The device layer: devices by their numbers, and what calls them. More...

#include <core/system.h>
#include <dev/dev.h>
#include <fs/vfs.h>
#include <fs/posix.h>
#include <dev/blkcache.h>

Functions
static struct dev *	kdev_get (struct devid *dd)
	Returns the driver of a device number, picked by minor if the major's driver multiplexes several devices, or NULL if there is none.
struct fops *	kdev_fops (struct devid *dd)
	Returns the file operations of a device.
int	kdev_close (struct devid *dev)
	Closes a device: there is nothing to do.
ssize_t	kdev_bread (struct devid dd, off_t offset, size_t size, void buf)
	Reads bytes from a block device, at any offset: the driver reads whole blocks, and the partial blocks at either end go through a buffer.
ssize_t	kdev_bwrite (struct devid dd, off_t offset, size_t size, void buf)
	Writes bytes to a block device, at any offset: the driver writes whole blocks, and the partial blocks at either end are read, changed and written back.
static ssize_t	kdev_blk_io (struct devid dd, off_t offset, struct iobuf io, int write)
	Reads or writes a block device's bytes from or to an iobuf (user memory), a page at a time through a kernel buffer; kdev_bread() and kdev_bwrite() make blocks of them.
ssize_t	kdev_read (struct devid dd, off_t offset, struct iobuf io)
	Reads from a device: a character device through its driver, a block device in blocks.
ssize_t	kdev_write (struct devid dd, off_t offset, struct iobuf io)
	Writes to a device: a character device through its driver, a block device in blocks.
int	kdev_ioctl (struct devid dd, int request, void argp)
	Passes an ioctl() to a device's driver.
int	kdev_map (struct devid dd, struct vm_space vm_space, struct vm_entry *vm_entry)
	Maps a device into an address space (mmap() of a framebuffer).
int	kdev_file_open (struct devid dd, struct file file)
	Opens a device, through its driver's file operations.
ssize_t	kdev_file_read (struct devid dd, struct file file, struct iobuf *io)
	Reads an open device file, through its driver's file operations.
ssize_t	kdev_file_write (struct devid dd, struct file file, struct iobuf *io)
	Writes to an open device file, through its driver's file operations.
off_t	kdev_file_lseek (struct devid dd, struct file file, off_t offset, int whence)
	Moves an open device file's offset, through its driver's file operations.
ssize_t	kdev_file_close (struct devid dd, struct file file)
	Closes an open device file, through its driver's file operations.
int	kdev_file_ioctl (struct devid dd, struct file file, int request, void *argp)
	Passes an ioctl() on an open device file to its driver's file operations.
int	kdev_file_can_read (struct devid dd, struct file file, size_t size)
	Asks a device's driver whether a read wouldn't have to wait.
int	kdev_file_can_write (struct devid dd, struct file file, size_t size)
	Asks a device's driver whether a write wouldn't have to wait.
int	kdev_file_eof (struct devid dd, struct file file)
	Asks a device's driver whether a read that found no data is at the end of the file.
void	kdev_chrdev_register (devid_t major, struct dev *dev)
	Registers a driver as the character device of a major number.
int	kdev_sync (void)
	Writes what the block cache holds that was written, and what the block devices hold in their write caches, to the media.
void	kdev_blkdev_register (devid_t major, struct dev *dev)
	Registers a driver as the block device of a major number.
void	kdev_init ()
	Starts the device layer, at boot.

Variables
struct dev *	chrdev [256]
struct dev *	blkdev [256]

Detailed Description

The device layer: devices by their numbers, and what calls them.

A driver registers itself as the character or block device of a major number (kdev_chrdev_register(), kdev_blkdev_register()); a driver with several devices picks one by minor with its mux. The rest of the kernel reaches a device through these functions, by its number. Block devices are read and written in whole blocks: kdev_bread() and kdev_bwrite() make any range of bytes into blocks. See docs/kernel/devices.md.

Definition in file kdev.c.

Function Documentation

◆ kdev_blk_io()

ssize_t kdev_blk_io	(	struct devid *	dd,
		off_t	offset,
		struct iobuf *	io,
		int	write )

static

Reads or writes a block device's bytes from or to an iobuf (user memory), a page at a time through a kernel buffer; kdev_bread() and kdev_bwrite() make blocks of them.

