uart.c File Reference

Serial ports as terminals: /dev/ttyS0 and up (character device 4, 64 and up). More...

#include <core/system.h>
#include <dev/dev.h>
#include <dev/tty.h>
#include <dev/uart.h>
#include <fs/posix.h>
#include <ds/queue.h>
#include <ds/ringbuf.h>
#include <sys/sched.h>

Go to the source code of this file.

Macros
#define	UART_BUF   64
#define	UART_RING   4096
#define	UART_MAX   192

Functions
void	uart_receive_handler (struct uart *u, size_t size)
	Takes characters a UART received, and gives them to its terminal.
void	uart_transmit_handler (struct uart *u, size_t size)
	Sends characters that the terminal output to its UART.
ssize_t	uart_master_write (struct tty *tty, size_t size, void *buf)
	Takes the terminal's output, and sends it to the UART at once: the UART drivers don't use a "transmitter empty" interrupt.
static void	uart_input_flush (struct tty *tty)
	Drops the input waiting to be read (tcflush()).
ssize_t	uart_slave_write (struct tty *tty, size_t size, void *buf)
	Takes the terminal's input, after its line editing, for the readers of the UART's device.
static struct uart *	uart_get (devid_t minor)
	Returns the UART of a minor (they start at 64), or NULL if there's none.
ssize_t	uart_read (struct devid *dd, off_t offset, struct iobuf *io)
	Reads a UART's terminal.
ssize_t	uart_write (struct devid *dd, off_t offset, struct iobuf *io)
	Writes to a UART's terminal.
static int	uart_file_eof (struct file *file)
	Returns whether a read that found no data is at the end of the file (the terminal says, from its mode).
static uint64_t	uart_read_timeout (struct file *file)
	Returns how long a read may wait for data, from the terminal's mode (VTIME), or 0 for no limit.
static int	uart_can_read (struct file *file, size_t size)
	Returns whether a read wouldn't have to wait.
int	uart_ioctl (struct devid *dd, int request, void *argp)
	Handles a UART terminal's ioctl()s, which are the terminal's.
static int	uart_setup (struct uart *u, struct vnode *vnode)
	Sets a UART up the first time it is opened: its rings, its terminal, and the UART itself.
int	uart_file_open (struct file *file)
	Opens a UART's device, setting the UART up the first time.
int	uart_register (int id, struct uart *u)
	Registers a UART, as /dev/ttyS<id>.

Variables
static struct uart *	devices [192] = {0}
struct dev	uart

Detailed Description

Serial ports as terminals: /dev/ttyS0 and up (character device 4, 64 and up).

A UART driver (8250, PL011) registers its UARTs here, and this layer makes each one a terminal: it connects the UART to the terminal layer (generic.c), which does the line editing, with a ring each way. What the UART receives goes to the terminal; what the terminal outputs goes to the UART. A UART is set up the first time it is opened.

Definition in file uart.c.

Macro Definition Documentation

UART_BUF

#define UART_BUF   64

Definition at line 21 of file uart.c.

Referenced by uart_receive_handler().

UART_MAX

#define UART_MAX   192

Definition at line 115 of file uart.c.

Referenced by uart_get().

UART_RING

#define UART_RING   4096

Definition at line 25 of file uart.c.

Referenced by uart_setup().

Function Documentation

uart_can_read()

int uart_can_read ( struct file * file, size_t size )

static

Returns whether a read wouldn't have to wait.

Definition at line 195 of file uart.c.

References DEV_MINOR, uart::in, uart::tty, tty_can_read(), uart_can_read(), and uart_get().

Referenced by uart_can_read().

uart_file_eof()

int uart_file_eof ( struct file * file )

static

Returns whether a read that found no data is at the end of the file (the terminal says, from its mode).

Definition at line 180 of file uart.c.

References DEV_MINOR, uart::tty, tty_eof(), uart_file_eof(), and uart_get().

Referenced by uart_file_eof().

uart_file_open()

int uart_file_open

(

struct file *

file

)

Opens a UART's device, setting the UART up the first time.

Parameters

file	the file being opened

Returns

0, -ENXIO if no UART has that minor, or a negative errno

Definition at line 251 of file uart.c.

References DEV_MINOR, uart::read_queue, uart::tty, tty_open(), uart_file_open(), uart_get(), uart_setup(), and uart::write_queue.

Referenced by uart_file_open().

uart_get()

struct uart * uart_get ( devid_t minor )

static

Returns the UART of a minor (they start at 64), or NULL if there's none.

Without virtual terminals, minor 1 (/dev/console) is the first UART too.

Definition at line 120 of file uart.c.

References devices, NULL, uart_get(), and UART_MAX.

Referenced by uart_can_read(), uart_file_eof(), uart_file_open(), uart_get(), uart_ioctl(), uart_read(), uart_read_timeout(), and uart_write().

uart_input_flush()

void uart_input_flush ( struct tty * tty )

static

Drops the input waiting to be read (tcflush()).

Definition at line 91 of file uart.c.

References uart::in, tty::p, and uart_input_flush().

Referenced by uart_input_flush(), and uart_setup().

uart_ioctl()

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

Handles a UART terminal's ioctl()s, which are the terminal's.

