USB device stack, with KL25Z fixes for USB 3.0 hosts and sleep/resume interrupt handling

Dependents:   frdm_Slider_Keyboard idd_hw2_figlax_PanType idd_hw2_appachu_finger_chording idd_hw3_AngieWangAntonioDeLimaFernandesDanielLim_BladeSymphony ... more

Fork of USBDevice by mbed official

This is an overhauled version of the standard mbed USB device-side driver library, with bug fixes for KL25Z devices. It greatly improves reliability and stability of USB on the KL25Z, especially with devices using multiple endpoints concurrently.

I've had some nagging problems with the base mbed implementation for a long time, manifesting as occasional random disconnects that required rebooting the device. Recently (late 2015), I started implementing a USB device on the KL25Z that used multiple endpoints, and suddenly the nagging, occasional problems turned into frequent and predictable crashes. This forced me to delve into the USB stack and figure out what was really going on. Happily, the frequent crashes made it possible to track down and fix the problems. This new version is working very reliably in my testing - the random disconnects seem completely eradicated, even under very stressful conditions for the device.

Summary

  • Overall stability improvements
  • USB 3.0 host support
  • Stalled endpoint fixes
  • Sleep/resume notifications
  • Smaller memory footprint
  • General code cleanup

Update - 2/15/2016

My recent fixes introduced a new problem that made the initial connection fail most of the time on certain hosts. It's not clear if the common thread was a particular type of motherboard or USB chip set, or a specific version of Windows, or what, but several people ran into it. We tracked the problem down to the "stall" fixes in the earlier updates, which we now know weren't quite the right fixes after all. The latest update (2/15/2016) fixes this. It has new and improved "unstall" handling that so far works well with diverse hosts.

Race conditions and overall stability

The base mbed KL25Z implementation has a lot of problems with "race conditions" - timing problems that can happen when hardware interrupts occur at inopportune moments. The library shares a bunch of static variable data between interrupt handler context and regular application context. This isn't automatically a bad thing, but it does require careful coordination to make sure that the interrupt handler doesn't corrupt data that the other code was in the middle of updating when an interrupt occurs. The base mbed code, though, doesn't do any of the necessary coordination. This makes it kind of amazing that the base code worked at all for anyone, but I guess the interrupt rate is low enough in most applications that the glitch rate was below anyone's threshold to seriously investigate.

This overhaul adds the necessary coordination for the interrupt handlers to protect against these data corruptions. I think it's very solid now, and hopefully entirely free of the numerous race conditions in the old code. It's always hard to be certain that you've fixed every possible bug like this because they strike (effectively) at random, but I'm pretty confident: my test application was reliably able to trigger glitches in the base code in a matter of minutes, but the same application (with the overhauled library) now runs for days on end without dropping the connection.

Stalled endpoint fixes

USB has a standard way of handling communications errors called a "stall", which basically puts the connection into an error mode to let both sides know that they need to reset their internal states and sync up again. The original mbed version of the USB device library doesn't seem to have the necessary code to recover from this condition properly. The KL25Z hardware does some of the work, but it also seems to require the software to take some steps to "un-stall" the connection. (I keep saying "seems to" because the hardware reference material is very sketchy about all of this. Most of what I've figured out is from observing the device in action with a Windows host.) This new version adds code to do the necessary re-syncing and get the connection going again, automatically, and transparently to the user.

USB 3.0 Hosts

The original mbed code sometimes didn't work when connecting to hosts with USB 3.0 ports. This didn't affect every host, but it affected many of them. The common element seemed to be the Intel Haswell chip set on the host, but there may be other chip sets affected as well. In any case, the problem affected many PCs from the Windows 7 and 8 generation, as well as many Macs. It was possible to work around the problem by avoiding USB 3.0 ports - you could use a USB 2 port on the host, or plug a USB 2 hub between the host and device. But I wanted to just fix the problem and eliminate the need for such workarounds. This modified version of the library has such a fix, which so far has worked for everyone who's tried.

Sleep/resume notifications

This modified version also contains an innocuous change to the KL25Z USB HAL code to handle sleep and resume interrupts with calls to suspendStateChanged(). The original KL25Z code omitted these calls (and in fact didn't even enable the interrupts), but I think this was an unintentional oversight - the notifier function is part of the generic API, and other supported boards all implement it. I use this feature in my own application so that I can distinguish sleep mode from actual disconnects and handle the two conditions correctly.

