Date:	Mon, 11 Mar 2013 19:55:40 +0000
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	David Miller <davem@...emloft.net>
CC:	<netdev@...r.kernel.org>, <linux-net-drivers@...arflare.com>,
	<scrum-linux@...arflare.com>
Subject: [PATCH net-next 11/22] sfc: Add AER and EEH support for Siena

From:  Alexandre Rames <arames@...arflare.com>

The Linux side of EEH is triggered by MMIO reads, but this
driver's data path does not issue any MMIO reads (except in
legacy interrupt mode).  Therefore add a monitor function
to poll EEH periodically.

When preparing to reset the device based on our own error
detection, also poll EEH and defer to its recovery mechanism
if appropriate.

[bwh: Use a separate condition for the initial link poll; fix some
 style errors]
Signed-off-by: Ben Hutchings <bhutchings@...arflare.com>
---
 drivers/net/ethernet/sfc/efx.c        |  207 +++++++++++++++++++++++++++++----
 drivers/net/ethernet/sfc/enum.h       |   12 ++-
 drivers/net/ethernet/sfc/net_driver.h |    1 +
 drivers/net/ethernet/sfc/siena.c      |   22 ++++-
 4 files changed, 216 insertions(+), 26 deletions(-)

diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index 11a8108..5e1ddc5 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -21,7 +21,9 @@
 #include <linux/ethtool.h>
 #include <linux/topology.h>
 #include <linux/gfp.h>
+#include <linux/pci.h>
 #include <linux/cpu_rmap.h>
+#include <linux/aer.h>
 #include "net_driver.h"
 #include "efx.h"
 #include "nic.h"
@@ -71,17 +73,19 @@ const char *const efx_loopback_mode_names[] = {
 
 const unsigned int efx_reset_type_max = RESET_TYPE_MAX;
 const char *const efx_reset_type_names[] = {
-	[RESET_TYPE_INVISIBLE]     = "INVISIBLE",
-	[RESET_TYPE_ALL]           = "ALL",
-	[RESET_TYPE_WORLD]         = "WORLD",
-	[RESET_TYPE_DISABLE]       = "DISABLE",
-	[RESET_TYPE_TX_WATCHDOG]   = "TX_WATCHDOG",
-	[RESET_TYPE_INT_ERROR]     = "INT_ERROR",
-	[RESET_TYPE_RX_RECOVERY]   = "RX_RECOVERY",
-	[RESET_TYPE_RX_DESC_FETCH] = "RX_DESC_FETCH",
-	[RESET_TYPE_TX_DESC_FETCH] = "TX_DESC_FETCH",
-	[RESET_TYPE_TX_SKIP]       = "TX_SKIP",
-	[RESET_TYPE_MC_FAILURE]    = "MC_FAILURE",
+	[RESET_TYPE_INVISIBLE]          = "INVISIBLE",
+	[RESET_TYPE_ALL]                = "ALL",
+	[RESET_TYPE_RECOVER_OR_ALL]     = "RECOVER_OR_ALL",
+	[RESET_TYPE_WORLD]              = "WORLD",
+	[RESET_TYPE_RECOVER_OR_DISABLE] = "RECOVER_OR_DISABLE",
+	[RESET_TYPE_DISABLE]            = "DISABLE",
+	[RESET_TYPE_TX_WATCHDOG]        = "TX_WATCHDOG",
+	[RESET_TYPE_INT_ERROR]          = "INT_ERROR",
+	[RESET_TYPE_RX_RECOVERY]        = "RX_RECOVERY",
+	[RESET_TYPE_RX_DESC_FETCH]      = "RX_DESC_FETCH",
+	[RESET_TYPE_TX_DESC_FETCH]      = "TX_DESC_FETCH",
+	[RESET_TYPE_TX_SKIP]            = "TX_SKIP",
+	[RESET_TYPE_MC_FAILURE]         = "MC_FAILURE",
 };
 
