circuitpython/ports/nrf/common-hal/busio/I2C.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2019 Dan Halbert for Adafruit Industries
 * Copyright (c) 2018 Artur Pacholec
 * Copyright (c) 2017 hathach
 * Copyright (c) 2016 Sandeep Mistry All right reserved.
 *
 * 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.
 */

#include "shared-bindings/busio/I2C.h"
#include "shared-bindings/microcontroller/__init__.h"
#include "shared-bindings/microcontroller/Pin.h"
#include "py/mperrno.h"
#include "py/runtime.h"
#include "supervisor/shared/translate/translate.h"

#include "nrfx_twim.h"
#include "nrfx_spim.h"
#include "nrf_gpio.h"

// all TWI instances have the same max size
// 16 bits for 840, 10 bits for 810, 8 bits for 832
#define I2C_MAX_XFER_LEN         ((1UL << TWIM0_EASYDMA_MAXCNT_SIZE) - 1)

STATIC twim_peripheral_t twim_peripherals[] = {
    #if NRFX_CHECK(NRFX_TWIM0_ENABLED)
    // SPIM0 and TWIM0 share an address.
    { .twim = NRFX_TWIM_INSTANCE(0),
      .in_use = false},
    #endif
    #if NRFX_CHECK(NRFX_TWIM1_ENABLED)
    // SPIM1 and TWIM1 share an address.
    { .twim = NRFX_TWIM_INSTANCE(1),
      .in_use = false},
    #endif
};

STATIC bool never_reset[MP_ARRAY_SIZE(twim_peripherals)];

void i2c_reset(void) {
    for (size_t i = 0; i < MP_ARRAY_SIZE(twim_peripherals); i++) {
        if (never_reset[i]) {
            continue;
        }
        nrfx_twim_uninit(&twim_peripherals[i].twim);
        twim_peripherals[i].in_use = false;
    }
}

void common_hal_busio_i2c_never_reset(busio_i2c_obj_t *self) {
    for (size_t i = 0; i < MP_ARRAY_SIZE(twim_peripherals); i++) {
        if (self->twim_peripheral == &twim_peripherals[i]) {
            never_reset[i] = true;

            never_reset_pin_number(self->scl_pin_number);
            never_reset_pin_number(self->sda_pin_number);
            break;
        }
    }
}

static bool _bus_is_sane(uint32_t scl_pin, uint32_t sda_pin) {
    #if CIRCUITPY_REQUIRE_I2C_PULLUPS
    nrf_gpio_cfg_input(scl_pin, NRF_GPIO_PIN_PULLDOWN);
    nrf_gpio_cfg_input(sda_pin, NRF_GPIO_PIN_PULLDOWN);

    common_hal_mcu_delay_us(10);

    nrf_gpio_cfg_input(scl_pin, NRF_GPIO_PIN_NOPULL);
    nrf_gpio_cfg_input(sda_pin, NRF_GPIO_PIN_NOPULL);

    // We must pull up within 3us to achieve 400khz.
    common_hal_mcu_delay_us(3);
    if (!nrf_gpio_pin_read(sda_pin) || !nrf_gpio_pin_read(scl_pin)) {
        return false;
    } else {
        return true;
    }
    #else
    return true;
    #endif
}

static nrfx_err_t _safe_twim_enable(busio_i2c_obj_t *self) {
    // check to see if bus is in sensible state before enabling twim
    nrfx_err_t recover_result;

    if (!_bus_is_sane(self->scl_pin_number, self->sda_pin_number)) {
        // bus not in a sane state - try to recover
        recover_result = nrfx_twim_bus_recover(self->scl_pin_number, self->sda_pin_number);
        if (NRFX_SUCCESS != recover_result) {
            // return error message if unable to recover the bus
            return recover_result;
        }
    }

    nrfx_twim_enable(&self->twim_peripheral->twim);
    return NRFX_SUCCESS;
}

static uint8_t twi_error_to_mp(const nrfx_err_t err) {
    switch (err) {
        case NRFX_ERROR_DRV_TWI_ERR_ANACK:
            return MP_ENODEV;
        case NRFX_ERROR_BUSY:
            return MP_EBUSY;
        case NRFX_SUCCESS:
            return 0;
        case NRFX_ERROR_DRV_TWI_ERR_DNACK:
        case NRFX_ERROR_INVALID_ADDR:
        case NRFX_ERROR_INTERNAL:
        default:
            return MP_EIO;
    }
}

void common_hal_busio_i2c_construct(busio_i2c_obj_t *self, const mcu_pin_obj_t *scl, const mcu_pin_obj_t *sda, uint32_t frequency, uint32_t timeout) {
    if (scl->number == sda->number) {
        raise_ValueError_invalid_pins();
    }

