Linux数据报文接收发送总结7
2021/5/20 7:28:35
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2.4 网卡驱动初始化
每一个驱动程序（不仅仅只是网卡驱动）会使用 module_init 向内核注册一个初始化函数，当驱动被加载时，内核会调用这个函数。比如igb网卡驱动的代码位于drivers/net/ethernet/intel/igb/igb_main.c
//file: drivers/net/ethernet/intel/igb/igb_main.c
static struct pci_driver igb_driver = {
.name = igb_driver_name,
.id_table = igb_pci_tbl, // 根据此ID匹配，来绑定驱动
.probe = igb_probe, // 重点函数，硬件的初始化函数都在这里做
.remove = igb_remove,
......
};
staticint __init igb_init_module(void){
......
ret = pci_register_driver(&igb_driver);
return ret;
}驱动的pci_register_driver调用完成后，Linux内核就知道了该驱动的相关信息，比如igb网卡驱动的igb_driver_name和igb_probe函数地址等等。当网卡设备被识别以后，内核会调用其驱动的probe方法（igb_driver的probe方法是igb_probe）。驱动probe方法执行的目的就是让设备ready，对于igb网卡，其igb_probe位于drivers/net/ethernet/intel/igb/igb_main.c下。主要执行的操作如下：
/**
* igb_probe - Device Initialization Routine
* @pdev: PCI device information struct
* @ent: entry in igb_pci_tbl
*
* Returns 0 on success, negative on failure
*
* igb_probe initializes an adapter identified by a pci_dev structure.
* The OS initialization, configuring of the adapter private structure,
* and a hardware reset occur.
**/
// 当insmod 驱动ko 或 有pci设备枚举上来时，通过ID进行匹配和绑定驱动，即会调用此函数，。
//此过程是由pci总线来调用来。
static int igb_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
{
struct net_device *netdev;
struct igb_adapter *adapter;
struct e1000_hw *hw;
u16 eeprom_data = 0;
s32 ret_val;
static int global_quad_port_a; /* global quad port a indication */
const struct e1000_info *ei = igb_info_tbl[ent->driver_data];
int err, pci_using_dac;
u8 part_str[E1000_PBANUM_LENGTH];
/* Catch broken hardware that put the wrong VF device ID in
* the PCIe SR-IOV capability.
*/
if (pdev->is_virtfn) {
WARN(1, KERN_ERR "%s (%hx:%hx) should not be a VF!\n",
pci_name(pdev), pdev->vendor, pdev->device);
return -EINVAL;
}
err = pci_enable_device_mem(pdev);
if (err)
return err;
pci_using_dac = 0;
err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
if (!err) {
pci_using_dac = 1;
} else {
err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
if (err) {
dev_err(&pdev->dev,
"No usable DMA configuration, aborting\n");
goto err_dma;
}
}
err = pci_request_selected_regions(pdev, pci_select_bars(pdev,
IORESOURCE_MEM),
igb_driver_name);
if (err)
goto err_pci_reg;
pci_enable_pcie_error_reporting(pdev);
pci_set_master(pdev);
pci_save_state(pdev);
err = -ENOMEM;
netdev = alloc_etherdev_mq(sizeof(struct igb_adapter), //申请网络设备，此参数包括了申请priv成员的大小
IGB_MAX_TX_QUEUES);
if (!netdev)
goto err_alloc_etherdev;
SET_NETDEV_DEV(netdev, &pdev->dev);
pci_set_drvdata(pdev, netdev);
adapter = netdev_priv(netdev);
adapter->netdev = netdev;
adapter->pdev = pdev;
hw = &adapter->hw;
hw->back = adapter;
adapter->msg_enable = netif_msg_init(debug, DEFAULT_MSG_ENABLE);
err = -EIO;
adapter->io_addr = pci_iomap(pdev, 0, 0);
if (!adapter->io_addr)
goto err_ioremap;
/* hw->hw_addr can be altered, we'll use adapter->io_addr for unmap */
hw->hw_addr = adapter->io_addr;
netdev->netdev_ops = &igb_netdev_ops; // 设备ops操作函数
igb_set_ethtool_ops(netdev); // 注册ethtool操作，即ethtool_ops
netdev->watchdog_timeo = 5 * HZ;
