[PATCH] PCI: Work around poweroff & suspend-to-RAM issue on Macbook Pro 11

[Bjorn Helgaas <helgaas@xxxxxxxxxx>]

Neither soft poweroff (transition to ACPI power state S5) nor
suspend-to-RAM (transition to state S3) works on the Macbook Pro 11,4 and
11,5.

The problem is related to the [mem 0x7fa00000-0x7fbfffff] space.  When we
use that space, e.g., by assigning it to the 00:1c.0 Root Port, the ACPI
Power Management 1 Control Register (PM1_CNT) at [io 0x1804] doesn't work
anymore.

Linux does a soft poweroff (transition to S5) by writing to PM1_CNT.  The
theory about why this doesn't work is:

  - The write to PM1_CNT causes an SMI
  - The BIOS SMI handler depends on something in
    [mem 0x7fa00000-0x7fbfffff]
  - When Linux assigns [mem 0x7fa00000-0x7fbfffff] to the 00:1c.0 Port, it
    covers up whatever the SMI handler uses, so the SMI handler no longer
    works correctly

Reserve the [mem 0x7fa00000-0x7fbfffff] space so we don't assign it to
anything.

This is voodoo programming, since we don't know what the real conflict is,
but we've failed to find the root cause.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=103211
Tested-by: thejoe@xxxxxxxxx
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Cc: Rafael J. Wysocki <rafael@xxxxxxxxxx>
Cc: Lukas Wunner <lukas@xxxxxxxxx>
Cc: Chen Yu <yu.c.chen@xxxxxxxxx>

diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c
index 6d52b94f4bb9..20fa7c84109d 100644
--- a/arch/x86/pci/fixup.c
+++ b/arch/x86/pci/fixup.c
@@ -571,3 +571,35 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x2fc0, pci_invalid_bar);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x6f60, pci_invalid_bar);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x6fa0, pci_invalid_bar);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x6fc0, pci_invalid_bar);
+
+/*
+ * Apple MacBook Pro: Avoid [mem 0x7fa00000-0x7fbfffff]
+ *
+ * Using the [mem 0x7fa00000-0x7fbfffff] region, e.g., by assigning it to
+ * the 00:1c.0 Root Port, causes a conflict with [io 0x1804], which is used
+ * for soft poweroff and suspend-to-RAM.
+ *
+ * As far as we know, this is related to the address space, not to the Root
+ * Port itself.  Attaching the quirk to the Root Port is a convenience, but
+ * it could probably also be a standalone DMI quirk.
+ *
+ * https://bugzilla.kernel.org/show_bug.cgi?id=103211
+ */
+static void quirk_apple_mbp_poweroff(struct pci_dev *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+
+	if ((!dmi_match(DMI_PRODUCT_NAME, "MacBookPro11,4") &&
+	     !dmi_match(DMI_PRODUCT_NAME, "MacBookPro11,5")) ||
+	    pdev->bus->number != 0 || pdev->devfn != PCI_DEVFN(0x1c, 0))
+		return;
+
+	res = request_mem_region(0x7fa00000, 0x200000,
+				 "MacBook Pro poweroff workaround");
+	if (res)
+		dev_info(dev, "claimed %s %pR\n", res->name, res);
+	else
+		dev_info(dev, "can't work around MacBook Pro poweroff issue\n");
+}
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x8c10, quirk_apple_mbp_poweroff);