I had previously sent this to freebsd-net, but I'm told phrabricator is a better place for it. Copy and pasting from: https://lists.freebsd.org/pipermail/freebsd-net/2021-April/058173.html :

In D28521#638841, @james.wright_digital-chaos.com wrote:

Thanks! Would you be able to commit it for me?

In D28521#638470, @wulf wrote:

LGTM

In D28521#638399, @tomek_cedro.info wrote:

Is device supported by LibINPUT or IICHID? If so why not control it with "Narual Scroll" in /usr/local/share/X11/xorg.conf.d/40-libinput.conf :

wsp(4) still does not support evdev, so no touchpad libinput options can be applied to it.

LGTM

Hello world :-)

wulf@ Can you please have a look?

Done in https://reviews.freebsd.org/D25969

I think you approach may work for the mixer case, assuming no IOCTLs are sleeping. Please make sure that destroy_dev() will flush all pending system calls.

This is only mixer unplug fix.

In D16698#568211, @marc.priggemeyer_gmail.com wrote:

Are you having issues with sysutils/iichid or wulf's respository? He fixed serious issues and provided a HID layer that you should stick to.

In D16698#568171, @KOT_MATPOCKuH.Ru wrote:

I'm using patches from this review for last two years.
Please apply this patch to FreeBSD base code.

I'm using patches from this review for last two years.
Please apply this patch to FreeBSD base code.

Ah, on t2.micro I see warnings about fdc (but not about ppc). Normally I aim to minimize the difference between EC2 and "stock" FreeBSD, but I guess there's no harm in making this change even if it only affects older instance types.

In D18482#562033, @cperciva wrote:

Which instance type are you seeing this on? I haven't been able to reproduce it.

Which instance type are you seeing this on? I haven't been able to reproduce it.

@cperciva I think this patch is good, can you check it? Thanks!

No longer working on this. Someone else can take it up.

I don't know if comments to this review are still relevant, but I'd like to report that this driver built on recent 12.1-STABLE can work fine after resume. To enable suspend/resume support the module acpi_iichid has to be unloaded and loaded again which can be done for instance with the help of rc.{suspend,resume} scripts.

In D16698#478901, @marc.priggemeyer_gmail.com wrote:

Thanks for the remarks. I'd suggest to stop riding a dead horse and make the switch altogether.

This driver still has some advantages over mine. It supports 12.0-release, sysmouse(8) protocol and it does not require ig4 patching. So, I would prefer it for non-HID trackpads like some Synaptics models. Al least for now.

Thanks for the remarks. I'd suggest to stop riding a dead horse and make the switch altogether. It has been pointed out previously that the separation of ACPI and HID over I2C code like it was done here, especially the interrupt handling, was ill-conceived.
Abstraction of HID code was initially considered, but not implemented on my part. Since wulf has already done these things and even has the multitouch part working, switching over is the most sensible thing. This code here was intended to be a first draft and has served its purpose.

In D16698#478805, @greg_unrelenting.technology wrote:

In D16698#478767, @imp wrote:

So with the suggested changes, I'm not able to get very far with the patches in this review. With wulf's code I'm able to get the device probed. With this code, I see the following

Is this code still really considered? wulf's repo is currently actively developed (now even includes the long-awaited and very necessary "HID bus" abstraction), this was last updated in August.

data point: I'm using wulf's code on my Pixelbook, multi-touch works great for both the touchpad and touchscreen.

In D16698#478767, @imp wrote:

So with the suggested changes, I'm not able to get very far with the patches in this review. With wulf's code I'm able to get the device probed. With this code, I see the following

So with the suggested changes, I'm not able to get very far with the patches in this review. With wulf's code I'm able to get the device probed. With this code, I see the following:

kernel trap 22 with interrupts disabled
panic: spin locks can only use msleep_spin
cpuid = 7 time = 1569790352
KDB: stack backtrace:
#0 0xffffffff805da3fd at kdb_backtrace+0x6d
#1 0xffffffff80594fed at vpanic+0x19d
#2 0xffffffff80594e43 at panic+0x43
#3 0xffffffff8057df32 at unlock_spin+0x12
#4 0xffffffff8053f577 at _cv_wait_sig+0x127
#5 0xffffffff81d1dace at iichid_read+0x8e
#6 0xffffffff804b690a at devfs_read_f+0xda
#7 0xffffffff805f4752 at kern_readv+0x92
#8 0xffffffff805f46b4 at sys_read+0x84
#9 0xffffffff808451d8 at amd64_syscall+0x218
#10 0xffffffff80821270 at fast_syscall_common+0x101

Panic on kldload acpi_iichid in iichid_read()->cv_wait_sig().
FreeBSD 12.1 amd64 @ Asus 505z

I built this on -current and got an insta-panic when trying to lock a null spin lock in attach...

