machine_i2c.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2016-2018 Damien P. George
 *
 * 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 "py/runtime.h"
#include "py/mphal.h"
#include "py/mperrno.h"
#include "extmod/modmachine.h"
#include "i2c.h"

#if MICROPY_HW_ENABLE_HW_I2C

#define I2C_POLL_DEFAULT_TIMEOUT_US (50000) // 50ms

#if defined(STM32F0) || defined(STM32F4) || defined(STM32F7) || defined(STM32H7) || defined(STM32L1) || defined(STM32L4)

typedef struct _machine_hard_i2c_obj_t {
    mp_obj_base_t base;
    i2c_t *i2c;
    mp_hal_pin_obj_t scl;
    mp_hal_pin_obj_t sda;
} machine_hard_i2c_obj_t;

static const machine_hard_i2c_obj_t machine_hard_i2c_obj[MICROPY_HW_MAX_I2C] = {
    #if defined(MICROPY_HW_I2C1_SCL)
    [0] = {{&machine_i2c_type}, I2C1, MICROPY_HW_I2C1_SCL, MICROPY_HW_I2C1_SDA},
    #endif
    #if defined(MICROPY_HW_I2C2_SCL)
    [1] = {{&machine_i2c_type}, I2C2, MICROPY_HW_I2C2_SCL, MICROPY_HW_I2C2_SDA},
    #endif
    #if defined(MICROPY_HW_I2C3_SCL)
    [2] = {{&machine_i2c_type}, I2C3, MICROPY_HW_I2C3_SCL, MICROPY_HW_I2C3_SDA},
    #endif
    #if defined(MICROPY_HW_I2C4_SCL)
    [3] = {{&machine_i2c_type}, I2C4, MICROPY_HW_I2C4_SCL, MICROPY_HW_I2C4_SDA},
    #endif
};

static void machine_hard_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
    machine_hard_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);

    #if defined(STM32F4) || defined(STM32L1)

    uint32_t freq = self->i2c->CR2 & 0x3f;
    uint32_t ccr = self->i2c->CCR;
    if (ccr & 0x8000) {
        // Fast mode, assume duty cycle of 16/9
        freq = freq * 40000 / (ccr & 0xfff);
    } else {
        // Standard mode
        freq = freq * 500000 / (ccr & 0xfff);
    }

    mp_printf(print, "I2C(%u, scl=%q, sda=%q, freq=%u)",
        self - &machine_hard_i2c_obj[0] + 1,
        mp_hal_pin_name(self->scl), mp_hal_pin_name(self->sda),
        freq);

    #else

    uint32_t timingr = self->i2c->TIMINGR;
    uint32_t presc = timingr >> 28;
    uint32_t sclh = timingr >> 8 & 0xff;
    uint32_t scll = timingr & 0xff;
    uint32_t freq = HAL_RCC_GetPCLK1Freq() / (presc + 1) / (sclh + scll + 2);
    mp_printf(print, "I2C(%u, scl=%q, sda=%q, freq=%u, timingr=0x%08x)",
        self - &machine_hard_i2c_obj[0] + 1,
        mp_hal_pin_name(self->scl), mp_hal_pin_name(self->sda),
        freq, timingr);

    #endif
}

void machine_hard_i2c_init(machine_hard_i2c_obj_t *self, uint32_t freq, uint32_t timeout_us) {
    uint32_t timeout_ms = (timeout_us + 999) / 1000;
    i2c_init(self->i2c, self->scl, self->sda, freq, timeout_ms);
}

int machine_hard_i2c_transfer(mp_obj_base_t *self_in, uint16_t addr, size_t n, mp_machine_i2c_buf_t *bufs, unsigned int flags) {
    machine_hard_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);

    size_t remain_len = 0;
    for (size_t i = 0; i < n; ++i) {
        remain_len += bufs[i].len;
    }

    int ret = i2c_start_addr(self->i2c, flags & MP_MACHINE_I2C_FLAG_READ, addr, remain_len, flags & MP_MACHINE_I2C_FLAG_STOP);
    if (ret < 0) {
        return ret;
    }

    int num_acks = 0; // only valid for write; for read it'll be 0
    for (; n--; ++bufs) {
        remain_len -= bufs->len;
        if (flags & MP_MACHINE_I2C_FLAG_READ) {
            ret = i2c_read(self->i2c, bufs->buf, bufs->len, remain_len);
        } else {
            ret = i2c_write(self->i2c, bufs->buf, bufs->len, remain_len);
        }
        if (ret < 0) {
            return ret;
        }
        num_acks += ret;
    }

    return num_acks;
}

#else

// No hardware I2C driver for this MCU so use the software implementation

typedef mp_machine_soft_i2c_obj_t machine_hard_i2c_obj_t;

