aeac-11e818c3130c \
   of=/tmp/vars skip=4 bs=1
flashcp /tmp/vars /dev/mtdX

where mtdX should match location defined by
CONFIG_EFI_VARIABLE_SF_OFFSET/CONFIG_EFI_VAR_BUF_SIZE.

Signed-off-by: Shantur Rathore <i@shantur.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
---

Changes in v6:
- sed -i 's/efi_var_read/efi_var_from/g'
- sed -i 's/efi_var_write/efi_var_to_storage/g'

Changes in v4:
- Extend Kconfig description
- Extend commit message and describe efivar missing part
- use unify methods for reading/writing variable

Changes in v3:
- Fixed compiler warnings.

Changes in v2:
- Refactored efi_var_file to move common parts out as requested
- Changed ifdefs to use CONFIG_IS_DEFINED
- Fixed typos

 lib/efi_loader/Kconfig      | 34 +++++++++++++-
 lib/efi_loader/Makefile     |  1 +
 lib/efi_loader/efi_var_sf.c | 92 +++++++++++++++++++++++++++++++++++++
 3 files changed, 126 insertions(+), 1 deletion(-)
 create mode 100644 lib/efi_loader/efi_var_sf.c

diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index 13e44be1d067..bb40cc899a13 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -123,6 +123,24 @@ config EFI_VARIABLE_FILE_STORE
 	  Select this option if you want non-volatile UEFI variables to be
 	  stored as file /ubootefi.var on the EFI system partition.
 
+config EFI_VARIABLE_SF_STORE
+	bool "Store non-volatile UEFI variables in SPI Flash"
+	depends on SPI_FLASH
+	help
+	  Select this option if you want non-volatile UEFI variables to be
+	  stored in SPI Flash.
+
+	  Define CONFIG_EFI_VARIABLE_SF_OFFSET as offset in SPI Flash to use as
+	  the storage for variables. CONFIG_EFI_VAR_BUF_SIZE defines the space
+	  needed.
+
+	  Note that SPI Flash devices have a limited number of program/erase
+	  cycles. Frequent updates to UEFI variables may cause excessive wear
+	  and can permanently damage the flash device, particularly on SPI NAND
+	  or low-end SPI NOR parts without wear leveling. This option should be
+	  used with care on such systems, and is not recommended for platforms
+	  where UEFI variables are updated frequently.
+
 config EFI_MM_COMM_TEE
 	bool "UEFI variables storage service via the trusted world"
 	depends on OPTEE
@@ -152,7 +170,7 @@ endchoice
 
 config EFI_RT_VOLATILE_STORE
 	bool "Allow variable runtime services in volatile storage (e.g RAM)"
-	depends on EFI_VARIABLE_FILE_STORE
+	depends on EFI_VARIABLE_FILE_STORE || EFI_VARIABLE_SF_STORE
 	help
 	  When EFI variables are stored on file we don't allow SetVariableRT,
 	  since the OS doesn't know how to write that file. At the same time
@@ -193,6 +211,20 @@ config FFA_SHARED_MM_BUF_ADDR
 	  the MM SP in secure world.
 	  It is assumed that the MM SP knows the address of the shared MM communication buffer.
 
