[PATCH v16 8/9] PCI/DPC: Add Error Disconnect Recover (EDR) support

sathyanarayanan.kuppuswamy
2020-02-28T01:02:57Z

As per ACPI specification r6.3, sec 5.6.6, when firmware owns Downstream
Port Containment (DPC), its expected to use the "Error Disconnect
Recover" (EDR) notification to alert OSPM of a DPC event and if OS
supports EDR, its expected to handle the software state invalidation and
port recovery in OS, and also let firmware know the recovery status via
_OST ACPI call. Related _OST status codes can be found in ACPI
specification r6.3, sec 6.3.5.2.

Also, as per PCI firmware specification r3.2 Downstream Port Containment
Related Enhancements ECN, sec 4.5.1, table 4-6, If DPC is controlled by
firmware (firmware first mode), firmware is responsible for
configuring the DPC and OS is responsible for error recovery. Also, OS
is allowed to modify DPC registers only during the EDR notification
window.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---
drivers/pci/pci-acpi.c | 3 +
drivers/pci/pcie/Kconfig | 10 ++
drivers/pci/pcie/Makefile | 1 +
drivers/pci/pcie/edr.c | 249 ++++++++++++++++++++++++++++++++++++++
include/linux/pci-acpi.h | 8 ++
5 files changed, 271 insertions(+)
create mode 100644 drivers/pci/pcie/edr.c

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 0c02d500158f..6af5d6a04990 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -1258,6 +1258,7 @@ static void pci_acpi_setup(struct device *dev)

acpi_pci_wakeup(pci_dev, false);
acpi_device_power_add_dependent(adev, dev);
+ pci_acpi_add_edr_notifier(pci_dev);
}

static void pci_acpi_cleanup(struct device *dev)
@@ -1276,6 +1277,8 @@ static void pci_acpi_cleanup(struct device *dev)

device_set_wakeup_capable(dev, false);
}
+
+ pci_acpi_remove_edr_notifier(pci_dev);
}

