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From:   Vidya Sagar <vidyas@nvidia.com>
To:     <jingoohan1@gmail.com>, <gustavo.pimentel@synopsys.com>,
        <lpieralisi@kernel.org>, <robh@kernel.org>, <kw@linux.com>,
        <bhelgaas@google.com>, <mani@kernel.org>,
        <Sergey.Semin@baikalelectronics.ru>, <dmitry.baryshkov@linaro.org>,
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CC:     <thierry.reding@gmail.com>, <jonathanh@nvidia.com>,
        <linux-pci@vger.kernel.org>, <linux-arm-msm@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <kthota@nvidia.com>,
        <mmaddireddy@nvidia.com>, <vidyas@nvidia.com>, <sagar.tv@gmail.com>
Subject: [PATCH V4 1/3] PCI: designware-ep: Fix DBI access before core init
Date:   Tue, 20 Sep 2022 00:03:40 +0530
Message-ID: <20220919183342.4090-2-vidyas@nvidia.com>
In-Reply-To: <20220919183342.4090-1-vidyas@nvidia.com>
References: <20220919183342.4090-1-vidyas@nvidia.com>
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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.

Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
---
V4:
* Addressed review comments from Bjorn and Manivannan
* Moved dw_pcie_ep_init_complete() inside dw_pcie_ep_init_notify()
* Added .ep_init_late() ops to perform late init tasks

 .../pci/controller/dwc/pcie-designware-ep.c   | 112 ++++++++++--------
 drivers/pci/controller/dwc/pcie-designware.h  |  10 +-
 2 files changed, 68 insertions(+), 54 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 83ddb190292e..095fb0291ec9 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -23,14 +23,6 @@ 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)
 {
@@ -640,12 +632,17 @@ 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_complete(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;
 	unsigned int nbars;
 	u8 hdr_type;
+	u8 func_no;
+	void *addr;
 	u32 reg;
 	int i;
 
@@ -658,6 +655,40 @@ int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
 		return -EIO;
 	}
 
+	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;
+
+	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);
+	}
+
 	offset = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_REBAR);
 
 	dw_pcie_dbi_ro_wr_en(pci);
@@ -676,13 +707,28 @@ int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
 
 	return 0;
 }
-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_complete(ep);
+	if (ret)
+		return ret;
+
+	if (ep->ops->ep_init_late)
+		ep->ops->ep_init_late(ep);
+
+	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);
@@ -690,7 +736,6 @@ 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);
 
@@ -719,26 +764,6 @@ 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;
-
 	if (pci->link_gen < 1)
 		pci->link_gen = of_pci_get_max_link_speed(np);
 
@@ -755,20 +780,6 @@ 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);
 
@@ -793,6 +804,13 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
 			return 0;
 	}
 
+	/*
+	 * 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_complete(ep);
 	if (ret)
 		goto err_free_epc_mem;
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 09b887093a84..7222717afa33 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -254,6 +254,7 @@ struct dw_pcie_rp {
 
 struct dw_pcie_ep_ops {
 	void	(*ep_init)(struct dw_pcie_ep *ep);
+	void	(*ep_init_late)(struct dw_pcie_ep *ep);
 	int	(*raise_irq)(struct dw_pcie_ep *ep, u8 func_no,
 			     enum pci_epc_irq_type type, u16 interrupt_num);
 	const struct pci_epc_features* (*get_features)(struct dw_pcie_ep *ep);
@@ -467,8 +468,7 @@ 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,
@@ -490,15 +490,11 @@ 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)
 {
 }
-- 
2.17.1