A driver for the DS28E17 1-Wire to I2C bridge chip.

This chip acts like a 1-Wire slave device and provides a iic(4) master
at the end of the 1-Wire bus. More or less it is the polar opposite
of the DS2482 [ds2482ow(4)] chip.

This device couples well with ds2482ow(4) and can be used to provide a
I2C bus at very great lengths from the controlling computer.

All features of the chip are supported, except for 1-Wire overdrive
support, which requires more work from the onewire(4) infrastructure.

The chip does not support Read without Stop. Attempts to do this will
get turned into a Read with Stop and one will have to hope for the
best. The chip also does not support zero length I2C reads or zero
length I2C writes. This has the side effect of making the default
mode, a zero length I2C write, for i2scan(8) return false positives.
The alternative mode that i2cscan(8) can use, the single byte read,
should work as expected.

The chip has automatic support for end devices that do I2C clock
stretching.

It was noticed that this chip does not work with the gpioow(4) driver.
That might be an interesting thing to debug if one has a good logic
analyzer on hand. While the presence pulse is detected, the gpioow(4)
driver is not able to complete the initial ROM enumeration. The
DS28E17 works flawlessly when driven by a DS2482 [ds2482ow(4)] driver
chip. Poke me if you want any more details.

The chip is pretty inexpensive and only requires a single cap to get
it hooked up. However, the package it comes in is only a 16-QFN
package, so it could provide to be hard to solider onto a board for
some. There are side tabs, so it was possible with a very small iron
and lots of flux. There is a slightly expensive breakout board sold
by Mikroe that probably works well -> https://www.mikroe.com/1-wire-i2c-click

branches: 1.5.26;
defflag ONEWIRE_DEBUG

add 'driver' for DS2430A EEPROMs which simply dumps the chip's contents and
status register

branches: 1.3.2; 1.3.4; 1.3.8; 1.3.12; 1.3.18; 1.3.162; 1.3.174;
Fix some RCS IDs, and the comments including them.

branches: 1.2.2;
Add NetBSD RCSIDs

Dallas Semiconductor 1-Wire bus support, from OpenBSD. Currently includes
gpioow(4), attaching a bit-banging driver via a GPIO pin. Also,
owtemp(4) which supports some of the 1-Wire temperature sensors, including
the DS18b20 and DS1920 - temperatures are returned via the envsys(4)
framework.

Original drivers by Alexander Yurchenko (grange@openbsd), with envsys(4)
support and a fix to the 1-wire search algorithm (for discovering
devices on the bus) by me.

As discussed on tech-kern earlier this week.