stm32/spi: Split out pyb.SPI and machine.SPI bindings to their own files

The aim here is to have spi.c contain the low-level SPI driver which is
independent (not fully but close) of MicroPython objects and methods, and
the higher-level bindings are separated out to pyb_spi.c and machine_spi.c.

ports/stm32/Makefile

@@ -229,6 +229,7 @@ SRC_C = \
 	i2c.c \
 	pyb_i2c.c \
 	spi.c \
+	pyb_spi.c \
 	qspi.c \
 	uart.c \
 	can.c \
@@ -237,6 +238,7 @@ SRC_C = \
 	gccollect.c \
 	help.c \
 	machine_i2c.c \
+	machine_spi.c \
 	modmachine.c \
 	modpyb.c \
 	modstm.c \

ports/stm32/machine_spi.c

+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013-2018 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 "extmod/machine_spi.h"
+#include "spi.h"
+
+/******************************************************************************/
+// Implementation of hard SPI for machine module
+
+STATIC const machine_hard_spi_obj_t machine_hard_spi_obj[] = {
+    {{&machine_hard_spi_type}, &spi_obj[0]},
+    {{&machine_hard_spi_type}, &spi_obj[1]},
+    {{&machine_hard_spi_type}, &spi_obj[2]},
+    {{&machine_hard_spi_type}, &spi_obj[3]},
+    {{&machine_hard_spi_type}, &spi_obj[4]},
+    {{&machine_hard_spi_type}, &spi_obj[5]},
+};
+
+STATIC void machine_hard_spi_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    machine_hard_spi_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    spi_print(print, self->spi, false);
+}
+
+mp_obj_t machine_hard_spi_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
+    enum { ARG_id, ARG_baudrate, ARG_polarity, ARG_phase, ARG_bits, ARG_firstbit, ARG_sck, ARG_mosi, ARG_miso };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_id,       MP_ARG_OBJ, {.u_obj = MP_OBJ_NEW_SMALL_INT(-1)} },
+        { MP_QSTR_baudrate, MP_ARG_INT, {.u_int = 500000} },
+        { MP_QSTR_polarity, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
+        { MP_QSTR_phase,    MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
+        { MP_QSTR_bits,     MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 8} },
+        { MP_QSTR_firstbit, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = SPI_FIRSTBIT_MSB} },
+        { MP_QSTR_sck,      MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_mosi,     MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_miso,     MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    };
+    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 spi_id = spi_find_index(args[ARG_id].u_obj);
+    const machine_hard_spi_obj_t *self = &machine_hard_spi_obj[spi_id - 1];
+
+    // here we would check the sck/mosi/miso pins and configure them, but it's not implemented
+    if (args[ARG_sck].u_obj != MP_OBJ_NULL
+        || args[ARG_mosi].u_obj != MP_OBJ_NULL
+        || args[ARG_miso].u_obj != MP_OBJ_NULL) {
+        mp_raise_ValueError("explicit choice of sck/mosi/miso is not implemented");
+    }
+
+    // set the SPI configuration values
+    SPI_InitTypeDef *init = &self->spi->spi->Init;
+    init->Mode = SPI_MODE_MASTER;
+
+    // these parameters are not currently configurable
+    init->Direction = SPI_DIRECTION_2LINES;
+    init->NSS = SPI_NSS_SOFT;
+    init->TIMode = SPI_TIMODE_DISABLE;
+    init->CRCCalculation = SPI_CRCCALCULATION_DISABLE;
+    init->CRCPolynomial = 0;
+
+    // set configurable paramaters
+    spi_set_params(self->spi, 0xffffffff, args[ARG_baudrate].u_int,
+        args[ARG_polarity].u_int, args[ARG_phase].u_int, args[ARG_bits].u_int,
+        args[ARG_firstbit].u_int);
+
+    // init the SPI bus
+    spi_init(self->spi, false);
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+STATIC void machine_hard_spi_init(mp_obj_base_t *self_in, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    machine_hard_spi_obj_t *self = (machine_hard_spi_obj_t*)self_in;
+
+    enum { ARG_baudrate, ARG_polarity, ARG_phase, ARG_bits, ARG_firstbit };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_baudrate, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_polarity, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_phase,    MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_bits,     MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_firstbit, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+    };
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    // set the SPI configuration values
+    spi_set_params(self->spi, 0xffffffff, args[ARG_baudrate].u_int,
+        args[ARG_polarity].u_int, args[ARG_phase].u_int, args[ARG_bits].u_int,
+        args[ARG_firstbit].u_int);
+
+    // re-init the SPI bus
+    spi_init(self->spi, false);
+}
+
+STATIC void machine_hard_spi_deinit(mp_obj_base_t *self_in) {
+    machine_hard_spi_obj_t *self = (machine_hard_spi_obj_t*)self_in;
+    spi_deinit(self->spi);
+}
+
+STATIC void machine_hard_spi_transfer(mp_obj_base_t *self_in, size_t len, const uint8_t *src, uint8_t *dest) {
+    machine_hard_spi_obj_t *self = (machine_hard_spi_obj_t*)self_in;
+    spi_transfer(self->spi, len, src, dest, SPI_TRANSFER_TIMEOUT(len));
+}
+
+STATIC const mp_machine_spi_p_t machine_hard_spi_p = {
+    .init = machine_hard_spi_init,
+    .deinit = machine_hard_spi_deinit,
+    .transfer = machine_hard_spi_transfer,
+};
+
+const mp_obj_type_t machine_hard_spi_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_SPI,
+    .print = machine_hard_spi_print,
+    .make_new = mp_machine_spi_make_new, // delegate to master constructor
+    .protocol = &machine_hard_spi_p,
+    .locals_dict = (mp_obj_dict_t*)&mp_machine_spi_locals_dict,
+};

