[Linux-kernel-mentees] [RFC PATCH v5 02/23] PCI: Add l1ss_cap and l1ss_cap_ptr to struct pci_dev

[Saheed O. Bolarinwa]

 - Add l1ss_cap and l1ss_cap_ptr to struct pci_dev
 - Compute the value of pci_dev.l1ss_cap and pci_dev.l1ss_cap_ptr

Signed-off-by: Saheed O. Bolarinwa <refactormyself at gmail.com>
---
 drivers/pci/probe.c | 6 ++++++
 include/linux/pci.h | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 6cae7230f3b5..787ab6e831c7 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2101,6 +2101,12 @@ static void pci_configure_ltr(struct pci_dev *dev)
 	if (!pci_is_pcie(dev))
 		return;
 
+	/* Read L1 PM substate capabilities */
+	dev->l1ss_cap_ptr = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_L1SS);
+	if (dev->l1ss_cap_ptr)
+		pci_read_config_dword(dev, dev->l1ss_cap_ptr + PCI_L1SS_CAP,
+								&dev->l1ss_cap);
+
 	pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);
 	if (!(cap & PCI_EXP_DEVCAP2_LTR))
 		return;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 3d30d3650ac9..fa114c5d01e7 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -381,6 +381,8 @@ struct pci_dev {
 	struct pcie_link_state	*link_state;	/* ASPM link state */
 	unsigned int	ltr_path:1;	/* Latency Tolerance Reporting
 					   supported from root to here */
+	int		l1ss_cap_ptr;	/* L1SS cap ptr, 0 if not supported */
+	u32		l1ss_cap;	/* L1 PM substate Capabilities */
 #endif
 	unsigned int	eetlp_prefix_path:1;	/* End-to-End TLP Prefix */
 
-- 
2.18.4