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Now that I learned about how all this is working together, quickly

Browse Source 
document it for anyone else who might be interested in it.

MFC after:	2 weeks
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Joerg Wunsch 2004-05-17 20:17:39 +00:00
parent 2526dc2b61
commit 7d2d5f8049
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162
share/man/man4/smb.4
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@ -1,4 +1,5 @@
.\" Copyright (c) 1998, Nicolas Souchu
.\" Copyright (c) 2004, Joerg Wunsch
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
@ -38,26 +39,157 @@ The
character device driver provides generic i/o to any
.Xr smbus 4
instance.
In order to control SMB devices, use /dev/smb? with the
following ioctls:
In order to control SMB devices, use
.Pa /dev/smb Ns Em ?
with the ioctls described below.
Any of these ioctl commands takes a pointer to
.Vt struct smbcmd
as its argument.
.Pp
.Bl -column "System Management Bus ioctls" -compact
.Bd -literal
#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;
};
.Ed
.Pp
The
.Fa slave
field is always used, and provides the address of the
SMBus slave device to talk to.
.Pp
.Bl -column ".Sy SMB_QUICK_WRITE" -compact
.It Em Ioctl Ta Em Description
.It Sy SMB_QUICK_WRITE Ta "QuickWrite command"
.It Sy SMB_QUICK_READ Ta "QuickRead command"
.It Sy SMB_SENDB Ta "SendByte command"
.It Sy SMB_RECVB Ta "ReceiveByte command"
.It Sy SMB_WRITEB Ta "WriteByte command"
.It Sy SMB_WRITEW Ta "WriteWord command"
.It Sy SMB_READB Ta "ReadByte command"
.It Sy SMB_READW Ta "ReadWord command"
.It Sy SMB_PCALL Ta "ProcedureCall command"
.It Sy SMB_BWRITE Ta "BlockWrite command"
.It Sy SMB_BREAD Ta "BlockRead command"
.Pp
.It Sy SMB_QUICK_WRITE Ta
The
.Em QuickWrite
command just issues the device address with write intent
to the bus, without transferring any data.
.It Sy SMB_QUICK_READ Ta
The
.Em QuickRead
command just issues the device address with read intent
to the bus, without transferring any data.
.It Sy SMB_SENDB Ta
The
.Em SendByte
command sends the byte provided in the
.Fa cmd
field to the device.
.It Sy SMB_RECVB Ta
The
.Em ReceiveByte
command reads a single byte from the device which will
be returned in the
.Fa cmd
field.
.It Sy SMB_WRITEB Ta
The
.Em WriteByte
command first sends the byte from the
.Fa cmd
field to the device, followed by the byte given in
.Fa data.byte .
.It Sy SMB_WRITEW Ta
The
.Em 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.
.It Sy SMB_READB Ta
The
.Em 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 .
.It Sy SMB_READW Ta
The
.Em 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 .
.It Sy SMB_PCALL Ta
The
.Em 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 .
.It Sy SMB_BWRITE Ta
The
.Em 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
.Dv SMB_MAXBLOCKSIZE .
.It Sy SMB_BREAD Ta
The
.Em 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 .
.El
.Pp
Using the write routine is equivalent to a SMB_WRITEW ioctl.
The
.Xr read 2
and
.Xr write 2
system calls are not implemented by this driver.
.Sh ERRORS
The
.Xr ioctl
commands can cause the following driver-specific errors:
.Bl -tag -width Er
.It Bq Er ENXIO
Device did not respond to selection.
.It Bq Er EBUSY
Device still in use.
.It Bq Er ENODEV
Operation not supported by device (not supposed to happen).
.It Bq Er EINVAL
General argument error.
.It Bq Er EWOULDBLOCK
SMBus transaction timed out.
.El
.Sh SEE ALSO
.Xr ioctl 2 ,
.Xr smbus 4
.Sh HISTORY
The