OTG驱动分析（二）-蒲公英云

上回介绍了OTG功能的 OTG部分驱动，本片分析OTG功能的从设备部分驱动。从设备的注册过程和OTG的一样，首先注册设备。

流程是：

1 . 定义platform_device结构。
2 . 定义platform_device下的struct resource设备资源结构
3 . 定义 platform_device下的DEV设备下的平台私有数据（就是该设备私有的数据）
4 . 调用platform_device_register将platform_device结构
注册上面4个过程调用结束后，设备的信息就被注册到系统中，等待驱动的使用下面是按照上面顺序贴出代码

定义platform_device结构

static struct platform_device __maybe_unused dr_udc_device = { . name = “fsl-usb2-udc” , . id = - 1, . dev = { . release = dr_udc_release, . dma_mask = & dr_udc_dmamask, . coherent_dma_mask = 0xffffffff, } , . resource = otg_resources, . num_resources = ARRAY_SIZE( otg_resources) , } ;

我们可以看到resource和OTG的resource一样，使用的都是OTG那部分资源

定义platform_device下的struct resource设备资源结构

static struct resource otg_resources[ ] = { [ 0] = { . start = ( u32) ( USB_OTGREGS_BASE) , . end = ( u32) ( USB_OTGREGS_BASE + 0x1ff) , . flags = IORESOURCE_MEM, } , [ 1] = { . start = MXC_INT_USB_OTG, . flags = IORESOURCE_IRQ, } , } ;

定义platform_device下的DEV设备下的平台私有数据（就是该设备私有的数据）

static struct fsl_usb2_platform_data __maybe_unused dr_utmi_config = { . name = “DR” , . platform_init = usbotg_init, . platform_uninit = usbotg_uninit, . phy_mode = FSL_USB2_PHY_UTMI_WIDE, . power_budget = 500, / via RT9706 / . gpio_usb_active = gpio_usbotg_utmi_active, . gpio_usb_inactive = gpio_usbotg_utmi_inactive, . transceiver = “utmi” , . wake_up_enable = _wake_up_enable, } ; /将设备注册进系统/ static inline void dr_register_udc( void ) { PDATA- > operating_mode = DR_UDC_MODE; //在OTG功能设备注册的时候这里的模式是“FSL_USB2_DR_OTG ”，时还不知道为什么不开始就直接把模式写成这个而是后该，现在知道了因为主从和OTG都在用一个资源，所以谁用就的把模式该了。

/#define PDATA (&dr_utmi_config)PDATA指的就是上面的结构 / dr_udc_device. dev. platform_data = PDATA; if ( platform_device_register( & dr_udc_device) ) printk( KERN_ERR “usb: can’t register DR gadget/n” ) ; else printk( KERN_INFO “usb: DR gadget (%s) registered/n” , PDATA- > transceiver) ; }

上面就完成了设备的注册。

下面看看驱动和设备的链接。

static struct platform_driver udc_driver = { . remove = __exit_p( fsl_udc_remove) , / these suspend and resume are not usb suspend and resume / . suspend = fsl_udc_suspend, //切换到主设备后的处理过程 . resume = fsl_udc_resume, //切换到从设备的处理过程 . probe = fsl_udc_probe, . driver = { . name = driver_name, //就是fsl-usb2-udc，用于匹配设备的 . owner = THIS_MODULE, }, }

将驱动注册进系统，如果发现了设备就调用Probe函数，因为我们上面注册了设备所以必然调用Probe

static int init udc_init( void ) { printk( KERN_INFO “%s (%s)/n” , driver_desc, DRIVER_VERSION) ; return platform_driver_register( & udc_driver) ;//驱动注册进系统 }

发现设备后调用PROBE函数 static int init fsl_udc_probe( struct platform_device pdev) { struct resource res; struct fsl_usb2_platform_data pdata = pdev- > dev. platform_data; int ret = - ENODEV; unsigned int i; u32 dccparams, portsc; if ( strcmp ( pdev- > name, driver_name) ) { VDBG( “Wrong device/n” ) ; return - ENODEV; } /**/

static struct fsl_udc udc_controller;

全局变量定义

/*/ udc_controller = kzalloc( sizeof ( struct fsl_udc) , GFP_KERNEL) ; if ( udc_controller = = NULL ) { ERR( “malloc udc failed/n” ) ; return - ENOMEM; } udc_controller- > pdata = pdata; //私有变量赋值 # ifdef CONFIG_USB_OTG / Memory and interrupt resources will be passed from OTG / udc_controller- > transceiver = otg_get_transceiver( ) ;//在OTG功能中已经通过otg_set_transceiver 设置了transceiver结构，这里面就可以GET

    if ( ! udc_controller- > transceiver) {
        printk( KERN_ERR “Can’t find OTG driver!/n” ) ;
        ret = - ENODEV;
        goto err1a;
    }

