一、phy执行的枚举状态定义

enum phy_state {
	PHY_DOWN=0, //down 如关闭网卡，ifconfig eth0 down
	PHY_STARTING, //1 
	PHY_READY, //2 phy设备注册成功
	PHY_PENDING, //3 phy芯片挂起
	PHY_UP, //4 开启网卡，ifconfig eth0 up
	PHY_AN, //5 网卡自动协商
	PHY_RUNNING, //6 网卡上已插入网线、并建立物理连接，同时会从这个状态切换到PHY_CHANGELINK
	PHY_NOLINK, //7 断网，如拔掉网线
	PHY_FORCING, //8 自动协商标识未被使能，就强制执行自动协商（读取phy寄存器、并设置通讯速率、半双工或全双工模式、等）
	PHY_CHANGELINK, //9 当连接时，会换到PHY_RUNNING，当断网时，会切到PHY_NOLINK
	PHY_HALTED, //10 在执行网卡关闭时（ifconfig eth0 down）会执行到这个状态，即phy挂起
	PHY_RESUMING //11 在执行网卡开启时（ifconfig eth0 up）会执行到这个状态，即phy恢复
};

二、emac接口驱动下的phy设备注册

nuc970_ether_probe //探测函数驱动
	nuc970_mii_setup
		mdiobus_register
			mdiobus_scan
				get_phy_device
					get_phy_id
					phy_device_create
						dev->autoneg = AUTONEG_ENABLE; //设置phy 自动协商使能
						dev->state = PHY_DOWN; //设置phy的状态 ----1-----
						INIT_DELAYED_WORK(&dev->state_queue, phy_state_machine); //初始化一个中断顶版本的延时工作队列，用来处理phy状态机
				phy_device_register //phy设备注册
					device_add //这里是通过堆栈信息打印的，详见下面的 堆栈信息
						bus_probe_device
							device_attach
								bus_for_each_drv
									__device_attach
										driver_probe_device
											phy_probe //非常重要的一个探测接口
												phydev->supported = phydrv->features; //phydrv->features = PHY_BASIC_FEATURES | SUPPORTED_Pause | SUPPORTED_Asym_Pause
												phydev->advertising = phydrv->features;
												phydev->state = PHY_READY; //设置phy的状态 ----2-----
		phy_connect(dev, dev_name(&phydev->dev), &adjust_link, PHY_INTERFACE_MODE_RMII);	
			phy_connect_direct
				phy_prepare_link
					phydev->adjust_link = handler; //handler = adjust_link
				phy_start_machine
					phydev->adjust_state = handler; //handler = NULL
					schedule_delayed_work(&phydev->state_queue, HZ); //启动上面注册的延时工作队列状态机 phy_state_machine

总结：上面已经将phy的状态设置成了 phydev->state = PHY_READY，同时完成了emac接口下的phy设备驱动注册，接下来将分析如何使用该phy设备驱动。

三、应用层执行ifconfig eth0 up时phy的设备状态

ifconfig eth0 up----->
nuc970_ether_open
	phy_start 
		//......
		switch (phydev->state) { //上面已经 phydev->state = PHY_READY
		case PHY_STARTING:
			phydev->state = PHY_PENDING;
			break;
		case PHY_READY:
			phydev->state = PHY_UP; //所以到这里， 设置phy的状态为 PHY_UP ----3-----
			break;
		case PHY_HALTED:
			phydev->state = PHY_RESUMING;
		default:
			break;
		}
		//......

总结：上面在执行 ifconfig eth0 up 后，已将phydev->state = PHY_UP

四、phy状态机phy_state_machine执行状态分析

phy_state_machine
	switch(phydev->state) { //关于该phydev->state的各执行状态详见本“第一”小节的介绍
	case PHY_DOWN: 
	case PHY_STARTING:
	case PHY_READY:
	case PHY_PENDING:
		break;
	case PHY_UP:
		needs_aneg = 1;

		phydev->link_timeout = PHY_AN_TIMEOUT;

		break;
	.....
	phy_start_aneg //启动自动协商
		phydev->drv->config_aneg(phydev); //这里将调用 genphy_config_aneg
			genphy_config_aneg
				genphy_config_advert //自动协商声明，关于其源码详见如下
	phydev->state = PHY_AN; //设置为自动协商，设置phy的状态为 PHY_AN ----4-----	
	//此时函数返回，又重新进入到上面的状态机 phy_state_machine，不过此时的状态已经变为 PHY_AN
	
