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

Krishna Chaitanya Chundru
2025-02-25T09:35:13Z

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@oss.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