sunxi: Add a bootmeth for FEL

Add support for booting from a script loaded over FEL. This mirrors the
bootcmd_fel provided by distro boot.

Series-changes: 2
- Put the FEL bootmeth before all other global bootmeths

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>

boot/Kconfig

@@ -585,6 +585,20 @@ config BOOTMETH_EFI_BOOTMGR
 	  the EFI binary to be launched is determined. To set the EFI variables
 	  use the eficonfig command.
 
+config BOOTMETH_FEL
+	bool "Bootdev support for Sunxi FEL"
+	depends on ARCH_SUNXI
+	default y
+	help
+	  Enables support for booting over USB on a Sunxi device. This uses
+	  the FEL protocol and obtains the script address from the
+	  'fel_scriptaddr' environment variable.
+
+	  This method is only available if booting from FEL, i.e. the
+	  'fel_booted' environment variable is set.
+
+	  See https://linux-sunxi.org/FEL/Protocol for more information.
+
 config BOOTMETH_QFW
 	bool "Boot method using QEMU parameters"
 	depends on QFW

boot/Makefile

@@ -30,6 +30,7 @@ obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_EXTLINUX) += bootmeth_extlinux.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_EXTLINUX_PXE) += bootmeth_pxe.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_EFILOADER) += bootmeth_efi.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_CROS) += bootm.o bootm_os.o bootmeth_cros.o
+obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_FEL) += bootmeth_fel.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_QFW) += bootmeth_qfw.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_SANDBOX) += bootmeth_sandbox.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_SCRIPT) += bootmeth_script.o

boot/bootmeth_fel.c

@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Bootmethod for sunxi FEL loading
+ *
+ * Copyright 2024 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#define LOG_CATEGORY UCLASS_BOOTSTD
+
+#include <bootdev.h>
+#include <bootflow.h>
+#include <bootmeth.h>
+#include <command.h>
+#include <dm.h>
+#include <env.h>
+
+static int fel_check(struct udevice *dev, struct bootflow_iter *iter)
+{
+	return 0;
+}
+
+static int fel_read_bootflow(struct udevice *dev, struct bootflow *bflow)
+{
+	if (!env_get("fel_booted") || !env_get("fel_scriptaddr"))
+		return -ENOENT;
+
+	bflow->state = BOOTFLOWST_READY;
+
+	return 0;
+}
+
+static int fel_read_file(struct udevice *dev, struct bootflow *bflow,
+			 const char *file_path, ulong addr, ulong *sizep)
+{
+	return -ENOSYS;
+}
+
+static int fel_boot(struct udevice *dev, struct bootflow *bflow)
+{
+	ulong addr;
+	int ret;
+
+	addr = env_get_hex("fel_scriptaddr", 0);
+	ret = cmd_source_script(addr, NULL, NULL);
+	if (ret)
+		return log_msg_ret("boot", ret);
+
+	return 0;
+}
+
+static int fel_bootmeth_bind(struct udevice *dev)
+{
+	struct bootmeth_uc_plat *plat = dev_get_uclass_plat(dev);
+
+	plat->desc = IS_ENABLED(CONFIG_BOOTSTD_FULL) ?
+	   "Sunxi FEL boot over USB" : "FEL";
+	plat->flags = BOOTMETHF_GLOBAL;
+
+	return 0;
+}
+
+static struct bootmeth_ops fel_bootmeth_ops = {
+	.check		= fel_check,
+	.read_bootflow	= fel_read_bootflow,
+	.read_file	= fel_read_file,
+	.boot		= fel_boot,
+};
+
+static const struct udevice_id fel_bootmeth_ids[] = {
+	{ .compatible = "u-boot,fel-bootmeth" },
+	{ }
+};
+
+U_BOOT_DRIVER(bootmeth_2fel) = {
+	.name		= "bootmeth_fel",
+	.id		= UCLASS_BOOTMETH,
+	.of_match	= fel_bootmeth_ids,
+	.ops		= &fel_bootmeth_ops,
+	.bind		= fel_bootmeth_bind,
+};