bootstd: Add a system bootdev for strange boot methods

Some boot methods don't act on a single bootdev but instead do their own
thing. An example is EFI bootmgr which scan various devices using its own
logic. Add a bootdev to handle this.

Signed-off-by: Simon Glass <sjg@chromium.org>

boot/Makefile

@@ -19,7 +19,7 @@ obj-y += image.o image-board.o
 obj-$(CONFIG_ANDROID_AB) += android_ab.o
 obj-$(CONFIG_ANDROID_BOOT_IMAGE) += image-android.o image-android-dt.o
 
-obj-$(CONFIG_$(SPL_TPL_)BOOTSTD) += bootdev-uclass.o
+obj-$(CONFIG_$(SPL_TPL_)BOOTSTD) += bootdev-uclass.o system_bootdev.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTSTD) += bootflow.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTSTD) += bootmeth-uclass.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTSTD) += bootstd-uclass.o

boot/bootstd-uclass.c

@@ -150,6 +150,12 @@ int dm_scan_other(bool pre_reloc_only)
 		}
 	}
 
+	/* Create the system bootdev too */
+	ret = device_bind_driver(bootstd, "system_bootdev", "system-bootdev",
+				 &dev);
+	if (ret)
+		return log_msg_ret("sys", ret);
+
 	return 0;
 }
 

boot/system_bootdev.c

@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Bootdevice for system, used for bootmeths not tied to any partition device
+ *
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#define LOG_CATEGORY UCLASS_BOOTSTD
+
+#include <common.h>
+#include <bootdev.h>
+#include <bootflow.h>
+#include <bootmeth.h>
+#include <command.h>
+#include <distro.h>
+#include <dm.h>
+#include <log.h>
+#include <net.h>
+
+static int system_get_bootflow(struct udevice *dev, struct bootflow_iter *iter,
+			       struct bootflow *bflow)
+{
+	int ret;
+
+	/* Must be an bootstd device */
+	ret = bootflow_iter_uses_system(iter);
+	if (ret)
+		return log_msg_ret("net", ret);
+
+	ret = bootmeth_check(bflow->method, iter);
+	if (ret)
+		return log_msg_ret("check", ret);
+
+	ret = bootmeth_read_bootflow(bflow->method, bflow);
+	if (ret)
+		return log_msg_ret("method", ret);
+
+	return 0;
+}
+
+static int system_bootdev_bind(struct udevice *dev)
+{
+	struct bootdev_uc_plat *ucp = dev_get_uclass_plat(dev);
+
+	ucp->prio = BOOTDEVP_6_SYSTEM;
+
+	return 0;
+}
+
+struct bootdev_ops system_bootdev_ops = {
+	.get_bootflow	= system_get_bootflow,
+};
+
+static const struct udevice_id system_bootdev_ids[] = {
+	{ .compatible = "u-boot,bootdev-system" },
+	{ }
+};
+
+U_BOOT_DRIVER(system_bootdev) = {
+	.name		= "system_bootdev",
+	.id		= UCLASS_BOOTDEV,
+	.ops		= &system_bootdev_ops,
+	.bind		= system_bootdev_bind,
+	.of_match	= system_bootdev_ids,
+};