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
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.
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
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)
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
* 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.
- 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)
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.
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.
- device_print_child() either lets the BUS_PRINT_CHILD
method produce the entire device announcement message or
it prints "foo0: not found\n"
Alter sys/kern/subr_bus.c:bus_generic_print_child() to take on
the previous behavior of device_print_child() (printing the
"foo0: <FooDevice 1.1>" bit of the announce message.)
Provide bus_print_child_header() and bus_print_child_footer()
to actually print the output for bus_generic_print_child().
These functions should be used whenever possible (unless you can
just use bus_generic_print_child())
The BUS_PRINT_CHILD method now returns int instead of void.
Modify everything else that defines or uses a BUS_PRINT_CHILD
method to comply with the above changes.
- Devices are 'on' a bus, not 'at' it.
- If a custom BUS_PRINT_CHILD method does the same thing
as bus_generic_print_child(), use bus_generic_print_child()
- Use device_get_nameunit() instead of both
device_get_name() and device_get_unit()
- All BUS_PRINT_CHILD methods return the number of
characters output.
Reviewed by: dfr, peter
