[PATCH 1/3][SRU][Unstable] PCI/ASPM: Introduce a new helper to report ASPM capability

[AceLan Kao]

From: Kai-Heng Feng <kai.heng.feng at canonical.com>

BugLink: https://bugs.launchpad.net/bugs/1946433

Introduce a new helper, pcie_aspm_capable(), to report ASPM capability.

The user will be introduced by next patch.

Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
Acked-by: Bjorn Helgaas <bhelgaas at google.com>
(cherry picked from
https://patchwork.ozlabs.org/project/linux-pci/patch/20211007161552.272771-2-kai.heng.feng@canonical.com/)
Signed-off-by: Chia-Lin Kao (AceLan) <acelan.kao at canonical.com>
---
 drivers/pci/pcie/aspm.c | 11 +++++++++++
 include/linux/pci.h     |  2 ++
 2 files changed, 13 insertions(+)

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 04bf45a31980..9523cd6468ee 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -1202,6 +1202,17 @@ bool pcie_aspm_enabled(struct pci_dev *pdev)
 }
 EXPORT_SYMBOL_GPL(pcie_aspm_enabled);
 
+bool pcie_aspm_capable(struct pci_dev *pdev)
+{
+	struct pcie_link_state *link = pcie_aspm_get_link(pdev);
+
+	if (!link)
+		return false;
+
+	return link->aspm_capable;
+}
+EXPORT_SYMBOL_GPL(pcie_aspm_capable);
+
 static ssize_t aspm_attr_show_common(struct device *dev,
 				     struct device_attribute *attr,
 				     char *buf, u8 state)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index ffa4af9c010b..d086cdd3e4ab 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1641,6 +1641,7 @@ int pci_disable_link_state_locked(struct pci_dev *pdev, int state);
 void pcie_no_aspm(void);
 bool pcie_aspm_support_enabled(void);
 bool pcie_aspm_enabled(struct pci_dev *pdev);
+bool pcie_aspm_capable(struct pci_dev *pdev);
 #else
 static inline int pci_disable_link_state(struct pci_dev *pdev, int state)
 { return 0; }
@@ -1649,6 +1650,7 @@ static inline int pci_disable_link_state_locked(struct pci_dev *pdev, int state)
 static inline void pcie_no_aspm(void) { }
 static inline bool pcie_aspm_support_enabled(void) { return false; }
 static inline bool pcie_aspm_enabled(struct pci_dev *pdev) { return false; }
+static inline bool pcie_aspm_capable(struct pci_dev *pdev) { return false; }
 #endif
 
 #ifdef CONFIG_PCIEAER
-- 
2.25.1