rp2: Add new port to Raspberry Pi RP2 microcontroller.

This commit adds a new port "rp2" which targets the new Raspberry Pi RP2040
microcontroller.

The build system uses pure cmake (with a small Makefile wrapper for
convenience).  The USB driver is TinyUSB, and there is a machine module
with most of the standard classes implemented.  Some examples are provided
in the examples/rp2/ directory.

Work done in collaboration with Graham Sanderson.

Signed-off-by: Damien George <damien@micropython.org>

1 files changed, 161 insertions, 0 deletions

diff --git a/ports/rp2/machine_i2c.c b/ports/rp2/machine_i2c.c
new file mode 100644
index 000000000..0852cc199
--- /dev/null
+++ b/ports/rp2/machine_i2c.c
@@ -0,0 +1,161 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020-2021 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/machine_i2c.h"
+#include "modmachine.h"
+
+#include "hardware/i2c.h"
+
+#define DEFAULT_I2C_FREQ (400000)
+#define DEFAULT_I2C0_SCL (9)
+#define DEFAULT_I2C0_SDA (8)
+#define DEFAULT_I2C1_SCL (7)
+#define DEFAULT_I2C1_SDA (6)
+
+// SDA/SCL on even/odd pins, I2C0/I2C1 on even/odd pairs of pins.
+#define IS_VALID_SCL(i2c, pin) (((pin) & 1) == 1 && (((pin) & 2) >> 1) == (i2c))
+#define IS_VALID_SDA(i2c, pin) (((pin) & 1) == 0 && (((pin) & 2) >> 1) == (i2c))
+
+typedef struct _machine_i2c_obj_t {
+    mp_obj_base_t base;
+    i2c_inst_t *const i2c_inst;
+    uint8_t i2c_id;
+    uint8_t scl;
+    uint8_t sda;
+    uint32_t freq;
+} machine_i2c_obj_t;
+
+STATIC machine_i2c_obj_t machine_i2c_obj[] = {
+    {{&machine_hw_i2c_type}, i2c0, 0, DEFAULT_I2C0_SCL, DEFAULT_I2C0_SDA, 0},
+    {{&machine_hw_i2c_type}, i2c1, 1, DEFAULT_I2C1_SCL, DEFAULT_I2C1_SDA, 0},
+};
+
+STATIC void machine_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_printf(print, "I2C(%u, freq=%u, scl=%u, sda=%u)",
+        self->i2c_id, self->freq, self->scl, self->sda);
+}
+
+mp_obj_t machine_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_id, ARG_freq, ARG_scl, ARG_sda };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_id, MP_ARG_REQUIRED | MP_ARG_OBJ },
+        { MP_QSTR_freq, MP_ARG_INT, {.u_int = DEFAULT_I2C_FREQ} },
+        { MP_QSTR_scl, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+        { MP_QSTR_sda, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+    };
+
+    // Parse args.
+    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 I2C bus.
+    int i2c_id = mp_obj_get_int(args[ARG_id].u_obj);
+    if (i2c_id < 0 || i2c_id >= MP_ARRAY_SIZE(machine_i2c_obj)) {
+        mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("I2C(%d) doesn't exist"), i2c_id);
+    }
+
+    // Get static peripheral object.
+    machine_i2c_obj_t *self = (machine_i2c_obj_t *)&machine_i2c_obj[i2c_id];
+
+    // Set SCL/SDA pins if configured.
+    if (args[ARG_scl].u_obj != mp_const_none) {
+        int scl = mp_hal_get_pin_obj(args[ARG_scl].u_obj);
+        if (!IS_VALID_SCL(self->i2c_id, scl)) {
+            mp_raise_ValueError(MP_ERROR_TEXT("bad SCL pin"));
+        }
+        self->scl = scl;
+    }
+    if (args[ARG_sda].u_obj != mp_const_none) {
+        int sda = mp_hal_get_pin_obj(args[ARG_sda].u_obj);
+        if (!IS_VALID_SDA(self->i2c_id, sda)) {
+            mp_raise_ValueError(MP_ERROR_TEXT("bad SDA pin"));
+        }
+        self->sda = sda;
+    }
+
+    // Initialise the I2C peripheral if any arguments given, or it was not initialised previously.
+    if (n_args > 1 || n_kw > 0 || self->freq == 0) {
+        self->freq = args[ARG_freq].u_int;
+        i2c_init(self->i2c_inst, self->freq);
+        self->freq = i2c_set_baudrate(self->i2c_inst, self->freq);
+        gpio_set_function(self->scl, GPIO_FUNC_I2C);
+        gpio_set_function(self->sda, GPIO_FUNC_I2C);
+        gpio_set_pulls(self->scl, true, 0);
+        gpio_set_pulls(self->sda, true, 0);
+    }
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+STATIC int machine_i2c_transfer_single(mp_obj_base_t *self_in, uint16_t addr, size_t len, uint8_t *buf, unsigned int flags) {
+    machine_i2c_obj_t *self = (machine_i2c_obj_t *)self_in;
+    int ret;
+    bool nostop = !(flags & MP_MACHINE_I2C_FLAG_STOP);
+    if (flags & MP_MACHINE_I2C_FLAG_READ) {
+        ret = i2c_read_blocking(self->i2c_inst, addr, buf, len, nostop);
+    } else {
+        if (len <= 2) {
+            // Workaround issue with hardware I2C not accepting short writes.
+            mp_machine_soft_i2c_obj_t soft_i2c = {
+                .base = { &mp_machine_soft_i2c_type },
+                .us_delay = 500000 / self->freq + 1,
+                .us_timeout = 255,
+                .scl = self->scl,
+                .sda = self->sda,
+            };
+            mp_machine_i2c_buf_t bufs = {
+                .len = len,
+                .buf = buf,
+            };
+            mp_hal_pin_open_drain(self->scl);
+            mp_hal_pin_open_drain(self->sda);
+            ret = mp_machine_soft_i2c_transfer(&soft_i2c.base, addr, 1, &bufs, flags);
+            gpio_set_function(self->scl, GPIO_FUNC_I2C);
+            gpio_set_function(self->sda, GPIO_FUNC_I2C);
+        } else {
+            ret = i2c_write_blocking(self->i2c_inst, addr, buf, len, nostop);
+        }
+    }
+    return (ret < 0) ? -MP_EIO : ret;
+}
+
+STATIC const mp_machine_i2c_p_t machine_i2c_p = {
+    .transfer = mp_machine_i2c_transfer_adaptor,
+    .transfer_single = machine_i2c_transfer_single,
+};
+
+const mp_obj_type_t machine_hw_i2c_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_I2C,
+    .print = machine_i2c_print,
+    .make_new = machine_i2c_make_new,
+    .protocol = &machine_i2c_p,
+    .locals_dict = (mp_obj_dict_t *)&mp_machine_i2c_locals_dict,
+};