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2 .\" Copyright (c) 2004, Joerg Wunsch
3 .\" Copyright (c) 2015, Michael Gmelin <freebsd@grem.de>
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34 .Nd SMB generic I/O device driver
40 character device driver provides generic i/o to any
43 In order to control SMB devices, use
45 with the ioctls described below.
46 Any of these ioctl commands takes a pointer to
50 #include <sys/types.h>
67 char *wbuf; /* use wdata if NULL */
69 char *rbuf; /* use rdata if NULL */
76 field is always used, and provides the address of the
77 SMBus slave device to talk to.
78 The slave address is specified in the seven most significant bits
79 .Pq i.e. Dq "left-justified" .
80 The least significant bit of the slave address must be zero.
82 .Bl -column ".Dv SMB_QUICK_WRITE" -compact
83 .It Em Ioctl Ta Em Description
85 .It Dv SMB_QUICK_WRITE Ta
88 command just issues the device address with write intent
89 to the bus, without transferring any data.
90 .It Dv SMB_QUICK_READ Ta
93 command just issues the device address with read intent
94 to the bus, without transferring any data.
98 command sends the byte provided in the
104 command reads a single byte from the device which will
111 command first sends the byte from the
113 field to the device, followed by the byte given in
118 command first sends the byte from the
120 field to the device, followed by the word given in
122 Note that the SMBus byte-order is little-endian by definition.
126 command first sends the byte from the
128 field to the device, and then reads one byte of data from
130 The returned data will be stored in
135 command first sends the byte from the
137 field to the device, and then reads one word of data from
139 The returned data will be stored in
144 command first sends the byte from the
146 field to the device, followed by the word provided in
148 It then reads one word of data from the device, and returns it
154 command first sends the byte from the
156 field to the device, followed by
158 bytes of data that are taken from the buffer pointed to by
160 The SMBus specification mandates that no more than 32 bytes of
161 data can be transferred in a single block read or write command,
164 is also used to access I2C devices, the limit has been increased
166 This value is available in the constant
167 .Dv SMB_MAXBLOCKSIZE .
171 command first sends the byte from the
173 field to the device, and then reads
175 bytes of data that from the device.
176 These data will be returned in the buffer pointed to by
181 command sends an SMB roll-up transaction with flags that also allow it to
182 be used for (mostly) I2C pass-through and with with 10-bit addresses.
183 This function can be used to roll up all of the above functions.
184 It first sends the byte from the
186 field to the device, followed by
188 bytes of data that are taken from the buffer pointed to by
192 bytes of data that from the device.
193 These data will be returned in the buffer pointed to by
196 The following flags are allowed in
199 .Bd -literal -compact
200 SMB_TRANS_NOSTOP Do not send STOP at end
201 SMB_TRANS_NOCMD Ignore cmd field (do not tx)
202 SMB_TRANS_NOCNT Do not tx or rx count field
203 SMB_TRANS_7BIT Change address mode to 7-bit
204 SMB_TRANS_10BIT Change address mode to 10-bit
212 system calls are not implemented by this driver.
216 commands can cause the following driver-specific errors:
219 Device did not respond to selection.
223 Operation not supported by device (not supposed to happen).
225 General argument error.
226 .It Bq Er EWOULDBLOCK
227 SMBus transaction timed out.
235 manual page first appeared in
239 manual page was written by
242 .An Michael Gmelin Aq freebsd@grem.de