bootstd: Add the concept of a bootflow

A bootflow encapsulates the process used to boot an operating system.
It typically has a control file (such as extlinux.conf) and information
about which 'bootdev' it came from.

Add the header file for this first, since it is needed by all other
files.

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

2 files changed, 265 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index f7665fc..d6d4557 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -693,6 +693,11 @@ M:	Simon Glass <sjg@chromium.org>
 S:	Maintained
 F:	tools/binman/
 
+BOOTDEVICE
+M:	Simon Glass <sjg@chromium.org>
+S:	Maintained
+F:	include/bootflow.h
+
 BTRFS
 M:	Marek Behun <marek.behun@nic.cz>
 R:	Qu Wenruo <wqu@suse.com>
diff --git a/include/bootflow.h b/include/bootflow.h
new file mode 100644
index 0000000..6e9a729
--- /dev/null
+++ b/include/bootflow.h
@@ -0,0 +1,260 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#ifndef __bootflow_h
+#define __bootflow_h
+
+#include <linux/list.h>
+
+/**
+ * enum bootflow_state_t - states that a particular bootflow can be in
+ *
+ * Only bootflows in state BOOTFLOWST_READY can be used to boot.
+ *
+ * See bootflow_state[] for the names for each of these
+ */
+enum bootflow_state_t {
+	BOOTFLOWST_BASE,	/**< Nothing known yet */
+	BOOTFLOWST_MEDIA,	/**< Media exists */
+	BOOTFLOWST_PART,	/**< Partition exists */
+	BOOTFLOWST_FS,		/**< Filesystem exists */
+	BOOTFLOWST_FILE,	/**< Bootflow file exists */
+	BOOTFLOWST_READY,	/**< Bootflow file loaded */
+
+	BOOTFLOWST_COUNT
+};
+
+/**
+ * struct bootflow - information about a bootflow
+ *
+ * This is connected into two separate linked lists:
+ *
+ *   bm_sibling - links all bootflows in the same bootdev
+ *   glob_sibling - links all bootflows in all bootdevs
+ *
+ * @bm_node: Points to siblings in the same bootdev
+ * @glob_node: Points to siblings in the global list (all bootdev)
+ * @dev: Bootdevice device which produced this bootflow
+ * @blk: Block device which contains this bootflow, NULL if this is a network
+ *	device
+ * @part: Partition number (0 for whole device)
+ * @fs_type: Filesystem type (FS_TYPE...) if this is fixed by the media, else 0.
+ *	For example, the sandbox host-filesystem bootdev sets this to
+ *	FS_TYPE_SANDBOX
+ * @method: Bootmethod device used to perform the boot and read files
+ * @name: Name of bootflow (allocated)
+ * @state: Current state (enum bootflow_state_t)
+ * @subdir: Subdirectory to fetch files from (with trailing /), or NULL if none
+ * @fname: Filename of bootflow file (allocated)
+ * @buf: Bootflow file contents (allocated)
+ * @size: Size of bootflow file in bytes
+ * @err: Error number received (0 if OK)
+ */
+struct bootflow {
+	struct list_head bm_node;
+	struct list_head glob_node;
+	struct udevice *dev;
+	struct udevice *blk;
+	int part;
+	int fs_type;
+	struct udevice *method;
+	char *name;
+	enum bootflow_state_t state;
+	char *subdir;
+	char *fname;
+	char *buf;
+	int size;
+	int err;
+};
+
+/**
+ * enum bootflow_flags_t - flags for the bootflow iterator
+ *
+ * @BOOTFLOWF_FIXED: Only used fixed/internal media
+ * @BOOTFLOWF_SHOW: Show each bootdev before scanning it
+ * @BOOTFLOWF_ALL: Return bootflows with errors as well
+ * @BOOTFLOWF_SINGLE_DEV: Just scan one bootmeth
+ */
+enum bootflow_flags_t {
+	BOOTFLOWF_FIXED		= 1 << 0,
+	BOOTFLOWF_SHOW		= 1 << 1,
+	BOOTFLOWF_ALL		= 1 << 2,
+	BOOTFLOWF_SINGLE_DEV	= 1 << 3,
+};
+
+/**
+ * struct bootflow_iter - state for iterating through bootflows
+ *
+ * This starts at with the first bootdev/partition/bootmeth and can be used to
+ * iterate through all of them.
+ *
+ * Iteration starts with the bootdev. The first partition (0, i.e. whole device)
+ * is scanned first. For partition 0, it iterates through all the available
+ * bootmeths to see which one(s) can provide a bootflow. Then it moves to
+ * parition 1 (if there is one) and the process continues. Once all partitions
+ * are examined, it moves to the next bootdev.
+ *
+ * Initially @max_part is 0, meaning that only the whole device (@part=0) can be
+ * used. During scanning, if a partition table is found, then @max_part is
+ * updated to a larger value, no less than the number of available partitions.
+ * This ensures that iteration works through all partitions on the bootdev.
+ *
+ * @flags: Flags to use (see enum bootflow_flags_t)
+ * @dev: Current bootdev
+ * @part: Current partition number (0 for whole device)
+ * @method: Current bootmeth
+ * @max_part: Maximum hardware partition number in @dev, 0 if there is no
+ *	partition table
+ * @err: Error obtained from checking the last iteration. This is used to skip
+ *	forward (e.g. to skip the current partition because it is not valid)
+ *	-ESHUTDOWN: try next bootdev
+ * @num_devs: Number of bootdevs in @dev_order