In D16698#464917, @imp wrote:

We really have three problems that we need to solve:

(1) iichid
(2) how to get the acpi stuff to automatically add iichid devices

iichid device is a child of acpi bus also, so it can be rephrased as "how to get the acpi stuff to automatically add acpi device with given CID"

(3) How to cope with resume and resets not being quite right for the ig4.

It is not clear which reset is mentioned:

1. IG4 controller reset (set designware specific parameters like timing counters and so on)
2. iicbus reset - FIFO flushing, setting of symbol speed and slave address
3. I2C hid device reset - performed with special I2C command

If it is mentioned in context of @johalun suspend/resume patch, then most probably it misses iicbus reset as it is performed by ig4 driver in a lazy way at a start of next xfer. sc->slave_valid bool variable should be reset to trigger it and I do not see that in @johalun resume method.

Would we make better progress with we split those three issues up into their own reviews?

In D16698#461247, @wulf wrote:

Hi @marc.priggemeyer_gmail.com,

I wrote iicbus(4) extension which performs ACPI-based enumeration of I2C devices connected to a controller. It is not limited to HID devices and fires at iicbus attach stage.

The extension walks through ACPI children of I2C controller and for each device found it:

1. Creates iicbus child device
2. Adds I2C address to ivars
3. Adds ACPI-handle to iicbus-child ivars, so you can evaluate acpi_get_handle(dev); on iicbus child
4. Copies all newbus resources from corresponding ACPIbus-hosted device to I2Cbus-hosted one.

It effectively makes a copy of existing ACPI device on top of I2C bus.
It should also fix ig4 bug that brokes allocation of interrupts on ig4 children (Only partially tested yet, I have access only to GPIO devices now)

I think using of this extension should eliminate nasty ACPI<->I2C devices interaction that is found in the patch from current review.
iicbus(4) extension support in my driver (for reference): https://github.com/wulf7/iichid/commit/6f5c3d3eb008848ab9d18e1dcf8fd35ca80e517e

Patch could be found here: https://people.freebsd.org/~wulf/acpi_iicbus.patch

I wrote iicbus(4) extension which performs ACPI-based enumeration of I2C devices connected to a controller. It is not limited to HID devices and fires at iicbus attach stage.

In D16698#457967, @wulf wrote:

Could you send me your DSDT table with email? It is too big to be posted here. It can be obtained with

# acpidump -dt

Sure, done.

In D16698#457886, @nikola.lecic_anthesphoria.net wrote:

However, loading iichid.ko doesn't go well:

Jul 29 03:00:32 thorium kernel: acpi_iichid0: <HID over I2C (ACPI)> on acpi0
Jul 29 03:00:32 thorium kernel: imt0:   ACPI Hardware ID  : ELAN1200
Jul 29 03:00:32 thorium kernel: imt0:   IICbus addr       : 0x15
Jul 29 03:00:32 thorium kernel: imt0:   HID descriptor reg: 0x01
Jul 29 03:00:32 thorium kernel: imt0: could not retrieve HID descriptor from the device: 3

try to replace 'IG4_CTL_SPEED_STD' string in /usr/src/sys/dev/ichiic/ig4_iic.c file with digit '6' than rebuild and reload ig4.ko .

In D16698#457884, @nikola.lecic_anthesphoria.net wrote:

In D16698#457883, @wulf wrote:

In D16698#457882, @nikola.lecic_anthesphoria.net wrote:

Yes, it still prints.

