PCI: Add pcie_ptm_enabled()

Add a predicate that returns if PCIe PTM (Precision Time Measurement)
is enabled.

It will only return true if it's enabled in all the ports in the path
from the device to the root.
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/pci/pcie/ptm.c

@@ -204,3 +204,12 @@ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
 	return 0;
 }
 EXPORT_SYMBOL(pci_enable_ptm);
+
+bool pcie_ptm_enabled(struct pci_dev *dev)
+{
+	if (!dev)
+		return false;
+
+	return dev->ptm_enabled;
+}
+EXPORT_SYMBOL(pcie_ptm_enabled);

include/linux/pci.h

@@ -1622,9 +1622,12 @@ bool pci_ats_disabled(void);
 
 #ifdef CONFIG_PCIE_PTM
 int pci_enable_ptm(struct pci_dev *dev, u8 *granularity);
+bool pcie_ptm_enabled(struct pci_dev *dev);
 #else
 static inline int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
 { return -EINVAL; }
+static inline bool pcie_ptm_enabled(struct pci_dev *dev)
+{ return false; }
 #endif
 
 void pci_cfg_access_lock(struct pci_dev *dev);