linux-kernel - [PATCH RFC v1 1/3] PCI: endpoint: Add wakeup host API to EPC core

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Date:   Wed, 14 Jun 2023 20:30:47 +0530
From:   Krishna chaitanya chundru <quic_krichai@...cinc.com>
To:     manivannan.sadhasivam@...aro.org
Cc:     quic_vbadigan@...cinc.com, quic_ramkri@...cinc.com,
        linux-arm-msm@...r.kernel.org, konrad.dybcio@...aro.org,
        Krishna chaitanya chundru <quic_krichai@...cinc.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        linux-pci@...r.kernel.org (open list:PCI ENDPOINT SUBSYSTEM),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH RFC v1 1/3] PCI: endpoint: Add wakeup host API to EPC core

Endpoint cannot send any data/MSI when the device state is in
D3cold or D3hot. Endpoint needs to bring the device back to D0
to send any kind of data.

For this endpoint can send inband PME the device is in D3hot or
toggle wake when the device is D3 cold.

To support this adding wake up host to epc core.

Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
---
 drivers/pci/endpoint/pci-epc-core.c | 29 +++++++++++++++++++++++++++++
 include/linux/pci-epc.h             |  3 +++
 2 files changed, 32 insertions(+)

diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index 46c9a5c..d203947 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -167,6 +167,35 @@ const struct pci_epc_features *pci_epc_get_features(struct pci_epc *epc,
 EXPORT_SYMBOL_GPL(pci_epc_get_features);
 
 /**
+ * pci_epc_wakeup_host() - interrupt the host system
+ * @epc: the EPC device which has to interrupt the host
+ * @func_no: the physical endpoint function number in the EPC device
+ * @vfunc_no: the virtual endpoint function number in the physical function
+ *
+ * Invoke to wakeup host
+ */
+int pci_epc_wakeup_host(struct pci_epc *epc, u8 func_no, u8 vfunc_no)
+{
+	int ret;
+
+	if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions)
+		return -EINVAL;
+
+	if (vfunc_no > 0 && (!epc->max_vfs || vfunc_no > epc->max_vfs[func_no]))
+		return -EINVAL;
+
+	if (!epc->ops->wakeup_host)
+		return 0;
+
+	mutex_lock(&epc->lock);
+	ret = epc->ops->wakeup_host(epc, func_no, vfunc_no);
+	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 301bb0e..a8496be 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -59,6 +59,7 @@ 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 +89,7 @@ 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);
+	int	(*wakeup_host)(struct pci_epc *epc, u8 func_no, u8 vfunc_no);
 	struct module *owner;
 };
 
@@ -232,6 +234,7 @@ 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);
+int pci_epc_wakeup_host(struct pci_epc *epc, u8 func_no, u8 vfunc_no);
 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