	case PHY_AN: //自动协商 
		phy_read_status //读取phy的状态
			phydev->drv->read_status(phydev); //.read_status = genphy_read_status
				genphy_read_status
					genphy_update_link
						phy_read(phydev, MII_BMSR); //读取phy的状态寄存器
						if ((status & BMSR_LSTATUS) == 0)  //phy 的链路状态
							phydev->link = 0; //设置网卡的状态处于断开状态
						else
							phydev->link = 1; //设置网卡的状态处于连接状态
		if (!phydev->link) { //链路状态
			phydev->state = PHY_NOLINK; //协商失败，未建立连接，设置phy的状态为 PHY_NOLINK ----5-----
			netif_carrier_off(phydev->attached_dev);
			phydev->adjust_link(phydev->attached_dev);
			break;
		}	
		
		err = phy_aneg_done(phydev); //判断自动协商是否完成	
		/* If AN is done, we're running */
		if (err > 0) { //自动协商完成
			phydev->state = PHY_RUNNING; //协商成功，建立连接，设置phy的状态为 PHY_RUNNING ----6-----
			netif_carrier_on(phydev->attached_dev);
			phydev->adjust_link(phydev->attached_dev); //adjust_link = adjust_link 调用nuc970_ether0里面的接口函数

		} else if (0 == phydev->link_timeout--) { //自动协商未完成，将根据 link_timeout 次数继续尝试自动协商
			needs_aneg = 1;
			/* If we have the magic_aneg bit,
			 * we try again */
			if (phydev->drv->flags & PHY_HAS_MAGICANEG)
				break;
		}
		
	case PHY_RUNNING:
		/* Only register a CHANGE if we are
		 * polling */
		if (PHY_POLL == phydev->irq)
			phydev->state = PHY_CHANGELINK; //正常运行，设置phy的状态为 PHY_CHANGELINK ----7-----
		break;
		
	case PHY_CHANGELINK:
		err = phy_read_status(phydev); //再次获取 phy 链路状态

		if (err)
			break;

		if (phydev->link) {
			phydev->state = PHY_RUNNING; //协商成功，建立连接，设置phy的状态为 PHY_RUNNING ----8-----
			netif_carrier_on(phydev->attached_dev);
		} else {
			phydev->state = PHY_NOLINK; //协商失败，未建立连接，设置phy的状态为 PHY_NOLINK ----9-----
			netif_carrier_off(phydev->attached_dev);
		}

		phydev->adjust_link(phydev->attached_dev);  //adjust_link = adjust_link 调用nuc970_ether0里面的接口函数

		if (PHY_POLL != phydev->irq)
			err = phy_config_interrupt(phydev,
					PHY_INTERRUPT_ENABLED);
		break;	

emac接口驱动配置phy

int genphy_config_aneg(struct phy_device *phydev)
{
	int result;

	if (AUTONEG_ENABLE != phydev->autoneg) //在phy创建的时候，初始了ev->autoneg = AUTONEG_ENABLE; //设置phy 自动协商使能 
		return genphy_setup_forced(phydev);

	result = genphy_config_advert(phydev);

	if (result < 0) /* error */
		return result;

	if (result == 0) {
		/* Advertisement hasn't changed, but maybe aneg was never on to
		 * begin with?  Or maybe phy was isolated? */
		int ctl = phy_read(phydev, MII_BMCR); //获取模式控制寄存器，详见该链接对该寄存器的定义：https://wenku.baidu.com/view/b8704335ee06eff9aef807bd.html

		if (ctl < 0)
			return ctl;

		//不能自动协商 || 自动协商复位
		if (!(ctl & BMCR_ANENABLE) || (ctl & BMCR_ISOLATE)) //BMCR_ANENABLE: 自动协商使能 || 
			result = 1; /* do restart aneg */
	}

	/* Only restart aneg if we are advertising something different
	 * than we were before.	 */
	if (result > 0)
		result = genphy_restart_aneg(phydev); //重启自动协商

	return result;
}

获取自动协商配置

static int genphy_config_advert(struct phy_device *phydev)
{
	u32 advertise;
	int oldadv, adv;
	int err, changed = 0;

	/* Only allow advertising what
	 * this PHY supports */
	/*
		phy 设备在注册时初始化为如下：
			phydev->supported = phydrv->features; //phydrv->features = PHY_BASIC_FEATURES | SUPPORTED_Pause | SUPPORTED_Asym_Pause
			phydev->advertising = phydrv->features;
	*/ 
	phydev->advertising &= phydev->supported;
	advertise = phydev->advertising;

