circuitpython/shared-bindings/bitbangio/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.
 */

// This file contains all of the Python API definitions for the
// bitbangio.I2C class.

#include "shared-bindings/bitbangio/I2C.h"
#include "shared-bindings/microcontroller/Pin.h"
#include "shared-bindings/util.h"

#include "shared/runtime/buffer_helper.h"
#include "shared/runtime/context_manager_helpers.h"
#include "py/binary.h"
#include "py/mperrno.h"
#include "py/runtime.h"

//| class I2C:
//|     """Two wire serial protocol"""
//|
//|     def __init__(
//|         self,
//|         scl: microcontroller.Pin,
//|         sda: microcontroller.Pin,
//|         *,
//|         frequency: int = 400000,
//|         timeout: int = 255
//|     ) -> None:
//|         """I2C is a two-wire protocol for communicating between devices.  At the
//|         physical level it consists of 2 wires: SCL and SDA, the clock and data
//|         lines respectively.
//|
//|         .. seealso:: Using this class directly requires careful lock management.
//|             Instead, use :class:`~adafruit_bus_device.i2c_device.I2CDevice` to
//|             manage locks.
//|
//|         .. seealso:: Using this class to directly read registers requires manual
//|             bit unpacking. Instead, use an existing driver or make one with
//|             :ref:`Register <register-module-reference>` data descriptors.
//|
//|         :param ~microcontroller.Pin scl: The clock pin
//|         :param ~microcontroller.Pin sda: The data pin
//|         :param int frequency: The clock frequency of the bus
//|         :param int timeout: The maximum clock stretching timeout in microseconds"""
//|         ...
STATIC mp_obj_t bitbangio_i2c_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
    enum { ARG_scl, ARG_sda, ARG_frequency, ARG_timeout };
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_scl, MP_ARG_REQUIRED | MP_ARG_OBJ },
        { MP_QSTR_sda, MP_ARG_REQUIRED | MP_ARG_OBJ },
        { MP_QSTR_frequency, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 400000} },
        { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 255} },
    };
    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);

    const mcu_pin_obj_t *scl = validate_obj_is_free_pin(args[ARG_scl].u_obj, MP_QSTR_scl);
    const mcu_pin_obj_t *sda = validate_obj_is_free_pin(args[ARG_sda].u_obj, MP_QSTR_sda);

    bitbangio_i2c_obj_t *self = mp_obj_malloc(bitbangio_i2c_obj_t, &bitbangio_i2c_type);
    shared_module_bitbangio_i2c_construct(self, scl, sda, args[ARG_frequency].u_int, args[ARG_timeout].u_int);
    return (mp_obj_t)self;
}

//|     def deinit(self) -> None:
//|         """Releases control of the underlying hardware so other classes can use it."""
//|         ...
STATIC mp_obj_t bitbangio_i2c_obj_deinit(mp_obj_t self_in) {
    bitbangio_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
    shared_module_bitbangio_i2c_deinit(self);
    return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(bitbangio_i2c_deinit_obj, bitbangio_i2c_obj_deinit);

STATIC void check_for_deinit(bitbangio_i2c_obj_t *self) {
    if (shared_module_bitbangio_i2c_deinited(self)) {
        raise_deinited_error();
    }
}

//|     def __enter__(self) -> I2C:
//|         """No-op used in Context Managers."""
//|         ...
//  Provided by context manager helper.

//|     def __exit__(self) -> None:
//|         """Automatically deinitializes the hardware on context exit. See
//|         :ref:`lifetime-and-contextmanagers` for more info."""
//|         ...
STATIC mp_obj_t bitbangio_i2c_obj___exit__(size_t n_args, const mp_obj_t *args) {
    (void)n_args;
    shared_module_bitbangio_i2c_deinit(args[0]);
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bitbangio_i2c_obj___exit___obj, 4, 4, bitbangio_i2c_obj___exit__);

static void check_lock(bitbangio_i2c_obj_t *self) {
    if (!shared_module_bitbangio_i2c_has_lock(self)) {
        mp_raise_RuntimeError(MP_ERROR_TEXT("Function requires lock"));
    }
}

