bootstd: Add the bootmeth uclass and helpers

A bootmeth is a method of locating an operating system. For now, just
add the uclass itself. Drivers for particular bootmeths are added later.

If no bootmeths devices are included in the devicetree, create them
automatically. This avoids the need for boilerplate in the devicetree
files.

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

1 files changed, 234 insertions, 0 deletions

diff --git a/include/bootmeth.h b/include/bootmeth.h
new file mode 100644
index 0000000000..484e503e33
--- /dev/null
+++ b/include/bootmeth.h
@@ -0,0 +1,234 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#ifndef __bootmeth_h
+#define __bootmeth_h
+
+struct blk_desc;
+struct bootflow;
+struct bootflow_iter;
+struct udevice;
+
+/**
+ * struct bootmeth_uc_plat - information the uclass keeps about each bootmeth
+ *
+ * @desc: A long description of the bootmeth
+ */
+struct bootmeth_uc_plat {
+	const char *desc;
+};
+
+/** struct bootmeth_ops - Operations for boot methods */
+struct bootmeth_ops {
+	/**
+	 * check_supported() - check if a bootmeth supports this bootflow
+	 *
+	 * This is optional. If not provided, the bootdev is assumed to be
+	 * supported
+	 *
+	 * The bootmeth can check the bootdev (e.g. to make sure it is a
+	 * network device) or the partition information. The following fields
+	 * in @iter are available:
+	 *
+	 *   name, dev, state, part
+	 *   max_part may be set if part != 0 (i.e. there is a valid partition
+	 *      table). Otherwise max_part is 0
+	 *   method is available but is the same as @dev
+	 *   the partition has not yet been read, nor has the filesystem been
+	 *   checked
+	 *
+	 * It may update only the flags in @iter
+	 *
+	 * @dev:	Bootmethod device to check against
+	 * @iter:	On entry, provides bootdev, hwpart, part
+	 * Return: 0 if OK, -ENOTSUPP if this bootdev is not supported
+	 */
+	int (*check)(struct udevice *dev, struct bootflow_iter *iter);
+
+	/**
+	 * read_bootflow() - read a bootflow for a device
+	 *
+	 * @dev:	Bootmethod device to use
+	 * @bflow:	On entry, provides dev, hwpart, part and method.
+	 *	Returns updated bootflow if found
+	 * Return: 0 if OK, -ve on error
+	 */
+	int (*read_bootflow)(struct udevice *dev, struct bootflow *bflow);
+
+	/**
+	 * read_file() - read a file needed for a bootflow
+	 *
+	 * Read a file from the same place as the bootflow came from
+	 *
+	 * @dev:	Bootmethod device to use
+	 * @bflow:	Bootflow providing info on where to read from
+	 * @file_path:	Path to file (may be absolute or relative)
+	 * @addr:	Address to load file
+	 * @sizep:	On entry provides the maximum permitted size; on exit
+	 *		returns the size of the file
+	 * Return: 0 if OK, -ENOSPC if the file is too large for @sizep, other
+	 *	-ve value if something else goes wrong
+	 */
+	int (*read_file)(struct udevice *dev, struct bootflow *bflow,
+			 const char *file_path, ulong addr, ulong *sizep);
+
+	/**
+	 * boot() - boot a bootflow
+	 *
+	 * @dev:	Bootmethod device to boot
+	 * @bflow:	Bootflow to boot
+	 * Return: does not return on success, since it should boot the
+	 *	Operating Systemn. Returns -EFAULT if that fails, -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, other -ve on other error
+	 */
+	int (*boot)(struct udevice *dev, struct bootflow *bflow);
+};
+
+#define bootmeth_get_ops(dev)  ((struct bootmeth_ops *)(dev)->driver->ops)
+
+/**
+ * bootmeth_check() - check if a bootmeth supports this bootflow
+ *
+ * This is optional. If not provided, the bootdev is assumed to be
+ * supported
+ *
+ * The bootmeth can check the bootdev (e.g. to make sure it is a
+ * network device) or the partition information. The following fields
+ * in @iter are available:
+ *
+ *   name, dev, state, part
+ *   max_part may be set if part != 0 (i.e. there is a valid partition
+ *      table). Otherwise max_part is 0
+ *   method is available but is the same as @dev
+ *   the partition has not yet been read, nor has the filesystem been
+ *   checked
+ *
+ * It may update only the flags in @iter
+ *
+ * @dev:	Bootmethod device to check against
+ * @iter:	On entry, provides bootdev, hwpart, part
+ * Return: 0 if OK, -ENOTSUPP if this bootdev is not supported
+ */
+int bootmeth_check(struct udevice *dev, struct bootflow_iter *iter);