Parameters

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

Returns

what the request returns, or a negative errno

Definition at line 209 of file uart.c.

References devid::minor, uart::tty, tty_ioctl(), uart_get(), and uart_ioctl().

Referenced by uart_ioctl().

uart_master_write()

ssize_t uart_master_write	(	struct tty *	tty,
		size_t	size,
		void *	buf )

Takes the terminal's output, and sends it to the UART at once: the UART drivers don't use a "transmitter empty" interrupt.

Parameters

tty	the terminal
size	the output's size, in bytes
buf	the output

Returns

how much of it was taken

Definition at line 82 of file uart.c.

References uart::out, tty::p, uart_master_write(), and uart_transmit_handler().

Referenced by uart_master_write(), and uart_setup().

uart_read()

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

Reads a UART's terminal.

A process of a background group gets SIGTTIN instead.

Parameters

dd	the device's number
offset	not used: a terminal has no offset
io	where to put what is read

Returns

how much was read, or a negative errno

Definition at line 143 of file uart.c.

References uart::in, devid::minor, iobuf::resid, uart::tty, tty_background(), uart_get(), and uart_read().

Referenced by uart_read().

uart_read_timeout()

uint64_t uart_read_timeout ( struct file * file )

static

Returns how long a read may wait for data, from the terminal's mode (VTIME), or 0 for no limit.

Definition at line 188 of file uart.c.

References DEV_MINOR, uart::tty, tty_read_timeout(), uart_get(), and uart_read_timeout().

Referenced by uart_read_timeout().

uart_receive_handler()

void uart_receive_handler	(	struct uart *	u,
		size_t	size )

Takes characters a UART received, and gives them to its terminal.

The UART's driver calls it from its interrupt handler.

Parameters

u	the UART
size	how many characters to take from it

Definition at line 35 of file uart.c.

References MIN, uart::read_queue, uart::receive, uart::tty, tty_master_write(), UART_BUF, uart_receive_handler(), and waitq_wakeup().

Referenced by pl011_irq(), uart_8250_irq(), and uart_receive_handler().

uart_register()

int uart_register	(	int	id,
		struct uart *	u )

Registers a UART, as /dev/ttyS<id>.

Parameters

id	its number (below 192), or -1 for the first free one
u	the UART

Returns

its number, -EINVAL if id is too big, or -ENOSPC if every number is taken

Definition at line 278 of file uart.c.

References devices, uart::name, printk(), and uart_register().

Referenced by pl011_init(), uart_8250_attach(), and uart_register().

uart_setup()

int uart_setup ( struct uart * u, struct vnode * vnode )

static

Sets a UART up the first time it is opened: its rings, its terminal, and the UART itself.

Returns 0 or a negative errno.

Definition at line 218 of file uart.c.

References curproc, uart::in, uart::init, tty::input_flush, NULL, uart::out, vnode::ref, uart::tty, tty_new(), uart_input_flush(), uart_master_write(), UART_RING, uart_setup(), uart_slave_write(), tty::vnode, and uart::vnode.

Referenced by uart_file_open(), and uart_setup().

uart_slave_write()

ssize_t uart_slave_write	(	struct tty *	tty,
		size_t	size,
		void *	buf )

Takes the terminal's input, after its line editing, for the readers of the UART's device.

Parameters

tty	the terminal
size	the input's size, in bytes
buf	the input

Returns

how much of it was taken

Definition at line 109 of file uart.c.

References uart::in, tty::p, and uart_slave_write().

Referenced by uart_setup(), and uart_slave_write().

uart_transmit_handler()

void uart_transmit_handler	(	struct uart *	u,
		size_t	size )

Sends characters that the terminal output to its UART.

Parameters

u	the UART
size	how many characters to send, at most

Definition at line 59 of file uart.c.

References MIN, uart::out, uart::transmit, uart_transmit_handler(), waitq_wakeup(), and uart::write_queue.

Referenced by uart_8250_irq(), uart_master_write(), and uart_transmit_handler().

uart_write()

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

Writes to a UART's terminal.

With TOSTOP set, a process of a background group gets SIGTTOU instead.

Parameters

dd	the device's number
offset	not used: a terminal has no offset
io	what to write

Returns

how much was written, or a negative errno

Definition at line 163 of file uart.c.

References devid::minor, tty::tios, uart::tty, tty_background(), tty_slave_write(), tty_write_iobuf(), uart_get(), and uart_write().

Referenced by uart_write().

Variable Documentation

devices

struct uart* devices[192] = {0}

static

Definition at line 26 of file uart.c.

Referenced by uart_get(), and uart_register().

uart

struct dev uart

Initial value:

         = {
    .name = "uart",
 
    .read  = uart_read,
    .write = uart_write,
    .ioctl = uart_ioctl,
 
    .fops = {
        .open  = uart_file_open,
        .read  = posix_file_read,
        .write = posix_file_write,
        .ioctl = posix_file_ioctl,
 
        .can_read  = uart_can_read,
        .can_write = __vfs_can_always,  
        .eof       = uart_file_eof,
        .read_timeout = uart_read_timeout,
    },
}

Definition at line 302 of file uart.c.