Smaller memory footprint

The base mbed version of the code allocates twice as much memory for USB buffers as it really needed to. It looks like the original developers intended to implement the KL25Z USB hardware's built-in double-buffering mechanism, but they ultimately abandoned that effort. But they left in the double memory allocation. This version removes that and allocates only what's actually needed. The USB buffers aren't that big (128 bytes per endpoint), so this doesn't save a ton of memory, but even a little memory is pretty precious on this machine given that it only has 16K.

(I did look into adding the double-buffering support that the original developers abandoned, but after some experimentation I decided they were right to skip it. It just doesn't seem to mesh well with the design of the rest of the mbed USB code. I think it would take a major rewrite to make it work, and it doesn't seem worth the effort given that most applications don't need it - it would only benefit applications that are moving so much data through USB that they're pushing the limits of the CPU. And even for those, I think it would be a lot simpler to build a purely software-based buffer rotation mechanism.)

General code cleanup

The KL25Z HAL code in this version has greatly expanded commentary and a lot of general cleanup. Some of the hardware constants were given the wrong symbolic names (e.g., EVEN and ODD were reversed), and many were just missing (written as hard-coded numbers without explanation). I fixed the misnomers and added symbolic names for formerly anonymous numbers. Hopefully the next person who has to overhaul this code will at least have an easier time understanding what I thought I was doing!

USBDevice/USBDevice.h

Committer:
mjr
Date:
2017-03-17
Revision:
54:2e181d51495a
Parent:
53:c8110529c24b

File content as of revision 54:2e181d51495a:

/* Copyright (c) 2010-2011 mbed.org, MIT License
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software
* and associated documentation files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all copies or
* substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
* BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#ifndef USBDEVICE_H
#define USBDEVICE_H

#include "mbed.h"
#include "USBDevice_Types.h"
#include "USBHAL.h"

class USBDevice: public USBHAL
{
public:
    USBDevice(uint16_t vendor_id, uint16_t product_id, uint16_t product_release);

    /*
    * Check if the device is configured
    *
    * @returns true if configured, false otherwise
    */
    bool configured(void);

    /*
    * Connect a device
    *
    * @param blocking: block if not configured
    */
    void connect(bool blocking = true);

    /*
    * Disconnect a device
    */
    void disconnect(void);

    /*
    * Add an endpoint
    *
    * @param endpoint endpoint which will be added
    * @param maxPacket Maximum size of a packet which can be sent for this endpoint
    * @returns true if successful, false otherwise
    */
    bool addEndpoint(uint8_t endpoint, uint32_t maxPacket);

    /*
    * Start a reading on a certain endpoint.
    * You can access the result of the reading by USBDevice_read
    *
    * @param endpoint endpoint which will be read
    * @param maxSize the maximum length that can be read
    * @return true if successful
    */
    bool readStart(uint8_t endpoint, uint32_t maxSize);

    /*
    * Read a certain endpoint. Before calling this function, USBUSBDevice_readStart
    * must be called.
    *
    * Warning: blocking
    *
    * @param endpoint endpoint which will be read
    * @param buffer buffer will be filled with the data received
    * @param size the number of bytes read will be stored in *size
    * @param maxSize the maximum length that can be read
    * @returns true if successful
    */
    bool readEP(uint8_t endpoint, uint8_t * buffer, uint32_t * size, uint32_t maxSize);

    /*
    * Read a certain endpoint.
    *
    * Warning: non blocking
    *
    * @param endpoint endpoint which will be read
    * @param buffer buffer will be filled with the data received (if data are available)
    * @param size the number of bytes read will be stored in *size
    * @param maxSize the maximum length that can be read
    * @returns true if successful
    */
    bool readEP_NB(uint8_t endpoint, uint8_t * buffer, uint32_t * size, uint32_t maxSize);

    /*
    * Write a certain endpoint.
    *
    * Warning: blocking
    *
    * @param endpoint endpoint to write
    * @param buffer data contained in buffer will be write
    * @param size the number of bytes to write
    * @param maxSize the maximum length that can be written on this endpoint
    */
    bool write(uint8_t endpoint, uint8_t * buffer, uint32_t size, uint32_t maxSize);


    /*
    * Write a certain endpoint.
    *
    * Warning: non blocking
    *
    * @param endpoint endpoint to write
    * @param buffer data contained in buffer will be write
    * @param size the number of bytes to write
    * @param maxSize the maximum length that can be written on this endpoint
    */
    bool writeNB(uint8_t endpoint, uint8_t * buffer, uint32_t size, uint32_t maxSize);

