wifi详解（三）
1????????WLAN驅動結構介紹
1.1??????SDIO驅動
在drivers/mmc下面是mmc卡，SD卡和SDIO卡驅動部分，其中包括host驅動，card驅動和core部分，由于網絡接口卡掛接在SDIO總線上，所以在此之前我們先看一下SDIO的驅動結構。其驅動在drivers/mmc目錄下的結構為：
?
|-- mmc
|?? |-- card
|?? |-- core
|?? |-- host
?
主要關注的目錄是core目錄，這個目錄是真個驅動的核心目錄，是媒體卡的通用代碼部分，包括core.c，host.c和sdio.c等。CORE 層完成了不同協議和規范的實現，并為HOST 層的驅動提供了接口函數，該目錄完成sdio總線的注冊操作，相應的ops操作，以及支持mmc的代碼。詳細的情況將在函數接口部分詳細討論。
Host目錄是不同平臺根據平臺的特性而編寫的host驅動。
1.2??????Boardcom無線通訊芯片
1.2.1?????? 概述
全球有線和無線通信半導體市場的領導者Broadcom（博通）公司（Nasdaq：BRCM）宣布，推出最新無線組合芯片BCM4330，該芯片可支持更多媒體形式和數據應用，且不會增大智能手機、平板電腦及其他移動設備的尺寸或縮短其電池壽命。BCM4330在單個芯片上集成了業界領先的Broadcom 802.11n Wi-Fi、藍牙和FM無線技術，與分立式半導體器件組成的解決方案相比，在成本、尺寸、功耗和性能上有顯著優勢，是移動設備的理想選擇。
BCM4330采用了新的Wi-Fi和藍牙標準，可支持新的、令人振奮的應用。例如，Broadcom BCM4330是業界第一款經過藍牙4.0標準認證的組合芯片解決方案， 集成了藍牙低功耗（BLE）標準。該標準使藍牙技術能以超低功耗運行，因此BCM4330非常適用于需要很長電池壽命的系統，如無線傳感器、醫療和健身監控設備等。BCM4330還支持Wi-Fi Direct?和藍牙高速（HS）標準，因此采用BCM4330的移動設備能直接相互通信，而不必先連接到接入點、成為傳統網絡的一部分，從而為很多無線設備之間新的應用和使用模式創造了機會。
Broadcom一直支持所有主流的操作系統（OS）平臺，如MicrosoftWindows和Windows Phone、Google Chrome、Android等等，而且不僅是BCM4330，所有藍牙、WLAN和GPS芯片組都提供這樣的支持。
1.2.2?????? 源碼
Bcm4330驅動源碼一般被廠商單獨提供，如果要在開發的LINUX系統中（當然它還支持多種平臺）使用該源碼，可以添加到linux kernel源碼樹里，也可以單獨組織存放，可以直接編譯到kernel，也可以編譯成模塊，然后再系統啟動的流程中或其他適當的實際加載到kernel中，一般建議單獨組織并編譯成模塊在需要的時候加載如kernel。
|-- src
|?? |-- bcmsdio
|?? |-- dhd
|?? |--dongle
|?? |--include
|?? |-- shared
|?? |-- wl
?
這里主要內容到bcmsdio，dhd和wl三個目錄下，bcm4330驅動的入口在dhd/sys/dhd_linux.c文件中的dhd_module()函數，設備的初始化和相關驅動注冊都從這里開始，
1.3??????詳細接口及代碼分析
1.3.1??????WIFI驅動流程分析
??? 以boardcom bcm4329芯片驅動為例，相應的函數流程圖如下：???????
???????????????????????
?
1.3.2?????? WIFI設備注冊流程
?
Platform_driver_register(wifi_device[_legacy])的調用將wifi_device[_legacy]驅動注冊到系統中，wifi_device_legacy是為了兼容老版本的驅動。
Path: wl/sys/wl_android.c
Static struct Platform_driver?wifi_device?={
???????? .probe???? =???? wifi_probe
???????? .remove?? =???? wifi_remove
???????? .suspend? =???? wifi_supend
???????? .resume?? =???? wifi_resume
???????? .driver???? =???? {
???????? .name????? =?????“bcmdhd_wlan”
}
}
?
Static struct Platform_driver?wifi_device_legacy?={
???????? .probe???? =???? wifi_probe
???????? .remove?? =???? wifi_remove
???????? .suspend? =???? wifi_supend
???????? .resume?? =???? wifi_resume
???????? .driver???? =???? {
???????? .name????? =?????“bcm4329_wlan”
}
}
上面的展示了wifi平臺設備驅動的注冊過程，那么在平臺相關的代碼區應該有wifi作為平臺設備被初始化和注冊的地方：
Path: kernel/arch/arm/mach-msm/msm_
static struct resource mahimahi_wifi_resources[] = {
??????? [0] = {
??????????????? .name?????????? = "bcm4329_wlan_irq",
??????????????? .start????????? =MSM_GPIO_TO_INT(MAHIMAHI_GPIO_WIFI_IRQ),
??????????????? .end??????????? = MSM_GPIO_TO_INT(MAHIMAHI_GPIO_WIFI_IRQ),
??????????????? .flags????????? = IORESOURCE_IRQ |IORESOURCE_IRQ_HIGHLEVEL | IORESOURCE_IRQ_SHAREABLE,
??????? },
};
?
static structwifi_platform_data mahimahi_wifi_control = {
????????.set_power????? = mahimahi_wifi_power,
??? ????.set_reset????? = mahimahi_wifi_reset,
????????.set_carddetect = mahimahi_wifi_set_carddetect,
??????? .mem_prealloc?? = mahimahi_wifi_mem_prealloc,
};
?
static struct platform_device mahimahi_wifi_device = {
????????.name?????????? = "bcm4329_wlan",
????????.id???????????? = 1,
????????.num_resources? = ARRAY_SIZE(mahimahi_wifi_resources),
????????.resource?????? = mahimahi_wifi_resources,
????????.dev??????????? = {
???????????????.platform_data = &mahimahi_wifi_control,
????????},
};
上面是對wifi_device設備的初始化，下面是對該設備的注冊：
static int __initmahimahi_wifi_init(void)
{
??????? int ret;
?