+ * @cur_dev: Current bootdev number, an index into @dev_order[]
+ * @dev_order: List of bootdevs to scan, in order of priority. The scan starts
+ *	with the first one on the list
+ * @num_methods: Number of bootmeth devices in @method_order
+ * @cur_method: Current method number, an index into @method_order
+ * @method_order: List of bootmeth devices to use, in order
+ */
+struct bootflow_iter {
+	int flags;
+	struct udevice *dev;
+	int part;
+	struct udevice *method;
+	int max_part;
+	int err;
+	int num_devs;
+	int cur_dev;
+	struct udevice **dev_order;
+	int num_methods;
+	int cur_method;
+	struct udevice **method_order;
+};
+
+/**
+ * bootflow_iter_init() - Reset a bootflow iterator
+ *
+ * This sets everything to the starting point, ready for use.
+ *
+ * @iter: Place to store private info (inited by this call)
+ * @flags: Flags to use (see enum bootflow_flags_t)
+ */
+void bootflow_iter_init(struct bootflow_iter *iter, int flags);
+
+/**
+ * bootflow_iter_uninit() - Free memory used by an interator
+ *
+ * @iter:	Iterator to free
+ */
+void bootflow_iter_uninit(struct bootflow_iter *iter);
+
+/**
+ * bootflow_scan_bootdev() - find the first bootflow in a bootdev
+ *
+ * If @flags includes BOOTFLOWF_ALL then bootflows with errors are returned too
+ *
+ * @dev:	Boot device to scan, NULL to work through all of them until it
+ *	finds one that * can supply a bootflow
+ * @iter:	Place to store private info (inited by this call)
+ * @flags:	Flags for bootdev (enum bootflow_flags_t)
+ * @bflow:	Place to put the bootflow if found
+ * Return: 0 if found,  -ENODEV if no device, other -ve on other error
+ *	(iteration can continue)
+ */
+int bootflow_scan_bootdev(struct udevice *dev, struct bootflow_iter *iter,
+			  int flags, struct bootflow *bflow);
+
+/**
+ * bootflow_scan_first() - find the first bootflow
+ *
+ * This works through the available bootdev devices until it finds one that
+ * can supply a bootflow. It then returns that
+ *
+ * If @flags includes BOOTFLOWF_ALL then bootflows with errors are returned too
+ *
+ * @iter:	Place to store private info (inited by this call), with
+ * @flags:	Flags for bootdev (enum bootflow_flags_t)
+ * @bflow:	Place to put the bootflow if found
+ * Return: 0 if found, -ENODEV if no device, other -ve on other error (iteration
+ *	can continue)
+ */
+int bootflow_scan_first(struct bootflow_iter *iter, int flags,
+			struct bootflow *bflow);
+
+/**
+ * bootflow_scan_next() - find the next bootflow
+ *
+ * This works through the available bootdev devices until it finds one that
+ * can supply a bootflow. It then returns that bootflow
+ *
+ * @iter:	Private info (as set up by bootflow_scan_first())
+ * @bflow:	Place to put the bootflow if found
+ * Return: 0 if found, -ENODEV if no device, -ESHUTDOWN if no more bootflows,
+ *	other -ve on other error (iteration can continue)
+ */
+int bootflow_scan_next(struct bootflow_iter *iter, struct bootflow *bflow);
+
+/**
+ * bootflow_first_glob() - Get the first bootflow from the global list
+ *
+ * Returns the first bootflow in the global list, no matter what bootflow it is
+ * attached to
+ *
+ * @bflowp: Returns a pointer to the bootflow
+ * Return: 0 if found, -ENOENT if there are no bootflows
+ */
+int bootflow_first_glob(struct bootflow **bflowp);
+
+/**
+ * bootflow_next_glob() - Get the next bootflow from the global list
+ *
+ * Returns the next bootflow in the global list, no matter what bootflow it is
+ * attached to
+ *
+ * @bflowp: On entry, the last bootflow returned , e.g. from
+ *	bootflow_first_glob()
+ * Return: 0 if found, -ENOENT if there are no more bootflows
+ */
+int bootflow_next_glob(struct bootflow **bflowp);
+
+/**
+ * bootflow_free() - Free memory used by a bootflow
+ *
+ * This frees fields within @bflow, but not the @bflow pointer itself
+ */
+void bootflow_free(struct bootflow *bflow);
+
+/**
+ * bootflow_boot() - boot a bootflow
+ *
+ * @bflow: Bootflow to boot
+ * Return: -EPROTO if bootflow has not been loaded, -ENOSYS if the bootflow
+ *	type is not supported, -EFAULT if the boot returned without an error
+ *	when we are expecting it to boot, -ENOTSUPP if trying method resulted in
+ *	finding out that is not actually supported for this boot and should not
+ *	be tried again unless something changes
+ */
+int bootflow_boot(struct bootflow *bflow);
+
+/**
+ * bootflow_run_boot() - Try to boot a bootflow
+ *
+ * @iter: Current iteration (or NULL if none). Used to disable a bootmeth if the
+ *	boot returns -ENOTSUPP
+ * @bflow: Bootflow to boot
+ * Return: result of trying to boot
+ */
+int bootflow_run_boot(struct bootflow_iter *iter, struct bootflow *bflow);
+
+/**
+ * bootflow_state_get_name() - Get the name of a bootflow state
+ *
+ * @state: State to check
+ * Return: name, or "?" if invalid
+ */
+const char *bootflow_state_get_name(enum bootflow_state_t state);
+
+#endif