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USB peripheral driver - configfs
2022-06-23 08:25:00 【Be good to me】
1. configfs init
1.1 configfs usage
Reference documents ：msm-kernel\Documentation\usb\gadget_configfs.rst
(1) Creating the gadgets:
mkdir /config/usb_gadget/g3 // mkdir $CONFIGFS_HOME/usb_gadget/<gadget name>
Bottom call gadget_make()
(2) Creating the configurations:
cd /config/usb_gadget/g3
mkdir configs/c.1 // mkdir configs/<name>.<number>
(3) Creating the functions:
mkdir functions/ncm.usb0 // mkdir functions/<name>.<instance name>
Bottom call function_make()
(4) Associating the functions with their configurations:
ln -s functions/ncm.usb0 configs/c.1 // ln -s functions/<name>.<instance name> configs/<name>.<number>
Bottom call ：config_usb_cfg_link()
(5) Enabling the gadget：
echo <udc name> > UDC
echo "a600000.dwc3" > UDC
Bottom call ：gadget_dev_desc_UDC_store()
1.2 configfs init file
== init.rc // Source path \system\core\rootdir\init.rc
== import /vendor/etc/init/hw/init.${
ro.hardware}.rc
== init.qcom.rc // Source path \device\qcom\common\rootdir\etc
== import init.qcom.usb.rc // filesystem route /vendor/etc/init/hw/
== import init.msm.usb.configfs.rc
== import init.target.rc
1.2.1 init.qcom.usb.rc
This configuration file is used for ：
（1） Create device gadget;
（2） Create a configuration config;
（3） Create an interface function.
on boot
write /sys/class/android_usb/android0/iSerial ${
ro.serialno}
mount configfs none /config // mount configfs
mkdir /config/usb_gadget/g1 0770 // （1） Create device gadget
mkdir /config/usb_gadget/g2 0770
mkdir /config/usb_gadget/g1/strings/0x409 0770
mkdir /config/usb_gadget/g2/strings/0x409 0770
write /config/usb_gadget/g1/bcdUSB 0x0200
write /config/usb_gadget/g2/bcdUSB 0x0200
write /config/usb_gadget/g1/os_desc/use 1
write /config/usb_gadget/g1/strings/0x409/serialnumber ${
ro.serialno}
write /config/usb_gadget/g2/strings/0x409/serialnumber ${
ro.serialno}
write /config/usb_gadget/g1/strings/0x409/manufacturer ${
ro.product.manufacturer}
write /config/usb_gadget/g2/strings/0x409/manufacturer ${
ro.product.manufacturer}
write /config/usb_gadget/g1/strings/0x409/product ${
ro.product.model}
write /config/usb_gadget/g2/strings/0x409/product ${
ro.product.model}
mkdir /config/usb_gadget/g1/functions/mass_storage.0 // （3） Create an interface function
mkdir /config/usb_gadget/g1/functions/mtp.gs0
mkdir /config/usb_gadget/g1/functions/ptp.gs1
mkdir /config/usb_gadget/g1/functions/accessory.gs2
mkdir /config/usb_gadget/g1/functions/audio_source.gs3
mkdir /config/usb_gadget/g1/functions/midi.gs5
mkdir /config/usb_gadget/g1/functions/ffs.adb
mkdir /config/usb_gadget/g1/functions/diag.diag
mkdir /config/usb_gadget/g1/functions/diag.diag_mdm
mkdir /config/usb_gadget/g1/functions/cser.dun.0
mkdir /config/usb_gadget/g1/functions/cser.nmea.1
mkdir /config/usb_gadget/g1/functions/cser.dun.2
mkdir /config/usb_gadget/g1/functions/gsi.rmnet
mkdir /config/usb_gadget/g1/functions/gsi.rndis
mkdir /config/usb_gadget/g1/functions/gsi.dpl
mkdir /config/usb_gadget/g1/functions/qdss.qdss
mkdir /config/usb_gadget/g1/functions/qdss.qdss_mdm
mkdir /config/usb_gadget/g1/functions/rndis_bam.rndis
mkdir /config/usb_gadget/g1/functions/rndis.rndis
