can.hpp

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/*
 * Copyright (C) 2014 Pavel Kirienko <pavel.kirienko@gmail.com>
 */

#pragma once

#include <uavcan_stm32/build_config.hpp>
#include <uavcan_stm32/thread.hpp>
#include <uavcan/driver/can.hpp>
#include <uavcan_stm32/bxcan.hpp>

namespace uavcan_stm32
{
/**
 * Driver error codes.
 * These values can be returned from driver functions negated.
 */
//static const uavcan::int16_t ErrUnknown               = 1000; ///< Reserved for future use
static const uavcan::int16_t ErrNotImplemented          = 1001; ///< Feature not implemented
static const uavcan::int16_t ErrInvalidBitRate          = 1002; ///< Bit rate not supported
static const uavcan::int16_t ErrLogic                   = 1003; ///< Internal logic error
static const uavcan::int16_t ErrUnsupportedFrame        = 1004; ///< Frame not supported (e.g. RTR, CAN FD, etc)
static const uavcan::int16_t ErrMsrInakNotSet           = 1005; ///< INAK bit of the MSR register is not 1
static const uavcan::int16_t ErrMsrInakNotCleared       = 1006; ///< INAK bit of the MSR register is not 0
static const uavcan::int16_t ErrBitRateNotDetected      = 1007; ///< Auto bit rate detection could not be finished
static const uavcan::int16_t ErrFilterNumConfigs        = 1008; ///< Number of filters is more than supported

/**
 * RX queue item.
 * The application shall not use this directly.
 */
struct CanRxItem {
    uavcan::uint64_t utc_usec;
    uavcan::CanFrame frame;
    uavcan::CanIOFlags flags;
    CanRxItem()
        : utc_usec(0)
        , flags(0)
    { }
};

/**
 * Single CAN iface.
 * The application shall not use this directly.
 */
class CanIface : public uavcan::ICanIface, uavcan::Noncopyable
{
    class RxQueue
    {
        CanRxItem *const buf_;
        const uavcan::uint8_t capacity_;
        uavcan::uint8_t in_;
        uavcan::uint8_t out_;
        uavcan::uint8_t len_;
        uavcan::uint32_t overflow_cnt_;

        void registerOverflow();

    public:
        RxQueue(CanRxItem *buf, uavcan::uint8_t capacity)
            : buf_(buf)
            , capacity_(capacity)
            , in_(0)
            , out_(0)
            , len_(0)
            , overflow_cnt_(0)
        { }

        void push(const uavcan::CanFrame &frame, const uint64_t &utc_usec, uavcan::CanIOFlags flags);
        void pop(uavcan::CanFrame &out_frame, uavcan::uint64_t &out_utc_usec, uavcan::CanIOFlags &out_flags);

        void reset();

        unsigned getLength() const { return len_; }

        uavcan::uint32_t getOverflowCount() const { return overflow_cnt_; }
    };

    struct Timings {
        uavcan::uint16_t prescaler;
        uavcan::uint8_t sjw;
        uavcan::uint8_t bs1;
        uavcan::uint8_t bs2;

        Timings()
            : prescaler(0)
            , sjw(0)
            , bs1(0)
            , bs2(0)
        { }
    };

    struct TxItem {
        uavcan::MonotonicTime deadline;
        uavcan::CanFrame frame;
        bool pending;
        bool loopback;
        bool abort_on_error;

        TxItem()
            : pending(false)
            , loopback(false)
            , abort_on_error(false)
        { }
    };

    enum { NumTxMailboxes = 3 };
    enum { NumFilters = 14 };

    static const uavcan::uint32_t TSR_ABRQx[NumTxMailboxes];

    RxQueue rx_queue_;
    bxcan::CanType *const can_;
    uavcan::uint64_t error_cnt_;
    uavcan::uint32_t served_aborts_cnt_;
    BusEvent &update_event_;
    TxItem pending_tx_[NumTxMailboxes];
    uavcan::uint8_t peak_tx_mailbox_index_;
    const uavcan::uint8_t self_index_;
    bool had_activity_;

    int computeTimings(uavcan::uint32_t target_bitrate, Timings &out_timings);

    virtual uavcan::int16_t send(const uavcan::CanFrame &frame, uavcan::MonotonicTime tx_deadline,
                     uavcan::CanIOFlags flags);

    virtual uavcan::int16_t receive(uavcan::CanFrame &out_frame, uavcan::MonotonicTime &out_ts_monotonic,
                    uavcan::UtcTime &out_ts_utc, uavcan::CanIOFlags &out_flags);

    virtual uavcan::int16_t configureFilters(const uavcan::CanFilterConfig *filter_configs,
            uavcan::uint16_t num_configs);

    virtual uavcan::uint16_t getNumFilters() const { return NumFilters; }

    void handleTxMailboxInterrupt(uavcan::uint8_t mailbox_index, bool txok, uavcan::uint64_t utc_usec);

    bool waitMsrINakBitStateChange(bool target_state);

public:
    enum { MaxRxQueueCapacity = 254 };

    enum OperatingMode {
        NormalMode,
        SilentMode
    };