 #define EFX_MAX_MTU (9 * 1024)
@@ -117,9 +121,12 @@ MODULE_PARM_DESC(separate_tx_channels,
 static int napi_weight = 64;
 
 /* This is the time (in jiffies) between invocations of the hardware
- * monitor.  On Falcon-based NICs, this will:
+ * monitor.
+ * On Falcon-based NICs, this will:
  * - Check the on-board hardware monitor;
  * - Poll the link state and reconfigure the hardware as necessary.
+ * On Siena-based NICs for power systems with EEH support, this will give EEH a
+ * chance to start.
  */
 static unsigned int efx_monitor_interval = 1 * HZ;
 
@@ -203,13 +210,14 @@ static void efx_stop_all(struct efx_nic *efx);
 #define EFX_ASSERT_RESET_SERIALISED(efx)		\
 	do {						\
 		if ((efx->state == STATE_READY) ||	\
+		    (efx->state == STATE_RECOVERY) ||	\
 		    (efx->state == STATE_DISABLED))	\
 			ASSERT_RTNL();			\
 	} while (0)
 
 static int efx_check_disabled(struct efx_nic *efx)
 {
-	if (efx->state == STATE_DISABLED) {
+	if (efx->state == STATE_DISABLED || efx->state == STATE_RECOVERY) {
 		netif_err(efx, drv, efx->net_dev,
 			  "device is disabled due to earlier errors\n");
 		return -EIO;
@@ -677,7 +685,7 @@ static void efx_stop_datapath(struct efx_nic *efx)
 	BUG_ON(efx->port_enabled);
 
 	/* Only perform flush if dma is enabled */
-	if (dev->is_busmaster) {
+	if (dev->is_busmaster && efx->state != STATE_RECOVERY) {
 		rc = efx_nic_flush_queues(efx);
 
 		if (rc && EFX_WORKAROUND_7803(efx)) {
@@ -1590,13 +1598,15 @@ static void efx_start_all(struct efx_nic *efx)
 	efx_start_port(efx);
 	efx_start_datapath(efx);
 
-	/* Start the hardware monitor if there is one. Otherwise (we're link
-	 * event driven), we have to poll the PHY because after an event queue
-	 * flush, we could have a missed a link state change */
-	if (efx->type->monitor != NULL) {
+	/* Start the hardware monitor if there is one */
+	if (efx->type->monitor != NULL)
 		queue_delayed_work(efx->workqueue, &efx->monitor_work,
 				   efx_monitor_interval);
-	} else {
+
+	/* If link state detection is normally event-driven, we have
+	 * to poll now because we could have missed a change
+	 */
+	if (efx_nic_rev(efx) >= EFX_REV_SIENA_A0) {
 		mutex_lock(&efx->mac_lock);
 		if (efx->phy_op->poll(efx))
 			efx_link_status_changed(efx);
@@ -2303,7 +2313,9 @@ int efx_reset(struct efx_nic *efx, enum reset_type method)
 
 out:
 	/* Leave device stopped if necessary */
-	disabled = rc || method == RESET_TYPE_DISABLE;
+	disabled = rc ||
+		method == RESET_TYPE_DISABLE ||
+		method == RESET_TYPE_RECOVER_OR_DISABLE;
 	rc2 = efx_reset_up(efx, method, !disabled);
 	if (rc2) {
 		disabled = true;
@@ -2322,13 +2334,48 @@ out:
 	return rc;
 }
 