??????? if (!machine_is_mahimahi())
??????????????? return 0;
?
??????? printk("%s: start\n",__func__);
???????mahimahi_wifi_update_nvs("sd_oobonly=1\r\n", 0);
???????mahimahi_wifi_update_nvs("btc_params70=0x32\r\n", 1);
??????? mahimahi_init_wifi_mem();
????????ret = platform_device_register(&mahimahi_wifi_device);
??????? return ret;
}
?
late_initcall(mahimahi_wifi_init); ?????//表明在系統啟動的后期會自動調用加載該模塊
這樣，通過上面的初始化和注冊流程，wifi設備作為平臺設備和驅動就可以握手成功了，這里的平臺驅動只是對wifi設備的簡單管理，如對wifi設備的掛起和恢復等操作了。但是在wifi設備初始化之前是不能夠被掛起和恢復的，那么wifi設備是如何初始化的呢？
Path: wl/sys/wl_android.c
static int wifi_probe(structplatform_device *pdev)
{
????????struct wifi_platform_data *wifi_ctrl =
????????????????(structwifi_platform_data *)(pdev->dev.platform_data);
?
??????? DHD_ERROR(("## %s\n",__FUNCTION__));
????????wifi_irqres = platform_get_resource_byname(pdev,IORESOURCE_IRQ, "bcmdhd_wlan_irq");
??????? if (wifi_irqres == NULL)
??????????????? wifi_irqres =platform_get_resource_byname(pdev,
??????????????????????? IORESOURCE_IRQ,"bcm4329_wlan_irq");
????????wifi_control_data = wifi_ctrl;
?
????????wifi_set_power(1,0);?? /* Power On */
???????wifi_set_carddetect(1); /* CardDetect (0->1) */
?
??????? up(&wifi_control_sem);
??????? return 0;
}
這是wifi平臺設備驅動注冊時成功匹配wifi設備后調用的函數wifi_probe()，它的主要工作就是從wifi設備中獲取終端資源，并獲取wifi_platform_data類型結構賦予wifi_control_data變量，這一步很重要，下面就可以看出了它的重要性。然后調用wifi_set_power和wifi_set_carddetect函數給wifi芯片上電并檢測。
int wifi_set_power(int on, unsignedlong msec)
{
??????? DHD_ERROR(("%s = %d\n",__FUNCTION__, on));
??????? if (wifi_control_data &&wifi_control_data->set_power) {
????????????????wifi_control_data->set_power(on);
??????? }
??????? if (msec)
??????????????? msleep(msec);
??????? return 0;
}
Wifi_set_power函數中調用wifi_control_data->set_power(on)，wifi_control_data就是剛才說的那個重要變量，注意它是從wifi_device平臺設備的wifi_platform_data獲取的，那么看看上面的wifi_device初始化的代碼：
static struct platform_device mahimahi_wifi_device = {
??????? .name?????????? = "bcm4329_wlan",
??????? .id???????????? = 1,
??????? .num_resources? = ARRAY_SIZE(mahimahi_wifi_resources),
??????? .resource?????? = mahimahi_wifi_resources,
??????? .dev??????????? = {
??????????????? .platform_data =&mahimahi_wifi_control,
??????? },
};
?
static struct wifi_platform_datamahimahi_wifi_control= {
??????? .set_power????? =?mahimahi_wifi_power,
??????? .set_reset????? = mahimahi_wifi_reset,
??????? .set_carddetect =?mahimahi_wifi_set_carddetect,
??????? .mem_prealloc?? = mahimahi_wifi_mem_prealloc,
};
所以它實際調用的是mahimahi_wifi_power函數，該函數的定義在kernel/arch/arm /mach-msm/board-mahimahi-mmc.c之中：
int mahimahi_wifi_power(int on)
{
???????printk("%s: %d\n", __func__, on);
?
??????? if (on) {
???????????????config_gpio_table(wifi_on_gpio_table,
?????????????????? ???????????????ARRAY_SIZE(wifi_on_gpio_table));
???????????????mdelay(50);
??????? } else {
???????????????config_gpio_table(wifi_off_gpio_table,
?????????????????????????????????ARRAY_SIZE(wifi_off_gpio_table));
??????? }
?
??????? mdelay(100);
??????? gpio_set_value(MAHIMAHI_GPIO_WIFI_SHUTDOWN_N,on); /* WIFI_SHUTDOWN */
??????? mdelay(200);
?
