esp32/machine_uart: Implement UART.RX_IDLE based on machine.Timer.

The UART.IRQ_IDLE callback is called about two character times after the
last byte, or 1 ms, whichever is larger.  For the irq, timer 0 is used.

machine_timer.c had to be reworked to make it's mechanisms available for
machine_uart.c.

The irq.flags() value is change only at a requested event.  Otherwise keep
the state.

Signed-off-by: robert-hh <robert@hammelrath.com>

ports/esp32/machine_timer.h

@@ -0,0 +1,66 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * Development of the code in this file was sponsored by Microbric Pty Ltd
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013-2015 Damien P. George
+ * Copyright (c) 2016 Paul Sokolovsky
+ *
+ * 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_ESP32_MACHINE_TIMER_H
+#define MICROPY_INCLUDED_ESP32_MACHINE_TIMER_H
+
+#include "hal/timer_hal.h"
+#include "hal/timer_ll.h"
+#include "soc/timer_periph.h"
+
+#define TIMER_DIVIDER  8
+
+// TIMER_BASE_CLK is normally 80MHz. TIMER_DIVIDER ought to divide this exactly
+#define TIMER_SCALE    (APB_CLK_FREQ / TIMER_DIVIDER)
+
+#define TIMER_FLAGS    0
+
+typedef struct _machine_timer_obj_t {
+    mp_obj_base_t base;
+
+    timer_hal_context_t hal_context;
+    mp_uint_t group;
+    mp_uint_t index;
+
+    mp_uint_t repeat;
+    // ESP32 timers are 64-bit
+    uint64_t period;
+
+    mp_obj_t callback;
+
+    intr_handle_t handle;
+
+    struct _machine_timer_obj_t *next;
+} machine_timer_obj_t;
+
+machine_timer_obj_t *machine_timer_create(mp_uint_t timer);
+void machine_timer_enable(machine_timer_obj_t *self, void (*timer_isr));
+void machine_timer_disable(machine_timer_obj_t *self);
+
+#endif // MICROPY_INCLUDED_ESP32_MACHINE_TIMER_H