Returns how many bytes were moved, or a negative errno if none were.

Definition at line 253 of file kdev.c.

References iobuf_in(), iobuf_out(), kdev_blk_io(), kdev_bread(), kdev_bwrite(), kfree(), kmalloc(), MIN, PAGE_SIZE, iobuf::resid, and dev::write.

Referenced by kdev_blk_io(), kdev_read(), and kdev_write().

◆ kdev_blkdev_register()

void kdev_blkdev_register	(	devid_t	major,
		struct dev *	dev )

Registers a driver as the block device of a major number.

A driver registered before for that major is replaced.

Parameters

major	the major number
dev	the driver

Definition at line 605 of file kdev.c.

References blkdev, kdev_blkdev_register(), dev::name, and printk().

Referenced by ata_probe(), kdev_blkdev_register(), and rd_probe().

◆ kdev_bread()

ssize_t kdev_bread	(	struct devid *	dd,
		off_t	offset,
		size_t	size,
		void *	buf )

Reads bytes from a block device, at any offset: the driver reads whole blocks, and the partial blocks at either end go through a buffer.

Parameters

dd	the device's number
offset	where to read from, in bytes
size	how many bytes to read
buf	where to put them

Returns: how many bytes were read (fewer at the device's end), or a negative errno if nothing could be

Definition at line 80 of file kdev.c.

References dev::bread, dev::getbs, kdev_bread(), kdev_get(), kfree(), kmalloc(), memcpy(), MIN, and NULL.

Referenced by kdev_blk_io(), and kdev_bread().

◆ kdev_bwrite()

ssize_t kdev_bwrite	(	struct devid *	dd,
		off_t	offset,
		size_t	size,
		void *	buf )

Writes bytes to a block device, at any offset: the driver writes whole blocks, and the partial blocks at either end are read, changed and written back.

Parameters

dd	the device's number
offset	where to write, in bytes
size	how many bytes to write
buf	the bytes

Returns: how many bytes were written, or a negative errno if nothing could be (-ENOSPC past the device's end)

Definition at line 165 of file kdev.c.

References dev::bread, dev::bwrite, dev::getbs, kdev_bwrite(), kdev_get(), kfree(), kmalloc(), memcpy(), MIN, and NULL.

Referenced by kdev_blk_io(), and kdev_bwrite().

◆ kdev_chrdev_register()

void kdev_chrdev_register	(	devid_t	major,
		struct dev *	dev )

Registers a driver as the character device of a major number.

A driver registered before for that major is replaced.

Parameters

major	the major number
dev	the driver

Definition at line 575 of file kdev.c.

References chrdev, kdev_chrdev_register(), dev::name, and printk().

Referenced by fbdev_probe(), kdev_chrdev_register(), memdev_probe(), ps2mouse_probe(), pty_init(), ttydev_probe(), and vt_probe().

◆ kdev_close()

int kdev_close ( struct devid * dev )

Closes a device: there is nothing to do.

Parameters

dev	the device's number

Returns: 0

Definition at line 64 of file kdev.c.

References kdev_close().

Referenced by kdev_close().

◆ kdev_file_can_read()

int kdev_file_can_read	(	struct devid *	dd,
		struct file *	file,
		size_t	size )

Asks a device's driver whether a read wouldn't have to wait.

Parameters

dd	the device's number
file	the open file
size	how much would be read

Returns: whether it can be read, or a negative errno

Definition at line 513 of file kdev.c.

References fops::can_read, dev::fops, kdev_file_can_read(), kdev_get(), and NULL.

Referenced by kdev_file_can_read(), and vfs_file_can_read().

◆ kdev_file_can_write()

int kdev_file_can_write	(	struct devid *	dd,
		struct file *	file,
		size_t	size )

Asks a device's driver whether a write wouldn't have to wait.

Parameters

dd	the device's number
file	the open file
size	how much would be written

Returns: whether it can be written, or a negative errno

Definition at line 534 of file kdev.c.

References fops::can_write, dev::fops, kdev_file_can_write(), kdev_get(), and NULL.

Referenced by kdev_file_can_write(), and vfs_file_can_write().

◆ kdev_file_close()

ssize_t kdev_file_close	(	struct devid *	dd,
		struct file *	file )

Closes an open device file, through its driver's file operations.

