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OWN(9) FreeBSD Kernel Developer's Manual OWN(9)
NAME
own, own_send_command, own_command_wait, own_self_command,
own_acquire_bus, own crc, own_release_bus, OWN_ACQUIRE_BUS, OWN_CRC,
OWN_RELEASE_BUS, OWN_SEND_COMMAND - Dallas Semiconductor 1-Wire Network
and Transport Interface
SYNOPSIS
#include <sys/bus.h>
#include <dev/ow/own.h>
int
own_send_command(device_t pdev, struct ow_cmd *cmd);
int
own_command_wait(device_t pdev, struct ow_cmd *cmd);
int
own_self_command(device_t pdev, struct ow_cmd *cmd, uint8_t xpt_cmd);
int
own_acquire_bus(device_t pdev, int how);
int
own_release_bus(device_t pdev);
int
own_crc(device_t pdev, uint8_t *buffer, size_t len);
int
OWN_SEND_COMMAND(device_t ndev, device_t pdev, struct ow_cmd *cmd);
int
OWN_ACQUIRE_BUS(device_t ndev, device_t pdev, int how);
void
OWN_RELEASE_BUS(device_t ndev, device_t pdev);
uint8_t
OWN_CRC(device_t ndev, device_t pdev, uint8_t *buffer, size_t len);
DESCRIPTION
The own 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 OWN kobj(9) interfaces and
should be used for improved safety over the kobj(9) ones.
Bus Commands
The 1-Wire bus defines different layers of access to the devices on the
bus. The own 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.
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:
OW_FLAG_READ_BIT
Interpret xpt_read_len to be in bits to be read after
xpt_cmd rather than bytes.
rom_cmd
ROM command bytes to send.
rom_len
Number of ROM command bytes to send.
rom_read_len
Number of bytes to read after sending the ROM command.
rom_read
Buffer for bytes read after the ROM command.
xpt_cmd
Transport command to send.
xpt_len
Length of the transport command bytes to send. Specify 0 for no
transport command.
xpt_read_len
Number of bytes to read after xpt_cmd bytes are sent. If the
OW_FLAG_READ_BIT bit is set in flags, then it is the number of bits
to read. Bits read are packed into bytes.
xpt_read
Buffer for data read.
own_command_wait() acquires the 1-Wire bus, waiting if necessary, sends
the command, and then releases the bus. own_send_command() sends the
command without bus reservation. pdev is the client device (the
presentation layer device) sending the command. The cmd argument
describes the transaction to send to the 1-Wire bus.
own_self_command() fills in cmd with a MATCH_ROM ROM command, the ROM
address of pdev and the xpt_cmd as a convenient way to create directed
commands.
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.
own_acquire_bus() reserves the bus. It waits indefinitely if the how
argument is OWN_WAIT and returns the error EWOULDBLOCK if passed
OWN_DONTWAIT when the bus is owned by another client.
own_release_bus() releases the bus.
Data Integrity
own_crc() computes the 1-Wire standard CRC function over the data passed
in buffer and len and returns the result.
Notes
The 1-Wire standard (Maxim AN937) defines layers that are akin to ISO
These interfaces are implemented by the ow(4) device. Presentation layer
devices (children of the newbus ow(4) device) should only call the
functions described here. The functionality provided by the owc(4)
device (specifically the owll(9) interface) should only be called by the
ow(4) driver.
SEE ALSO
ow(4), owc(4), owll(9)
https://pdfserv.maximintegrated.com/en/an/AN937.pdf
LEGAL
1-Wire is a registered trademark of Maxim Integrated Products, Inc.
HISTORY
The own driver first appeared in FreeBSD 11.0.
AUTHORS
The own device driver and this manual page were written by Warner Losh.
FreeBSD 14.0-RELEASE-p6 July 20, 2015 FreeBSD 14.0-RELEASE-p6