mc33972.cpp

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/*
 * mc33972.cpp
 * looks like chip is not very available these days TODO https://github.com/rusefi/rusefi/issues/5733
 *
 * Multiple Switch Detection Interface with Suppressed Wake-up
 *
 * TODO: add analog muxing part of the driver
 *
 * The 33972 Multiple Switch Detection Interface with suppressed
 * wake-up is designed to detect the closing and opening of up to 22
 * switch contacts: 14 switch to ground detection and 8 switch to 
 * ground or battery detection, 
 *
 * SPI protocol 3.3/5.0V
 *
 * @date Apr 07, 2019
 * @author Andrey Gusakov <dron0gus@gmail.com>, (c) 2019
 */
 
#include "global.h"
#include "gpio/gpio_ext.h"
#include "gpio/mc33972.h"
 
#if (BOARD_MC33972_COUNT > 0)
 
/*
 * TODO list:
 * - add irq support with fallback to polling mode (now polling mode only)
 */
 
/*==========================================================================*/
/* Driver local definitions.                                                */
/*==========================================================================*/
 
#define DRIVER_NAME             "mc33972"
 
typedef enum {
    MC33972_DISABLED = 0,
    MC33972_WAIT_INIT,
    MC33972_READY,
    MC33972_FAILED
} mc33972_drv_state;
 
#define SP_BANK                     0
#define SG_BANK                     1
 
/* all commands and reply data are 24 bit */
#define CMD(cmd, data)              (((cmd) << 16) | ((data) << 0))
 
#define CMD_STATUS                  CMD(0x00,       0x00)
#define CMD_SETTINGS(mask)          CMD(0x01,       (mask))
#define CMD_WAKEUPEN(i, mask)       CMD(0x02 + (i), (mask))
#define CMD_METALLIC(i, mask)       CMD(0x04 + (i), (mask))
#define CMD_ANALOG(curr, ch)        CMD(0x06,       (((curr) & 0x3) << 5) | (((ch) & 0x1f) << 0))
#define CMD_WETTING_TMR(i, mask)    CMD(0x07 + (i), (mask))
#define CMD_TRI_STATE(i, mask)      CMD(0x09 + (i), (mask))
#define CMD_CALIB                   CMD(0x0b,       0x00)
#define CMD_SLEEP(int_t, scan_t)    CMD(0x0c,       (((int_t) & 0x7) << 3) | (((scan_t) & 0x7) << 0))
#define CMD_RST                     CMD(0x7f,       0x00)
 
/* all switch to battery or ground pins mask */
#define SP_PINS_MASK                0x00ff
#define SP_PINS_EXTRACT(pins)       (((pins) >> 14) & SP_PINS_MASK)
/* all switch-to-ground inputs mask */
#define SG_PINS_MASK                0x3fff
#define SG_PINS_EXTRACT(pins)       (((pins) >>  0) & SG_PINS_MASK)
 
/* reply is allways same 24 status bits */
#define FLAG_THERM                  (1 << 23)
#define FLAG_INT                    (1 << 22)
/* from LSB to MSB: SG0..SG13, SP0..SP7 */
#define PIN_MASK(pin)               (BIT(pin))
 
/*==========================================================================*/
/* Driver exported variables.                                               */
/*==========================================================================*/
 
/*==========================================================================*/
/* Driver local variables and types.                                        */
/*==========================================================================*/
 
/* Driver */
struct Mc33972 : public GpioChip {
    int init() override;
    int deinit() override;
 
    // These functions need not be implemented if not supported by the particular chip.
    /* pin argument is pin number within gpio chip, not a global number */
    int setPadMode(size_t pin, iomode_t mode) override;
    int readPad(size_t pin) override;
    brain_pin_diag_e getDiag(size_t pin) override;
 
    // internal functions
 
    int chip_init();
    int update_pullups();
    int update_status();
 
    void wake_driver();
 
    int spi_w(uint32_t tx);
 
    int comm_test();
 
 
 
    const struct mc33972_config *cfg;
 
    /* thread stuff */
    thread_t                    *thread;
    THD_WORKING_AREA(thread_wa, 256);
    semaphore_t                 wake;
 
    /* last input state from chip */
    uint32_t                    i_state;
    /* currently selected analog input */
    uint8_t                     analog_ch;
    /* enabled inputs */
    uint32_t                    en_pins;
 
    mc33972_drv_state           drv_state;
};
 
static Mc33972 chips[BOARD_MC33972_COUNT];
 