???????mahimahi_wifi_power_state = on;
??????? return 0;
}
調用gpio_set_value操作wifi芯片，給wifi芯片上電。那么來看看wifi_set_ carddetect函數究竟干了什么：
Path：wl/sys/wl_android.c
static int wifi_set_carddetect(int on)
{
???????DHD_ERROR(("%s = %d\n", __FUNCTION__, on));
??????? if(wifi_control_data && wifi_control_data->set_carddetect) {
???????????????wifi_control_data->set_carddetect(on);
??????? }
??????? return 0;
}
同樣會調用wifi_device的mahimahi_wifi_set_carddetect函數：
Path:kernel/arch/arm/mach-msm/board-mahimahi-mmc.c
int mahimahi_wifi_set_carddetect(int val)
{
???????pr_info("%s: %d\n", __func__, val);
???????mahimahi_wifi_cd = val;
??????? if(wifi_status_cb) {
????????????????wifi_status_cb(val,wifi_status_cb_devid);
??????? } else
???????????????pr_warning("%s: Nobody to notify\n", __func__);
??????? return 0;
}
Wifi_status_cb代碼：
static int mahimahi_wifi_status_register(
??????????????????????? void (*callback)(intcard_present, void *dev_id),
??????????????????????? void *dev_id)
{
??????? if (wifi_status_cb)
??????????????? return -EAGAIN;
????????wifi_status_cb = callback;
?? ?????wifi_status_cb_devid = dev_id;
??????? return 0;
}
?
static unsigned intmahimahi_wifi_status(struct device *dev)
{
??????? return mahimahi_wifi_cd;
}
?
static structmmc_platform_data mahimahi_wifi_data = {
??????? .ocr_mask?????????????? = MMC_VDD_28_29,
??????? .built_in?????????????? = 1,
??????? .status???????????????? = mahimahi_wifi_status,
????????.register_status_notify= mahimahi_wifi_status_register,
??????? .embedded_sdio????????? = &mahimahi_wifi_emb_data,
};
由上面代碼；不難看出會有個地方調用mahimahi_wifi_status_register設置wifi_status_cb這個回調函數，可以跟蹤這個mahimahi_wifi_data結構體，來看看它被傳遞給了誰：
int msm_add_sdcc(unsigned intcontroller, struct mmc_platform_data *plat,
???????????????? unsigned int stat_irq,unsigned long stat_irq_flags);
?
int __initmahimahi_init_mmc(unsigned int sys_rev, unsigned debug_uart)
{
??????? ……
?
????????msm_add_sdcc(1, &mahimahi_wifi_data, 0, 0);
?
?????? ……
??????? if (system_rev > 0)
??????????????? msm_add_sdcc(2,&mahimahi_sdslot_data, 0, 0);
??????? else {
?? ?????????????mahimahi_sdslot_data.status =mahimahi_sdslot_status_rev0;
???????????????mahimahi_sdslot_data.register_status_notify = NULL;
???????????????set_irq_wake(MSM_GPIO_TO_INT(MAHIMAHI_GPIO_SDMC_CD_REV0_N), 1);
????????????????msm_add_sdcc(2, &mahimahi_sdslot_data,
???????? ……
}
可以跟蹤到這里Path：kernel/arch/arm/mach-msm/devices-msm7x30.c
struct platform_device msm_device_sdc1 = {
????????.name?????????? = "msm_sdcc",
????????.id???????????? = 1,
????????.num_resources? = ARRAY_SIZE(resources_sdc1),
????????.resource?????? = resources_sdc1,
????????.dev??????????? = {
???????????????.coherent_dma_mask????? =0xffffffff,
????????},
};
?
struct platform_device msm_device_sdc2 = {
????????.name?????????? = "msm_sdcc",
????????.id???????????? = 2,
????????.num_resources? = ARRAY_SIZE(resources_sdc2),
????????.resource?????? = resources_sdc2,
????????.dev??????????? = {
???????????????.coherent_dma_mask????? =0xffffffff,
????????},
};
?
struct platform_devicemsm_device_sdc3 = {
??????? .name?????????? = "msm_sdcc",
??????? .id???????????? = 3,
??????? .num_resources? = ARRAY_SIZE(resources_sdc3),
??????? .resource?????? = resources_sdc3,
??????? .dev??????????? = {
??????????????? .coherent_dma_mask????? = 0xffffffff,
??????? },
};
?
struct platform_device msm_device_sdc4= {
??????? .name?????????? = "msm_sdcc",
??????? .id???????????? = 4,
??????? .num_resources? = ARRAY_SIZE(resources_sdc4),
??????? .resource?????? = resources_sdc4,
??????? .dev??????????? = {
?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????439,2-16????? 62%
??????????????? .coherent_dma_mask????? = 0xffffffff,
??????? },
};
?
static struct platform_device *msm_sdcc_devices[] __initdata = {
??????? &msm_device_sdc1,
???? ???&msm_device_sdc2,
??????? &msm_device_sdc3,
??????? &msm_device_sdc4,
};
?
int __initmsm_add_sdcc(unsigned int controller, struct mmc_platform_data *plat,
??????????????????????? unsigned int stat_irq,unsigned long stat_irq_flags)
{
??????? ……
?
?????? ?pdev =msm_sdcc_devices[controller-1]; //因為傳過來的controller是1，所以下面注冊的是第一個平臺設備
????????pdev->dev.platform_data= plat;??//被傳遞給平臺設備的platform_data
?
