[PATCH] efi_loader: Disable devices before handing over control

[Ilias Apalodimas]

U-Boot Driver Model is supposed to remove devices with either
DM_REMOVE_ACTIVE_DMA or DM_REMOVE_OS_PREPARE flags set, before exiting.
Our bootm command does that by explicitly calling calling
"dm_remove_devices_flags(DM_REMOVE_ACTIVE_ALL);" and we also disable any
USB devices.

The EFI equivalent is doing none of those at the moment. As a result
probing an fTPM driver now renders it unusable in Linux. During our
(*probe) callback we open a session with OP-TEE, which is supposed to
close with our (*remove) callback. Since the (*remove) is never called,
once we boot into Linux and try to probe the device again we are getting
a busy error response. We also never free

So let's fix this by mimicking what bootm does and disconnect devices
when efi_exit_boot_services() is called. Note that for the OP-TEE case
and in particular any subsequent bootloader that wants to use a device
(e.g GRUB) will need to call exit_boot_services() in order to close the
session.

Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
---
 lib/efi_loader/efi_boottime.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index bf78176217c6..25e6cf0fe719 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -18,6 +18,8 @@
 #include <pe.h>
 #include <u-boot/crc.h>
 #include <watchdog.h>
+#include <dm/device.h>
+#include <dm/root.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -1994,7 +1996,10 @@ static efi_status_t EFIAPI efi_exit_boot_services(efi_handle_t image_handle,
 			list_del(&evt->link);
 	}
 
+	if IS_ENABLED(CONFIG_USB_DEVICE)
+		udc_disconnect();
 	board_quiesce_devices();
+	dm_remove_devices_flags(DM_REMOVE_ACTIVE_ALL);
 
 	/* Patch out unsupported runtime function */
 	efi_runtime_detach();
-- 
2.28.0