strncpy(netdev->name, pci_name(pdev), sizeof(netdev->name) - 1);
netdev->mem_start = pci_resource_start(pdev, 0);
netdev->mem_end = pci_resource_end(pdev, 0);
/* PCI config space info */
hw->vendor_id = pdev->vendor;
hw->device_id = pdev->device;
hw->revision_id = pdev->revision;
hw->subsystem_vendor_id = pdev->subsystem_vendor;
hw->subsystem_device_id = pdev->subsystem_device;
/* Copy the default MAC, PHY and NVM function pointers */
memcpy(&hw->mac.ops, ei->mac_ops, sizeof(hw->mac.ops));
memcpy(&hw->phy.ops, ei->phy_ops, sizeof(hw->phy.ops));
memcpy(&hw->nvm.ops, ei->nvm_ops, sizeof(hw->nvm.ops));
/* Initialize skew-specific constants */
err = ei->get_invariants(hw);
if (err)
goto err_sw_init;
/* setup the private structure */
err = igb_sw_init(adapter);
if (err)
goto err_sw_init;
igb_get_bus_info_pcie(hw); //获取设备的硬件信息，从后面处理来看，这个设备特性还挺多。
hw->phy.autoneg_wait_to_complete = false;
/* Copper options */
if (hw->phy.media_type == e1000_media_type_copper) {
hw->phy.mdix = AUTO_ALL_MODES;
hw->phy.disable_polarity_correction = false;
hw->phy.ms_type = e1000_ms_hw_default;
}
if (igb_check_reset_block(hw))
dev_info(&pdev->dev,
"PHY reset is blocked due to SOL/IDER session.\n");
/* features is initialized to 0 in allocation, it might have bits
* set by igb_sw_init so we should use an or instead of an
* assignment.
*/
netdev->features |= NETIF_F_SG |
NETIF_F_IP_CSUM |
NETIF_F_IPV6_CSUM |
NETIF_F_TSO |
NETIF_F_TSO6 |
NETIF_F_RXHASH |
NETIF_F_RXCSUM |
NETIF_F_HW_VLAN_CTAG_RX |
NETIF_F_HW_VLAN_CTAG_TX;
/* copy netdev features into list of user selectable features */
netdev->hw_features |= netdev->features;
netdev->hw_features |= NETIF_F_RXALL;
/* set this bit last since it cannot be part of hw_features */
netdev->features |= NETIF_F_HW_VLAN_CTAG_FILTER;
netdev->vlan_features |= NETIF_F_TSO |
NETIF_F_TSO6 |
NETIF_F_IP_CSUM |
NETIF_F_IPV6_CSUM |
NETIF_F_SG;
netdev->priv_flags |= IFF_SUPP_NOFCS;
if (pci_using_dac) {
netdev->features |= NETIF_F_HIGHDMA;
netdev->vlan_features |= NETIF_F_HIGHDMA;
}
if (hw->mac.type >= e1000_82576) {
netdev->hw_features |= NETIF_F_SCTP_CSUM;
netdev->features |= NETIF_F_SCTP_CSUM;
}
netdev->priv_flags |= IFF_UNICAST_FLT;
adapter->en_mng_pt = igb_enable_mng_pass_thru(hw);
/* before reading the NVM, reset the controller to put the device in a
* known good starting state
*/
hw->mac.ops.reset_hw(hw);
/* make sure the NVM is good , i211/i210 parts can have special NVM
* that doesn't contain a checksum
*/
switch (hw->mac.type) {
case e1000_i210:
case e1000_i211:
if (igb_get_flash_presence_i210(hw)) {
if (hw->nvm.ops.validate(hw) < 0) {
dev_err(&pdev->dev,
"The NVM Checksum Is Not Valid\n");
err = -EIO;
goto err_eeprom;
}
}
break;
default:
if (hw->nvm.ops.validate(hw) < 0) {
dev_err(&pdev->dev, "The NVM Checksum Is Not Valid\n");
err = -EIO;
goto err_eeprom;
}
break;
}
/* copy the MAC address out of the NVM */
if (hw->mac.ops.read_mac_addr(hw))
dev_err(&pdev->dev, "NVM Read Error\n");
memcpy(netdev->dev_addr, hw->mac.addr, netdev->addr_len);
if (!is_valid_ether_addr(netdev->dev_addr)) {
dev_err(&pdev->dev, "Invalid MAC Address\n");
err = -EIO;
