[PATCH v2 1/2] PCI: PCIe: ASPM: Introduce pcie_aspm_enabled_mask()

[rjw@rjwysocki.net (Rafael J. Wysocki)]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Add a function returning the mask of currently enabled ASPM link
states for a given device.

It will be used by the NVMe driver to decide how to handle the
device during system suspend.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
---

-> v2:
  * Move the PCI/PCIe ASPM changes to a separate patch.
  * Add the _mask suffix to the new function name.
  * Add EXPORT_SYMBOL_GPL() to the new function.
  * Avoid adding an unnecessary blank line.

---
 drivers/pci/pcie/aspm.c |   20 ++++++++++++++++++++
 include/linux/pci.h     |    3 +++
 2 files changed, 23 insertions(+)

Index: linux-pm/drivers/pci/pcie/aspm.c
===================================================================
--- linux-pm.orig/drivers/pci/pcie/aspm.c
+++ linux-pm/drivers/pci/pcie/aspm.c
@@ -1170,6 +1170,26 @@ static int pcie_aspm_get_policy(char *bu
 module_param_call(policy, pcie_aspm_set_policy, pcie_aspm_get_policy,
 	NULL, 0644);
 
+/*
+ * pcie_aspm_enabled_mask - Return the mask of enabled ASPM link states.
+ * @pci_device: Target device.
+ */
+u32 pcie_aspm_enabled_mask(struct pci_dev *pci_device)
+{
+	struct pci_dev *bridge = pci_upstream_bridge(pci_device);
+	u32 ret;
+
+	if (!bridge)
+		return 0;
+
+	mutex_lock(&aspm_lock);
+	ret = bridge->link_state ? bridge->link_state->aspm_enabled : 0;
+	mutex_unlock(&aspm_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pcie_aspm_enabled_mask);
+
 #ifdef CONFIG_PCIEASPM_DEBUG
 static ssize_t link_state_show(struct device *dev,
 		struct device_attribute *attr,
Index: linux-pm/include/linux/pci.h
===================================================================
--- linux-pm.orig/include/linux/pci.h
+++ linux-pm/include/linux/pci.h
@@ -1567,8 +1567,11 @@ extern bool pcie_ports_native;
 
 #ifdef CONFIG_PCIEASPM
 bool pcie_aspm_support_enabled(void);
+u32 pcie_aspm_enabled_mask(struct pci_dev *pci_device);
 #else
 static inline bool pcie_aspm_support_enabled(void) { return false; }
+static inline u32 pcie_aspm_enabled_mask(struct pci_dev *pci_device)
+{ return 0; }
 #endif
 
 #ifdef CONFIG_PCIEAER