Hi Mika

-----Original Message-----
From: Mika Westerberg [mailto:mika.westerberg at linux.intel.com]
Sent: 13 June 2017 09:49
To: Lorenzo Pieralisi
Cc: Gabriele Paoloni; rafael at kernel.org; Rafael J. Wysocki;
catalin.marinas at arm.com; will.deacon at arm.com; robh+dt at kernel.org;
frowand.list at gmail.com; bhelgaas at google.com; arnd at arndb.de; linux-arm-
kernel at lists.infradead.org; mark.rutland at arm.com;
brian.starkey at arm.com; olof at lixom.net; benh at kernel.crashing.org; linux-
kernel at vger.kernel.org; linux-acpi at vger.kernel.org; Linuxarm; linux-
pci at vger.kernel.org; minyard at acm.org; John Garry; xuwei (O)
Subject: Re: [PATCH v9 5/7] ACPI: Translate the I/O range of non-MMIO
devices before scanning

On Mon, Jun 12, 2017 at 04:57:00PM +0100, Lorenzo Pieralisi wrote:

quoted

I had a more in-depth look at this series and from my understanding
the problem are the following to manage the LPC bindings in ACPI.

(1) Child devices of an LPC controller require special handling when
    filling their resources (ie they need to be translated - in DT
    that's guaranteed by the "isa" binding, in ACPI it has to be
    done by new code)
(2) In DT systems, LPC child devices are created by the LPC bus
    controller driver through an of_platform_populate() call with
    the LPC controller node as the fwnode root. For ACPI to work
    the same way there must be a way to prevent LPC children to
    be enumerated in acpi_default_enumeration() something like
    I2C does (and then the LPC driver would enumerate its children as
    DT does)

I am not sure how (1) and (2) can be managed with current ACPI

bindings

quoted

and kernel code - I suspect it may be done by mirroring what's done
for I2C but I am not sure, that's why I CC'ed Mika (ie the LPC

adapter

quoted

is matched as a platform device and it takes care of enumerating its
children - problem though is preventing enumeration from core ACPI

code).

Is there an example ASL showing how these LPC devices are
currently presented in ACPI?

Please find below the asl sketch for our LPC and IPMI

//
// LPC
//

Scope(_SB) {
  Device (LPC0) {
    Name (_HID, "HISI0191")  // HiSi LPC
    Name (_CRS, ResourceTemplate () {
      Memory32Fixed (ReadWrite, 0xa01b0000, 0x1000)
    })
  }

  Device (LPC0.IPMI) {
    Name (_HID, "IPI0001")
    Method (_IFT) {
      Return (0x03)
    }
    Name (LORS, ResourceTemplate() {
      QWordIO (
        ResourceConsumer,
	MinNotFixed,     // _MIF
	MaxNotFixed,     // _MAF
	PosDecode,
	EntireRange,
	0x0,             // _GRA
	0xe4,            // _MIN
	0x3fff,          // _MAX
	0x0,             // _TRA
	0x04,            // _LEN
	, ,
	BTIO
      )
    })
    CreateQWordField (LORS, BTIO._MIN, CMIN)
    CreateQWordField (LORS, BTIO._MAX, CMAX)
    CreateQWordField (LORS, BTIO._LEN, CLEN)

    Method (_PRS, 0) {
      Return (LORS)
    }

    Method (_CRS, 0) {
      Return (LORS)
    }
    Method (_SRS, 1) {
      CreateQWordField (Arg0, \_SB.LPC0.IPMI.BTIO._MIN, IMIN)
      Store (IMIN, CMIN)
      CreateQWordField (Arg0, \_SB.LPC0.IPMI.BTIO._MAX, IMAX)
      Store (IMAX, CMAX)
    }
  } 
[...]
}

Many thanks
Gab