源码来自lpc32xx_mii.c
1. 模块初始化卸载
static int __init lpc32xx_net_init(void)
{
return platform_driver_register(&lpc32xx_net_driver);
}
static void __exit lpc32xx_net_cleanup(void)
{
platform_driver_unregister(&lpc32xx_net_driver);
}
2. 平台驱动相关方法
static struct platform_driver lpc32xx_net_driver = {
.probe = lpc32xx_net_drv_probe,
.remove = __devexit_p(lpc32xx_net_drv_remove),
.suspend = lpc32xx_net_drv_suspend,
.resume = lpc32xx_net_drv_resume,
.driver = {
.name = MODNAME,
},
};
3. probe方法分析
static int lpc32xx_net_drv_probe(struct platform_device *pdev)
{
struct resource *res;
struct net_device *ndev;
struct netdata_local *pldat;
struct phy_device *phydev;
dma_addr_t dma_handle;
int irq, ret;
第一步：从平台上获取资源信息
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
irq = platform_get_irq(pdev, 0);
/*static struct resource net_resources[] = {
[0] = {
.start = ETHERNET_BASE,
.end = ETHERNET_BASE + SZ_4K - 1,
.flags = IORESOURCE_MEM,
},
[1] = {
.start = IRQ_ETHERNET,
.end = IRQ_ETHERNET,
.flags = IORESOURCE_IRQ,
},
};*/
if ((!res) || (irq < 0) || (irq >= NR_IRQS))
{
dev_err(&pdev->dev, "error getting resources.\n");
ret = -ENXIO;
goto err_exit;
}
第二步：分配和初始化net_device结构，这一步也可放在模块初始化中完成
ndev = alloc_etherdev(sizeof(struct netdata_local));
/*alloc_etherdev函数最终调用alloc_netdev_mq(sizeof_priv, "eth%d", ether_setup, queue_count);函数*/
if (!ndev) {
dev_err(&pdev->dev, "could not allocate device.\n");
ret = -ENOMEM;
goto err_exit;
}
SET_NETDEV_DEV(ndev, &pdev->dev);
/*将ndev的父设备指向平台设备。即将ndev设备挂到平台设备表里*/
pldat = netdev_priv(ndev);
//获得ndev的私有指针，指针内的成员由驱动作者自己定义。
pldat->pdev = pdev;
pldat->ndev = ndev;
spin_lock_init(&pldat->lock);
/* Save resources */
pldat->net_region_start = res->start;
pldat->net_region_size = res->end - res->start + 1;
ndev->irq = irq;
//第三步：申请硬件资源
/* Get clock for the device */
pldat->clk = clk_get(&ndev->dev, "net_ck");
if (IS_ERR(pldat->clk)) {
ret = PTR_ERR(pldat->clk);
goto err_out_free_dev;
}
/*以上为初始化私有结构体*/
/* Enable network clock */
__lpc32xx_net_clock_enable(pldat, 1);
//使能时钟
/* Map IO space */
pldat->net_base = ioremap(pldat->net_region_start, pldat->net_region_size);
if (!pldat->net_base)
{
dev_err(&pdev->dev, "failed to map registers, aborting.\n");
ret = -ENOMEM;
goto err_out_disable_clocks;
}
//将网卡物理空间动态映射到内核空间。
ret = request_irq(ndev->irq, __lpc32xx_eth_interrupt, 0,
ndev->name, ndev);
if (ret) {
printk(KERN_ERR
"%s: Unable to request IRQ %d (error %d)\n",
ndev->name, ndev->irq, ret);
goto err_out_iounmap;
}
//申请中断
//第四步：设备操作接口初始化
/* Fill in the fields of the device structure with ethernet values. */
ether_setup(ndev);
/*ndev申请完之后并没有初始化，ether_setup()函数就是完成ndev有关于以太网确定成员的初始化*/
/*probe的以上部分完成了网络设备驱动的“网络设备接口层”的工作，以下对设备操作函数的具体实现便是“设备驱动功能层”的事情，即网络设备驱动的主体工作*/
/* Setup driver functions */
ndev->open = lpc32xx_net_open;
ndev->stop = lpc32xx_net_close;
//设备打开与关闭时调用
ndev->hard_start_xmit = lpc32xx_net_hard_start_xmit;
//设备数据发送时调用
ndev->tx_timeout = lpc32xx_net_timeout;
//发送超时调用
ndev->watchdog_timeo = msecs_to_jiffies(watchdog);
