Re: ACPI SPI slave device

Hi Leif,

I went through my collection of MacBook acpidumps and noticed that the
MacBookPro12,1 also uses SPI, the DSDT entries are identical (save for
some changes in the ISOL method and an additional UIST method). That's
the 13" 2015 MacBookPro model.

John Horan and Henrik Rydberg added support for that model's keyboard
and trackpad with:
d58069265c9d ("Input: bcm5974 - add support for the 2015 Macbook Pro")
a4a2c54560f2 ("HID: apple: Add support for the 2015 Macbook Pro")
efbd34702fb1 ("Input: bcm5974 - prepare for a new trackpad generation")

I'm wondering, if the keyboard and trackpad are working on the MBP12,1,
why aren't they working on the MB8,1? Adding John and Henrik to cc: in
the hope of clarifying this.


On Tue, Mar 08, 2016 at 03:40:14PM +0100, Leif Liddy wrote:

quoted

We could extend drivers/acpi/property.c:acpi_init_properties() to
check if dmi_match(DMI_BOARD_VENDOR, "Apple Inc."), and instead of
calling _DSD, call _DSM with Apple's UUID and populate adev->data
with that. Or add the properties to the existing data, if any.

Lukas, this a bit beyond my skill level at the moment. I'd like to
start with something with a bit easier, and then work my way up.

Here's how I gather things are supposed to work.

The references inside the _DSM method for SPIT device: {spiSclkPeriod,
spiWordSize, spiCSDelay....etc} are meant to be parsed out and used as
parameters to configure the SPI controller/protocol driver (or not
used at all).

Yes. Call the _DSM method and you'll get back a "package". Basically
that's a fancy ACPI term for a struct. You can then retrieve the values
out of that package.

My goal at the moment is just to be able to perform basic connectivity
testing with the slave device.
The first issue I ran into was that the IRQ assigned to the DMA
controller (dw_dmac) was wrong.

/proc/interrupts
20:    dw_dmac                            --by default, it's set to 20
21:     pxa2xx-spi.0

/proc/interrupts
21:     dw_dmac, pxa2xx-spi.0    --should be set to 21 and share IRQ
with spi controller

Hm, according to DSDT the interrupt for APP000D should be 0x1E, i.e. 30.

I notice that the interrupt is specified in the device's ResourceTemplate
(_CRS.UBUF) but not in the package returned by the _DSM. If we need that
value then we cannot solve this by just parsing the values returned by the
_DSM. The only option we'd have is to retrieve that UBUF ResourceTemplate.

IRQ 21 is what is shown in the DSDT table for both the DMA and SPI
devices. I think because the DMA controller is called by its PCI ID
(dma/dw/pci.c)that's it's not checking ACPI for the IRQ value.

modprobe spi_pxa2xx_pci     --everything seems to come up fine

....
xxx pxa2xx.c setup() tx_thres: 160 tx_hi_thres: 224 rx_thres: 64
xxx pxa2xx.c setup() chip->enable_dma is 1
xxx pxa2xx.c setup() bits_per_word: 8 dma_burst_size: 1 dma_threshold: 1088
spi spi-APP000D:00: setup mode 0, 8 bits/w, 8000000 Hz max --> 0
pxa2xx-spi pxa2xx-spi.0: registered child spi-APP000D:00
....

I've modified spidev.c to bind to the APP000D slave device. However,
when I run spidev_test nothing gets received.

./spidev_test -D /dev/spidev0.0

spi mode: 0x0
bits per word: 8
max speed: 500000 Hz (500 KHz)
RX | 00 00 00 00 00 00 00 00 00 00.......

**dmesg (prink statements) shows it running through the whole dma
transfer transfer process

I'm wondering what functions SIEN, SIST, and ISOL methods are meant to
perform on the SPIT device (in the DSDT table) --and how to use them.

If you grep /System/Library/Extensions on OS X for these strings you'll
find the SPI drivers. Disassemble those and you'll find these methods are
called in the following functions:

ISOL gets called in AppleIntelLpssGspi.kext from
       AppleIntelLpssGspi::gpioConfig()
       AppleIntelLpssGspi::initGspiGpio()
SIEN gets called in AppleIntelLpssSpiController.kext from
       AppleIntelLpssSpiController::_setSPIBusDeviceEnable()
SIEN, SIST und UIST in the same kext from:
       AppleIntelLpssSpiController::getSpiDevices()

Apple often uses nonstandard ACPI methods like this for power management,
i.e. to power a chip up and down and query its status. SIEN takes one
argument which can be 1 or 0 and modifies GPIO pin 13. You'd need the
schematics of the mainboard to know what this pin is connected to but
this might be a power switch which powers the SPI controller up and down.
So the "EN" in "SIEN" might stand for "enable", which matches with the
function it's called from (_setSPIBusDeviceEnable). Likewise SIST returns
the status of GPIO pin 13 so the "ST" might stand for "status".