Ok. than uncomment pair of debugging printfs in iichid_event_task(). They lie several lines below iichid_intr() sub.
If you get one line with hex data per "something", post it here

If you mean these lines:

device_printf(sc->dev, "no data received\n");

and

DPRINTF(sc, "%*D\n", actual, sc->ibuf, " ");

then I get just this (a single touch):

Jul 29 02:01:08 thorium kernel: something
Jul 29 02:01:08 thorium syslogd: last message repeated 2 times
Jul 29 02:01:08 thorium kernel: imt0: no data received
Jul 29 02:01:08 thorium kernel: something
Jul 29 02:01:08 thorium syslogd: last message repeated 4 times
Jul 29 02:01:08 thorium kernel: imt0: no data received
Jul 29 02:01:08 thorium syslogd: last message repeated 1 times
Jul 29 02:01:08 thorium kernel: something
Jul 29 02:01:08 thorium syslogd: last message repeated 3 times
Jul 29 02:01:08 thorium kernel: imt0: no data received
Jul 29 02:01:08 thorium kernel: something
Jul 29 02:01:08 thorium syslogd: last message repeated 2 times
Jul 29 02:01:08 thorium kernel: imt0: no data received
Jul 29 02:01:08 thorium syslogd: last message repeated 1 times
Jul 29 02:01:08 thorium kernel: something
Jul 29 02:01:08 thorium syslogd: last message repeated 5 times
Jul 29 02:01:08 thorium kernel: imt0: no data received
Jul 29 02:01:08 thorium kernel: something
Jul 29 02:01:08 thorium syslogd: last message repeated 3 times
Jul 29 02:01:08 thorium kernel: imt0: no data received

In D16698#457883, @wulf wrote:

In D16698#457882, @nikola.lecic_anthesphoria.net wrote:

Yes, it still prints.

Ok. than uncomment pair of debugging printfs in iichid_event_task(). They lie several lines below iichid_intr() sub.
If you get one line with hex data per "something", post it here

In D16698#457882, @nikola.lecic_anthesphoria.net wrote:

Yes, it still prints.

In D16698#457878, @wulf wrote:

In D16698#457877, @nikola.lecic_anthesphoria.net wrote:

In D16698#457872, @wulf wrote:

In D16698#457858, @nikola.lecic_anthesphoria.net wrote:

In D16698#457847, @wulf wrote:

then comment out imt_set_input_mode() call in imt_attach() subroutine (imt.c) and insert printf("something\n"); into iichid_intr() sub (iichid.c)
If it print something on the console when you touching trackpad surface?

Yes! :) It prints "something".

It should print continuously if you'd move your finger

In D16698#457877, @nikola.lecic_anthesphoria.net wrote:

In D16698#457872, @wulf wrote:

In D16698#457858, @nikola.lecic_anthesphoria.net wrote:

In D16698#457847, @wulf wrote:

then comment out imt_set_input_mode() call in imt_attach() subroutine (imt.c) and insert printf("something\n"); into iichid_intr() sub (iichid.c)
If it print something on the console when you touching trackpad surface?

Yes! :) It prints "something".

In D16698#457872, @wulf wrote:

In D16698#457858, @nikola.lecic_anthesphoria.net wrote:

In D16698#457847, @wulf wrote:

then comment out imt_set_input_mode() call in imt_attach() subroutine (imt.c) and insert printf("something\n"); into iichid_intr() sub (iichid.c)
If it print something on the console when you touching trackpad surface?

In D16698#457858, @nikola.lecic_anthesphoria.net wrote:

In D16698#457847, @wulf wrote:

In D16698#457847, @wulf wrote:

In D16698#457762, @nikola.lecic_anthesphoria.net wrote:

Here it is.

Attach phase looks good now

Try to replace iichid_set_power() and iichid_reset() subroutine bodies in iichid.c with return(0);

In D16698#457762, @nikola.lecic_anthesphoria.net wrote:

Here it is.

In D16698#457802, @zarychtam_plan-b.pwste.edu.pl wrote:

Updated D16698 builds and runs fine on 12-STABLE though it still lacks resume support.

I must admit I wasn't able to test https://github.com/wulf7/iichid. The module didn't work for me:

Jul 28 18:20:49 bsdondell kernel: imt0: IRQ allocation failed. Fallback to sampling.

Updated D16698 builds and runs fine on 12-STABLE though it still lacks resume support.