+config EFI_VARIABLE_SF_OFFSET
+	hex "EFI variables in SPI flash offset"
+	depends on EFI_VARIABLE_SF_STORE
+	help
+	  Offset from the start of the SPI Flash where EFI variables will be stored.
+	  This should be aligned to the sector size of SPI Flash.
+
+config EFI_VARIABLE_SF_DEVICE_INDEX
+	int "Device Index for target SPI Flash"
+	default 0
+	help
+	  The index of SPI Flash device used for storing EFI variables. This would be
+	  needed if there are more than 1 SPI Flash devices available to use.
+
 config EFI_VARIABLES_PRESEED
 	bool "Initial values for UEFI variables"
 	depends on !COMPILE_TEST
diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
index ca1775eb03be..d73ad43951b1 100644
--- a/lib/efi_loader/Makefile
+++ b/lib/efi_loader/Makefile
@@ -54,6 +54,7 @@ obj-y += efi_variable_tee.o
 else
 obj-y += efi_variable.o
 obj-$(CONFIG_EFI_VARIABLE_FILE_STORE) += efi_var_file.o
+obj-$(CONFIG_EFI_VARIABLE_SF_STORE) += efi_var_sf.o
 obj-$(CONFIG_EFI_VARIABLES_PRESEED) += efi_var_seed.o
 endif
 obj-y += efi_watchdog.o
diff --git a/lib/efi_loader/efi_var_sf.c b/lib/efi_loader/efi_var_sf.c
new file mode 100644
index 000000000000..81810bbabb68
--- /dev/null
+++ b/lib/efi_loader/efi_var_sf.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * SPI Flash interface for UEFI variables
+ *
+ * Copyright (c) 2023, Shantur Rathore
+ * Copyright (C) 2026, Advanced Micro Devices, Inc.
+ */
+
+#define LOG_CATEGORY LOGC_EFI
+
+#include <efi_loader.h>
+#include <efi_variable.h>
+#include <spi_flash.h>
+#include <dm.h>
+
+efi_status_t efi_var_to_storage(void)
+{
+	efi_status_t ret;
+	struct efi_var_file *buf;
+	loff_t len;
+	struct udevice *sfdev;
+
+	ret = efi_var_collect(&buf, &len, EFI_VARIABLE_NON_VOLATILE);
+	if (len > EFI_VAR_BUF_SIZE) {
+		log_err("EFI var buffer length more than target SPI Flash size");
+		ret = EFI_OUT_OF_RESOURCES;
+		goto error;
+	}
+
+	log_debug("%s - Got buffer to write buf->len : %d\n", __func__, buf->length);
+
+	if (ret != EFI_SUCCESS)
+		goto error;
+
+	ret = uclass_get_device(UCLASS_SPI_FLASH, CONFIG_EFI_VARIABLE_SF_DEVICE_INDEX, &sfdev);
+	if (ret)
+		goto error;
+
+	ret = spi_flash_erase_dm(sfdev, CONFIG_EFI_VARIABLE_SF_OFFSET, EFI_VAR_BUF_SIZE);
+	log_debug("%s - Erased SPI Flash offset %x\n", __func__, CONFIG_EFI_VARIABLE_SF_OFFSET);
+	if (ret)
+		goto error;
+
+	ret = spi_flash_write_dm(sfdev, CONFIG_EFI_VARIABLE_SF_OFFSET, len, buf);
+	log_debug("%s - Wrote buffer to SPI Flash : %ld\n", __func__, ret);
+
+	if (ret)
+		goto error;
+
+	ret = EFI_SUCCESS;
+error:
+	if (ret)
+		log_err("Failed to persist EFI variables in SF\n");
+	free(buf);
+	return ret;
+}
+
+efi_status_t efi_var_from(void)
+{
+	struct efi_var_file *buf;
+	efi_status_t ret;
+	struct udevice *sfdev;
+
+	buf = calloc(1, EFI_VAR_BUF_SIZE);
+	if (!buf) {
+		log_err("%s - Unable to allocate buffer\n", __func__);
+		return EFI_OUT_OF_RESOURCES;
+	}
+
+	ret = uclass_get_device(UCLASS_SPI_FLASH, 0, &sfdev);
+	if (ret)
+		goto error;
+
+	ret = spi_flash_read_dm(sfdev, CONFIG_EFI_VARIABLE_SF_OFFSET,
+				EFI_VAR_BUF_SIZE, buf);
+
+	log_debug("%s - read buffer buf->length: %x\n", __func__, buf->length);
+
+	if (ret || buf->length < sizeof(struct efi_var_file)) {
+		log_err("%s - buffer read from SPI Flash isn't valid\n", __func__);
+		goto error;
+	}
+
+	ret = efi_var_restore(buf, false);
+	if (ret != EFI_SUCCESS)
+		log_err("%s - Unable to restore EFI variables from buffer\n", __func__);
+
+	ret = EFI_SUCCESS;
+error:
+	free(buf);
+	return ret;
+}
-- 
2.43.0

RE: [PATCH v6 2/3] efi_var: Unify read/write access helper function

[Maarten Brock]

Hello Michal,

Why are the new function names non-symmetrical?
efi_var_to_storage <-> efi_var_from ...

