gadget驱动框架（三）
usb_udc与usb_gadget_driver的绑定
usb_udc与usb_gadget_driver，在注册的时候分别被添加到udc_list和gadget_driver_pending_list中，无论这两者先后顺序如何，都将会动态的去识别及匹配到具体设备中，绑定过程如下：
源码：drivers/usb/gadget/udc/core.c
/* ------------------------------------------------------------------------- */
static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *driver)
{
int ret;
dev_dbg(&udc->dev, "registering UDC driver [%s]\n",
driver->function);
udc->driver = driver;
udc->dev.driver = &driver->driver;
udc->gadget->dev.driver = &driver->driver;
usb_gadget_udc_set_speed(udc, driver->max_speed);
//调用usb_gadget_driver的bind函数，实体为：composite_driver_template.bind
//具体实现在drivers/usb/gadget/composite.c的composite_bind
ret = driver->bind(udc->gadget, driver);
if (ret)
goto err1;
//调用usb_gadget的udc_start函数，需要udc驱动者实现
//主要功能是启动udc等
//源码：drivers/usb/gadget/udc/s3c2410_udc.c的s3c2410_udc_start
ret = usb_gadget_udc_start(udc);
if (ret) {
driver->unbind(udc->gadget);
goto err1;
}
//调用usb_gadget的pullup函数，上拉或者下拉DP
usb_udc_connect_control(udc);
kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
return 0;
err1:
if (ret != -EISNAM)
dev_err(&udc->dev, "failed to start %s: %d\n",
udc->driver->function, ret);
udc->driver = NULL;
udc->dev.driver = NULL;
udc->gadget->dev.driver = NULL;
return ret;
}
usb_udc_connect_control
源码：drivers/usb/gadget/udc/core.c
static void usb_udc_connect_control(struct usb_udc *udc)
{
//该变量在usb_add_gadget_udc_release创建usb_udc时置为true，
if (udc->vbus)
usb_gadget_connect(udc->gadget);
else
usb_gadget_disconnect(udc->gadget);
}
/**
* usb_gadget_connect - software-controlled connect to USB host
* @gadget:the peripheral being connected
*
* Enables the D+ (or potentially D-) pullup. The host will start
* enumerating this gadget when the pullup is active and a VBUS session
* is active (the link is powered). This pullup is always enabled unless
* usb_gadget_disconnect() has been used to disable it.
*
* Returns zero on success, else negative errno.
*/
int usb_gadget_connect(struct usb_gadget *gadget)
{
int ret = 0;
if (!gadget->ops->pullup) {
ret = -EOPNOTSUPP;
goto out;
}
if (gadget->deactivated) {
/*
* If gadget is deactivated we only save new state.
* Gadget will be connected automatically after activation.
*/
gadget->connected = true;
goto out;
}
//调用usb_gadget的udc_start函数，需要udc驱动者实现
//功能：上拉DP，让host检测到设备的插入
//源码：drivers/usb/gadget/udc/s3c2410_udc.c的s3c2410_udc_pullup
ret = gadget->ops->pullup(gadget, 1);
if (!ret)
gadget->connected = 1;
out:
trace_usb_gadget_connect(gadget, ret);
return ret;
}
/**
* usb_gadget_disconnect - software-controlled disconnect from USB host
* @gadget:the peripheral being disconnected
*
* Disables the D+ (or potentially D-) pullup, which the host may see
* as a disconnect (when a VBUS session is active). Not all systems
* support software pullup controls.
*
* Returns zero on success, else negative errno.
*/
int usb_gadget_disconnect(struct usb_gadget *gadget)
{
int ret = 0;
if (!gadget->ops->pullup) {
ret = -EOPNOTSUPP;
goto out;
}
if (gadget->deactivated) {
/*
* If gadget is deactivated we only save new state.
* Gadget will stay disconnected after activation.
