efi_loader: Support loading devicetree from a FIT

Where an EFI app is loaded separately from the devicetree, it is useful
to be able to read the devicetree from a FIT. This allows use of the
automatic mechanism described in the spec:

   https://fitspec.osfw.foundation/#select-a-configuration-to-boot

For now there is no test for this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Series-changes: 1
- Correct behaviour when there is actually no FIT

Series-to: heinrich

cmd/bootefi.c

@@ -119,6 +119,62 @@ static int do_efi_selftest(void)
 	return ret != EFI_SUCCESS;
 }
 
+/**
+ * locate_fdt() - Figure out the FDT to use, either from an arg or FIT
+ *
+ * @arg: Argument to process
+ * @fdtp: Returns devicetree located, on success
+ * Return: 0 on success, -ve on error
+ *
+ *
+ * The argument is in one of two formats:
+ *
+ *	fit_addr
+ *	fit_addr[#<conf>[#extra-conf]]
+ *
+ * In the first case, a pointer to the given address is simply returned. In the
+ * second case, the FIT is scanned to select the correct FDT, which is then
+ * returned
+ */
+static int locate_fdt(const char *arg, void **fdtp)
+{
+	ulong addr;
+	void *buf;
+	char *ep;
+
+	addr = hextoul(arg, &ep);
+	buf = map_sysmem(addr, 0);
+	if (CONFIG_IS_ENABLED(FIT)) {
+
+		/* if it's not a valid FIT, bail out */
+		if (fit_check_format(buf, IMAGE_SIZE_INVAL)) {
+			/*
+			 * complain if it looks like the user is trying to use
+			 * a FIT
+			 */
+			if (*ep == '#')
+				return -EINVAL;
+			*fdtp = buf;
+		} else {
+			struct bootm_headers images = {};
+			ulong size;
+			char *fdt;
+			int ret;
+
+			/* read the devicetree from the FIT */
+			ret = boot_get_fdt(NULL, arg, IH_ARCH_DEFAULT, &images,
+					   &fdt, &size);
+			if (ret)
+				return ret;
+			*fdtp = fdt;
+		}
+	} else {
+		*fdtp = buf;
+	}
+
+	return 0;
+}
+
 /**
  * do_bootefi() - execute `bootefi` command
  *
@@ -142,10 +198,13 @@ static int do_bootefi(struct cmd_tbl *cmdtp, int flag, int argc,
 		return CMD_RET_USAGE;
 
 	if (argc > 2) {
-		uintptr_t fdt_addr;
+		int eret;
 
-		fdt_addr = hextoul(argv[2], NULL);
-		fdt = map_sysmem(fdt_addr, 0);
+		eret = locate_fdt(argv[2], &fdt);
+		if (eret) {
+			log_err("Cannot obtain devicetree (err %dE)\n", eret);
+			return CMD_RET_FAILURE;
+		}
 	} else {
 		fdt = EFI_FDT_USE_INTERNAL;
 	}

doc/usage/cmd/bootefi.rst

@@ -13,6 +13,7 @@ Synopsis
 ::
 
     bootefi <image_addr>[:<image_size>] [<fdt_addr>]
+    bootefi <image_addr>[:<image_size>] fit_addr[#<conf>[#extra-conf]]
     bootefi bootmgr [<fdt_addr>]
     bootefi hello [<fdt_addr>]
     bootefi selftest [<fdt_addr>]
@@ -20,19 +21,19 @@ Synopsis
 Description
 -----------
 
-The *bootefi* command is used to launch a UEFI binary which can be either of
+The *bootefi* command is used to launch a UEFI binary which can be any of
 
 * UEFI application
 * UEFI boot services driver
 * UEFI run-time services driver
 
 An operating system requires a hardware description which can either be
-presented as ACPI table (CONFIG\_GENERATE\_ACPI\_TABLE=y) or as device-tree.
-The load address of the device-tree may be provided as parameter *fdt\_addr*. If
+presented as ACPI table (CONFIG_GENERATE_ACPI_TABLE=y) or as device-tree.
+The load address of the device-tree may be provided as parameter *fdt_addr*. If
 this address is not specified, the bootefi command will try to fall back in
 sequence to:
 
-* the device-tree specified by environment variable *fdt\_addr*
+* the device-tree specified by environment variable *fdt_addr*
 * the device-tree specified by environment variable *fdtcontroladdr*
 
 The load address of the binary is specified by parameter *image_address*. A
@@ -60,6 +61,11 @@ fdt_addr
     U-Boot's internal device-tree $fdtcontroladdr as second fallback.
     When using ACPI no device-tree shall be specified.
 
+fit_addr
+    Address of a :doc:`../fit/index` and optional configuration specifiers for
+    the devicetree to use. The devicetree is loaded from the selected (or
+    default) configuration.
+
 image_size
     Size of the UEFI binary file. This argument is only needed if *image_addr*
     does not match the address of the last loaded UEFI binary. In this case
@@ -110,7 +116,7 @@ U-Boot can be compiled with UEFI unit tests. These unit tests are invoked using
 the *bootefi selftest* sub-command.
 
 Which unit test is executed is controlled by the environment variable
-*efi\_selftest*. If this variable is not set, all unit tests that are not marked
+*efi_selftest*. If this variable is not set, all unit tests that are not marked
 as 'on request' are executed.
 
 To show a list of the available unit tests the value *list* can be used
@@ -126,7 +132,7 @@ To show a list of the available unit tests the value *list* can be used
     'configuration tables'
     ...
 
-A single test is selected for execution by setting the *efi\_selftest*
+A single test is selected for execution by setting the *efi_selftest*
 environment variable to match one of the listed identifiers
 
 ::
@@ -140,10 +146,10 @@ return to the command line but require a board reset.
 Configuration
 -------------
 
-To use the *bootefi* command you must specify CONFIG\_CMD\_BOOTEFI=y.
-The *bootefi bootmgr* sub-command requries CMD\_BOOTEFI\_BOOTMGR=y.
-The *bootefi hello* sub-command requries CMD\_BOOTEFI\_HELLO=y.
-The *bootefi selftest* sub-command depends on CMD\_BOOTEFI\_SELFTEST=y.
+To use the *bootefi* command you must specify CONFIG_CMD_BOOTEFI=y.
+The *bootefi bootmgr* sub-command requries CMD_BOOTEFI_BOOTMGR=y.
+The *bootefi hello* sub-command requries CMD_BOOTEFI_HELLO=y.
+The *bootefi selftest* sub-command depends on CMD_BOOTEFI_SELFTEST=y.
 
 See also
 --------