	/* Setup standard advertisement */
	oldadv = adv = phy_read(phydev, MII_ADVERTISE); //自动协商声明

	if (adv < 0)
		return adv;

	adv &= ~(ADVERTISE_ALL | ADVERTISE_100BASE4 | ADVERTISE_PAUSE_CAP |
		 ADVERTISE_PAUSE_ASYM);
	adv |= ethtool_adv_to_mii_adv_t(advertise);

	if (adv != oldadv) { //自动协商结果不一致就重新设置
		err = phy_write(phydev, MII_ADVERTISE, adv);

		if (err < 0)
			return err;
		changed = 1;
	}

	/* Configure gigabit if it's supported */
	if (phydev->supported & (SUPPORTED_1000baseT_Half |
				SUPPORTED_1000baseT_Full)) {
		oldadv = adv = phy_read(phydev, MII_CTRL1000);

		if (adv < 0)
			return adv;

		adv &= ~(ADVERTISE_1000FULL | ADVERTISE_1000HALF);
		adv |= ethtool_adv_to_mii_ctrl1000_t(advertise);

		if (adv != oldadv) {
			err = phy_write(phydev, MII_CTRL1000, adv);

			if (err < 0)
				return err;
			changed = 1;
		}
	}

	return changed;
}

重启自动协商

int genphy_restart_aneg(struct phy_device *phydev)
{
	int ctl;

	ctl = phy_read(phydev, MII_BMCR);

	if (ctl < 0)
		return ctl;

	ctl |= (BMCR_ANENABLE | BMCR_ANRESTART);

	/* Don't isolate the PHY if we're negotiating */
	ctl &= ~(BMCR_ISOLATE);

