PCI: endpoint: Introduce 'epc_deinit' event and notify the EPF drivers

As like the 'epc_init' event, that is used to signal the EPF drivers about
the EPC initialization, let's introduce 'epc_deinit' event that is used to
signal EPC deinitialization.

The EPC deinitialization applies only when any sort of fundamental reset
is supported by the endpoint controller as per the PCIe spec.

Reference: PCIe r6.0, sec 4.2.5.9.1 and 6.6.1.

Currently, some EPC drivers like pcie-qcom-ep and pcie-tegra194 support
PERST# as the fundamental reset. So the 'deinit' event will be notified to
the EPF drivers when PERST# assert happens in the above mentioned EPC
drivers.

The EPF drivers, on receiving the event through the epc_deinit() callback
should reset the EPF state machine and also cleanup any configuration that
got affected by the fundamental reset like BAR, DMA etc...

This change also warrants skipping the cleanups in unbind() if already done
in epc_deinit().

Link: https://lore.kernel.org/r/20240606-pci-deinit-v1-2-4395534520dc@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>

6 files changed, 61 insertions, 3 deletions

diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 47391d7d3a73..2063cf2049e5 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -632,7 +632,6 @@ void dw_pcie_ep_cleanup(struct dw_pcie_ep *ep)
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
 
 	dw_pcie_edma_remove(pci);
-	ep->epc->init_complete = false;
 }
 EXPORT_SYMBOL_GPL(dw_pcie_ep_cleanup);
 
diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index 1ecf602c225a..b6a5010cc1a7 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -507,6 +507,7 @@ static void qcom_pcie_perst_assert(struct dw_pcie *pci)
 		return;
 	}
 
+	pci_epc_deinit_notify(pci->ep.epc);
 	dw_pcie_ep_cleanup(&pci->ep);
 	qcom_pcie_disable_resources(pcie_ep);
 	pcie_ep->link_status = QCOM_PCIE_EP_LINK_DISABLED;
diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index 93f5433c5c55..4b28f8beedfe 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -1715,6 +1715,7 @@ static void pex_ep_event_pex_rst_assert(struct tegra_pcie_dw *pcie)
 	if (ret)
 		dev_err(pcie->dev, "Failed to go Detect state: %d\n", ret);
 
+	pci_epc_deinit_notify(pcie->pci.ep.epc);
 	dw_pcie_ep_cleanup(&pcie->pci.ep);
 
 	reset_control_assert(pcie->core_rst);
diff --git a/drivers/pci/endpoint/functions/pci-epf-mhi.c b/drivers/pci/endpoint/functions/pci-epf-mhi.c
index 205c02953f25..5832989e55e8 100644
--- a/drivers/pci/endpoint/functions/pci-epf-mhi.c
+++ b/drivers/pci/endpoint/functions/pci-epf-mhi.c
@@ -764,6 +764,24 @@ static int pci_epf_mhi_epc_init(struct pci_epf *epf)
 	return 0;
 }
 
+static void pci_epf_mhi_epc_deinit(struct pci_epf *epf)
+{
+	struct pci_epf_mhi *epf_mhi = epf_get_drvdata(epf);
+	const struct pci_epf_mhi_ep_info *info = epf_mhi->info;
+	struct pci_epf_bar *epf_bar = &epf->bar[info->bar_num];
+	struct mhi_ep_cntrl *mhi_cntrl = &epf_mhi->mhi_cntrl;
+	struct pci_epc *epc = epf->epc;
+
+	if (mhi_cntrl->mhi_dev) {
+		mhi_ep_power_down(mhi_cntrl);
+		if (info->flags & MHI_EPF_USE_DMA)
+			pci_epf_mhi_dma_deinit(epf_mhi);
+		mhi_ep_unregister_controller(mhi_cntrl);
+	}
+
+	pci_epc_clear_bar(epc, epf->func_no, epf->vfunc_no, epf_bar);
+}
+
 static int pci_epf_mhi_link_up(struct pci_epf *epf)
 {
 	struct pci_epf_mhi *epf_mhi = epf_get_drvdata(epf);
@@ -898,6 +916,7 @@ static void pci_epf_mhi_unbind(struct pci_epf *epf)
 