//设定超时时间，单位jiffies
ndev->set_multicast_list = lpc32xx_net_set_multicast_list;
/*当设备的组播列表改变或设备标志改变时调用*/
ndev->ethtool_ops = &lpc32xx_net_ethtool_ops;
//结构体中的成员用于更改或报告网络设备的设置
ndev->do_ioctl = &lpc32xx_net_ioctl;
//设备特定的I/O控制
#ifdef CONFIG_NET_POLL_CONTROLLER
ndev->poll_controller = lpc32xx_net_poll_controller;
//支持纯粹的netconsole(用于kgdb调试)，它以轮询方式接收数据包
#endif
ndev->base_addr = pldat->net_region_start;
// 继续初始化ndev:虚拟基地址
//第五步：其它及DMA初始化
/* Save board specific configuration */
pldat->ncfg = (struct lpc32xx_net_cfg *) pdev->dev.platform_data;
/* .platform_data = &lpc32xx_netdata,
struct lpc32xx_net_cfg lpc32xx_netdata =
{
.get_mac_addr = &return_mac_address,
.phy_irq = -1,
.phy_mask = 0xFFFFFFF0,
};
*/
if (pldat->ncfg == NULL)
{
printk(KERN_INFO "%s : WARNING: No board MAC address provided\n",
ndev->name);
pldat->ncfg = &__lpc32xx_local_net_config;
}
/* Get size of DMA buffers/descriptors region */
pldat->dma_buff_size = (ENET_TX_DESC + ENET_RX_DESC) * (ENET_MAXF_SIZE +
sizeof(struct txrx_desc_t) + sizeof(struct rx_status_t));
/*计算DMA缓冲区所需要的空间，DMA空间包括帧片断（描述符）数组大小，状态大小，帧片断数量*/
#if defined(CONFIG_MACH_LPC32XX_IRAM_FOR_NET)
pldat->dma_buff_base_v = (u32) io_p2v(IRAM_BASE);
dma_handle = (dma_addr_t) IRAM_BASE;
//初始化DMA缓冲区的基地址
#else
pldat->dma_buff_size += 4096; /* Allows room for alignment */
/* Align on the next highest page entry size */
pldat->dma_buff_size &= 0Xfffff000;
pldat->dma_buff_size += 0X00001000;
//如果DMA缓冲区不在内部RAM中，则进行页对齐
/* Allocate a chunk of memory for the DMA ethernet buffers and descriptors */
pldat->dma_buff_base_v = (u32) dma_alloc_coherent(&pldat->pdev->dev, pldat->dma_buff_size,
&dma_handle, GFP_KERNEL);
#endif
//申请一致性缓冲区，初始化DMA缓冲区的基地址
if (pldat->dma_buff_base_v == (u32) NULL)
{
dev_err(&pdev->dev, "error getting DMA region.\n");
ret = -ENOMEM;
goto err_out_free_irq;
}
pldat->dma_buff_base_p = (u32) dma_handle;
#ifdef NET_DEBUG
printk(KERN_INFO "Ethernet net MAC resources\n");
printk(KERN_INFO "IO address start :0x%08x\n", (u32) pldat->net_region_start);
printk(KERN_INFO "IO address size :%d\n", (u32) pldat->net_region_size);
printk(KERN_INFO "IO address (mapped) :0x%08x\n", (u32) pldat->net_base);
printk(KERN_INFO "IRQ number :%d\n", ndev->irq);
printk(KERN_INFO "DMA buffer size :%d\n", pldat->dma_buff_size);
printk(KERN_INFO "DMA buffer P address :0x%08x\n", pldat->dma_buff_base_p);
printk(KERN_INFO "DMA buffer V address :0x%08x\n", pldat->dma_buff_base_v);
#endif
/* Get the board MAC address */
if (pldat->ncfg->get_mac_addr != NULL)
{
ret = pldat->ncfg->get_mac_addr(ndev->dev_addr);
//在探测阶段先随便指定一个mac完成初始化
if (ret)
{
/* Mac address load error */
goto err_out_dma_unmap;
}
}
if (!is_valid_ether_addr(ndev->dev_addr))
{
printk(KERN_INFO "%s: Invalid ethernet MAC address. Please "
"set using ifconfig\n", ndev->name);
}
第六步：以太网控制器相关
/* Reset the ethernet controller */
__lpc32xx_eth_reset(pldat);
//__lpc32xx_eth_reset()函数是一些读写寄存器构成
/* then shut everything down to save power */
