Merge branch 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6 (56b85f32) · Commits · 戴 / test

Documentation/ABI/testing/sysfs-tty

0 → 100644

+19 −0

Original line number	Diff line number	Diff line
		What: /sys/class/tty/console/active
		Date: Nov 2010
		Contact: Kay Sievers <kay.sievers@vrfy.org>
		Description:
		Shows the list of currently configured
		console devices, like 'tty1 ttyS0'.
		The last entry in the file is the active
		device connected to /dev/console.
		The file supports poll() to detect virtual
		console switches.

		What: /sys/class/tty/tty0/active
		Date: Nov 2010
		Contact: Kay Sievers <kay.sievers@vrfy.org>
		Description:
		Shows the currently active virtual console
		device, like 'tty1'.
		The file supports poll() to detect virtual
		console switches.

Documentation/filesystems/proc.txt

+24 −0

Original line number	Diff line number	Diff line
		@@ -1181,6 +1181,30 @@ Table 1-12: Files in /proc/fs/ext4/<devname>
		mb_groups details of multiblock allocator buddy cache of free blocks
		..............................................................................

		2.0 /proc/consoles
		------------------
		Shows registered system console lines.

		To see which character device lines are currently used for the system console
		/dev/console, you may simply look into the file /proc/consoles:

		> cat /proc/consoles
		tty0 -WU (ECp) 4:7
		ttyS0 -W- (Ep) 4:64

		The columns are:

		device name of the device
		operations R = can do read operations
		W = can do write operations
		U = can do unblank
		flags E = it is enabled
		C = it is prefered console
		B = it is primary boot console
		p = it is used for printk buffer
		b = it is not a TTY but a Braille device
		a = it is safe to use when cpu is offline
		major:minor major and minor number of the device separated by a colon

		------------------------------------------------------------------------------
		Summary

Documentation/serial/00-INDEX

+2 −0

Original line number	Diff line number	Diff line
		@@ -14,6 +14,8 @@ riscom8.txt
		- notes on using the RISCom/8 multi-port serial driver.
		rocket.txt
		- info on the Comtrol RocketPort multiport serial driver.
		serial-rs485.txt
		- info about RS485 structures and support in the kernel.
		specialix.txt
		- info on hardware/driver for specialix IO8+ multiport serial card.
		stallion.txt

Documentation/serial/serial-rs485.txt

0 → 100644

+120 −0

Original line number	Diff line number	Diff line
		RS485 SERIAL COMMUNICATIONS

		1. INTRODUCTION

		EIA-485, also known as TIA/EIA-485 or RS-485, is a standard defining the
		electrical characteristics of drivers and receivers for use in balanced
		digital multipoint systems.
		This standard is widely used for communications in industrial automation
		because it can be used effectively over long distances and in electrically
		noisy environments.

		2. HARDWARE-RELATED CONSIDERATIONS

		Some CPUs/UARTs (e.g., Atmel AT91 or 16C950 UART) contain a built-in
		half-duplex mode capable of automatically controlling line direction by
		toggling RTS or DTR signals. That can be used to control external
		half-duplex hardware like an RS485 transceiver or any RS232-connected
		half-duplex devices like some modems.

		For these microcontrollers, the Linux driver should be made capable of
		working in both modes, and proper ioctls (see later) should be made
		available at user-level to allow switching from one mode to the other, and
		vice versa.

		3. DATA STRUCTURES ALREADY AVAILABLE IN THE KERNEL

		The Linux kernel provides the serial_rs485 structure (see [1]) to handle
		RS485 communications. This data structure is used to set and configure RS485
		parameters in the platform data and in ioctls.

		Any driver for devices capable of working both as RS232 and RS485 should
		provide at least the following ioctls:

		- TIOCSRS485 (typically associated with number 0x542F). This ioctl is used
		to enable/disable RS485 mode from user-space

		- TIOCGRS485 (typically associated with number 0x542E). This ioctl is used
		to get RS485 mode from kernel-space (i.e., driver) to user-space.

		In other words, the serial driver should contain a code similar to the next
		one:

		static struct uart_ops atmel_pops = {
		/* ... */
		.ioctl = handle_ioctl,
		};

		static int handle_ioctl(struct uart_port *port,
		unsigned int cmd,
		unsigned long arg)
		{
		struct serial_rs485 rs485conf;

		switch (cmd) {
		case TIOCSRS485:
		if (copy_from_user(&rs485conf,
		(struct serial_rs485 *) arg,
		sizeof(rs485conf)))
		return -EFAULT;

		/* ... */
		break;

		case TIOCGRS485:
		if (copy_to_user((struct serial_rs485 *) arg,
		...,
		sizeof(rs485conf)))
		return -EFAULT;
		/* ... */
		break;

		/* ... */
		}
		}


		4. USAGE FROM USER-LEVEL

		From user-level, RS485 configuration can be get/set using the previous
		ioctls. For instance, to set RS485 you can use the following code:

		#include <linux/serial.h>

		/* Driver-specific ioctls: */
		#define TIOCGRS485 0x542E
		#define TIOCSRS485 0x542F

		/* Open your specific device (e.g., /dev/mydevice): */
		int fd = open ("/dev/mydevice", O_RDWR);
		if (fd < 0) {
		/* Error handling. See errno. */
		}

		struct serial_rs485 rs485conf;

		/* Set RS485 mode: */
		rs485conf.flags \|= SER_RS485_ENABLED;

		/* Set rts delay before send, if needed: */
		rs485conf.flags \|= SER_RS485_RTS_BEFORE_SEND;
		rs485conf.delay_rts_before_send = ...;

		/* Set rts delay after send, if needed: */
		rs485conf.flags \|= SER_RS485_RTS_AFTER_SEND;
		rs485conf.delay_rts_after_send = ...;

		if (ioctl (fd, TIOCSRS485, &rs485conf) < 0) {
		/* Error handling. See errno. */
		}

		/* Use read() and write() syscalls here... */

		/* Close the device when finished: */
		if (close (fd) < 0) {
		/* Error handling. See errno. */
		}

		5. REFERENCES

		[1] include/linux/serial.h

arch/alpha/include/asm/ioctls.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -92,6 +92,7 @@
		#define TIOCGSID 0x5429 /* Return the session ID of FD */
		#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux device) */
		#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
		#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get primary device node of /dev/console */
		#define TIOCSIG _IOW('T',0x36, int) /* Generate signal on Pty slave */

		#define TIOCSERCONFIG 0x5453

Admin message