lynxpoint: Fix an issue clearing port change status bits

The coreboot and ACPI code that clears USB3 PORTSC change status
bits was not properly preserving the state of the PED (port enabled
or disabled) status bit, and it could write 0 back to this field
which would disable the port.

Additionally add back the code that resets disconnected USB3 ports
on the way into suspend (as stated in the BWG) but take care to
clear the PME status bit so we don't immediately wake.

suspend/resume with USB3 devices

1) suspend with no devices, plug in while suspended, then resume
and verify that the devices are detected
2) suspend with USB3 devices inserted, then suspend and resume
and verify that the devices are detected
3) suspend with USB3 devices inserted, then remove the devices
while suspended, resume and ensure they can be detected again
when inserted after resume

Change-Id: Ic7e8d375dfe645cf0dc1f041c3a3d09d0ead1a51
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/65733
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Commit-Queue: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/4473
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

src/southbridge/intel/lynxpoint/acpi/usb.asl

@@ -106,23 +106,36 @@ Device (XHCI)
 		Field (XREG, DWordAcc, Lock, Preserve)
 		{
 			Offset (0x510), // PORTSCNUSB3[0]
-			, 17,
+			PSC0, 32,
-			CLR1, 7,	// Status Change bits 23:17
 			Offset (0x520), // PORTSCNUSB3[1]
-			, 17,
+			PSC1, 32,
-			CLR2, 7,	// Status Change Bits 23:17
 			Offset (0x530), // PORTSCNUSB3[2]
-			, 17,
+			PSC2, 32,
-			CLR3, 7,	// Status Change Bits 23:17
 			Offset (0x540), // PORTSCNUSB3[3]
-			, 17,
+			PSC3, 32,
-			CLR4, 7,	// Status Change Bits 23:17
 		}
 
-		Store (0x7f, CLR1)
+		// Port Enabled/Disabled (Bit 1)
-		Store (0x7f, CLR2)
+		Name (PEDB, ShiftLeft (1, 1))
-		Store (0x7f, CLR3)
+
-		Store (0x7f, CLR4)
+		// Change Status (Bits 23:17)
+		Name (CHST, ShiftLeft (0x7f, 17))
+
+		// Port 0
+		And (PSC0, Not (PEDB), Local0)
+		Or (Local0, CHST, PSC0)
+
+		// Port 1
+		And (PSC1, Not (PEDB), Local0)
+		Or (Local0, CHST, PSC1)
+
+		// Port 2
+		And (PSC2, Not (PEDB), Local0)
+		Or (Local0, CHST, PSC2)
+
+		// Port 3
+		And (PSC3, Not (PEDB), Local0)
+		Or (Local0, CHST, PSC3)
 	}
 
 	Method (LPS0, 0, Serialized)

src/southbridge/intel/lynxpoint/pch.h

@@ -366,6 +366,7 @@ int early_pch_init(const void *gpio_map,
 #define  PWR_CTL_SET_D0		0x0
 #define  PWR_CTL_SET_D3		0x3
 #define  PWR_CTL_ENABLE_PME	(1 << 8)
+#define  PWR_CTL_STATUS_PME	(1 << 15)
 
 /* EHCI Memory Registers */
 #define EHCI_USB_CMD		0x20
@@ -397,6 +398,7 @@ int early_pch_init(const void *gpio_map,
 #define  XHCI_USB3_PORTSC_WOE	(1 << 27)	/* Wake on Overcurrent */
 #define  XHCI_USB3_PORTSC_WRC	(1 << 19)	/* Warm Reset Complete */
 #define  XHCI_USB3_PORTSC_LWS  	(1 << 16)	/* Link Write Strobe */
+#define  XHCI_USB3_PORTSC_PED 	(1 << 1)	/* Port Enabled/Disabled */
 #define  XHCI_USB3_PORTSC_WPR	(1 << 31)	/* Warm Port Reset */
 #define  XHCI_USB3_PORTSC_PLS	(0xf << 5)	/* Port Link State */
 #define   XHCI_PLSR_DISABLED	(4 << 5)	/* Port is disabled */

src/southbridge/intel/lynxpoint/usb_xhci.c

@@ -61,7 +61,12 @@ static int usb_xhci_port_count_usb3(device_t dev)
 static void usb_xhci_reset_status_usb3(u32 mem_base, int port)
 {
 	u32 portsc = mem_base + XHCI_USB3_PORTSC(port);
-	write32(portsc, read32(portsc) | XHCI_USB3_PORTSC_CHST);
+	u32 status = read32(portsc);
+	/* Do not set Port Enabled/Disabled field */
+	status &= ~XHCI_USB3_PORTSC_PED;
+	/* Clear all change status bits */
+	status |= XHCI_USB3_PORTSC_CHST;
+	write32(portsc, status);
 }
 
 static void usb_xhci_reset_port_usb3(u32 mem_base, int port)
@@ -178,6 +183,9 @@ void usb_xhci_sleep_prepare(device_t dev, u8 slp_typ)
 		reg32 &= ~((1 << 14) | (1 << 2));
 		write32(mem_base + 0x816c, reg32);
 
+		/* Reset disconnected USB3 ports */
+		usb_xhci_reset_usb3(dev, 0);
+
 		/* Set MMIO 0x80e0[15] */
 		reg32 = read32(mem_base + 0x80e0);
 		reg32 |= (1 << 15);
@@ -186,6 +194,7 @@ void usb_xhci_sleep_prepare(device_t dev, u8 slp_typ)
 
 	/* Set D3Hot state and enable PME */
 	pci_or_config16(dev, XHCI_PWR_CTL_STS, PWR_CTL_SET_D3);
+	pci_or_config16(dev, XHCI_PWR_CTL_STS, PWR_CTL_STATUS_PME);
 	pci_or_config16(dev, XHCI_PWR_CTL_STS, PWR_CTL_ENABLE_PME);
 }