mkdir /config/usb_gadget/g1/functions/rmnet_bam.rmnet
mkdir /config/usb_gadget/g1/functions/rmnet_bam.dpl
mkdir /config/usb_gadget/g1/functions/rmnet_bam.rmnet_bam_dmux
mkdir /config/usb_gadget/g1/functions/rmnet_bam.dpl_bam_dmux
mkdir /config/usb_gadget/g1/functions/ncm.0
mkdir /config/usb_gadget/g1/functions/ccid.ccid
mkdir /config/usb_gadget/g1/functions/uac2.0
mkdir /config/usb_gadget/g1/functions/uvc.0
mkdir /config/usb_gadget/g1/functions/uvc.1
mkdir /config/usb_gadget/g1/functions/hid.0
mkdir /config/usb_gadget/g1/functions/hid.1
mkdir /config/usb_gadget/g1/functions/hid.2
mkdir /config/usb_gadget/g1/functions/hid.3
mkdir /config/usb_gadget/g1/functions/hid.4
mkdir /config/usb_gadget/g1/functions/hid.5
mkdir /config/usb_gadget/g1/configs/b.1 0770 //（2） Create a configuration config
mkdir /config/usb_gadget/g2/configs/b.1 0770
mkdir /config/usb_gadget/g1/configs/b.1/strings/0x409 0770
mkdir /config/usb_gadget/g2/configs/b.1/strings/0x409 0770
write /config/usb_gadget/g1/os_desc/b_vendor_code 0x1
write /config/usb_gadget/g1/os_desc/qw_sign "MSFT100"
symlink /config/usb_gadget/g1/configs/b.1 /config/usb_gadget/g1/os_desc/b.1
mkdir /dev/usb-ffs 0775 shell system
mkdir /dev/usb-ffs/adb 0770 shell system
mount functionfs adb /dev/usb-ffs/adb uid=2000,gid=1000,rmode=0770,fmode=0660
write /sys/class/android_usb/android0/f_ffs/aliases adb
setprop sys.usb.mtp.device_type 2
setprop vendor.usb.controller ${
sys.usb.controller}
enable vendor.qcom-usb-sh
1.2.1 init.msm.usb.configfs.rc
This configuration file is used to read the upper layer property, then enable Corresponding config All of the function.
// sys.usb.config=diag,adb Indicates that the configuration has diag and adb Two interface functions ;
// You can use getprop sys.usb.config The query ,setprop sys.usb.config=** Perform configuration switching
on property:sys.usb.ffs.ready=1 && property:sys.usb.config=diag,adb && property:sys.usb.configfs=1
write /config/usb_gadget/g1/configs/b.1/strings/0x409/configuration "diag_adb"
rm /config/usb_gadget/g1/configs/b.1/f1
rm /config/usb_gadget/g1/configs/b.1/f2
rm /config/usb_gadget/g1/configs/b.1/f3
rm /config/usb_gadget/g1/configs/b.1/f4
rm /config/usb_gadget/g1/configs/b.1/f5
rm /config/usb_gadget/g1/configs/b.1/f6
rm /config/usb_gadget/g1/configs/b.1/f7
rm /config/usb_gadget/g1/configs/b.1/f8
rm /config/usb_gadget/g1/configs/b.1/f9
rm /config/usb_gadget/g1/configs/b.1/f10
rm /config/usb_gadget/g1/configs/b.1/f11
write /config/usb_gadget/g1/idVendor 0x05C6
write /config/usb_gadget/g1/idProduct 0x901D
symlink /config/usb_gadget/g1/functions/diag.diag /config/usb_gadget/g1/configs/b.1/f1
symlink /config/usb_gadget/g1/functions/ffs.adb /config/usb_gadget/g1/configs/b.1/f2
write /config/usb_gadget/g1/UDC ${
sys.usb.controller}
setprop sys.usb.state ${
sys.usb.config}
2. Driver module initialization
2.1 function Drive initialization
be-all function Drivers are registered in a linked list func_list, When configfs When the drive is started , Read the upper layer configuration function To match with the list .
stay \drivers\usb\gadget\function\f_fs.c in , Use the following macro to register function drive （ take usb_function_driver Join in func_list Linked list ）, The init The operation will be executed when the system is initialized .
