iicbb: Fix pause_sbt() arguments order

It should make pause interval less strict.

While there, add cpu_spinwait() into a tight spin wait loop to burn
less power and let other SMT thread work more.

iicbb: Fix pause_sbt() arguments order

It should make pause interval less strict.

While there, add cpu_spinwait() into a tight spin wait loop to burn
less power and let other SMT thread work more.

MFC after: 1 month

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sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

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Remove unused iicbus_devclass.

Remove unused iicbb_devclass.

move defintion of hw.i2c sysctl node from iicbb to iicbus

MFC after: 2 weeks

iicbb: rebuild the bit-banging algorithms using different primitives

I2C_SET was quite inflexible, it used too long delays as well as some
unnecessary delays. The new building blocks are iicbb_cloc

iicbb: rebuild the bit-banging algorithms using different primitives

I2C_SET was quite inflexible, it used too long delays as well as some
unnecessary delays. The new building blocks are iicbb_clockin and
iicbb_clockout. The former sets SDA and starts the high period of SCL,
the latter executes the low period of SCL. What happens during the high
phase depends on the operation. For writes we just hold both lines, for
reads we poll SDA. S, Sr and P change SDA in the middle of the high
period.

Also, the calculation of udelay has been updated, so that the resulting
period more closely corresponds the requested bus frequency. There is a
new knob, io_delay, that allows to further adjust udelay based on the
estimated latency of pin toggling operations.

Finally, I slightly changed debug tracing and added error indicators to
it. The debug prints are compiled in but disabled by default. This can
be of use if there is any fallout from this change.

Some ideas for further improvements:
- add a function for sub-microsecond delays (e.g., in units of 1/10th of
a microsecond) and use it for more precise timing of short delays;
- account for the actual time spent in the pin I/O.

Some sample debug output with the new code follows.

Reading temperature and humidity from HTU21 in the bus hold mode:
<<w80+ we3+ <w81+ .....r6d+ rac+ r94- >>
<<w80+ we5+ <w81+ .............r47+ re2+ r84- >>
where '<<' is S, '<' is Sr, '>>' is P, '.' is one millisecond of clock
stretching by the slave.

Reading temperature and humidity in the no-hold mode:
<<w80+ wf3+ >>
<<w81- >>
<<w81+ r6d+ r54+ raf- >>
<<w80+ wf5+ >>
<<w81- >>
<<w81+ r48+ r4e+ r9c- >>
where '+' is Ack and '-' is NoAck.
We see that first read attempts are not acknowledged.

MFC after: 4 weeks
Differential Revision: https://reviews.freebsd.org/D22206

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iicbb: allow longer SCL low timeout and other improvements

First, SCL low timeout is set to 25 milliseconds by default as opposed
to 1 millisecond before. The new value is based on the SMBus
specif

iicbb: allow longer SCL low timeout and other improvements

First, SCL low timeout is set to 25 milliseconds by default as opposed
to 1 millisecond before. The new value is based on the SMBus
specification. The timeout can be changed on a per bus basis using
dev.iicbb.N.scl_low_timeout sysctl.

The driver uses DELAY to wait for high SCL up to 1 millisecond, then it
switches to pause_sbt(SBT_1MS) for the rest of the timeout.

While here I made a number of other changes. 'udelay' that's used for
timing clock and data signals is now calculated based on the requested
bus frequency (dev.iicbus.N.frequency) instead of being hardcoded to 10
microseconds. The calculations are done in such a fashion that the
default bus frequency of 100000 is converted to udelay of 10 us. This
is for backward compatibility. The actual frequency will be less than a
quarter (I think) of the requested frequency.

Also, I added detection of stuck low SCL in a few places. Previously,
the code would just carry on after the SCL low timeout and that might
potentially lead to misinterpreted bits.

Finally, I fixed several style issues near the code that I changed.
Many more are still remaining.

Tested by accessing HTU21 temperature and humidity sensor in this setup:
superio0: <Nuvoton NCT5104D/NCT6102D/NCT6106D (rev. B+)> at port 0x2e-0x2f on isa0
gpio1: <Nuvoton GPIO controller> at GPIO ldn 0x07 on superio0
pcib0: allocated type 4 (0x220-0x226) for rid 0 of gpio1
gpiobus1: <GPIO bus> on gpio1
gpioiic0: <GPIO I2C bit-banging driver> at pins 14-15 on gpiobus1
gpioiic0: SCL pin: 14, SDA pin: 15
iicbb0: <I2C bit-banging driver> on gpioiic0
iicbus0: <Philips I2C bus> on iicbb0 master-only
iic0: <I2C generic I/O> on iicbus0

Discussed with: ian, imp
MFC after: 3 weeks
Differential Revision: https://reviews.freebsd.org/D22109

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sys/dev: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error

sys/dev: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

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iicbus: Use device_delete_children() instead of explicit child removal

If the bus is detached and deleted by a call to device_delete_child() or
device_delete_children() on a device higher in the tre

iicbus: Use device_delete_children() instead of explicit child removal

If the bus is detached and deleted by a call to device_delete_child() or
device_delete_children() on a device higher in the tree, I²C children
were already detached and deleted. So the device_t pointer stored in sc
points to freed memory: we must not try to delete it again.

