Mini2440 DM9000 驱动分析（一）
硬件特性
Mini2440开发板上DM9000的电气连接和Mach-mini2440.c文件的关系：
PW_RST 连接到复位按键，复位按键按下，低电平触发重新初始化，初始化完成后5us后可以使用（The DM9000 is ready after 5us when this pin deasserted ）
CMD 连接到s3c2440 的ADD2 pin
INT 连接到s3c2440 的EINT7/GPF7，将中断控制端口
LINK_ACT 连接到网络接口的GLEDK pin，连接到LINK LED，这样网卡上面的灯才可以亮
LINK_O、WAKEUP、SPEED100# 这三个pin并联之后连接的网络接口的YLEDK pin
AEN 连接到s3c2440 的nGCS4/GPA15 pin
IOR# 连接到s3c2440 的nOE pin
IOW# 连接到s3c2440 的 nWE pin
IOWAIT 直接通过电阻借电源，即高电平
TXO-、TXO+、RX-、RX+ 直接接到网络端口用于数据收发
SD0-15 连接到s3c2440 的DATA0-15
其中片选信号AEN使用了nGCS4，所以网卡的内存区域在BANK4，也就是从地址0x20000000开始。
DM9000的TXD[2:0]作为strap pin在电路图中是空接的，所以IO base是300H。
中断使用了EINT7。
代码如下：
/* DM9000AEP 10/100 ethernet controller */
#define MACH_MINI2440_DM9K_BASE (S3C2410_CS4 + 0x300)
static struct resource mini2440_dm9k_resource[] = {
[0] = {
.start = MACH_MINI2440_DM9K_BASE,
.end = MACH_MINI2440_DM9K_BASE + 3,
.flags = IORESOURCE_MEM
},
[1] = {
.start = MACH_MINI2440_DM9K_BASE + 4,
.end = MACH_MINI2440_DM9K_BASE + 7,
.flags = IORESOURCE_MEM
},
[2] = {
.start = IRQ_EINT7,
.end = IRQ_EINT7,
.flags = IORESOURCE_IRQ | IORESOURCE_IRQ_HIGHEDGE,
}
};
/*
* * The DM9000 has no eeprom, and it's MAC address is set by
* * the bootloader before starting the kernel.
* */
static struct dm9000_plat_data mini2440_dm9k_pdata = {
.flags = (DM9000_PLATF_16BITONLY | DM9000_PLATF_NO_EEPROM),
};
static struct platform_device mini2440_device_eth = {
.name = "dm9000",
.id = -1,
.num_resources = ARRAY_SIZE(mini2440_dm9k_resource),
.resource = mini2440_dm9k_resource,
.dev = {
.platform_data = &mini2440_dm9k_pdata,
},
};
研究net driver首先就要先了解一下网络驱动编写的一个基本架构
两个重要的结构体简单介绍：sk_buff和net_device
sk_buff
如果把网络传输看成是运送货物的话，那么sk_buff就是这个“货物”了，所有经手这个货物的人都要干点什么事儿，要么加个包装，要么印个戳儿等等。收货的时候就要拆掉这些包装，得到我们需要的货物（payload data）。没有货物你还运输什么呢？由此可见sk_buff的重要性了。
关于sk_buff的详细介绍和几个操作它的函数，参考：“linux内核sk_buff的结构分析” http://www.linuxidc.com/Linux/2011-07/39163.htm，写得非常明白了。赞一个~
net_device
又是一个庞大的结构体。好吧，我承认我从来就没有看全过这个结构体。它在内核中就是指代了一个网络设备。驱动程序需要在探测的时候分配并初始化这个结构体，然后使用register_netdev来注册它，这样就可以把操作硬件的函数与内核挂接在一起。
对于我们来说probe是一切一切的开始，看看dm9000驱动probe需要用要的结构体
board_info
/* Structure/enum declaration ------------------------------- */
typedef struct board_info {
void __iomem *io_addr; /* Register I/O base address */
void __iomem *io_data; /* Data I/O address */
u16 irq; /* IRQ */
u16 tx_pkt_cnt;
u16 queue_pkt_len;
u16 queue_start_addr;
u16 queue_ip_summed;
u16 dbug_cnt;
u8 io_mode; /* 0:word, 2:byte */
u8 phy_addr;
u8 imr_all;
unsigned int flags;
unsigned int in_suspend :1;
int debug_level;
enum dm9000_type type;
void (*inblk)(void __iomem *port, void *data, int length);
void (*outblk)(void __iomem *port, void *data, int length);
void (*dumpblk)(void __iomem *port, int length);
struct device *dev; /* parent device */
struct resource *addr_res; /* resources found */
struct resource *data_res;
struct resource *addr_req; /* resources requested */