goto err_eeprom;
}
/* get firmware version for ethtool -i */
igb_set_fw_version(adapter);
/* configure RXPBSIZE and TXPBSIZE */
if (hw->mac.type == e1000_i210) {
wr32(E1000_RXPBS, I210_RXPBSIZE_DEFAULT);
wr32(E1000_TXPBS, I210_TXPBSIZE_DEFAULT);
}
setup_timer(&adapter->watchdog_timer, igb_watchdog,
(unsigned long) adapter);
setup_timer(&adapter->phy_info_timer, igb_update_phy_info,
(unsigned long) adapter);
//设备驱动的功能，在异常时进行恢复
INIT_WORK(&adapter->reset_task, igb_reset_task);
INIT_WORK(&adapter->watchdog_task, igb_watchdog_task);
/* Initialize link properties that are user-changeable */
adapter->fc_autoneg = true;
hw->mac.autoneg = true;
hw->phy.autoneg_advertised = 0x2f;
hw->fc.requested_mode = e1000_fc_default;
hw->fc.current_mode = e1000_fc_default;
igb_validate_mdi_setting(hw);
/* By default, support wake on port A */
if (hw->bus.func == 0)
adapter->flags |= IGB_FLAG_WOL_SUPPORTED;
/* Check the NVM for wake support on non-port A ports */
if (hw->mac.type >= e1000_82580)
hw->nvm.ops.read(hw, NVM_INIT_CONTROL3_PORT_A +
NVM_82580_LAN_FUNC_OFFSET(hw->bus.func), 1,
&eeprom_data);
else if (hw->bus.func == 1)
hw->nvm.ops.read(hw, NVM_INIT_CONTROL3_PORT_B, 1, &eeprom_data);
if (eeprom_data & IGB_EEPROM_APME)
adapter->flags |= IGB_FLAG_WOL_SUPPORTED;
/* now that we have the eeprom settings, apply the special cases where
* the eeprom may be wrong or the board simply won't support wake on
* lan on a particular port
*/
switch (pdev->device) {
case E1000_DEV_ID_82575GB_QUAD_COPPER:
adapter->flags &= ~IGB_FLAG_WOL_SUPPORTED;
break;
case E1000_DEV_ID_82575EB_FIBER_SERDES:
case E1000_DEV_ID_82576_FIBER:
case E1000_DEV_ID_82576_SERDES:
/* Wake events only supported on port A for dual fiber
* regardless of eeprom setting
*/
if (rd32(E1000_STATUS) & E1000_STATUS_FUNC_1)
adapter->flags &= ~IGB_FLAG_WOL_SUPPORTED;
break;
case E1000_DEV_ID_82576_QUAD_COPPER:
case E1000_DEV_ID_82576_QUAD_COPPER_ET2:
/* if quad port adapter, disable WoL on all but port A */
if (global_quad_port_a != 0)
adapter->flags &= ~IGB_FLAG_WOL_SUPPORTED;
else
adapter->flags |= IGB_FLAG_QUAD_PORT_A;
/* Reset for multiple quad port adapters */
if (++global_quad_port_a == 4)
global_quad_port_a = 0;
break;
default:
/* If the device can't wake, don't set software support */
if (!device_can_wakeup(&adapter->pdev->dev))
adapter->flags &= ~IGB_FLAG_WOL_SUPPORTED;
}
/* initialize the wol settings based on the eeprom settings */
if (adapter->flags & IGB_FLAG_WOL_SUPPORTED)
adapter->wol |= E1000_WUFC_MAG;
/* Some vendors want WoL disabled by default, but still supported */
if ((hw->mac.type == e1000_i350) &&
(pdev->subsystem_vendor == PCI_VENDOR_ID_HP)) {
adapter->flags |= IGB_FLAG_WOL_SUPPORTED;
adapter->wol = 0;
}
device_set_wakeup_enable(&adapter->pdev->dev,
adapter->flags & IGB_FLAG_WOL_SUPPORTED);
/* reset the hardware with the new settings */
igb_reset(adapter);
/* Init the I2C interface 还有个I2C的控制接口*/
err = igb_init_i2c(adapter);
if (err) {
dev_err(&pdev->dev, "failed to init i2c interface\n");
goto err_eeprom;
}
/* let the f/w know that the h/w is now under the control of the
* driver.