??????? res =platform_get_resource_byname(pdev, IORESOURCE_IRQ, "status_irq");
??????? if (!res)
?????????????? ?return -EINVAL;
??????? else if (stat_irq) {
??????????????? res->start = res->end =stat_irq;
??????????????? res->flags &=~IORESOURCE_DISABLED;
??????????????? res->flags |=stat_irq_flags;
??????? }
?
????????return platform_device_register(pdev); //如上所述
}
那么這個平臺設備是什么呢，就是sd卡控制器，也就是前面說的host驅動所驅動的主機控制設備。
Path: drivers/mmc/host/msm_sdcc.c
static struct platform_drivermsmsdcc_driver = {
??????? .probe????????? =?msmsdcc_probe,
??????? .suspend??????? = msmsdcc_suspend,
??????? .resume???????? = msmsdcc_resume,
??????? .driver???????? = {
??????????????? .name?? =?"msm_sdcc",
??????? },
};
?
static int __initmsmsdcc_init(void)
{
????????return platform_driver_register(&msmsdcc_driver);
}
驅動成功匹配設備后，調用probe函數：
static int
msmsdcc_probe(structplatform_device *pdev)
{
......
if (stat_irqres &&!(stat_irqres->flags & IORESOURCE_DISABLED)) {
……
??????? } else if(plat->register_status_notify) {
????????????????plat->register_status_notify(msmsdcc_status_notify_cb,host);
??????? } else if (!plat->status)
......
}
msmsdcc_status_notify_cb調用msmsdcc_check_status函數：
msmsdcc_status_notify_cb(intcard_present, void *dev_id)
{
??????? struct msmsdcc_host *host = dev_id;
?
??????? printk(KERN_DEBUG "%s:card_present %d\n", mmc_hostname(host->mmc),
?????????????? card_present);
????????msmsdcc_check_status((unsigned long) host);
}
msmsdcc_check_status調用mmc_detect_change函數：
static void
msmsdcc_check_status(unsignedlong data)
{
??????? ……
??????? if (status ^ host->oldstat) {
??????????????? pr_info("%s: Slot statuschange detected (%d -> %d)\n",
?? ?????????????????????mmc_hostname(host->mmc),host->oldstat, status);
??????????????? if (status &&!host->plat->built_in)
????????????????????????mmc_detect_change(host->mmc, (5 * HZ) / 2);
??????????????? else
????????????????????????mmc_detect_change(host->mmc, 0);
??????? }
?
??????? host->oldstat = status;
?
out:
??????? if (host->timer.function)
??????????????? mod_timer(&host->timer,jiffies + HZ);
}
可以看到mmc_detect_change被調用了，這個函數觸發了一個延時工作：
void mmc_detect_change(structmmc_host *host, unsigned long delay)
{
……
?
????????mmc_schedule_delayed_work(&host->detect, delay);
}
這個時候它會在delay時間后，執行host->detect延時工作對應的函數，在host驅動注冊并匹配設備成功后執行的probe函數里，會調用mmc_alloc_host動態創建一個mmc_host：
msmsdcc_probe(structplatform_device *pdev)
{
......
/*
???????? * Setup our host structure
???????? */
?
????????mmc = mmc_alloc_host(sizeof(struct msmsdcc_host),&pdev->dev);
??????? if (!mmc) {
??????????????? ret = -ENOMEM;
????????? ??????goto out;
??????? }
......
}
mmc_alloc_host初始化工作入口：
struct mmc_host*mmc_alloc_host(int extra, struct device *dev)
{
......
INIT_DELAYED_WORK(&host->detect, mmc_rescan);
......
}
mmc_rescan是core.c中一個很重要的函數，它遵照 SDIO 卡協議的 SDIO 卡啟動過程，包括了非激活模式、卡識別模式和數據傳輸模式三種模式共九種狀態的轉換，你需要參照相關規范來理解。
void mmc_rescan(structwork_struct *work)
{
??????? struct mmc_host *host =
??????????????? container_of(work, structmmc_host, detect.work);
......
?????? ?mmc_power_up(host);
????????sdio_reset(host);
????????mmc_go_idle(host);
?
???????mmc_send_if_cond(host, host->ocr_avail);
?
??????? /*
???????? * First we search for SDIO...
???????? */
????????err = mmc_send_io_op_cond(host, 0, &ocr);
??????? if (!err) {
????????????????if (mmc_attach_sdio(host, ocr))
????????????????????? ??mmc_power_off(host);
??????????????? extend_wakelock = 1;
??????????????? goto out;
??????? }
......
}
這個mmc_attach_sdio函數很重要，它是SDIO卡的初始化的起點，主要工作包括：匹配SDIO卡的工作電壓，分配并初始化mmc_card結構，然后注冊mmc_card到系統中：
/*
?* Starting point for SDIO card init.
?*/
int mmc_attach_sdio(structmmc_host *host, u32 ocr)
{
??????? ……
?
????????mmc_attach_bus(host,&mmc_sdio_ops);? //初始化host的bus_ops
?
?????? ……
?
????????host->ocr = mmc_select_voltage(host, ocr);?//匹配SDIO卡工作電壓
?
??????? ……
?
??????? /*
???????? * Detect and init the card.
???????? */
????????err = mmc_sdio_init_card(host, host->ocr, NULL, 0);//檢測，分配初始化mmc_card
??????? if (err)
??????????????? goto err;
??????? card = host->card;
/*
???????? * If needed, disconnect card detectionpull-up resistor.
???????? */
??????? err = sdio_disable_cd(card);
??????? if (err)
??????????????? goto remove;
?