struct resource *data_req;
struct resource *irq_res;
struct mutex addr_lock; /* phy and eeprom access lock */
struct delayed_work phy_poll;
struct net_device *ndev;
spinlock_t lock;
struct mii_if_info mii;
u32 msg_enable;
int rx_csum;
int can_csum;
int ip_summed;
} board_info_t;
其中有两个很重要的结构体 net_device 和 mii_if_info
mii_if_info
struct mii_if_info {
int phy_id;
int advertising;
int phy_id_mask;
int reg_num_mask;
unsigned int full_duplex : 1; /* is full duplex? */
unsigned int force_media : 1; /* is autoneg. disabled? */
unsigned int supports_gmii : 1; /* are GMII registers supported? */
struct net_device *dev;
int (*mdio_read) (struct net_device *dev, int phy_id, int location);
void (*mdio_write) (struct net_device *dev, int phy_id, int location, int val);
};
net_device
/*
* The DEVICE structure.
* Actually, this whole structure is a big mistake. It mixes I/O
* data with strictly "high-level" data, and it has to know about
* almost every data structure used in the INET module.
*
* FIXME: cleanup struct net_device such that network protocol info
* moves out.
*/
struct net_device
{
/*
* This is the first field of the "visible" part of this structure
* (i.e. as seen by users in the "Space.c" file). It is the name
* the interface.
*/
char name[IFNAMSIZ];
/* device name hash chain */
struct hlist_node name_hlist;
/* snmp alias */
char *ifalias;
/*
* I/O specific fields
* FIXME: Merge these and struct ifmap into one
*/
unsigned long mem_end; /* shared mem end */
unsigned long mem_start; /* shared mem start */
unsigned long base_addr; /* device I/O address */
unsigned int irq; /* device IRQ number */
/*
* Some hardware also needs these fields, but they are not
* part of the usual set specified in Space.c.
*/
unsigned char if_port; /* Selectable AUI, TP,..*/
unsigned char dma; /* DMA channel */
unsigned long state;
struct list_head dev_list;
struct list_head napi_list;
/* Net device features */
unsigned long features;
#define NETIF_F_SG 1 /* Scatter/gather IO. */
#define NETIF_F_IP_CSUM 2 /* Can checksum TCP/UDP over IPv4. */
#define NETIF_F_NO_CSUM 4 /* Does not require checksum. F.e. loopack. */
#define NETIF_F_HW_CSUM 8 /* Can checksum all the packets. */
#define NETIF_F_IPV6_CSUM 16 /* Can checksum TCP/UDP over IPV6 */
#define NETIF_F_HIGHDMA 32 /* Can DMA to high memory. */
#define NETIF_F_FRAGLIST 64 /* Scatter/gather IO. */
#define NETIF_F_HW_VLAN_TX 128 /* Transmit VLAN hw acceleration */
#define NETIF_F_HW_VLAN_RX 256 /* Receive VLAN hw acceleration */
#define NETIF_F_HW_VLAN_FILTER 512 /* Receive filtering on VLAN */
#define NETIF_F_VLAN_CHALLENGED 1024 /* Device cannot handle VLAN packets */
#define NETIF_F_GSO 2048 /* Enable software GSO. */
#define NETIF_F_LLTX 4096 /* LockLess TX - deprecated. Please */
/* do not use LLTX in new drivers */
