zephyr/machine_spi: Add support for hardware SPI.

Adds support for hardware SPI to the zephyr port.  Consistent with other
ports, such as rp2 and stm32, we only implement the SPI protocol functions
(init and transfer).  Explicit sck/mosi/miso selection is not supported
and new SPI instances are initialized with default values.

ports/zephyr/CMakeLists.txt

@@ -38,6 +38,7 @@ set(MICROPY_SOURCE_PORT
     main.c
     help.c
     machine_i2c.c
+    machine_spi.c
     machine_pin.c
     machine_uart.c
     modbluetooth_zephyr.c

ports/zephyr/README.md

@@ -15,6 +15,7 @@ Features supported at this time:
 * `utime` module for time measurements and delays.
 * `machine.Pin` class for GPIO control, with IRQ support.
 * `machine.I2C` class for I2C control.
+* `machine.SPI` class for SPI control.
 * `usocket` module for networking (IPv4/IPv6).
 * "Frozen modules" support to allow to bundle Python modules together
   with firmware. Including complete applications, including with
@@ -135,6 +136,14 @@ Example of using I2C to scan for I2C slaves:
     i2c = I2C("I2C_0")
     i2c.scan()
 
+Example of using SPI to write a buffer to the MOSI pin:
+
+    from machine import SPI
+
+    spi = SPI("SPI_0")
+    spi.init(baudrate=500000, polarity=1, phase=1, bits=8, firstbit=SPI.MSB)
+    spi.write(b'abcd')
+
 
 Minimal build
 -------------

ports/zephyr/boards/frdm_k64f.conf

@@ -3,6 +3,7 @@ CONFIG_NET_L2_ETHERNET=y
 
 # Hardware features
 CONFIG_I2C=y
+CONFIG_SPI=y
 
 # Sensor drivers
 CONFIG_FXOS8700=y

ports/zephyr/boards/mimxrt685_evk_cm33.conf

+# Hardware features
+CONFIG_SPI=y

ports/zephyr/machine_spi.c

+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright 2021 NXP
+ *
+ * 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 <stdio.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <zephyr.h>
+#include <drivers/spi.h>
+
+#include "py/runtime.h"
+#include "py/gc.h"
+#include "py/mphal.h"
+#include "py/mperrno.h"
+#include "extmod/machine_spi.h"
+#include "modmachine.h"
+
+#if MICROPY_PY_MACHINE_SPI
+
+#define DEFAULT_SPI_BAUDRATE    (50000)
+#define DEFAULT_SPI_POLARITY    (0)
+#define DEFAULT_SPI_PHASE       (0)
+#define DEFAULT_SPI_BITS        (8)
+#define DEFAULT_SPI_FIRSTBIT    (SPI_TRANSFER_MSB)
+#define SPI_LOOP                (0)    // For testing, enable loop mode by setting SPI_LOOP (1)
+
+typedef struct _machine_hard_spi_obj_t {
+    mp_obj_base_t base;
+    const struct device *dev;
+    struct spi_config config;
+} machine_hard_spi_obj_t;
+
+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 = self_in;
+    mp_printf(print, "SPI(%s, baudrate=%u, polarity=%u, phase=%u, bits=%u, firstbit=%s)",
+        self->dev->name,
+        self->config.frequency,
+        (self->config.operation & 0x2) >> 1,
+        (self->config.operation & 0x4) >> 2,
+        (self->config.operation & ~0x1F) >> 5,
+        ((self->config.operation & 0x10) >> 4) == SPI_TRANSFER_MSB ? "MSB" : "LSB");
+}
+
+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_REQUIRED | MP_ARG_OBJ },
+        { MP_QSTR_baudrate, MP_ARG_INT, {.u_int = DEFAULT_SPI_BAUDRATE} },
+        { MP_QSTR_polarity, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = DEFAULT_SPI_POLARITY} },
+        { MP_QSTR_phase, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = DEFAULT_SPI_PHASE} },
+        { MP_QSTR_bits, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = DEFAULT_SPI_BITS} },
+        { MP_QSTR_firstbit, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = DEFAULT_SPI_FIRSTBIT} },
+        { 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);
+
+    const char *dev_name = mp_obj_str_get_str(args[ARG_id].u_obj);
+    const struct device *dev = device_get_binding(dev_name);
+
+    if (dev == NULL) {
+        mp_raise_ValueError(MP_ERROR_TEXT("device not found"));
+    }
+
+    if ((args[ARG_sck].u_obj != MP_OBJ_NULL) || (args[ARG_miso].u_obj != MP_OBJ_NULL) || (args[ARG_mosi].u_obj != MP_OBJ_NULL)) {
+        mp_raise_NotImplementedError(MP_ERROR_TEXT("explicit choice of sck/miso/mosi is not implemented"));
+    }
+
+    struct spi_config cfg = {
+        .frequency = args[ARG_baudrate].u_int,
+        .operation = (SPI_OP_MODE_MASTER |
+            args[ARG_polarity].u_int << 1 |
+                args[ARG_phase].u_int << 2 |
+                SPI_LOOP << 3 |
+                args[ARG_firstbit].u_int << 4 |
+                args[ARG_bits].u_int << 5 |
+                SPI_LINES_SINGLE),
+        .slave = 0,
+        .cs = NULL
+    };
+
+    machine_hard_spi_obj_t *self = m_new_obj(machine_hard_spi_obj_t);
+
+    self->base.type = &machine_hard_spi_type;
+    self->dev = dev;
+    self->config = cfg;
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+STATIC void machine_hard_spi_init(mp_obj_base_t *obj, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    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);
+
+    machine_hard_spi_obj_t *self = (machine_hard_spi_obj_t *)obj;
+
+    uint32_t baudrate;
+    uint16_t operation = self->config.operation;
+
+    if (args[ARG_baudrate].u_int != -1) {
+        baudrate = args[ARG_baudrate].u_int;
+    } else {
+        baudrate = self->config.frequency;
+    }
+
+    if (args[ARG_polarity].u_int != -1) {
+        operation = (operation & ~0x2) | (args[ARG_polarity].u_int << 1);
+    }
+
+    if (args[ARG_phase].u_int != -1) {
+        operation = (operation & ~0x4) | (args[ARG_phase].u_int << 2);
+    }
+
+    if (args[ARG_bits].u_int != -1) {
+        operation = (operation & 0x1F) | (args[ARG_bits].u_int << 5);
+    }
+
+    if (args[ARG_firstbit].u_int != -1) {
+        operation = (operation & ~0x10) | (args[ARG_firstbit].u_int << 4);
+    }
+
+    struct spi_config cfg = {
+        .frequency = baudrate,
+        .operation = operation,
+        .slave = 0,
+        .cs = NULL
+    };
+
+    self->config = cfg;
+}
+
+STATIC void machine_hard_spi_transfer(mp_obj_base_t *obj, size_t len, const uint8_t *src, uint8_t *dest) {
+    machine_hard_spi_obj_t *self = (machine_hard_spi_obj_t *)obj;
+
+    int ret;
+
+    struct spi_buf tx_bufs[1];
+    tx_bufs[0].buf = (uint8_t *)src;
+    tx_bufs[0].len = len;
+    const struct spi_buf_set tx = {
+        .buffers = tx_bufs,
+        .count = ARRAY_SIZE(tx_bufs)
+    };
+
+    struct spi_buf rx_bufs[1];
+    rx_bufs[0].buf = dest;
+    rx_bufs[0].len = len;
+    const struct spi_buf_set rx = {
+        .buffers = rx_bufs,
+        .count = ARRAY_SIZE(rx_bufs)
+    };
+
+    ret = spi_transceive(self->dev, &self->config, &tx, &rx);
+
+    if (ret < 0) {
+        mp_raise_OSError(-ret);
+    }
+}
+
+STATIC const mp_machine_spi_p_t machine_hard_spi_p = {
+    .init = machine_hard_spi_init,
+    .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 = machine_hard_spi_make_new,
+    .protocol = &machine_hard_spi_p,
+    .locals_dict = (mp_obj_dict_t *)&mp_machine_spi_locals_dict,
+};
+
+#endif // MICROPY_PY_MACHINE_SPI

