[PATCH 1/5] PCI: endpoint: Add linkdown notifier support

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

Add support to notify the EPF device about the linkdown event from the
EPC device.

Usage:
======

EPC
---

```
static irqreturn_t pcie_ep_irq(int irq, void *data)
{
...
	case PCIE_EP_INT_LINK_DOWN:
		pci_epc_linkdown(epc);
		break;
...
}
```

EPF
---

```
static int pci_epf_notifier(struct notifier_block *nb, unsigned long val,
			    void *data)
{
...
	case LINK_DOWN:
		/* Handle link down event */
		break;
...
}
```

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
 drivers/pci/endpoint/pci-epc-core.c | 17 +++++++++++++++++
 include/linux/pci-epc.h             |  1 +
 include/linux/pci-epf.h             |  1 +
 3 files changed, 19 insertions(+)

diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index adec9bee72cf..f29d78c18438 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -641,6 +641,23 @@ void pci_epc_linkup(struct pci_epc *epc)
 }
 EXPORT_SYMBOL_GPL(pci_epc_linkup);
 
+/**
+ * pci_epc_linkdown() - Notify the EPF device that EPC device has dropped the
+ *			connection with the Root Complex.
+ * @epc: the EPC device which has dropped the link with the host
+ *
+ * Invoke to Notify the EPF device that the EPC device has dropped the
+ * connection with the Root Complex.
+ */
+void pci_epc_linkdown(struct pci_epc *epc)
+{
+	if (!epc || IS_ERR(epc))
+		return;
+
+	atomic_notifier_call_chain(&epc->notifier, LINK_DOWN, NULL);
+}
+EXPORT_SYMBOL_GPL(pci_epc_linkdown);
+
 /**
  * pci_epc_init_notify() - Notify the EPF device that EPC device's core
  *			   initialization is completed.
diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index b82c9b100e97..23590efc13e7 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -202,6 +202,7 @@ void pci_epc_destroy(struct pci_epc *epc);
 int pci_epc_add_epf(struct pci_epc *epc, struct pci_epf *epf,
 		    enum pci_epc_interface_type type);
 void pci_epc_linkup(struct pci_epc *epc);
+void pci_epc_linkdown(struct pci_epc *epc);
 void pci_epc_init_notify(struct pci_epc *epc);
 void pci_epc_remove_epf(struct pci_epc *epc, struct pci_epf *epf,
 			enum pci_epc_interface_type type);
diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
index 6833e2160ef1..e9ad634b1575 100644
--- a/include/linux/pci-epf.h
+++ b/include/linux/pci-epf.h
@@ -20,6 +20,7 @@ enum pci_epc_interface_type;
 enum pci_notify_event {
 	CORE_INIT,
 	LINK_UP,
+	LINK_DOWN,
 };
 
 enum pci_barno {
-- 
2.25.1