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Subject[PATCH v3 4/5] PCI/DPC: Add Error Disconnect Recover (EDR) support
Date
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

As per PCI firmware specification v3.2 ECN
(https://members.pcisig.com/wg/PCI-SIG/document/12614), 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 let firmware know the recovery status via _OST
ACPI call.

Since EDR is a hybrid service, DPC service shall be enabled in OS even
if AER is not natively enabled in OS.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---
drivers/pci/pcie/Kconfig | 10 ++
drivers/pci/pcie/dpc.c | 206 ++++++++++++++++++++++++++++++++
drivers/pci/pcie/portdrv_core.c | 9 +-
3 files changed, 223 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig
index 362eb8cfa53b..9a05015af7cd 100644
--- a/drivers/pci/pcie/Kconfig
+++ b/drivers/pci/pcie/Kconfig
@@ -150,3 +150,13 @@ 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"
+ default n
+ depends on PCIE_DPC && ACPI
+ help
+ This options adds Error Disconnect Recover support as specified
+ in PCI firmware specification v3.2 Downstream Port Containment
+ Related Enhancements ECN. 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/dpc.c b/drivers/pci/pcie/dpc.c
index 95810b4b0adc..131fadd29ae2 100644
--- a/drivers/pci/pcie/dpc.c
+++ b/drivers/pci/pcie/dpc.c
@@ -11,6 +11,7 @@
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/pci.h>
+#include <linux/acpi.h>

#include "portdrv.h"
#include "../pci.h"
@@ -22,8 +23,22 @@ struct dpc_dev {
u8 rp_log_size;
/* Set True if DPC is handled in firmware */
bool firmware_dpc;
+ pci_ers_result_t error_state;
+#ifdef CONFIG_ACPI
+ struct acpi_device *adev;
+#endif
};

+#ifdef CONFIG_ACPI
+
+#define EDR_PORT_ENABLE_DSM 0x0C
+#define EDR_PORT_LOCATE_DSM 0x0D
+
+static const guid_t pci_acpi_dsm_guid =
+ GUID_INIT(0xe5c937d0, 0x3553, 0x4d7a,
+ 0x91, 0x17, 0xea, 0x4d, 0x19, 0xc3, 0x43, 0x4d);
+#endif
+
static const char * const rp_pio_error_string[] = {
"Configuration Request received UR Completion", /* Bit Position 0 */
"Configuration Request received CA Completion", /* Bit Position 1 */
@@ -297,6 +312,167 @@ static irqreturn_t dpc_irq(int irq, void *context)
return IRQ_HANDLED;
}

+static void dpc_error_resume(struct pci_dev *dev)
+{
+ struct dpc_dev *dpc = to_dpc_dev(dev);
+
+ dpc->error_state = PCI_ERS_RESULT_RECOVERED;
+}
+
+#ifdef CONFIG_ACPI
+
+/*
+ * _DSM wrapper function to enable/disable DPC port.
+ * @dpc : DPC device structure
+ * @enable: status of DPC port (0 or 1).
+ *
+ * returns 0 on success or errno on failure.
+ */
+static int acpi_enable_dpc_port(struct dpc_dev *dpc, bool enable)
+{
+ union acpi_object *obj;
+ int status;
+ union acpi_object argv4;
+ struct pci_dev *pdev = dpc->dev->port;
+
+ dev_dbg(&pdev->dev, "Enable DPC port, value:%d\n", enable);
+
+ argv4.type = ACPI_TYPE_INTEGER;
+ argv4.integer.value = enable;
+
+ obj = acpi_evaluate_dsm(dpc->adev->handle, &pci_acpi_dsm_guid, 1,
+ EDR_PORT_ENABLE_DSM, &argv4);
+ if (!obj)
+ return -EIO;
+
+ if (obj->type == ACPI_TYPE_INTEGER && obj->integer.value == enable)
+ status = 0;
+ else
+ status = -EIO;
+
+ ACPI_FREE(obj);
+
+ return status;
+}
+
+/*
+ * _DSM wrapper function to locate DPC port.
+ * @dpc : DPC device structure
+ *
+ * returns pci_dev.
+ */
+static struct pci_dev *acpi_locate_dpc_port(struct dpc_dev *dpc)
+{
+ union acpi_object *obj;
+ u16 port;
+ struct pci_dev *pdev = dpc->dev->port;
+
+ dev_dbg(&pdev->dev, "Locate DPC port\n");
+
+ obj = acpi_evaluate_dsm(dpc->adev->handle, &pci_acpi_dsm_guid, 1,
+ EDR_PORT_LOCATE_DSM, NULL);
+ if (!obj)
+ return dpc->dev->port;
+
+ if (obj->type == ACPI_TYPE_INTEGER) {
+ /*
+ * 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);
+ } else {
+ ACPI_FREE(obj);
+ return dpc->dev->port;
+ }
+
+ return pci_get_domain_bus_and_slot(0, PCI_BUS_NUM(port), port & 0xff);
+}
+
+/*
+ * _OST wrapper function to let firmware know the status of EDR event.
+ * @dpc : DPC device structure.
+ * @status: Status of EDR event.
+ */
+static int acpi_send_edr_status(struct dpc_dev *dpc, u16 status)
+{
+ u32 ost_status;
+ struct pci_dev *pdev = dpc->dev->port;
+
+ dev_dbg(&pdev->dev, "Sending EDR status :%x\n", status);
+
+ ost_status = PCI_DEVID(pdev->bus->number, pdev->devfn);
+ ost_status = (ost_status << 16) | status;
+
+ status = acpi_evaluate_ost(dpc->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 dpc_dev *dpc = (struct dpc_dev *) data;
+ struct pci_dev *pdev = dpc->dev->port;
+ u16 status, cap;
+
+ dev_info(&pdev->dev, "ACPI event %x received\n", event);
+
+ if (event != ACPI_NOTIFY_DISCONNECT_RECOVER)
+ return;
+
+ dev_info(&pdev->dev, "Valid EDR event received\n");
+
+ /*
+ * Check if _DSM(0xD) is available, and if present locate the
+ * port which issued EDR event.
+ */
+ pdev = acpi_locate_dpc_port(dpc);
+ if (!pdev) {
+ pdev = dpc->dev->port;
+ dev_err(&pdev->dev, "No valid port found\n");
+ return;
+ }
+
+ dpc = to_dpc_dev(pdev);
+ dpc->error_state = PCI_ERS_RESULT_DISCONNECT;
+ cap = dpc->cap_pos;
+
+ /*
+ * Check if the port supports DPC:
+ *
+ * If port supports DPC, then fall back to default error
+ * recovery.
+ */
+ if (cap) {
+ /* Check if there is a valid DPC trigger */
+ pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &status);
+ if (!(status & PCI_EXP_DPC_STATUS_TRIGGER)) {
+ dev_err(&pdev->dev, "Invalid DPC trigger %x\n", status);
+ return;
+ }
+ dpc_process_error(dpc);
+ }
+
+ /*
+ * If recovery is successful, send _OST(0xF, BDF << 16 | 0x80)
+ * to firmware. If not successful, send _OST(0xF, BDF << 16 | 0x81).
+ */
+ if (dpc->error_state == PCI_ERS_RESULT_RECOVERED)
+ status = 0x80;
+ else
+ status = 0x81;
+
+ acpi_send_edr_status(dpc, status);
+}
+
+#endif
+
#define FLAG(x, y) (((x) & (y)) ? '+' : '-')
static int dpc_probe(struct pcie_device *dev)
{
@@ -305,6 +481,10 @@ static int dpc_probe(struct pcie_device *dev)
struct device *device = &dev->device;
int status;
u16 ctl, cap;
+#ifdef CONFIG_ACPI
+ struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
+ acpi_status astatus;
+#endif