//|     def scan(self) -> List[int]:
//|         """Scan all I2C addresses between 0x08 and 0x77 inclusive and return a list of
//|         those that respond.  A device responds if it pulls the SDA line low after
//|         its address (including a read bit) is sent on the bus."""
//|         ...
STATIC mp_obj_t bitbangio_i2c_scan(mp_obj_t self_in) {
    bitbangio_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
    check_for_deinit(self);
    check_lock(self);
    mp_obj_t list = mp_obj_new_list(0, NULL);
    // 7-bit addresses 0b0000xxx and 0b1111xxx are reserved
    for (int addr = 0x08; addr < 0x78; ++addr) {
        bool success = shared_module_bitbangio_i2c_probe(self, addr);
        if (success) {
            mp_obj_list_append(list, MP_OBJ_NEW_SMALL_INT(addr));
        }
    }
    return list;
}
MP_DEFINE_CONST_FUN_OBJ_1(bitbangio_i2c_scan_obj, bitbangio_i2c_scan);

//|     def try_lock(self) -> bool:
//|         """Attempts to grab the I2C lock. Returns True on success."""
//|         ...
STATIC mp_obj_t bitbangio_i2c_obj_try_lock(mp_obj_t self_in) {
    bitbangio_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
    check_for_deinit(self);
    return mp_obj_new_bool(shared_module_bitbangio_i2c_try_lock(self));
}
MP_DEFINE_CONST_FUN_OBJ_1(bitbangio_i2c_try_lock_obj, bitbangio_i2c_obj_try_lock);

//|     def unlock(self) -> None:
//|         """Releases the I2C lock."""
//|         ...
STATIC mp_obj_t bitbangio_i2c_obj_unlock(mp_obj_t self_in) {
    bitbangio_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
    check_for_deinit(self);
    shared_module_bitbangio_i2c_unlock(self);
    return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(bitbangio_i2c_unlock_obj, bitbangio_i2c_obj_unlock);

//|     import sys
//|     def readfrom_into(
//|         self, address: int, buffer: WriteableBuffer, *, start: int = 0, end: int = sys.maxsize
//|     ) -> None:
//|         """Read into ``buffer`` from the device selected by ``address``.
//|         The number of bytes read will be the length of ``buffer``.
//|         At least one byte must be read.
//|
//|         If ``start`` or ``end`` is provided, then the buffer will be sliced
//|         as if ``buffer[start:end]``. This will not cause an allocation like
//|         ``buf[start:end]`` will so it saves memory.
//|
//|         :param int address: 7-bit device address
//|         :param WriteableBuffer buffer: buffer to write into
//|         :param int start: Index to start writing at
//|         :param int end: Index to write up to but not include"""
//|         ...
// Shared arg parsing for readfrom_into and writeto_then_readfrom.
STATIC void readfrom(bitbangio_i2c_obj_t *self, mp_int_t address, mp_obj_t buffer, int32_t start, mp_int_t end) {
    mp_buffer_info_t bufinfo;
    mp_get_buffer_raise(buffer, &bufinfo, MP_BUFFER_WRITE);

    int stride_in_bytes = mp_binary_get_size('@', bufinfo.typecode, NULL);
    size_t length = bufinfo.len / stride_in_bytes;
    normalize_buffer_bounds(&start, end, &length);
    mp_arg_validate_length_min(length, 1, MP_QSTR_buffer);

    // Treat start and length in terms of bytes from now on.
    start *= stride_in_bytes;
    length *= stride_in_bytes;

    uint8_t status = shared_module_bitbangio_i2c_read(self, address, ((uint8_t *)bufinfo.buf) + start, length);
    if (status != 0) {
        mp_raise_OSError(status);
    }
}