Maarten
> -----Original Message-----
> From: U-Boot <u-boot-bounces@lists.denx.de> On Behalf Of Michal Simek
> Sent: Tuesday 3 February 2026 8:58
> To: u-boot@lists.denx.de; git@amd.com
> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>; Heinrich Schuchardt
> <xypron.glpk@gmx.de>; Shantur Rathore <i@shantur.com>; Tom Rini
> <trini@konsulko.com>
> Subject: [PATCH v6 2/3] efi_var: Unify read/write access helper function
> 
> efi_var_to/from_file() suggest method where variables are placed. But there
> is no reason for it and generic name can be used to wire also different
> locations for variables.
> 
> Signed-off-by: Michal Simek <michal.simek@amd.com>
> Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
> ---
> 
> Changes in v6:
> - sed -i 's/efi_var_read/efi_var_from/g'
> - sed -i 's/efi_var_write/efi_var_to_storage/g'
> 
> Changes in v4:
> - New patch based on review comments from v3
> 
>  include/efi_variable.h        | 13 ++++---------
>  lib/efi_loader/efi_var_file.c |  8 ++++----
>  lib/efi_loader/efi_variable.c |  4 ++--
>  3 files changed, 10 insertions(+), 15 deletions(-)
> 
> diff --git a/include/efi_variable.h b/include/efi_variable.h
> index ee68fa4a885f..2b06505b8654 100644
> --- a/include/efi_variable.h
> +++ b/include/efi_variable.h
> @@ -137,13 +137,11 @@ struct efi_var_file {
>  };
> 
>  /**
> - * efi_var_to_file() - save non-volatile variables as file
> - *
> - * File ubootefi.var is created on the EFI system partion.
> + * efi_var_to_storage() - save non-volatile variables
>   *
>   * Return:	status code
>   */
> -efi_status_t efi_var_to_file(void);
> +efi_status_t efi_var_to_storage(void);
> 
>  /**
>   * efi_var_collect() - collect variables in buffer
> @@ -178,17 +176,14 @@ efi_status_t __maybe_unused
> efi_var_collect(struct efi_var_file **bufp, loff_t *
>  efi_status_t efi_var_restore(struct efi_var_file *buf, bool safe);
> 
>  /**
> - * efi_var_from_file() - read variables from file
> - *
> - * File ubootefi.var is read from the EFI system partitions and the variables
> - * stored in the file are created.
> + * efi_var_from() - read variables
>   *
>   * In case the file does not exist yet or a variable cannot be set EFI_SUCCESS
>   * is returned.
>   *
>   * Return:	status code
>   */
> -efi_status_t efi_var_from_file(void);
> +efi_status_t efi_var_from(void);
> 
>  /**
>   * efi_var_mem_init() - set-up variable list
> diff --git a/lib/efi_loader/efi_var_file.c b/lib/efi_loader/efi_var_file.c
> index d32edaac277d..d012d6a18b02 100644
> --- a/lib/efi_loader/efi_var_file.c
> +++ b/lib/efi_loader/efi_var_file.c
> @@ -43,13 +43,13 @@ static efi_status_t __maybe_unused
> efi_set_blk_dev_to_system_partition(void)
>  }
> 
>  /**
> - * efi_var_to_file() - save non-volatile variables as file
> + * efi_var_to_storage() - save non-volatile variables as file
>   *
>   * File ubootefi.var is created on the EFI system partion.
>   *
>   * Return:	status code
>   */
> -efi_status_t efi_var_to_file(void)
> +efi_status_t efi_var_to_storage(void)
>  {
>  	efi_status_t ret;
>  	struct efi_var_file *buf;
> @@ -85,7 +85,7 @@ out:
>  }
> 
>  /**
> - * efi_var_from_file() - read variables from file
> + * efi_var_from() - read variables from file
>   *
>   * File ubootefi.var is read from the EFI system partitions and the variables
>   * stored in the file are created.
> @@ -98,7 +98,7 @@ out:
>   *
>   * Return:	status code
>   */
> -efi_status_t efi_var_from_file(void)
> +efi_status_t efi_var_from(void)
>  {
>  	struct efi_var_file *buf;
>  	loff_t len;
> diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
> index 6e45134c61bf..42f3ba901556 100644
> --- a/lib/efi_loader/efi_variable.c
> +++ b/lib/efi_loader/efi_variable.c
> @@ -404,7 +404,7 @@ efi_status_t efi_set_variable_int(const u16
> *variable_name,
>  		if (IS_ENABLED(CONFIG_EFI_VARIABLE_NO_STORE))
>  			return EFI_SUCCESS;
> 
> -		efi_var_to_file();
> +		efi_var_to_storage();
>  	}
> 
>  	return EFI_SUCCESS;
> @@ -599,7 +599,7 @@ efi_status_t efi_init_variables(void)
>  		return ret;
> 
>  	if (!IS_ENABLED(CONFIG_EFI_VARIABLE_NO_STORE)) {
> -		ret = efi_var_from_file();
> +		ret = efi_var_from();
>  		if (ret != EFI_SUCCESS)
>  			return ret;
>  	}
> --
> 2.43.0

