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smb(4)

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 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 slave field is always used, and provides the address of the SMBus
     slave device to talk to.

     Ioctl		Description

     SMB_QUICK_WRITE	The QuickWrite command just issues the device address
			with write intent to the bus, without transferring any
			data.
     SMB_QUICK_READ	The QuickRead command just issues the device address
			with read intent to the bus, without transferring any
			data.
     SMB_SENDB		The SendByte command sends the byte provided in the
			cmd field to the device.
     SMB_RECVB		The ReceiveByte command reads a single byte from the
			device which will be returned in the cmd field.
     SMB_WRITEB 	The WriteByte command first sends the byte from the
			cmd field to the device, followed by the byte given in
			data.byte.
     SMB_WRITEW 	The WriteWord command first sends the byte from the
			cmd field to the device, followed by the word given in
			data.word.  Note that the SMBus byte-order is little-
			endian by definition.
     SMB_READB		The ReadByte command first sends the byte from the cmd
			field to the device, and then reads one byte of data
			from the device.  The returned data will be stored in
			of data from the device, and returns it in the loca-
			tion pointed to by data.process.rdata.
     SMB_BWRITE 	The BlockWrite command first sends the byte from the
			cmd field to the device, followed by count bytes of
			data that are taken from the buffer pointed to by
			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		The BlockRead command first sends the byte from the
			cmd field to the device, and then reads count bytes of
			data that from the device.  These data will be
			returned in the buffer pointed to by data.byte_ptr.

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

ERRORS

     The ioctl 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.

SEE ALSO

     ioctl(2), smbus(4)

HISTORY

     The smb manual page first appeared in FreeBSD 3.0.

AUTHORS

     This manual page was written by Nicolas Souchu.

FreeBSD 5.4		       October 25, 1998 		   FreeBSD 5.4

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