Linux is using 7 bit addressing while FreeBSD uses 8 bit addresses
internally, but i2c(8) uses 7 bit address.
This confused me when originally doing the code and I thought that
0x50 was the 8bit EDID address while it's the 7bit address and since
I did all my testing using this I didn't noticed the problem.
Reported by: avg
PR: 265920 (somewhat)
We need Giant as we run in a taskqueue_thread via linux_work.
This fix detaching amdgpu and i915kms.
Reviewed by: bz, hselasky, imp
Sponsored by: Beckhoff Automation GmbH & Co. KG
Differential Revision: https://reviews.freebsd.org/D35478
We need to detach the matching i2c adapter so look for the right one.
While here add some locks to protect multiple add/del at the same time.
Fixes: 1961a14a47 ("linuxkpi: Add i2c support")
Sponsored by: Beckhoff Automation GmbH & Co. KG
Add i2c support to linuxkpi. This is needed by drm-kmod.
For every i2c_adapter added by i2c_add_adapter we add a child to the
device named "lkpi_iic". This child handle the conversion between
Linux i2c_msgs to FreeBSD iic_msgs.
For every i2c_adapter added by i2c_bit_add_bus we add a child to the
device named "lkpi_iicbb". This child handle the conversion between
Linux i2c_msgs to FreeBSD iic_msgs.
With the help of iic(4), this expose the i2c controller to userspace
allowing a user to query DDC information from a monitor.
e.g.: i2c -f /dev/iic0 -a 0x28 -c 128 -d r
will query the standard EDID from the monitor if plugged.
The bitbang part (lkpi_iicbb) isn't tested at all for now as I don't have
compatible hardware (all my hardware have native i2c controller).
Tested on: Intel (SandyBridge, Skylake, ApolloLake)
Tested on: AMD (Picasso, Polaris (amd64 and arm64))
MFC after: 1 month
Reviewed by: hselasky
Sponsored by: Beckhoff Automation GmbH & Co. KG
Differential Revision: https://reviews.freebsd.org/D33053