Re: [PATCH v6 2/3] efi_var: Unify read/write access helper function

[Michal Simek]

Hi,

On 2/3/26 10:44, Maarten Brock wrote:
> Hello Michal,
> 
> Why are the new function names non-symmetrical?
> efi_var_to_storage <-> efi_var_from ...

Ilias was asking about these names in v5 review.

Thanks,
Michal

RE: [PATCH v6 2/3] efi_var: Unify read/write access helper function

[Maarten Brock]

> -----Original Message-----
> From: Michal Simek <michal.simek@amd.com>
> Sent: Tuesday 3 February 2026 11:10
> To: Maarten Brock <Maarten.Brock@sttls.nl>; u-boot@lists.denx.de;
> git@amd.com
> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>; Heinrich Schuchardt
> <xypron.glpk@gmx.de>; Shantur Rathore <i@shantur.com>; Tom Rini
> <trini@konsulko.com>
> Subject: Re: [PATCH v6 2/3] efi_var: Unify read/write access helper function
> 
> Hi,
> 
> On 2/3/26 10:44, Maarten Brock wrote:
> > Hello Michal,
> >
> > Why are the new function names non-symmetrical?
> > efi_var_to_storage <-> efi_var_from ...
> 
> Ilias was asking about these names in v5 review.

I'm sure he meant something different from what you implemented.

> I am ok with this with a small nit.
> Can we rename efi_var_read/write to efi_var_from/to_storage? I want to
> make it clealer what these functions are used for
> 
> With the changes above
> Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

I think Ilias meant to use:
efi_var_from_storage & efi_var_to_storage
and not:
efi_var_from         & efi_var_to_storage

> 
> Thanks,
> Michal

Kind regards,
Maarten

Re: [PATCH v6 2/3] efi_var: Unify read/write access helper function

[Michal Simek]

On 2/3/26 12:29, Maarten Brock wrote:
>> -----Original Message-----
>> From: Michal Simek <michal.simek@amd.com>
>> Sent: Tuesday 3 February 2026 11:10
>> To: Maarten Brock <Maarten.Brock@sttls.nl>; u-boot@lists.denx.de;
>> git@amd.com
>> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>; Heinrich Schuchardt
>> <xypron.glpk@gmx.de>; Shantur Rathore <i@shantur.com>; Tom Rini
>> <trini@konsulko.com>
>> Subject: Re: [PATCH v6 2/3] efi_var: Unify read/write access helper function
>>
>> Hi,
>>
>> On 2/3/26 10:44, Maarten Brock wrote:
>>> Hello Michal,
>>>
>>> Why are the new function names non-symmetrical?
>>> efi_var_to_storage <-> efi_var_from ...
>>
>> Ilias was asking about these names in v5 review.
> 
> I'm sure he meant something different from what you implemented.
> 
>> I am ok with this with a small nit.
>> Can we rename efi_var_read/write to efi_var_from/to_storage? I want to
>> make it clealer what these functions are used for
>>
>> With the changes above
>> Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
> 
> I think Ilias meant to use:
> efi_var_from_storage & efi_var_to_storage
> and not:
> efi_var_from         & efi_var_to_storage

