bootstd: usb: Add a bootdev driver

Add a bootdev driver for USB host. It can use the distro boot mechanism to
locate a file, or any other available bootmeth.

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

common/usb_storage.c

@@ -34,6 +34,7 @@
 
 #include <common.h>
 #include <blk.h>
+#include <bootdev.h>
 #include <command.h>
 #include <dm.h>
 #include <errno.h>
@@ -243,6 +244,16 @@ static int usb_stor_probe_device(struct usb_device *udev)
 		ret = blk_probe_or_unbind(dev);
 		if (ret)
 			return ret;
+
+		ret = bootdev_setup_sibling_blk(dev, "usb_bootdev");
+		if (ret) {
+			int ret2;
+
+			ret2 = device_unbind(dev);
+			if (ret2)
+				return log_msg_ret("bootdev", ret2);
+			return log_msg_ret("bootdev", ret);
+		}
 	}
 #else
 	/* We don't have space to even probe if we hit the maximum */

drivers/usb/host/Makefile

@@ -8,6 +8,10 @@ obj-y += usb-uclass.o
 obj-$(CONFIG_SANDBOX) += usb-sandbox.o
 endif
 
+ifdef CONFIG_$(SPL_TPL_)USB_STORAGE
+obj-$(CONFIG_$(SPL_TPL_)BOOTSTD) += usb_bootdev.o
+endif
+
 # ohci
 obj-$(CONFIG_USB_OHCI_NEW) += ohci-hcd.o
 obj-$(CONFIG_USB_ATMEL) += ohci-at91.o

drivers/usb/host/usb_bootdev.c

@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Bootdevice for USB
+ *
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#include <common.h>
+#include <bootdev.h>
+#include <dm.h>
+#include <usb.h>
+
+static int usb_get_bootflow(struct udevice *dev, struct bootflow_iter *iter,
+			    struct bootflow *bflow)
+{
+	struct udevice *blk;
+	int ret;
+
+	ret = bootdev_get_sibling_blk(dev, &blk);
+	/*
+	 * If there is no media, indicate that no more partitions should be
+	 * checked
+	 */
+	if (ret == -EOPNOTSUPP)
+		ret = -ESHUTDOWN;
+	if (ret)
+		return log_msg_ret("blk", ret);
+	assert(blk);
+	ret = bootdev_find_in_blk(dev, blk, iter, bflow);
+	if (ret)
+		return log_msg_ret("find", ret);
+
+	return 0;
+}
+
+static int usb_bootdev_bind(struct udevice *dev)
+{
+	struct bootdev_uc_plat *ucp = dev_get_uclass_plat(dev);
+
+	ucp->prio = BOOTDEVP_3_SCAN_SLOW;
+
+	return 0;
+}
+
+struct bootdev_ops usb_bootdev_ops = {
+	.get_bootflow	= usb_get_bootflow,
+};
+
+static const struct udevice_id usb_bootdev_ids[] = {
+	{ .compatible = "u-boot,bootdev-usb" },
+	{ }
+};
+
+U_BOOT_DRIVER(usb_bootdev) = {
+	.name		= "usb_bootdev",
+	.id		= UCLASS_BOOTDEV,
+	.ops		= &usb_bootdev_ops,
+	.bind		= usb_bootdev_bind,
+	.of_match	= usb_bootdev_ids,
+};