5--＞详解《switch 数据接收驱动框架、mtk7621集成交换芯片mt7530》之一

一、 MTK7621 网络通讯原理简述

本篇博文分析的是mtk7621的芯片所内嵌的交换芯片mt7530的驱动程序，MTK7621采用内部的 MDIO 接口管理MT7530 的 switch 芯片；MT7530包含多个7个 PHY 接口，其中第7个口连接到MTK7621芯片的eth0网口。MTK7621通过MDIO 进行寄存器读写配置使用，逻辑框图如下。

                                            ------------------|  CPU /mtk7621  ||   -----------  ||   | MAC/ephy   |  |___|__||_____|__|||                           RGMII/ ||  RXP/TXPMII    ||||------------------------------------------------||--------- |   Switch  MT7530                              ||        ||                                               ||        ||                                               ||        ||   |-----|   |-----|   |-----|   |-----|    |-----|      |____|_____|___|_____|___|_____|___|_____|____|_____|______|PHY1      PHY2      PHY3      PHY4      PHY/MAC

二、通过设备树看 MT7530 交换芯片

1.linux 内核源码相对路径:

OpenWrt/mtk7621-19.07/build_dir/target-mipsel_24kc_musl/linux-ramips_mt7621/linux-4.14.200

2.设备树文件相对路径:

/OpenWrt/mtk7621-19.07$ ls target/linux/ramips/dts/ |grep 7621
AP-MT7621A-V60.dts
MT7621.dts
mt7621.dtsi
U7621-06-256M-16M.dts
U7621-06-256M-64M.dts
U7621-06-512M-64M.dts
U7621-06.dtsi

3.mt7621.dtsi 文件内容
文件名称: target/linux/ramips/dts/mt7621.dtsi

 ethernet: ethernet@1e100000 {compatible = "mediatek,mt7621-eth";   # 对应的驱动程序 soc_mt7621.c 文件中reg = <0x1e100000 0x10000>;#address-cells = <1>;#size-cells = <1>;resets = <&rstctrl 6 &rstctrl 23>;reset-names = "fe", "eth";interrupt-parent = <&gic>;interrupts = <GIC_SHARED 3 IRQ_TYPE_LEVEL_HIGH>;mediatek,switch = <&gsw>;  #交换芯片 mt7530mdio-bus {#address-cells = <1>;#size-cells = <0>;phy1f: ethernet-phy@1f {  # 内部 MDIO 总线描述reg = <0x1f>;phy-mode = "rgmii";};};hnat: hnat@0 {compatible = "mediatek,mt7623-hnat";reg = <0 0x10000>;mtketh-ppd = "eth0";mtketh-lan = "eth0";mtketh-wan = "eth0";resets = <&rstctrl 0>;reset-names = "mtketh";};};gsw: gsw@1e110000 {compatible = "mediatek,mt7621-gsw";   # 对应驱动程序 gsw_mt7621.c 文件中。reg = <0x1e110000 0x8000>;interrupt-parent = <&gic>;interrupts = <GIC_SHARED 23 IRQ_TYPE_LEVEL_HIGH>;};

4.驱动文件位置
检索驱动文件: $ ls drivers/net/ethernet/mediatek/

built-in.o    gsw_mt7620.c  mdio.c         mdio_rt2880.h    mtk_debugfs.o  mtk_offload.h  soc_rt3050.c
esw_rt3050.c  gsw_mt7620.h  mdio.h         modules.builtin  mtk_eth_soc.c  mtk_offload.o  soc_rt3883.c
esw_rt3050.h  gsw_mt7621.c  mdio_mt7620.c  mt7530.c         mtk_eth_soc.h  soc_mt7620.c
ethtool.c     gsw_mt7621.o  mdio_mt7620.o  mt7530.h         mtk_eth_soc.o  soc_mt7621.c
ethtool.h     Kconfig       mdio.o         mt7530.o         mtk-eth-soc.o  soc_mt7621.o
ethtool.o     Makefile      mdio_rt2880.c  mtk_debugfs.c    mtk_offload.c  soc_rt2880.c