static bool pci_acpi_bus_match(struct device *dev)
diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig
index 6e3c04b46fb1..772b1f4cb19e 100644
--- a/drivers/pci/pcie/Kconfig
+++ b/drivers/pci/pcie/Kconfig
@@ -140,3 +140,13 @@ config PCIE_BW
This enables PCI Express Bandwidth Change Notification. If
you know link width or rate changes occur only to correct
unreliable links, you may answer Y.
+
+config PCIE_EDR
+ bool "PCI Express Error Disconnect Recover support"
+ depends on PCIE_DPC && ACPI
+ help
+ This option adds Error Disconnect Recover support as specified
+ in the Downstream Port Containment Related Enhancements ECN to
+ the PCI Firmware Specification r3.2. Enable this if you want to
+ support hybrid DPC model which uses both firmware and OS to
+ implement DPC.
diff --git a/drivers/pci/pcie/Makefile b/drivers/pci/pcie/Makefile
index efb9d2e71e9e..68da9280ff11 100644
--- a/drivers/pci/pcie/Makefile
+++ b/drivers/pci/pcie/Makefile
@@ -13,3 +13,4 @@ obj-$(CONFIG_PCIE_PME) += pme.o
obj-$(CONFIG_PCIE_DPC) += dpc.o
obj-$(CONFIG_PCIE_PTM) += ptm.o
obj-$(CONFIG_PCIE_BW) += bw_notification.o
+obj-$(CONFIG_PCIE_EDR) += edr.o
diff --git a/drivers/pci/pcie/edr.c b/drivers/pci/pcie/edr.c
new file mode 100644
index 000000000000..2d8680be0302
--- /dev/null
+++ b/drivers/pci/pcie/edr.c
@@ -0,0 +1,249 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PCI DPC Error Disconnect Recover support driver
+ * Author: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
+ *
+ * Copyright (C) 2020 Intel Corp.
+ */
+
+#define dev_fmt(fmt) "EDR: " fmt
+
+#include <linux/pci.h>
+#include <linux/pci-acpi.h>
+
+#include "portdrv.h"
+#include "../pci.h"
+
+#define EDR_PORT_ENABLE_DSM 0x0C
+#define EDR_PORT_LOCATE_DSM 0x0D
+#define EDR_OST_SUCCESS 0x80
+#define EDR_OST_FAILED 0x81
+
+/*
+ * _DSM wrapper function to enable/disable DPC port.
+ * @pdev : PCI device structure.
+ *
+ * returns 0 on success or errno on failure.
+ */
+static int acpi_enable_dpc_port(struct pci_dev *pdev)
+{
+ struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
+ union acpi_object *obj, argv4, req;
+ int status = 0;
+
+ req.type = ACPI_TYPE_INTEGER;
+ req.integer.value = 1;
+
+ argv4.type = ACPI_TYPE_PACKAGE;
+ argv4.package.count = 1;
+ argv4.package.elements = &req;
+
+ /*
+ * Per the Downstream Port Containment Related Enhancements ECN to
+ * the PCI Firmware Specification r3.2, sec 4.6.12,
+ * EDR_PORT_ENABLE_DSM is optional. Return success if it's not
+ * implemented.
+ */
+ obj = acpi_evaluate_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
+ EDR_PORT_ENABLE_DSM, &argv4);
+ if (!obj)
+ return 0;
+
+ if (obj->type != ACPI_TYPE_INTEGER) {
+ pci_err(pdev, "_DSM 0x0C returns non integer value\n");
+ status = -EIO;
+ }
+
+ if (obj->integer.value != 1) {
+ pci_err(pdev, "failed to enable DPC port\n");
+ status = -EIO;
+ }
+
+ ACPI_FREE(obj);
+
+ return status;
+}
+
+/*
+ * _DSM wrapper function to locate DPC port.
+ * @pdev : Device which received EDR event.
+ *
+ * returns pci_dev or NULL.
+ */
+static struct pci_dev *acpi_dpc_port_get(struct pci_dev *pdev)
+{
+ struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
+ union acpi_object *obj;
+ u16 port;
+
+ obj = acpi_evaluate_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
+ EDR_PORT_LOCATE_DSM, NULL);
+ if (!obj)
+ return pci_dev_get(pdev);
+
+ if (obj->type != ACPI_TYPE_INTEGER) {
+ ACPI_FREE(obj);
+ pci_err(pdev, "_DSM 0x0D returns non integer value\n");
+ return NULL;
+ }
+
+ /*
+ * Firmware returns DPC port BDF details in following format:
+ * 15:8 = bus
+ * 7:3 = device
+ * 2:0 = function
+ */
+ port = obj->integer.value;
+
+ ACPI_FREE(obj);
+
+ return pci_get_domain_bus_and_slot(pci_domain_nr(pdev->bus),
+ PCI_BUS_NUM(port), port & 0xff);
+}
+
+/*
+ * _OST wrapper function to let firmware know the status of EDR event.
+ * @pdev : Device used to send _OST.
+ * @edev : Device which experienced EDR event.
+ * @status: Status of EDR event.
+ */
+static int acpi_send_edr_status(struct pci_dev *pdev, struct pci_dev *edev,
+ u16 status)
+{
+ struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
+ u32 ost_status;
+
+ pci_dbg(pdev, "Sending EDR status :%#x\n", status);
+
+ ost_status = PCI_DEVID(edev->bus->number, edev->devfn);
+ ost_status = (ost_status << 16) | status;
+