+/* Try recovery mechanisms.
+ * For now only EEH is supported.
+ * Returns 0 if the recovery mechanisms are unsuccessful.
+ * Returns a non-zero value otherwise.
+ */
+static int efx_try_recovery(struct efx_nic *efx)
+{
+#ifdef CONFIG_EEH
+	/* A PCI error can occur and not be seen by EEH because nothing
+	 * happens on the PCI bus. In this case the driver may fail and
+	 * schedule a 'recover or reset', leading to this recovery handler.
+	 * Manually call the eeh failure check function.
+	 */
+	struct eeh_dev *eehdev =
+		of_node_to_eeh_dev(pci_device_to_OF_node(efx->pci_dev));
+
+	if (eeh_dev_check_failure(eehdev)) {
+		/* The EEH mechanisms will handle the error and reset the
+		 * device if necessary.
+		 */
+		return 1;
+	}
+#endif
+	return 0;
+}
+
 /* The worker thread exists so that code that cannot sleep can
  * schedule a reset for later.
  */
 static void efx_reset_work(struct work_struct *data)
 {
 	struct efx_nic *efx = container_of(data, struct efx_nic, reset_work);
-	unsigned long pending = ACCESS_ONCE(efx->reset_pending);
+	unsigned long pending;
+	enum reset_type method;
+
+	pending = ACCESS_ONCE(efx->reset_pending);
+	method = fls(pending) - 1;
+
+	if ((method == RESET_TYPE_RECOVER_OR_DISABLE ||
+	     method == RESET_TYPE_RECOVER_OR_ALL) &&
+	    efx_try_recovery(efx))
+		return;
 
 	if (!pending)
 		return;
@@ -2340,7 +2387,7 @@ static void efx_reset_work(struct work_struct *data)
 	 * it cannot change again.
 	 */
 	if (efx->state == STATE_READY)
-		(void)efx_reset(efx, fls(pending) - 1);
+		(void)efx_reset(efx, method);
 
 	rtnl_unlock();
 }
@@ -2349,11 +2396,20 @@ void efx_schedule_reset(struct efx_nic *efx, enum reset_type type)
 {
 	enum reset_type method;
 
+	if (efx->state == STATE_RECOVERY) {
+		netif_dbg(efx, drv, efx->net_dev,
+			  "recovering: skip scheduling %s reset\n",
+			  RESET_TYPE(type));
+		return;
+	}
+
 	switch (type) {
 	case RESET_TYPE_INVISIBLE:
 	case RESET_TYPE_ALL:
+	case RESET_TYPE_RECOVER_OR_ALL:
 	case RESET_TYPE_WORLD:
 	case RESET_TYPE_DISABLE:
+	case RESET_TYPE_RECOVER_OR_DISABLE:
 		method = type;
 		netif_dbg(efx, drv, efx->net_dev, "scheduling %s reset\n",
 			  RESET_TYPE(method));
@@ -2563,6 +2619,8 @@ static void efx_pci_remove(struct pci_dev *pci_dev)
 	efx_fini_struct(efx);
 	pci_set_drvdata(pci_dev, NULL);
 	free_netdev(efx->net_dev);
+
+	pci_disable_pcie_error_reporting(pci_dev);
 };
 
 /* NIC VPD information
@@ -2735,6 +2793,11 @@ static int efx_pci_probe(struct pci_dev *pci_dev,
 		netif_warn(efx, probe, efx->net_dev,
 			   "failed to create MTDs (%d)\n", rc);
 
+	rc = pci_enable_pcie_error_reporting(pci_dev);
+	if (rc && rc != -EINVAL)
+		netif_warn(efx, probe, efx->net_dev,
+			   "pci_enable_pcie_error_reporting failed (%d)\n", rc);
+
 	return 0;
 
  fail4:
@@ -2859,12 +2922,112 @@ static const struct dev_pm_ops efx_pm_ops = {
 	.restore	= efx_pm_resume,
 };
 
