.\" .\" Copyright (c) 2015 M. Warner Losh .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. The name of the author may not be used to endorse or promote products .\" derived from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .Dd July 20, 2015 .Dt OWN 9 .Os .Sh NAME .Nm own , .Nm own_send_command , .Nm own_command_wait , .Nm own_self_command , .Nm own_acquire_bus , .Nm own crc , .Nm own_release_bus , .Nm OWN_ACQUIRE_BUS , .Nm OWN_CRC , .Nm OWN_RELEASE_BUS , .Nm OWN_SEND_COMMAND .Nd Dallas Semiconductor 1-Wire Network and Transport Interface .Sh SYNOPSIS .In sys/bus.h .In dev/ow/own.h .Ft int .Fn own_send_command "device_t pdev" "struct ow_cmd *cmd" .Ft int .Fn own_command_wait "device_t pdev" "struct ow_cmd *cmd" .Ft int .Fn own_self_command "device_t pdev" "struct ow_cmd *cmd" "uint8_t xpt_cmd" .Ft int .Fn own_acquire_bus "device_t pdev" "int how" .Ft int .Fn own_release_bus "device_t pdev" .Ft int .Fn own_crc "device_t pdev" "uint8_t *buffer" "size_t len" .Ft int .Fn OWN_SEND_COMMAND "device_t ndev" "device_t pdev" "struct ow_cmd *cmd" .Ft int .Fn OWN_ACQUIRE_BUS "device_t ndev" "device_t pdev" "int how" .Ft void .Fn OWN_RELEASE_BUS "device_t ndev" "device_t pdev" .Ft uint8_t .Fn OWN_CRC "device_t ndev" "device_t pdev" "uint8_t *buffer" "size_t len" .Sh DESCRIPTION The .Nm interface defines three sets of functions for interacting with 1-Wire devices: sending commands, reserving the bus, and ensuring data integrity. Wrappers are provided for the raw .Nm OWN .Xr kobj 9 interfaces and should be used for improved safety over the .Xr kobj 9 ones. .Ss Bus Commands The 1-Wire bus defines different layers of access to the devices on the bus. The .Nm functions provide access to the network and transport layers. The network layer designates the next command as being either for all devices on the bus, or for a specific device. The network layer also specifies the speed used by the link layer. .Pp .Vt "struct ow_cmd" encapsulates network access, speed, and timing information. It specifies the commands to send and whether or not to read data. Its members are: .Bl -tag -width ".Va xxxx" .It Va flags Flags controlling the interpretation of the structure. These flags are defined in .In dev/ow/ow.h : .Bl -tag -width indent .It OW_FLAG_OVERDRIVE Send .Va xpt_cmd bytes and read .Va xpt_read bytes at overdrive speed. .It OW_FLAG_READ_BIT Interpret .Va xpt_read_len to be in bits to be read after .Va xpt_cmd rather than bytes. .El .It Va rom_cmd ROM command bytes to send. .It Va rom_len Number of ROM command bytes to send. .It Va rom_read_len Number of bytes to read after sending the ROM command. .It Va rom_read Buffer for bytes read after the ROM command. .It Va xpt_cmd Transport command to send. .It Va xpt_len Length of the transport command bytes to send. Specify 0 for no transport command. .It Va xpt_read_len Number of bytes to read after .Va xpt_cmd bytes are sent. If the .Dv OW_FLAG_READ_BIT bit is set in .Va flags , then it is the number of bits to read. Bits read are packed into bytes. .It Va xpt_read Buffer for data read. .El .Pp .Fn own_command_wait acquires the 1-Wire bus, waiting if necessary, sends the command, and then releases the bus. .Fn own_send_command sends the command without bus reservation. .Fa pdev is the client device (the presentation layer device) sending the command. The .Fa cmd argument describes the transaction to send to the 1-Wire bus. .Pp .Fn own_self_command fills in .Fa cmd with a MATCH_ROM ROM command, the ROM address of .Fa pdev and the .Fa xpt_cmd as a convenient way to create directed commands. .Ss Bus Reservation The 1-Wire system includes an advisory lock for the bus that presentation layer devices can use to coordinate access. Locking is purely advisory at this time. .Pp .Fn own_acquire_bus reserves the bus. It waits indefinitely if the .Fa how argument is .Dv OWN_WAIT and returns the error .Dv EWOULDBLOCK if passed .Dv OWN_DONTWAIT when the bus is owned by another client. .Pp .Fn own_release_bus releases the bus. .Ss Data Integrity .Fn own_crc computes the 1-Wire standard CRC function over the data passed in .Fa buffer and .Fa len and returns the result. .Ss Notes The 1-Wire standard (Maxim AN937) defines layers that are akin to ISO networking layers. The lowest relevant layer, the link layer, defines the polling windows and the timing of the signaling of different modes. The network layer is built on top of the link layer and is used to address devices in a unicast or multicast manner. The transport layer defines commands and responses from the devices. The presentation layer is composed of the device specific commands and actions used to control the specific 1-Wire devices on bus. .Pp These interfaces are implemented by the .Xr ow 4 device. Presentation layer devices (children of the newbus .Xr ow 4 device) should only call the functions described here. The functionality provided by the .Xr owc 4 device (specifically the .Xr owll 9 interface) should only be called by the .Xr ow 4 driver. .Sh SEE ALSO .Xr ow 4 , .Xr owc 4 , .Xr owll 9 .Pa https://pdfserv.maximintegrated.com/en/an/AN937.pdf .Sh LEGAL .Tn 1-Wire is a registered trademark of Maxim Integrated Products, Inc. .Sh HISTORY The .Nm driver first appeared in .Fx 11.0 . .Sh AUTHORS The .Nm device driver and this manual page were written by .An Warner Losh .