soc/intel/{sky,apollo}lake: Wait until GPE is clear when reading

When reading+clearing a GPE for use as an interrupt we need to
re-read the status register and keep setting the clear bit until
it actually reads back clear.  Also add a 1ms timeout in case the
status never clears.

This is needed if a device sends a longer interrupt pulse and it
is still asserted when the "ISR" goes to clear the status.

BUG=chrome-os-partner:59299
TEST=test cr50 TPM with 20us pulse to ensure it can successfully
communicate with the TPM and does not get confused due to seeing
interrupts that it should not.

Change-Id: I384f484a1728038d3a355586146deee089b22dd9
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/17212
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

1 files changed, 17 insertions, 6 deletions

diff --git a/src/soc/intel/apollolake/pmutil.c b/src/soc/intel/apollolake/pmutil.c
index 80aaf715af..c88e5ae8bf 100644
--- a/src/soc/intel/apollolake/pmutil.c
+++ b/src/soc/intel/apollolake/pmutil.c
@@ -29,6 +29,7 @@
 #include <soc/pm.h>
 #include <device/device.h>
 #include <device/pci.h>
+#include <timer.h>
 #include <vboot/vboot_common.h>
 #include "chip.h"
 
@@ -306,6 +307,8 @@ int acpi_get_gpe(int gpe)
 {
 	int bank;
 	uint32_t mask, sts;
+	struct stopwatch sw;
+	int rc = 0;
 
 	if (gpe < 0 || gpe > GPE0_DW3_31)
 		return -1;
@@ -313,12 +316,20 @@ int acpi_get_gpe(int gpe)
 	bank = gpe / 32;
 	mask = 1 << (gpe % 32);
 
-	sts = inl(ACPI_PMIO_BASE + GPE0_STS(bank));
-	if (sts & mask) {
-		outl(mask, ACPI_PMIO_BASE + GPE0_STS(bank));
-		return 1;
-	}
-	return 0;
+	/* Wait up to 1ms for GPE status to clear */
+	stopwatch_init_msecs_expire(&sw, 1);
+	do {
+		if (stopwatch_expired(&sw))
+			return rc;
+
+		sts = inl(ACPI_PMIO_BASE + GPE0_STS(bank));
+		if (sts & mask) {
+			outl(mask, ACPI_PMIO_BASE + GPE0_STS(bank));
+			rc = 1;
+		}
+	} while (sts & mask);
+
+	return rc;
 }
 
 void clear_pmc_status(void)