/*==========================================================================*/
/* Driver local functions.                                                  */
/*==========================================================================*/
 
/**
 * @brief MC33972 send cmd routine.
 * @details Sends 24 bits of data. CS asserted before and released
 *  after transaction. Chip allways reply with input state + 2 bits
 *  of diagnostic. This routine save it to chip->i_state
 */
 
int Mc33972::spi_w(uint32_t tx)
{
    int i;
    uint8_t rxb[3];
    uint8_t txb[3];
    SPIDriver *spi = cfg->spi_bus;
 
    txb[0] = (tx >> 16) & 0xff;
    txb[1] = (tx >>  8) & 0xff;
    txb[2] = (tx >>  0) & 0xff;
    /* Acquire ownership of the bus. */
    spiAcquireBus(spi);
    /* Setup transfer parameters. */
    spiStart(spi, &cfg->spi_config);
    /* Slave Select assertion. */
    spiSelect(spi);
    /* Atomic transfer operations. */
    for (i = 0; i < 3; i++)
        rxb[i] = spiPolledExchange(spi, txb[i]);
    /* Slave Select de-assertion. */
    spiUnselect(spi);
    /* Ownership release. */
    spiReleaseBus(spi);
 
    /* save received data */
    i_state = (rxb[0] << 16) | (rxb[1] << 8) | (rxb[2] << 0);
 
    /* no errors for now */
    return 0;
}
 
/**
 * @brief MC33972 update status
 * @details Chip reply with input data and two bits of diag
 */
 
int Mc33972::update_status()
{
    return spi_w(CMD_STATUS);
}
 
int Mc33972::update_pullups()
{
    int ret;
 
    /* enable tri-state for all unused pins */
    ret = spi_w(CMD_TRI_STATE(SP_BANK, SP_PINS_EXTRACT(~en_pins)));
    if (ret)
        return ret;
    ret = spi_w(CMD_TRI_STATE(SG_BANK, SG_PINS_EXTRACT(~en_pins)));
 
    return ret;
}
 
int Mc33972::comm_test()
{
    int ret;
 
    /* After an input has been selected as the analog,
     * the corresponding bit in the next SO data stream
     * will be logic [0] */
 
    /* go throught all inputs, read inputs status and
     * check that muxed input bit is zero */
    for (int i = 0; i < MC33972_INPUTS; i++) {
        /* indexed starting from 1 */
        ret = spi_w(CMD_ANALOG(0, i + 1));
        if (ret)
            return ret;
        ret = update_status();
        if (ret)
            return ret;
 
        if (i_state & PIN_MASK(i))
            return -1;
    }
 
    return 0;
}
 
/**
 * @brief MC33972 chip init.
 * @details There is no way to check communication.
 *  Performs reset.
 */
 
int Mc33972::chip_init()
{
    int ret;
 
    /* reset first */
    ret = spi_w(CMD_RST);
    if (ret)
        return ret;
 
    /* is it enought? */
    chThdSleepMilliseconds(3);
 
    /*
     * Default settings from Power-ON Reset via V PWR or the
     * Reset Command are as follows:
     * * Programmable switch - set to switch to battery
     * * All inputs set as wake-up
     * * Wetting current on (16 mA)
     * * Wetting current timer on (20 ms)
     * * All inputs tri-state
     * * Analog select 00000 (no input channel selected)
     */
 
    /* check communication */
    ret = comm_test();
    if (ret)
        return ret;
 
    /* disable tri-state for used pins only */
    ret = update_pullups();
    if (ret)
        return ret;
 
    /* Set wetting current to 2 mA */
    ret = spi_w(CMD_METALLIC(SP_BANK, 0));
    if (ret)
        return ret;
    ret = spi_w(CMD_METALLIC(SG_BANK, 0));
    if (ret)
        return ret;
 
    return 0;
}
 
/**
 * @brief MC33972 chip driver wakeup.
 * @details Wake up driver. Will cause input and diagnostic
 *  update
 */
void Mc33972::wake_driver()
{
    /* Entering a reentrant critical zone */
    chibios_rt::CriticalSectionLocker csl;
 
    chSemSignalI(&wake);
    if (!port_is_isr_context()) {
        /**
         * chSemSignalI above requires rescheduling
         * interrupt handlers have implicit rescheduling
         */
        chSchRescheduleS();
    }
}
 