+
+/**
+ * bootmeth_read_bootflow() - set up a bootflow for a device
+ *
+ * @dev:	Bootmethod device to check
+ * @bflow:	On entry, provides dev, hwpart, part and method.
+ *	Returns updated bootflow if found
+ * Return: 0 if OK, -ve on error
+ */
+int bootmeth_read_bootflow(struct udevice *dev, struct bootflow *bflow);
+
+/**
+ * bootmeth_read_file() - read a file needed for a bootflow
+ *
+ * Read a file from the same place as the bootflow came from
+ *
+ * @dev:	Bootmethod device to use
+ * @bflow:	Bootflow providing info on where to read from
+ * @file_path:	Path to file (may be absolute or relative)
+ * @addr:	Address to load file
+ * @sizep:	On entry provides the maximum permitted size; on exit
+ *		returns the size of the file
+ * Return: 0 if OK, -ENOSPC if the file is too large for @sizep, other
+ *	-ve value if something else goes wrong
+ */
+int bootmeth_read_file(struct udevice *dev, struct bootflow *bflow,
+		       const char *file_path, ulong addr, ulong *sizep);
+
+/**
+ * bootmeth_boot() - boot a bootflow
+ *
+ * @dev:	Bootmethod device to boot
+ * @bflow:	Bootflow to boot
+ * Return: does not return on success, since it should boot the
+ *	Operating Systemn. Returns -EFAULT if that fails, other -ve on
+ *	other error
+ */
+int bootmeth_boot(struct udevice *dev, struct bootflow *bflow);
+
+/**
+ * bootmeth_setup_iter_order() - Set up the ordering of bootmeths to scan
+ *
+ * This sets up the ordering information in @iter, based on the selected
+ * ordering of the bootmethds in bootstd_priv->bootmeth_order. If there is no
+ * ordering there, then all bootmethods are added
+ *
+ * @iter: Iterator to update with the order
+ * Return: 0 if OK, -ENOENT if no bootdevs, -ENOMEM if out of memory, other -ve
+ *	on other error
+ */
+int bootmeth_setup_iter_order(struct bootflow_iter *iter);
+
+/**
+ * bootmeth_set_order() - Set the bootmeth order
+ *
+ * This selects the ordering to use for bootmeths
+ *
+ * @order_str: String containing the ordering. This is a comma-separate list of
+ * bootmeth-device names, e.g. "syslinux,efi". If empty then a default ordering
+ * is used, based on the sequence number of devices (i.e. using aliases)
+ * Return: 0 if OK, -ENODEV if an unknown bootmeth is mentioned, -ENOMEM if
+ * out of memory, -ENOENT if there are no bootmeth devices
+ */
+int bootmeth_set_order(const char *order_str);
+
+/**
+ * bootmeth_try_file() - See we can access a given file
+ *
+ * Check for a file with a given name. If found, the filename is allocated in
+ * @bflow
+ *
+ * Sets the state to BOOTFLOWST_FILE on success. It also calls
+ * fs_set_blk_dev_with_part() so that this does not need to be done by the
+ * caller before reading the file.
+ *
+ * @bflow: Information about file to try
+ * @desc: Block descriptor to read from
+ * @prefix: Filename prefix to prepend to @fname (NULL for none)
+ * @fname: Filename to read
+ * Return: 0 if OK, -ENOMEM if not enough memory to allocate bflow->fname,
+ * other -ve value on other error
+ */
+int bootmeth_try_file(struct bootflow *bflow, struct blk_desc *desc,
+		      const char *prefix, const char *fname);
+
+/**
+ * bootmeth_alloc_file() - Allocate and read a bootflow file
+ *
+ * Allocates memory for a bootflow file and reads it in. Sets the state to
+ * BOOTFLOWST_READY on success
+ *
+ * Note that fs_set_blk_dev_with_part() must have been called previously.
+ *
+ * @bflow: Information about file to read
+ * @size_limit: Maximum file size to permit
+ * @align: Allocation alignment (1 for unaligned)
+ * Return: 0 if OK, -E2BIG if file is too large, -ENOMEM if out of memory,
+ *	other -ve on other error
+ */
+int bootmeth_alloc_file(struct bootflow *bflow, uint size_limit, uint align);
+
+/**
+ * bootmeth_common_read_file() - Common handler for reading a file
+ *
+ * Reads a named file from the same location as the bootflow file.
+ *
+ * @dev: bootmeth device to read from
+ * @bflow: Bootflow information
+ * @file_path: Path to file
+ * @addr: Address to load file to
+ * @sizep: On entry, the maximum file size to accept, on exit the actual file
+ *	size read
+ */
+int bootmeth_common_read_file(struct udevice *dev, struct bootflow *bflow,
+			      const char *file_path, ulong addr, ulong *sizep);
+
+#endif