??????? /*
???????? *?Initialize (but don't add) all present functions.
???????? */
????????for (i = 0; i < funcs; i++, card->sdio_funcs++) {
#ifdef CONFIG_MMC_EMBEDDED_SDIO
????????????????if(host->embedded_sdio_data.funcs) {
???????????????????????struct sdio_func *tmp;
?
????????????????????????tmp = sdio_alloc_func(host->card);
????????????????????????if(IS_ERR(tmp))
???????????????????????????????goto remove;
???????????????????????tmp->num = (i + 1);
???????????????????????card->sdio_func[i] = tmp;
???????????????????????tmp->class = host->embedded_sdio_data.funcs[i].f_class;
???????????????????????tmp->max_blksize = host->embedded_sdio_data.funcs[i].f_maxblksize;
???????????????????????tmp->vendor = card->cis.vendor;
???????????????????????tmp->device = card->cis.device;
????????????????} else {
#endif
??????????????????????? err =sdio_init_func(host->card, i + 1);
??????????????????????? if (err)
??????????????????????????????? goto remove;
#ifdefCONFIG_MMC_EMBEDDED_SDIO
??????????????? }
#endif
??????? }
?
??????? mmc_release_host(host);
?
??????? /*
???????? * First add the card to the drivermodel...
???????? */
????????err = mmc_add_card(host->card);? ?? //添加mmc_card
??????? if (err)
??????????????? goto remove_added;
?
??????? /*
???????? * ...then the SDIO functions.
???????? */
??????? for (i = 0;i < funcs;i++) {
????????????????err =sdio_add_func(host->card->sdio_func[i]);??????????????//將sdio_func加入系統
?????????? ?????if (err)
?????????????????????? goto remove_added;
??????? }
?
??????? return 0;
......
}
這樣，SDIO卡已經初始化成功并添加到了驅動中。上面說的過程是在SDIO設備注冊時的調用流程，mmc_rescan是整個流程主體部分，由它來完成SDIO設備的初始化和添加。其實上面的流程只是創建，初始化，添加SDIO設備的一條線，還有另外的兩條線也會調用mmc_rescan函數進行SDIO設備的上述操作：
（1）??? 加載SDIO host驅動模塊
（2）??? SDIO設備中斷
1.3.2.1????????加載SDIO host驅動模塊
Host作為平臺設備被注冊，前面也有列出相應源碼：
static struct platform_drivermsmsdcc_driver = {
??????? .probe????????? =?msmsdcc_probe,
??????? .suspend??????? = msmsdcc_suspend,
??????? .resume???????? = msmsdcc_resume,
??????? .driver?????? ??= {
??????????????? .name?? = "msm_sdcc",
??????? },
};
?
static int __initmsmsdcc_init(void)
{
????????returnplatform_driver_register(&msmsdcc_driver);
}
?
Probe函數會調用mmc_alloc_host函數（代碼前面已經貼出）來創建mmc_host結構變量，進行必要的初始化之后，調用mmc_add_host函數將它添加到驅動里面：
int mmc_add_host(structmmc_host *host)
{
??????? ……
?
??????? err =device_add(&host->class_dev);
??????? if (err)
??????????????? return err;
????????mmc_start_host(host);
??????? if (!(host->pm_flags &MMC_PM_IGNORE_PM_NOTIFY))
??????????????? register_pm_notifier(&host->pm_notify);
?
??????? return 0;
}
???????Mmc_start_host定義如下：
void mmc_start_host(structmmc_host *host)
{
??????mmc_power_off(host);
?????? mmc_detect_change(host, 0);
}
mmc_power_off中對?ios進行了設置，然后調用?mmc_set_ios(host);
host->ios.power_mode = MMC_POWER_OFF;
?????? host->ios.bus_width = MMC_BUS_WIDTH_1;
?????? host->ios.timing =MMC_TIMING_LEGACY;
?????? mmc_set_ios(host);
mmc_set_ios(host) 中的關鍵語句 host->ops->set_ios(host, ios)，實際上在host驅動的probe函數中就已經對host->ops進行了初始化：
……
/*
???????? * Setup MMC host structure
???????? */
????????mmc->ops = &msmsdcc_ops;
……
?
static const structmmc_host_ops msmsdcc_ops = {
??????? .request??????? = msmsdcc_request,
??????? .set_ios??????? =msmsdcc_set_ios,
??????? .enable_sdio_irq =msmsdcc_enable_sdio_irq,
};
?
所以實際上調用的是msmsdcc_set_ios，關于這個函數就不介紹了，可以參考源碼，再看 mmc_detect_change(host, 0)，最后一句是：
??????mmc_schedule_delayed_work(&host->detect,delay);
實際上就是調用我們前面說的延時函數 mmc_rescan，后面的流程是一樣的。
1.3.2.2????????SDIO設備中斷
SDIO設備通過SDIO總線與host相連，SDIO總線的DAT[1]即pin8可以作為中斷線使用，當SDIO設備向host產生中斷時，host會對終端做出相應的動作，在host驅動的probe函數中申請并注冊相應的中斷函數：
static int
msmsdcc_probe(structplatform_device *pdev)
{
......
? cmd_irqres = platform_get_resource_byname(pdev, IORESOURCE_IRQ,
?????????????????????????????????????????????????"cmd_irq");
??????? pio_irqres =platform_get_resource_byname(pdev, IORESOURCE_IRQ,
?????????????????????????????????????????????????"pio_irq");
????????stat_irqres =platform_get_resource_byname(pdev, IORESOURCE_IRQ,
??????????????????????????????????????????????????"status_irq");
......