static machine_hard_i2c_obj_t machine_hard_i2c_obj[MICROPY_HW_MAX_I2C] = {
    #if defined(MICROPY_HW_I2C1_SCL)
    [0] = {{&machine_i2c_type}, 1, I2C_POLL_DEFAULT_TIMEOUT_US, MICROPY_HW_I2C1_SCL, MICROPY_HW_I2C1_SDA},
    #endif
    #if defined(MICROPY_HW_I2C2_SCL)
    [1] = {{&machine_i2c_type}, 1, I2C_POLL_DEFAULT_TIMEOUT_US, MICROPY_HW_I2C2_SCL, MICROPY_HW_I2C2_SDA},
    #endif
    #if defined(MICROPY_HW_I2C3_SCL)
    [2] = {{&machine_i2c_type}, 1, I2C_POLL_DEFAULT_TIMEOUT_US, MICROPY_HW_I2C3_SCL, MICROPY_HW_I2C3_SDA},
    #endif
    #if defined(MICROPY_HW_I2C4_SCL)
    [3] = {{&machine_i2c_type}, 1, I2C_POLL_DEFAULT_TIMEOUT_US, MICROPY_HW_I2C4_SCL, MICROPY_HW_I2C4_SDA},
    #endif
};

static void machine_hard_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
    machine_hard_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
    mp_printf(print, "I2C(%u, scl=%q, sda=%q, freq=%u, timeout=%u)",
        self - &machine_hard_i2c_obj[0] + 1,
        self->scl->name, self->sda->name, 500000 / self->us_delay, self->us_timeout);
}

static void machine_hard_i2c_init(machine_hard_i2c_obj_t *self, uint32_t freq, uint32_t timeout) {
    // set parameters
    if (freq >= 1000000) {
        // allow fastest possible bit-bang rate
        self->us_delay = 0;
    } else {
        self->us_delay = 500000 / freq;
        if (self->us_delay == 0) {
            self->us_delay = 1;
        }
    }

    self->us_timeout = timeout;

    // init pins
    mp_hal_pin_open_drain(self->scl);
    mp_hal_pin_open_drain(self->sda);
}

#define machine_hard_i2c_transfer mp_machine_soft_i2c_transfer

#endif

/******************************************************************************/
/* MicroPython bindings for machine API                                       */

#if defined(STM32F0) || defined(STM32F7) || defined(STM32H7) || defined(STM32L4)
#define MACHINE_I2C_TIMINGR (1)
#else
#define MACHINE_I2C_TIMINGR (0)
#endif

mp_obj_t machine_hard_i2c_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
    MP_MACHINE_I2C_CHECK_FOR_LEGACY_SOFTI2C_CONSTRUCTION(n_args, n_kw, all_args);

    // parse args
    enum { ARG_id, ARG_scl, ARG_sda, ARG_freq, ARG_timeout, ARG_timingr };
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_id, MP_ARG_REQUIRED | MP_ARG_OBJ },
        { MP_QSTR_scl, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
        { MP_QSTR_sda, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
        { MP_QSTR_freq, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 400000} },
        { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = I2C_POLL_DEFAULT_TIMEOUT_US} },
        #if MACHINE_I2C_TIMINGR
        { MP_QSTR_timingr, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
        #endif
    };
    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);

    // get static peripheral object
    int i2c_id = i2c_find_peripheral(args[ARG_id].u_obj);
    machine_hard_i2c_obj_t *self = (machine_hard_i2c_obj_t *)&machine_hard_i2c_obj[i2c_id - 1];

    // here we would check the scl/sda pins and configure them, but it's not implemented
    if (args[ARG_scl].u_obj != MP_OBJ_NULL || args[ARG_sda].u_obj != MP_OBJ_NULL) {
        mp_raise_ValueError(MP_ERROR_TEXT("explicit choice of scl/sda is not implemented"));
    }

    // initialise the I2C peripheral
    machine_hard_i2c_init(self, args[ARG_freq].u_int, args[ARG_timeout].u_int);

    #if MACHINE_I2C_TIMINGR
    // If given, explicitly set the TIMINGR value
    if (args[ARG_timingr].u_obj != mp_const_none) {
        self->i2c->TIMINGR = mp_obj_get_int_truncated(args[ARG_timingr].u_obj);
    }
    #endif

    return MP_OBJ_FROM_PTR(self);
}

static const mp_machine_i2c_p_t machine_hard_i2c_p = {
    .transfer = machine_hard_i2c_transfer,
};

MP_DEFINE_CONST_OBJ_TYPE(
    machine_i2c_type,
    MP_QSTR_I2C,
    MP_TYPE_FLAG_NONE,
    make_new, machine_hard_i2c_make_new,
    print, machine_hard_i2c_print,
    protocol, &machine_hard_i2c_p,
    locals_dict, &mp_machine_i2c_locals_dict
    );

#endif // MICROPY_HW_ENABLE_HW_I2C