__lpc32xx_net_shutdown(pldat);
/* Set default parameters */
pldat->msg_enable = NETIF_MSG_LINK;
/* Force an MII interface reset and clock setup */
__lpc32xx_mii_mngt_reset(pldat);
/* Force default PHY interface setup in chip, this will probably be
changed by the PHY driver */
pldat->link = 0;
pldat->speed = 100;
pldat->duplex = DUPLEX_FULL;
__lpc32xx_params_setup(pldat);
//__lpc32xx_params_setup()函数就是根据pldat的speed,duplex设置完成相应寄存器设置。
ret = register_netdev(ndev);
//以上代码主要就是完成了ndev及其私有指针pldat指向结构的部分初始化
if (ret) {
dev_err(&pdev->dev, "Cannot register net device, aborting.\n");
goto err_out_dma_unmap;
}
platform_set_drvdata(pdev, ndev);
//将ndev作为pdev->drvdata,方便pdev与ndev之间结构信息共享
if (lpc32xx_mii_init(pldat) != 0) {
goto err_out_unregister_netdev;
}
// lpc32xx_mii_init()完成mii接口的初始化见“lpc32xx_mii_init()函数分析”
printk(KERN_INFO "%s: LPC32XX mac at 0x%08lx irq %d\n",
ndev->name, ndev->base_addr, ndev->irq);
//最后初始化了一个总线设备。下面的是一些错误处理。
phydev = pldat->phy_dev;
printk(KERN_INFO "%s: attached PHY driver [%s] "
"(mii_bus:phy_addr=%s, irq=%d)\n",
ndev->name, phydev->drv->name, phydev->dev.bus_id, phydev->irq);
return 0;
err_out_unregister_netdev:
platform_set_drvdata(pdev, NULL);
unregister_netdev(ndev);
err_out_dma_unmap:
dma_free_coherent(&pldat->pdev->dev, pldat->dma_buff_size,
(void *) pldat->dma_buff_base_v, (dma_addr_t) pldat->dma_buff_base_p);
err_out_free_irq:
free_irq(ndev->irq, ndev);
err_out_iounmap:
iounmap(pldat->net_base);
err_out_disable_clocks:
clk_disable(pldat->clk);
clk_put(pldat->clk);
err_out_free_dev:
free_netdev(ndev);
err_exit:
printk("%s: not found (%d).\n", MODNAME, ret);
return ret;
}
总结一下lpc32xx_net_drv_probe()函数：首先根据平台设备的resource结构获得空间和中断信息，并利用这些作息初始化申请的net_device结构体，再向内核申请这些资源。再次，填充ndev的设备操作函数成员，让内核得到一些控制网络传输的方法。接着，根据芯片特点，申请了DMA缓冲区，初始化了mac。而后便是初始化以太网控制器及其与phy的数据交互接口mii,最后是一些错误处理。可以说一个probe方法完成了整个网络设备驱动的构架工作。
lpc32xx_mii_init()函数分析
static int lpc32xx_mii_init(struct netdata_local *pldat)
{
int err = -ENXIO, i;
/* Setup MII mode */
#if defined (MAC_LPC32XX_MII_SUPPORT)
__raw_writel(COMMAND_PASSRUNTFRAME, ENET_COMMAND(pldat->net_base));
#else
__raw_writel((COMMAND_PASSRUNTFRAME | COMMAND_RMII),
ENET_COMMAND(pldat->net_base));
__raw_writel(SUPP_RESET_RMII, ENET_SUPP(pldat->net_base));
#endif
pldat->mii_bus.name = "LPC32XX_mii_bus";
pldat->mii_bus.read = &lpc32xx_mdio_read;
pldat->mii_bus.write = &lpc32xx_mdio_write;
pldat->mii_bus.reset = &lpc32xx_mdio_reset;
snprintf(pldat->mii_bus.id, MII_BUS_ID_SIZE, "%x", pldat->pdev->id);
pldat->mii_bus.priv = pldat;
pldat->mii_bus.dev = &pldat->ndev->dev;
pldat->mii_bus.phy_mask = 0xFFFFFFF0;
/*在plat的结构中,mii_bus是一种PHY设备挂接的总线.该总线介于mac于phy之间，以上是它的初始化。该总线提供了read,write,reset方法，有点像字符设备中fop提供的方法*/
if (pldat->ncfg)
{
pldat->mii_bus.phy_mask = pldat->ncfg->phy_mask;
}
pldat->mii_bus.irq = kmalloc(sizeof(int) * PHY_MAX_ADDR, GFP_KERNEL);
if (!pldat->mii_bus.irq) {
err = -ENOMEM;
goto err_out;
}
for (i = 0; i < PHY_MAX_ADDR; i++)
{
pldat->mii_bus.irq[i] = PHY_POLL;