By using device_delete_children(), we let subr_bus.c figure out if there
are children to take care of.

While here, make sure iicbus_detach() and iicoc_detach() call
device_delete_children() too, to be safe.

Reviewed by: jhb, imp
Approved by: jhb, imp
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D3926

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Allow the use of OFW I2C bus together with iicbb(4) on OFW-based systems.

This change makes ofw_iicbus attach to iicbb(4) controllers in addition to
the already supported i2c host bridges (iichb).

Allow the use of OFW I2C bus together with iicbb(4) on OFW-based systems.

This change makes ofw_iicbus attach to iicbb(4) controllers in addition to
the already supported i2c host bridges (iichb).

On iicbb(4) allow the direct access of the OFW parent node by its children,
so they can be directly attached to iicbb(4) node on the DTS without the
need of describing the i2c bus.

Approved by: adrian (mentor, implicit)

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Provide pre/post transfer method callbacks for icbbb
clients.

These are helful when making certain drivers work on both Linux
and FreeBSD without changing the code flow too much.

Reviewed by: kib,

Provide pre/post transfer method callbacks for icbbb
clients.

These are helful when making certain drivers work on both Linux
and FreeBSD without changing the code flow too much.

Reviewed by: kib, wlosh
MFC after: 1 month

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IIC bitbang changes - prepare to make the bit delay configurable; debug print changes.

* Right now the delay is hard coded at 10uS. This is a bit long when doing lots
of periodic i2c transactions.

IIC bitbang changes - prepare to make the bit delay configurable; debug print changes.

* Right now the delay is hard coded at 10uS. This is a bit long when doing lots
of periodic i2c transactions. So create a 'udelay' parameter and initialise it
to 10. This can be tuned later.

* Add a newline after a transaction finishes, so the debugging output isn't so
horrible.

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Fix iicbus_intr, iicbus_write and device_read_ivar prototypes...

Add locking to the various iicbus(4) bridge drivers:
- Just grab Giant in the ixp425_iic(4) driver since this driver uses
a shared address/data register window pair to access the actual
I2C regis

Add locking to the various iicbus(4) bridge drivers:
- Just grab Giant in the ixp425_iic(4) driver since this driver uses
a shared address/data register window pair to access the actual
I2C registers. None of the other ixp425 drivers lock access to these
shared address/data registers yet and that would need to be done before
this could use any meaningful locking.
- Add locking to the interrupt handler and 'iicbus_reset' methods of the
at91_twi(4) driver.
- Add locking to the pcf(4) driver. Other pcf(4) fixes include:
- Don't needlessly zero the softc.
- Use bus_foo rather than bus_space_foo and remove bus space tag and
handle from softc.
- The lpbb(4) driver just grabs Giant for now. This will be refined later
when ppbus(4) is locked.
- As was done with smbus earlier, move the DRIVER_MODULE() lines to match
the bus driver (either iicbus or iicbb) to the bridge driver into the
bridge drivers.

Tested by: sam (arm/ixp425)

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MFp4: Make iicbus_trasnfer_gen suitable for bridge drivers. Use it in the
bitbang bridge.

More properly cleanup the iicbus child when deleting it.

These are from patches by John Wehle, but the commentary has been
updated by me.

Obtained from: ports/multimedia/pvr250, indirectly

Reference Hauppage's cxm_iic bit-bang device here.
Add a note that suggests a cleanup.

Note: This patch was derived based on looking at the pvrxxx/pvr250
ports' Makefiles only, and may be incomplete

Reference Hauppage's cxm_iic bit-bang device here.
Add a note that suggests a cleanup.

Note: This patch was derived based on looking at the pvrxxx/pvr250
ports' Makefiles only, and may be incomplete. It is not derived from
anything I saw from Hauppage.

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MFp4: Add ixpiic bit-bang driver.

Submitted by: sam@

Minor style(9) treatment to make things a little more consistant
within iicbus code.

newbus will zero softc, so no need to duplicate the zeroing here.
Plus a minor formatting nit in nearby code.

Use __FBSDID().
Also some minor style cleanups.

make iicbb_devclass and iicbb_driver globally visible. This will let
drivers that implemnt the i2c bit banging bus interface not have to
recompile iicbb in order to add an attachment for it.

This w

make iicbb_devclass and iicbb_driver globally visible. This will let
drivers that implemnt the i2c bit banging bus interface not have to
recompile iicbb in order to add an attachment for it.

This will mean the bktr and other definitions can go back to their
respective drivers.

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Major rework of the iicbus/smbus framework:

- VIA chipset SMBus controllers added
- alpm driver updated
- Support for dynamic modules added
- bktr FreeBSD smbus updated but not tested
- cleanup

Remove unneeded #include <machine/clock.h>