lynxpoint: Do not put SerialIO devices into D3Hot in ACPI mode

Remove the bit of code that was putting the SerialIO devices into
D3Hot state when they are switched from PCI to ACPI mode.  Instead,
add the appropriate ACPI Methods to allow the kernel to control the
power state of the device.

The problem seems to be that if the device is put in D3Hot state
before it is switched from PCI to ACPI mode then it does not properly
export its PCI configuration space and cannot be woken back up.

Adding the ACPI Methods for _PS0/_PS3 allows the kernel to transition
the device into D0 state only when it is necessary to communicate with
the device, then put it back into D3Hot state.

Change-Id: I2384ba10bf47750d1c1a35216169ddeee26881df
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/5193
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

2 files changed, 44 insertions, 10 deletions

diff --git a/src/southbridge/intel/lynxpoint/acpi/serialio.asl b/src/southbridge/intel/lynxpoint/acpi/serialio.asl
index 4c0d36bcc6..59228d6cf5 100644
--- a/src/southbridge/intel/lynxpoint/acpi/serialio.asl
+++ b/src/southbridge/intel/lynxpoint/acpi/serialio.asl
@@ -211,6 +211,28 @@ Device (I2C0)
 			Return (0xF)
 		}
 	}
+
+	// Access to PCI Config in ACPI mode
+	OperationRegion (KEYS, SystemMemory, \S1B1, 0x100)
+	Field (KEYS, DWordAcc, NoLock, Preserve)
+	{
+		Offset (0x84),
+		PSAT, 32,
+	}
+
+	// Put controller in D0 state
+	Method (_PS0, 0, Serialized)
+	{
+		And (^PSAT, 0xfffffffc, ^PSAT)
+		Store (^PSAT, Local0)
+	}
+
+	// Put controller in D3Hot state
+	Method (_PS3, 0, Serialized)
+	{
+		Or (^PSAT, 0x00000003, ^PSAT)
+		Store (^PSAT, Local0)
+	}
 }
 
 Device (I2C1)
@@ -262,6 +284,28 @@ Device (I2C1)
 			Return (0xF)
 		}
 	}
+
+	// Access to PCI Config in ACPI mode
+	OperationRegion (KEYS, SystemMemory, \S2B1, 0x100)
+	Field (KEYS, DWordAcc, NoLock, Preserve)
+	{
+		Offset (0x84),
+		PSAT, 32,
+	}
+
+	// Put controller in D0 state
+	Method (_PS0, 0, Serialized)
+	{
+		And (^PSAT, 0xfffffffc, ^PSAT)
+		Store (^PSAT, Local0)
+	}
+
+	// Put controller in D3Hot state
+	Method (_PS3, 0, Serialized)
+	{
+		Or (^PSAT, 0x00000003, ^PSAT)
+		Store (^PSAT, Local0)
+	}
 }
 
 Device (SPI0)
diff --git a/src/southbridge/intel/lynxpoint/serialio.c b/src/southbridge/intel/lynxpoint/serialio.c
index 8257cc2f6f..75edf5c9db 100644
--- a/src/southbridge/intel/lynxpoint/serialio.c
+++ b/src/southbridge/intel/lynxpoint/serialio.c
@@ -29,14 +29,6 @@
 #include "pch.h"
 #include "nvs.h"
 
-/* Set D3Hot Power State in ACPI mode */
-static void serialio_enable_d3hot(struct device *dev)
-{
-	u32 reg32 = pci_read_config32(dev, PCH_PCS);
-	reg32 |= PCH_PCS_PS_D3HOT;
-	pci_write_config32(dev, PCH_PCS, reg32);
-}
-
 /* Enable clock in PCI mode */
 static void serialio_enable_clock(struct resource *bar0)
 {
@@ -178,8 +170,6 @@ static void serialio_init(struct device *dev)
 
 	if (!config->sio_acpi_mode)
 		serialio_enable_clock(bar0);
-	else if (dev->path.pci.devfn != PCI_DEVFN(21, 0))
-		serialio_enable_d3hot(dev); /* all but SDMA */
 
 	switch (dev->path.pci.devfn) {
 	case PCI_DEVFN(21, 0): /* SDMA */