}
/*申请了一片断区域，并初始化。PHY_MAX_ADDR代表总线能接受的设备数量
一个设备将来对就这里申请的一个中断位置*/
platform_set_drvdata(pldat->ndev, &pldat->mii_bus);
//像这样的函数，个人以为，只为作指针引用方便
if (mdiobus_register(&pldat->mii_bus))
{
goto err_out_free_mdio_irq;
}
if (lpc32xx_mii_probe(pldat->ndev) != 0)
{
goto err_out_unregister_bus;
}
return 0;
err_out_unregister_bus:
mdiobus_unregister(&pldat->mii_bus);
err_out_free_mdio_irq:
kfree(pldat->mii_bus.irq);
err_out:
return err;
}
追踪(mdiobus_register(&pldat->mii_bus)
int mdiobus_register(struct mii_bus *bus)
{
int i;
int err = 0;
if (NULL == bus || NULL == bus->name ||
NULL == bus->read ||
NULL == bus->write)
return -EINVAL;
//检查总线是否被初始化
mutex_init(&bus->mdio_lock);
if (bus->reset)
bus->reset(bus);
for (i = 0; i < PHY_MAX_ADDR; i++) {
struct phy_device *phydev;
if (bus->phy_mask & (1 << i)) {
bus->phy_map[i] = NULL;
continue;
}
phydev = get_phy_device(bus, i);
if (IS_ERR(phydev))
return PTR_ERR(phydev);
/* There's a PHY at this address
* We need to set:
* 1) IRQ
* 2) bus_id
* 3) parent
* 4) bus
* 5) mii_bus
* And, we need to register it */
if (phydev) {
phydev->irq = bus->irq[i];
phydev->dev.parent = bus->dev;
/*pldat->mii_bus.dev = &pldat->ndev->dev; 这说明phydev的父设备是ndev,即物理层PHY设备的父设备为MAC设备*/
phydev->dev.bus = &mdio_bus_type;
snprintf(phydev->dev.bus_id, BUS_ID_SIZE, PHY_ID_FMT, bus->id, i);
phydev->bus = bus;
/* Run all of the fixups for this PHY */
phy_scan_fixups(phydev);
err = device_register(&phydev->dev);
if (err) {
printk(KERN_ERR "phy %d failed to register\n",
i);
phy_device_free(phydev);
phydev = NULL;
}
}
bus->phy_map[i] = phydev;
}
pr_info("%s: probed\n", bus->name);
return err;
}
EXPORT_SYMBOL(mdiobus_register);
/*经过以上源代码分析，可以看出mdiobus_register()函数为总线上所有设备进行了设置，并注册进了设备模型。从名子上看是总线注册，实际是总线上的设备注册。*/
追踪lpc32xx_mii_probe()
static int lpc32xx_mii_probe(struct net_device *ndev)
{
struct netdata_local *pldat = netdev_priv(ndev);
struct phy_device *phydev = NULL;
int phy_addr;
/* find the first phy */
for (phy_addr = 0; phy_addr < PHY_MAX_ADDR; phy_addr++)
{
if (pldat->mii_bus.phy_map[phy_addr])
{
phydev = pldat->mii_bus.phy_map[phy_addr];
break;
}
}
if (!phydev)
{
printk (KERN_ERR "%s: no PHY found\n", ndev->name);
return -1;
}
/* Attach to the PHY */
#if defined (MAC_LPC32XX_MII_SUPPORT)
phydev = phy_connect(ndev, phydev->dev.bus_id,
&lpc32xx_handle_link_change, 0, PHY_INTERFACE_MODE_MII);
#else
phydev = phy_connect(ndev, phydev->dev.bus_id,
&lpc32xx_handle_link_change, 0, PHY_INTERFACE_MODE_RMII);
#endif
if (IS_ERR(phydev))
{
printk(KERN_ERR "%s: Could not attach to PHY\n", ndev->name);
return PTR_ERR(phydev);
}
/* mask with MAC supported features */
phydev->supported &= PHY_BASIC_FEATURES;
phydev->advertising = phydev->supported;
pldat->link = 0;
pldat->speed = 0;
pldat->duplex = -1;
pldat->phy_dev = phydev;
return 0;
}
lpc32xx_mii_probe()完成了这样一个事情：找到第一个phy设备，然后根据内核配置，选用MII接口或RMII接口，之后再进行简单的配置。这个探测方法完成的是phy设备的探测。
总结一下：
lpc32xx_mii_init()函数完成的是mii接口的初始化，包括注册注册mii_bus总线上的设备，然后根据找到总线上第一个phy设备进行一些初始化设置。