    CanIface(bxcan::CanType *can, BusEvent &update_event, uavcan::uint8_t self_index,
         CanRxItem *rx_queue_buffer, uavcan::uint8_t rx_queue_capacity)
        : rx_queue_(rx_queue_buffer, rx_queue_capacity)
        , can_(can)
        , error_cnt_(0)
        , served_aborts_cnt_(0)
        , update_event_(update_event)
        , peak_tx_mailbox_index_(0)
        , self_index_(self_index)
        , had_activity_(false)
    {
        UAVCAN_ASSERT(self_index_ < UAVCAN_STM32_NUM_IFACES);
    }

    /**
     * Initializes the hardware CAN controller.
     * Assumes:
     *   - Iface clock is enabled
     *   - Iface has been resetted via RCC
     *   - Caller will configure NVIC by itself
     */
    int init(const uavcan::uint32_t bitrate, const OperatingMode mode);

    void handleTxInterrupt(uavcan::uint64_t utc_usec);
    void handleRxInterrupt(uavcan::uint8_t fifo_index, uavcan::uint64_t utc_usec);

    /**
     * This method is used to count errors and abort transmission on error if necessary.
     * This functionality used to be implemented in the SCE interrupt handler, but that approach was
     * generating too much processing overhead, especially on disconnected interfaces.
     *
     * Should be called from RX ISR, TX ISR, and select(); interrupts must be enabled.
     */
    void pollErrorFlagsFromISR();

    void discardTimedOutTxMailboxes(uavcan::MonotonicTime current_time);

    bool canAcceptNewTxFrame(const uavcan::CanFrame &frame) const;
    bool isRxBufferEmpty() const;

    /**
     * Number of RX frames lost due to queue overflow.
     * This is an atomic read, it doesn't require a critical section.
     */
    uavcan::uint32_t getRxQueueOverflowCount() const { return rx_queue_.getOverflowCount(); }

    /**
     * Total number of hardware failures and other kinds of errors (e.g. queue overruns).
     * May increase continuously if the interface is not connected to the bus.
     */
    virtual uavcan::uint64_t getErrorCount() const;

    /**
     * Number of times the driver exercised library's requirement to abort transmission on first error.
     * This is an atomic read, it doesn't require a critical section.
     * See @ref uavcan::CanIOFlagAbortOnError.
     */
    uavcan::uint32_t getVoluntaryTxAbortCount() const { return served_aborts_cnt_; }

    /**
     * Returns the number of frames pending in the RX queue.
     * This is intended for debug use only.
     */
    unsigned getRxQueueLength() const;

    /**
     * Whether this iface had at least one successful IO since the previous call of this method.
     * This is designed for use with iface activity LEDs.
     */
    bool hadActivity();

    /**
     * Peak number of TX mailboxes used concurrently since initialization.
     * Range is [1, 3].
     * Value of 3 suggests that priority inversion could be taking place.
     */
    uavcan::uint8_t getPeakNumTxMailboxesUsed() const { return uavcan::uint8_t(peak_tx_mailbox_index_ + 1); }
};

/**
 * CAN driver, incorporates all available CAN ifaces.
 * Please avoid direct use, prefer @ref CanInitHelper instead.
 */
class CanDriver : public uavcan::ICanDriver, uavcan::Noncopyable
{
    BusEvent update_event_;
    CanIface if0_;
#if UAVCAN_STM32_NUM_IFACES > 1
    CanIface if1_;
#endif

    virtual uavcan::int16_t select(uavcan::CanSelectMasks &inout_masks,
                       const uavcan::CanFrame * (& pending_tx)[uavcan::MaxCanIfaces],
                       uavcan::MonotonicTime blocking_deadline);

    static void initOnce();

public:
    template <unsigned RxQueueCapacity>
    CanDriver(CanRxItem(&rx_queue_storage)[UAVCAN_STM32_NUM_IFACES][RxQueueCapacity])
        : update_event_(*this)
        , if0_(bxcan::Can[0], update_event_, 0, rx_queue_storage[0], RxQueueCapacity)
#if UAVCAN_STM32_NUM_IFACES > 1
        , if1_(bxcan::Can[1], update_event_, 1, rx_queue_storage[1], RxQueueCapacity)
#endif
    {
        uavcan::StaticAssert < (RxQueueCapacity <= CanIface::MaxRxQueueCapacity) >::check();
    }