/*==========================================================================*/
/* Driver thread.                                                           */
/*==========================================================================*/
 
static THD_FUNCTION(mc33972_driver_thread, p)
{
    int ret;
    Mc33972 *chip = reinterpret_cast<Mc33972*>(p);
 
    chRegSetThreadName(DRIVER_NAME);
 
    /* repeat init until success */
    do {
        ret = chip->chip_init();
        if (ret) {
            chThdSleepMilliseconds(1000);
            continue;
        }
        /* else */
        chip->drv_state = MC33972_READY;
    } while (chip->drv_state != MC33972_READY);
 
    while(1) {
        msg_t msg = chSemWaitTimeout(&chip->wake, TIME_MS2I(MC33972_POLL_INTERVAL_MS));
 
        if ((chip->cfg == NULL) ||
            (chip->drv_state == MC33972_DISABLED) ||
            (chip->drv_state == MC33972_FAILED))
            continue;
 
        if (msg == MSG_TIMEOUT) {
            /* only input state update */
            ret = chip->update_status();
        } else {
            /* someone waked thread and asks us to update pin config */
            /* inputs state is also read */
            ret = chip->update_pullups();
        }
 
        if (ret) {
            /* set state to MC33972_FAILED? */
        }
    }
}
 
/*==========================================================================*/
/* Driver interrupt handlers.                                               */
/*==========================================================================*/
 
/* TODO: add IRQ support */
 
/*==========================================================================*/
/* Driver exported functions.                                               */
/*==========================================================================*/
 
int Mc33972::setPadMode(size_t pin, iomode_t mode) {
    if (pin >= MC33972_INPUTS)
        return -1;
 
    /* currently driver doesn't know how to hanlde different modes */
    (void)mode;
 
    /* NOTE: currently this driver supports only input mode...
     * while chip can output by manipulating with pull-up and
     * pull-down modes....
     * if this function is called for pin, that means someone
     * wants to read this pin and we can enable pull-up
     * Also pull down is not supported yet */
    en_pins |= PIN_MASK(pin);
 
    /* ask for reinit */
    wake_driver();
 
    return 0;
}
 
int Mc33972::readPad(size_t pin) {
    if (pin >= MC33972_INPUTS)
        return -1;
 
    /* convert to some common enum? */
    return !!(i_state & PIN_MASK(pin));
}
 
brain_pin_diag_e Mc33972::getDiag(size_t pin) {
    brain_pin_diag_e diag = PIN_OK;
 
    if (pin >= MC33972_INPUTS)
        return PIN_UNKNOWN;
 
    /* one diag bit for all pins */
    if (i_state & FLAG_THERM)
        diag = PIN_DRIVER_OVERTEMP;
 
    return diag;
}
 
int Mc33972::init()
{
    /* no pins enabled yet */
    en_pins = 0x0000;
 
    /* init semaphore */
    chSemObjectInit(&wake, 0);
 
    /* start thread */
    thread = chThdCreateStatic(thread_wa, sizeof(thread_wa),
                                     PRIO_GPIOCHIP, mc33972_driver_thread, this);
 
    return 0;
}
 
int Mc33972::deinit()
{
    /* TODO: disable pulls for all pins? */
 
    /* stop thread */
    chThdTerminate(thread);
 
    return 0;
}
 
/**
 * @brief MC33972 driver add.
 * @details Checks for valid config
 */
 
int mc33972_add(brain_pin_e base, unsigned int index, const struct mc33972_config *cfg)
{
    /* no config or no such chip */
    if ((!cfg) || (!cfg->spi_bus) || (index >= BOARD_MC33972_COUNT))
        return -1;
 
    /* check for valid cs.
     * TODO: remove this check? CS can be driven by SPI */
    if (!cfg->spi_config.ssport) {
        return -1;
    }
 
    Mc33972& chip = chips[index];
 
    /* already initted? */
    if (chip.cfg != NULL)
        return -1;
 
    chip.cfg = cfg;
    chip.i_state = 0;
    chip.drv_state = MC33972_WAIT_INIT;
 
    /* register, return gpio chip base */
    return gpiochip_register(base, DRIVER_NAME, chip, MC33972_INPUTS);
}
 
#else /* BOARD_MC33972_COUNT > 0 */
 
int mc33972_add(brain_pin_e base, unsigned int index, const struct mc33972_config *cfg)
{
    (void)base; (void)index; (void)cfg;
 
    return -1;
}
 
#endif /* BOARD_MC33972_COUNT */