mimxrt: Add the Timer class to the machine module.

It supports three hardware timer channels based on the PIT timers of the
MIMXRT MCU.  The timer id's are 0, 1 and 2.  On soft reboot all active
timers will be stopped via finalisers.

ports/mimxrt/Makefile

@@ -107,6 +107,7 @@ SRC_TINYUSB_IMX_C += \
 	$(MCU_DIR)/drivers/fsl_lpuart.c \
 	$(MCU_DIR)/drivers/fsl_flexram.c \
 	$(MCU_DIR)/drivers/fsl_flexspi.c \
+	$(MCU_DIR)/drivers/fsl_pit.c \
 	$(MCU_DIR)/drivers/fsl_trng.c \
 
 SRC_C = \
@@ -119,6 +120,7 @@ SRC_C = \
 	$(BOARD_DIR)/flash_config.c \
 	machine_led.c \
 	machine_pin.c \
+	machine_timer.c \
 	mimxrt_flash.c \
 	modutime.c \
 	modmachine.c \
@@ -144,6 +146,7 @@ SRC_S = lib/utils/gchelper_m3.s \
 SRC_QSTR += \
 	machine_led.c \
 	machine_pin.c \
+	machine_timer.c \
 	mimxrt_flash.c \
 	modutime.c \
 	modmachine.c \

ports/mimxrt/board_init.c

@@ -38,6 +38,7 @@
 #include "fsl_lpuart.h"
 
 #include "clock_config.h"
+#include "modmachine.h"
 
 volatile uint32_t systick_ms = 0;
 
@@ -78,6 +79,9 @@ void board_init(void) {
     // USB1
     //  CLOCK_EnableUsbhs1PhyPllClock(kCLOCK_Usbphy480M, 480000000U);
     //  CLOCK_EnableUsbhs1Clock(kCLOCK_Usb480M, 480000000U);
+
+    // PIT
+    machine_timer_init_PIT();
 }
 
 void USB_OTG1_IRQHandler(void) {

ports/mimxrt/machine_timer.c

@@ -0,0 +1,210 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020-2021 Damien P. George
+ * Copyright (c) 2021 Robert Hammelrath
+ *
+ * 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/mperrno.h"
+#include "py/mphal.h"
+#include "fsl_pit.h"
+#include "modmachine.h"
+
+#define ALARM_ID_INVALID (-1)
+#define TIMER_MODE_ONE_SHOT (0)
+#define TIMER_MODE_PERIODIC (1)
+#define TIMER_MIN_PERIOD 1
+
+#define alarm_callback PIT_IRQHandler
+#define PIT_SOURCE_CLOCK CLOCK_GetFreq(kCLOCK_OscClk)
+#define PIT_IRQ_ID PIT_IRQn
+
+typedef struct _machine_timer_obj_t {
+    mp_obj_base_t base;
+    int8_t id;
+    int8_t channel;
+    uint32_t mode;
+    uint32_t tick_hz;
+    uint32_t delta_us; // for periodic mode
+    mp_obj_t callback;
+} machine_timer_obj_t;
+
+static const int8_t channel_no[MICROPY_HW_PIT_NUM_CHANNELS] = {0, 2, 3}; // no channel 1
+static pit_config_t pit_config;
+
+// This is the interrupt handler
+// To tell which channel fired one has to poll the flags
+void alarm_callback(void) {
+    for (uint8_t index = 0; index < MICROPY_HW_PIT_NUM_CHANNELS; index++) {
+        uint32_t flag;
+        machine_timer_obj_t *self = MP_STATE_PORT(timer_table)[index];
+        if (self != NULL) {
+            flag = PIT_GetStatusFlags(PIT, self->channel);
+            if (flag & kPIT_TimerFlag) { // channel fired
+                PIT_ClearStatusFlags(PIT, self->channel, kPIT_TimerFlag);
+                __DSB();
+
+                mp_sched_schedule(self->callback, MP_OBJ_FROM_PTR(self));
+
+                if (self->mode == TIMER_MODE_ONE_SHOT) {
+                    PIT_StopTimer(PIT, self->channel);
+                }
+            }
+        }
+    }
+}
+
+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 = MP_OBJ_TO_PTR(self_in);
+    qstr mode = self->mode == TIMER_MODE_ONE_SHOT ? MP_QSTR_ONE_SHOT : MP_QSTR_PERIODIC;
+    mp_printf(print, "Timer(channel=%d, mode=%q, period=%d, tick_hz=%d)",
+        self->id, mode, self->delta_us / self->tick_hz, self->tick_hz);
+}
+
+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 = TIMER_MODE_PERIODIC} },
+        { MP_QSTR_callback,     MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_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_rom_obj = MP_ROM_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);
+
+    MP_STATE_PORT(timer_table)[self->id] = self;  // Insert into the table
+
+    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_us = (uint32_t)(MICROPY_FLOAT_CONST(1000000.0) / mp_obj_get_float(args[ARG_freq].u_obj));
+        #else
+        self->delta_us = 1000000 / mp_obj_get_int(args[ARG_freq].u_obj);
+        #endif
+    } else {
+        // Period specified
+        self->tick_hz = args[ARG_tick_hz].u_int;
+        self->delta_us = (uint64_t)args[ARG_period].u_int * 1000000 / self->tick_hz;
+    }
+    if (self->delta_us < TIMER_MIN_PERIOD) {
+        self->delta_us = TIMER_MIN_PERIOD;
+    }
+
+    self->callback = args[ARG_callback].u_obj;
+
+    // Set timer period for channel id
+    PIT_SetTimerPeriod(PIT, self->channel, USEC_TO_COUNT(self->delta_us, PIT_SOURCE_CLOCK));
+
+    // Enable timer interrupts for the channel
+    PIT_EnableInterrupts(PIT, self->channel, kPIT_TimerInterruptEnable);
+
+    // Enable at the NVIC
+    EnableIRQ(PIT_IRQ_ID);
+
+    // Start channel 0
+    PIT_StartTimer(PIT, self->channel);
+
+    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_with_finaliser(machine_timer_obj_t);
+    self->base.type = &machine_timer_type;
+    self->id = ALARM_ID_INVALID;
+
+    // Get timer id in the range of 0..2
+    mp_int_t id = 0;
+    if (n_args > 0) {
+        id = mp_obj_get_int(args[0]);
+        --n_args;
+        ++args;
+    }
+    if (id < 0 || id >= MICROPY_HW_PIT_NUM_CHANNELS) {
+        mp_raise_ValueError(MP_ERROR_TEXT("Timer does not exist"));
+    }
+
+    // Set initial values
+    self->id = id;
+    self->channel = channel_no[id];
+
+    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]);
+    PIT_StopTimer(PIT, self->channel);
+    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);
+    PIT_StopTimer(PIT, self->channel);
+    MP_STATE_PORT(timer_table)[self->id] = NULL;
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_timer_deinit_obj, machine_timer_deinit);
+
+// Initialize clock an first config
+void machine_timer_init_PIT(void) {
+    // PIT timer
+    // Enable clock gate for GPIO1
+    CLOCK_EnableClock(kCLOCK_Gpio1); // ?
+    // Set PERCLK_CLK source to OSC_CLK
+    CLOCK_SetMux(kCLOCK_PerclkMux, 1U);
+    // Set PERCLK_CLK divider to 1
+    CLOCK_SetDiv(kCLOCK_PerclkDiv, 0U);
+
+    PIT_GetDefaultConfig(&pit_config);
+    PIT_Init(PIT, &pit_config);
+}
+
+STATIC const mp_rom_map_elem_t machine_timer_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___del__), MP_ROM_PTR(&machine_timer_deinit_obj) },
+    { 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(TIMER_MODE_ONE_SHOT) },
+    { MP_ROM_QSTR(MP_QSTR_PERIODIC), MP_ROM_INT(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/mimxrt/modmachine.c