In D16698#457750, @wulf wrote:

In D16698#457728, @nikola.lecic_anthesphoria.net wrote:

All done, no difference, nothing happens with evemu-record. :(

What is in your dmesg log? Please post it including device attachment part

In D16698#457728, @nikola.lecic_anthesphoria.net wrote:

All done, no difference, nothing happens with evemu-record. :(

In D16698#457552, @wulf wrote:

In D16698#456379, @nikola.lecic_anthesphoria.net wrote:

Touching/pressing/doing anything with touchpad produces absolutely nothing.

Ouuuch. I forgot one important thing! ig4.ko must be fixed before this driver get used. I am sorry.

Just add following snippet to ig4iic_pci_methods array in /usr/src/sys/dev/ichiic/ig4_pci.c and rebuild kernel or ig4.ko

/* Bus interface */
DEVMETHOD(bus_setup_intr, bus_generic_setup_intr),
DEVMETHOD(bus_teardown_intr, bus_generic_teardown_intr),
DEVMETHOD(bus_alloc_resource, bus_generic_alloc_resource),
DEVMETHOD(bus_release_resource, bus_generic_release_resource),
DEVMETHOD(bus_activate_resource, bus_generic_activate_resource),
DEVMETHOD(bus_deactivate_resource, bus_generic_deactivate_resource),
DEVMETHOD(bus_adjust_resource, bus_generic_adjust_resource),
DEVMETHOD(bus_set_resource, bus_generic_rl_set_resource),
DEVMETHOD(bus_get_resource, bus_generic_rl_get_resource),

In D16698#456379, @nikola.lecic_anthesphoria.net wrote:

Touching/pressing/doing anything with touchpad produces absolutely nothing.

In D16698#456208, @wulf wrote:

In D16698#456096, @nikola.lecic_anthesphoria.net wrote:

Sorry, no difference.

I enabled debugging output in imt.c so please:

1. Update sources
2. make && sudo kldload ./iichid.ko
3. sudo sysctl hw.imt.debug=6
4. sudo evemu-record /dev/input/event<touchpad unit number>
5. Do a touch for half an second
6. Post dmesg output starting form first imt0: line

In D16698#456096, @nikola.lecic_anthesphoria.net wrote:

Sorry, no difference.

I enabled debugging output in imt.c so please:

In D16698#456090, @wulf wrote:

In D16698#455908, @nikola.lecic_anthesphoria.net wrote:

The only problem -- the device is still dead;

I fixed one bug, so try one more time

In D16698#455908, @nikola.lecic_anthesphoria.net wrote:

The only problem -- the device is still dead;

I fixed one bug, so try one more time

it generates nothing with libinput debug-events, and no events in xev.

libinput debug-events is not the right tool to debug evdev. evemu-record from devel/evemu port is better

In D16698#455907, @wulf wrote:

In D16698#455794, @nikola.lecic_anthesphoria.net wrote:

Unlike with previous driver, I don't see /dev/input/event3 (HID over IIC) anymore.

That is expected as it ignored any touchpads

I added some basic touchpad support (surface touches only, no buttons) so you can try it again
Unfortunately, it is untested.

In D16698#455794, @nikola.lecic_anthesphoria.net wrote:

Unlike with previous driver, I don't see /dev/input/event3 (HID over IIC) anymore.

That is expected as it ignored any touchpads

In D16698#455669, @wulf wrote:

In D16698#455451, @nikola.lecic_anthesphoria.net wrote:

@wulf, please explain how to test this driver. Should I just compile new iichid.ko (running make in the input directory),

just unpack it at your $HOME. Than

make && sudo kldload ./iichid.ko

[...]

In D16698#455451, @nikola.lecic_anthesphoria.net wrote:

@wulf, please explain how to test this driver. Should I just compile new iichid.ko (running make in the input directory),

just unpack it at your $HOME. Than

make && sudo kldload ./iichid.ko

leaving all other modules built from the source of this thread?

drivers from this review should be at least unloaded from kernel. There is no need to revert D16698 patch. Just don't try to kldload both modules in between reboots.

Should I remove evdev support from the kernel?

No need. It links with evdev unconditionally

Can you please share your xorg configuration?

I do not have any specific xorg.conf options. Any evdev-awared autoconfiguration backend should work out of box. See https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=196678 for example.