? if (stat_irqres && !(stat_irqres->flags &IORESOURCE_DISABLED)) {
??????????????? unsigned long irqflags =IRQF_SHARED |
??????????????????????? (stat_irqres->flags& IRQF_TRIGGER_MASK);
?
????????????????host->stat_irq = stat_irqres->start;
????????????????ret = request_irq(host->stat_irq,
??????????????????????????????????msmsdcc_platform_status_irq,
?????????????????????????????????irqflags,
?????????????????????????????????DRIVER_NAME " (slot)",
?????????????????????????????????host);
??????????????? if (ret) {
??????????????????????? pr_err("%s: Unableto get slot IRQ %d (%d)\n",
??????????????????????????????mmc_hostname(mmc), host->stat_irq, ret);
??????????????????????? goto clk_disable;
??????????????? }
??????? }
......
}
當產生相應的中斷時調用msmsdcc_platform_status_irq中斷處理函數，這個函數的處理流程：
msmsdcc_platform_status_irq—>
msmsdcc_check_statusà
mmc_detect_changeà
mmc_rescanà
那么，這里為何調用mmc_rescan呢？因為前面說過mmc_rescanrescan函數主要用于SDIO設備的初始化，如果SDIO設備產生中斷不應該是已經初始化可以使用了嗎？其實mmc_rescan還有其它的工作，從函數名就能看出來它還有再掃描檢測功能，即如果設備產生了中斷，mmc_rescan函數一開始就會再次檢測所有掛接在該host上的所有SDIO設備，確認是否存在，如果不存在就做相應的釋放工作，以確保數據的一致性。如果檢測到了新的設備那么它就會創建一個新的mmc_card，初始化并添加該設備。
中斷引發的調用mmc_rescan動作的意義：實現了SDIO設備的熱插拔功能。
1.3.3?????? WIFI驅動流程（二）
?
? 此調用流程由dhd_bus_register發起，通過sdio_register_driver注冊一個sdio設備驅動，然后通過dhdsdio_probe初始化并注冊一個網絡設備，網絡設備的注冊標志著wifi驅動已經成功加載，關于網絡設備的創建，初始化和注冊后面會有詳細介紹，先來理一下上面的調用流程，：
?
dhd_mudule_init—>???????????? //path:dhd/sys/dhd_linux.c
Dhd_bus_registerà??????? // dhd/sys/dhd_sdio.c
Bcmsdh_registerà???????? // bcmsdio/sys/bcmsdh_linux.c
Sdio_function_inità????????????? // bcmsdio/sys/bcmsdh_sdmmc_linux.c
Sdio_register_driverà? // bcmsdio/sys/bcmsdh_sdmmc_linux.c
Bcmsdh_sdmmc_probeà//bcmsdio/sys/bcmsdh_sdmmc_linux.c
Bcmsdh_probeà//bcmsdio/sys/bcmsdh_linux.c
Bcmsdio_probeà //dhd/sys/dhd_sdio.c
這里注意上面兩個紅色標記的函數，sdio_register_driver注冊了一個sdio設備，在匹配成功后調用bcmsdh_sdmmc_probe函數，這個函數會調用bcmsdh_probe。這里有一點要注意：瀏覽bcmsdh_linux.c文件可以看出，在bcmsdh_register函數中，當定義了BCMLXSDMMC宏時，會調用sdio_function_init函數，否則調用driver_register函數：
int
bcmsdh_register(bcmsdh_driver_t*driver)
{
??????? int error = 0;
?
????????drvinfo = *driver; //注意這里，后面會介紹到它的用處
?
#if defined(BCMPLATFORM_BUS)
#if defined(BCMLXSDMMC)
???????SDLX_MSG(("Linux Kernel SDIO/MMC Driver\n"));
????????error =sdio_function_init();
#else
???????SDLX_MSG(("Intel PXA270 SDIO Driver\n"));
????????error =driver_register(&bcmsdh_driver);
#endif /* defined(BCMLXSDMMC) */
??????? return error;
#endif /*defined(BCMPLATFORM_BUS) */
?
#if !defined(BCMPLATFORM_BUS)&& !defined(BCMLXSDMMC)
#if (LINUX_VERSION_CODE <KERNEL_VERSION(2, 6, 0))
??????? if (!(error =pci_module_init(&bcmsdh_pci_driver)))
?? ?????????????return 0;
#else
??????? if (!(error =pci_register_driver(&bcmsdh_pci_driver)))
??????????????? return 0;
#endif
?
??????? SDLX_MSG(("%s: pci_module_initfailed 0x%x\n", __FUNCTION__, error));
#endif /* BCMPLATFORM_BUS */
?
??????? return error;
}
上面的流程中有sdio_function_init的調用出現，所以這里實際上BCMLXSDMMC宏被定義了，bcmsdh_probe函數只是作為一個普通函數被調用，如果不定義該宏，那么bcmsdh_probe函數會被作為驅動匹配設備后第一個調用的函數而被自動調用。
再看看dhdsdio_probe函數調用的玄機，從上面的bcmsdh_register函數可以看出它的參數被傳遞給了drvinfo，看看bcmsdh_register的調用地方：
static bcmsdh_driver_t dhd_sdio = {
????????dhdsdio_probe,
????????dhdsdio_disconnect
};
?
int
dhd_bus_register(void)
{
??????? DHD_TRACE(("%s: Enter\n",__FUNCTION__));
?