*/
igb_get_hw_control(adapter);
strcpy(netdev->name, "eth%d");
err = register_netdev(netdev); // 注册网络设备
if (err)
goto err_register;
/* carrier off reporting is important to ethtool even BEFORE open */
netif_carrier_off(netdev);
#ifdef CONFIG_IGB_DCA
if (dca_add_requester(&pdev->dev) == 0) {
adapter->flags |= IGB_FLAG_DCA_ENABLED;
dev_info(&pdev->dev, "DCA enabled\n");
igb_setup_dca(adapter);
}
#endif
#ifdef CONFIG_IGB_HWMON
/* Initialize the thermal sensor on i350 devices. */
if (hw->mac.type == e1000_i350 && hw->bus.func == 0) {
u16 ets_word;
/* Read the NVM to determine if this i350 device supports an
* external thermal sensor.
*/
hw->nvm.ops.read(hw, NVM_ETS_CFG, 1, &ets_word);
if (ets_word != 0x0000 && ets_word != 0xFFFF)
adapter->ets = true;
else
adapter->ets = false;
if (igb_sysfs_init(adapter))
dev_err(&pdev->dev,
"failed to allocate sysfs resources\n");
} else {
adapter->ets = false;
}
#endif
/* Check if Media Autosense is enabled */
adapter->ei = *ei;
if (hw->dev_spec._82575.mas_capable)
igb_init_mas(adapter);
/* do hw tstamp init after resetting */
igb_ptp_init(adapter);
dev_info(&pdev->dev, "Intel(R) Gigabit Ethernet Network Connection\n");
/* print bus type/speed/width info, not applicable to i354 */
if (hw->mac.type != e1000_i354) {
dev_info(&pdev->dev, "%s: (PCIe:%s:%s) %pM\n",
netdev->name,
((hw->bus.speed == e1000_bus_speed_2500) ? "2.5Gb/s" :
(hw->bus.speed == e1000_bus_speed_5000) ? "5.0Gb/s" :
"unknown"),
((hw->bus.width == e1000_bus_width_pcie_x4) ?
"Width x4" :
(hw->bus.width == e1000_bus_width_pcie_x2) ?
"Width x2" :
(hw->bus.width == e1000_bus_width_pcie_x1) ?
