[PATCH] s2io: add PCI error recovery support

[linas@austin.ibm.com (Linas Vepstas)]

Koushik, Raju,

Please review, comment, and if you find this acceptable, 
please forward upstream. This patch incorporates all of 
fixes resulting from the last set of discussions, circa 
November 2006.

--linas

This patch adds PCI error recovery support to the 
s2io 10-Gigabit ethernet device driver. Fourth revision,
blocks interrupts and the watchdog. Adds a flag to 
s2io_down(), to avoid doing I/O when PCI bus is offline.

Tested, seems to work well.

Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Acked-by: Ramkrishna Vepa <Ramkrishna.Vepa@neterion.com>
Cc: Raghavendra Koushik <raghavendra.koushik@neterion.com>
Cc: Ananda Raju <Ananda.Raju@neterion.com>
Cc: Wen Xiong <wenxiong@us.ibm.com>

----
 drivers/net/s2io.c |  116 ++++++++++++++++++++++++++++++++++++++++++++++++++---
 drivers/net/s2io.h |    5 ++
 2 files changed, 116 insertions(+), 5 deletions(-)

Index: linux-2.6.20-git4/drivers/net/s2io.c
===================================================================
--- linux-2.6.20-git4.orig/drivers/net/s2io.c	2007-02-15 15:39:35.000000000 -0600
+++ linux-2.6.20-git4/drivers/net/s2io.c	2007-02-15 16:15:10.000000000 -0600
@@ -435,11 +435,18 @@ static struct pci_device_id s2io_tbl[] _
 
 MODULE_DEVICE_TABLE(pci, s2io_tbl);
 
+static struct pci_error_handlers s2io_err_handler = {
+	.error_detected = s2io_io_error_detected,
+	.slot_reset = s2io_io_slot_reset,
+	.resume = s2io_io_resume,
+};
+
 static struct pci_driver s2io_driver = {
       .name = "S2IO",
       .id_table = s2io_tbl,
       .probe = s2io_init_nic,
       .remove = __devexit_p(s2io_rem_nic),
+      .err_handler = &s2io_err_handler,
 };
 
 /* A simplifier macro used both by init and free shared_mem Fns(). */
@@ -2577,6 +2584,9 @@ static void s2io_netpoll(struct net_devi
 	u64 val64 = 0xFFFFFFFFFFFFFFFFULL;
 	int i;
 
+	if (pci_channel_offline(nic->pdev))
+		return;
+
 	disable_irq(dev->irq);
 
 	atomic_inc(&nic->isr_cnt);
@@ -3079,6 +3089,8 @@ static void alarm_intr_handler(struct s2
 	int i;
 	if (atomic_read(&nic->card_state) == CARD_DOWN)
 		return;
+	if (pci_channel_offline(nic->pdev))
+		return;
 	nic->mac_control.stats_info->sw_stat.ring_full_cnt = 0;
 	/* Handling the XPAK counters update */
 	if(nic->mac_control.stats_info->xpak_stat.xpak_timer_count < 72000) {
@@ -4117,6 +4129,10 @@ static irqreturn_t s2io_isr(int irq, voi
 	struct mac_info *mac_control;
 	struct config_param *config;
 
+	/* Pretend we handled any irq's from a disconnected card */
+	if (pci_channel_offline(sp->pdev))
+		return IRQ_NONE;
+
 	atomic_inc(&sp->isr_cnt);
 	mac_control = &sp->mac_control;
 	config = &sp->config;
@@ -6188,7 +6204,7 @@ static void s2io_rem_isr(struct s2io_nic
 	} while(cnt < 5);
 }
 
-static void s2io_card_down(struct s2io_nic * sp)
+static void do_s2io_card_down(struct s2io_nic * sp, int do_io)
 {
 	int cnt = 0;
 	struct XENA_dev_config __iomem *bar0 = sp->bar0;
@@ -6203,7 +6219,8 @@ static void s2io_card_down(struct s2io_n
 	atomic_set(&sp->card_state, CARD_DOWN);
 
 	/* disable Tx and Rx traffic on the NIC */
-	stop_nic(sp);
+	if (do_io)
+		stop_nic(sp);
 
 	s2io_rem_isr(sp);
 
@@ -6211,7 +6228,7 @@ static void s2io_card_down(struct s2io_n
 	tasklet_kill(&sp->task);
 
 	/* Check if the device is Quiescent and then Reset the NIC */
-	do {
+	while(do_io) {
 		/* As per the HW requirement we need to replenish the
 		 * receive buffer to avoid the ring bump. Since there is
 		 * no intention of processing the Rx frame at this pointwe are
@@ -6236,8 +6253,9 @@ static void s2io_card_down(struct s2io_n
 				  (unsigned long long) val64);
 			break;
 		}
-	} while (1);
-	s2io_reset(sp);
+	}
+	if (do_io)
+		s2io_reset(sp);
 
 	spin_lock_irqsave(&sp->tx_lock, flags);
 	/* Free all Tx buffers */
@@ -6252,6 +6270,11 @@ static void s2io_card_down(struct s2io_n
 	clear_bit(0, &(sp->link_state));
 }
 
