[PATCH v6 0/3] PCI: designware-ep: Fix DBI access before core init

[PATCH v6 0/3] PCI: designware-ep: Fix DBI access before core init

[Manivannan Sadhasivam]

Hello,

This series is the continuation of previous work by Vidya Sagar [1] to fix the
issues related to accessing DBI register space before completing the core
initialization in some EP platforms like Tegra194/234 and Qcom SM8450.

Since Vidya is busy with other work and didn't respond to my queries [2], I took
the previous series, rebased it on top of pci/next (6e2fca71e187), removed
ep_init_late() callback as it is no longer necessary and posted v6.

I've also kept the Ack given by Jingoo Han for patch 1/3 as there is no drastic
change.

Testing
=======

I've tested the series on Qcom SM8450 based dev board. I also expect it to work
on Tegra platforms as well but it'd be good if Vidya or someone could test it.

- Mani

[1] https://lore.kernel.org/linux-pci/20221013175712.7539-1-vidyas@nvidia.com/
[2] https://lore.kernel.org/linux-pci/20230825123843.GD6005@thinkpad/

Changes in v6:

- Rebased on top of pci/next (6e2fca71e187)
- removed ep_init_late() callback as it is no longer necessary

For previous changelog, please refer [1].

Vidya Sagar (3):
  PCI: designware-ep: Fix DBI access before core init
  PCI: qcom-ep: Refactor EP initialization completion
  PCI: tegra194: Refactor EP initialization completion

 .../pci/controller/dwc/pcie-designware-ep.c   | 142 +++++++++++-------
 drivers/pci/controller/dwc/pcie-designware.h  |   9 +-
 drivers/pci/controller/dwc/pcie-qcom-ep.c     |   4 +-
 drivers/pci/controller/dwc/pcie-tegra194.c    |   4 +-
 4 files changed, 89 insertions(+), 70 deletions(-)


base-commit: 6e2fca71e187932281c7bf4faed1b40e6d9627d6
-- 
2.25.1

[PATCH v6 1/3] PCI: designware-ep: Fix DBI access before core init

[Manivannan Sadhasivam]

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

[PATCH v6 2/3] PCI: qcom-ep: Refactor EP initialization completion

[Manivannan Sadhasivam]

From: Vidya Sagar <vidyas@nvidia.com>

Instead of doing the initialization complete and notifying it to the EPF
drivers at two different places, let's call the dw_pcie_ep_init_notify()
function that takes care of both.

Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
[mani: removed ep_init_late() callback and modified commit message]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
 drivers/pci/controller/dwc/pcie-qcom-ep.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index 32c8d9e37876..3d5196291192 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -447,7 +447,7 @@ static int qcom_pcie_perst_deassert(struct dw_pcie *pci)
 	      PARF_INT_ALL_LINK_UP | PARF_INT_ALL_EDMA;
 	writel_relaxed(val, pcie_ep->parf + PARF_INT_ALL_MASK);
 
-	ret = dw_pcie_ep_init_complete(&pcie_ep->pci.ep);
+	ret = dw_pcie_ep_init_notify(&pcie_ep->pci.ep);
 	if (ret) {
 		dev_err(dev, "Failed to complete initialization: %d\n", ret);
 		goto err_disable_resources;
@@ -466,8 +466,6 @@ static int qcom_pcie_perst_deassert(struct dw_pcie *pci)
 	val &= ~PARF_MSTR_AXI_CLK_EN;
 	writel_relaxed(val, pcie_ep->parf + PARF_MHI_CLOCK_RESET_CTRL);
 
-	dw_pcie_ep_init_notify(&pcie_ep->pci.ep);
-
 	/* Enable LTSSM */
 	val = readl_relaxed(pcie_ep->parf + PARF_LTSSM);
 	val |= BIT(8);
-- 
2.25.1

[PATCH v6 3/3] PCI: tegra194: Refactor EP initialization completion

[Manivannan Sadhasivam]

From: Vidya Sagar <vidyas@nvidia.com>

Instead of doing the initialization complete and notifying it to the EPF
drivers separately, let's call the dw_pcie_ep_init_notify() function that
takes care of both.

Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
[mani: modified the commit message]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
 drivers/pci/controller/dwc/pcie-tegra194.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index a962f2c7794f..a8835287fc3a 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -1897,14 +1897,12 @@ static void pex_ep_event_pex_rst_deassert(struct tegra_pcie_dw *pcie)
 	val = (upper_32_bits(ep->msi_mem_phys) & MSIX_ADDR_MATCH_HIGH_OFF_MASK);
 	dw_pcie_writel_dbi(pci, MSIX_ADDR_MATCH_HIGH_OFF, val);
 
-	ret = dw_pcie_ep_init_complete(ep);
+	ret = dw_pcie_ep_init_notify(ep);
 	if (ret) {
 		dev_err(dev, "Failed to complete initialization: %d\n", ret);
 		goto fail_init_complete;
 	}
 
-	dw_pcie_ep_init_notify(ep);
-
 	/* Program the private control to allow sending LTR upstream */
 	if (pcie->of_data->has_ltr_req_fix) {
 		val = appl_readl(pcie, APPL_LTR_MSG_2);
-- 
2.25.1