"Width x1" : "unknown"), netdev->dev_addr);
}
if ((hw->mac.type >= e1000_i210 ||
igb_get_flash_presence_i210(hw))) {
ret_val = igb_read_part_string(hw, part_str,
E1000_PBANUM_LENGTH);
} else {
ret_val = -E1000_ERR_INVM_VALUE_NOT_FOUND;
}
if (ret_val)
strcpy(part_str, "Unknown");
dev_info(&pdev->dev, "%s: PBA No: %s\n", netdev->name, part_str);
dev_info(&pdev->dev,
"Using %s interrupts. %d rx queue(s), %d tx queue(s)\n",
(adapter->flags & IGB_FLAG_HAS_MSIX) ? "MSI-X" :
(adapter->flags & IGB_FLAG_HAS_MSI) ? "MSI" : "legacy",
adapter->num_rx_queues, adapter->num_tx_queues);
if (hw->phy.media_type == e1000_media_type_copper) {
switch (hw->mac.type) {
case e1000_i350:
case e1000_i210:
case e1000_i211:
/* Enable EEE for internal copper PHY devices */
err = igb_set_eee_i350(hw, true, true);
if ((!err) &&
(!hw->dev_spec._82575.eee_disable)) {
adapter->eee_advert =
MDIO_EEE_100TX | MDIO_EEE_1000T;
adapter->flags |= IGB_FLAG_EEE;
}
break;
case e1000_i354:
if ((rd32(E1000_CTRL_EXT) &
E1000_CTRL_EXT_LINK_MODE_SGMII)) {
err = igb_set_eee_i354(hw, true, true);
if ((!err) &&
(!hw->dev_spec._82575.eee_disable)) {
adapter->eee_advert =
MDIO_EEE_100TX | MDIO_EEE_1000T;
adapter->flags |= IGB_FLAG_EEE;
}
}
break;
default:
break;
}
}
pm_runtime_put_noidle(&pdev->dev);
return 0;
err_register:
igb_release_hw_control(adapter);
memset(&adapter->i2c_adap, 0, sizeof(adapter->i2c_adap));
err_eeprom:
if (!igb_check_reset_block(hw))
igb_reset_phy(hw);
if (hw->flash_address)
iounmap(hw->flash_address);
err_sw_init:
kfree(adapter->shadow_vfta);
igb_clear_interrupt_scheme(adapter);
#ifdef CONFIG_PCI_IOV
igb_disable_sriov(pdev);
#endif
pci_iounmap(pdev, adapter->io_addr);
err_ioremap:
free_netdev(netdev);
err_alloc_etherdev:
pci_release_selected_regions(pdev,
pci_select_bars(pdev, IORESOURCE_MEM));
err_pci_reg:
err_dma:
pci_disable_device(pdev);
return err;
}
第5步中我们看到，网卡驱动实现了ethtool所需要的接口，也在这里注册完成函数地址的注册。当 ethtool 发起一个系统调用之后，内核会找到对应操作的回调函数。对于igb网卡来说，其实现函数都在drivers/net/ethernet/intel/igb/igb_ethtool.c下。相信你这次能彻底理解ethtool的工作原理了吧？这个命令之所以能查看网卡收发包统计、能修改网卡自适应模式、能调整RX 队列的数量和大小，是因为ethtool命令最终调用到了网卡驱动的相应方法，而不是ethtool本身有这个超能力。
第6步注册的igb_netdev_ops中包含的是igb_open等函数，该函数在网卡被启动的时候会被调用。
//file: drivers/net/ethernet/intel/igb/igb_main.c
staticconststruct net_device_ops igb_netdev_ops = {
.ndo_open = igb_open,
.ndo_stop = igb_close,
.ndo_start_xmit = igb_xmit_frame,
.ndo_get_stats64 = igb_get_stats64,
.ndo_set_rx_mode = igb_set_rx_mode,
.ndo_set_mac_address = igb_set_mac,
.ndo_change_mtu = igb_change_mtu,
.ndo_do_ioctl = igb_ioctl,
......第7步中，在igb_probe初始化过程中，还调用到了igb_alloc_q_vector。他注册了一个NAPI机制所必须的poll函数，对于igb网卡驱动来说，这个函数就是igb_poll,如下代码所示。
static int igb_alloc_q_vector(struct igb_adapter *adapter,
int v_count, int v_idx,
int txr_count, int txr_idx,
int rxr_count, int rxr_idx){
......
/* initialize NAPI */
netif_napi_add(adapter->netdev, &q_vector->napi,
igb_poll, 64);
}
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