STATIC mp_obj_t bitbangio_i2c_readfrom_into(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
    enum { ARG_address, ARG_buffer, ARG_start, ARG_end };
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_address,    MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
        { MP_QSTR_buffer,     MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
        { MP_QSTR_start,      MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
        { MP_QSTR_end,        MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = INT_MAX} },
    };
    bitbangio_i2c_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
    check_for_deinit(self);
    check_lock(self);
    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
    mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);

    readfrom(self, args[ARG_address].u_int, args[ARG_buffer].u_obj, args[ARG_start].u_int,
        args[ARG_end].u_int);
    return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_KW(bitbangio_i2c_readfrom_into_obj, 1, bitbangio_i2c_readfrom_into);

//|     import sys
//|     def writeto(
//|         self, address: int, buffer: ReadableBuffer, *, start: int = 0, end: int = sys.maxsize
//|     ) -> None:
//|         """Write the bytes from ``buffer`` to the device selected by ``address`` and then transmits a
//|         stop bit. Use `writeto_then_readfrom` when needing a write, no stop and repeated start
//|         before a read.
//|
//|         If ``start`` or ``end`` is provided, then the buffer will be sliced
//|         as if ``buffer[start:end]`` were passed, but without copying the data.
//|         The number of bytes written will be the length of ``buffer[start:end]``.
//|
//|         Writing a buffer or slice of length zero is permitted, as it can be used
//|         to poll for the existence of a device.
//|
//|         :param int address: 7-bit device address
//|         :param ReadableBuffer buffer: buffer containing the bytes to write
//|         :param int start: beginning of buffer slice
//|         :param int end: end of buffer slice; if not specified, use ``len(buffer)``
//|         """
//|         ...
// Shared arg parsing for writeto and writeto_then_readfrom.
STATIC void writeto(bitbangio_i2c_obj_t *self, mp_int_t address, mp_obj_t buffer, int32_t start, mp_int_t end, bool stop) {
    // get the buffer to write the data from
    mp_buffer_info_t bufinfo;
    mp_get_buffer_raise(buffer, &bufinfo, MP_BUFFER_READ);

    int stride_in_bytes = mp_binary_get_size('@', bufinfo.typecode, NULL);
    size_t length = bufinfo.len / stride_in_bytes;
    normalize_buffer_bounds(&start, end, &length);

    // Treat start and length in terms of bytes from now on.
    start *= stride_in_bytes;
    length *= stride_in_bytes;

    // Do the transfer
    uint8_t status = shared_module_bitbangio_i2c_write(self, address,
        ((uint8_t *)bufinfo.buf) + start, length,
        stop);
    if (status != 0) {
        mp_raise_OSError(status);
    }
}

STATIC mp_obj_t bitbangio_i2c_writeto(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
    enum { ARG_address, ARG_buffer, ARG_start, ARG_end };
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_address,    MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
        { MP_QSTR_buffer,     MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
        { MP_QSTR_start,      MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
        { MP_QSTR_end,        MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = INT_MAX} },
    };
    bitbangio_i2c_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
    check_for_deinit(self);
    check_lock(self);
    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
    mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);

    writeto(self, args[ARG_address].u_int, args[ARG_buffer].u_obj, args[ARG_start].u_int,
        args[ARG_end].u_int, true);
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_KW(bitbangio_i2c_writeto_obj, 1, bitbangio_i2c_writeto);


