stm32: Add machine.Timer with soft timer implementation.

This commit adds an implementation of machine.Timer backed by the soft
timer mechanism.  It allows an arbitrary number of timers with 1ms
resolution, with an associated Python callback.  The Python-level API
matches existing ports that have a soft timer, and is used as:

    from machine import Timer
    t = Timer(freq=10, callback=lambda t:print(t))
    ...
    t = Timer(mode=Timer.ONE_SHOT, period=2000, callback=lambda t:print(t))
    ...
    t.deinit()

ports/stm32/Makefile

@@ -278,6 +278,7 @@ SRC_C = \
 	machine_adc.c \
 	machine_i2c.c \
 	machine_spi.c \
+	machine_timer.c \
 	machine_uart.c \
 	modmachine.c \
 	modpyb.c \

ports/stm32/machine_timer.c

@@ -0,0 +1,132 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 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 "softtimer.h"
+
+typedef soft_timer_entry_t machine_timer_obj_t;
+
+const mp_obj_type_t machine_timer_type;
+
+STATIC void machine_timer_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    machine_timer_obj_t *self = self_in;
+    qstr mode = self->mode == SOFT_TIMER_MODE_ONE_SHOT ? MP_QSTR_ONE_SHOT : MP_QSTR_PERIODIC;
+    mp_printf(print, "Timer(mode=%q, period=%u)", mode, self->delta_ms);
+}
+
+STATIC mp_obj_t machine_timer_init_helper(machine_timer_obj_t *self, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    enum { ARG_mode, ARG_callback, ARG_period, ARG_tick_hz, ARG_freq, };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_mode,         MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = SOFT_TIMER_MODE_PERIODIC} },
+        { MP_QSTR_callback,     MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} },
+        { MP_QSTR_period,       MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0xffffffff} },
+        { MP_QSTR_tick_hz,      MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 1000} },
+        { MP_QSTR_freq,         MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} },
+    };
+
+    // 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);
+
+    self->mode = args[ARG_mode].u_int;
+    if (args[ARG_freq].u_obj != mp_const_none) {
+        // Frequency specified in Hz
+        #if MICROPY_PY_BUILTINS_FLOAT
+        self->delta_ms = 1000 / mp_obj_get_float(args[ARG_freq].u_obj);
+        #else
+        self->delta_ms = 1000 / mp_obj_get_int(args[ARG_freq].u_obj);
+        #endif
+    } else {
+        // Period specified
+        self->delta_ms = args[ARG_period].u_int * 1000 / args[ARG_tick_hz].u_int;
+    }
+    if (self->delta_ms < 1) {
+        self->delta_ms = 1;
+    }
+    self->expiry_ms = mp_hal_ticks_ms() + self->delta_ms;
+
+    self->callback = args[ARG_callback].u_obj;
+    soft_timer_insert(self);
+
+    return mp_const_none;
+}
+
+STATIC mp_obj_t machine_timer_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    machine_timer_obj_t *self = m_new_obj(machine_timer_obj_t);
+    self->base.type = &machine_timer_type;
+
+    // Get timer id (only soft timer (-1) supported at the moment)
+    mp_int_t id = -1;
+    if (n_args > 0) {
+        id = mp_obj_get_int(args[0]);
+        --n_args;
+        ++args;
+    }
+    if (id != -1) {
+        mp_raise_ValueError("Timer doesn't exist");
+    }
+
+    if (n_args > 0 || n_kw > 0) {
+        // Start the timer
+        mp_map_t kw_args;
+        mp_map_init_fixed_table(&kw_args, n_kw, args + n_args);
+        machine_timer_init_helper(self, n_args, args, &kw_args);
+    }
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+STATIC mp_obj_t machine_timer_init(size_t n_args, const mp_obj_t *args, mp_map_t *kw_args) {
+    machine_timer_obj_t *self = MP_OBJ_TO_PTR(args[0]);
+    soft_timer_remove(self);
+    return machine_timer_init_helper(self, n_args - 1, args + 1, kw_args);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(machine_timer_init_obj, 1, machine_timer_init);
+
+STATIC mp_obj_t machine_timer_deinit(mp_obj_t self_in) {
+    machine_timer_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    soft_timer_remove(self);
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_timer_deinit_obj, machine_timer_deinit);
+
+STATIC const mp_rom_map_elem_t machine_timer_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_init), MP_ROM_PTR(&machine_timer_init_obj) },
+    { MP_ROM_QSTR(MP_QSTR_deinit), MP_ROM_PTR(&machine_timer_deinit_obj) },
+
+    { MP_ROM_QSTR(MP_QSTR_ONE_SHOT), MP_ROM_INT(SOFT_TIMER_MODE_ONE_SHOT) },
+    { MP_ROM_QSTR(MP_QSTR_PERIODIC), MP_ROM_INT(SOFT_TIMER_MODE_PERIODIC) },
+};
+STATIC MP_DEFINE_CONST_DICT(machine_timer_locals_dict, machine_timer_locals_dict_table);
+
+const mp_obj_type_t machine_timer_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_Timer,
+    .print = machine_timer_print,
+    .make_new = machine_timer_make_new,
+    .locals_dict = (mp_obj_dict_t*)&machine_timer_locals_dict,
+};

ports/stm32/modmachine.c

@@ -399,8 +399,8 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_SPI),                 MP_ROM_PTR(&machine_hard_spi_type) },
     { MP_ROM_QSTR(MP_QSTR_UART),                MP_ROM_PTR(&pyb_uart_type) },
     { MP_ROM_QSTR(MP_QSTR_WDT),                 MP_ROM_PTR(&pyb_wdt_type) },
+    { MP_ROM_QSTR(MP_QSTR_Timer),               MP_ROM_PTR(&machine_timer_type) },
 #if 0
-    { MP_ROM_QSTR(MP_QSTR_Timer),               MP_ROM_PTR(&pyb_timer_type) },
     { MP_ROM_QSTR(MP_QSTR_HeartBeat),           MP_ROM_PTR(&pyb_heartbeat_type) },
     { MP_ROM_QSTR(MP_QSTR_SD),                  MP_ROM_PTR(&pyb_sd_type) },
 

ports/stm32/modmachine.h

@@ -29,6 +29,7 @@
 #include "py/obj.h"
 
 extern const mp_obj_type_t machine_adc_type;
+extern const mp_obj_type_t machine_timer_type;
 
 void machine_init(void);
 void machine_deinit(void);