Re: Adding I2C devices to the SMBus (PIIX4) via the ACPI SSDT overlay method

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Fri, Nov 08, 2024 at 02:48:44PM +0300, Konstantin Aladyshev wrote:
> Thanks for the help!


> $ cat /sys/bus/acpi/devices/device\:25/path

These cat:s you made are mostly useless in this case. And you should look for
the real device folders in sysfs and firmware_node links there.

...

> However I was using the at24 device only as an example.
> My real target device is jc42
> (https://github.com/torvalds/linux/blob/906bd684e4b1e517dd424a354744c5b0aebef8af/drivers/hwmon/jc42.c#L600).

> Does it mean that jc42 driver doesn't support ACPI binding?

Kinda. I just sent a patch, please test and provide your Tested-by if it helps.

...

> Just in case here is my SSDT:
> ```
> DefinitionBlock ("jc42.aml", "SSDT", 5, "", "JC42", 1)
> {
>     External (_SB_.PCI0.SMBS, DeviceObj)
> 
>     Scope (\_SB_.PCI0.SMBS)
>     {
>         Device (SMB0) {
>             Name (_ADR, 0)
>         }
>         Device (SMB1) {
>             Name (_ADR, 1)
>         }
>         Device (SMB2) {
>             Name (_ADR, 2)
>         }
>     }
> 
>     Scope (\_SB.PCI0.SMBS)

While this works, we expect Scope to be under the respective host controller, i.e.

     Scope (\_SB.PCI0.SMBS.SMB0)

in your case.

>     {
>         Device (JC42) {
>             Name (_HID, "PRP0001")
>             Name (_DDN, "JC42 Temperature sensor")
>             Name (_CRS, ResourceTemplate () {
>                 I2cSerialBusV2 (
>                     0x001c,              // I2C Slave Address
>                     ControllerInitiated,
>                     400000,              // Bus speed
>                     AddressingMode7Bit,
>                     "\\_SB.PCI0.SMBS.SMB0",   // Link to ACPI I2C host
> controller
>                     0
>                 )
>             })
> 
>             Name (_DSD, Package () {
>                 ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
>                 Package () {
>                     Package () { "compatible", Package() {
> "jedec,jc-42.4-temp" } },
>                 }
>             })
>         }
>     }
> }

-- 
With Best Regards,
Andy Shevchenko