+/* A PCI error affecting this device was detected.
+ * At this point MMIO and DMA may be disabled.
+ * Stop the software path and request a slot reset.
+ */
+pci_ers_result_t efx_io_error_detected(struct pci_dev *pdev,
+				       enum pci_channel_state state)
+{
+	pci_ers_result_t status = PCI_ERS_RESULT_RECOVERED;
+	struct efx_nic *efx = pci_get_drvdata(pdev);
+
+	if (state == pci_channel_io_perm_failure)
+		return PCI_ERS_RESULT_DISCONNECT;
+
+	rtnl_lock();
+
+	if (efx->state != STATE_DISABLED) {
+		efx->state = STATE_RECOVERY;
+		efx->reset_pending = 0;
+
+		efx_device_detach_sync(efx);
+
+		efx_stop_all(efx);
+		efx_stop_interrupts(efx, false);
+
+		status = PCI_ERS_RESULT_NEED_RESET;
+	} else {
+		/* If the interface is disabled we don't want to do anything
+		 * with it.
+		 */
+		status = PCI_ERS_RESULT_RECOVERED;
+	}
+
+	rtnl_unlock();
+
+	pci_disable_device(pdev);
+
+	return status;
+}
+
+/* Fake a successfull reset, which will be performed later in efx_io_resume. */
+pci_ers_result_t efx_io_slot_reset(struct pci_dev *pdev)
+{
+	struct efx_nic *efx = pci_get_drvdata(pdev);
+	pci_ers_result_t status = PCI_ERS_RESULT_RECOVERED;
+	int rc;
+
+	if (pci_enable_device(pdev)) {
+		netif_err(efx, hw, efx->net_dev,
+			  "Cannot re-enable PCI device after reset.\n");
+		status =  PCI_ERS_RESULT_DISCONNECT;
+	}
+
+	rc = pci_cleanup_aer_uncorrect_error_status(pdev);
+	if (rc) {
+		netif_err(efx, hw, efx->net_dev,
+		"pci_cleanup_aer_uncorrect_error_status failed (%d)\n", rc);
+		/* Non-fatal error. Continue. */
+	}
+
+	return status;
+}
+
+/* Perform the actual reset and resume I/O operations. */
+static void efx_io_resume(struct pci_dev *pdev)
+{
+	struct efx_nic *efx = pci_get_drvdata(pdev);
+	int rc;
+
+	rtnl_lock();
+
+	if (efx->state == STATE_DISABLED)
+		goto out;
+
+	rc = efx_reset(efx, RESET_TYPE_ALL);
+	if (rc) {
+		netif_err(efx, hw, efx->net_dev,
+			  "efx_reset failed after PCI error (%d)\n", rc);
+	} else {
+		efx->state = STATE_READY;
+		netif_dbg(efx, hw, efx->net_dev,
+			  "Done resetting and resuming IO after PCI error.\n");
+	}
+
+out:
+	rtnl_unlock();
+}
+
+/* For simplicity and reliability, we always require a slot reset and try to
+ * reset the hardware when a pci error affecting the device is detected.
+ * We leave both the link_reset and mmio_enabled callback unimplemented:
+ * with our request for slot reset the mmio_enabled callback will never be
+ * called, and the link_reset callback is not used by AER or EEH mechanisms.
+ */
+static struct pci_error_handlers efx_err_handlers = {
+	.error_detected = efx_io_error_detected,
+	.slot_reset	= efx_io_slot_reset,
+	.resume		= efx_io_resume,
+};
+
 static struct pci_driver efx_pci_driver = {
 	.name		= KBUILD_MODNAME,
 	.id_table	= efx_pci_table,
 	.probe		= efx_pci_probe,
 	.remove		= efx_pci_remove,
 	.driver.pm	= &efx_pm_ops,
+	.err_handler	= &efx_err_handlers,
 };
 