??????? return?bcmsdh_register(&dhd_sdio);
}
上面傳遞的參數是dhd_sdio結構變量，被用兩個函數初始化了，那么哪一個是attach呢？需要找到定義bcmsdh_driver_t結構定義的地方：
Path：src/include/bcmsdh.h
/* callback functions */
typedef struct {
??????? /* attach to device */
????????void *(*attach)(uint16 vend_id, uint16 dev_id, uint16 bus,uint16 slot,
???????????????????????uint16 func, uint bustype, void * regsva, osl_t * osh,
???????????????????????void * param);
??????? /* detach from device */
??????? void (*detach)(void *ch);
} bcmsdh_driver_t;
沒錯，就是第一個dhdsdio_probe函數，再來看看什么地方調用了這個attach函數：
Path:bcmsdio/sys/bcmsdh_linux.c
?
#ifndef BCMLXSDMMC
static
#endif /* BCMLXSDMMC */
int bcmsdh_probe(struct device*dev)
{
......
if (!(sdhc->ch =?drvinfo.attach((vendevid>> 16),
????????????????????????????????????????(vendevid & 0xFFFF), 0, 0, 0, 0,
??????????????????????????????????????? (void*)regs, NULL, sdh))) {
???????????? ???SDLX_MSG(("%s: device attachfailed\n", __FUNCTION__));
??????????????? goto err;
??????? }
?
??????? return 0;
......
}
紅色部分的函數調用是drvinfo.attach，就是上面傳遞過來的dhdsdio_probe函數了，仔細閱讀你會發現上面那個bcmsdh_driver_t結構體定義的地方有個說明，即把該結構的成員函數當做callback函數來使用，這就是它的用意所在。
1.3.4?????? 網絡設備注冊流程
?
上面是網絡設備注冊流程，在dhdsdio_probe函數中先后對dhd_attach和dhd_net_attach兩個函數調用，dhd_attach主要用于創建和初始化dhd_info_t和net_device兩個結構變量，然后調用dhd_add_if將創建的net_device變量添加到dhd_info_t變量的iflist列表中（支持多接口）。
Dhd_attach的流程如下：
dhd_pub_t *
dhd_attach(osl_t *osh, structdhd_bus *bus, uint bus_hdrlen)
{
??????? dhd_info_t *dhd = NULL;
??????? struct net_device *net = NULL;
?
......
??????? /* Allocate etherdev, including spacefor private structure */
????????if (!(net = alloc_etherdev(sizeof(dhd)))) {???//網絡設備的創建
??????????????? DHD_ERROR(("%s: OOM -alloc_etherdev\n", __FUNCTION__));
??????????????? goto fail;
??????? }
??????? dhd_state |=DHD_ATTACH_STATE_NET_ALLOC;
?
?
??????? /* Allocate primary dhd_info */
????????if (!(dhd = MALLOC(osh, sizeof(dhd_info_t)))) { //dhd的創建
??????????????? DHD_ERROR(("%s: OOM -alloc dhd_info\n", __FUNCTION__));
??????????????? goto fail;
??????? }
......
/* Set network interface name if it was provided as moduleparameter */
??????? if (iface_name[0]) {
??????????????? int len;
??????????????? char ch;
??????????????? strncpy(net->name,iface_name, IFNAMSIZ);
??????????????? net->name[IFNAMSIZ - 1] = 0;
??????????????? len = strlen(net->name);
??????????????? ch = net->name[len - 1];
??????????????? if ((ch > '9' || ch <'0') && (len < IFNAMSIZ - 2))
??????????????????????? strcat(net->name,"%d");
??????? }
?
????????if (dhd_add_if(dhd, 0, (void *)net, net->name, NULL, 0, 0)== DHD_BAD_IF)???//將前面創建的net添加到iflist列表中
??????????????? goto fail;
??????? dhd_state |= DHD_ATTACH_STATE_ADD_IF;
......
Memcpy(netdev_priv(net), &dhd, sizeof(dhd));?//關聯dhd和net
?
//dhd的初始化工作
}
Dhd_add_if的添加網絡接口流程：
int
dhd_add_if(dhd_info_t *dhd, int ifidx, void *handle, char *name,
????????uint8 *mac_addr,uint32 flags, uint8 bssidx)
{
??????? dhd_if_t *ifp;
?
??????? DHD_TRACE(("%s: idx %d,handle->%p\n", __FUNCTION__, ifidx, handle));
?
??????? ASSERT(dhd && (ifidx <DHD_MAX_IFS));
?
????????ifp =dhd->iflist[ifidx];
??????? if (ifp != NULL) {
??????????????? if (ifp->net != NULL) {
???????????????????????netif_stop_queue(ifp->net);
???????????????????????unregister_netdev(ifp->net);
????????????????????????free_netdev(ifp->net);?? //如果已經存在，釋放net成員
??????????????? }
??????? } else
????????????????if ((ifp = MALLOC(dhd->pub.osh,sizeof(dhd_if_t))) == NULL) {
???????????????????????DHD_ERROR(("%s: OOM - dhd_if_t\n", __FUNCTION__)); ???? //否則，創建一個dhd_if_t結構變量
??????????????????????? return -ENOMEM;
??????????????? }
?