*/
gadget->connected = false;
goto out;
}
//调用usb_gadget的udc_start函数，需要udc驱动者实现
//功能：下拉DP，让host检测到设备的拔出
//源码：drivers/usb/gadget/udc/s3c2410_udc.c的s3c2410_udc_pullup
ret = gadget->ops->pullup(gadget, 0);
if (!ret)
gadget->connected = 0;
out:
trace_usb_gadget_disconnect(gadget, ret);
return ret;
}
usb_gadget_driver的bind与ubind
主要功能是创建usb_composite_dev，及调用usb_composite_driver->bind函数
源码：drivers/usb/gadget/composite.c
static int composite_bind(struct usb_gadget *gadget,
struct usb_gadget_driver *gdriver)
{
struct usb_composite_dev *cdev;
struct usb_composite_driver *composite = to_cdriver(gdriver);
int status = -ENOMEM;
//创建usb_composite_dev
cdev = kzalloc(sizeof *cdev, GFP_KERNEL);
if (!cdev)
return status;
spin_lock_init(&cdev->lock);
cdev->gadget = gadget;
set_gadget_data(gadget, cdev);
//初始化usb_composite_dev的configs链表
INIT_LIST_HEAD(&cdev->configs);
//初始化usb_composite_dev的gstrings链表
INIT_LIST_HEAD(&cdev->gstrings);
//初始化usb_composite_dev.req等
status = composite_dev_prepare(composite, cdev);
if (status)
goto fail;
/* composite gadget needs to assign strings for whole device (like
* serial number), register function drivers, potentially update
* power state and consumption, etc
*/
//回调usb_composite_driver的bind函数，
//实例为gsrial_driver.gsbind，
//源码：drivers/usb/gadget/legacy/serial.c
//主要功能为：初始化设备描述符、字符串描述符等
status = composite->bind(cdev);
if (status < 0)
goto fail;
if (cdev->use_os_string) {
status = composite_os_desc_req_prepare(cdev, gadget->ep0);
if (status)
goto fail;
}
update_unchanged_dev_desc(&cdev->desc, composite->dev);
/* has userspace failed to provide a serial number? */
if (composite->needs_serial && !cdev->desc.iSerialNumber)
WARNING(cdev, "userspace failed to provide iSerialNumber\n");
INFO(cdev, "%s ready\n", composite->name);
return 0;
fail:
__composite_unbind(gadget, false);
return status;
}
static void composite_unbind(struct usb_gadget *gadget)
{
__composite_unbind(gadget, true);
}
static void __composite_unbind(struct usb_gadget *gadget, bool unbind_driver)
{
struct usb_composite_dev *cdev = get_gadget_data(gadget);
struct usb_gadget_strings *gstr = cdev->driver->strings[0];
struct usb_string *dev_str = gstr->strings;
/* composite_disconnect() must already have been called
* by the underlying peripheral controller driver!
* so there's no i/o concurrency that could affect the
* state protected by cdev->lock.
*/
WARN_ON(cdev->config);
while (!list_empty(&cdev->configs)) {
struct usb_configuration *c;
c = list_first_entry(&cdev->configs,
struct usb_configuration, list);
remove_config(cdev, c);
}
if (cdev->driver->unbind && unbind_driver)
cdev->driver->unbind(cdev);
composite_dev_cleanup(cdev);
if (dev_str[USB_GADGET_MANUFACTURER_IDX].s == cdev->def_manufacturer)
dev_str[USB_GADGET_MANUFACTURER_IDX].s = "";
kfree(cdev->def_manufacturer);
kfree(cdev);
set_gadget_data(gadget, NULL);
}
usb_composite_driver的bind与ubind
源码：
static int gs_bind(struct usb_composite_dev *cdev)
{
int status;
/* Allocate string descriptor numbers ... note that string
* contents can be overridden by the composite_dev glue.
*/
status = usb_string_ids_tab(cdev, strings_dev);
if (status < 0)
goto fail;
device_desc.iManufacturer = strings_dev[USB_GADGET_MANUFACTURER_IDX].id;
device_desc.iProduct = strings_dev[USB_GADGET_PRODUCT_IDX].id;
status = strings_dev[STRING_DESCRIPTION_IDX].id;
serial_config_driver.iConfiguration = status;
//otg设备的话，则需要做otg描述符的初始化，本次使用的非otg，暂不分析
if (gadget_is_otg(cdev->gadget)) {
if (!otg_desc[0]) {
struct usb_descriptor_header *usb_desc;
usb_desc = usb_otg_descriptor_alloc(cdev->gadget);
if (!usb_desc) {
status = -ENOMEM;
goto fail;
}
usb_otg_descriptor_init(cdev->gadget, usb_desc);
otg_desc[0] = usb_desc;
otg_desc[1] = NULL;
}
serial_config_driver.descriptors = otg_desc;
serial_config_driver.bmAttributes |= USB_CONFIG_ATT_WAKEUP;
}
/* register our configuration */
if (use_acm) {//acm function，kernel默认将use_acm置为true
status = serial_register_ports(cdev, &serial_config_driver,
"acm");
usb_ep_autoconfig_reset(cdev->gadget);
} else if (use_obex)//obex function，kernel默认将use_acm置为false
status = serial_register_ports(cdev, &serial_config_driver,
"obex");
else {//gser function
status = serial_register_ports(cdev, &serial_config_driver,
"gser");
}
if (status < 0)
goto fail1;
usb_composite_overwrite_options(cdev, &coverwrite);
INFO(cdev, "%s\n", GS_VERSION_NAME);
return 0;
fail1:
kfree(otg_desc[0]);
otg_desc[0] = NULL;
fail:
return status;
}
static int gs_unbind(struct usb_composite_dev *cdev)
{
int i;
for (i = 0; i < n_ports; i++) {
usb_put_function(f_serial[i]);
usb_put_function_instance(fi_serial[i]);
}