    res = otg_get_resources( ) ; //获得资源
    if ( ! res) {
        DBG( “resource not registered!/n” ) ;
        return - ENODEV;
    }
# else
    if ( ( pdev- > dev. parent) & &
        ( to_platform_device( pdev- > dev. parent) - > resource) ) {
        pdev- > resource =
            to_platform_device( pdev- > dev. parent) - > resource;
        pdev- > num_resources =
            to_platform_device( pdev- > dev. parent) - > num_resources;
    }

    res = platform_get_resource( pdev, IORESOURCE_MEM, 0) ;
    if ( ! res) {
        ret = - ENXIO;
        goto err1a;
    }

    if ( ! request_mem_region( res- > start, resource_size( res) ,
                driver_name) ) {
        ERR( “request mem region for %s failed /n” , pdev- > name) ;
        ret = - EBUSY;
        goto err1a;
    }
# endif
/将物理地址映射为驱动可以访问的虚拟地址/
    dr_regs = ioremap( res- > start, resource_size( res) ) ;
    if ( ! dr_regs) {
        ret = - ENOMEM;
        goto err1;
    }
    pdata- > regs = ( void  ) dr_regs; //私有数据接收映射地址
    /
     do platform specific init: check the clock, grab/config pins, etc.
     /

/调用私有数据的初始化函数，关于初始化函数下面分析/
    if ( pdata- > platform_init & & pdata- > platform_init( pdev) ) {
        ret = - ENODEV;
        goto err2a;
    }

    if ( pdata- > have_sysif_regs)
        usb_sys_regs = ( struct usb_sys_interface  )
                ( ( u32) dr_regs + USB_DR_SYS_OFFSET) ;

    / Read Device Controller Capability Parameters register /
    dccparams = fsl_readl( & dr_regs- > dccparams) ;
    if ( ! ( dccparams & DCCPARAMS_DC) ) {
        ERR( “This SOC doesn’t support device role/n” ) ;
        ret = - ENODEV;
        goto err2;
    }
    / Get max device endpoints /
    / DEN is bidirectional ep number, max_ep doubles the number /
    udc_controller- > max_ep = ( dccparams & DCCPARAMS_DEN_MASK)  2;

# ifdef CONFIG_USB_OTG
    res+ + ;
    udc_controller- > irq = res- > start;
# else
    udc_controller- > irq = platform_get_irq( pdev, 0) ;
# endif
    if ( ! udc_controller- > irq) {
        ret = - ENODEV;
        goto err2;
    }
   /注册中断，该中断和OTG的中断共享一个/
    ret = request_irq( udc_controller- > irq, fsl_udc_irq, IRQF_SHARED,
            driver_name, udc_controller) ;
    if ( ret ! = 0) {
        ERR( “cannot request irq %d err %d /n” ,
                udc_controller- > irq, ret) ;
        goto err2;
    }

    / Initialize the udc structure including QH member and other member /

/对一些资源进行空间开辟等初始化操作/
    if ( struct_udc_setup( udc_controller, pdev) ) {
        ERR( “Can’t initialize udc data structure/n” ) ;
        ret = - ENOMEM;
        goto err3;
    }

    if ( ! udc_controller- > transceiver) {
        / initialize usb hw reg except for regs for EP,
         leave usbintr reg untouched /
        dr_controller_setup( udc_controller) ;
    }

    / Setup gadget structure /
    udc_controller- > gadget. ops = & fsl_gadget_ops;
    udc_controller- > gadget. is_dualspeed = 1;
    udc_controller- > gadget. ep0 = & udc_controller- > eps[ 0] . ep;
    INIT_LIST_HEAD( & udc_controller- > gadget. ep_list) ;
    udc_controller- > gadget. speed = USB_SPEED_UNKNOWN;
    udc_controller- > gadget. name = driver_name;

    / Setup gadget.dev and register with kernel /
    dev_set_name( & udc_controller- > gadget. dev, “gadget” ) ;
    udc_controller- > gadget. dev. release = fsl_udc_release;
    udc_controller- > gadget. dev. parent = & pdev- > dev;
    ret = device_register( & udc_controller- > gadget. dev) ;
    if ( ret < 0)
        goto err3;

    if ( udc_controller- > transceiver) {
        udc_controller- > gadget. is_otg = 1;
        / now didn’t support lpm in OTG mode/
        device_set_wakeup_capable( & pdev- > dev, 0) ;
    }

    / setup QH and epctrl for ep0 /
    ep0_setup( udc_controller) ;

    / setup udc->eps[] for ep0 /
    struct_ep_setup( udc_controller, 0, “ep0” , 0) ;
    / for ep0: the desc defined here;
     for other eps, gadget layer called ep_enable with defined desc
     /
    udc_controller- > eps[ 0] . desc = & fsl_ep0_desc;
    udc_controller- > eps[ 0] . ep. maxpacket = USB_MAX_CTRL_PAYLOAD;

