UART Generic Functions

These UART functions are implemented the same way regardless of the exact type of UART. More...

Functions
syscall	kprintf (const char *format,...)
syscall	kvprintf (const char *format, va_list ap)
devcall	uartControl (device *devptr, int func, long arg1, long arg2)
devcall	uartGetc (device *devptr)
devcall	uartInit (device *devptr)
devcall	uartPutc (device *devptr, char ch)
devcall	uartRead (device *devptr, void *buf, uint len)
void	uartStat (ushort uartnum)
devcall	uartWrite (device *devptr, const void *buf, uint len)

Variables
struct uart	uarttab [NUART]

Detailed Description

These UART functions are implemented the same way regardless of the exact type of UART.

Function Documentation

syscall kprintf	(	const char *	format,
			...
	)

kernel printf: Multicore-safe (by mutex locks), formatted, synchronous output to SERIAL0.

Parameters

format	The format string. Not all standard format specifiers are supported by this implementation. See _doprnt() for a description of supported conversion specifications.
...	Arguments matching those in the format string.

Returns

The number of characters written.

syscall kvprintf	(	const char *	format,
		va_list	ap
	)

kernel printf: formatted, synchronous output to SERIAL0.

Parameters

format	The format string. Not all standard format specifiers are supported by this implementation. See _doprnt() for a description of supported conversion specifications.
ap	Arguments matching those in the format string.

Returns

The number of characters written.

devcall uartControl	(	device *	devptr,
		int	func,
		long	arg1,
		long	arg2
	)

Control parameters to a UART.

Parameters

devptr	pointer to UART device
func	index of function to run (defined in uart.h)
arg1	first argument to called function
arg2	second argument to called function

Returns

SYSERR if control function not recognized; otherwise a control-function-dependent value.

devcall uartGetc

(

device *

devptr

)

Read a single character from a UART.

Parameters

devptr

Pointer to the device table entry for a UART.

Returns

On success, returns the character read as an unsigned char cast to an int. On read error, invalid device, or end-of file, returns SYSERR.

devcall uartInit

(

device *

devptr

)

Initialize a UART, including the entry in Xinu's UART table as well as the hardware itself.

Parameters

devptr

Pointer to the device table entry for the UART.

Returns

OK on success; SYSERR on failure.

devcall uartPutc	(	device *	devptr,
		char	ch
	)

Write a single character to a UART.

Parameters

devptr	Pointer to the device table entry for a UART.
ch	The character to write.

Returns

On success, returns the character written as an unsigned char cast to an int. On failure, returns SYSERR.

devcall uartRead	(	device *	devptr,
		void *	buf,
		uint	len
	)

Reads data from a UART.

Parameters

devptr	Pointer to the device table entry for a UART.
buf	Pointer to a buffer into which to place the read data.
len	Maximum number of bytes of data to read.

Returns

On success, returns the number of bytes read, which normally is len, but may be less than len if the UART has been set to non-blocking mode. Returns SYSERR on other error (currently, only if uartInit() has not yet been called).

void uartStat

(

ushort

uartnum

)

Prints information about the current status of a UART.

Parameters

uartnum

The minor number of the UART.

devcall uartWrite	(	device *	devptr,
		const void *	buf,
		uint	len
	)

Write a buffer of data to a UART.

Caveat: this operates asynchronously, so the data written may be held in an internal buffer and not yet actually written to the hardware. The UART driver's lower half (interrupt handler; see uartInterrupt()) is responsible for actually writing the data to the hardware. Exception: when the UART transmitter is idle, uartWrite() can directly write one byte to the hardware.

Parameters

devptr	Pointer to the device table entry for a UART.
buf	Pointer to the buffer of data to write.
len	Number of bytes to write.

Returns

On success, returns the number of bytes written, which normally is len, but may be less than len if the UART has been set to non-blocking mode. Returns ::SYSERR on other error (currently, only if uartInit() has not yet been called).

Variable Documentation

struct uart uarttab[NUART]

Global table of UART devices that are available in the current Embedded Xinu configuration.