//|     import sys
//|     def writeto_then_readfrom(
//|         self,
//|         address: int,
//|         out_buffer: ReadableBuffer,
//|         in_buffer: ReadableBuffer,
//|         *,
//|         out_start: int = 0,
//|         out_end: int = sys.maxsize,
//|         in_start: int = 0,
//|         in_end: int = sys.maxsize
//|     ) -> None:
//|         """Write the bytes from ``out_buffer`` to the device selected by ``address``, generate no stop
//|         bit, generate a repeated start and read into ``in_buffer``. ``out_buffer`` and
//|         ``in_buffer`` can be the same buffer because they are used sequentially.
//|
//|         If ``out_start`` or ``out_end`` is provided, then the buffer will be sliced
//|         as if ``out_buffer[out_start:out_end]`` were passed, but without copying the data.
//|         The number of bytes written will be the length of ``out_buffer[start:end]``.
//|
//|         If ``in_start`` or ``in_end`` is provided, then the input buffer will be sliced
//|         as if ``in_buffer[in_start:in_end]`` were passed,
//|         The number of bytes read will be the length of ``out_buffer[in_start:in_end]``.
//|
//|         :param int address: 7-bit device address
//|         :param ~circuitpython_typing.ReadableBuffer out_buffer: buffer containing the bytes to write
//|         :param ~circuitpython_typing.WriteableBuffer in_buffer: buffer to write into
//|         :param int out_start: beginning of ``out_buffer`` slice
//|         :param int out_end: end of ``out_buffer`` slice; if not specified, use ``len(out_buffer)``
//|         :param int in_start: beginning of ``in_buffer`` slice
//|         :param int in_end: end of ``in_buffer slice``; if not specified, use ``len(in_buffer)``
//|         """
//|         ...
//|
STATIC mp_obj_t bitbangio_i2c_writeto_then_readfrom(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
    enum { ARG_address, ARG_out_buffer, ARG_in_buffer, ARG_out_start, ARG_out_end, ARG_in_start, ARG_in_end };
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_address,    MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
        { MP_QSTR_out_buffer, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
        { MP_QSTR_in_buffer,  MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
        { MP_QSTR_out_start,  MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
        { MP_QSTR_out_end,    MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = INT_MAX} },
        { MP_QSTR_in_start,   MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
        { MP_QSTR_in_end,     MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = INT_MAX} },
    };
    bitbangio_i2c_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
    check_for_deinit(self);
    check_lock(self);
    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
    mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);

    writeto(self, args[ARG_address].u_int, args[ARG_out_buffer].u_obj, args[ARG_out_start].u_int,
        args[ARG_out_end].u_int, false);
    readfrom(self, args[ARG_address].u_int, args[ARG_in_buffer].u_obj, args[ARG_in_start].u_int,
        args[ARG_in_end].u_int);

    return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_KW(bitbangio_i2c_writeto_then_readfrom_obj, 1, bitbangio_i2c_writeto_then_readfrom);

STATIC const mp_rom_map_elem_t bitbangio_i2c_locals_dict_table[] = {
    { MP_ROM_QSTR(MP_QSTR_deinit), MP_ROM_PTR(&bitbangio_i2c_deinit_obj) },
    { MP_ROM_QSTR(MP_QSTR___enter__), MP_ROM_PTR(&default___enter___obj) },
    { MP_ROM_QSTR(MP_QSTR___exit__), MP_ROM_PTR(&bitbangio_i2c_obj___exit___obj) },
    { MP_ROM_QSTR(MP_QSTR_scan), MP_ROM_PTR(&bitbangio_i2c_scan_obj) },

    { MP_ROM_QSTR(MP_QSTR_try_lock), MP_ROM_PTR(&bitbangio_i2c_try_lock_obj) },
    { MP_ROM_QSTR(MP_QSTR_unlock), MP_ROM_PTR(&bitbangio_i2c_unlock_obj) },

    { MP_ROM_QSTR(MP_QSTR_writeto), MP_ROM_PTR(&bitbangio_i2c_writeto_obj) },
    { MP_ROM_QSTR(MP_QSTR_readfrom_into), MP_ROM_PTR(&bitbangio_i2c_readfrom_into_obj) },
    { MP_ROM_QSTR(MP_QSTR_writeto_then_readfrom), MP_ROM_PTR(&bitbangio_i2c_writeto_then_readfrom_obj) },
};

STATIC MP_DEFINE_CONST_DICT(bitbangio_i2c_locals_dict, bitbangio_i2c_locals_dict_table);

MP_DEFINE_CONST_OBJ_TYPE(
    bitbangio_i2c_type,
    MP_QSTR_I2C,
    MP_TYPE_FLAG_NONE,
    make_new, bitbangio_i2c_make_new,
    locals_dict, &bitbangio_i2c_locals_dict
    );