 /**************************************************************************
diff --git a/drivers/net/ethernet/sfc/enum.h b/drivers/net/ethernet/sfc/enum.h
index 182dbe2..ab8fb58 100644
--- a/drivers/net/ethernet/sfc/enum.h
+++ b/drivers/net/ethernet/sfc/enum.h
@@ -137,8 +137,12 @@ enum efx_loopback_mode {
  * Reset methods are numbered in order of increasing scope.
  *
  * @RESET_TYPE_INVISIBLE: Reset datapath and MAC (Falcon only)
+ * @RESET_TYPE_RECOVER_OR_ALL: Try to recover. Apply RESET_TYPE_ALL
+ * if unsuccessful.
  * @RESET_TYPE_ALL: Reset datapath, MAC and PHY
  * @RESET_TYPE_WORLD: Reset as much as possible
+ * @RESET_TYPE_RECOVER_OR_DISABLE: Try to recover. Apply RESET_TYPE_DISABLE if
+ * unsuccessful.
  * @RESET_TYPE_DISABLE: Reset datapath, MAC and PHY; leave NIC disabled
  * @RESET_TYPE_TX_WATCHDOG: reset due to TX watchdog
  * @RESET_TYPE_INT_ERROR: reset due to internal error
@@ -150,9 +154,11 @@ enum efx_loopback_mode {
  */
 enum reset_type {
 	RESET_TYPE_INVISIBLE = 0,
-	RESET_TYPE_ALL = 1,
-	RESET_TYPE_WORLD = 2,
-	RESET_TYPE_DISABLE = 3,
+	RESET_TYPE_RECOVER_OR_ALL = 1,
+	RESET_TYPE_ALL = 2,
+	RESET_TYPE_WORLD = 3,
+	RESET_TYPE_RECOVER_OR_DISABLE = 4,
+	RESET_TYPE_DISABLE = 5,
 	RESET_TYPE_MAX_METHOD,
 	RESET_TYPE_TX_WATCHDOG,
 	RESET_TYPE_INT_ERROR,
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index c83fe09..9e90081 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -429,6 +429,7 @@ enum nic_state {
 	STATE_UNINIT = 0,	/* device being probed/removed or is frozen */
 	STATE_READY = 1,	/* hardware ready and netdev registered */
 	STATE_DISABLED = 2,	/* device disabled due to hardware errors */
+	STATE_RECOVERY = 3,	/* device recovering from PCI error */
 };
 
 /*
diff --git a/drivers/net/ethernet/sfc/siena.c b/drivers/net/ethernet/sfc/siena.c
index ba40f67..e07ff0d 100644
--- a/drivers/net/ethernet/sfc/siena.c
+++ b/drivers/net/ethernet/sfc/siena.c
@@ -202,7 +202,7 @@ out:
 
 static enum reset_type siena_map_reset_reason(enum reset_type reason)
 {
-	return RESET_TYPE_ALL;
+	return RESET_TYPE_RECOVER_OR_ALL;
 }
 
 static int siena_map_reset_flags(u32 *flags)
@@ -245,6 +245,22 @@ static int siena_reset_hw(struct efx_nic *efx, enum reset_type method)
 		return efx_mcdi_reset_port(efx);
 }
 
+#ifdef CONFIG_EEH
+/* When a PCI device is isolated from the bus, a subsequent MMIO read is
+ * required for the kernel EEH mechanisms to notice. As the Solarflare driver
+ * was written to minimise MMIO read (for latency) then a periodic call to check
+ * the EEH status of the device is required so that device recovery can happen
+ * in a timely fashion.
+ */
+static void siena_monitor(struct efx_nic *efx)
+{
+	struct eeh_dev *eehdev =
+		of_node_to_eeh_dev(pci_device_to_OF_node(efx->pci_dev));
+
+	eeh_dev_check_failure(eehdev);
+}
+#endif
+
 static int siena_probe_nvconfig(struct efx_nic *efx)
 {
 	u32 caps = 0;
@@ -665,7 +681,11 @@ const struct efx_nic_type siena_a0_nic_type = {
 	.init = siena_init_nic,
 	.dimension_resources = siena_dimension_resources,
 	.fini = efx_port_dummy_op_void,
+#ifdef CONFIG_EEH
+	.monitor = siena_monitor,
+#else
 	.monitor = NULL,
+#endif
 	.map_reset_reason = siena_map_reset_reason,
 	.map_reset_flags = siena_map_reset_flags,
 	.reset = siena_reset_hw,
-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.




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