#define NETIF_F_NETNS_LOCAL 8192 /* Does not change network namespaces */
#define NETIF_F_GRO 16384 /* Generic receive offload */
#define NETIF_F_LRO 32768 /* large receive offload */
/* the GSO_MASK reserves bits 16 through 23 */
#define NETIF_F_FCOE_CRC (1 << 24) /* FCoE CRC32 */
#define NETIF_F_SCTP_CSUM (1 << 25) /* SCTP checksum offload */
#define NETIF_F_FCOE_MTU (1 << 26) /* Supports max FCoE MTU, 2158 bytes*/
/* Segmentation offload features */
#define NETIF_F_GSO_SHIFT 16
#define NETIF_F_GSO_MASK 0x00ff0000
#define NETIF_F_TSO (SKB_GSO_TCPV4 << NETIF_F_GSO_SHIFT)
#define NETIF_F_UFO (SKB_GSO_UDP << NETIF_F_GSO_SHIFT)
#define NETIF_F_GSO_ROBUST (SKB_GSO_DODGY << NETIF_F_GSO_SHIFT)
#define NETIF_F_TSO_ECN (SKB_GSO_TCP_ECN << NETIF_F_GSO_SHIFT)
#define NETIF_F_TSO6 (SKB_GSO_TCPV6 << NETIF_F_GSO_SHIFT)
#define NETIF_F_FSO (SKB_GSO_FCOE << NETIF_F_GSO_SHIFT)
/* List of features with software fallbacks. */
#define NETIF_F_GSO_SOFTWARE (NETIF_F_TSO | NETIF_F_TSO_ECN | NETIF_F_TSO6)
#define NETIF_F_GEN_CSUM (NETIF_F_NO_CSUM | NETIF_F_HW_CSUM)
#define NETIF_F_V4_CSUM (NETIF_F_GEN_CSUM | NETIF_F_IP_CSUM)
#define NETIF_F_V6_CSUM (NETIF_F_GEN_CSUM | NETIF_F_IPV6_CSUM)
#define NETIF_F_ALL_CSUM (NETIF_F_V4_CSUM | NETIF_F_V6_CSUM)
/*
* If one device supports one of these features, then enable them
* for all in netdev_increment_features.
*/
#define NETIF_F_ONE_FOR_ALL (NETIF_F_GSO_SOFTWARE | NETIF_F_GSO_ROBUST | \
NETIF_F_SG | NETIF_F_HIGHDMA | \
NETIF_F_FRAGLIST)
/* Interface index. Unique device identifier */
int ifindex;
int iflink;
struct net_device_stats stats;
#ifdef CONFIG_WIRELESS_EXT
/* List of functions to handle Wireless Extensions (instead of ioctl).
* See
const struct iw_handler_def * wireless_handlers;
/* Instance data managed by the core of Wireless Extensions. */
struct iw_public_data * wireless_data;
#endif
/* Management operations */
const struct net_device_ops *netdev_ops;
const struct ethtool_ops *ethtool_ops;
/* Hardware header description */
const struct header_ops *header_ops;
unsigned int flags; /* interface flags (a la BSD) */
unsigned short gflags;
unsigned short priv_flags; /* Like 'flags' but invisible to userspace. */
unsigned short padded; /* How much padding added by alloc_netdev() */
unsigned char operstate; /* RFC2863 operstate */
unsigned char link_mode; /* mapping policy to operstate */
unsigned mtu; /* interface MTU value */
unsigned short type; /* interface hardware type */
unsigned short hard_header_len; /* hardware hdr length */
/* extra head- and tailroom the hardware may need, but not in all cases
* can this be guaranteed, especially tailroom. Some cases also use
* LL_MAX_HEADER instead to allocate the skb.
*/
unsigned short needed_headroom;
unsigned short needed_tailroom;
struct net_device *master; /* Pointer to master device of a group,
* which this device is member of.
