[coreboot-gerrit] Change in coreboot[master]: drivers/genesyslogic/gl9755: Adjust L1 exit latency to enable ASPM

[Duncan Laurie (Code Review)]

Duncan Laurie has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/47682 )

Change subject: drivers/genesyslogic/gl9755: Adjust L1 exit latency to enable ASPM
......................................................................

drivers/genesyslogic/gl9755: Adjust L1 exit latency to enable ASPM

Configure the CFG2 register to set the latency to <64us in order
to ensure the L1 exit latency is consistent across devices and that
L1 ASPM is always enabled.

BUG=b:173207454
TEST=Verify the device and link capability and control for L1:
DevCap: Latency L1 <64us
LnkCap: Latency L1 <64us
LnkCtl: ASPM L1 Enabled

Signed-off-by: Duncan Laurie 
Change-Id: Ie2b85a6697f164fbe4f84d8cd5acb2b5911ca7a9
---
M src/drivers/genesyslogic/gl9755/gl9755.c
M src/drivers/genesyslogic/gl9755/gl9755.h
2 files changed, 18 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/82/47682/1

diff --git a/src/drivers/genesyslogic/gl9755/gl9755.c b/src/drivers/genesyslogic/gl9755/gl9755.c
index c3cdef1..ed76457 100644
--- a/src/drivers/genesyslogic/gl9755/gl9755.c
+++ b/src/drivers/genesyslogic/gl9755/gl9755.c
@@ -12,13 +12,23 @@

static void gl9755_init(struct device *dev)
 {
+	uint32_t reg;
+
    printk(BIOS_INFO, "GL9755: init\n");
    pci_dev_init(dev);

/* Set Vendor Config to be configurable */
    pci_or_config32(dev, CFG, CFG_EN);
+
    /* Set LTR value */
    pci_write_config32(dev, LTR, NO_SNOOP_SCALE|NO_SNOOP_VALUE|SNOOP_SCALE|SNOOP_VALUE);
+
+	/* Adjust L1 exit latency to enable ASPM */
+	reg = pci_read_config32(dev, CFG2);
+	reg &= ~CFG2_LAT_L1_MASK;
+	reg |= CFG2_LAT_L1_ASPM;
+	pci_write_config32(dev, CFG2, reg);
+
    /* Set Vendor Config to be non-configurable */
    pci_and_config32(dev, CFG, ~CFG_EN);
 }
diff --git a/src/drivers/genesyslogic/gl9755/gl9755.h b/src/drivers/genesyslogic/gl9755/gl9755.h
index 2d20faf..0492fab 100644
--- a/src/drivers/genesyslogic/gl9755/gl9755.h
+++ b/src/drivers/genesyslogic/gl9755/gl9755.h
@@ -1,11 +1,19 @@
 /* SPDX-License-Identifier: GPL-2.0-only */

+#ifndef DRIVERS_GENESYSLOGIC_GL9755_H
+#define DRIVERS_GENESYSLOGIC_GL9755_H
+
 /* Definitions for Genesys Logic GL9755 */

#define CFG		0x800
 #define   CFG_EN	0x1
+#define CFG2			0x48
+#define   CFG2_LAT_L1_MASK	((0x7 << 12) | (0x7 << 3))
+#define   CFG2_LAT_L1_ASPM	((0x6 << 12) | (0x6 << 3))
 #define LTR			0x5C
 #define   SNOOP_VALUE		0x25
 #define   SNOOP_SCALE		(0x3 << 10)
 #define   NO_SNOOP_VALUE	(0x25 << 16)
 #define   NO_SNOOP_SCALE	(0x3 << 26)
+
+#endif /* DRIVERS_GENESYSLOGIC_GL9755_H */