circuitpython/ports/atmel-samd/common-hal/busio/I2C.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2016 Scott Shawcroft
 *
 * 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 "py/mperrno.h"
#include "py/runtime.h"

#include "hal/include/hal_gpio.h"
#include "hal/include/hal_i2c_m_sync.h"
#include "hal/include/hpl_i2c_m_sync.h"

#include "peripherals.h"
#include "pins.h"


// Number of times to try to send packet if failed.
#define ATTEMPTS 2

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) {
    Sercom* sercom = NULL;
    uint8_t sercom_index;
    uint32_t sda_pinmux = 0;
    uint32_t scl_pinmux = 0;
    for (int i = 0; i < NUM_SERCOMS_PER_PIN; i++) {
        Sercom* potential_sercom = sda->sercom[i].sercom;
        if (potential_sercom == NULL ||
            potential_sercom->I2CM.CTRLA.bit.ENABLE != 0 ||
            sda->sercom[i].pad != 0) {
            continue;
        }
        sda_pinmux = PINMUX(sda->pin, (i == 0) ? MUX_C : MUX_D);
        for (int j = 0; j < NUM_SERCOMS_PER_PIN; j++) {
            if (potential_sercom == scl->sercom[j].sercom &&
                scl->sercom[j].pad == 1) {
                scl_pinmux = PINMUX(scl->pin, (j == 0) ? MUX_C : MUX_D);
                sercom = potential_sercom;
                sercom_index = scl->sercom[j].index; // 2 for SERCOM2, etc.
                break;
            }
        }
        if (sercom != NULL) {
            break;
        }
    }
    if (sercom == NULL) {
        mp_raise_ValueError("Invalid pins");
    }


    // Set up I2C clocks on sercom.
    samd_peripheral_sercom_clock_init(sercom, sercom_index);

    if (i2c_m_sync_init(&self->i2c_desc, sercom) != ERR_NONE) {
            mp_raise_OSError(MP_EIO);
    }
        
    gpio_set_pin_pull_mode(sda->pin, GPIO_PULL_OFF);
    gpio_set_pin_function(sda->pin, sda_pinmux);

    gpio_set_pin_pull_mode(scl->pin, GPIO_PULL_OFF);
    gpio_set_pin_function(scl->pin, scl_pinmux);

    // clkrate is always 0. baud_rate is in kHz.
    
    // Frequency must be set before the I2C device is enabled.
    if (i2c_m_sync_set_baudrate(&self->i2c_desc, 0, frequency / 1000) != ERR_NONE) {
        mp_raise_ValueError("Unsupported baudrate");
    }

    self->sda_pin = sda->pin;
    self->scl_pin = scl->pin;
    claim_pin(sda);
    claim_pin(scl);

    if (i2c_m_sync_enable(&self->i2c_desc) != ERR_NONE) {
        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 == NO_PIN;
}

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

    i2c_m_sync_disable(&self->i2c_desc);
    i2c_m_sync_deinit(&self->i2c_desc);
    
    reset_pin(self->sda_pin);
    reset_pin(self->scl_pin);
    self->sda_pin = NO_PIN;
    self->scl_pin = NO_PIN;
}

bool common_hal_busio_i2c_probe(busio_i2c_obj_t *self, uint8_t addr) {
    struct io_descriptor *i2c_io;
    i2c_m_sync_get_io_descriptor(&self->i2c_desc, &i2c_io);
    i2c_m_sync_set_slaveaddr(&self->i2c_desc, addr, I2C_M_SEVEN);

    // Write no data when just probing
    return io_write(i2c_io, NULL, 0) == ERR_NONE;
}

bool common_hal_busio_i2c_try_lock(busio_i2c_obj_t *self) {
    bool grabbed_lock = false;
    CRITICAL_SECTION_ENTER()
        if (!self->has_lock) {
            grabbed_lock = true;
            self->has_lock = true;
        }
    CRITICAL_SECTION_LEAVE();
    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;
}

uint8_t common_hal_busio_i2c_write(busio_i2c_obj_t *self, uint16_t addr,
                                   const uint8_t *data, size_t len, bool transmit_stop_bit) {

    uint16_t attempts = ATTEMPTS;
    int32_t status;
    do {
        struct _i2c_m_msg msg;
        msg.addr = addr;
        msg.len = len;
        msg.flags  = transmit_stop_bit ? I2C_M_STOP : 0;
        msg.buffer = (uint8_t *) data;
        status = _i2c_m_sync_transfer(&self->i2c_desc.device, &msg);

        // Give up after ATTEMPTS tries.
        if (--attempts == 0) {
            break;
        }
    } while (status != I2C_OK);
    if (status == I2C_OK) {
        return 0;
    } else if (status == I2C_ERR_BAD_ADDRESS) {
        return MP_ENODEV;
    }
    return MP_EIO;
}

uint8_t common_hal_busio_i2c_read(busio_i2c_obj_t *self, uint16_t addr,
        uint8_t *data, size_t len) {

    uint16_t attempts = ATTEMPTS;
    int32_t status;
    do {
        struct _i2c_m_msg msg;
	msg.addr   = addr;
	msg.len    = len;
	msg.flags  = I2C_M_STOP | I2C_M_RD;
	msg.buffer = data;
        status = _i2c_m_sync_transfer(&self->i2c_desc.device, &msg);

        // Give up after ATTEMPTS tries.
        if (--attempts == 0) {
            break;
        }
    } while (status != I2C_OK);
    if (status == ERR_NONE) {
        return 0;
    } else if (status == I2C_ERR_BAD_ADDRESS) {
        return MP_ENODEV;
    }
    return MP_EIO;
}