*/
/* Interface address info. */
unsigned char perm_addr[MAX_ADDR_LEN]; /* permanent hw address */
unsigned char addr_len; /* hardware address length */
unsigned short dev_id; /* for shared network cards */
struct netdev_hw_addr_list uc; /* Secondary unicast
mac addresses */
int uc_promisc;
spinlock_t addr_list_lock;
struct dev_addr_list *mc_list; /* Multicast mac addresses */
int mc_count; /* Number of installed mcasts */
unsigned int promiscuity;
unsigned int allmulti;
/* Protocol specific pointers */
#ifdef CONFIG_NET_DSA
void *dsa_ptr; /* dsa specific data */
#endif
void *atalk_ptr; /* AppleTalk link */
void *ip_ptr; /* IPv4 specific data */
void *dn_ptr; /* DECnet specific data */
void *ip6_ptr; /* IPv6 specific data */
void *ec_ptr; /* Econet specific data */
void *ax25_ptr; /* AX.25 specific data */
struct wireless_dev *ieee80211_ptr; /* IEEE 802.11 specific data,
assign before registering */
/*
* Cache line mostly used on receive path (including eth_type_trans())
*/
unsigned long last_rx; /* Time of last Rx */
/* Interface address info used in eth_type_trans() */
unsigned char *dev_addr; /* hw address, (before bcast
because most packets are
unicast) */
struct netdev_hw_addr_list dev_addrs; /* list of device
hw addresses */
unsigned char broadcast[MAX_ADDR_LEN]; /* hw bcast add */
struct netdev_queue rx_queue;
struct netdev_queue *_tx ____cacheline_aligned_in_smp;
/* Number of TX queues allocated at alloc_netdev_mq() time */
unsigned int num_tx_queues;
/* Number of TX queues currently active in device */
unsigned int real_num_tx_queues;
/* root qdisc from userspace point of view */
struct Qdisc *qdisc;
unsigned long tx_queue_len; /* Max frames per queue allowed */
spinlock_t tx_global_lock;
/*
* One part is mostly used on xmit path (device)
*/
/* These may be needed for future network-power-down code. */
/*
* trans_start here is expensive for high speed devices on SMP,
* please use netdev_queue->trans_start instead.
*/
unsigned long trans_start; /* Time (in jiffies) of last Tx */
int watchdog_timeo; /* used by dev_watchdog() */
struct timer_list watchdog_timer;
/* Number of references to this device */
atomic_t refcnt ____cacheline_aligned_in_smp;
/* delayed register/unregister */
struct list_head todo_list;
/* device index hash chain */
struct hlist_node index_hlist;
struct net_device *link_watch_next;
/* register/unregister state machine */
enum { NETREG_UNINITIALIZED=0,
NETREG_REGISTERED, /* completed register_netdevice */
NETREG_UNREGISTERING, /* called unregister_netdevice */
NETREG_UNREGISTERED, /* completed unregister todo */
NETREG_RELEASED, /* called free_netdev */
NETREG_DUMMY, /* dummy device for NAPI poll */
} reg_state;
/* Called from unregister, can be used to call free_netdev */
void (*destructor)(struct net_device *dev);
#ifdef CONFIG_NETPOLL
struct netpoll_info *npinfo;
#endif
#ifdef CONFIG_NET_NS
/* Network namespace this network device is inside */
struct net *nd_net;
#endif
/* mid-layer private */
void *ml_priv;
/* bridge stuff */
struct net_bridge_port *br_port;
/* macvlan */
struct macvlan_port *macvlan_port;
/* GARP */
struct garp_port *garp_port;
/* class/net/name entry */
struct device dev;
/* space for optional statistics and wireless sysfs groups */
const struct attribute_group *sysfs_groups[3];
/* rtnetlink link ops */
const struct rtnl_link_ops *rtnl_link_ops;
/* VLAN feature mask */
unsigned long vlan_features;
/* for setting kernel sock attribute on TCP connection setup */
#define GSO_MAX_SIZE 65536
unsigned int gso_max_size;
#ifdef CONFIG_DCB
/* Data Center Bridging netlink ops */
struct dcbnl_rtnl_ops *dcbnl_ops;
#endif
#if defined(CONFIG_FCOE) || defined(CONFIG_FCOE_MODULE)
/* max exchange id for FCoE LRO by ddp */
unsigned int fcoe_ddp_xid;
#endif
};
确实是如此庞大的一个结构体，让人畏惧的感觉，饭要一口一口吃啊O(∩_∩)O~
另外，还是认识一下另一个上面提到的庞大结构体吧，sk_buff
/**
* struct sk_buff - socket buffer
* @next: Next buffer in list
* @prev: Previous buffer in list
* @sk: Socket we are owned by