+static void s2io_card_down(struct s2io_nic * sp)
+{
+	do_s2io_card_down(sp, 1);
+}
+
 static int s2io_card_up(struct s2io_nic * sp)
 {
 	int i, ret = 0;
@@ -7536,3 +7559,86 @@ static void lro_append_pkt(struct s2io_n
 	sp->mac_control.stats_info->sw_stat.clubbed_frms_cnt++;
 	return;
 }
+
+/**
+ * s2io_io_error_detected - called when PCI error is detected
+ * @pdev: Pointer to PCI device
+ * @state: The current pci conneection state
+ *
+ * This function is called after a PCI bus error affecting
+ * this device has been detected.
+ */
+static pci_ers_result_t s2io_io_error_detected(struct pci_dev *pdev,
+                                               pci_channel_state_t state)
+{
+	struct net_device *netdev = pci_get_drvdata(pdev);
+	struct s2io_nic *sp = netdev->priv;
+
+	netif_device_detach(netdev);
+
+	if (netif_running(netdev)) {
+		/* Bring down the card, while avoiding PCI I/O */
+		do_s2io_card_down(sp, 0);
+		sp->device_close_flag = TRUE;	/* Device is shut down. */
+	}
+	pci_disable_device(pdev);
+
+	return PCI_ERS_RESULT_NEED_RESET;
+}
+
+/**
+ * s2io_io_slot_reset - called after the pci bus has been reset.
+ * @pdev: Pointer to PCI device
+ *
+ * Restart the card from scratch, as if from a cold-boot.
+ * At this point, the card has exprienced a hard reset,
+ * followed by fixups by BIOS, and has its config space
+ * set up identically to what it was at cold boot.
+ */
+static pci_ers_result_t s2io_io_slot_reset(struct pci_dev *pdev)
+{
+	struct net_device *netdev = pci_get_drvdata(pdev);
+	struct s2io_nic *sp = netdev->priv;
+
+	if (pci_enable_device(pdev)) {
+		printk(KERN_ERR "s2io: "
+		       "Cannot re-enable PCI device after reset.\n");
+		return PCI_ERS_RESULT_DISCONNECT;
+	}
+
+	pci_set_master(pdev);
+	s2io_reset(sp);
+
+	return PCI_ERS_RESULT_RECOVERED;
+}
+
+/**
+ * s2io_io_resume - called when traffic can start flowing again.
+ * @pdev: Pointer to PCI device
+ *
+ * This callback is called when the error recovery driver tells
+ * us that its OK to resume normal operation.
+ */
+static void s2io_io_resume(struct pci_dev *pdev)
+{
+	struct net_device *netdev = pci_get_drvdata(pdev);
+	struct s2io_nic *sp = netdev->priv;
+
+	if (netif_running(netdev)) {
+		if (s2io_card_up(sp)) {
+			printk(KERN_ERR "s2io: "
+			       "Can't bring device back up after reset.\n");
+			return;
+		}
+
+		if (s2io_set_mac_addr(netdev, netdev->dev_addr) == FAILURE) {
+			s2io_card_down(sp);
+			printk(KERN_ERR "s2io: "
+			       "Can't resetore mac addr after reset.\n");
+			return;
+		}
+	}
+
+	netif_device_attach(netdev);
+	netif_wake_queue(netdev);
+}
Index: linux-2.6.20-git4/drivers/net/s2io.h
===================================================================
--- linux-2.6.20-git4.orig/drivers/net/s2io.h	2007-02-15 15:39:35.000000000 -0600
+++ linux-2.6.20-git4/drivers/net/s2io.h	2007-02-15 16:59:40.000000000 -0600
@@ -1020,6 +1020,11 @@ static void update_L3L4_header(struct s2
 static void lro_append_pkt(struct s2io_nic *sp, struct lro *lro,
 			   struct sk_buff *skb, u32 tcp_len);
 
+static pci_ers_result_t s2io_io_error_detected(struct pci_dev *pdev,
+			                      pci_channel_state_t state);
+static pci_ers_result_t s2io_io_slot_reset(struct pci_dev *pdev);
+static void s2io_io_resume(struct pci_dev *pdev);
+
 #define s2io_tcp_mss(skb) skb_shinfo(skb)->gso_size
 #define s2io_udp_mss(skb) skb_shinfo(skb)->gso_size
 #define s2io_offload_type(skb) skb_shinfo(skb)->gso_type