三、网口与交换芯片如何关联起来？网口驱动加载。

MT7621 的片上网口驱动 soc_mt7621.c 文件中，eth 驱动方法结构体定义如下：

static struct fe_soc_data mt7621_data = {.init_data = mt7621_init_data,           /*  芯片初始化  */.reset_fe = mt7621_fe_reset,.set_mac = mt7621_set_mac,.fwd_config = mt7621_fwd_config,         /* Vlan 转发配置    */.tx_dma = mt7621_tx_dma,.switch_init = mtk_gsw_init,            /*  关联 MT7530 交换芯片，初始化配置         */.switch_config = mt7621_gsw_config,     /*  配置 MT7530 芯片、并 probe MT7530 驱动 */.reg_table = mt7621_reg_table,.pdma_glo_cfg = FE_PDMA_SIZE_16DWORDS,.rx_int = RT5350_RX_DONE_INT,.tx_int = RT5350_TX_DONE_INT,.status_int = (MT7621_FE_GDM1_AF | MT7621_FE_GDM2_AF),.checksum_bit = MT7621_L4_VALID,.has_carrier = mt7620_has_carrier,      /* mdio_mt7621.c 状态检测 */.mdio_read = mt7620_mdio_read,          /* mdio 总线读取操作   */.mdio_write = mt7620_mdio_write,        /* mdio 总线写操作     */.mdio_adjust_link = mt7620_mdio_link_adjust, /* mdio_mt7621.c 连接检测 */
};
/* mtk7621-eth 驱动程序入口处 */
const struct of_device_id of_fe_match[] = {{ .compatible = "mediatek,mt7621-eth", .data = &mt7621_data },{},
};
MODULE_DEVICE_TABLE(of, of_fe_match);

mtk7621 片上的eth驱动就包含这 switch 芯片的驱动内容， mt7530 的驱动挂载是由 mt7621_gsw_config 函数触发。

由源码调用关系，mt7530操作函数主要是 vlan 和 port 的操作，如:mt7530_get_vlan_ports 函数，最终调用 mdiobus_read/mdio_write 函数实现操作内部芯片mt7530 的目的。

switch 交换芯片驱动加载

mtk7621 片上交换芯片设备名称mt7621-gsw ，驱动程序 gsw_mt7621.c 文件中。

   gsw: gsw@1e110000 {compatible = "mediatek,mt7621-gsw";   # 对应驱动程序 gsw_mt7621.c 文件中。reg = <0x1e110000 0x8000>;interrupt-parent = <&gic>;interrupts = <GIC_SHARED 23 IRQ_TYPE_LEVEL_HIGH>;};

mtk7621_gsw 驱动实现的是 gsw 设备实例与网口设备的绑定，卸载 mt7621-gsw 驱动，实际上是移除 gsw 与网口间关系。

mt7621-eth 初始化分析

mt7621 驱动支持的芯片操作函数集合

static struct fe_soc_data mt7621_data = {.init_data = mt7621_init_data,.reset_fe = mt7621_fe_reset,.set_mac = mt7621_set_mac,.fwd_config = mt7621_fwd_config,.tx_dma = mt7621_tx_dma,.switch_init = mtk_gsw_init,                /* switch 芯片初始化 */.switch_config = mt7621_gsw_config,.reg_table = mt7621_reg_table,.pdma_glo_cfg = FE_PDMA_SIZE_16DWORDS,.rx_int = RT5350_RX_DONE_INT,.tx_int = RT5350_TX_DONE_INT,.status_int = (MT7621_FE_GDM1_AF | MT7621_FE_GDM2_AF),.checksum_bit = MT7621_L4_VALID,.has_carrier = mt7620_has_carrier,.mdio_read = mt7620_mdio_read,.mdio_write = mt7620_mdio_write,.mdio_adjust_link = mt7620_mdio_link_adjust,
};

mtk_gsw_init 初始化

int mtk_gsw_init(struct fe_priv *priv)
{struct device_node *np = priv->switch_np;struct platform_device *pdev = of_find_device_by_node(np);struct mt7620_gsw *gsw;if (!pdev)return -ENODEV;if (!of_device_is_compatible(np, mediatek_gsw_match->compatible))return -EINVAL;gsw = platform_get_drvdata(pdev);/* 申请中断 */priv->soc->swpriv = gsw;if (gsw->irq) {request_irq(gsw->irq, gsw_interrupt_mt7621, 0,"gsw", priv);disable_irq(gsw->irq);}
/* mt7621-hw 硬件初始化 */mt7621_hw_init(gsw, np);if (gsw->irq)enable_irq(gsw->irq);return 0;
}