 static const struct pci_epc_event_ops pci_epf_mhi_event_ops = {
 	.epc_init = pci_epf_mhi_epc_init,
+	.epc_deinit = pci_epf_mhi_epc_deinit,
 	.link_up = pci_epf_mhi_link_up,
 	.link_down = pci_epf_mhi_link_down,
 	.bus_master_enable = pci_epf_mhi_bus_master_enable,
diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index e771be7512a1..7c2ed6eae53a 100644
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -782,6 +782,15 @@ static int pci_epf_test_epc_init(struct pci_epf *epf)
 	return 0;
 }
 
+static void pci_epf_test_epc_deinit(struct pci_epf *epf)
+{
+	struct pci_epf_test *epf_test = epf_get_drvdata(epf);
+
+	cancel_delayed_work(&epf_test->cmd_handler);
+	pci_epf_test_clean_dma_chan(epf_test);
+	pci_epf_test_clear_bar(epf);
+}
+
 static int pci_epf_test_link_up(struct pci_epf *epf)
 {
 	struct pci_epf_test *epf_test = epf_get_drvdata(epf);
@@ -803,6 +812,7 @@ static int pci_epf_test_link_down(struct pci_epf *epf)
 
 static const struct pci_epc_event_ops pci_epf_test_event_ops = {
 	.epc_init = pci_epf_test_epc_init,
+	.epc_deinit = pci_epf_test_epc_deinit,
 	.link_up = pci_epf_test_link_up,
 	.link_down = pci_epf_test_link_down,
 };
@@ -905,10 +915,13 @@ static int pci_epf_test_bind(struct pci_epf *epf)
 static void pci_epf_test_unbind(struct pci_epf *epf)
 {
 	struct pci_epf_test *epf_test = epf_get_drvdata(epf);
+	struct pci_epc *epc = epf->epc;
 
 	cancel_delayed_work(&epf_test->cmd_handler);
-	pci_epf_test_clean_dma_chan(epf_test);
-	pci_epf_test_clear_bar(epf);
+	if (epc->init_complete) {
+		pci_epf_test_clean_dma_chan(epf_test);
+		pci_epf_test_clear_bar(epf);
+	}
 	pci_epf_test_free_space(epf);
 }
 
diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index 56b60330355d..47a91dcb07d7 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -775,6 +775,31 @@ void pci_epc_notify_pending_init(struct pci_epc *epc, struct pci_epf *epf)
 EXPORT_SYMBOL_GPL(pci_epc_notify_pending_init);
 
 /**
+ * pci_epc_deinit_notify() - Notify the EPF device about EPC deinitialization
+ * @epc: the EPC device whose deinitialization is completed
+ *
+ * Invoke to notify the EPF device that the EPC deinitialization is completed.
+ */
+void pci_epc_deinit_notify(struct pci_epc *epc)
+{
+	struct pci_epf *epf;
+
+	if (IS_ERR_OR_NULL(epc))
+		return;
+
+	mutex_lock(&epc->list_lock);
+	list_for_each_entry(epf, &epc->pci_epf, list) {
+		mutex_lock(&epf->lock);
+		if (epf->event_ops && epf->event_ops->epc_deinit)
+			epf->event_ops->epc_deinit(epf);
+		mutex_unlock(&epf->lock);
+	}
+	epc->init_complete = false;
+	mutex_unlock(&epc->list_lock);
+}
+EXPORT_SYMBOL_GPL(pci_epc_deinit_notify);
+
+/**
  * pci_epc_bus_master_enable_notify() - Notify the EPF device that the EPC
  *					device has received the Bus Master
  *					Enable event from the Root complex