Hi Andy,

I am resurrecting this thread now that ACPICA seemed to finally have
fixed the bug that prevent the driver to work.
The patch I submitted was reverted shortly after, which lead me to
ignore this review until ACPICA was fixed. It took a lot of effort
from Hans to have a fix accepted, so now we can hope to upstream this
driver.

On Fri, Jun 30, 2017 at 6:37 PM Andy Shevchenko
[off-list ref] wrote:

On Fri, Jun 30, 2017 at 6:57 PM, Benjamin Tissoires
[off-list ref] wrote:

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On Jun 29 2017 or thereabouts, Andy Shevchenko wrote:

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On Thu, Jun 29, 2017 at 3:10 PM, Benjamin Tissoires
[off-list ref] wrote:

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What devices (laptops, tablets) have it?
Surface 3. What else?

So far, Surface 3 only. It's a Microsoft PNPId, so I guess they control
which device has it. Maybe the model after the Surface 3 (reduced
platform) will have such chip, but for now, it's unknown.

Please, extend introduction in commit message to state above.

OK. On this note, I have been mentioned that the Surface Pro 2017 uses
a similar mechanism as in it's also using an operation region handler,
but this time over UART, not I2C :)

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I couldn't manage to get the IRQ correctly triggered, so I am using a
good old polling thread to check for changes.

It might be

It seems I didn't finished the sentence here.

I though it might be actually ACPI event, GPE or direct IRQ (when GPIO
chip should not disable it, though if it's the case it likely a BIOS
bug for this hardware).

If you don't mind, I'd rather have the polling version that seems to
be working first. I haven't touched the logs I had from Windows since
last year, so I am a little bit rusty on debugging this.
FWIW, /proc/interrupts doesn't change a bit when I unplug/replug the
power cable.

My guess is that the Windows driver initializes the chip in a
different way and this enables the cable detection.

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+       help
+         Select this option to enable support for ACPI operation
+         region of the Surface 3 battery platform driver.

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+/*
+ * Supports for the power IC on the Surface 3 tablet.

Shouldn't it go to drivers/acpi/pmic folder ?

Already answered later in the thread, so yes, I'll move it there.

Actually Hans did a good point, so, feel free to use drivers/platform/x86.

Roger that!

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And did you check if it have actual chip IP vendor name and model?
Most likely it's a TI (based?) solution.

As mentioned, I have strictly no idea. I can not crack open the Surface
3 without breaking the warranty (I already had to return it once because
the disk crashed).

We have one indeed cracked (screen is broken for good :-) ), so, I
would check what I can find there.

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And I do not find anything brand-related under Windows either:
- it's called "Surface Platform Power Driver"
- and the driver is provided by Microsoft

Fair enough.

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+static int mshw0011_bix(struct mshw0011_data *cdata, struct bix *bix)
+{

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+       memcpy(bix->serial, buf + 7, 3);
+       memcpy(bix->serial + 3, buf, 6);
+       bix->serial[9] = '\0';

snprintf()?

probably :)

I would do this until we have an evidence that it contains non-printable symbols
(or, in case you want to fix ahead, make the buffer 4 times bigger and use %*pE)

I can't really make the buffer 4 time bigger. The buffer is then used
by the DSDT table to report the _BIX status, so the length of 10 is
mandatory.
It doesn't seem to hurt, and worse case, we will just strip the
serial, not a big deal IMO.

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+       memcpy(bix->OEM, buf, 3);
+       bix->OEM[4] = '\0';

snprintf() ?

Ditto.

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+       snprintf(prefix, ARRAY_SIZE(prefix), "%s: ", bat0->name);

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+       prefix[127] = '\0';

Why?

Just me being paranoid in case the code doesn't follow the spec... Yeah, I'll
remove it.

snprintf() despite n in the name takes care of terminating NUL.

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+static int mshw0011_probe(struct i2c_client *client,
+                         const struct i2c_device_id *id)
+{

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+       data->notify_version = version == MSHW0011_EV_2_5;

0x1ff as version sounds hmm suspicious.

So after a little bit of digging, it appears those values were taken
from the DSDT:
https://bugzilla.kernel.org/attachment.cgi?id=187171 line 11694.

It appears 0x3F is EV 2.1 and before, and 0x1FF is EV 2.5 and above.
The returned value is not a version of the chip, just a flag to know
which path we are taking in the DSM.

The name is probably not the best.

63 and 511 looks too suspicious to be a version. Rather block size, a
mask or alike.

I replaced the 'version' by 'mask' in v3. It doesn't hurt to do so.

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+static const struct i2c_device_id mshw0011_id[] = {
+       { }
+};
+MODULE_DEVICE_TABLE(i2c, mshw0011_id);

->probe_new(), please.

Correct

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If I2C framework is _still_ broken we need to fix that part.

I haven't check, so let's see for v3.

Cc: Wolfram for v3 and ask him directly. Last time I checked it looks
like I2C core doesn't care about ACPI when ->probe_new() is used.

Looks like things are working fine now. So I can just submit the
driver without bothering the I2C core team :)

Cheers,
Benjamin