In D16698#455438, @nikola.lecic_anthesphoria.net wrote:

Parsed:

0x05, 0x0D,        // Usage Page (Digitizer)
0x09, 0x05,        // Usage (Touch Pad)
0xA1, 0x01,        // Collection (Application)
0x85, 0x04,        //   Report ID (4)
0x09, 0x22,        //   Usage (Finger)
0xA1, 0x02,        //   Collection (Logical)

In D16698#455371, @wulf wrote:

In D16698#455200, @greg_unrelenting.technology wrote:

We have the wmt driver but right now it's *touchscreen*-only and (of course) USB-only.

I have half-completed (it is working for me!) WIP port of wmt for i2c bus https://github.com/wulf7/iichid.

In D16698#455403, @wulf wrote:

OS driver or userland applications just do not have enough information as finger coords or count to support doublefinger scroll or multifinger taps.

I wrote a simple util to dump report descriptor from I2C HID device

fetchdesc.c3 KBDownload

.
It accepts 3 input parameters: iic device path, i2c bus address and i2c HID register and prints report descriptor of given I2C device on stdout. This report descriptor can be further analyzed with any tool (e.g. web-based http://eleccelerator.com/usbdescreqparser/) to examine HID device capabilities.

OS driver or userland applications just do not have enough information as finger coords or count to support doublefinger scroll or multifinger taps.

I wrote a simple util to dump report descriptor from I2C HID device

In D16698#455238, @nikola.lecic_anthesphoria.net wrote:

I see. Sigh. Anyway, some people from this thread reported that two finger scrolling *does* work, including @johalun himself in his announcement:

If I do two finger horizontal scroll I don't get any event callbacks at all while I do for vertical. Could this be something that has to be enabled by sending some command to the device?

In D16698#455200, @greg_unrelenting.technology wrote:

We have the wmt driver but right now it's *touchscreen*-only and (of course) USB-only.

In D16698#455259, @johalun wrote:

EVDEV is still optional and the driver won't compile without the #ifdefs if it's not enabled. Just recently I think it has been enabled by default.

hm. EVDEV_SUPPORT enables evdev in "legacy" drivers like psm, ums, ukbd etc. I'm not sure why @johalun added ifdefs for that here, this is a new driver :)

In D16698#455200, @greg_unrelenting.technology wrote:

hm. EVDEV_SUPPORT enables evdev in "legacy" drivers like psm, ums, ukbd etc. I'm not sure why @johalun added ifdefs for that here, this is a new driver :)

In D16698#455093, @nikola.lecic_anthesphoria.net wrote:

In D16698#454859, @greg_unrelenting.technology wrote:

In D16698#454202, @nikola.lecic_anthesphoria.net wrote:

1. I compiled this driver with EVDEV support (https://gist.github.com/johalun/3c67a678e740b82512cec52bfe926092). How can I make use of it? I see no difference with and without this patch.

If there's a new device in /dev/input, it is working. You can run libinput debug-events to see the input events. To consume evdev devices from xorg, use xf86-input-libinput. There were patches for autodetection (one adding evdev autodetection to the devd backend, another switching to the udev backend with libudev-devd). The devd one might have been merged?? (I don't follow Xorg, I use Wayland exclusively)

Thanks; I thought that kldload evdev was enough; but kernel with EVDEV_SUPPORT was needed.

In D16698#454859, @greg_unrelenting.technology wrote:

In D16698#454202, @nikola.lecic_anthesphoria.net wrote:

1. I compiled this driver with EVDEV support (https://gist.github.com/johalun/3c67a678e740b82512cec52bfe926092). How can I make use of it? I see no difference with and without this patch.

If there's a new device in /dev/input, it is working. You can run libinput debug-events to see the input events. To consume evdev devices from xorg, use xf86-input-libinput. There were patches for autodetection (one adding evdev autodetection to the devd backend, another switching to the udev backend with libudev-devd). The devd one might have been merged?? (I don't follow Xorg, I use Wayland exclusively)

In D16698#454202, @nikola.lecic_anthesphoria.net wrote:

1. I compiled this driver with EVDEV support (https://gist.github.com/johalun/3c67a678e740b82512cec52bfe926092). How can I make use of it? I see no difference with and without this patch.

... please note that I edited my last post; touchpad is working again after test #3.