+ status = acpi_evaluate_ost(adev->handle,
+ ACPI_NOTIFY_DISCONNECT_RECOVER,
+ ost_status, NULL);
+ if (ACPI_FAILURE(status))
+ return -EINVAL;
+
+ return 0;
+}
+
+static void edr_handle_event(acpi_handle handle, u32 event, void *data)
+{
+ struct pci_dev *pdev = data, *edev;
+ pci_ers_result_t estate = PCI_ERS_RESULT_DISCONNECT;
+ u16 status;
+
+ pci_info(pdev, "ACPI event %#x received\n", event);
+
+ if (event != ACPI_NOTIFY_DISCONNECT_RECOVER)
+ return;
+
+ /*
+ * Check if _DSM(0xD) is available, and if present locate the
+ * port which issued EDR event.
+ */
+ edev = acpi_dpc_port_get(pdev);
+ if (!edev) {
+ pci_err(pdev, "Firmware failed to locate DPC port\n");
+ return;
+ }
+
+ pci_dbg(pdev, "Reported EDR dev: %s\n", pci_name(edev));
+
+ /*
+ * If port does not support DPC, just send the OST:
+ */
+ if (!edev->dpc_cap) {
+ pci_err(edev, "Firmware BUG, located port doesn't support DPC\n");
+ goto send_ost;
+ }
+
+ /* Check if there is a valid DPC trigger */
+ pci_read_config_word(edev, edev->dpc_cap + PCI_EXP_DPC_STATUS, &status);
+ if (!(status & PCI_EXP_DPC_STATUS_TRIGGER)) {
+ pci_err(edev, "Invalid DPC trigger %#010x\n", status);
+ goto send_ost;
+ }
+
+ dpc_process_error(edev);
+
+ /* Clear AER registers */
+ pci_aer_raw_clear_status(edev);
+
+ /*
+ * Irrespective of whether the DPC event is triggered by
+ * ERR_FATAL or ERR_NONFATAL, since the link is already down,
+ * use the FATAL error recovery path for both cases.
+ */
+ estate = pcie_do_recovery(edev, pci_channel_io_frozen, dpc_reset_link);
+
+ pci_dbg(edev, "DPC port successfully recovered\n");
+send_ost:
+
+ /*
+ * If recovery is successful, send _OST(0xF, BDF << 16 | 0x80)
+ * to firmware. If not successful, send _OST(0xF, BDF << 16 | 0x81).
+ */
+ if (estate == PCI_ERS_RESULT_RECOVERED)
+ acpi_send_edr_status(pdev, edev, EDR_OST_SUCCESS);
+ else
+ acpi_send_edr_status(pdev, edev, EDR_OST_FAILED);
+
+ pci_dev_put(edev);
+}
+
+void pci_acpi_add_edr_notifier(struct pci_dev *pdev)
+{
+ struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
+ acpi_status astatus;
+
+ if (!adev) {
+ pci_dbg(pdev, "No valid ACPI node, so skip EDR init\n");
+ return;
+ }
+
+ /*
+ * Per the Downstream Port Containment Related Enhancements ECN to
+ * the PCI Firmware Spec, r3.2, sec 4.5.1, table 4-6, EDR support
+ * can only be enabled if DPC is controlled by firmware.
+ *
+ * TODO: Remove dependency on ACPI FIRMWARE_FIRST bit to
+ * determine ownership of DPC between firmware or OS.
+ * Per the Downstream Port Containment Related Enhancements
+ * ECN to the PCI Firmware Spec, r3.2, sec 4.5.1, table 4-5,
+ * OS can use bit 7 of _OSC control field to negotiate control
+ * over DPC Capability.
+ */
+ if (!pcie_aer_get_firmware_first(pdev) || pcie_ports_dpc_native) {
+ pci_dbg(pdev, "OS handles AER/DPC, so skip EDR init\n");
+ return;
+ }
+
+ astatus = acpi_install_notify_handler(adev->handle, ACPI_SYSTEM_NOTIFY,
+ edr_handle_event, pdev);
+ if (ACPI_FAILURE(astatus)) {
+ pci_err(pdev, "Install ACPI_SYSTEM_NOTIFY handler failed\n");
+ return;
+ }
+
+ if (acpi_enable_dpc_port(pdev))
+ acpi_remove_notify_handler(adev->handle, ACPI_SYSTEM_NOTIFY,
+ edr_handle_event);
+
+ pci_dbg(pdev, "EDR notifier is added successfully\n");
+
+ return;
+}
+
+void pci_acpi_remove_edr_notifier(struct pci_dev *pdev)
+{
+ struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
+
+ if (!adev)
+ return;
+
+ pci_dbg(pdev, "EDR notifier is removed successfully\n");
+
+ acpi_remove_notify_handler(adev->handle, ACPI_SYSTEM_NOTIFY,
+ edr_handle_event);
+}
diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
index 62b7fdcc661c..2d155bfb8fbf 100644
--- a/include/linux/pci-acpi.h
+++ b/include/linux/pci-acpi.h
@@ -112,6 +112,14 @@ extern const guid_t pci_acpi_dsm_guid;
#define RESET_DELAY_DSM 0x08
#define FUNCTION_DELAY_DSM 0x09

+#ifdef CONFIG_PCIE_EDR
+void pci_acpi_add_edr_notifier(struct pci_dev *pdev);
+void pci_acpi_remove_edr_notifier(struct pci_dev *pdev);
+#else
+static inline void pci_acpi_add_edr_notifier(struct pci_dev *pdev) { }
+static inline void pci_acpi_remove_edr_notifier(struct pci_dev *pdev) { }
+#endif /* CONFIG_PCIE_EDR */
+
#else /* CONFIG_ACPI */
static inline void acpi_pci_add_bus(struct pci_bus *bus) { }
static inline void acpi_pci_remove_bus(struct pci_bus *bus) { }
--
2.21.0