#define DECLARE_USB_FUNCTION_INIT(_name, _inst_alloc, _func_alloc) \ DECLARE_USB_FUNCTION(_name, _inst_alloc, _func_alloc) \ static int __init _name ## mod_init(void) \ {
\ return usb_function_register(&_name ## usb_func); \ } \ static void __exit _name ## mod_exit(void) \ {
\ usb_function_unregister(&_name ## usb_func); \ } \ module_init(_name ## mod_init); \ module_exit(_name ## mod_exit)
2.2 configfs Drive initialization
\drivers\usb\gadget\configfs.c
Initialize when the system loads the driver module gadget configfs, Including some operation interfaces provided to the upper layer （mkdir write…）
== module_init(gadget_cfs_init);
== configfs_register_subsystem(&gadget_subsys);
gadget_subsys == gadgets_type == gadgets_ops
== gadgets_make(); //gadget_make Will be executed at the upper level mkdir Called when
== struct gadget_info *gi; // structure gadget_info
== gi->composite.gadget_driver = configfs_driver_template; // structure usb_gadget_driver
struct gadget_info {
struct usb_composite_driver composite;
struct usb_composite_dev cdev;
};
static const struct usb_gadget_driver configfs_driver_template = {
//usb_gadget_driver
.bind = configfs_composite_bind,
.unbind = configfs_composite_unbind,
#ifdef CONFIG_USB_CONFIGFS_UEVENT
.setup = android_setup,
#else
.setup = configfs_composite_setup,
#endif
.reset = configfs_composite_reset,
.disconnect = configfs_composite_disconnect,
.suspend = configfs_composite_suspend,
.resume = configfs_composite_resume,
};
3. The bottom layer corresponds to the interface of the upper layer
3.1 function_make
The upper ：mkdir /config/usb_gadget/g1/functions/diag.diag
Bottom ：function_make()
static struct config_group *function_make(
struct config_group *group,
const char *name)
function_make Call the process ：
== configfs_mkdir();
== function_make(struct config_group *group, const char *name);
== usb_get_function_instance();
== try_get_usb_function_instance(const char *name); // from func_list Find fd
fd->alloc_inst();
== ncm_alloc_inst();
== create_function_device();
== device_create();
== device_add();
3.2 gadget connect
The upper ：echo “a600000.dwc3” > UDC
kernel 5.4:
== gadget_dev_desc_UDC_store(); // \drivers\usb\gadget\configfs.c
== usb_gadget_probe_driver(struct usb_gadget_driver *driver) // \drivers\usb\gadget\udc\core.c
== udc_bind_to_driver(); // binding usb_gadget_driver And usb_udc
== driver->bind(udc->gadget, driver);
== configfs_composite_bind();
== usb_add_function(c, f); // add to function, perform function Function of
== usb_gadget_udc_start(udc);
== udc->gadget->ops->udc_start(udc->gadget, udc->driver);
== dwc3_gadget_start();
== request_threaded_irq(irq, dwc3_interrupt, dwc3_thread_interrupt, IRQF_SHARED, "dwc3", dwc->ev_buf);
// register dwc3 interrupt , When host When you send a message , Trigger interrupt function
== usb_udc_connect_control(struct usb_udc *udc)
== usb_gadget_connect(struct usb_gadget *gadget)
== gadget->ops->pullup(gadget, 1);
== dwc3_gadget_pullup(struct usb_gadget *g, int is_on);
== dwc3_gadget_run_stop_util();
== dwc3_gadget_run_stop(dwc, true, false);
== __dwc3_gadget_start(dwc); //enable Endpoint transport
== __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action) // initializes a hw endpoint
3.2 gadget disconnect
The upper ：echo “none” > UDC
== gadget_dev_desc_UDC_store
== unregister_gadget(struct gadget_info *gi)
== usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
== usb_gadget_remove_driver(struct usb_udc *udc)
static void usb_gadget_remove_driver(struct usb_udc *udc)
{
dev_dbg(&udc->dev, "unregistering UDC driver [%s]\n",
udc->driver->function);
kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE); // Produce a uevent Report
usb_gadget_disconnect(udc->gadget); //gadget Drive off
if (udc->gadget->irq)
synchronize_irq(udc->gadget->irq);
udc->driver->unbind(udc->gadget); // Cancel req（gadget The endpoint of 0 usb_ep）
usb_gadget_udc_stop(udc); //udc stop it
udc->driver = NULL;
udc->dev.driver = NULL;
udc->gadget->dev.driver = NULL;
}
3.2.1 disable The endpoint of the controller dwc3_ep（32 individual ）
== usb_gadget_disconnect(struct usb_gadget *gadget)
gadget->ops->pullup(gadget, 0);
.pullup = dwc3_gadget_pullup,
== dwc3_gadget_pullup(struct usb_gadget *g, int is_on) // open / Close endpoint 、 Write register
== dwc3_stop_active_transfers(dwc); // Not 0 Endpoint
== dwc3_remove_requests(dwc, dep);
