lan8720 linux驱动

LAN8720是一款常用的以太网PHY芯片，它可以通过RMII或MII接口与Linux系统连接。下面是一个可能的LAN8720 Linux驱动程序的示例代码：

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/i2c.h>
#include <linux/netdevice.h>
#include <linux/ethtool.h>
#include <linux/of.h>
#include <linux/of_device.h>

/* LAN8720 PHY registers */
#define LAN8720_REG_BCR     0x00    /* Basic Control Register */
#define LAN8720_REG_BSR     0x01    /* Basic Status Register */
#define LAN8720_REG_PHYID1  0x02    /* PHY Identifier 1 */
#define LAN8720_REG_PHYID2  0x03    /* PHY Identifier 2 */
#define LAN8720_REG_ANAR    0x04    /* Auto-Negotiation Advertisement Register */
#define LAN8720_REG_ANLPAR  0x05    /* Auto-Negotiation Link Partner Ability Register */
#define LAN8720_REG_ANER    0x06    /* Auto-Negotiation Expansion Register */
#define LAN8720_REG_DSCR    0x10    /* PCS/TX Descriptor Register */
#define LAN8720_REG_DSCSR   0x11    /* PCS/TX Descriptor and Status Register */
#define LAN8720_REG_PHYCR   0x19    /* PHY Control Register */

#define LAN8720_PHY_RESET_DELAY_MS      100

struct lan8720_priv {
    struct device *dev;
    struct net_device *netdev;
    void __iomem *regs;
};

static int lan8720_mdio_read(struct mii_bus *bus, int phy_addr, int reg_addr)
{
    struct lan8720_priv *priv = bus->priv;
    void __iomem *regs = priv->regs;
    int val;

    writel(0x80000000 | (phy_addr << 23) | (reg_addr << 18), regs + LAN8720_REG_DSCR);
    while (!(readl(regs + LAN8720_REG_DSCSR) & 0x80000000));
    val = readl(regs + LAN8720_REG_DSCR) & 0xffff;
    return val;
}

static int lan8720_mdio_write(struct mii_bus *bus, int phy_addr, int reg_addr, u16 val)
{
    struct lan8720_priv *priv = bus->priv;
    void __iomem *regs = priv->regs;

    writel(0xc0000000 | (phy_addr << 23) | (reg_addr << 18) | val, regs + LAN8720_REG_DSCR);
    while (!(readl(regs + LAN8720_REG_DSCSR) & 0x80000000));
    return 0;
}

static int lan8720_phy_reset(struct lan8720_priv *priv)
{
    u16 val;

    /* Reset PHY */
    lan8720_mdio_write(priv->netdev->mdio_bus, priv->netdev->phydev->addr, LAN8720_REG_BCR, 0x8000);
    msleep(LAN8720_PHY_RESET_DELAY_MS);

    /* Wait for PHY to come out of reset */
    val = lan8720_mdio_read(priv->netdev->mdio_bus, priv->netdev->phydev->addr, LAN8720_REG_BCR);
    if (val & 0x8000)
        return -EBUSY;

    return 0;
}

static int lan8720_phy_init(struct lan8720_priv *priv)
{
    u16 val;

    /* Reset PHY */
    if (lan8720_phy_reset(priv))
        return -EBUSY;

    /* Enable auto-negotiation */
    lan8720_mdio_write(priv->netdev->mdio_bus, priv->netdev->phydev->addr, LAN8720_REG_BCR, 0x1000);

    /* Wait for auto-negotiation to complete */
    do {
        val = lan8720_mdio_read(priv->netdev->mdio_bus, priv->netdev->phydev->addr, LAN8720_REG_BSR);
    } while (!(val & 0x0020));

    /* Enable RX/TX */
    lan8720_mdio_write(priv->netdev->mdio_bus, priv->netdev->phydev->addr, LAN8720_REG_BCR, 0x2000);

    return 0;
}

static int lan8720_probe(struct platform_device *pdev)
{
    struct lan8720_priv *priv;
    struct net_device *netdev;
    struct device_node *np = pdev->dev.of_node;
    struct resource *res;
    int ret;

    /* Allocate private data */
    priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
    if (!priv)
        return -ENOMEM;

    /* Allocate netdev */
    netdev = alloc_etherdev(sizeof(*priv));
    if (!netdev)
        return -ENOMEM;

    /* Set netdev MAC address */
    of_property_read_u8_array(np, "local-mac-address", netdev->dev_addr, ETH_ALEN);

    /* Initialize netdev */
    netdev->netdev_ops = &lan8720_netdev_ops;
    netdev->ethtool_ops = &lan8720_ethtool_ops;
    netdev->needs_free_netdev = true;
    netif_napi_add(netdev, &priv->napi, lan8720_rx_napi, NAPI_POLL_WEIGHT);

    /* Allocate MDIO bus */
    netdev->phydev = mdiobus_alloc();
    if (!netdev->phydev) {
        free_netdev(netdev);
        return -ENOMEM;
    }

    /* Set MDIO bus parameters */
    netdev->phydev->bus = priv->netdev->mdio_bus;
    netdev->phydev->mdio_read = lan8720_mdio_read;
    netdev->phydev->mdio_write = lan8720_mdio_write;
    netdev->phydev->priv = priv;

    /* Initialize PHY */
    ret = lan8720_phy_init(priv);
    if (ret) {
        mdiobus_free(netdev->phydev->bus);
        free_netdev(netdev);
        return ret;
    }

    /* Set netdev device and add it to network interface */
    priv->dev = &pdev->dev;
    priv->netdev = netdev;
    platform_set_drvdata(pdev, priv);
    ret = register_netdev(netdev);
    if (ret) {
        mdiobus_free(netdev->phydev->bus);
        free_netdev(netdev);
        return ret;
    }

    return 0;
}

static int lan8720_remove(struct platform_device *pdev)
{
    struct lan8720_priv *priv = platform_get_drvdata(pdev);

    unregister_netdev(priv->netdev);
    mdiobus_free(priv->netdev->phydev->bus);
    free_netdev(priv->netdev);

    return 0;
}

static const struct of_device_id lan8720_of_match[] = {
    { .compatible = "smsc,lan8720" },
    { },
};
MODULE_DEVICE_TABLE(of, lan8720_of_match);

static struct platform_driver lan8720_driver = {
    .probe = lan8720_probe,
    .remove = lan8720_remove,
    .driver = {
        .name = "lan8720",
        .of_match_table = lan8720_of_match,
    },
};

module_platform_driver(lan8720_driver);

MODULE_AUTHOR("Your Name Here");
MODULE_DESCRIPTION("LAN8720 driver");
MODULE_LICENSE("GPL");

需要注意的是，以上示例代码只是一个框架，实际的驱动程序需要根据硬件的具体特性进行实现。另外，该驱动程序还包含了一个NAPI驱动程序，以便在高速网络环境下进行数据接收。