ports/stm32/pyb_spi.c

+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013-2018 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 "extmod/machine_spi.h"
+#include "bufhelper.h"
+#include "spi.h"
+
+/******************************************************************************/
+// MicroPython bindings for legacy pyb API
+
+// class pyb.SPI - a master-driven serial protocol
+//
+// SPI is a serial protocol that is driven by a master.  At the physical level
+// there are 3 lines: SCK, MOSI, MISO.
+//
+// See usage model of I2C; SPI is very similar.  Main difference is
+// parameters to init the SPI bus:
+//
+//     from pyb import SPI
+//     spi = SPI(1, SPI.MASTER, baudrate=600000, polarity=1, phase=0, crc=0x7)
+//
+// Only required parameter is mode, SPI.MASTER or SPI.SLAVE.  Polarity can be
+// 0 or 1, and is the level the idle clock line sits at.  Phase can be 0 or 1
+// to sample data on the first or second clock edge respectively.  Crc can be
+// None for no CRC, or a polynomial specifier.
+//
+// Additional method for SPI:
+//
+//     data = spi.send_recv(b'1234')        # send 4 bytes and receive 4 bytes
+//     buf = bytearray(4)
+//     spi.send_recv(b'1234', buf)          # send 4 bytes and receive 4 into buf
+//     spi.send_recv(buf, buf)              # send/recv 4 bytes from/to buf
+
+STATIC const pyb_spi_obj_t pyb_spi_obj[] = {
+    {{&pyb_spi_type}, &spi_obj[0]},
+    {{&pyb_spi_type}, &spi_obj[1]},
+    {{&pyb_spi_type}, &spi_obj[2]},
+    {{&pyb_spi_type}, &spi_obj[3]},
+    {{&pyb_spi_type}, &spi_obj[4]},
+    {{&pyb_spi_type}, &spi_obj[5]},
+};
+
+STATIC void pyb_spi_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    pyb_spi_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    spi_print(print, self->spi, true);
+}
+
+// init(mode, baudrate=328125, *, polarity=1, phase=0, bits=8, firstbit=SPI.MSB, ti=False, crc=None)
+//
+// Initialise the SPI bus with the given parameters:
+//   - `mode` must be either `SPI.MASTER` or `SPI.SLAVE`.
+//   - `baudrate` is the SCK clock rate (only sensible for a master).
+STATIC mp_obj_t pyb_spi_init_helper(const pyb_spi_obj_t *self, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_mode,     MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
+        { MP_QSTR_baudrate, MP_ARG_INT, {.u_int = 328125} },
+        { MP_QSTR_prescaler, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0xffffffff} },
+        { MP_QSTR_polarity, MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = 1} },
+        { MP_QSTR_phase,    MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = 0} },
+        { MP_QSTR_dir,      MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = SPI_DIRECTION_2LINES} },
+        { MP_QSTR_bits,     MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = 8} },
+        { MP_QSTR_nss,      MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = SPI_NSS_SOFT} },
+        { MP_QSTR_firstbit, MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = SPI_FIRSTBIT_MSB} },
+        { MP_QSTR_ti,       MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
+        { MP_QSTR_crc,      MP_ARG_KW_ONLY | MP_ARG_OBJ,  {.u_rom_obj = MP_ROM_PTR(&mp_const_none_obj)} },
+    };
+
+    // parse args
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    // set the SPI configuration values
+    SPI_InitTypeDef *init = &self->spi->spi->Init;
+    init->Mode = args[0].u_int;
+
+    spi_set_params(self->spi, args[2].u_int, args[1].u_int, args[3].u_int, args[4].u_int,
+        args[6].u_int, args[8].u_int);
+
+    init->Direction = args[5].u_int;
+    init->NSS = args[7].u_int;
+    init->TIMode = args[9].u_bool ? SPI_TIMODE_ENABLE : SPI_TIMODE_DISABLE;
+    if (args[10].u_obj == mp_const_none) {
+        init->CRCCalculation = SPI_CRCCALCULATION_DISABLE;
+        init->CRCPolynomial = 0;
+    } else {
+        init->CRCCalculation = SPI_CRCCALCULATION_ENABLE;
+        init->CRCPolynomial = mp_obj_get_int(args[10].u_obj);
+    }
+
+    // init the SPI bus
+    spi_init(self->spi, init->NSS != SPI_NSS_SOFT);
+
+    return mp_const_none;
+}
+
+// constructor(bus, ...)
+//
+// Construct an SPI object on the given bus.  `bus` can be 1 or 2.
+// With no additional parameters, the SPI object is created but not
+// initialised (it has the settings from the last initialisation of
+// the bus, if any).  If extra arguments are given, the bus is initialised.
+// See `init` for parameters of initialisation.
+//