kfree(otg_desc[0]);
otg_desc[0] = NULL;
return 0;
}
serial_register_ports的function的bind
static int serial_register_ports(struct usb_composite_dev *cdev,
struct usb_configuration *c, const char *f_name)
{
int i;
int ret;
//通过bConfigurationValue判断当前config，是否在cdev->configs链表中
//在，则报错；不在，则添加到链表中
ret = usb_add_config_only(cdev, c);
if (ret)
goto out;
for (i = 0; i < n_ports; i++) {
//根据f_name匹配相关的usb_function_instance
//源码：drivers/usb/gadget/functions.c
fi_serial[i] = usb_get_function_instance(f_name);
if (IS_ERR(fi_serial[i])) {
ret = PTR_ERR(fi_serial[i]);
goto fail;
}
//调用usb_function_instance的alloc_func申请usb_function
//源码：drivers/usb/gadget/function/f_acm.c
f_serial[i] = usb_get_function(fi_serial[i]);
if (IS_ERR(f_serial[i])) {
ret = PTR_ERR(f_serial[i]);
goto err_get_func;
}
//将申请到的usb_function添加到config->functions链表中
//源码：drivers/usb/gadget/composite.c
ret = usb_add_function(c, f_serial[i]);
if (ret)
goto err_add_func;
}
return 0;
err_add_func:
usb_put_function(f_serial[i]);
err_get_func:
usb_put_function_instance(fi_serial[i]);
fail:
i--;
while (i >= 0) {
usb_remove_function(c, f_serial[i]);
usb_put_function(f_serial[i]);
usb_put_function_instance(fi_serial[i]);
i--;
}
out:
return ret;
}
static struct usb_function_instance *try_get_usb_function_instance(const char *name)
{
struct usb_function_driver *fd;
struct usb_function_instance *fi;
fi = ERR_PTR(-ENOENT);
mutex_lock(&func_lock);
//name="acm"，遍历func_list，查找"acm"所对应的usb_function_driver
list_for_each_entry(fd, &func_list, list) {
if (strcmp(name, fd->name))
continue;
if (!try_module_get(fd->mod)) {
fi = ERR_PTR(-EBUSY);
break;
}
//调用usb_function_driver.alloc_inst申请usb_function_instance
fi = fd->alloc_inst();
if (IS_ERR(fi))
module_put(fd->mod);
else
fi->fd = fd;
break;
}
mutex_unlock(&func_lock);
return fi;
}
struct usb_function_instance *usb_get_function_instance(const char *name)
{
struct usb_function_instance *fi;
int ret;
//name="acm"，通过该name获取usb_function_instance
fi = try_get_usb_function_instance(name);
if (!IS_ERR(fi))
return fi;
ret = PTR_ERR(fi);
if (ret != -ENOENT)
return fi;
ret = request_module("usbfunc:%s", name);
if (ret < 0)
return ERR_PTR(ret);
return try_get_usb_function_instance(name);
}
struct usb_function *usb_get_function(struct usb_function_instance *fi)
{
struct usb_function *f;
//调用usb_function_instance的alloc_func申请usb_function
f = fi->fd->alloc_func(fi);
if (IS_ERR(f))
return f;
f->fi = fi;
return f;
}
EXPORT_SYMBOL_GPL(usb_get_function);
usb_configuration与usb_functionn的bind
/**
* usb_add_function() - add a function to a configuration
* @config: the configuration
* @function: the function being added
* Context: single threaded during gadget setup
*
* After initialization, each configuration must have one or more
* functions added to it. Adding a function involves calling its @bind()
* method to allocate resources such as interface and string identifiers
* and endpoints.
*
* This function returns the value of the function's bind(), which is
* zero for success else a negative errno value.
*/
int usb_add_function(struct usb_configuration *config,
struct usb_function *function)
{
int value = -EINVAL;
DBG(config->cdev, "adding '%s'/%p to config '%s'/%p\n",
function->name, function,
config->label, config);
if (!function->set_alt || !function->disable)
goto done;
function->config = config;
//将function添加到config->functions链表中
list_add_tail(&function->list, &config->functions);
if (function->bind_deactivated) {
value = usb_function_deactivate(function);
if (value)
goto done;
}
/* REVISIT *require* function->bind? */
if (function->bind) {
value = function->bind(config, function);
if (value < 0) {
list_del(&function->list);
function->config = NULL;
}
} else
value = 0;
/* We allow configurations that don't work at both speeds.
* If we run into a lowspeed Linux system, treat it the same
* as full speed ... it's the function drivers that will need
* to avoid bulk and ISO transfers.
*/
if (!config->fullspeed && function->fs_descriptors)
config->fullspeed = true;
if (!config->highspeed && function->hs_descriptors)
config->highspeed = true;
if (!config->superspeed && function->ss_descriptors)
config->superspeed = true;
if (!config->superspeed_plus && function->ssp_descriptors)
config->superspeed_plus = true;
done:
if (value)
DBG(config->cdev, "adding '%s'/%p --> %d\n",
function->name, function, value);
return value;
}
小结
到此已分析完usb_udc、usb_gadget_driver的绑定过程，及usb_function的匹配过程。。下一节将详细介绍usb_function的注册过程及相关函数的分析。另外一个方面，udc控制器已将DP上拉，udc endpoint0已使能，静待插入host完成枚举
标签：function,USB,框架,gadget,driver,udc,cdev,usb From： https://www.cnblogs.com/linhaostudy/p/18395958