Merge branch '2023-01-24-bootstd-allow-migration-from-distro_bootcmd-script'

To quote the author:
So far, standard boot does not replicate all the of the functionality
of the distro_bootcmd scripts. In particular it lacks some bootdevs and
some of the bootmeths are incomplete.

Also there is currently no internal mechanism to enumerate buses in order
to discover bootdevs, e.g. with USB.

This series addresses these shortcomings:

- Adds the concept of a 'bootdev hunter' to enumerate buses, etc. in an
  effort to find bootdevs of a certain priority
- Adds bootdevs for SCSI, IDE, NVMe, virtio, SPI flash
- Handles PXE and DHCP properly
- Supports reading the device tree with EFI and reading scripts from the
  network

It also tidies up label processing, so it is possible to use:

   bootflow scan mmc2

to scan just one MMC device (with BOOTSTD_FULL).

As before this implementation still relies on CONFIG_CMDLINE being
enabled, mostly for the network stack. Further work would be required to
disentangle that.

Quite a few tests are added but there are some gaps:

- SPI flash bootdev
- EFI FDT loading

Note that SATA works via SCSI (CONFIG_SCSI_AHCI) and does not use
driver model. Only pogo_v4 seems to be affected. Probably all thats is
needed is to call bootdev_setup_sibling_blk() in the Marvell SATA driver.

Also, while it would be possible to init MMC in a bootdev hunter, there is
no point since U-Boot always inits MMC on startup, if present.

With this series it should be possible to migrate boards to standard boot
by removing the inclusion of config_distro_bootcmd.h and instead adding
a suitable value for boot_targets to the environment, e.g.:

   boot_targets=mmc1 mmc0 nvme scsi usb pxe dhcp spi

Thus it is possible to boot automatically without scripts and boards can
use a text-based environment instead of the config.h files.

To demonstrate this, rockpro64-rk3399 is migrated to standard boot in this
series. Full migration could probably be automated using a script, similar
in concept to moveconfig:

   - obtain the board environment via 'make u-boot-initial-env'
   - get the value of "boot_targets"
   - drop config_distro_bootcmd.h from the config.h file
   - rebuild again to get the environment without distro scripts
   - write the environment (adding boot_targets) to board.env
   - remove CONFIG_EXTRA_ENV_SETTINGS from the config.h file

1 files changed, 14 insertions, 3 deletions

diff --git a/include/bootstd.h b/include/bootstd.h
index 4fa0d531001..dddb3e15384 100644
--- a/include/bootstd.h
+++ b/include/bootstd.h
@@ -22,7 +22,10 @@ struct udevice;
  * @prefixes: NULL-terminated list of prefixes to use for bootflow filenames,
  *	e.g. "/", "/boot/"; NULL if none
  * @bootdev_order: Order to use for bootdevs (or NULL if none), with each item
- *	being a bootdev label, e.g. "mmc2", "mmc1";
+ *	being a bootdev label, e.g. "mmc2", "mmc1" (NULL terminated)
+ * @env_order: Order as specified by the boot_targets env var (or NULL if none),
+ *	with each item being a bootdev label, e.g. "mmc2", "mmc1" (NULL
+ *	terminated)
  * @cur_bootdev: Currently selected bootdev (for commands)
  * @cur_bootflow: Currently selected bootflow (for commands)
  * @glob_head: Head for the global list of all bootflows across all bootdevs
@@ -30,10 +33,13 @@ struct udevice;
  * @bootmeth_order: List of bootmeth devices to use, in order, NULL-terminated
  * @vbe_bootmeth: Currently selected VBE bootmeth, NULL if none
  * @theme: Node containing the theme information
+ * @hunters_used: Bitmask of used hunters, indexed by their position in the
+ * linker list. The bit is set if the hunter has been used already
  */
 struct bootstd_priv {
 	const char **prefixes;
 	const char **bootdev_order;
+	const char **env_order;
 	struct udevice *cur_bootdev;
 	struct bootflow *cur_bootflow;
 	struct list_head glob_head;
@@ -41,6 +47,7 @@ struct bootstd_priv {
 	struct udevice **bootmeth_order;
 	struct udevice *vbe_bootmeth;
 	ofnode theme;
+	uint hunters_used;
 };
 
 /**
@@ -51,9 +58,13 @@ struct bootstd_priv {
  * The list is alloced by the bootstd driver so should not be freed. That is the
  * reason for all the const stuff in the function signature
  *
- * Return: list of string points, terminated by NULL; or NULL if no boot order
+ * @dev: bootstd device
+ * @okp: returns true if OK, false if out of memory
+ * Return: list of string pointers, terminated by NULL; or NULL if no boot
+ * order. Note that this returns NULL in the case of an empty list
  */
-const char *const *const bootstd_get_bootdev_order(struct udevice *dev);
+const char *const *const bootstd_get_bootdev_order(struct udevice *dev,
+						   bool *okp);
 
 /**
  * bootstd_get_prefixes() - Get the filename-prefixes list