    /**
     * This function returns select masks indicating which interfaces are available for read/write.
     */
    uavcan::CanSelectMasks makeSelectMasks(const uavcan::CanFrame * (& pending_tx)[uavcan::MaxCanIfaces]) const;

    /**
     * Whether there's at least one interface where receive() would return a frame.
     */
    bool hasReadableInterfaces() const;

    /**
     * Returns zero if OK.
     * Returns negative value if failed (e.g. invalid bitrate).
     */
    int init(const uavcan::uint32_t bitrate, const CanIface::OperatingMode mode);

    virtual CanIface *getIface(uavcan::uint8_t iface_index);

    virtual uavcan::uint8_t getNumIfaces() const { return UAVCAN_STM32_NUM_IFACES; }

    /**
     * Whether at least one iface had at least one successful IO since previous call of this method.
     * This is designed for use with iface activity LEDs.
     */
    bool hadActivity();

    BusEvent &updateEvent() { return update_event_; }
};

/**
 * Helper class.
 * Normally only this class should be used by the application.
 * 145 usec per Extended CAN frame @ 1 Mbps, e.g. 32 RX slots * 145 usec --> 4.6 msec before RX queue overruns.
 */
template <unsigned RxQueueCapacity = 128>
class CanInitHelper
{
    CanRxItem queue_storage_[UAVCAN_STM32_NUM_IFACES][RxQueueCapacity];

public:
    enum { BitRateAutoDetect = 0 };

    CanDriver driver;

    CanInitHelper() :
        driver(queue_storage_)
    { }

    /**
     * This overload simply configures the provided bitrate.
     * Auto bit rate detection will not be performed.
     * Bitrate value must be positive.
     * @return  Negative value on error; non-negative on success. Refer to constants Err*.
     */
    int init(uavcan::uint32_t bitrate)
    {
        return driver.init(bitrate, CanIface::NormalMode);
    }

    /**
     * This function can either initialize the driver at a fixed bit rate, or it can perform
     * automatic bit rate detection. For theory please refer to the CiA application note #801.
     *
     * @param delay_callable    A callable entity that suspends execution for strictly more than one second.
     *                          The callable entity will be invoked without arguments.
     *                          @ref getRecommendedListeningDelay().
     *
     * @param inout_bitrate     Fixed bit rate or zero. Zero invokes the bit rate detection process.
     *                          If auto detection was used, the function will update the argument
     *                          with established bit rate. In case of an error the value will be undefined.
     *
     * @return                  Negative value on error; non-negative on success. Refer to constants Err*.
     */
    template <typename DelayCallable>
    int init(DelayCallable delay_callable, uavcan::uint32_t &inout_bitrate = BitRateAutoDetect)
    {
        if (inout_bitrate > 0) {
            return driver.init(inout_bitrate, CanIface::NormalMode);

        } else {
            static const uavcan::uint32_t StandardBitRates[] = {
                1000000,
                500000,
                250000,
                125000
            };

            for (uavcan::uint8_t br = 0; br < sizeof(StandardBitRates) / sizeof(StandardBitRates[0]); br++) {
                inout_bitrate = StandardBitRates[br];

                const int res = driver.init(inout_bitrate, CanIface::SilentMode);

                delay_callable();

                if (res >= 0) {
                    for (uavcan::uint8_t iface = 0; iface < driver.getNumIfaces(); iface++) {
                        if (!driver.getIface(iface)->isRxBufferEmpty()) {
                            // Re-initializing in normal mode
                            return driver.init(inout_bitrate, CanIface::NormalMode);
                        }
                    }
                }
            }

            return -ErrBitRateNotDetected;
        }
    }

    /**
     * Use this value for listening delay during automatic bit rate detection.
     */
    static uavcan::MonotonicDuration getRecommendedListeningDelay()
    {
        return uavcan::MonotonicDuration::fromMSec(1050);
    }
};

}