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From:   Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To:     jingoohan1@gmail.com, gustavo.pimentel@synopsys.com,
        lpieralisi@kernel.org, robh@kernel.org, kw@linux.com,
        bhelgaas@google.com
Cc:     linux-pci@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org, vidyas@nvidia.com,
        Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Subject: [PATCH v6 1/3] PCI: designware-ep: Fix DBI access before core init
Date:   Fri, 20 Oct 2023 12:13:18 +0530
Message-Id: <20231020064320.5302-2-manivannan.sadhasivam@linaro.org>
In-Reply-To: <20231020064320.5302-1-manivannan.sadhasivam@linaro.org>
References: <20231020064320.5302-1-manivannan.sadhasivam@linaro.org>
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From: Vidya Sagar <vidyas@nvidia.com>

Platforms that cannot support their core initialization without the
reference clock from the host, implement the feature 'core_init_notifier'
to indicate the DesignWare sub-system about when their core is getting
initialized. Any accesses to the core (Ex:- DBI) would the core being
ready result in system hang in such systems (Ex:- tegra194).
This patch moves any access to the core to dw_pcie_ep_init_complete() API
which is effectively called only after the core initialization.
It also introduces .ep_init_late() ops hook to be used for any post init
work that platform drivers may have to do.

Acked-by: Jingoo Han <jingoohan1@gmail.com>
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
[mani: rebased and removed ep_init_late() callback]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
 .../pci/controller/dwc/pcie-designware-ep.c   | 142 +++++++++++-------
 drivers/pci/controller/dwc/pcie-designware.h  |   9 +-
 2 files changed, 87 insertions(+), 64 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index f9182f8d552f..f37c4481e7d0 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -21,14 +21,6 @@ void dw_pcie_ep_linkup(struct dw_pcie_ep *ep)
 }
 EXPORT_SYMBOL_GPL(dw_pcie_ep_linkup);
 
-void dw_pcie_ep_init_notify(struct dw_pcie_ep *ep)
-{
-	struct pci_epc *epc = ep->epc;
-
-	pci_epc_init_notify(epc);
-}
-EXPORT_SYMBOL_GPL(dw_pcie_ep_init_notify);
-
 struct dw_pcie_ep_func *
 dw_pcie_ep_get_func_from_ep(struct dw_pcie_ep *ep, u8 func_no)
 {
@@ -641,14 +633,19 @@ static unsigned int dw_pcie_ep_find_ext_capability(struct dw_pcie *pci, int cap)
 	return 0;
 }
 
-int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
+static int dw_pcie_ep_init_late(struct dw_pcie_ep *ep)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
+	struct dw_pcie_ep_func *ep_func;
+	struct device *dev = pci->dev;
+	struct pci_epc *epc = ep->epc;
 	unsigned int offset, ptm_cap_base;
 	unsigned int nbars;
 	u8 hdr_type;
+	u8 func_no;
+	int i, ret;
+	void *addr;
 	u32 reg;
-	int i;
 
 	hdr_type = dw_pcie_readb_dbi(pci, PCI_HEADER_TYPE) &
 		   PCI_HEADER_TYPE_MASK;
@@ -659,6 +656,55 @@ int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
 		return -EIO;
 	}
 
+	dw_pcie_version_detect(pci);
+
+	dw_pcie_iatu_detect(pci);
+
+	ret = dw_pcie_edma_detect(pci);
+	if (ret)
+		return ret;
+
+	if (!ep->ib_window_map) {
+		ep->ib_window_map = devm_bitmap_zalloc(dev, pci->num_ib_windows,
+						       GFP_KERNEL);
+		if (!ep->ib_window_map)
+			goto err_remove_edma;
+	}
+
+	if (!ep->ob_window_map) {
+		ep->ob_window_map = devm_bitmap_zalloc(dev, pci->num_ob_windows,
+						       GFP_KERNEL);
+		if (!ep->ob_window_map)
+			goto err_remove_edma;
+	}
+
+	if (!ep->outbound_addr) {
+		addr = devm_kcalloc(dev, pci->num_ob_windows, sizeof(phys_addr_t),
+				    GFP_KERNEL);
+		if (!addr)
+			goto err_remove_edma;
+		ep->outbound_addr = addr;
+	}
+
+	for (func_no = 0; func_no < epc->max_functions; func_no++) {
+
+		ep_func = dw_pcie_ep_get_func_from_ep(ep, func_no);
+		if (ep_func)
+			continue;
+
+		ep_func = devm_kzalloc(dev, sizeof(*ep_func), GFP_KERNEL);
+		if (!ep_func)
+			goto err_remove_edma;
+
+		ep_func->func_no = func_no;
+		ep_func->msi_cap = dw_pcie_ep_find_capability(ep, func_no,
+							      PCI_CAP_ID_MSI);
+		ep_func->msix_cap = dw_pcie_ep_find_capability(ep, func_no,
+							       PCI_CAP_ID_MSIX);
+
+		list_add_tail(&ep_func->list, &ep->func_list);
+	}
+
 	offset = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_REBAR);
 	ptm_cap_base = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_PTM);
 