??????? memset(ifp, 0, sizeof(dhd_if_t));
????????ifp->info = dhd;??????//進行系列初始化，添加工作
???????dhd->iflist[ifidx] = ifp;
???????strncpy(ifp->name, name, IFNAMSIZ);
??????? ifp->name[IFNAMSIZ] = '\0';
??????? if (mac_addr != NULL)
????????????????memcpy(&ifp->mac_addr, mac_addr,ETHER_ADDR_LEN);
?
??????? if (handle == NULL) {
??????????????? ifp->state = DHD_IF_ADD;
??????????????? ifp->idx = ifidx;
??????????????? ifp->bssidx = bssidx;
???????????????ASSERT(&dhd->thr_sysioc_ctl.thr_pid >= 0);
???????????????up(&dhd->thr_sysioc_ctl.sema);
??????? } else
????????????????ifp->net = (struct net_device *)handle;?????????????//handle即一個net_device變量
?
??????? return 0;
}
這樣，一個net_device網路設備就被添加到了接口管理列表中了，但是這是網路設備還沒有完成初始化和注冊工作，bcmsdio_probe函數隨后對dhd_net_attach的調用完成了這個操作：
int
dhd_net_attach(dhd_pub_t*dhdp, int ifidx)
{
??????? dhd_info_t *dhd = (dhd_info_t*)dhdp->info;
??????? struct net_device *net = NULL;
??????? int err = 0;
??????? uint8 temp_addr[ETHER_ADDR_LEN] = {0x00, 0x90, 0x4c, 0x11, 0x22, 0x33 };
?
??????? DHD_TRACE(("%s: ifidx %d\n",__FUNCTION__, ifidx));
?
??????? ASSERT(dhd &&dhd->iflist[ifidx]);
?
????????net = dhd->iflist[ifidx]->net;??????????????//首先從剛才添加的接口列表中取出net，然后進行下面的系列初始化工作
??????? ASSERT(net);
//根據內核版本信息，選擇對net成員函數的初始化方式，假設是2.6.30的版本
#if (LINUX_VERSION_CODE <KERNEL_VERSION(2, 6, 31))
??????? ASSERT(!net->open);
????????net->get_stats = dhd_get_stats;
????????net->do_ioctl =dhd_ioctl_entry;
???????net->hard_start_xmit = dhd_start_xmit;
???????net->set_mac_address = dhd_set_mac_address;
???????net->set_multicast_list = dhd_set_multicast_list;
????????net->open =net->stop = NULL;
#else
??????? ASSERT(!net->netdev_ops);
??????? net->netdev_ops = &dhd_ops_virt;
#endif
?
??????? /* Ok, link into the network layer...*/
??????? if (ifidx == 0) {
??????????????? /*
???????????????? * device functions for theprimary interface only
???????????????? */
#if (LINUX_VERSION_CODE <KERNEL_VERSION(2, 6, 31))
????????????????net->open = dhd_open;
???????????????net->stop = dhd_stop;
#else
??????????? ????net->netdev_ops = &dhd_ops_pri;
#endif
??????? } else {
??????????????? /*
???????????????? * We have to use the primaryMAC for virtual interfaces
??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????3417,1-8????? 66%
???????????????? */
??????????????? memcpy(temp_addr,dhd->iflist[ifidx]->mac_addr, ETHER_ADDR_LEN);
??????????????? /*
???????????????? * Android sets the locallyadministered bit to indicate that this is a
?????????? ??????* portable hotspot.? This will not work in simultaneous AP/STAmode,
???????????????? * nor with P2P.? Need to set the Donlge's MAC address, andthen use that.
???????????????? */
????????????????if(!memcmp(temp_addr, dhd->iflist[0]->mac_addr,
????????????????????????ETHER_ADDR_LEN)) {
??????????????????????? DHD_ERROR(("%sinterface [%s]: set locally administered bit in MAC\n",
??????????????????????? __func__,net->name));
??????????????????????? temp_addr[0] |= 0x02;
??????????????? }
??????? }
?
???????net->hard_header_len = ETH_HLEN + dhd->pub.hdrlen;
#if LINUX_VERSION_CODE >=KERNEL_VERSION(2, 6, 24)
????????net->ethtool_ops = &dhd_ethtool_ops;
#endif /* LINUX_VERSION_CODE>= KERNEL_VERSION(2, 6, 24) */
?
#ifdefined(CONFIG_WIRELESS_EXT)
#if WIRELESS_EXT < 19
????????net->get_wireless_stats = dhd_get_wireless_stats;
#endif /* WIRELESS_EXT < 19*/
#if WIRELESS_EXT > 12
????????net->wireless_handlers = (struct iw_handler_def*)&wl_iw_handler_def;???//這里的初始化工作很重要，之后的ioctl流程會涉及到對它的使用
#endif /* WIRELESS_EXT > 12*/
#endif /*defined(CONFIG_WIRELESS_EXT) */
?
??????? dhd->pub.rxsz =DBUS_RX_BUFFER_SIZE_DHD(net);
????????????????//設置設備地址
????????memcpy(net->dev_addr, temp_addr, ETHER_ADDR_LEN);
?
????????if ((err =register_netdev(net)) != 0) {?????? //注冊net
??????????????? DHD_ERROR(("couldn'tregister the net device, err %d\n", err));
??????????????? goto fail;
??????? }
???????
?
……
}
到這里net網絡設備就被注冊到系統中了，設備準備好了就好對設備進行訪問了
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