[PATCH] natsemi: NAPI and a bugfix

This patch converts the natsemi driver to use NAPI.  It was originally
based on one written by Harald Welte, though it has since been modified
quite a bit, most extensively in order to remove the ability to disable
NAPI since none of the other drivers seem to provide that functionality
any more.

Signed-off-by: Mark Brown <broonie@sirena.org.uk>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 97 insertions, 49 deletions

diff --git a/drivers/net/natsemi.c b/drivers/net/natsemi.c
index 01920648fc38..e363f9bb35ea 100644
--- a/drivers/net/natsemi.c
+++ b/drivers/net/natsemi.c
@@ -3,6 +3,7 @@
         Written/copyright 1999-2001 by Donald Becker.
         Portions copyright (c) 2001,2002 Sun Microsystems (thockin@sun.com)
         Portions copyright 2001,2002 Manfred Spraul (manfred@colorfullife.com)
+        Portions copyright 2004 Harald Welte <laforge@gnumonks.org>
 
         This software may be used and distributed according to the terms of
         the GNU General Public License (GPL), incorporated herein by reference.
@@ -135,8 +136,6 @@
 
         TODO:
         * big endian support with CFG:BEM instead of cpu_to_le32
-        * support for an external PHY
-        * NAPI
 */
 
 #include <linux/config.h>
@@ -160,6 +159,7 @@
 #include <linux/mii.h>
 #include <linux/crc32.h>
 #include <linux/bitops.h>
+#include <linux/prefetch.h>
 #include <asm/processor.h>      /* Processor type for cache alignment. */
 #include <asm/io.h>
 #include <asm/irq.h>
@@ -183,8 +183,6 @@
                                  NETIF_MSG_TX_ERR)
 static int debug = -1;
 
-/* Maximum events (Rx packets, etc.) to handle at each interrupt. */
-static int max_interrupt_work = 20;
 static int mtu;
 
 /* Maximum number of multicast addresses to filter (vs. rx-all-multicast).
@@ -251,14 +249,11 @@ MODULE_AUTHOR("Donald Becker <becker@scyld.com>");
 MODULE_DESCRIPTION("National Semiconductor DP8381x series PCI Ethernet driver");
 MODULE_LICENSE("GPL");
 
-module_param(max_interrupt_work, int, 0);
 module_param(mtu, int, 0);
 module_param(debug, int, 0);
 module_param(rx_copybreak, int, 0);
 module_param_array(options, int, NULL, 0);
 module_param_array(full_duplex, int, NULL, 0);
-MODULE_PARM_DESC(max_interrupt_work, 
-        "DP8381x maximum events handled per interrupt");
 MODULE_PARM_DESC(mtu, "DP8381x MTU (all boards)");
 MODULE_PARM_DESC(debug, "DP8381x default debug level");
 MODULE_PARM_DESC(rx_copybreak, 
@@ -691,6 +686,8 @@ struct netdev_private {
         /* Based on MTU+slack. */
         unsigned int rx_buf_sz;
         int oom;
+        /* Interrupt status */
+        u32 intr_status;
         /* Do not touch the nic registers */
         int hands_off;
         /* external phy that is used: only valid if dev->if_port != PORT_TP */
@@ -748,7 +745,8 @@ static void init_registers(struct net_device *dev);
 static int start_tx(struct sk_buff *skb, struct net_device *dev);
 static irqreturn_t intr_handler(int irq, void *dev_instance, struct pt_regs *regs);
 static void netdev_error(struct net_device *dev, int intr_status);
-static void netdev_rx(struct net_device *dev);
+static int natsemi_poll(struct net_device *dev, int *budget);
+static void netdev_rx(struct net_device *dev, int *work_done, int work_to_do);
 static void netdev_tx_done(struct net_device *dev);
 static int natsemi_change_mtu(struct net_device *dev, int new_mtu);
 #ifdef CONFIG_NET_POLL_CONTROLLER
@@ -776,6 +774,18 @@ static inline void __iomem *ns_ioaddr(struct net_device *dev)
         return (void __iomem *) dev->base_addr;
 }
 