Parameters

dd	the device's number
file	the open file

Returns: 0, or a negative errno

Definition at line 468 of file kdev.c.

References fops::close, dev::fops, kdev_file_close(), kdev_get(), NULL, and posix_file_close().

Referenced by kdev_file_close(), and vfs_file_close().

◆ kdev_file_eof()

int kdev_file_eof	(	struct devid *	dd,
		struct file *	file )

Asks a device's driver whether a read that found no data is at the end of the file.

Parameters

dd	the device's number
file	the open file

Returns: whether it is, or a negative errno

Definition at line 555 of file kdev.c.

References fops::eof, dev::fops, kdev_file_eof(), kdev_get(), and NULL.

Referenced by kdev_file_eof(), and vfs_file_eof().

◆ kdev_file_ioctl()

int kdev_file_ioctl	(	struct devid *	dd,
		struct file *	file,
		int	request,
		void *	argp )

Passes an ioctl() on an open device file to its driver's file operations.

Parameters

dd	the device's number
file	the open file
request	the request
argp	its argument

Returns: what the driver returns, or a negative errno

Definition at line 492 of file kdev.c.

References dev::fops, fops::ioctl, kdev_file_ioctl(), kdev_get(), and NULL.

Referenced by kdev_file_ioctl(), and vfs_file_ioctl().

◆ kdev_file_lseek()

off_t kdev_file_lseek	(	struct devid *	dd,
		struct file *	file,
		off_t	offset,
		int	whence )

Moves an open device file's offset, through its driver's file operations.

Parameters

dd	the device's number
file	the open file
offset	the offset
whence	what it is from (SEEK_SET, SEEK_CUR, SEEK_END)

Returns: the new offset, or a negative errno (-ESPIPE for a device that can't seek)

Definition at line 447 of file kdev.c.

References dev::fops, kdev_file_lseek(), kdev_get(), fops::lseek, and NULL.

Referenced by kdev_file_lseek(), and vfs_file_lseek().

◆ kdev_file_open()

int kdev_file_open	(	struct devid *	dd,
		struct file *	file )

Opens a device, through its driver's file operations.

Parameters

dd	the device's number
file	the open file

Returns: 0, or a negative errno (-ENXIO if there is no such device)

Definition at line 381 of file kdev.c.

References dev::fops, kdev_file_open(), kdev_get(), NULL, and fops::open.

Referenced by ctty_open(), kdev_file_open(), and vfs_file_open().

◆ kdev_file_read()

ssize_t kdev_file_read	(	struct devid *	dd,
		struct file *	file,
		struct iobuf *	io )

Reads an open device file, through its driver's file operations.

Parameters

dd	the device's number
file	the open file
io	where to put what is read

Returns: how many bytes were read, or a negative errno

Definition at line 402 of file kdev.c.

References dev::fops, kdev_file_read(), kdev_get(), NULL, and fops::read.

Referenced by kdev_file_read(), and vfs_file_read().

◆ kdev_file_write()

ssize_t kdev_file_write	(	struct devid *	dd,
		struct file *	file,
		struct iobuf *	io )

Writes to an open device file, through its driver's file operations.

Parameters

dd	the device's number
file	the open file
io	what to write

Returns: how many bytes were written, or a negative errno

Definition at line 423 of file kdev.c.

References dev::fops, kdev_file_write(), kdev_get(), NULL, and fops::write.

Referenced by kdev_file_write(), and vfs_file_write().

◆ kdev_fops()

struct fops * kdev_fops ( struct devid * dd )

Returns the file operations of a device.

Parameters

dd	the device's number

Returns: its file operations, or NULL if there is no such device

Definition at line 52 of file kdev.c.

References dev::fops, kdev_fops(), kdev_get(), and NULL.

Referenced by kdev_fops(), and posix_file_read().

◆ kdev_get()

struct dev * kdev_get ( struct devid * dd )

inlinestatic

Returns the driver of a device number, picked by minor if the major's driver multiplexes several devices, or NULL if there is none.

Definition at line 26 of file kdev.c.

References blkdev, chrdev, kdev_get(), devid::major, dev::mux, NULL, and devid::type.

