2021年11月09日 | 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 for details. Jean II */

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