[PATCH v4 5/9] PCI: endpoint: Add wakeup host API to EPC core

[Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>]

Endpoint cannot send any data/MSI when the D-state is in
D3cold or D3hot. Endpoint needs to wake up the host to
bring the D-state to D0.

Endpoint can toggle wake signal when the D-state is in D3cold and vaux is
not supplied or can send inband PME.

To support this add wakeup_host() callback to the EPC core.

Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
---
 Documentation/PCI/endpoint/pci-endpoint.rst |  6 ++++++
 drivers/pci/endpoint/pci-epc-core.c         | 31 +++++++++++++++++++++++++++++
 include/linux/pci-epc.h                     | 11 ++++++++++
 3 files changed, 48 insertions(+)

diff --git a/Documentation/PCI/endpoint/pci-endpoint.rst b/Documentation/PCI/endpoint/pci-endpoint.rst
index 3a54713..eb79b77 100644
--- a/Documentation/PCI/endpoint/pci-endpoint.rst
+++ b/Documentation/PCI/endpoint/pci-endpoint.rst
@@ -53,6 +53,7 @@ by the PCI controller driver.
 	 * raise_irq: ops to raise a legacy, MSI or MSI-X interrupt
 	 * start: ops to start the PCI link
 	 * stop: ops to stop the PCI link
+	 * wakeup_host: ops to wakeup host
 
    The PCI controller driver can then create a new EPC device by invoking
    devm_pci_epc_create()/pci_epc_create().
@@ -122,6 +123,11 @@ by the PCI endpoint function driver.
    The PCI endpoint function driver should use pci_epc_mem_free_addr() to
    free the memory space allocated using pci_epc_mem_alloc_addr().
 
+* pci_epc_wakeup_host()
+
+   The PCI endpoint function driver should use pci_epc_wakeup_host() to wakeup
+   host.
+
 Other EPC APIs
 ~~~~~~~~~~~~~~
 
diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index ea76baf..b419eff 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -167,6 +167,37 @@ const struct pci_epc_features *pci_epc_get_features(struct pci_epc *epc,
 EXPORT_SYMBOL_GPL(pci_epc_get_features);
 
 /**
+ * pci_epc_wakeup_host() - Wakeup the host
+ * @epc: the EPC device which has to wakeup the host
+ * @func_no: the physical endpoint function number in the EPC device
+ * @vfunc_no: the virtual endpoint function number in the physical function
+ * @type: specify the type of wakeup: WAKEUP_FROM_D3COLD, WAKEUP_FROM_D3HOT
+ *
+ * Invoke to wakeup host
+ */
+bool pci_epc_wakeup_host(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+			enum pci_epc_wakeup_host_type type)
+{
+	int ret;
+
+	if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions)
+		return false;
+
+	if (vfunc_no > 0 && (!epc->max_vfs || vfunc_no > epc->max_vfs[func_no]))
+		return false;
+
+	if (!epc->ops->wakeup_host)
+		return true;
+
+	mutex_lock(&epc->lock);
+	ret = epc->ops->wakeup_host(epc, func_no, vfunc_no, type);
+	mutex_unlock(&epc->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pci_epc_wakeup_host);
+
+/**
  * pci_epc_stop() - stop the PCI link
  * @epc: the link of the EPC device that has to be stopped
  *
diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index 26a1108..d262179 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -26,6 +26,12 @@ enum pci_epc_irq_type {
 	PCI_EPC_IRQ_MSIX,
 };
 
+enum pci_epc_wakeup_host_type {
+	PCI_WAKEUP_UNKNOWN,
+	PCI_WAKEUP_SEND_PME,
+	PCI_WAKEUP_TOGGLE_WAKE,
+};
+
 static inline const char *
 pci_epc_interface_string(enum pci_epc_interface_type type)
 {
@@ -59,6 +65,7 @@ pci_epc_interface_string(enum pci_epc_interface_type type)
  * @start: ops to start the PCI link
  * @stop: ops to stop the PCI link
  * @get_features: ops to get the features supported by the EPC
+ * @wakeup_host: ops to wakeup the host
  * @owner: the module owner containing the ops
  */
 struct pci_epc_ops {
@@ -88,6 +95,8 @@ struct pci_epc_ops {
 	void	(*stop)(struct pci_epc *epc);
 	const struct pci_epc_features* (*get_features)(struct pci_epc *epc,
 						       u8 func_no, u8 vfunc_no);
+	bool	(*wakeup_host)(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+				enum pci_epc_wakeup_host_type type);
 	struct module *owner;
 };
 
@@ -234,6 +243,8 @@ int pci_epc_start(struct pci_epc *epc);
 void pci_epc_stop(struct pci_epc *epc);
 const struct pci_epc_features *pci_epc_get_features(struct pci_epc *epc,
 						    u8 func_no, u8 vfunc_no);
+bool pci_epc_wakeup_host(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+					enum pci_epc_wakeup_host_type type);
 enum pci_barno
 pci_epc_get_first_free_bar(const struct pci_epc_features *epc_features);
 enum pci_barno pci_epc_get_next_free_bar(const struct pci_epc_features
-- 
2.7.4