linux-kernel - [PATCH v4 07/10] PCI: PCI: Add pcie_is_link_active() to determine if the PCIe link is active

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Message-Id: <20250225-qps615_v4_1-v4-7-e08633a7bdf8@oss.qualcomm.com>
Date: Tue, 25 Feb 2025 15:04:04 +0530
From: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
To: Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        chaitanya chundru <quic_krichai@...cinc.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        cros-qcom-dts-watchers@...omium.org, Jingoo Han <jingoohan1@...il.com>,
        Bartosz Golaszewski <brgl@...ev.pl>
Cc: quic_vbadigan@...cnic.com, amitk@...nel.org, dmitry.baryshkov@...aro.org,
        linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        jorge.ramirez@....qualcomm.com,
        Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Subject: [PATCH v4 07/10] PCI: PCI: Add pcie_is_link_active() to determine
 if the PCIe link is active

Introduce a common API to check if the PCIe link is active, replacing
duplicate code in multiple locations.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
---
 drivers/pci/hotplug/pciehp_hpc.c | 13 +------------
 drivers/pci/pci.c                | 26 +++++++++++++++++++++++---
 include/linux/pci.h              |  5 +++++
 3 files changed, 29 insertions(+), 15 deletions(-)

diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index bb5a8d9f03ad..d0a2efebb519 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -234,18 +234,7 @@ static void pcie_write_cmd_nowait(struct controller *ctrl, u16 cmd, u16 mask)
  */
 int pciehp_check_link_active(struct controller *ctrl)
 {
-	struct pci_dev *pdev = ctrl_dev(ctrl);
-	u16 lnk_status;
-	int ret;
-
-	ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
-	if (ret == PCIBIOS_DEVICE_NOT_FOUND || PCI_POSSIBLE_ERROR(lnk_status))
-		return -ENODEV;
-
-	ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA);
-	ctrl_dbg(ctrl, "%s: lnk_status = %x\n", __func__, lnk_status);
-
-	return ret;
+	return pcie_is_link_active(ctrl_dev(ctrl));
 }
 
 static bool pci_bus_check_dev(struct pci_bus *bus, int devfn)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 869d204a70a3..3d4fe6fefa13 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4907,7 +4907,6 @@ int pci_bridge_wait_for_secondary_bus(struct pci_dev *dev, char *reset_type)
 		return 0;
 
 	if (pcie_get_speed_cap(dev) <= PCIE_SPEED_5_0GT) {
-		u16 status;
 
 		pci_dbg(dev, "waiting %d ms for downstream link\n", delay);
 		msleep(delay);
@@ -4923,8 +4922,7 @@ int pci_bridge_wait_for_secondary_bus(struct pci_dev *dev, char *reset_type)
 		if (!dev->link_active_reporting)
 			return -ENOTTY;
 
-		pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &status);
-		if (!(status & PCI_EXP_LNKSTA_DLLLA))
+		if (pcie_is_link_active(dev))
 			return -ENOTTY;
 
 		return pci_dev_wait(child, reset_type,
@@ -6219,6 +6217,28 @@ void pcie_print_link_status(struct pci_dev *dev)
 }
 EXPORT_SYMBOL(pcie_print_link_status);
 
+/**
+ * pcie_is_link_active() - Checks if the link is active or not
+ * @pdev: PCI device to query
+ *
+ * Check whether the link is active or not.
+ *
+ * If the config read returns error then return -ENODEV.
+ */
+int pcie_is_link_active(struct pci_dev *pdev)
+{
+	u16 lnk_status;
+	int ret;
+
+	ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
+	if (ret == PCIBIOS_DEVICE_NOT_FOUND || PCI_POSSIBLE_ERROR(lnk_status))
+		return -ENODEV;
+
+	pci_dbg(pdev, "lnk_status = %x\n", lnk_status);
+	return !!(lnk_status & PCI_EXP_LNKSTA_DLLLA);
+}
+EXPORT_SYMBOL(pcie_is_link_active);
+
 /**
  * pci_select_bars - Make BAR mask from the type of resource
  * @dev: the PCI device for which BAR mask is made
diff --git a/include/linux/pci.h b/include/linux/pci.h
index bbec32be668b..84bb98e61e8a 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1946,6 +1946,7 @@ pci_release_mem_regions(struct pci_dev *pdev)
 			    pci_select_bars(pdev, IORESOURCE_MEM));
 }
 
+int pcie_is_link_active(struct pci_dev *dev);
 #else /* CONFIG_PCI is not enabled */
 
 static inline void pci_set_flags(int flags) { }
@@ -2094,6 +2095,10 @@ pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
 {
 	return -ENOSPC;
 }
+
+static inline int pcie_is_link_active(struct pci_dev *dev)
+{ return -ENODEV; }
+
 #endif /* CONFIG_PCI */
 
 /* Include architecture-dependent settings and functions */

-- 
2.34.1