I don't know what ISOL does. "Isolation" maybe? This also modifies a few
GPIO registers. And UIST ist only present in the MBP12,1 DSDT, it returns
the status of GPIO pin 26.

HTH,

Lukas

Here's what I got so far:

.....................................................
static int spi_hid_probe(struct spi_device *spi)
{
        struct acpi_object_list input;
        union acpi_object param[1];
        acpi_status status;
        param[0].type = ACPI_TYPE_INTEGER;
        param[0].integer.value = 0x01;
        input.count = 1;
        input.pointer = param;

        status = acpi_evaluate_object(ACPI_HANDLE(&spi->dev), "SIEN",
&input, NULL);
        if (ACPI_FAILURE(status))
                printk("xxx mb81_spi_probe --ACPI_FAILURE\n");

        return 0;
}


static const struct acpi_device_id spi_hid_acpi_match[] = {
        { "APP000D", 0 },
        { },
};
...
...................................................

If I load & unload this test module --and then run spidev

./spidev_test -D /dev/spidev0.0  -v
spi mode: 0x0
bits per word: 8
max speed: 500000 Hz (500 KHz)
TX | FF FF FF FF FF FF 40 00 00 00 00 95 FF FF FF FF FF FF FF FF FF FF
FF FF FF FF FF FF FF FF F0 0D  | ......@....???..................???.
RX | 20 D0 00 00 00 00 04 00 A0 80 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00  | .???......??????....................

It changed something....
It looks like SIEN is modifying the GPIO registers, but its function
isn't exactly clear.


Lukas, can you help me sort out what the purpose of these methods are
and how to use them?

-----------------------------------------------------------------------------------------------

Method (SIEN, 1, Serialized)
                    {
                        If ((Arg0 <= 0x01))
                        {
                            If ((Arg0 == 0x01))
                            {
                                GP13 = 0x01
                                GD13 = 0x00
                            }
                            Else
                            {
                                GD13 = 0x01
                            }
                        }
                    }

                    Method (SIST, 0, Serialized)
                    {
                        Local0 = GD13 /* \GD13 */
                        If ((Local0 == 0x01))
                        {
                            Return (GL13) /* \GL13 */
                        }
                        Else
                        {
                            Return (GP13) /* \GP13 */
                        }
                    }
                }

                Method (ISOL, 1, Serialized)
                {
                    If ((Arg0 <= 0x01))
                    {
                        If ((Arg0 == 0x01))
                        {
                            GP87 = 0x01
                            GP88 = 0x00
                            GP89 = 0x00
                            GP90 = 0x00
                            GD87 = 0x00
                            GD88 = 0x00
                            GD89 = 0x01
                            GD90 = 0x00
                            GU87 = 0x01
                            GU88 = 0x01
                            GU89 = 0x01
                            GU90 = 0x01
                            Local0 = GP87 /* \GP87 */
                        }
                        Else
                        {
                            GU87 = 0x00
                            GU88 = 0x00
                            GU89 = 0x00
                            GU90 = 0x00
                            GP87 = 0x00
                            GP88 = 0x00
                            GP89 = 0x00
                            GP90 = 0x00
                            GD87 = 0x00
                            GD88 = 0x00
                            GD89 = 0x00
                            GD90 = 0x00
                            Local0 = GU87 /* \GU87 */
                        }

                        Return (0x00)
                    }

                    Return (0xFFFFFFFF)
                }
            }

-----------------------------------------------------------------------------------------------

Decoded DSDT table:
https://bugzilla.kernel.org/attachment.cgi?id=202141

On Thu, Mar 3, 2016 at 8:12 PM, Matthew Garrett [off-list ref] wrote:

quoted

On Thu, Mar 03, 2016 at 07:55:53PM +0100, Lukas Wunner wrote:

quoted

We could extend drivers/acpi/property.c:acpi_init_properties() to
check if dmi_match(DMI_BOARD_VENDOR, "Apple Inc."), and instead of
calling _DSD, call _DSM with Apple's UUID and populate adev->data
with that. Or add the properties to the existing data, if any.

Just do it unconditionally, it's cheap.

quoted

E.g. in the case of this SPI slave we need to fill in five values
of struct spi_device and we would add a quirk for APP000D which
retrieves each value via acpi_dev_get_property() instead of
acpi_dev_get_resources().

Mm. It'd be nice to avoid having to keep a list of Apple devices - some
sort of mapping function might be easier, returning the values from _CRS
if they're present or from _DSM/_DSD otherwise?

--
Matthew Garrett | mjg59-1xO5oi07KQx4cg9Nei1l7Q@public.gmane.org

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