* @tstamp: Time we arrived
* @dev: Device we arrived on/are leaving by
* @transport_header: Transport layer header
* @network_header: Network layer header
* @mac_header: Link layer header
* @_skb_dst: destination entry
* @sp: the security path, used for xfrm
* @cb: Control buffer. Free for use by every layer. Put private vars here
* @len: Length of actual data
* @data_len: Data length
* @mac_len: Length of link layer header
* @hdr_len: writable header length of cloned skb
* @csum: Checksum (must include start/offset pair)
* @csum_start: Offset from skb->head where checksumming should start
* @csum_offset: Offset from csum_start where checksum should be stored
* @local_df: allow local fragmentation
* @cloned: Head may be cloned (check refcnt to be sure)
* @nohdr: Payload reference only, must not modify header
* @pkt_type: Packet class
* @fclone: skbuff clone status
* @ip_summed: Driver fed us an IP checksum
* @priority: Packet queueing priority
* @users: User count - see {datagram,tcp}.c
* @protocol: Packet protocol from driver
* @truesize: Buffer size
* @head: Head of buffer
* @data: Data head pointer
* @tail: Tail pointer
* @end: End pointer
* @destructor: Destruct function
* @mark: Generic packet mark
* @nfct: Associated connection, if any
* @ipvs_property: skbuff is owned by ipvs
* @peeked: this packet has been seen already, so stats have been
* done for it, don't do them again
* @nf_trace: netfilter packet trace flag
* @nfctinfo: Relationship of this skb to the connection
* @nfct_reasm: netfilter conntrack re-assembly pointer
* @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
* @iif: ifindex of device we arrived on
* @queue_mapping: Queue mapping for multiqueue devices
* @tc_index: Traffic control index
* @tc_verd: traffic control verdict
* @ndisc_nodetype: router type (from link layer)
* @dma_cookie: a cookie to one of several possible DMA operations
* done by skb DMA functions
* @secmark: security marking
* @vlan_tci: vlan tag control information
*/
struct sk_buff {
/* These two members must be first. */
struct sk_buff *next;
struct sk_buff *prev;
struct sock *sk;
ktime_t tstamp;
struct net_device *dev;
unsigned long _skb_dst;
#ifdef CONFIG_XFRM
struct sec_path *sp;
#endif
/*
* This is the control buffer. It is free to use for every
* layer. Please put your private variables there. If you
* want to keep them across layers you have to do a skb_clone()
* first. This is owned by whoever has the skb queued ATM.
*/
char cb[48];
unsigned int len,
data_len;
__u16 mac_len,
hdr_len;
union {
__wsum csum;
struct {
__u16 csum_start;
__u16 csum_offset;
};
};
__u32 priority;
kmemcheck_bitfield_begin(flags1);
__u8 local_df:1,
cloned:1,
ip_summed:2,
nohdr:1,
nfctinfo:3;
__u8 pkt_type:3,
fclone:2,
ipvs_property:1,
peeked:1,
nf_trace:1;
__be16 protocol:16;
kmemcheck_bitfield_end(flags1);
void (*destructor)(struct sk_buff *skb);
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
struct nf_conntrack *nfct;
struct sk_buff *nfct_reasm;
#endif
#ifdef CONFIG_BRIDGE_NETFILTER
struct nf_bridge_info *nf_bridge;
#endif
int iif;
#ifdef CONFIG_NET_SCHED
__u16 tc_index; /* traffic control index */
#ifdef CONFIG_NET_CLS_ACT
__u16 tc_verd; /* traffic control verdict */
#endif
#endif
kmemcheck_bitfield_begin(flags2);
__u16 queue_mapping:16;
#ifdef CONFIG_IPV6_NDISC_NODETYPE
__u8 ndisc_nodetype:2;
#endif
kmemcheck_bitfield_end(flags2);
/* 0/14 bit hole */
#ifdef CONFIG_NET_DMA
dma_cookie_t dma_cookie;
#endif
#ifdef CONFIG_NETWORK_SECMARK
__u32 secmark;
#endif
__u32 mark;
__u16 vlan_tci;
sk_buff_data_t transport_header;
sk_buff_data_t network_header;
sk_buff_data_t mac_header;
/* These elements must be at the end, see alloc_skb() for details. */
sk_buff_data_t tail;
sk_buff_data_t end;
unsigned char *head,
*data;
unsigned int truesize;
atomic_t users;
};
看到这是结构，让我深深感觉到彻底理清网卡驱动的编写还需要好好下一番功夫，莫要小看了它啊
下面会开始具体分析网卡驱动的整个probe过程，很关键的知识点。。。。
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