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本文以imx6ul?SoC為例。

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涉及目錄及文件：

• dts: linux-4.14.141\arch\arm\boot\dts\imx6ul.dtsi

• controller: drivers\usb\chipidea

• phy: drivers\usb\phy

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幾點說明：

1）4.13?kernel

2）4.13內(nèi)核中全部是usb2.0的PHY驅(qū)動，沒有usb3.0的驅(qū)動。也許usb3.0的PHY都不需要初始化，直接就可以使用，如femtoPHY。

3）imx6ul的usb?controller和phy都集成在SoC中

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1. dts配置

\linux-4.14.141\arch\arm\boot\dts\imx6ul.dtsi

usbotg1: usb@02184000 {compatible = "fsl,imx6ul-usb", "fsl,imx27-usb";reg = <0x02184000 0x200>;interrupts = <GIC_SPI 43 IRQ_TYPE_LEVEL_HIGH>;clocks = <&clks IMX6UL_CLK_USBOH3>;fsl,usbphy = <&usbphy1>;fsl,usbmisc = <&usbmisc 0>;fsl,anatop = <&anatop>;ahb-burst-config = <0x0>;tx-burst-size-dword = <0x10>;rx-burst-size-dword = <0x10>;status = "disabled"; };usbphy1: usbphy@020c9000 {compatible = "fsl,imx6ul-usbphy", "fsl,imx23-usbphy";reg = <0x020c9000 0x1000>;interrupts = <GIC_SPI 44 IRQ_TYPE_LEVEL_HIGH>;clocks = <&clks IMX6UL_CLK_USBPHY1>;phy-3p0-supply = <&reg_3p0>;fsl,anatop = <&anatop>; };

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2.?usb?controller

drivers/usb/chipidea/ci_hdrc_imx.c

static const struct of_device_id ci_hdrc_imx_dt_ids[] = {{ .compatible = "fsl,imx23-usb", .data = &imx23_usb_data},{ .compatible = "fsl,imx28-usb", .data = &imx28_usb_data},......{ .compatible = "fsl,imx6ul-usb", .data = &imx6ul_usb_data},{ .compatible = "fsl,imx7d-usb", .data = &imx7d_usb_data},{ /* sentinel */ } };static struct platform_driver ci_hdrc_imx_driver = {.probe = ci_hdrc_imx_probe,.remove = ci_hdrc_imx_remove,.shutdown = ci_hdrc_imx_shutdown,.driver = {.name = "imx_usb",.of_match_table = ci_hdrc_imx_dt_ids,.pm = &ci_hdrc_imx_pm_ops,}, };

drivers/usb/chipidea/core.c

static struct platform_driver ci_hdrc_driver = {.probe = ci_hdrc_probe,.remove = ci_hdrc_remove,.driver = {.name = "ci_hdrc",.pm = &ci_pm_ops,}, };

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2.1 首先根據(jù)"fsl,imx6ul-usb"進行dts?match，執(zhí)行ci_hdrc_imx_probe。在此函數(shù)中：

1）首先獲得devm_usb_get_phy_by_phandle("fsl,usbphy") 獲得phy，"fsl,usbphy"在dts中有定義

2）然后調(diào)用ci_hdrc_add_device添加platform?device ("ci_hdrc")，下一步會match?相應的platform?driver

函數(shù)流程如下：

chipidea/ci_hdrc_imx.c: ci_hdrc_imx_probe ->?devm_usb_get_phy_by_phandle |?ci_hdrc_add_device ->?chipidea/core.c: platform_device_add("ci_hdrc")

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2.2 初始化PHY

1）上述添加platform?device ("ci_hdrc")后，會match到相應的platform?driver，然后執(zhí)行ci_hdrc_probe

2）在ci_hdrc_probe中初始化usb?phy

函數(shù)流程如下：

chipidea/core.c: ci_hdrc_probe -> ci_usb_phy_init -> phy.h: usb_phy_init -> (phy->init)

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3.? usb PHY

drivers/usb/phy/phy-mxs-usb.c

在該文件中主要實現(xiàn)PHY的相關操作函數(shù)，然后被controller調(diào)用進行初始化。

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1）根據(jù)"fsl,imx6ul-usbphy"進行dts?match，match到后執(zhí)行mxs_phy_probe

static const struct of_device_id mxs_phy_dt_ids[] = {{ .compatible = "fsl,imx6sx-usbphy", .data = &imx6sx_phy_data, },{ .compatible = "fsl,imx6sl-usbphy", .data = &imx6sl_phy_data, },{ .compatible = "fsl,imx6q-usbphy", .data = &imx6q_phy_data, },{ .compatible = "fsl,imx23-usbphy", .data = &imx23_phy_data, },{ .compatible = "fsl,vf610-usbphy", .data = &vf610_phy_data, },{ .compatible = "fsl,imx6ul-usbphy", .data = &imx6ul_phy_data, },{ /* sentinel */ } };

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2）在mxs_phy_probe中先設置phy的相關操作函數(shù)

mxs_phy->phy.io_priv = base;mxs_phy->phy.dev = &pdev->dev;mxs_phy->phy.label = DRIVER_NAME;mxs_phy->phy.init = mxs_phy_init;mxs_phy->phy.shutdown = mxs_phy_shutdown;mxs_phy->phy.set_suspend = mxs_phy_suspend;mxs_phy->phy.notify_connect = mxs_phy_on_connect;mxs_phy->phy.notify_disconnect = mxs_phy_on_disconnect;mxs_phy->phy.type = USB_PHY_TYPE_USB2;mxs_phy->phy.set_wakeup = mxs_phy_set_wakeup;

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3）最后通過usb_add_phy_dev(&mxs_phy->phy)添加usb?PHY，被host或device?controller?driver使用。

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4.?register

4.1?usb phy

1）usb?phy?register?base?address?

從上面可以得出usb?phy及地址是020c_9000，這也符合dts中的地址定義

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2）在phy-mxs-usb.c中定義的寄存器地址偏移

#define HW_USBPHY_PWD 0x00 #define HW_USBPHY_TX 0x10 #define HW_USBPHY_CTRL 0x30 #define HW_USBPHY_CTRL_SET 0x34 #define HW_USBPHY_CTRL_CLR 0x38 #define HW_USBPHY_DEBUG_SET 0x54 #define HW_USBPHY_DEBUG_CLR 0x58 #define HW_USBPHY_IP 0x90 #define HW_USBPHY_IP_SET 0x94 #define HW_USBPHY_IP_CLR 0x98

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4.2 usb?controller

1）usb?controller?register?base?address?

從上面可以得出usb?phy及地址是0218_4000，這也符合dts中的地址定義

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2）在chipidea/ci.h中定義的寄存器地址偏移

#define ID_ID 0x0 #define ID_HWGENERAL 0x4 #define ID_HWHOST 0x8 #define ID_HWDEVICE 0xc #define ID_HWTXBUF 0x10 #define ID_HWRXBUF 0x14 #define ID_SBUSCFG 0x90

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