Referenced by kdev_bread(), kdev_bwrite(), kdev_file_can_read(), kdev_file_can_write(), kdev_file_close(), kdev_file_eof(), kdev_file_ioctl(), kdev_file_lseek(), kdev_file_open(), kdev_file_read(), kdev_file_write(), kdev_fops(), kdev_get(), kdev_ioctl(), kdev_map(), kdev_read(), and kdev_write().

◆ kdev_init()

void kdev_init ( void )

Starts the device layer, at boot.

It has nothing to set up: the drivers register themselves.

Definition at line 615 of file kdev.c.

References kdev_init(), and printk().

Referenced by kdev_init(), and kmain().

◆ kdev_ioctl()

int kdev_ioctl	(	struct devid *	dd,
		int	request,
		void *	argp )

Passes an ioctl() to a device's driver.

Parameters

dd	the device's number
request	the request
argp	its argument

Returns: what the driver returns, or -ENXIO if it takes no ioctl()

Definition at line 340 of file kdev.c.

References dev::ioctl, kdev_get(), kdev_ioctl(), and NULL.

Referenced by kdev_ioctl(), and vfs_ioctl().

◆ kdev_map()

int kdev_map	(	struct devid *	dd,
		struct vm_space *	vm_space,
		struct vm_entry *	vm_entry )

Maps a device into an address space (mmap() of a framebuffer).

Parameters

dd	the device's number
vm_space	the address space
vm_entry	the mapping

Returns: 0, or a negative errno (-ENXIO if the device can't be mapped)

Definition at line 361 of file kdev.c.

References kdev_get(), kdev_map(), dev::map, and NULL.

Referenced by kdev_map(), and vfs_map().

◆ kdev_read()

ssize_t kdev_read	(	struct devid *	dd,
		off_t	offset,
		struct iobuf *	io )

Reads from a device: a character device through its driver, a block device in blocks.

Parameters

dd	the device's number
offset	where to read from, in bytes
io	where to put what is read

Returns: how many bytes were read, or a negative errno

Definition at line 297 of file kdev.c.

References dev::bread, kdev_blk_io(), kdev_get(), kdev_read(), NULL, dev::read, and devid::type.

Referenced by kdev_read(), and vfs_read_io().

◆ kdev_sync()

int kdev_sync ( void )

Writes what the block cache holds that was written, and what the block devices hold in their write caches, to the media.

Returns: 0, or a negative errno if a write failed

Definition at line 587 of file kdev.c.

References blkcache_flush(), blkdev, kdev_sync(), and dev::sync.

Referenced by kdev_sync(), kernel_reboot(), and sys_sync().

◆ kdev_write()

ssize_t kdev_write	(	struct devid *	dd,
		off_t	offset,
		struct iobuf *	io )

Writes to a device: a character device through its driver, a block device in blocks.

Parameters

dd	the device's number
offset	where to write, in bytes
io	what to write

Returns: how many bytes were written, or a negative errno

Definition at line 319 of file kdev.c.

References dev::bwrite, kdev_blk_io(), kdev_get(), kdev_write(), NULL, devid::type, and dev::write.

Referenced by kdev_write(), and vfs_write_io().

Variable Documentation

◆ blkdev

struct dev* blkdev[256]

Definition at line 22 of file kdev.c.

Referenced by kdev_blkdev_register(), kdev_get(), kdev_sync(), and procfs_devices().

◆ chrdev

struct dev* chrdev[256]

Definition at line 21 of file kdev.c.

Referenced by kdev_chrdev_register(), kdev_get(), and procfs_devices().

Functions

Variables

Detailed Description

Function Documentation

◆ kdev_blk_io()

◆ kdev_blkdev_register()

◆ kdev_bread()

◆ kdev_bwrite()

◆ kdev_chrdev_register()

◆ kdev_close()

◆ kdev_file_can_read()

◆ kdev_file_can_write()

◆ kdev_file_close()

◆ kdev_file_eof()

◆ kdev_file_ioctl()

◆ kdev_file_lseek()

◆ kdev_file_open()

◆ kdev_file_read()

◆ kdev_file_write()

◆ kdev_fops()

◆ kdev_get()

◆ kdev_init()

◆ kdev_ioctl()

◆ kdev_map()

◆ kdev_read()

◆ kdev_sync()

◆ kdev_write()

Variable Documentation

◆ blkdev

◆ chrdev