dpc = devm_kzalloc(device, sizeof(*dpc), GFP_KERNEL);
if (!dpc)
@@ -313,6 +493,7 @@ static int dpc_probe(struct pcie_device *dev)
dpc->cap_pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_DPC);
dpc->dev = dev;
set_service_data(dev, dpc);
+ dpc->error_state = PCI_ERS_RESULT_NONE;

if (pcie_aer_get_firmware_first(pdev))
dpc->firmware_dpc = 1;
@@ -335,6 +516,30 @@ static int dpc_probe(struct pcie_device *dev)
}
}

+#ifdef CONFIG_ACPI
+ if (dpc->firmware_dpc) {
+ if (!adev) {
+ dev_err(device, "No valid ACPI device found\n");
+ return -ENODEV;
+ }
+
+ dpc->adev = adev;
+
+ /* Register notifier for ACPI_SYSTEM_NOTIFY events */
+ astatus = acpi_install_notify_handler(adev->handle,
+ ACPI_SYSTEM_NOTIFY,
+ edr_handle_event,
+ dpc);
+
+ if (ACPI_FAILURE(astatus)) {
+ dev_err(device,
+ "Install ACPI_SYSTEM_NOTIFY handler failed\n");
+ return -EBUSY;
+ }
+
+ acpi_enable_dpc_port(dpc, true);
+ }
+#endif
pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CAP, &cap);
pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl);

@@ -385,6 +590,7 @@ static struct pcie_port_service_driver dpcdriver = {
.probe = dpc_probe,
.remove = dpc_remove,
.reset_link = dpc_reset_link,
+ .error_resume = dpc_error_resume,
};

int __init pcie_dpc_init(void)
diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
index 0a59ac574be1..1b54a39df795 100644
--- a/drivers/pci/pcie/portdrv_core.c
+++ b/drivers/pci/pcie/portdrv_core.c
@@ -250,9 +250,14 @@ static int get_port_device_capability(struct pci_dev *dev)
pcie_pme_interrupt_enable(dev, false);
}

+ /*
+ * If EDR support is enabled in OS, then even if AER is not handled in
+ * OS, DPC service can be enabled.
+ */
if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) &&
- pci_aer_available() && services & PCIE_PORT_SERVICE_AER &&
- (pcie_ports_native || host->native_dpc))
+ ((IS_ENABLED(CONFIG_PCIE_EDR) && !host->native_dpc) ||
+ (pci_aer_available() && services & PCIE_PORT_SERVICE_AER &&
+ (pcie_ports_native || host->native_dpc))))
services |= PCIE_PORT_SERVICE_DPC;

if (pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM ||
--
2.20.1
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