== __dwc3_gadget_stop(struct dwc3 *dwc) // disable Endpoint 0（ Control endpoints ） transmission
== __dwc3_gadget_ep_disable(struct dwc3_ep *dep) // disables a hw endpoint
== dwc3_remove_requests(struct dwc3 *dwc, struct dwc3_ep *dep)
3.2.2 Cancel req（gadget The endpoint of 0 usb_ep）
== udc->driver->unbind(udc->gadget);
.unbind = composite_unbind,
.unbind = configfs_composite_unbind,
== configfs_composite_unbind(struct usb_gadget *gadget)
== composite_dev_cleanup(struct usb_composite_dev *cdev) // eliminate composite dev Upper req
== usb_ep_dequeue(struct usb_ep *ep, struct usb_request *req) // dequeues (cancels, unlinks) an I/O request from an endpoint
== ret = ep->ops->dequeue(ep, req);
.dequeue = dwc3_gadget_ep_dequeue, //usb_ep Turn into dwc3_ep
==dwc3_gadget_ep_dequeue(struct usb_ep *ep, struct usb_request *request)
4. Once complete Gadget Data flow
Configfs The data exchange between the subsystem and the controller is through struct usb_request *request Structure , A complete process is as follows ：
4.1 function apply req
\drivers\usb\gadget\function\f_fs.c
（1） apply req：
== ffs->ep0req = usb_ep_alloc_request(cdev->gadget->ep0, GFP_KERNEL); trace_usb_ep_alloc_request(ep, req, req ? 0 : -ENOMEM);
== ep->ops->alloc_request(ep, gfp_flags);
== dwc3_gadget_ep_alloc_request(); trace_dwc3_alloc_request(req);
== ffs->ep0req->complete = ffs_ep0_complete; // req Completion function of
Release req：
== ffs_func_unbind();
== usb_ep_free_request(); trace_usb_ep_free_request(ep, req, 0);
== ep->ops->free_request(ep, req);
== dwc3_gadget_ep_free_request(); trace_dwc3_free_request();
（2） take req Submit to controller ：
== usb_ep_queue(ffs->gadget->ep0, req, GFP_ATOMIC); trace_usb_ep_queue(ep, req, ret);
== ret = ep->ops->queue(ep, req, gfp_flags);
== dwc3_gadget_ep0_queue();
== __dwc3_gadget_ep0_queue();
== __dwc3_ep0_do_control_data();
== dwc3_ep0_start_trans();
== dwc3_send_gadget_ep_cmd(); trace_dwc3_gadget_ep_cmd(dep, cmd, params, cmd_status);
== dwc3_writel(dep->regs, DWC3_DEPCMDPAR0, params->param0);
4.2 Controller processing req （ Write register ）
== dwc3_gadget_ep_queue();
== __dwc3_gadget_ep_queue();
== __dwc3_gadget_start_isoc(struct dwc3_ep *dep);
==__dwc3_gadget_kick_transfer(struct dwc3_ep *dep);
== dwc3_send_gadget_ep_cmd(); // This function will issue @cmd with given @params to @dep and wait for its completion.
== dwc3_writel(void __iomem *base, u32 offset, u32 value)
4.3 Controller return req （ Interrupt callback function ）
== dwc3_gadget_start(); // Registration interrupted
== request_threaded_irq(irq, dwc3_interrupt, dwc3_thread_interrupt, IRQF_SHARED, "dwc3", dwc->ev_buf);
== dwc3_thread_interrupt(); // Interrupt generation （host Send a message ）, Call callback function
== dwc3_process_event_buf(); // Handling interrupt events buf(dwc3_event_buffer )
== dwc3_process_event_entry(); trace_dwc3_event(event->raw, dwc);
== dwc3_endpoint_interrupt(); // Interruption of endpoint processing
== dwc3_ep0_interrupt(); // Control transmission if (epnum == 0 || epnum == 1)
== dwc3_ep0_xfer_complete(); //event->endpoint_event = DWC3_DEPEVT_XFERCOMPLETE
== dwc3_ep0_inspect_setup(); //dwc->ep0state = EP0_SETUP_PHASE
//dwc3_ep0_std_request() == dwc3_ep0_set_config()
== dwc3_ep0_delegate_req();
== dwc->gadget_driver->setup(&dwc->gadget, ctrl);
== configfs_composite_setup();
== composite_setup(); //setup Including getting descriptors , To configure , Address and other operations
== set_config(cdev, ctrl, w_value); ctrl->bRequest = USB_REQ_SET_CONFIGURATION
== dwc3_gadget_endpoint_transfer_complete(); // Transmission complete
== dwc3_gadget_endpoint_trbs_complete();
== dwc3_gadget_ep_cleanup_completed_requests()
== dwc3_gadget_giveback(); // The data returned
== dwc3_gadget_del_and_unmap_request(); trace_dwc3_gadget_giveback(req);
== usb_gadget_giveback_request() trace_usb_gadget_giveback_request(ep, req, 0);// give the request back to the gadget layer
== req->complete(ep, req);
== ffs_ep0_complete() // function Completion function of
== dwc3_gadget_interrupt(dwc, &event->devt); // Yes gadget The interruption of the device
== usb_gadget_vbus_draw(&dwc->gadget, 2); trace_usb_gadget_vbus_draw(gadget, ret);
== gadget->ops->vbus_draw(gadget, mA);
== dwc3_gadget_vbus_draw();
== dwc3_notify_event(dwc, DWC3_CONTROLLER_SET_CURRENT_DRAW_EVENT, 0);
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