+// The physical pins of the SPI busses are:
+//   - `SPI(1)` is on the X position: `(NSS, SCK, MISO, MOSI) = (X5, X6, X7, X8) = (PA4, PA5, PA6, PA7)`
+//   - `SPI(2)` is on the Y position: `(NSS, SCK, MISO, MOSI) = (Y5, Y6, Y7, Y8) = (PB12, PB13, PB14, PB15)`
+//
+// At the moment, the NSS pin is not used by the SPI driver and is free
+// for other use.
+STATIC mp_obj_t pyb_spi_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    // check arguments
+    mp_arg_check_num(n_args, n_kw, 1, MP_OBJ_FUN_ARGS_MAX, true);
+
+    // work out SPI bus
+    int spi_id = spi_find_index(args[0]);
+
+    // get SPI object
+    const pyb_spi_obj_t *spi_obj = &pyb_spi_obj[spi_id - 1];
+
+    if (n_args > 1 || n_kw > 0) {
+        // start the peripheral
+        mp_map_t kw_args;
+        mp_map_init_fixed_table(&kw_args, n_kw, args + n_args);
+        pyb_spi_init_helper(spi_obj, n_args - 1, args + 1, &kw_args);
+    }
+
+    return MP_OBJ_FROM_PTR(spi_obj);
+}
+
+STATIC mp_obj_t pyb_spi_init(size_t n_args, const mp_obj_t *args, mp_map_t *kw_args) {
+    return pyb_spi_init_helper(MP_OBJ_TO_PTR(args[0]), n_args - 1, args + 1, kw_args);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_spi_init_obj, 1, pyb_spi_init);
+
+// deinit()
+// Turn off the SPI bus.
+STATIC mp_obj_t pyb_spi_deinit(mp_obj_t self_in) {
+    pyb_spi_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    spi_deinit(self->spi);
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_spi_deinit_obj, pyb_spi_deinit);
+
+// send(send, *, timeout=5000)
+// Send data on the bus:
+//   - `send` is the data to send (an integer to send, or a buffer object).
+//   - `timeout` is the timeout in milliseconds to wait for the send.
+//
+// Return value: `None`.
+STATIC mp_obj_t pyb_spi_send(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    // TODO assumes transmission size is 8-bits wide
+
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_send,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
+    };
+
+    // parse args
+    pyb_spi_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
+    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);
+
+    // get the buffer to send from
+    mp_buffer_info_t bufinfo;
+    uint8_t data[1];
+    pyb_buf_get_for_send(args[0].u_obj, &bufinfo, data);
+
+    // send the data
+    spi_transfer(self->spi, bufinfo.len, bufinfo.buf, NULL, args[1].u_int);
+
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_spi_send_obj, 1, pyb_spi_send);
+
+// recv(recv, *, timeout=5000)
+//
+// Receive data on the bus:
+//   - `recv` can be an integer, which is the number of bytes to receive,
+//     or a mutable buffer, which will be filled with received bytes.
+//   - `timeout` is the timeout in milliseconds to wait for the receive.
+//
+// Return value: if `recv` is an integer then a new buffer of the bytes received,
+// otherwise the same buffer that was passed in to `recv`.
+STATIC mp_obj_t pyb_spi_recv(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    // TODO assumes transmission size is 8-bits wide
+
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_recv,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
+    };
+
+    // parse args
+    pyb_spi_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
+    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);
+
+    // get the buffer to receive into
+    vstr_t vstr;
+    mp_obj_t o_ret = pyb_buf_get_for_recv(args[0].u_obj, &vstr);
+
+    // receive the data
+    spi_transfer(self->spi, vstr.len, NULL, (uint8_t*)vstr.buf, args[1].u_int);
+
+    // return the received data
+    if (o_ret != MP_OBJ_NULL) {
+        return o_ret;
+    } else {
+        return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
+    }
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_spi_recv_obj, 1, pyb_spi_recv);
+
+// send_recv(send, recv=None, *, timeout=5000)
+//
+// Send and receive data on the bus at the same time:
+//   - `send` is the data to send (an integer to send, or a buffer object).
+//   - `recv` is a mutable buffer which will be filled with received bytes.
+//   It can be the same as `send`, or omitted.  If omitted, a new buffer will
+//   be created.
+//   - `timeout` is the timeout in milliseconds to wait for the receive.
+//
+// Return value: the buffer with the received bytes.
+STATIC mp_obj_t pyb_spi_send_recv(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    // TODO assumes transmission size is 8-bits wide
+