    /**
    * Write a certain endpoint.  Blocks until the report has been sent successfully,
    * or until the timeout expires, whichever comes first.  
    *
    * @param endpoint endpoint to write
    * @param buffer data contained in buffer will be write
    * @param size the number of bytes to write
    * @param maxSize the maximum length that can be written on this endpoint
    * @param timeout_ms timeout in milliseconds
    * @returns true if successful, false on error or timeout
    */
    bool writeTO(uint8_t endpoint, uint8_t * buffer, uint32_t size, uint32_t maxSize, int timeout_ms);    

    /*
    * Called by USBDevice layer on bus reset. Warning: Called in ISR context
    *
    * May be used to reset state
    */
    virtual void USBCallback_busReset(void) {};

    /*
    * Called by USBDevice on Endpoint0 request. Warning: Called in ISR context
    * This is used to handle extensions to standard requests
    * and class specific requests
    *
    * @returns true if class handles this request
    */
    virtual bool USBCallback_request() { return false; };

    /*
    * Called by USBDevice on Endpoint0 request completion
    * if the 'notify' flag has been set to true. Warning: Called in ISR context
    *
    * In this case it is used to indicate that a HID report has
    * been received from the host on endpoint 0
    *
    * @param buf buffer received on endpoint 0
    * @param length length of this buffer
    */
    virtual void USBCallback_requestCompleted(uint8_t * buf, uint32_t length) {};

    /*
    * Called by USBDevice layer. Set configuration of the device.
    * For instance, you can add all endpoints that you need on this function.
    *
    * @param configuration Number of the configuration
    */
    virtual bool USBCallback_setConfiguration(uint8_t configuration) { return false; };

    /*
     * Called by USBDevice layer. Set interface/alternate of the device.
     *
     * @param interface Number of the interface to be configured
     * @param alternate Number of the alternate to be configured
     * @returns true if class handles this request
     */
    virtual bool USBCallback_setInterface(uint16_t interface, uint8_t alternate) { return false; }
    virtual bool USBCallback_getInterface(uint16_t interface, uint8_t *alternate) { return false; }

    /*
    * Get device descriptor. Warning: this method has to store the length of the report descriptor in reportLength.
    *
    * @returns pointer to the device descriptor
    */
    virtual const uint8_t *deviceDesc();

    /*
    * Get configuration descriptor
    *
    * @returns pointer to the configuration descriptor
    */
    virtual const uint8_t *configurationDesc(){return NULL;};

    /*
    * Get string lang id descriptor
    *
    * @return pointer to the string lang id descriptor
    */
    virtual const uint8_t *stringLangidDesc();

    /*
    * Get string manufacturer descriptor
    *
    * @returns pointer to the string manufacturer descriptor
    */
    virtual const uint8_t *stringImanufacturerDesc();

    /*
    * Get string product descriptor
    *
    * @returns pointer to the string product descriptor
    */
    virtual const uint8_t *stringIproductDesc();

    /*
    * Get string serial descriptor
    *
    * @returns pointer to the string serial descriptor
    */
    virtual const uint8_t *stringIserialDesc();

    /*
    * Get string configuration descriptor
    *
    * @returns pointer to the string configuration descriptor
    */
    virtual const uint8_t *stringIConfigurationDesc();

    /*
    * Get string interface descriptor
    *
    * @returns pointer to the string interface descriptor
    */
    virtual const uint8_t *stringIinterfaceDesc();


protected:
    virtual void busReset(void);
    virtual void EP0setupCallback(void);
    virtual void EP0out(void);
    virtual void EP0in(void);
    virtual void setDeviceState(DEVICE_STATE state) { device.state = state; }
    virtual void connectStateChanged(unsigned int connected);
    virtual void suspendStateChanged(unsigned int suspended);
    virtual void sleepStateChanged(unsigned int sleep);
    const uint8_t *findDescriptor(uint8_t descriptorType, int idx);
    CONTROL_TRANSFER *getTransferPtr(void);

    uint16_t VENDOR_ID;
    uint16_t PRODUCT_ID;
    uint16_t PRODUCT_RELEASE;

private:
    bool addRateFeedbackEndpoint(uint8_t endpoint, uint32_t maxPacket);
    bool requestGetDescriptor(void);
    bool controlOut(void);
    bool controlIn(void);
    bool requestSetAddress(void);
    bool requestSetConfiguration(void);
    bool requestSetFeature(void);
    bool requestClearFeature(void);
    bool requestGetStatus(void);
    bool requestSetup(void);
    bool controlSetup(void);
    void decodeSetupPacket(uint8_t *data, SETUP_PACKET *packet);
    bool requestGetConfiguration(void);
    virtual bool requestGetInterface(void);
    virtual bool requestSetInterface(void);

    CONTROL_TRANSFER transfer;
    USB_DEVICE device;
};


#endif