diff mbox series

[v3,4/5] PCI: host-common: Add link down handling for host bridges

Message ID 20250417-pcie-reset-slot-v3-4-59a10811c962@linaro.org
State New
Headers show
Series PCI: Add support for resetting the slots in a platform specific way | expand

Commit Message

Manivannan Sadhasivam via B4 Relay April 17, 2025, 5:16 p.m. UTC 
From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

The PCI link, when down, needs to be recovered to bring it back. But that
cannot be done in a generic way as link recovery procedure is specific to
host bridges. So add a new API pci_host_handle_link_down() that could be
called by the host bridge drivers when the link goes down.

The API will iterate through all the slots and calls the pcie_do_recovery()
function with 'pci_channel_io_frozen' as the state. This will result in the
execution of the AER Fatal error handling code. Since the link down
recovery is pretty much the same as AER Fatal error handling,
pcie_do_recovery() helper is reused here. First the AER error_detected
callback will be triggered for the bridge and the downstream devices. Then,
pci_host_reset_slot() will be called for the slot, which will reset the
slot using 'reset_slot' callback to recover the link. Once that's done,
resume message will be broadcasted to the bridge and the downstream devices
indicating successful link recovery.

In case if the AER support is not enabled in the kernel, only
pci_bus_error_reset() will be called for each slots as there is no way we
could inform the drivers about link recovery.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
 drivers/pci/controller/pci-host-common.c | 58 ++++++++++++++++++++++++++++++++
 drivers/pci/controller/pci-host-common.h |  1 +
 drivers/pci/pci.c                        |  1 +
 drivers/pci/pcie/err.c                   |  1 +
 4 files changed, 61 insertions(+)
diff mbox series

Patch

diff --git a/drivers/pci/controller/pci-host-common.c b/drivers/pci/controller/pci-host-common.c
index f93bc7034e697250711833a5151f7ef177cd62a0..f916f0a874a61ddfbfd99f96975c00fb66dd224c 100644
--- a/drivers/pci/controller/pci-host-common.c
+++ b/drivers/pci/controller/pci-host-common.c
@@ -12,9 +12,11 @@ 
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_pci.h>
+#include <linux/pci.h>
 #include <linux/pci-ecam.h>
 #include <linux/platform_device.h>
 
+#include "../pci.h"
 #include "pci-host-common.h"
 
 static void gen_pci_unmap_cfg(void *ptr)
@@ -96,5 +98,61 @@  void pci_host_common_remove(struct platform_device *pdev)
 }
 EXPORT_SYMBOL_GPL(pci_host_common_remove);
 
+#if IS_ENABLED(CONFIG_PCIEAER)
+static pci_ers_result_t pci_host_reset_slot(struct pci_dev *dev)
+{
+	int ret;
+
+	ret = pci_bus_error_reset(dev);
+	if (ret) {
+		pci_err(dev, "Failed to reset slot: %d\n", ret);
+		return PCI_ERS_RESULT_DISCONNECT;
+	}
+
+	pci_info(dev, "Slot has been reset\n");
+
+	return PCI_ERS_RESULT_RECOVERED;
+}
+
+static void pci_host_recover_slots(struct pci_host_bridge *host)
+{
+	struct pci_bus *bus = host->bus;
+	struct pci_dev *dev;
+
+	for_each_pci_bridge(dev, bus) {
+		if (!pci_is_root_bus(bus))
+			continue;
+
+		pcie_do_recovery(dev, pci_channel_io_frozen,
+				 pci_host_reset_slot);
+	}
+}
+#else
+static void pci_host_recover_slots(struct pci_host_bridge *host)
+{
+	struct pci_bus *bus = host->bus;
+	struct pci_dev *dev;
+	int ret;
+
+	for_each_pci_bridge(dev, bus) {
+		if (!pci_is_root_bus(bus))
+			continue;
+
+		ret = pci_bus_error_reset(dev);
+		if (ret)
+			pci_err(dev, "Failed to reset slot: %d\n", ret);
+		else
+			pci_info(dev, "Slot has been reset\n");
+	}
+}
+#endif
+
+void pci_host_handle_link_down(struct pci_host_bridge *bridge)
+{
+	dev_info(&bridge->dev, "Recovering slots due to Link Down\n");
+	pci_host_recover_slots(bridge);
+}
+EXPORT_SYMBOL_GPL(pci_host_handle_link_down);
+
 MODULE_DESCRIPTION("Common library for PCI host controller drivers");
 MODULE_LICENSE("GPL v2");
diff --git a/drivers/pci/controller/pci-host-common.h b/drivers/pci/controller/pci-host-common.h
index 30253ff26e01fb445ecf67b795209e6d0a9ec7c4..f5d05d6c761ffea551c670f9af2cea870a8c2daa 100644
--- a/drivers/pci/controller/pci-host-common.h
+++ b/drivers/pci/controller/pci-host-common.h
@@ -12,5 +12,6 @@ 
 
 int pci_host_common_probe(struct platform_device *pdev);
 void pci_host_common_remove(struct platform_device *pdev);
+void pci_host_handle_link_down(struct pci_host_bridge *bridge);
 
 #endif
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 13709bb898a967968540826a2b7ee8ade6b7e082..4d396bbab4a8f33cae0ffe8982da120a9f1d92c9 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5781,6 +5781,7 @@  int pci_bus_error_reset(struct pci_dev *bridge)
 	mutex_unlock(&pci_slot_mutex);
 	return pci_bus_reset(bridge->subordinate, PCI_RESET_DO_RESET);
 }
+EXPORT_SYMBOL_GPL(pci_bus_error_reset);
 
 /**
  * pci_probe_reset_bus - probe whether a PCI bus can be reset
diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index b834fc0d705938540d3d7d3d8739770c09fe7cf1..3e3084bb7cb7fa06b526e6fab60e77927aba0ad0 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -270,3 +270,4 @@  pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
 
 	return status;
 }
+EXPORT_SYMBOL_GPL(pcie_do_recovery);