    // Find a free instance.
    self->twim_peripheral = NULL;
    for (size_t i = 0; i < MP_ARRAY_SIZE(twim_peripherals); i++) {
        if (!twim_peripherals[i].in_use) {
            self->twim_peripheral = &twim_peripherals[i];
            // Mark it as in_use later after other validation is finished.
            break;
        }
    }

    if (self->twim_peripheral == NULL) {
        mp_raise_ValueError(translate("All I2C peripherals are in use"));
    }

    // check bus is in a sane state
    if (!_bus_is_sane(scl->number,sda->number)) {
        reset_pin_number(sda->number);
        reset_pin_number(scl->number);
        mp_raise_RuntimeError(translate("No pull up found on SDA or SCL; check your wiring"));
    }

    nrfx_twim_config_t config = NRFX_TWIM_DEFAULT_CONFIG(scl->number, sda->number);

    #if defined(TWIM_FREQUENCY_FREQUENCY_K1000)
    if (frequency >= 1000000) {
        config.frequency = NRF_TWIM_FREQ_1000K;
    } else
    #endif
    if (frequency >= 400000) {
        config.frequency = NRF_TWIM_FREQ_400K;
    } else if (frequency >= 250000) {
        config.frequency = NRF_TWIM_FREQ_250K;
    } else {
        config.frequency = NRF_TWIM_FREQ_100K;
    }

    self->scl_pin_number = scl->number;
    self->sda_pin_number = sda->number;
    claim_pin(sda);
    claim_pin(scl);

    // About to init. If we fail after this point, common_hal_busio_i2c_deinit() will set in_use to false.
    self->twim_peripheral->in_use = true;
    nrfx_err_t err = nrfx_twim_init(&self->twim_peripheral->twim, &config, NULL, NULL);
    if (err != NRFX_SUCCESS) {
        common_hal_busio_i2c_deinit(self);
        mp_raise_OSError(MP_EIO);
    }

}

bool common_hal_busio_i2c_deinited(busio_i2c_obj_t *self) {
    return self->sda_pin_number == NO_PIN;
}

void common_hal_busio_i2c_deinit(busio_i2c_obj_t *self) {
    if (common_hal_busio_i2c_deinited(self)) {
        return;
    }

    nrfx_twim_uninit(&self->twim_peripheral->twim);

    reset_pin_number(self->sda_pin_number);
    reset_pin_number(self->scl_pin_number);
    self->sda_pin_number = NO_PIN;
    self->scl_pin_number = NO_PIN;

    self->twim_peripheral->in_use = false;
}

// nrfx_twim_tx doesn't support 0-length data so we fall back to the hal API
bool common_hal_busio_i2c_probe(busio_i2c_obj_t *self, uint8_t addr) {
    NRF_TWIM_Type *reg = self->twim_peripheral->twim.p_twim;
    bool found = true;

    if (NRFX_SUCCESS != _safe_twim_enable(self)) {
        return false;
    }

    nrf_twim_address_set(reg, addr);
    nrf_twim_tx_buffer_set(reg, NULL, 0);

    nrf_twim_task_trigger(reg, NRF_TWIM_TASK_RESUME);

    nrf_twim_task_trigger(reg, NRF_TWIM_TASK_STARTTX);
    while (nrf_twim_event_check(reg, NRF_TWIM_EVENT_TXSTARTED) == 0 &&
           nrf_twim_event_check(reg, NRF_TWIM_EVENT_ERROR) == 0) {
        ;
    }
    nrf_twim_event_clear(reg, NRF_TWIM_EVENT_TXSTARTED);

