Linux学习第52天：Linux网络驱动实验（二）：一往（网）情深

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Linux版本号4.1.15 芯片I.MX6ULL 大叔学Linux 品人间百味思文短情长

本节笔记的目录如下：

四、I.MX6ULL网络驱动简介

1.I.MX6ULL网络外设设备树

2.I.MX6ULL网络驱动源码简析

3.fec_netdev_ops操作集

4.Linux内核PHY子系统与MDIO总线简析

五、网络驱动实验测试

1.LAN8720 PHY驱动测试

2.通用PHY驱动测试

3.DHCP功能配置

六、单网卡使用

1.只使用ENET2网卡

2.只使用ENET1网卡

四、I.MX6ULL网络驱动简介

1.I.MX6ULL网络外设设备树

①、必要属性
compatible：
reg：
interrupts
phy-mode
②、可选属性
phy-reset-gpios
phy-reset-duration：1ms
phy-supply
phy-handle
fsl,num-tx-queues:1
fsl,num-rx-queues:2
fsl,magic-packet：支持硬件魔术帧唤醒。
fsl,wakeup_irq
stop-mode
③、可选子节点
PHY 节点相关属性
interrupts
interrupt-parent：句柄
reg
compatible：ethernet-phy-ieee802.3-c22、ethernet-phy-idAAAA.BBBB
max-speed
I.MX6ULL 的两个网络外设节点，如下所示：

1 &fec1 {//第 1~10 行： ENET1 网口的节点属性
2 pinctrl-names = "default";
3 pinctrl-0 = <&pinctrl_enet1//第 3、 4 行设置 ENET1 所使用的引脚 pinctrl 节点信息
4 &pinctrl_enet1_reset>;
5 phy-mode = "rmii";//第 5 行设置网络对应的 PHY 芯片接口为 RMII，这个要根据实际的硬件来设置。
6 phy-handle = <&ethphy0>;//第 6 行设置 PHY 芯片的句柄为 ethphy0， MDIO 节点会设置 PHY 信。
7 phy-reset-gpios = <&gpio5 7 GPIO_ACTIVE_LOW>;
8 phy-reset-duration = <200>;
9 status = "okay";
10 };
11
12 &fec2 {//第 12~36 行： ENET2 网口的节点属性
13 pinctrl-names = "default";
14 pinctrl-0 = <&pinctrl_enet2
15 &pinctrl_enet2_reset>;
16 phy-mode = "rmii";
17 phy-handle = <&ethphy1>;
18 phy-reset-gpios = <&gpio5 8 GPIO_ACTIVE_LOW>;
19 phy-reset-duration = <200>;
20 status = "okay";
21
22 mdio {//mido 子节点用于描述 MIDO 总线
23 #address-cells = <1>;
24 #size-cells = <0>;
25
26 ethphy0: ethernet-phy@0 {
27 compatible = "ethernet-phy-ieee802.3-c22";
28 reg = <0>;
29 };
30
31 ethphy1: ethernet-phy@1 {
32 compatible = "ethernet-phy-ieee802.3-c22";
33 reg = <1>;
34 };
35 };
36 };