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_send,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_recv,    MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
+    };
+
+    // parse args
+    pyb_spi_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
+    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);
+
+    // get buffers to send from/receive to
+    mp_buffer_info_t bufinfo_send;
+    uint8_t data_send[1];
+    mp_buffer_info_t bufinfo_recv;
+    vstr_t vstr_recv;
+    mp_obj_t o_ret;
+
+    if (args[0].u_obj == args[1].u_obj) {
+        // same object for send and receive, it must be a r/w buffer
+        mp_get_buffer_raise(args[0].u_obj, &bufinfo_send, MP_BUFFER_RW);
+        bufinfo_recv = bufinfo_send;
+        o_ret = args[0].u_obj;
+    } else {
+        // get the buffer to send from
+        pyb_buf_get_for_send(args[0].u_obj, &bufinfo_send, data_send);
+
+        // get the buffer to receive into
+        if (args[1].u_obj == MP_OBJ_NULL) {
+            // only send argument given, so create a fresh buffer of the send length
+            vstr_init_len(&vstr_recv, bufinfo_send.len);
+            bufinfo_recv.len = vstr_recv.len;
+            bufinfo_recv.buf = vstr_recv.buf;
+            o_ret = MP_OBJ_NULL;
+        } else {
+            // recv argument given
+            mp_get_buffer_raise(args[1].u_obj, &bufinfo_recv, MP_BUFFER_WRITE);
+            if (bufinfo_recv.len != bufinfo_send.len) {
+                mp_raise_ValueError("recv must be same length as send");
+            }
+            o_ret = args[1].u_obj;
+        }
+    }
+
+    // do the transfer
+    spi_transfer(self->spi, bufinfo_send.len, bufinfo_send.buf, bufinfo_recv.buf, args[2].u_int);
+
+    // return the received data
+    if (o_ret != MP_OBJ_NULL) {
+        return o_ret;
+    } else {
+        return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr_recv);
+    }
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_spi_send_recv_obj, 1, pyb_spi_send_recv);
+
+STATIC const mp_rom_map_elem_t pyb_spi_locals_dict_table[] = {
+    // instance methods
+    { MP_ROM_QSTR(MP_QSTR_init), MP_ROM_PTR(&pyb_spi_init_obj) },
+    { MP_ROM_QSTR(MP_QSTR_deinit), MP_ROM_PTR(&pyb_spi_deinit_obj) },
+
+    { MP_ROM_QSTR(MP_QSTR_read), MP_ROM_PTR(&mp_machine_spi_read_obj) },
+    { MP_ROM_QSTR(MP_QSTR_readinto), MP_ROM_PTR(&mp_machine_spi_readinto_obj) },
+    { MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&mp_machine_spi_write_obj) },
+    { MP_ROM_QSTR(MP_QSTR_write_readinto), MP_ROM_PTR(&mp_machine_spi_write_readinto_obj) },
+
+    // legacy methods
+    { MP_ROM_QSTR(MP_QSTR_send), MP_ROM_PTR(&pyb_spi_send_obj) },
+    { MP_ROM_QSTR(MP_QSTR_recv), MP_ROM_PTR(&pyb_spi_recv_obj) },
+    { MP_ROM_QSTR(MP_QSTR_send_recv), MP_ROM_PTR(&pyb_spi_send_recv_obj) },
+
+    // class constants
+    /// \constant MASTER - for initialising the bus to master mode
+    /// \constant SLAVE - for initialising the bus to slave mode
+    /// \constant MSB - set the first bit to MSB
+    /// \constant LSB - set the first bit to LSB
+    { MP_ROM_QSTR(MP_QSTR_MASTER), MP_ROM_INT(SPI_MODE_MASTER) },
+    { MP_ROM_QSTR(MP_QSTR_SLAVE),  MP_ROM_INT(SPI_MODE_SLAVE) },
+    { MP_ROM_QSTR(MP_QSTR_MSB),    MP_ROM_INT(SPI_FIRSTBIT_MSB) },
+    { MP_ROM_QSTR(MP_QSTR_LSB),    MP_ROM_INT(SPI_FIRSTBIT_LSB) },
+    /* TODO
+    { MP_ROM_QSTR(MP_QSTR_DIRECTION_2LINES             ((uint32_t)0x00000000)
+    { MP_ROM_QSTR(MP_QSTR_DIRECTION_2LINES_RXONLY      SPI_CR1_RXONLY
+    { MP_ROM_QSTR(MP_QSTR_DIRECTION_1LINE              SPI_CR1_BIDIMODE
+    { MP_ROM_QSTR(MP_QSTR_NSS_SOFT                    SPI_CR1_SSM
+    { MP_ROM_QSTR(MP_QSTR_NSS_HARD_INPUT              ((uint32_t)0x00000000)
+    { MP_ROM_QSTR(MP_QSTR_NSS_HARD_OUTPUT             ((uint32_t)0x00040000)
+    */
+};
+STATIC MP_DEFINE_CONST_DICT(pyb_spi_locals_dict, pyb_spi_locals_dict_table);
+
+STATIC void spi_transfer_machine(mp_obj_base_t *self_in, size_t len, const uint8_t *src, uint8_t *dest) {
+    pyb_spi_obj_t *self = (pyb_spi_obj_t*)self_in;
+    spi_transfer(self->spi, len, src, dest, SPI_TRANSFER_TIMEOUT(len));
+}
+
+STATIC const mp_machine_spi_p_t pyb_spi_p = {
+    .transfer = spi_transfer_machine,
+};
+
+const mp_obj_type_t pyb_spi_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_SPI,
+    .print = pyb_spi_print,
+    .make_new = pyb_spi_make_new,
+    .protocol = &pyb_spi_p,
+    .locals_dict = (mp_obj_dict_t*)&pyb_spi_locals_dict,
+};