+static inline void natsemi_irq_enable(struct net_device *dev)
+{
+        writel(1, ns_ioaddr(dev) + IntrEnable);
+        readl(ns_ioaddr(dev) + IntrEnable);
+}
+
+static inline void natsemi_irq_disable(struct net_device *dev)
+{
+        writel(0, ns_ioaddr(dev) + IntrEnable);
+        readl(ns_ioaddr(dev) + IntrEnable);
+}
+
 static void move_int_phy(struct net_device *dev, int addr)
 {
         struct netdev_private *np = netdev_priv(dev);
@@ -879,6 +889,7 @@ static int __devinit natsemi_probe1 (struct pci_dev *pdev,
         spin_lock_init(&np->lock);
         np->msg_enable = (debug >= 0) ? (1<<debug)-1 : NATSEMI_DEF_MSG;
         np->hands_off = 0;
+        np->intr_status = 0;
 
         /* Initial port:
          * - If the nic was configured to use an external phy and if find_mii
@@ -932,6 +943,9 @@ static int __devinit natsemi_probe1 (struct pci_dev *pdev,
         dev->do_ioctl = &netdev_ioctl;
         dev->tx_timeout = &tx_timeout;
         dev->watchdog_timeo = TX_TIMEOUT;
+        dev->poll = natsemi_poll;
+        dev->weight = 64;
+
 #ifdef CONFIG_NET_POLL_CONTROLLER
         dev->poll_controller = &natsemi_poll_controller;
 #endif
@@ -2158,68 +2172,92 @@ static void netdev_tx_done(struct net_device *dev)
         }
 }
 
-/* The interrupt handler does all of the Rx thread work and cleans up
-   after the Tx thread. */
+/* The interrupt handler doesn't actually handle interrupts itself, it
+ * schedules a NAPI poll if there is anything to do. */
 static irqreturn_t intr_handler(int irq, void *dev_instance, struct pt_regs *rgs)
 {
         struct net_device *dev = dev_instance;
         struct netdev_private *np = netdev_priv(dev);
         void __iomem * ioaddr = ns_ioaddr(dev);
-        int boguscnt = max_interrupt_work;
-        unsigned int handled = 0;
 
         if (np->hands_off)
                 return IRQ_NONE;
-        do {
-                /* Reading automatically acknowledges all int sources. */
-                u32 intr_status = readl(ioaddr + IntrStatus);
+        
+        /* Reading automatically acknowledges. */
+        np->intr_status = readl(ioaddr + IntrStatus);
 
-                if (netif_msg_intr(np))
-                        printk(KERN_DEBUG
-                                "%s: Interrupt, status %#08x, mask %#08x.\n",
-                                dev->name, intr_status,
-                                readl(ioaddr + IntrMask));
+        if (netif_msg_intr(np))
+                printk(KERN_DEBUG
+                       "%s: Interrupt, status %#08x, mask %#08x.\n",
+                       dev->name, np->intr_status,
+                       readl(ioaddr + IntrMask));
 
-                if (intr_status == 0)
-                        break;
-                handled = 1;
+        if (!np->intr_status) 
+                return IRQ_NONE;
 
-                if (intr_status &
-                   (IntrRxDone | IntrRxIntr | RxStatusFIFOOver |
-                    IntrRxErr | IntrRxOverrun)) {
-                        netdev_rx(dev);
-                }
+        prefetch(&np->rx_skbuff[np->cur_rx % RX_RING_SIZE]);
+
+        if (netif_rx_schedule_prep(dev)) {
+                /* Disable interrupts and register for poll */
+                natsemi_irq_disable(dev);
+                __netif_rx_schedule(dev);
+        }
+        return IRQ_HANDLED;
+}
+
+/* This is the NAPI poll routine.  As well as the standard RX handling
+ * it also handles all other interrupts that the chip might raise.
+ */
+static int natsemi_poll(struct net_device *dev, int *budget)
+{
+        struct netdev_private *np = netdev_priv(dev);
+        void __iomem * ioaddr = ns_ioaddr(dev);
 
-                if (intr_status &
-                   (IntrTxDone | IntrTxIntr | IntrTxIdle | IntrTxErr)) {
+        int work_to_do = min(*budget, dev->quota);
+        int work_done = 0;
+
+        do {
+                if (np->intr_status &
+                    (IntrTxDone | IntrTxIntr | IntrTxIdle | IntrTxErr)) {
                         spin_lock(&np->lock);
                         netdev_tx_done(dev);
                         spin_unlock(&np->lock);
                 }
 
