stmhal: Add beginnings of port-specific machine.I2C implementation.

This allows one to construct an I2C object using ids that are specific
to the stmhal port, eg machine.I2C('X').  Right now the implementation
of I2C uses software I2C but the idea is to just change the C-level I2C
protocol functions to hardware implementations later on.

stmhal/Makefile

@@ -145,6 +145,7 @@ SRC_C = \
 	pybstdio.c \
 	help.c \
 	input.c \
+	machine_i2c.c \
 	modmachine.c \
 	modpyb.c \
 	modstm.c \

stmhal/machine_i2c.c

+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 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 <stdio.h>
+#include <string.h>
+
+#include "py/runtime.h"
+#include "py/mphal.h"
+#include "extmod/machine_i2c.h"
+#include "genhdr/pins.h"
+
+// for now we use the SW I2C implementation for the HW peripheral I2C blocks
+typedef mp_machine_soft_i2c_obj_t machine_hard_i2c_obj_t;
+
+STATIC const mp_obj_type_t machine_hard_i2c_type;
+
+STATIC machine_hard_i2c_obj_t machine_hard_i2c_obj[] = {
+    #if defined(MICROPY_HW_I2C1_SCL)
+    {{&machine_hard_i2c_type}, 1, 500, &MICROPY_HW_I2C1_SCL, &MICROPY_HW_I2C1_SDA},
+    #else
+    {{NULL}, 0, 0, NULL, NULL},
+    #endif
+    #if defined(MICROPY_HW_I2C2_SCL)
+    {{&machine_hard_i2c_type}, 1, 500, &MICROPY_HW_I2C2_SCL, &MICROPY_HW_I2C2_SDA},
+    #else
+    {{NULL}, 0, 0, NULL, NULL},
+    #endif
+    #if defined(MICROPY_HW_I2C3_SCL)
+    {{&machine_hard_i2c_type}, 1, 500, &MICROPY_HW_I2C3_SCL, &MICROPY_HW_I2C3_SDA},
+    #else
+    {{NULL}, 0, 0, NULL, NULL},
+    #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);
+}
+
+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) {
+    // parse args
+    enum { ARG_id, ARG_scl, ARG_sda, ARG_freq, ARG_timeout };
+    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 = -1} },
+        { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+    };
+    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);
+
+    // work out i2c bus
+    int i2c_id = 0;
+    if (MP_OBJ_IS_STR(args[ARG_id].u_obj)) {
+        const char *port = mp_obj_str_get_str(args[ARG_id].u_obj);
+        if (0) {
+        #ifdef MICROPY_HW_I2C1_NAME
+        } else if (strcmp(port, MICROPY_HW_I2C1_NAME) == 0) {
+            i2c_id = 1;
+        #endif
+        #ifdef MICROPY_HW_I2C2_NAME
+        } else if (strcmp(port, MICROPY_HW_I2C2_NAME) == 0) {
+            i2c_id = 2;
+        #endif
+        #ifdef MICROPY_HW_I2C3_NAME
+        } else if (strcmp(port, MICROPY_HW_I2C3_NAME) == 0) {
+            i2c_id = 3;
+        #endif
+        } else {
+            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
+                "I2C(%s) does not exist", port));
+        }
+    } else {
+        i2c_id = mp_obj_get_int(args[ARG_id].u_obj);
+        if (i2c_id < 1 || i2c_id > MP_ARRAY_SIZE(machine_hard_i2c_obj)
+            || machine_hard_i2c_obj[i2c_id - 1].base.type == NULL) {
+            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
+                "I2C(%d) does not exist", i2c_id));
+        }
+    }
+
+    // get static peripheral object
+    machine_hard_i2c_obj_t *self = &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("explicit choice of scl/sda is not implemented");
+    }
+
+    // set parameters
+    if (args[ARG_freq].u_int != -1) {
+        if (args[ARG_freq].u_int >= 1000000) {
+            // allow fastest possible bit-bang rate
+            self->us_delay = 0;
+        } else {
+            self->us_delay = 500000 / args[ARG_freq].u_int;
+            if (self->us_delay == 0) {
+                self->us_delay = 1;
+            }
+        }
+    }
+    if (args[ARG_timeout].u_int != -1) {
+        self->us_timeout = args[ARG_timeout].u_int;
+    }
+
+    // init pins
+    mp_hal_pin_open_drain(self->scl);
+    mp_hal_pin_open_drain(self->sda);
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+STATIC const mp_machine_i2c_p_t machine_hard_i2c_p = {
+    .readfrom = mp_machine_soft_i2c_readfrom,
+    .writeto = mp_machine_soft_i2c_writeto,
+};
+
+STATIC const mp_obj_type_t machine_hard_i2c_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_I2C,
+    .print = machine_hard_i2c_print,
+    .make_new = machine_hard_i2c_make_new,
+    .protocol = &machine_hard_i2c_p,
+    .locals_dict = (mp_obj_dict_t*)&mp_machine_soft_i2c_locals_dict,
+};

stmhal/mpconfigport.h

@@ -103,6 +103,7 @@
 #define MICROPY_PY_MACHINE          (1)
 #define MICROPY_PY_MACHINE_PULSE    (1)
 #define MICROPY_PY_MACHINE_I2C      (1)
+#define MICROPY_PY_MACHINE_I2C_MAKE_NEW machine_hard_i2c_make_new
 #define MICROPY_PY_MACHINE_SPI      (1)
 #define MICROPY_PY_MACHINE_SPI_MIN_DELAY (0)
 #define MICROPY_PY_FRAMEBUF         (1)