设备树中网络相关引脚的描述

1 pinctrl_enet1: enet1grp {
2 fsl,pins = <
3 MX6UL_PAD_ENET1_RX_EN__ENET1_RX_EN 0x1b0b0
4 MX6UL_PAD_ENET1_RX_ER__ENET1_RX_ER 0x1b0b0
5 MX6UL_PAD_ENET1_RX_DATA0__ENET1_RDATA00 0x1b0b0
6 MX6UL_PAD_ENET1_RX_DATA1__ENET1_RDATA01 0x1b0b0
7 MX6UL_PAD_ENET1_TX_EN__ENET1_TX_EN 0x1b0b0
8 MX6UL_PAD_ENET1_TX_DATA0__ENET1_TDATA00 0x1b0b0
9 MX6UL_PAD_ENET1_TX_DATA1__ENET1_TDATA01 0x1b0b0
10 MX6UL_PAD_ENET1_TX_CLK__ENET1_REF_CLK1 0x4001b009
11 >;
12 };
13
14 pinctrl_enet2: enet2grp {
15 fsl,pins = <
16 MX6UL_PAD_GPIO1_IO07__ENET2_MDC 0x1b0b0
17 MX6UL_PAD_GPIO1_IO06__ENET2_MDIO 0x1b0b0
18 MX6UL_PAD_ENET2_RX_EN__ENET2_RX_EN 0x1b0b0
19 MX6UL_PAD_ENET2_RX_ER__ENET2_RX_ER 0x1b0b0
20 MX6UL_PAD_ENET2_RX_DATA0__ENET2_RDATA00 0x1b0b0
21 MX6UL_PAD_ENET2_RX_DATA1__ENET2_RDATA01 0x1b0b0
22 MX6UL_PAD_ENET2_TX_EN__ENET2_TX_EN 0x1b0b0
23 MX6UL_PAD_ENET2_TX_DATA0__ENET2_TDATA00 0x1b0b0
24 MX6UL_PAD_ENET2_TX_DATA1__ENET2_TDATA01 0x1b0b0
25 MX6UL_PAD_ENET2_TX_CLK__ENET2_REF_CLK2 0x4001b009
26 >;
27 };
28
29 /*enet1 reset zuozhongkai*///之所以分两部分主 要 是 因 为 ENET1 的 复 位 引 脚 为 //GPIO5_IO07 ， 而 GPIO5_IO07 对 应 的 引 脚 就 是SNVS_TAMPER7，要放到 iomuxc_snvs 节点，
//所以就分成了两部分。
30 pinctrl_enet1_reset: enet1resetgrp {
31 fsl,pins = <
32 /* used for enet1 reset */
33 MX6ULL_PAD_SNVS_TAMPER7__GPIO5_IO07 0x10B0
34 >;
35 };
36
37 /*enet2 reset zuozhongkai*/
38 pinctrl_enet2_reset: enet2resetgrp {
39 fsl,pins = <
40 /* used for enet2 reset */
41 MX6ULL_PAD_SNVS_TAMPER8__GPIO5_IO08 0x10B0
42 >;
43 };

2.I.MX6ULL网络驱动源码简析

1）fec_probe 函数简析

外设驱动，芯片驱动

网络控制器部分驱动：

1 static const struct of_device_id fec_dt_ids[] = {
2 { .compatible = "fsl,imx25-fec", .data =
&fec_devtype[IMX25_FEC], },
3 { .compatible = "fsl,imx27-fec", .data =
&fec_devtype[IMX27_FEC], },
4 { .compatible = "fsl,imx28-fec", .data =
&fec_devtype[IMX28_FEC], },
5 { .compatible = "fsl,imx6q-fec", .data =
&fec_devtype[IMX6Q_FEC], },
6 { .compatible = "fsl,mvf600-fec", .data =
&fec_devtype[MVF600_FEC], },
7 { .compatible = "fsl,imx6sx-fec", .data =
&fec_devtype[IMX6SX_FEC], },
8 { .compatible = "fsl,imx6ul-fec", .data =//匹配表包含“fsl,imx6ul-fec”，因此设备树和驱动匹配上，当匹配成功以后第 19 行的 fec_probe 函数就会执行。
&fec_devtype[IMX6UL_FEC], },
9 { /* sentinel */ }
10 };
11
12 static struct platform_driver fec_driver = {
13 .driver = {
14 .name = DRIVER_NAME,
15 .pm = &fec_pm_ops,
16 .of_match_table = fec_dt_ids,
17 },
18 .id_table = fec_devtype,
19 .probe = fec_probe,
20 .remove = fec_drv_remove,
21 };

fec_probe 函数:

