From: Simon Glass <sjg@chromium.org> Provide a struct iov_iter and some related functions to encapsulate an iterator used when reading and writing files. This will be used with the new 'file' uclass. While it is modelled on Linux, I/O vectors have been omitted for now. These can be added later without updating the interface used by the uclass. Signed-off-by: Simon Glass <sjg@chromium.org> --- MAINTAINERS | 1 + include/iovec.h | 85 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 86 insertions(+) create mode 100644 include/iovec.h diff --git a/MAINTAINERS b/MAINTAINERS index 6af09911bdd..9fcff19857d 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -1200,6 +1200,7 @@ F: fs/dir-uclass.c F: include/dir.h F: include/fpga.h F: include/fs.h +F: include/iovec.h F: test/dm/fpga.c FLATTENED DEVICE TREE diff --git a/include/iovec.h b/include/iovec.h new file mode 100644 index 00000000000..f814f80a3da --- /dev/null +++ b/include/iovec.h @@ -0,0 +1,85 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Iterator for I/O, modelled on Linux but significantly simplified + * + * Copyright 2025 Simon Glass <sjg@chromium.org> + */ + +#ifndef __IOVEC_H +#define __IOVEC_H + +#include <linux/types.h> + +/** + * enum iov_type_t - defines the type of this I/O vector + * + * @OIV_BUF: Simple buffer with a size + */ +enum iov_type_t { + OIV_BUF, +}; + +/** + * struct iov_iter - holds an interator for I/O + * + * Do not use this directly. Instead, call copy_to_iter() + * + * Note that this is much simpler than the Linux version, but can be extended + * later as needed. It is introduced so that we can use the desired API for + * read(), etc. It is also commented properly. + * + * @type: Type of the iterator (always OIV_BUF) + * @data_source: true if this iterator produces data, false if it consumes it + * @offset: Current offset within the buffer + * @buf: Contiguous data buffer to use (other things could be added to the + * union later) + * @count: Size of data buffer + */ +struct iov_iter { + enum iov_type_t type; + bool data_source; + ssize_t offset; + union { + void *ubuf; + }; + ssize_t count; +}; + +/** + * iter_iov_ptr() - Get a pointer to the current position + * + * @iter: Iterator to examine + * Return: pointer to the start of the buffer portion to read/write + */ +static inline void *iter_iov_ptr(const struct iov_iter *iter) +{ + return iter->ubuf + iter->offset; +}; + +/** + * iter_iov_avail() - Get the number of bytes available at the current postiion + * + * @iter: iterator to examine + * Return: number of bytes which can be read/written + */ +static inline ssize_t iter_iov_avail(const struct iov_iter *iter) +{ + return iter->count - iter->offset; +}; + +static inline void iter_ubuf(struct iov_iter *iter, bool data_source, void *buf, + size_t count) +{ + *iter = (struct iov_iter) { + .data_source = data_source, + .ubuf = buf, + .count = count, + }; +} + +static inline void iter_advance(struct iov_iter *iter, size_t len) +{ + iter->offset += len; +} + +#endif -- 2.43.0