[RFC v2 3/5] PCIe, Add runtime PM support to PCIe port

[Huang Ying <ying.huang@intel.com>]

From: Zheng Yan <zheng.z.yan@intel.com>

This patch adds runtime PM support to PCIe port.  This is needed by
PCIe D3cold support, where PCIe device in slot may be powered on/off
by PCIe port.

Because runtime suspend is broken for some chipset, a white list is
used to enable runtime PM support for only chipset known to work.

Signed-off-by: Zheng Yan <zheng.z.yan@intel.com>
Signed-off-by: Huang Ying <ying.huang@intel.com>
---
 drivers/pci/pci.c              |    9 +++++++++
 drivers/pci/pcie/portdrv_pci.c |   40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)

--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1476,6 +1476,15 @@ bool pci_check_pme_status(struct pci_dev
  */
 static int pci_pme_wakeup(struct pci_dev *dev, void *pme_poll_reset)
 {
+	struct pci_dev *bridge = dev->bus->self;
+
+	/*
+	 * If bridge is in low power state, the configuration space of
+	 * subordinate devices may be not accessible
+	 */
+	if (bridge && bridge->current_state != PCI_D0)
+		return 0;
+
 	if (pme_poll_reset && dev->pme_poll)
 		dev->pme_poll = false;
 
--- a/drivers/pci/pcie/portdrv_pci.c
+++ b/drivers/pci/pcie/portdrv_pci.c
@@ -11,6 +11,7 @@
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/pm.h>
+#include <linux/pm_runtime.h>
 #include <linux/init.h>
 #include <linux/pcieport_if.h>
 #include <linux/aer.h>
@@ -99,6 +100,27 @@ static int pcie_port_resume_noirq(struct
 	return 0;
 }
 
+#ifdef CONFIG_PM_RUNTIME
+static int pcie_port_runtime_suspend(struct device *dev)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+
+	pci_save_state(pdev);
+	return 0;
+}
+
+static int pcie_port_runtime_resume(struct device *dev)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+
+	pci_restore_state(pdev);
+	return 0;
+}
+#else
+#define pcie_port_runtime_suspend	NULL
+#define pcie_port_runtime_resume	NULL
+#endif
+
 static const struct dev_pm_ops pcie_portdrv_pm_ops = {
 	.suspend	= pcie_port_device_suspend,
 	.resume		= pcie_port_device_resume,
@@ -107,6 +129,8 @@ static const struct dev_pm_ops pcie_port
 	.poweroff	= pcie_port_device_suspend,
 	.restore	= pcie_port_device_resume,
 	.resume_noirq	= pcie_port_resume_noirq,
+	.runtime_suspend = pcie_port_runtime_suspend,
+	.runtime_resume = pcie_port_runtime_resume,
 };
 
 #define PCIE_PORTDRV_PM_OPS	(&pcie_portdrv_pm_ops)
@@ -117,6 +141,18 @@ static const struct dev_pm_ops pcie_port
 #endif /* !PM */
 
 /*
+ * PCIe port runtime suspend is broken for some chipset, so use a
+ * white list to disable runtime PM for these chipset.
+ */
+static const struct pci_device_id port_runtime_pm_pci_ids[] = {
+	{ PCI_VDEVICE(INTEL, 0x1e10), },
+	{ PCI_VDEVICE(INTEL, 0x1e16), },
+	{ PCI_VDEVICE(INTEL, 0x1e18), },
+	{ PCI_VDEVICE(INTEL, 0x1e1c), },
+	{ /* end: all zeroes */ }
+};
+
+/*
  * pcie_portdrv_probe - Probe PCI-Express port devices
  * @dev: PCI-Express port device being probed
  *
@@ -144,12 +180,16 @@ static int __devinit pcie_portdrv_probe(
 		return status;
 
 	pci_save_state(dev);
+	if (pci_match_id(port_runtime_pm_pci_ids, dev))
+		pm_runtime_put_noidle(&dev->dev);
 
 	return 0;
 }
 
 static void pcie_portdrv_remove(struct pci_dev *dev)
 {
+	if (pci_match_id(port_runtime_pm_pci_ids, dev))
+		pm_runtime_get_noresume(&dev->dev);
 	pcie_port_device_remove(dev);
 	pci_disable_device(dev);
 }