1 static int fec_probe(struct platform_device *pdev)
2 {
3 struct fec_enet_private *fep;
4 struct fec_platform_data *pdata;
5 struct net_device *ndev;
6 int i, irq, ret = 0;
7 struct resource *r;
8 const struct of_device_id *of_id;
9 static int dev_id;
10 struct device_node *np = pdev->dev.of_node, *phy_node;
11 int num_tx_qs;
12 int num_rx_qs;
13
14 fec_enet_get_queue_num(pdev, &num_tx_qs, &num_rx_qs);
15
16 /* Init network device */
17 ndev = alloc_etherdev_mqs(sizeof(struct fec_enet_private),
18 num_tx_qs, num_rx_qs);
19 if (!ndev)
20 return -ENOMEM;
21
22 SET_NETDEV_DEV(ndev, &pdev->dev);
23
24 /* setup board info structure */
25 fep = netdev_priv(ndev);
26
27 of_id = of_match_device(fec_dt_ids, &pdev->dev);
28 if (of_id)
29 pdev->id_entry = of_id->data;
30 fep->quirks = pdev->id_entry->driver_data;
31
32 fep->netdev = ndev;
33 fep->num_rx_queues = num_rx_qs;
34 fep->num_tx_queues = num_tx_qs;
35
36 #if !defined(CONFIG_M5272)
37 /* default enable pause frame auto negotiation */
38 if (fep->quirks & FEC_QUIRK_HAS_GBIT)
39 fep->pause_flag |= FEC_PAUSE_FLAG_AUTONEG;
40 #endif
41
42 /* Select default pin state */
43 pinctrl_pm_select_default_state(&pdev->dev);
44
45 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
46 fep->hwp = devm_ioremap_resource(&pdev->dev, r);
47 if (IS_ERR(fep->hwp)) {
48 ret = PTR_ERR(fep->hwp);
49 goto failed_ioremap;
50 }
51
52 fep->pdev = pdev;
53 fep->dev_id = dev_id++;
54
55 platform_set_drvdata(pdev, ndev);
56
57 fec_enet_of_parse_stop_mode(pdev);
58
59 if (of_get_property(np, "fsl,magic-packet", NULL))
60 fep->wol_flag |= FEC_WOL_HAS_MAGIC_PACKET;
61
62 phy_node = of_parse_phandle(np, "phy-handle", 0);
63 if (!phy_node && of_phy_is_fixed_link(np)) {
64 ret = of_phy_register_fixed_link(np);
65 if (ret < 0) {
66 dev_err(&pdev->dev,
67 "broken fixed-link specification\n");
68 goto failed_phy;
69 }
70 phy_node = of_node_get(np);
71 }
72 fep->phy_node = phy_node;
73
74 ret = of_get_phy_mode(pdev->dev.of_node);
75 if (ret < 0) {
76 pdata = dev_get_platdata(&pdev->dev);
77 if (pdata)
78 fep->phy_interface = pdata->phy;
79 else
80 fep->phy_interface = PHY_INTERFACE_MODE_MII;
81 } else {
82 fep->phy_interface = ret;
83 }
84
85 fep->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
86 if (IS_ERR(fep->clk_ipg)) {
87 ret = PTR_ERR(fep->clk_ipg);
88 goto failed_clk;
89 }
90
91 fep->clk_ahb = devm_clk_get(&pdev->dev, "ahb");
92 if (IS_ERR(fep->clk_ahb)) {
93 ret = PTR_ERR(fep->clk_ahb);
94 goto failed_clk;
95 }
96
97 fep->itr_clk_rate = clk_get_rate(fep->clk_ahb);
98
99 /* enet_out is optional, depends on board */
100 fep->clk_enet_out = devm_clk_get(&pdev->dev, "enet_out");
101 if (IS_ERR(fep->clk_enet_out))
102 fep->clk_enet_out = NULL;
103
104 fep->ptp_clk_on = false;
105 mutex_init(&fep->ptp_clk_mutex);
106
107 /* clk_ref is optional, depends on board */
108 fep->clk_ref = devm_clk_get(&pdev->dev, "enet_clk_ref");
109 if (IS_ERR(fep->clk_ref))
110 fep->clk_ref = NULL;
111
112 fep->bufdesc_ex = fep->quirks & FEC_QUIRK_HAS_BUFDESC_EX;
113 fep->clk_ptp = devm_clk_get(&pdev->dev, "ptp");
114 if (IS_ERR(fep->clk_ptp)) {
115 fep->clk_ptp = NULL;
116 fep->bufdesc_ex = false;
117 }
118
119 pm_runtime_enable(&pdev->dev);
120 ret = fec_enet_clk_enable(ndev, true);
121 if (ret)
122 goto failed_clk;
123
124 fep->reg_phy = devm_regulator_get(&pdev->dev, "phy");
125 if (!IS_ERR(fep->reg_phy)) {
126 ret = regulator_enable(fep->reg_phy);
127 if (ret) {
128 dev_err(&pdev->dev,
129 "Failed to enable phy regulator: %d\n", ret);
130 goto failed_regulator;
131 }
132 } else {
133 fep->reg_phy = NULL;
134 }
135
136 fec_reset_phy(pdev);
137
138 if (fep->bufdesc_ex)
139 fec_ptp_init(pdev);
140
141 ret = fec_enet_init(ndev);
142 if (ret)
143 goto failed_init;
144
145 for (i = 0; i < FEC_IRQ_NUM; i++) {
146 irq = platform_get_irq(pdev, i);
147 if (irq < 0) {
148 if (i)
149 break;
150 ret = irq;
151 goto failed_irq;
152 }
153 ret = devm_request_irq(&pdev->dev, irq, fec_enet_interrupt,
154 0, pdev->name, ndev);
155 if (ret)
156 goto failed_irq;
157
158 fep->irq[i] = irq;
159 }
160
161 ret = of_property_read_u32(np, "fsl,wakeup_irq", &irq);
162 if (!ret && irq < FEC_IRQ_NUM)
163 fep->wake_irq = fep->irq[irq];
164 else
165 fep->wake_irq = fep->irq[0];
166
167 init_completion(&fep->mdio_done);
168 ret = fec_enet_mii_init(pdev);
169 if (ret)
170 goto failed_mii_init;
171
172 /* Carrier starts down, phylib will bring it up */
173 netif_carrier_off(ndev);
174 fec_enet_clk_enable(ndev, false);
175 pinctrl_pm_select_sleep_state(&pdev->dev);
176
177 ret = register_netdev(ndev);
178 if (ret)
179 goto failed_register;
180
181 device_init_wakeup(&ndev->dev, fep->wol_flag &
182 FEC_WOL_HAS_MAGIC_PACKET);
183
184 if (fep->bufdesc_ex && fep->ptp_clock)
185 netdev_info(ndev, "registered PHC device %d\n", fep->dev_id);
186
187 fep->rx_copybreak = COPYBREAK_DEFAULT;
188 INIT_WORK(&fep->tx_timeout_work, fec_enet_timeout_work);
189 return 0;
......
206 return ret;
207 }