ports/stm32/spi.h

@@ -34,6 +34,16 @@ typedef struct _spi_t {
     const dma_descr_t *rx_dma_descr;
 } spi_t;
 
+typedef struct _pyb_spi_obj_t {
+    mp_obj_base_t base;
+    const spi_t *spi;
+} pyb_spi_obj_t;
+
+typedef struct _machine_hard_spi_obj_t {
+    mp_obj_base_t base;
+    const spi_t *spi;
+} machine_hard_spi_obj_t;
+
 extern SPI_HandleTypeDef SPIHandle1;
 extern SPI_HandleTypeDef SPIHandle2;
 extern SPI_HandleTypeDef SPIHandle3;
@@ -47,8 +57,19 @@ extern const mp_obj_type_t pyb_spi_type;
 extern const mp_obj_type_t machine_soft_spi_type;
 extern const mp_obj_type_t machine_hard_spi_type;
 
+// A transfer of "len" bytes should take len*8*1000/baudrate milliseconds.
+// To simplify the calculation we assume the baudrate is never less than 8kHz
+// and use that value for the baudrate in the formula, plus a small constant.
+#define SPI_TRANSFER_TIMEOUT(len) ((len) + 100)
+
 void spi_init0(void);
 void spi_init(const spi_t *spi, bool enable_nss_pin);
+void spi_deinit(const spi_t *spi_obj);
+int spi_find_index(mp_obj_t id);
+void spi_set_params(const spi_t *spi_obj, uint32_t prescale, int32_t baudrate,
+    int32_t polarity, int32_t phase, int32_t bits, int32_t firstbit);
+void spi_transfer(const spi_t *self, size_t len, const uint8_t *src, uint8_t *dest, uint32_t timeout);
+void spi_print(const mp_print_t *print, const spi_t *spi_obj, bool legacy);
 const spi_t *spi_from_mp_obj(mp_obj_t o);
 
 #endif // MICROPY_INCLUDED_STM32_SPI_H