From 2aa97029fd221c70abd285987fe1eba3895c1c97 Mon Sep 17 00:00:00 2001
From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Date: Thu, 21 Jan 2021 12:57:27 +0100
Subject: [PATCH] rpi-eeprom-update: Get bootloader configuration from DT

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 rpi-eeprom-config | 18 ++++++++++++++----
 rpi-eeprom-update | 36 ++++++++++++++++++++++++++++++++----
 2 files changed, 46 insertions(+), 8 deletions(-)

diff --git a/rpi-eeprom-config b/rpi-eeprom-config
index 7a5f632..0a6ce5e 100755
--- a/rpi-eeprom-config
+++ b/rpi-eeprom-config
@@ -138,8 +138,7 @@ def edit_config(eeprom=None):
         image = BootloaderImage(pending)
         current_config = image.get_config().decode('utf-8')
     else:
-        config_src = 'vcgencmd bootloader_config'
-        current_config = read_current_config()
+        current_config, config_src = read_current_config()
 
     create_tempdir()
     tmp_conf = os.path.join(TEMP_DIR, 'boot.conf')
@@ -160,7 +159,17 @@ def read_current_config():
     """
     Reads the configuration used by the current bootloader.
     """
-    return shell_cmd(['vcgencmd', 'bootloader_config'])
+    fw_base = "/sys/firmware/devicetree/base/"
+    nvmem_base = "/sys/bus/nvmem/devices/"
+
+    if os.path.exists(fw_base + "/aliases/blconfig"):
+        with open(fw_base + "/aliases/blconfig") as f:
+            nvmem_ofnode_path = fw_base + f.read().encode('ascii')
+            for d in os.listdir(nvmem_base):
+                if os.path.realpath(nvmem_base + d + "/of_node") in os.path.normpath(nvmem_ofnode_path):
+                    return (open(nvmem_base + d + "/nvmem").read(), "blconfig device")
+
+    return (shell_cmd(['vcgencmd', 'bootloader_config']), "vcgencmd bootloader_config")
 
 class BootloaderImage(object):
     def __init__(self, filename, output=None):
@@ -293,6 +302,7 @@ Operating modes:
    it must be run as root.
 
    The configuration file will be taken from:
+       * The blconfig reserved memory nvmem device
        * The cached bootloader configuration 'vcgencmd bootloader_config'
        * The current pending update - typically /boot/pieeprom.upd
 
@@ -336,7 +346,7 @@ images.
         else:
             image.read()
     elif args.config is None and args.eeprom is None:
-        current_config = read_current_config()
+        current_config, config_src = read_current_config()
         if args.out is not None:
             open(args.out, 'w').write(current_config)
         else:
diff --git a/rpi-eeprom-update b/rpi-eeprom-update
index a0643b8..09ccda8 100755
--- a/rpi-eeprom-update
+++ b/rpi-eeprom-update
@@ -104,6 +104,34 @@ die() {
    exit ${EXIT_FAILED}
 }
 
+getBootloaderConfig() {
+   # Prefer extracting bootloader's config from DT.
+   #
+   # In order to find the right nvmem device, we build the sysfs path of the
+   # bootloader reserved memory DT node to then match that path against all
+   # nvmem device's ofnode path.
+   #
+   # If the path isn't there, default to using vcgencmd.
+
+   local blconfig_alias="/sys/firmware/devicetree/base/aliases/blconfig"
+   local blconfig_nvmem_path=""
+
+   if [ -f "${blconfig_alias}" ]; then
+      local blconfig_ofnode_path="/sys/firmware/devicetree/base"$(strings "${blconfig_alias}")""
+      local blconfig_ofnode_link=$(find -L /sys/bus/nvmem -samefile "${blconfig_ofnode_path}" 2>/dev/null)
+
+      if [ -e "${blconfig_ofnode_link}" ]; then
+         blconfig_nvmem_path=$(dirname "${blconfig_ofnode_link}")
+      fi
+   fi
+
+   if [ -n "${blconfig_nvmem_path}" ]; then
+      cat "${blconfig_nvmem_path}"/nvmem
+   else
+      vcgencmd bootloader_config
+   fi
+}
+
 prepareImage()
 {
    [ -f "${BOOTLOADER_UPDATE_IMAGE}" ] || die "EEPROM image '${BOOTLOADER_UPDATE_IMAGE}' not found"
@@ -114,7 +142,7 @@ prepareImage()
    mkdir -p "${FIRMWARE_BACKUP_DIR}"
 
    # Backup the configuration of the currently loaded bootloader
-   vcgencmd bootloader_config > "${TMP_EEPROM_CONFIG}"
+   getBootloaderConfig > "${TMP_EEPROM_CONFIG}"
    backup="${FIRMWARE_BACKUP_DIR}/pieeprom-backup-$(date +%Y%m%d-%H%M%S).conf"
    cp -f "${TMP_EEPROM_CONFIG}" "${backup}"
 
@@ -355,8 +383,8 @@ checkDependencies() {
       FIRMWARE_IMAGE_DIR="${FIRMWARE_IMAGE_DIR}-${BOARD_INFO}"
    fi
 
-   if vcgencmd bootloader_config | grep -qi "Command not registered"; then
-      die "vcgencmd: 'bootloader_config' command not supported. Please update VC firmware and reboot."
+   if ! getBootloaderConfig > /dev/null; then
+      die "Unable to get bootloader config, please update VC firmware and reboot."
    fi
 
    if ! command -v sha256sum > /dev/null; then
@@ -800,7 +828,7 @@ done
 
 checkDependencies
 if [ "${AUTO_UPDATE_BOOTLOADER}" = 1 ] || [ "${AUTO_UPDATE_VL805}" = 1 ]; then
-   if vcgencmd bootloader_config | grep FREEZE_VERSION=1; then
+   if getBootloaderConfig | grep FREEZE_VERSION=1; then
       echo "EEPROM version is frozen. Skipping update"
       exit ${EXIT_EEPROM_FROZEN}
    else