pci: Add method to read PME capability

Add a helper method to read the PME capability.
Will be used in the following commit.

Change-Id: Id1fdc98c9ce86d3ddf8056bb609afc58008cf2e9
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/84793
Reviewed-by: Shuo Liu <shuo.liu@intel.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>

src/device/pci_device.c

@@ -1345,6 +1345,24 @@ uint16_t pci_find_cap_recursive(const struct device *dev, uint16_t cap)
 	return pos;
 }
 
+/**
+ * Returns if the device support PMEs.
+ *
+ * @param dev Pointer to the device structure.
+ * @return Returns true when the device support PMEs. The PME generation can be
+ *  disabled though.
+ */
+bool pci_has_pme_pin(const struct device *dev)
+{
+	const uint16_t cap = pci_find_capability(dev, PCI_CAP_ID_PM);
+	if (!cap)
+		return false;
+
+	const uint16_t pmecap = pci_read_config16(dev, cap + PCI_PM_PMC);
+
+	return !!(pmecap & PCI_PM_CAP_PME);
+}
+
 /**
  * PCI devices that are marked as "hidden" do not get probed. However, the same
  * initialization logic is still performed as if it were. This is useful when

src/include/device/pci.h

@@ -98,6 +98,7 @@ void pci_dev_set_subsystem(struct device *dev, unsigned int vendor,
 void pci_dev_init(struct device *dev);
 unsigned int pci_match_simple_dev(struct device *dev, pci_devfn_t sdev);
 uint16_t pci_find_cap_recursive(const struct device *dev, uint16_t cap);
+bool pci_has_pme_pin(const struct device *dev);
 
 const char *pin_to_str(int pin);
 int get_pci_irq_pins(struct device *dev, struct device **parent_bdg);