                 /* Abnormal error summary/uncommon events handlers. */
-                if (intr_status & IntrAbnormalSummary)
-                        netdev_error(dev, intr_status);
-
-                if (--boguscnt < 0) {
-                        if (netif_msg_intr(np))
-                                printk(KERN_WARNING
-                                        "%s: Too much work at interrupt, "
-                                        "status=%#08x.\n",
-                                        dev->name, intr_status);
-                        break;
+                if (np->intr_status & IntrAbnormalSummary)
+                        netdev_error(dev, np->intr_status);
+                
+                if (np->intr_status &
+                    (IntrRxDone | IntrRxIntr | RxStatusFIFOOver |
+                     IntrRxErr | IntrRxOverrun)) {
+                        netdev_rx(dev, &work_done, work_to_do);
                 }
-        } while (1);
+                
+                *budget -= work_done;
+                dev->quota -= work_done;
 
-        if (netif_msg_intr(np))
-                printk(KERN_DEBUG "%s: exiting interrupt.\n", dev->name);
+                if (work_done >= work_to_do)
+                        return 1;
+
+                np->intr_status = readl(ioaddr + IntrStatus);
+        } while (np->intr_status);
 
-        return IRQ_RETVAL(handled);
+        netif_rx_complete(dev);
+
+        /* Reenable interrupts providing nothing is trying to shut
+         * the chip down. */
+        spin_lock(&np->lock);
+        if (!np->hands_off && netif_running(dev))
+                natsemi_irq_enable(dev);
+        spin_unlock(&np->lock);
+
+        return 0;
 }
 
 /* This routine is logically part of the interrupt handler, but separated
    for clarity and better register allocation. */
-static void netdev_rx(struct net_device *dev)
+static void netdev_rx(struct net_device *dev, int *work_done, int work_to_do)
 {
         struct netdev_private *np = netdev_priv(dev);
         int entry = np->cur_rx % RX_RING_SIZE;
@@ -2237,6 +2275,12 @@ static void netdev_rx(struct net_device *dev)
                                 entry, desc_status);
                 if (--boguscnt < 0)
                         break;
+
+                if (*work_done >= work_to_do)
+                        break;
+
+                (*work_done)++;
+
                 pkt_len = (desc_status & DescSizeMask) - 4;
                 if ((desc_status&(DescMore|DescPktOK|DescRxLong)) != DescPktOK){
                         if (desc_status & DescMore) {
@@ -2293,7 +2337,7 @@ static void netdev_rx(struct net_device *dev)
                                 np->rx_skbuff[entry] = NULL;
                         }
                         skb->protocol = eth_type_trans(skb, dev);
-                        netif_rx(skb);
+                        netif_receive_skb(skb);
                         dev->last_rx = jiffies;
                         np->stats.rx_packets++;
                         np->stats.rx_bytes += pkt_len;
@@ -3074,9 +3118,7 @@ static int netdev_close(struct net_device *dev)
         del_timer_sync(&np->timer);
         disable_irq(dev->irq);
         spin_lock_irq(&np->lock);
-        /* Disable interrupts, and flush posted writes */
-        writel(0, ioaddr + IntrEnable);
-        readl(ioaddr + IntrEnable);
+        natsemi_irq_disable(dev);
         np->hands_off = 1;
         spin_unlock_irq(&np->lock);
         enable_irq(dev->irq);
@@ -3158,6 +3200,9 @@ static void __devexit natsemi_remove1 (struct pci_dev *pdev)
  *      * netdev_timer: timer stopped by natsemi_suspend.
  *      * intr_handler: doesn't acquire the spinlock. suspend calls
  *              disable_irq() to enforce synchronization.
+ *      * natsemi_poll: checks before reenabling interrupts.  suspend
+ *              sets hands_off, disables interrupts and then waits with
+ *              netif_poll_disable().
  *
  * Interrupts must be disabled, otherwise hands_off can cause irq storms.
  */
@@ -3183,6 +3228,8 @@ static int natsemi_suspend (struct pci_dev *pdev, pm_message_t state)
                 spin_unlock_irq(&np->lock);
                 enable_irq(dev->irq);
 
+                netif_poll_disable(dev);
+
                 /* Update the error counts. */
                 __get_stats(dev);
 
@@ -3235,6 +3282,7 @@ static int natsemi_resume (struct pci_dev *pdev)
                 mod_timer(&np->timer, jiffies + 1*HZ);
         }
         netif_device_attach(dev);
+        netif_poll_enable(dev);
 out:
         rtnl_unlock();
         return 0;