初始内容如下

static void mt7621_hw_init(struct mt7620_gsw *gsw, struct device_node *np)
{u32 i;u32 val;/* wardware reset the switch */fe_reset(RST_CTRL_MCM);mdelay(10);/* reduce RGMII2 PAD driving strength */rt_sysc_m32(3 << 4, 0, SYSC_PAD_RGMII2_MDIO);/* gpio mux - RGMII1=Normal mode */rt_sysc_m32(BIT(14), 0, SYSC_GPIO_MODE);/* set GMAC1 RGMII mode */rt_sysc_m32(3 << 12, 0, SYSC_REG_CFG1);/* enable MDIO to control MT7530 ，设置 MDIO 控制 MT7530 */rt_sysc_m32(3 << 12, 0, SYSC_GPIO_MODE);/* turn off all PHYs */for (i = 0; i <= 4; i++) {val = _mt7620_mii_read(gsw, i, 0x0);val |= BIT(11);_mt7620_mii_write(gsw, i, 0x0, val);}/* reset the switch */mt7530_mdio_w32(gsw, 0x7000, 0x3);usleep_range(10, 20);/* (GE1, Force 1000M/FD, FC OFF, MAX_RX_LENGTH 1536) */mtk_switch_w32(gsw, 0x2305e30b, GSW_REG_MAC_P0_MCR);mt7530_mdio_w32(gsw, 0x3600, 0x5e30b);/* (GE2, Link down) , 关闭 GE2 口，此接口暂时未使用 */mtk_switch_w32(gsw, 0x8000, GSW_REG_MAC_P1_MCR);/* Set switch max RX frame length to 2k */mt7530_mdio_w32(gsw, GSW_REG_GMACCR, 0x3F0B);/* Enable Port 6, P5 as GMAC5, P5 disable */val = mt7530_mdio_r32(gsw, 0x7804);val &= ~BIT(8);val |= BIT(6) | BIT(13) | BIT(16);mt7530_mdio_w32(gsw, 0x7804, val);val = rt_sysc_r32(0x10);val = (val >> 6) & 0x7;if (val >= 6) {/* 25Mhz Xtal - do nothing */} else if (val >= 3) {/* 40Mhz *//* disable MT7530 core clock */_mt7620_mii_write(gsw, 0, 13, 0x1f);_mt7620_mii_write(gsw, 0, 14, 0x410);_mt7620_mii_write(gsw, 0, 13, 0x401f);_mt7620_mii_write(gsw, 0, 14, 0x0);/* 省略部分代码 */ } else {/* 20Mhz Xtal - TODO */}/* RGMII */_mt7620_mii_write(gsw, 0, 14, 0x1);/* set MT7530 central align */
/* 省略部分代码 */ /* delay setting for 10/1000M */
/* 省略部分代码 */ /* lower Tx Driving*/
/* 省略部分代码 */ /* turn on all PHYs */for (i = 0; i <= 4; i++) {val = _mt7620_mii_read(gsw, i, 0);val &= ~BIT(11);_mt7620_mii_write(gsw, i, 0, val);}/* enable irq ，打开中断接收允许  */mt7530_mdio_w32(gsw, 0x7008, 0x1f);val = mt7530_mdio_r32(gsw, 0x7808);val |= 3 << 16;mt7530_mdio_w32(gsw, 0x7808, val);
}

本篇描述 mtk7621 芯片 eth 网口、switch交换芯片之间关系，驱动加载关系；在此 mtk7621 具备数据接收与发送功能，下一篇分享网络协议栈数据接收过程。

当开启 switch 交换口时（例如，通过 ifconfig eth0.2 up），mtk7621_ops 中的 mt7530_set_port 方法会被调用；设置端口、配置vlan 的 vid 号等操作，与mtk7621_ops各方法对应。