You are likely right. Let me fix that.

Thanks,
Michal

Re: [PATCH v6 2/3] efi_var: Unify read/write access helper function

[Ilias Apalodimas]

On Tue, 3 Feb 2026 at 13:29, Maarten Brock <Maarten.Brock@sttls.nl> wrote:
>
> > -----Original Message-----
> > From: Michal Simek <michal.simek@amd.com>
> > Sent: Tuesday 3 February 2026 11:10
> > To: Maarten Brock <Maarten.Brock@sttls.nl>; u-boot@lists.denx.de;
> > git@amd.com
> > Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>; Heinrich Schuchardt
> > <xypron.glpk@gmx.de>; Shantur Rathore <i@shantur.com>; Tom Rini
> > <trini@konsulko.com>
> > Subject: Re: [PATCH v6 2/3] efi_var: Unify read/write access helper function
> >
> > Hi,
> >
> > On 2/3/26 10:44, Maarten Brock wrote:
> > > Hello Michal,
> > >
> > > Why are the new function names non-symmetrical?
> > > efi_var_to_storage <-> efi_var_from ...
> >
> > Ilias was asking about these names in v5 review.
>
> I'm sure he meant something different from what you implemented.
>
> > I am ok with this with a small nit.
> > Can we rename efi_var_read/write to efi_var_from/to_storage? I want to
> > make it clealer what these functions are used for
> >
> > With the changes above
> > Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
>
> I think Ilias meant to use:
> efi_var_from_storage & efi_var_to_storage

Yes , thanks for claryfying this

/Ilias
> and not:
> efi_var_from         & efi_var_to_storage
>
> >
> > Thanks,
> > Michal
>
> Kind regards,
> Maarten

Re: [PATCH v6 2/3] efi_var: Unify read/write access helper function

[Michal Simek]

On 2/4/26 13:07, Ilias Apalodimas wrote:
> On Tue, 3 Feb 2026 at 13:29, Maarten Brock <Maarten.Brock@sttls.nl> wrote:
>>
>>> -----Original Message-----
>>> From: Michal Simek <michal.simek@amd.com>
>>> Sent: Tuesday 3 February 2026 11:10
>>> To: Maarten Brock <Maarten.Brock@sttls.nl>; u-boot@lists.denx.de;
>>> git@amd.com
>>> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>; Heinrich Schuchardt
>>> <xypron.glpk@gmx.de>; Shantur Rathore <i@shantur.com>; Tom Rini
>>> <trini@konsulko.com>
>>> Subject: Re: [PATCH v6 2/3] efi_var: Unify read/write access helper function
>>>
>>> Hi,
>>>
>>> On 2/3/26 10:44, Maarten Brock wrote:
>>>> Hello Michal,
>>>>
>>>> Why are the new function names non-symmetrical?
>>>> efi_var_to_storage <-> efi_var_from ...
>>>
>>> Ilias was asking about these names in v5 review.
>>
>> I'm sure he meant something different from what you implemented.
>>
>>> I am ok with this with a small nit.
>>> Can we rename efi_var_read/write to efi_var_from/to_storage? I want to
>>> make it clealer what these functions are used for
>>>
>>> With the changes above
>>> Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
>>
>> I think Ilias meant to use:
>> efi_var_from_storage & efi_var_to_storage
> 
> Yes , thanks for claryfying this

Take a look at v7.

M