    / setup the udc->eps[] for non-control endpoints and link
     to gadget.ep_list /
    for ( i = 1; i < ( int ) ( udc_controller- > max_ep / 2) ; i+ + ) {
        char name[ 14] ;

        sprintf ( name, “ep%dout” , i) ;
        struct_ep_setup( udc_controller, i  2, name, 1) ;
        sprintf ( name, “ep%din” , i) ;
        struct_ep_setup( udc_controller, i  2 + 1, name, 1) ;
    }

    / use dma_pool for TD management /
    udc_controller- > td_pool = dma_pool_create( “udc_td” , & pdev- > dev,
            sizeof ( struct ep_td_struct) ,
            DTD_ALIGNMENT, UDC_DMA_BOUNDARY) ;
    if ( udc_controller- > td_pool = = NULL ) {
        ret = - ENOMEM;
        goto err4;
    }
    if ( g_iram_size) {
        for ( i = 0; i < IRAM_PPH_NTD; i+ + ) {
            udc_controller- > iram_buffer[ i] =
             USB_IRAM_BASE_ADDR + i  g_iram_size;
            udc_controller- > iram_buffer_v[ i] =
             IO_ADDRESS( udc_controller- > iram_buffer[ i] ) ;
        }
    }
# ifdef POSTPONE_FREE_LAST_DTD
    last_free_td = NULL ;
# endif

    / disable all INTR /
    fsl_writel( 0, & dr_regs- > usbintr) ;

    dr_wake_up_enable( udc_controller, false ) ;
    udc_controller- > stopped = 1;

    portsc = fsl_readl( & dr_regs- > portsc1) ;
    portsc | = PORTSCX_PHY_LOW_POWER_SPD;
    fsl_writel( portsc, & dr_regs- > portsc1) ;

    if ( udc_controller- > pdata- > usb_clock_for_pm)
        udc_controller- > pdata- > usb_clock_for_pm( false ) ;

    create_proc_file( ) ;
    return 0;

err4:
    device_unregister( & udc_controller- > gadget. dev) ;
err3:
    free_irq( udc_controller- > irq, udc_controller) ;
err2:
    if ( pdata- > platform_uninit)
        pdata- > platform_uninit( pdata) ;
err2a:
    iounmap( ( u8 __iomem * ) dr_regs) ;
err1:
    if ( ! udc_controller- > transceiver)
        release_mem_region( res- > start, resource_size( res) ) ;
err1a:
    kfree( udc_controller) ;
    udc_controller = NULL ;
    return ret;
}

当设备使用主设备时 DEVICE的处理

static int udcsuspend( struct fsludc udc) { u32 mode, usbcmd; / open clock for register access */ if ( udc_controller- > pdata- > usb_clock_for_pm) udc_controller- > pdata- > usb_clock_for_pm( true ) ; mode = fsl_readl( & dr_regs- > usbmode) & USB_MODE_CTRL_MODE_MASK; usbcmd = fsl_readl( & dr_regs- > usbcmd) ; pr_debug( “%s(): mode 0x%x stopped %d/n” , __func , mode, udc- > stopped) ; / If the controller is already stopped, then this must be a PM suspend. Remember this fact, so that we will leave the controller stopped at PM resume time. / if ( udc- > stopped) { pr_debug( “gadget already stopped, leaving early/n” ) ; udc- > already_stopped = 1; goto out; } if ( mode ! = USB_MODE_CTRL_MODE_DEVICE) { pr_debug( “gadget not in device mode, leaving early/n” ) ; goto out; } udc- > stopped = 1; / if the suspend is not for switch to host in otg mode / if ( ( ! ( udc- > gadget. is_otg) ) | | ( fsl_readl( & dr_regs- > otgsc) & OTGSC_STS_USB_ID) ) { dr_wake_up_enable( udc, true ) ; dr_phy_low_power_mode( udc, true ) ; } / stop the controller */ usbcmd = fsl_readl( & dr_regs- > usbcmd) & ~ USB_CMD_RUN_STOP; fsl_writel( usbcmd, & dr_regs- > usbcmd) ; printk( KERN_INFO “USB Gadget suspended/n” ) ; out: if ( udc_controller- > pdata- > usb_clock_for_pm) udc_controller- > pdata- > usb_clock_for_pm( false ) ; return 0; }

当切换到从设备时调用

static int fsludcresume( struct platform_device * pdev) { pr_debug( “%s(): stopped %d already_stopped %d/n” , __func , udc_controller- > stopped, udc_controller- > already_stopped) ; / If the controller was stopped at suspend time, then don’t resume it now. / if ( udc_controller- > already_stopped) { udc_controller- > already_stopped = 0; pr_debug( “gadget was already stopped, leaving early/n” ) ; return 0; } / Enable DR irq reg and set controller Run / if ( udc_controller- > stopped) { dr_wake_up_enable( udc_controller, false ) ; dr_phy_low_power_mode( udc_controller, false ) ; mdelay( 1) ; dr_controller_setup( udc_controller) ; dr_controller_run( udc_controller) ; } udc_controller- > usb_state = USB_STATE_ATTACHED; udc_controller- > ep0_dir = 0; printk( KERN_INFO “USB Gadget resumed/n” ) ; return 0; }