Add Error Disconnect Recover (EDR) support

From: Kuppuswamy Sathyanarayanan <[email protected]>

As per PCI Firmware Specification, r3.2 ECN
(https://members.pcisig.com/wg/PCI-SIG/document/12614), OS can use bit 7 of _OSC Control Field to negotiate control over Downstream Port Containment (DPC) configuration of PCIe port.

From: Kuppuswamy Sathyanarayanan <[email protected]>

Error Disconnect Recover (EDR) support allows OS to handle the error recovery even when DPC configuration is handled by firmware. So allow dpc_probe() to continue even if firmware first mode is enabed. This is a prepratory patch for adding EDR support.

Signed-off-by Kuppuswamy Sathyanarayanan <[email protected]>

---
 drivers/pci/pcie/dpc.c | 49 +++++++++++++++++++++++++++++++-----------
 1 file changed, 36 insertions(+), 13 deletions(-)

drivers/pci/pcie/dpc.c +36 -13

index 7b77754a82de..0c9ce876e450 100644
@@ -20,6 +20,8 @@ struct dpc_dev {
 	u16			cap_pos;
 	bool			rp_extensions;
 	u8			rp_log_size;
+	/* Set True if DPC is handled in firmware */
+	bool			firmware_dpc;
 };
 
 static const char * const rp_pio_error_string[] = {

@@ -67,6 +69,9 @@ void pci_save_dpc_state(struct pci_dev *dev)
 	if (!dpc)
 		return;
 
+	if (dpc->firmware_dpc)
+		return;
+
 	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_DPC);
 	if (!save_state)
 		return;

@@ -88,6 +93,9 @@ void pci_restore_dpc_state(struct pci_dev *dev)
 	if (!dpc)
 		return;
 
+	if (dpc->firmware_dpc)
+		return;
+
 	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_DPC);
 	if (!save_state)
 		return;

@@ -292,9 +300,6 @@ static int dpc_probe(struct pcie_device *dev)
 	int status;
 	u16 ctl, cap;
 
-	if (pcie_aer_get_firmware_first(pdev))
-		return -ENOTSUPP;
-
 	dpc = devm_kzalloc(device, sizeof(*dpc), GFP_KERNEL);
 	if (!dpc)
 		return -ENOMEM;

@@ -303,13 +308,25 @@ static int dpc_probe(struct pcie_device *dev)
 	dpc->dev = dev;
 	set_service_data(dev, dpc);
 
-	status = devm_request_threaded_irq(device, dev->irq, dpc_irq,
-					   dpc_handler, IRQF_SHARED,
-					   "pcie-dpc", dpc);
-	if (status) {
-		dev_warn(device, "request IRQ%d failed: %d\n", dev->irq,
-			 status);
-		return status;
+	if (pcie_aer_get_firmware_first(pdev))
+		dpc->firmware_dpc = 1;
+
+	/*
+	 * If DPC is handled in firmware and ACPI support is not enabled in OS,
+	 * then its not useful to proceed with probe. So, return error.
+	 */
+	if (dpc->firmware_dpc && !IS_ENABLED(CONFIG_ACPI))
+		return -ENODEV;
+
+	if (!dpc->firmware_dpc) {
+		status = devm_request_threaded_irq(device, dev->irq, dpc_irq,
+						   dpc_handler, IRQF_SHARED,
+						   "pcie-dpc", dpc);
+		if (status) {
+			dev_warn(device, "request IRQ%d failed: %d\n", dev->irq,
+				 status);
+			return status;
+		}
 	}
 
 	pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CAP, &cap);

@@ -324,9 +341,12 @@ static int dpc_probe(struct pcie_device *dev)
 			dpc->rp_log_size = 0;
 		}
 	}
-
-	ctl = (ctl & 0xfff4) | PCI_EXP_DPC_CTL_EN_FATAL | PCI_EXP_DPC_CTL_INT_EN;
-	pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, ctl);
+	if (!dpc->firmware_dpc) {
+		ctl = (ctl & 0xfff4) |
+			(PCI_EXP_DPC_CTL_EN_FATAL | PCI_EXP_DPC_CTL_INT_EN);
+		pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL,
+				      ctl);
+	}
 
 	dev_info(device, "DPC error containment capabilities: Int Msg #%d, RPExt%c PoisonedTLP%c SwTrigger%c RP PIO Log %d, DL_ActiveErr%c\n",
 		cap & PCI_EXP_DPC_IRQ, FLAG(cap, PCI_EXP_DPC_CAP_RP_EXT),

@@ -344,6 +364,9 @@ static void dpc_remove(struct pcie_device *dev)
 	struct pci_dev *pdev = dev->port;
 	u16 ctl;
 
+	if (dpc->firmware_dpc)
+		return;
+
 	pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl);
 	ctl &= ~(PCI_EXP_DPC_CTL_EN_FATAL | PCI_EXP_DPC_CTL_INT_EN);
 	pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, ctl);

Signature · 1 line

2.20.1

From: Kuppuswamy Sathyanarayanan <[email protected]>

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 <[email protected]>

---
 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(-)

drivers/pci/pcie/Kconfig +10 -0

index 362eb8cfa53b..9a05015af7cd 100644
@@ -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.

drivers/pci/pcie/dpc.c +5 -0

index 95810b4b0adc..131fadd29ae2 100644
@@ -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

drivers/pci/pcie/dpc.c +7 -0

+#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;

drivers/pci/pcie/dpc.c +21 -0

+	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

drivers/pci/pcie/dpc.c +7 -0

+	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) {
+		/*

drivers/pci/pcie/dpc.c +28 -0

+}
+
+/*
+ * _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)
+{

drivers/pci/pcie/dpc.c +6 -0

+	dpc->error_state = PCI_ERS_RESULT_DISCONNECT;
+	cap = dpc->cap_pos;
+
+	/*
+	 * Check if the port supports DPC:
+	 *

drivers/pci/pcie/dpc.c +17 -0

+		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)
 {

drivers/pci/pcie/dpc.c +1 -0

 	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;

drivers/pci/pcie/dpc.c +15 -0

+		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)

drivers/pci/pcie/portdrv_core.c +7 -2

index 0a59ac574be1..1b54a39df795 100644
@@ -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 ||

Signature · 1 line

2.20.1

From: Kuppuswamy Sathyanarayanan <[email protected]>

This patchset adds support for following features:

1. Error Disconnect Recover (EDR) support.
2. _OSC based negotiation support for DPC.

You can find EDR spec in the following link.

https://members.pcisig.com/wg/PCI-SIG/document/12614

Changes since v1:
* Rebased on top of v5.1-rc1