Merge branch '2022-04-25-initial-implementation-of-stdboot'

To quote the author:
The bootflow feature provide a built-in way for U-Boot to automatically
boot an Operating System without custom scripting and other customisation.
This is called 'standard boot' since it provides a standard way for
U-Boot to boot a distro, without scripting.

It introduces the following concepts:

   - bootdev - a device which can hold a distro
   - bootmeth - a method to scan a bootdev to find bootflows (owned by
                U-Boot)
   - bootflow - a description of how to boot (owned by the distro)

This series provides an implementation of these, enabled to scan for
bootflows from MMC, USB and Ethernet. It supports the existing distro
boot as well as the EFI loader flow (bootefi/bootmgr). It works
similiarly to the existing script-based approach, but is native to
U-Boot.

With this we can boot on a Raspberry Pi 3 with just one command:

   bootflow scan -lb

which means to scan, listing (-l) each bootflow and trying to boot each
one (-b). The final patch shows this.

With a standard way to identify boot devices, booting become easier. It
also should be possible to support U-Boot scripts, for backwards
compatibility only.

...

The design is described in these two documents:

https://drive.google.com/file/d/1ggW0KJpUOR__vBkj3l61L2dav4ZkNC12/view?usp=sharing

https://drive.google.com/file/d/1kTrflO9vvGlKp-ZH_jlgb9TY3WYG6FF9/view?usp=sharing

1 files changed, 183 insertions, 0 deletions

diff --git a/boot/bootstd-uclass.c b/boot/bootstd-uclass.c
new file mode 100644
index 00000000000..3c6c32ae604
--- /dev/null
+++ b/boot/bootstd-uclass.c
@@ -0,0 +1,183 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Uclass implementation for standard boot
+ *
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <[email protected]>
+ */
+
+#include <common.h>
+#include <bootflow.h>
+#include <bootstd.h>
+#include <dm.h>
+#include <log.h>
+#include <malloc.h>
+#include <dm/device-internal.h>
+#include <dm/lists.h>
+#include <dm/read.h>
+#include <dm/uclass-internal.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/* These are used if filename-prefixes is not present */
+const char *const default_prefixes[] = {"/", "/boot/", NULL};
+
+static int bootstd_of_to_plat(struct udevice *dev)
+{
+	struct bootstd_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	if (IS_ENABLED(CONFIG_BOOTSTD_FULL)) {
+		/* Don't check errors since livetree and flattree are different */
+		ret = dev_read_string_list(dev, "filename-prefixes",
+					   &priv->prefixes);
+		dev_read_string_list(dev, "bootdev-order",
+				     &priv->bootdev_order);
+	}
+
+	return 0;
+}
+
+static void bootstd_clear_glob_(struct bootstd_priv *priv)
+{
+	while (!list_empty(&priv->glob_head)) {
+		struct bootflow *bflow;
+
+		bflow = list_first_entry(&priv->glob_head, struct bootflow,
+					 glob_node);
+		bootflow_remove(bflow);
+	}
+}
+
+void bootstd_clear_glob(void)
+{
+	struct bootstd_priv *std;
+
+	if (bootstd_get_priv(&std))
+		return;
+
+	bootstd_clear_glob_(std);
+}
+
+static int bootstd_remove(struct udevice *dev)
+{
+	struct bootstd_priv *priv = dev_get_priv(dev);
+
+	free(priv->prefixes);
+	free(priv->bootdev_order);
+	bootstd_clear_glob_(priv);
+
+	return 0;
+}
+
+const char *const *const bootstd_get_bootdev_order(struct udevice *dev)
+{
+	struct bootstd_priv *std = dev_get_priv(dev);
+
+	return std->bootdev_order;
+}
+
+const char *const *const bootstd_get_prefixes(struct udevice *dev)
+{
+	struct bootstd_priv *std = dev_get_priv(dev);
+
+	return std->prefixes ? std->prefixes : default_prefixes;
+}
+
+int bootstd_get_priv(struct bootstd_priv **stdp)
+{
+	struct udevice *dev;
+	int ret;
+
+	ret = uclass_first_device_err(UCLASS_BOOTSTD, &dev);
+	if (ret)
+		return ret;
+	*stdp = dev_get_priv(dev);
+
+	return 0;
+}
+
+static int bootstd_probe(struct udevice *dev)
+{
+	struct bootstd_priv *std = dev_get_priv(dev);
+
+	INIT_LIST_HEAD(&std->glob_head);
+
+	return 0;
+}
+
+/* For now, bind the boormethod device if none are found in the devicetree */
+int dm_scan_other(bool pre_reloc_only)
+{
+	struct driver *drv = ll_entry_start(struct driver, driver);
+	const int n_ents = ll_entry_count(struct driver, driver);
+	struct udevice *dev, *bootstd;
+	int i, ret;
+
+	/* These are not needed before relocation */
+	if (!(gd->flags & GD_FLG_RELOC))
+		return 0;
+
+	/* Create a bootstd device if needed */
+	uclass_find_first_device(UCLASS_BOOTSTD, &bootstd);
+	if (!bootstd) {
+		ret = device_bind_driver(gd->dm_root, "bootstd_drv", "bootstd",
+					 &bootstd);
+		if (ret)
+			return log_msg_ret("bootstd", ret);
+	}
+
+	/* If there are no bootmeth devices, create them */
+	uclass_find_first_device(UCLASS_BOOTMETH, &dev);
+	if (dev)
+		return 0;
+
+	for (i = 0; i < n_ents; i++, drv++) {
+		/*
+		 * Disable EFI Manager for now as no one uses it so it is
+		 * confusing
+		 */
+		if (drv->id == UCLASS_BOOTMETH &&
+		    strcmp("efi_mgr_bootmeth", drv->name)) {
+			const char *name = drv->name;
+
+			if (!strncmp("bootmeth_", name, 9))
+				name += 9;
+			ret = device_bind(bootstd, drv, name, 0, ofnode_null(),
+					  &dev);
+			if (ret)
+				return log_msg_ret("meth", ret);
+		}
+	}
+
+	/* 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;
+}
+
+static const struct udevice_id bootstd_ids[] = {
+	{ .compatible = "u-boot,boot-std" },
+	{ }
+};
+
+U_BOOT_DRIVER(bootstd_drv) = {
+	.id		= UCLASS_BOOTSTD,
+	.name		= "bootstd_drv",
+	.of_to_plat	= bootstd_of_to_plat,
+	.probe		= bootstd_probe,
+	.remove		= bootstd_remove,
+	.of_match	= bootstd_ids,
+	.priv_auto	= sizeof(struct bootstd_priv),
+};
+
+UCLASS_DRIVER(bootstd) = {
+	.id		= UCLASS_BOOTSTD,
+	.name		= "bootstd",
+#if CONFIG_IS_ENABLED(OF_REAL)
+	.post_bind	= dm_scan_fdt_dev,
+#endif
+};