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

4 files changed, 23 insertions, 4 deletions

diff --git a/include/dm/device.h b/include/dm/device.h
index e0f86f5df9f..b474888d025 100644
--- a/include/dm/device.h
+++ b/include/dm/device.h
@@ -799,7 +799,7 @@ int device_find_first_child_by_uclass(const struct udevice *parent,
 				      struct udevice **devp);
 
 /**
- * device_find_child_by_name() - Find a child by device name
+ * device_find_child_by_namelen() - Find a child by device name
  *
  * @parent:	Parent device to search
  * @name:	Name to look for
diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
index 230b1ea528c..3ba69ad9a08 100644
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -38,6 +38,9 @@ enum uclass_id {
 	UCLASS_AXI,		/* AXI bus */
 	UCLASS_BLK,		/* Block device */
 	UCLASS_BOOTCOUNT,       /* Bootcount backing store */
+	UCLASS_BOOTDEV,		/* Boot device for locating an OS to boot */
+	UCLASS_BOOTMETH,	/* Bootmethod for booting an OS */
+	UCLASS_BOOTSTD,		/* Standard boot driver */
 	UCLASS_BUTTON,		/* Button */
 	UCLASS_CACHE,		/* Cache controller */
 	UCLASS_CLK,		/* Clock source, e.g. used by peripherals */
diff --git a/include/dm/uclass-internal.h b/include/dm/uclass-internal.h
index daf856c03cf..3ddcdd21439 100644
--- a/include/dm/uclass-internal.h
+++ b/include/dm/uclass-internal.h
@@ -155,6 +155,22 @@ int uclass_find_first_device(enum uclass_id id, struct udevice **devp);
 int uclass_find_next_device(struct udevice **devp);
 
 /**
+ * uclass_find_device_by_namelen() - Find uclass device based on ID and name
+ *
+ * This searches for a device with the exactly given name.
+ *
+ * The device is NOT probed, it is merely returned.
+ *
+ * @id: ID to look up
+ * @name: name of a device to find
+ * @len: Length of @name (the uclass driver name must have the same length)
+ * @devp: Returns pointer to device (the first one with the name)
+ * Return: 0 if OK, -ve on error
+ */
+int uclass_find_device_by_namelen(enum uclass_id id, const char *name, int len,
+				  struct udevice **devp);
+
+/**
  * uclass_find_device_by_name() - Find uclass device based on ID and name
  *
  * This searches for a device with the exactly given name.
diff --git a/include/dm/uclass.h b/include/dm/uclass.h
index aafe6522886..f6c0110b061 100644
--- a/include/dm/uclass.h
+++ b/include/dm/uclass.h
@@ -173,13 +173,13 @@ int uclass_get(enum uclass_id key, struct uclass **ucp);
 const char *uclass_get_name(enum uclass_id id);
 
 /**
- * uclass_get_by_name_len() - Look up a uclass by its partial driver name
+ * uclass_get_by_namelen() - Look up a uclass by its driver name
  *
  * @name: Name to look up
- * @len: Length of the partial name
+ * @len: Length of @name (the uclass driver name must have the same length)
  * Return: the associated uclass ID, or UCLASS_INVALID if not found
  */
-enum uclass_id uclass_get_by_name_len(const char *name, int len);
+enum uclass_id uclass_get_by_namelen(const char *name, int len);
 
 /**
  * uclass_get_by_name() - Look up a uclass by its driver name