linux device driver 源代码

/* * snull.c -- the Simple Network Utility * * Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet * Copyright (C) 2001 O'Reilly & Associates * * The source code in this file can be freely used, adapted, * and redistributed in source or binary form, so long as an * acknowledgment appears in derived source files. The citation * should list that the code comes from the book "Linux Device * Drivers" by Alessandro Rubini and Jonathan Corbet, published * by O'Reilly & Associates. No warranty is attached; * we cannot take responsibility for errors or fitness for use. * * $Id: snull.c,v 1.21 2004/11/05 02:36:03 rubini Exp $ */ #include <linux/config.h> #include <linux/module.h> #include <linux/init.h> #include <linux/moduleparam.h> #include <linux/sched.h> #include <linux/kernel.h> /* printk() */ #include <linux/slab.h> /* kmalloc() */ #include <linux/errno.h> /* error codes */ #include <linux/types.h> /* size_t */ #include <linux/interrupt.h> /* mark_bh */ #include <linux/in.h> #include <linux/netdevice.h> /* struct device, and other headers */ #include <linux/etherdevice.h> /* eth_type_trans */ #include <linux/ip.h> /* struct iphdr */ #include <linux/tcp.h> /* struct tcphdr */ #include <linux/skbuff.h> #include "snull.h" #include <linux/in6.h> #include <asm/checksum.h> MODULE_AUTHOR("Alessandro Rubini, Jonathan Corbet"); MODULE_LICENSE("Dual BSD/GPL"); /* * Transmitter lockup simulation, normally disabled. */ static int lockup = 0; module_param(lockup, int, 0); static int timeout = SNULL_TIMEOUT; module_param(timeout, int, 0); /* * Do we run in NAPI mode? */ static int use_napi = 0; module_param(use_napi, int, 0); /* * A structure representing an in-flight packet. */ struct snull_packet { struct snull_packet *next; struct net_device *dev; int datalen; u8 data[ETH_DATA_LEN]; }; int pool_size = 8; module_param(pool_size, int, 0); /* * This structure is private to each device. It is used to pass * packets in and out, so there is place for a packet */ struct snull_priv { struct net_device_stats stats; int status; struct snull_packet *ppool; struct snull_packet *rx_queue; /* List of incoming packets */ int rx_int_enabled; int tx_packetlen; u8 *tx_packetdata; struct sk_buff *skb; spinlock_t lock; }; static void snull_tx_timeout(struct net_device *dev); static void (*snull_interrupt)(int, void *, struct pt_regs *); /* * Set up a device's packet pool. */ void snull_setup_pool(struct net_device *dev) { struct snull_priv *priv = netdev_priv(dev); int i; struct snull_packet *pkt; priv->ppool = NULL; for (i = 0; i < pool_size; i++) { pkt = kmalloc (sizeof (struct snull_packet), GFP_KERNEL); if (pkt == NULL) { printk (KERN_NOTICE "Ran out of memory allocating packet pool\n"); return; } pkt->dev = dev; pkt->next = priv->ppool; priv->ppool = pkt; } } void snull_teardown_pool(struct net_device *dev) { struct snull_priv *priv = netdev_priv(dev); struct snull_packet *pkt; while ((pkt = priv->ppool)) { priv->ppool = pkt->next; kfree (pkt); /* FIXME - in-flight packets ? */ } } /* * Buffer/pool management. */ struct snull_packet *snull_get_tx_buffer(struct net_device *dev) { struct snull_priv *priv = netdev_priv(dev); unsigned long flags; struct snull_packet *pkt; spin_lock_irqsave(&priv->lock, flags); pkt = priv->ppool; priv->ppool = pkt->next; if (priv->ppool == NULL) { printk (KERN_INFO "Pool empty\n"); netif_stop_queue(dev); } spin_unlock_irqrestore(&priv->lock, flags); return pkt; } void snull_release_buffer(struct snull_packet *pkt) { unsigned long flags; struct snull_priv *priv = netdev_priv(pkt->dev); spin_lock_irqsave(&priv->lock, flags); pkt->next = priv->ppool; priv->ppool = pkt; spin_unlock_irqrestore(&priv->lock, flags); if (netif_queue_stopped(pkt->dev) && pkt->next == NULL) netif_wake_queue(pkt->dev); } void snull_enqueue_buf(struct