@@ -693,14 +739,31 @@ int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
 	dw_pcie_dbi_ro_wr_dis(pci);
 
 	return 0;
+
+err_remove_edma:
+	dw_pcie_edma_remove(pci);
+
+	return ret;
 }
-EXPORT_SYMBOL_GPL(dw_pcie_ep_init_complete);
+
+int dw_pcie_ep_init_notify(struct dw_pcie_ep *ep)
+{
+	struct pci_epc *epc = ep->epc;
+	int ret;
+
+	ret = dw_pcie_ep_init_late(ep);
+	if (ret)
+		return ret;
+
+	pci_epc_init_notify(epc);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dw_pcie_ep_init_notify);
 
 int dw_pcie_ep_init(struct dw_pcie_ep *ep)
 {
 	int ret;
-	void *addr;
-	u8 func_no;
 	struct resource *res;
 	struct pci_epc *epc;
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
@@ -708,7 +771,6 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
 	struct platform_device *pdev = to_platform_device(dev);
 	struct device_node *np = dev->of_node;
 	const struct pci_epc_features *epc_features;
-	struct dw_pcie_ep_func *ep_func;
 
 	INIT_LIST_HEAD(&ep->func_list);
 
@@ -723,26 +785,6 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
 	ep->phys_base = res->start;
 	ep->addr_size = resource_size(res);
 
-	dw_pcie_version_detect(pci);
-
-	dw_pcie_iatu_detect(pci);
-
-	ep->ib_window_map = devm_bitmap_zalloc(dev, pci->num_ib_windows,
-					       GFP_KERNEL);
-	if (!ep->ib_window_map)
-		return -ENOMEM;
-
-	ep->ob_window_map = devm_bitmap_zalloc(dev, pci->num_ob_windows,
-					       GFP_KERNEL);
-	if (!ep->ob_window_map)
-		return -ENOMEM;
-
-	addr = devm_kcalloc(dev, pci->num_ob_windows, sizeof(phys_addr_t),
-			    GFP_KERNEL);
-	if (!addr)
-		return -ENOMEM;
-	ep->outbound_addr = addr;
-
 	epc = devm_pci_epc_create(dev, &epc_ops);
 	if (IS_ERR(epc)) {
 		dev_err(dev, "Failed to create epc device\n");
@@ -756,20 +798,6 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
 	if (ret < 0)
 		epc->max_functions = 1;
 
-	for (func_no = 0; func_no < epc->max_functions; func_no++) {
-		ep_func = devm_kzalloc(dev, sizeof(*ep_func), GFP_KERNEL);
-		if (!ep_func)
-			return -ENOMEM;
-
-		ep_func->func_no = func_no;
-		ep_func->msi_cap = dw_pcie_ep_find_capability(ep, func_no,
-							      PCI_CAP_ID_MSI);
-		ep_func->msix_cap = dw_pcie_ep_find_capability(ep, func_no,
-							       PCI_CAP_ID_MSIX);
-
-		list_add_tail(&ep_func->list, &ep->func_list);
-	}
-
 	if (ep->ops->ep_init)
 		ep->ops->ep_init(ep);
 
@@ -788,25 +816,25 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
 		goto err_exit_epc_mem;
 	}
 
-	ret = dw_pcie_edma_detect(pci);
-	if (ret)
-		goto err_free_epc_mem;
-
 	if (ep->ops->get_features) {
 		epc_features = ep->ops->get_features(ep);
 		if (epc_features->core_init_notifier)
 			return 0;
 	}
 
-	ret = dw_pcie_ep_init_complete(ep);
+	/*
+	 * NOTE:- Avoid accessing the hardware (Ex:- DBI space) before this
+	 * step as platforms that implement 'core_init_notifier' feature may
+	 * not have the hardware ready (i.e. core initialized) for access
+	 * (Ex: tegra194). Any hardware access on such platforms result
+	 * in system hard hang.
+	 */
+	ret = dw_pcie_ep_init_late(ep);
 	if (ret)
-		goto err_remove_edma;
+		goto err_free_epc_mem;
 
 	return 0;
 
-err_remove_edma:
-	dw_pcie_edma_remove(pci);
-
 err_free_epc_mem:
 	pci_epc_mem_free_addr(epc, ep->msi_mem_phys, ep->msi_mem,
 			      epc->mem->window.page_size);
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index efb4d4754fc8..9e8e95df320c 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -573,8 +573,7 @@ static inline void __iomem *dw_pcie_own_conf_map_bus(struct pci_bus *bus,
 #ifdef CONFIG_PCIE_DW_EP
 void dw_pcie_ep_linkup(struct dw_pcie_ep *ep);
 int dw_pcie_ep_init(struct dw_pcie_ep *ep);
-int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep);
-void dw_pcie_ep_init_notify(struct dw_pcie_ep *ep);
+int dw_pcie_ep_init_notify(struct dw_pcie_ep *ep);
 void dw_pcie_ep_exit(struct dw_pcie_ep *ep);
 int dw_pcie_ep_raise_legacy_irq(struct dw_pcie_ep *ep, u8 func_no);
 int dw_pcie_ep_raise_msi_irq(struct dw_pcie_ep *ep, u8 func_no,
@@ -596,15 +595,11 @@ static inline int dw_pcie_ep_init(struct dw_pcie_ep *ep)
 	return 0;
 }
 
-static inline int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
+static inline int dw_pcie_ep_init_notify(struct dw_pcie_ep *ep)
 {
 	return 0;
 }
 
-static inline void dw_pcie_ep_init_notify(struct dw_pcie_ep *ep)
-{
-}
-
 static inline void dw_pcie_ep_exit(struct dw_pcie_ep *ep)
 {
 }
-- 
2.25.1