@@ -29,6 +29,7 @@
 #include "extmod/machine_mem.h"
 #include "led.h"
 #include "pin.h"
+#include "modmachine.h"
 
 #include CPU_HEADER_H
 
@@ -54,6 +55,7 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_LED),                 MP_ROM_PTR(&machine_led_type) },
     #endif
     { MP_ROM_QSTR(MP_QSTR_Pin),                 MP_ROM_PTR(&machine_pin_type) },
+    { MP_ROM_QSTR(MP_QSTR_Timer),               MP_ROM_PTR(&machine_timer_type) },
 };
 STATIC MP_DEFINE_CONST_DICT(machine_module_globals, machine_module_globals_table);
 

ports/mimxrt/modmachine.h

@@ -0,0 +1,36 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Damien P. George
+ * Copyright (c) 2021 Robert Hammelrath
+ *
+ * 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.
+ */
+#ifndef MICROPY_INCLUDED_MIMXRT_MODMACHINE_H
+#define MICROPY_INCLUDED_MIMXRT_MODMACHINE_H
+
+#include "py/obj.h"
+
+extern const mp_obj_type_t machine_timer_type;
+
+void machine_timer_init_PIT(void);
+
+#endif // MICROPY_INCLUDED_MIMXRT_MODMACHINE_H

ports/mimxrt/mpconfigport.h

@@ -53,6 +53,8 @@
 #define MICROPY_MODULE_BUILTIN_INIT         (1)
 #define MICROPY_MODULE_WEAK_LINKS           (1)
 #define MICROPY_CAN_OVERRIDE_BUILTINS       (1)
+#define MICROPY_ENABLE_SCHEDULER            (1)
+#define MICROPY_SCHEDULER_DEPTH             (8)
 #define MICROPY_VFS                         (1)
 #define MICROPY_MODULE_FROZEN_MPY           (1)
 #define MICROPY_QSTR_EXTRA_POOL             mp_qstr_frozen_const_pool
@@ -109,8 +111,11 @@ extern const struct _mp_obj_module_t mp_module_utime;
     { MP_ROM_QSTR(MP_QSTR_uos), MP_ROM_PTR(&mp_module_uos) }, \
     { MP_ROM_QSTR(MP_QSTR_utime), MP_ROM_PTR(&mp_module_utime) }, \
 
+#define MICROPY_HW_PIT_NUM_CHANNELS 3
+
 #define MICROPY_PORT_ROOT_POINTERS \
-    const char *readline_hist[8];
+    const char *readline_hist[8]; \
+    struct _machine_timer_obj_t *timer_table[MICROPY_HW_PIT_NUM_CHANNELS];
 
 #define MP_STATE_PORT MP_STATE_VM