net_device *dev, struct snull_packet *pkt) { unsigned long flags; struct snull_priv *priv = netdev_priv(dev); spin_lock_irqsave(&priv->lock, flags); pkt->next = priv->rx_queue; /* FIXME - misorders packets */ priv->rx_queue = pkt; spin_unlock_irqrestore(&priv->lock, flags); } struct snull_packet *snull_dequeue_buf(struct net_device *dev) { struct snull_priv *priv = netdev_priv(dev); struct snull_packet *pkt; unsigned long flags; spin_lock_irqsave(&priv->lock, flags); pkt = priv->rx_queue; if (pkt != NULL) priv->rx_queue = pkt->next; spin_unlock_irqrestore(&priv->lock, flags); return pkt; } /* * Enable and disable receive interrupts. */ static void snull_rx_ints(struct net_device *dev, int enable) { struct snull_priv *priv = netdev_priv(dev); priv->rx_int_enabled = enable; } /* * Open and close */ int snull_open(struct net_device *dev) { /* request_region(), request_irq(), .... (like fops->open) */ /* * Assign the hardware address of the board: use "\0SNULx", where * x is 0 or 1. The first byte is '\0' to avoid being a multicast * address (the first byte of multicast addrs is odd). */ memcpy(dev->dev_addr, "\0SNUL0", ETH_ALEN); if (dev == snull_devs[1]) dev->dev_addr[ETH_ALEN-1]++; /* \0SNUL1 */ netif_start_queue(dev); return 0; } int snull_release(struct net_device *dev) { /* release ports, irq and such -- like fops->close */ netif_stop_queue(dev); /* can't transmit any more */ return 0; } /* * Configuration changes (passed on by ifconfig) */ int snull_config(struct net_device *dev, struct ifmap *map) { if (dev->flags & IFF_UP) /* can't act on a running interface */ return -EBUSY; /* Don't allow changing the I/O address */ if (map->base_addr != dev->base_addr) { printk(KERN_WARNING "snull: Can't change I/O address\n"); return -EOPNOTSUPP; } /* Allow changing the IRQ */ if (map->irq != dev->irq) { dev->irq = map->irq; /* request_irq() is delayed to open-time */ } /* ignore other fields */ return 0; } /* * Receive a packet: retrieve, encapsulate and pass over to upper levels */ void snull_rx(struct net_device *dev, struct snull_packet *pkt) { struct sk_buff *skb; struct snull_priv *priv = netdev_priv(dev); /* * The packet has been retrieved from the transmission * medium. Build an skb around it, so upper layers can handle it */ skb = dev_alloc_skb(pkt->datalen + 2); if (!skb) { if (printk_ratelimit()) printk(KERN_NOTICE "snull rx: low on mem - packet dropped\n"); priv->stats.rx_dropped++; goto out; } skb_reserve(skb, 2); /* align IP on 16B boundary */ memcpy(skb_put(skb, pkt->datalen), pkt->data, pkt->datalen); /* Write metadata, and then pass to the receive level */ skb->dev = dev; skb->protocol = eth_type_trans(skb, dev); skb->ip_summed = CHECKSUM_UNNECESSARY; /* don't check it */ priv->stats.rx_packets++; priv->stats.rx_bytes += pkt->datalen; netif_rx(skb); out: return; } /* * The poll implementation. */ static int snull_poll(struct net_device *dev, int *budget) { int npackets = 0, quota = min(dev->quota, *budget); struct sk_buff *skb; struct snull_priv *priv = netdev_priv(dev); struct snull_packet *pkt; while (npackets < quota && priv->rx_queue) { pkt = snull_dequeue_buf(dev); skb = dev_alloc_skb(pkt->datalen + 2); if (! skb) { if (printk_ratelimit()) printk(KERN_NOTICE "snull: packet dropped\n"); priv->stats.rx_dropped++; snull_release_buffer(pkt); continue; } skb_reserve(skb, 2); /* align IP on 16B boundary */ memcpy(skb_put(skb, pkt->datalen), pkt->data, pkt->datalen); skb->dev = dev; skb->protocol = eth_type_trans(skb, dev); skb->ip_summed = CHECKSUM_UNNECESSARY; /* don't check it */ netif_receive_skb(skb); /* Maintain stats */ npackets++; priv->stats.rx_packets++; priv->stats.rx_bytes += pkt->datalen; snull_release_buffer(pkt); } /* If we processed all packets, we're done; tell the kernel and reenable ints */ *budget -= npackets; dev->quota -= npacke