	ctl = phy_write(phydev, MII_BMCR, ctl); //设置自动协商

	return ctl;
}

总结：上面源码只要是完成emac接口与phy之间的自动协商、链路状态检测等

五、拓展信息

1. phy_probe匹配时的探测信息

===========================堆栈信息===========================	
Backtrace: 
[<c0012df8>] (dump_backtrace+0x0/0x10c) from [<c0012f1c>] (show_stack+0x18/0x1c)
 r7:c39c8374 r6:c39c8208 r5:c0474914 r4:c39c8200
[<c0012f04>] (show_stack+0x0/0x1c) from [<c0324ef4>] (dump_stack+0x20/0x2c)
[<c0324ed4>] (dump_stack+0x0/0x2c) from [<c022ae08>] (phy_probe+0x58/0x88)
[<c022adb0>] (phy_probe+0x0/0x88) from [<c01f69e4>] (driver_probe_device+0x9c/0x238)
 r7:c047496c r6:00000000 r5:c39c8208 r4:c047496c
[<c01f6948>] (driver_probe_device+0x0/0x238) from [<c01f6c5c>] (__device_attach+0x44/0x48)
[<c01f6c18>] (__device_attach+0x0/0x48) from [<c01f4ff8>] (bus_for_each_drv+0x68/0x94)
 r5:c3843cd8 r4:00000000
[<c01f4f90>] (bus_for_each_drv+0x0/0x94) from [<c01f6d14>] (device_attach+0x88/0xa0)
 r7:00000001 r6:c39c823c r5:c0474820 r4:c39c8208
[<c01f6c8c>] (device_attach+0x0/0xa0) from [<c01f5cc0>] (bus_probe_device+0x8c/0xb4)
 r7:00000001 r6:c39c8208 r5:c0474820 r4:c04b84f8
[<c01f5c34>] (bus_probe_device+0x0/0xb4) from [<c01f45d0>] (device_add+0x310/0x648)
 r7:00000001 r6:00000000 r5:c39c8208 r4:c04b84f8
[<c01f42c0>] (device_add+0x0/0x648) from [<c022bac8>] (phy_device_register+0x44/0x70)
[<c022ba84>] (phy_device_register+0x0/0x70) from [<c022bdd0>] (mdiobus_scan+0x2c/0x4c)
 r7:00000001 r6:00000000 r5:00000001 r4:c39c8200
[<c022bda4>] (mdiobus_scan+0x0/0x4c) from [<c022bf88>] (mdiobus_register+0xec/0x184)
 r5:00000001 r4:c39c8000
[<c022be9c>] (mdiobus_register+0x0/0x184) from [<c022d874>] (nuc970_ether_probe+0x2d8/0x4b4)
[<c022d59c>] (nuc970_ether_probe+0x0/0x4b4) from [<c01f7d08>] (platform_drv_probe+0x20/0x24)
[<c01f7ce8>] (platform_drv_probe+0x0/0x24) from [<c01f69e4>] (driver_probe_device+0x9c/0x238)
[<c01f6948>] (driver_probe_device+0x0/0x238) from [<c01f6c14>] (__driver_attach+0x94/0x98)
[<c01f6b80>] (__driver_attach+0x0/0x98) from [<c01f50a0>] (bus_for_each_dev+0x7c/0xa0)
 r7:c01f6b80 r6:c0474a58 r5:c3843e78 r4:00000000
[<c01f5024>] (bus_for_each_dev+0x0/0xa0) from [<c01f6828>] (driver_attach+0x20/0x28)
 r7:c046fc68 r6:c0474a58 r5:c0474a58 r4:c39a69c0
[<c01f6808>] (driver_attach+0x0/0x28) from [<c01f5990>] (bus_add_driver+0xec/0x240)
[<c01f58a4>] (bus_add_driver+0x0/0x240) from [<c01f6ffc>] (driver_register+0x60/0x150)
 r7:c3842000 r6:00000000 r5:c0474a58 r4:c044396c
[<c01f6f9c>] (driver_register+0x0/0x150) from [<c01f7fe8>] (platform_driver_register+0x4c/0x60)
 r7:c3842000 r6:00000000 r5:c043f414 r4:c044396c
[<c01f7f9c>] (platform_driver_register+0x0/0x60) from [<c04395b0>] (nuc970_ether_init+0x14/0x1c)
[<c043959c>] (nuc970_ether_init+0x0/0x1c) from [<c00087c4>] (do_one_initcall+0x38/0x150)
[<c000878c>] (do_one_initcall+0x0/0x150) from [<c04235d4>] (kernel_init_freeable+0x14c/0x224)
[<c0423488>] (kernel_init_freeable+0x0/0x224) from [<c0324528>] (kernel_init+0x10/0x15c)
[<c0324518>] (kernel_init+0x0/0x15c) from [<c000f850>] (ret_from_fork+0x14/0x24)
 r5:c0324518 r4:00000000
libphy: nuc970_rmii0: probed

2. phy标准寄存器的定义

/* Generic MII registers. */
//控制寄存器
#define MII_BMCR		0x00	/* Basic mode control register */
//状态寄存器
#define MII_BMSR		0x01	/* Basic mode status register  */
//PHY 标志
#define MII_PHYSID1		0x02	/* PHYS ID 1                   */
#define MII_PHYSID2		0x03	/* PHYS ID 2                   */

//4~8寄存器是用于自动协商的
#define MII_ADVERTISE		0x04	/* Advertisement control reg   自动协商声明*/
#define MII_LPA			0x05	/* Link partner ability reg    */
#define MII_EXPANSION		0x06	/* Expansion register          */

//保留
#define MII_CTRL1000		0x09	/* 1000BASE-T control          */
#define MII_STAT1000		0x0a	/* 1000BASE-T status           */
#define	MII_MMD_CTRL		0x0d	/* MMD Access Control Register */
#define	MII_MMD_DATA		0x0e	/* MMD Access Data Register */
#define MII_ESTATUS		0x0f	/* Extended Status             */

//制造商指定寄存器
#define MII_DCOUNTER		0x12	/* Disconnect counter          */
#define MII_FCSCOUNTER		0x13	/* False carrier counter       */
#define MII_NWAYTEST		0x14	/* N-way auto-neg test reg     */
#define MII_RERRCOUNTER		0x15	/* Receive error counter       */
#define MII_SREVISION		0x16	/* Silicon revision            */
#define MII_RESV1		0x17	/* Reserved...                 */
#define MII_LBRERROR		0x18	/* Lpback, rx, bypass error    */
#define MII_PHYADDR		0x19	/* PHY address                 */
#define MII_RESV2		0x1a	/* Reserved...                 */
#define MII_TPISTATUS		0x1b	/* TPI status for 10mbps       */
#define MII_NCONFIG		0x1c	/* Network interface config    */

关于phy的寄存器定义详见：https://wenku.baidu.com/view/b8704335ee06eff9aef807bd.html 第5页