ports/zephyr/modmachine.c

@@ -36,6 +36,7 @@
 #include "extmod/machine_signal.h"
 #include "extmod/machine_pulse.h"
 #include "extmod/machine_i2c.h"
+#include "extmod/machine_spi.h"
 #include "modmachine.h"
 
 #if MICROPY_PY_MACHINE
@@ -70,6 +71,9 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     #if MICROPY_PY_MACHINE_I2C
     { MP_ROM_QSTR(MP_QSTR_I2C), MP_ROM_PTR(&machine_hard_i2c_type) },
     #endif
+    #if MICROPY_PY_MACHINE_SPI
+    { MP_ROM_QSTR(MP_QSTR_SPI), MP_ROM_PTR(&machine_hard_spi_type) },
+    #endif
     { MP_ROM_QSTR(MP_QSTR_UART), MP_ROM_PTR(&machine_uart_type) },
     { MP_ROM_QSTR(MP_QSTR_Pin), MP_ROM_PTR(&machine_pin_type) },
     { MP_ROM_QSTR(MP_QSTR_Signal), MP_ROM_PTR(&machine_signal_type) },

ports/zephyr/modmachine.h

@@ -5,6 +5,7 @@
 
 extern const mp_obj_type_t machine_pin_type;
 extern const mp_obj_type_t machine_hard_i2c_type;
+extern const mp_obj_type_t machine_hard_spi_type;
 extern const mp_obj_type_t machine_uart_type;
 
 MP_DECLARE_CONST_FUN_OBJ_0(machine_info_obj);

ports/zephyr/mpconfigport.h

@@ -29,6 +29,7 @@
 #include "autoconf.h"
 // Included here to get basic Zephyr environment (macros, etc.)
 #include <zephyr.h>
+#include <drivers/spi.h>
 
 // Usually passed from Makefile
 #ifndef MICROPY_HEAP_SIZE
@@ -62,6 +63,9 @@
 #define MICROPY_PY_MICROPYTHON_MEM_INFO (1)
 #define MICROPY_PY_MACHINE          (1)
 #define MICROPY_PY_MACHINE_I2C      (1)
+#define MICROPY_PY_MACHINE_SPI      (1)
+#define MICROPY_PY_MACHINE_SPI_MSB (SPI_TRANSFER_MSB)
+#define MICROPY_PY_MACHINE_SPI_LSB (SPI_TRANSFER_LSB)
 #define MICROPY_PY_MACHINE_PIN_MAKE_NEW mp_pin_make_new
 #define MICROPY_MODULE_WEAK_LINKS   (1)
 #define MICROPY_PY_STRUCT           (0)