smb(4) on freebsd

NAME

smb – System Management Bus (SMBus) generic I/O device driver

SYNOPSIS

device smb

DESCRIPTION

The smb character device driver provides generic I/O to any smbus(4) instance. To control SMB devices, use /dev/smb? with the ioctls described below. Any of these ioctl commands takes a pointer to struct smbcmd as its argument.

#include <sys/types.h>
struct smbcmd {
	u_char cmd;
	u_char reserved;
	u_short op;
	union {
		char    byte;
		char    buf[2];
		short   word;
	} wdata;
	union {
		char    byte;
		char    buf[2];
		short   word;
	} rdata;
	int  slave;
	char *wbuf;     /* use wdata if NULL */
	int  wcount;
	char *rbuf;     /* use rdata if NULL */
	int  rcount;
};

The slave field is always used, and provides the address of the SMBus slave device. The slave address is specified in the seven most significant bits (i.e., “left-justified”). The least significant bit of the slave address must be zero.

Ioctl	Description
SMB_QUICK_WRITE
SMB_QUICK_READ
SMB_SENDB
SMB_RECVB
SMB_WRITEB
SMB_WRITEW
SMB_READB
SMB_READW
SMB_PCALL
SMB_BWRITE
SMB_BREAD

The read(2) and write(2) system calls are not implemented by this driver.

ERRORS

The ioctl(2) commands can cause the following driver-specific errors:

[ENXIO]: Device did not respond to selection.
[EBUSY]: Device still in use.
[ENODEV]: Operation not supported by device (not supposed to happen).
[EINVAL]: General argument error.
[EWOULDBLOCK]: SMBus transaction timed out.

HISTORY

The smb manual page first appeared in FreeBSD 3.0.

AUTHORS

This manual page was written by Nicolas Souchu and extended by Michael Gmelin ⟨[email protected]⟩.

smb(4)