    nrf_twim_task_trigger(reg, NRF_TWIM_TASK_STOP);
    while (nrf_twim_event_check(reg, NRF_TWIM_EVENT_STOPPED) == 0) {
        ;
    }
    nrf_twim_event_clear(reg, NRF_TWIM_EVENT_STOPPED);

    if (nrf_twim_event_check(reg, NRF_TWIM_EVENT_ERROR)) {
        nrf_twim_event_clear(reg, NRF_TWIM_EVENT_ERROR);

        nrf_twim_errorsrc_get_and_clear(reg);
        found = false;
    }

    nrfx_twim_disable(&self->twim_peripheral->twim);

    return found;
}

bool common_hal_busio_i2c_try_lock(busio_i2c_obj_t *self) {
    bool grabbed_lock = false;
    // NRFX_CRITICAL_SECTION_ENTER();
    if (!self->has_lock) {
        grabbed_lock = true;
        self->has_lock = true;
    }
    // NRFX_CRITICAL_SECTION_EXIT();
    return grabbed_lock;
}

bool common_hal_busio_i2c_has_lock(busio_i2c_obj_t *self) {
    return self->has_lock;
}

void common_hal_busio_i2c_unlock(busio_i2c_obj_t *self) {
    self->has_lock = false;
}

STATIC uint8_t _common_hal_busio_i2c_write(busio_i2c_obj_t *self, uint16_t addr, const uint8_t *data, size_t len, bool stopBit) {
    if (len == 0) {
        return common_hal_busio_i2c_probe(self, addr) ? 0 : MP_ENODEV;
    }

    nrfx_err_t err = NRFX_SUCCESS;

    err = _safe_twim_enable(self);
    if (NRFX_SUCCESS != err) {
        return twi_error_to_mp(err);
    }

    // break into MAX_XFER_LEN transaction
    while (len) {
        const size_t xact_len = MIN(len, I2C_MAX_XFER_LEN);
        nrfx_twim_xfer_desc_t xfer_desc = NRFX_TWIM_XFER_DESC_TX(addr, (uint8_t *)data, xact_len);
        uint32_t const flags = (stopBit ? 0 : NRFX_TWIM_FLAG_TX_NO_STOP);

        if (NRFX_SUCCESS != (err = nrfx_twim_xfer(&self->twim_peripheral->twim, &xfer_desc, flags))) {
            break;
        }

        len -= xact_len;
        data += xact_len;
    }

    nrfx_twim_disable(&self->twim_peripheral->twim);

    return twi_error_to_mp(err);
}

uint8_t common_hal_busio_i2c_write(busio_i2c_obj_t *self, uint16_t addr, const uint8_t *data, size_t len) {
    return _common_hal_busio_i2c_write(self, addr, data, len, true);
}

uint8_t common_hal_busio_i2c_read(busio_i2c_obj_t *self, uint16_t addr, uint8_t *data, size_t len) {
    if (len == 0) {
        return 0;
    }

    nrfx_err_t err = NRFX_SUCCESS;

    err = _safe_twim_enable(self);
    if (NRFX_SUCCESS != err) {
        return twi_error_to_mp(err);
    }

    // break into MAX_XFER_LEN transaction
    while (len) {
        const size_t xact_len = MIN(len, I2C_MAX_XFER_LEN);
        nrfx_twim_xfer_desc_t xfer_desc = NRFX_TWIM_XFER_DESC_RX(addr, data, xact_len);

        if (NRFX_SUCCESS != (err = nrfx_twim_xfer(&self->twim_peripheral->twim, &xfer_desc, 0))) {
            break;
        }

        len -= xact_len;
        data += xact_len;
    }

    nrfx_twim_disable(&self->twim_peripheral->twim);

    return twi_error_to_mp(err);
}

uint8_t common_hal_busio_i2c_write_read(busio_i2c_obj_t *self, uint16_t addr,
    uint8_t *out_data, size_t out_len, uint8_t *in_data, size_t in_len) {
    uint8_t result = _common_hal_busio_i2c_write(self, addr, out_data, out_len, false);
    if (result != 0) {
        return result;
    }

    return common_hal_busio_i2c_read(self, addr, in_data, in_len);
}