通过一个 MDIO 接口可以配置多个 PHY 芯片.

如果我们要更换其他的网络PHY 芯片，第一步就是要修改设备树中的 PHY 地址。

2)MDIO 总线注册

MDIO就是用来管理PHY芯片的，分为MDIO和MDC两根线。

mii_bus 结构体：

1 struct mii_bus {
2 const char *name;
3 char id[MII_BUS_ID_SIZE];
4 void *priv;
5 int (*read)(struct mii_bus *bus, int phy_id, int regnum);//读/些 PHY 芯片的操作函数
6 int (*write)(struct mii_bus *bus, int phy_id, int regnum,
u16 val);
7 int (*reset)(struct mii_bus *bus);
8 9
/*
10 * A lock to ensure that only one thing can read/write
11 * the MDIO bus at a time
12 */
13 struct mutex mdio_lock;
14
15 struct device *parent;
16 enum {
17 MDIOBUS_ALLOCATED = 1,
18 MDIOBUS_REGISTERED,
19 MDIOBUS_UNREGISTERED,
20 MDIOBUS_RELEASED,
21 } state;
22 struct device dev;
23
24 /* list of all PHYs on bus */
25 struct phy_device *phy_map[PHY_MAX_ADDR];
26
27 /* PHY addresses to be ignored when probing */
28 u32 phy_mask;
29
30 /*
31 * Pointer to an array of interrupts, each PHY's
32 * interrupt at the index matching its address
33 */
34 int *irq;
35 };

fec_probe 函数会调用 fec_enet_mii_init 函数完成 MII 接口的初始化，其中就包括初始化 mii_bus 下的 read 和 write 这两个函数。最终通过 of_mdiobus_register或者 mdiobus_register 函数将初始化以后的 mii_bus 注册到 Linux 内核， of_mdiobus_register 函数其实最终也是调用的 mdiobus_register 函数来完成 mii_bus 注册的.
of_mdiobus_register 函数有两个主要的功能，一个是通过 mdiobus_register函数向 Linux 内核注册 mdio 总线，另一个就是通过 of_mdiobus_register_phy 函数向内核注册PHY。

3)fec_drv_remove 函数简析

卸载 I.MX6ULL 网络驱动的时候 fec_drv_remove 函数就会执行，函数内容如下所示：

1 static int fec_drv_remove(struct platform_device *pdev)
2 {
3 struct net_device *ndev = platform_get_drvdata(pdev);
4 struct fec_enet_private *fep = netdev_priv(ndev);
5 6
cancel_delayed_work_sync(&fep->time_keep);
7 cancel_work_sync(&fep->tx_timeout_work);
8 unregister_netdev(ndev);
9 fec_enet_mii_remove(fep);
10 if (fep->reg_phy)
11 regulator_disable(fep->reg_phy);
12 if (fep->ptp_clock)
13 ptp_clock_unregister(fep->ptp_clock);
14 of_node_put(fep->phy_node);
15 free_netdev(ndev);
16
17 return 0;
18 }

本章的内容实在是太多了，以下内容在下次笔记中给出：