>> smb (4) ( FreeBSD man: Специальные файлы /dev/* )
BSD mandoc
NAME
smb
- SMB generic I/O device driver
SYNOPSIS
device smb
DESCRIPTION
The
smb
character device driver provides generic i/o to any
smbus(4)
instance.
In order to control SMB devices, use
/dev/smb?
with the ioctls described below.
Any of these ioctl commands takes a pointer to
Vt struct smbcmd
as its argument.
#include <sys/types.h>
struct smbcmd {
char cmd;
int count;
u_char slave;
union {
char byte;
short word;
char *byte_ptr;
short *word_ptr;
struct {
short sdata;
short *rdata;
} process;
} data;
};
The
Fa slave
field is always used, and provides the address of the
SMBus slave device to talk to.
Ioctl Ta Description
SMB_QUICK_WRITE Ta The
QuickWrite
command just issues the device address with write intent
to the bus, without transferring any data.
SMB_QUICK_READ Ta The
QuickRead
command just issues the device address with read intent
to the bus, without transferring any data.
SMB_SENDB Ta The
SendByte
command sends the byte provided in the
Fa cmd
field to the device.
SMB_RECVB Ta The
ReceiveByte
command reads a single byte from the device which will
be returned in the
Fa cmd
field.
SMB_WRITEB Ta The
WriteByte
command first sends the byte from the
Fa cmd
field to the device, followed by the byte given in
Fa data.byte .
SMB_WRITEW Ta The
WriteWord
command first sends the byte from the
Fa cmd
field to the device, followed by the word given in
Fa data.word .
Note that the SMBus byte-order is little-endian by definition.
SMB_READB Ta The
ReadByte
command first sends the byte from the
Fa cmd
field to the device, and then reads one byte of data from
the device.
The returned data will be stored in the location pointed to by
Fa data.byte_ptr .
SMB_READW Ta The
ReadWord
command first sends the byte from the
Fa cmd
field to the device, and then reads one word of data from
the device.
The returned data will be stored in the location pointed to by
Fa data.word_ptr .
SMB_PCALL Ta The
ProcedureCall
command first sends the byte from the
Fa cmd
field to the device, followed by the word provided in
Fa data.process.sdata .
It then reads one word of data from the device, and returns it
in the location pointed to by
Fa data.process.rdata .
SMB_BWRITE Ta The
BlockWrite
command first sends the byte from the
Fa cmd
field to the device, followed by
Fa count
bytes of data that are taken from the buffer pointed to by
Fa data.byte_ptr .
The SMBus specification mandates that no more than 32 bytes of
data can be transferred in a single block read or write command.
This value is available in the constant
SMB_MAXBLOCKSIZE
SMB_BREAD Ta The
BlockRead
command first sends the byte from the
Fa cmd
field to the device, and then reads
Fa count
bytes of data that from the device.
These data will be returned in the buffer pointed to by
Fa data.byte_ptr .
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:
Bq Er ENXIO
Device did not respond to selection.
Bq Er EBUSY
Device still in use.
Bq Er ENODEV
Operation not supported by device (not supposed to happen).