In D16698#454685, @marc.priggemeyer_gmail.com wrote:

In D16698#454202, @nikola.lecic_anthesphoria.net wrote:

Many thanks for your efforts! My laptop: Asus Zenbook 14 UX410UFR with 12.0-RELEASE. After kldload ig4 iic acpi_iichid the device works after being probed with i2c -v -s -f /dev/iic1 (thanks fbsd_opal.com). My /var/log/messages:

Could you post the full output of the i2c -v -s -f /dev/iic1 command? I just checked the implementation and i2c either uses START/STOP or reads a byte to perform a scan per address. On my laptop (using ig4), I get the following output and I think it looks similar on yours.

dev: /dev/iic1, addr: 0x0, r/w: r, offset: 0x00, width: 8, count: 1
Hardware may not support START/STOP scanning; trying less-reliable read method.
Scanning I2C devices on /dev/iic1: 2c

In D16698#454202, @nikola.lecic_anthesphoria.net wrote:

Many thanks for your efforts! My laptop: Asus Zenbook 14 UX410UFR with 12.0-RELEASE. After kldload ig4 iic acpi_iichid the device works after being probed with i2c -v -s -f /dev/iic1 (thanks fbsd_opal.com). My /var/log/messages:

Many thanks for your efforts! My laptop: Asus Zenbook 14 UX410UFR with 12.0-RELEASE. After kldload ig4 iic acpi_iichid the device works after being probed with i2c -v -s -f /dev/iic1 (thanks fbsd_opal.com). My /var/log/messages:

In D16698#452632, @markj wrote:

Oh, nice. Your iichid_identify() method is basically identical to what I wrote. You're right, it does not strictly require a separate module, it just seemed cleaner to have a generic acpi_iichid bus.

I don't object to acpi_iichid module existence. It just adds an extra requirements for module load order which I was not able to solve quickly.

I think it would be best to try and base the ims driver on top of your code. Are you interested in trying to integrate them?

Yes, I am going to submit this code to the project when it will be ready, so it is better to have it insync with ims

In D16698#452631, @wulf wrote:

I wrote a driver for I2C MT touchscreens https://github.com/wulf7/iichid which is heavily based on the code in this review.
It does not require dedicated ACPI module at all and has some I2C/HID layers separation which is missed in current review.
So I think it may have sense to join efforts and codebases

I wrote a driver for I2C MT touchscreens https://github.com/wulf7/iichid which is heavily based on the code in this review.
It does not require dedicated ACPI module at all and has some I2C/HID layers separation which is missed in current review.
So I think it may have sense to join efforts and codebases

I reuploaded the full patch with a sysctl (power_state) added.
Setting

In D16698#452198, @marc.priggemeyer_gmail.com wrote:

I just looked into Microsoft's HID over I2C specification document again. Section 8.2 deals with "Host Initiated Power Optimizations" (HIPO). There, sleep and on are explicitly stated as modes that the host should take care of:
Quote: [1]

The HOST is responsible for optimizing the power of the overall system and the DEVICE. This method of power optimization is to be used when the HOST wishes to provide power optimization notifications to devices.
The following power states are defined for HIPO and are not to be confused with vendor specific DIPO states.

• ON
• SLEEP

Section 7.2.8 specifies the SET_POWER command, so the DEVMETHODs device_suspend and device_resume should implement sleep and wakeup transitions for the human interface device. In addition, the device is not required to respond to the SET_POWER command, so it could be implemented fairly easy. Probably something like this (untested):

static int
iichid_write_register(device_t dev, uint8_t* cmd, int cmdlen)

static int
iichid_set_power(device_t dev, struct i2c_hid_desc* hid_desc, bool sleep)

In D16698#452204, @marc.priggemeyer_gmail.com wrote:

Hmm, I think I did not intend to create a new diff. Should I reupload, or can it be merged?

Hmm, I think I did not intend to create a new diff. Should I reupload, or can it be merged?

In D16698#452186, @markj wrote:

Do you have a license header for iichid.c?

In D16698#452171, @marc.priggemeyer_gmail.com wrote:

#1

In D16698#452086, @markj wrote:

The acpi_iichid driver needs to be rewritten. It should be a child of the iic bus, not the acpi bus. I've started working on this.

I will submit to the more experienced developers on this point, for completeness I would still like to include my findings here:

• The I2C Bus is not enumerable, which means that the driver won't be attached automatically if it is a child of iicbus.

#1

In D16698#452086, @markj wrote:

The acpi_iichid driver needs to be rewritten. It should be a child of the iic bus, not the acpi bus. I've started working on this.