Update `time` to use SysTick (#274)

* atmel-samd: Add time back using the SysTick counter in the core. Fixes #261

* Switch to SysTick_Config

8 files changed, 58 insertions, 38 deletions

diff --git a/atmel-samd/Makefile b/atmel-samd/Makefile
index 7792b3bdc..49bd08722 100644
--- a/atmel-samd/Makefile
+++ b/atmel-samd/Makefile
@@ -213,11 +213,12 @@ SRC_C = \
 
 SRC_COMMON_HAL = \
 	board/__init__.c \
+	digitalio/__init__.c \
+	digitalio/DigitalInOut.c \
 	microcontroller/__init__.c \
 	microcontroller/Pin.c \
 	microcontroller/Processor.c \
-	digitalio/__init__.c \
-	digitalio/DigitalInOut.c
+	time/__init__.c
 #	analogio/__init__.c \
 	analogio/AnalogIn.c \
 	analogio/AnalogOut.c \
@@ -238,7 +239,6 @@ SRC_COMMON_HAL = \
 	pulseio/PulseOut.c \
 	pulseio/PWMOut.c \
 	storage/__init__.c \
-	time/__init__.c \
 	touchio/__init__.c \
 	touchio/TouchIn.c \
 	usb_hid/__init__.c \
diff --git a/atmel-samd/asf4_conf/samd21/peripheral_clk_config.h b/atmel-samd/asf4_conf/samd21/peripheral_clk_config.h
index c0831aae9..b38052a1b 100644
--- a/atmel-samd/asf4_conf/samd21/peripheral_clk_config.h
+++ b/atmel-samd/asf4_conf/samd21/peripheral_clk_config.h
@@ -41,7 +41,7 @@
  * \brief CPU's Clock frequency
  */
 #ifndef CONF_CPU_FREQUENCY
-#define CONF_CPU_FREQUENCY 1000000
+#define CONF_CPU_FREQUENCY 48000000
 #endif
 
 // <y> Core Clock Source
diff --git a/atmel-samd/common-hal/microcontroller/Processor.c b/atmel-samd/common-hal/microcontroller/Processor.c
index a037c42db..21bc9aed0 100644
--- a/atmel-samd/common-hal/microcontroller/Processor.c
+++ b/atmel-samd/common-hal/microcontroller/Processor.c
@@ -63,6 +63,7 @@
 
 #include "common-hal/microcontroller/Processor.h"
 
+#include "peripheral_clk_config.h"
 
 // #define ADC_TEMP_SAMPLE_LENGTH    4
 // #define INT1V_VALUE_FLOAT         1.0
@@ -226,6 +227,6 @@ float common_hal_mcu_processor_get_temperature(void) {
 
 
 uint32_t common_hal_mcu_processor_get_frequency(void) {
-    return 0;
-    //return system_cpu_clock_get_hz();
+    // TODO(tannewt): Determine this dynamically.
+    return CONF_CPU_FREQUENCY;
 }
diff --git a/atmel-samd/mpconfigport.h b/atmel-samd/mpconfigport.h
index 96c0acd00..8881803e4 100644
--- a/atmel-samd/mpconfigport.h
+++ b/atmel-samd/mpconfigport.h
@@ -203,7 +203,6 @@ extern const struct _mp_obj_module_t usb_hid_module;
 // { MP_OBJ_NEW_QSTR(MP_QSTR_touchio), (mp_obj_t)&touchio_module },
 //    { MP_OBJ_NEW_QSTR(MP_QSTR_analogio), (mp_obj_t)&analogio_module },
 //    { MP_OBJ_NEW_QSTR(MP_QSTR_busio), (mp_obj_t)&busio_module },
-//    { MP_OBJ_NEW_QSTR(MP_QSTR_time), (mp_obj_t)&time_module },
 //    { MP_OBJ_NEW_QSTR(MP_QSTR_neopixel_write),(mp_obj_t)&neopixel_write_module },
 //    { MP_OBJ_NEW_QSTR(MP_QSTR_usb_hid),(mp_obj_t)&usb_hid_module },
 //    { MP_OBJ_NEW_QSTR(MP_QSTR_os), (mp_obj_t)&os_module },
@@ -213,9 +212,10 @@ extern const struct _mp_obj_module_t usb_hid_module;
 
 
 #define MICROPY_PORT_BUILTIN_MODULES \
-    { MP_OBJ_NEW_QSTR(MP_QSTR_microcontroller), (mp_obj_t)&microcontroller_module }, \
-    { MP_OBJ_NEW_QSTR(MP_QSTR_digitalio), (mp_obj_t)&digitalio_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_board), (mp_obj_t)&board_module }, \
+    { MP_OBJ_NEW_QSTR(MP_QSTR_digitalio), (mp_obj_t)&digitalio_module }, \
+    { MP_OBJ_NEW_QSTR(MP_QSTR_microcontroller), (mp_obj_t)&microcontroller_module }, \
+    { MP_OBJ_NEW_QSTR(MP_QSTR_time), (mp_obj_t)&time_module },
     EXTRA_BUILTIN_MODULES
 
 #define MICROPY_PORT_BUILTIN_DEBUG_MODULES \
diff --git a/atmel-samd/mphalport.c b/atmel-samd/mphalport.c
index 201063929..6ac66c9d1 100644
--- a/atmel-samd/mphalport.c
+++ b/atmel-samd/mphalport.c
@@ -18,6 +18,7 @@
 #include "mpconfigboard.h"
 #include "mphalport.h"
 #include "reset.h"
+#include "tick.h"
 #include "usb.h"
 
 extern struct usart_module usart_instance;
@@ -64,7 +65,7 @@ void mp_hal_delay_ms(mp_uint_t delay) {
 }
 
 void mp_hal_delay_us(mp_uint_t delay) {
-    delay_us(delay);
+    tick_delay(delay);
 }
 
 void mp_hal_disable_all_interrupts(void) {
diff --git a/atmel-samd/supervisor/port.c b/atmel-samd/supervisor/port.c
index 998ad59a4..4ff5d0e1d 100644
--- a/atmel-samd/supervisor/port.c
+++ b/atmel-samd/supervisor/port.c
@@ -89,8 +89,6 @@ safe_mode_t port_init(void) {
 
     init_mcu();
 
-    delay_init(SysTick);
-
     board_init();
 
     // Configure millisecond timer initialization.
diff --git a/atmel-samd/tick.c b/atmel-samd/tick.c
index 1828341e5..c34f1d2af 100644
--- a/atmel-samd/tick.c
+++ b/atmel-samd/tick.c
@@ -1,24 +1,40 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
+ *
+ * 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 "tick.h"
 
-#include <peripheral_clk_config.h>
-
-#include "hal/include/hal_timer.h"
-#include "hpl/pm/hpl_pm_base.h"
-#include "hpl/tc/hpl_tc_base.h"
-#include "hpl/gclk/hpl_gclk_base.h"
-#include "include/component/gclk.h"
+#include "peripheral_clk_config.h"
 
 #include "supervisor/shared/autoreload.h"
-
-#include "tick.h"
+#include "shared-bindings/microcontroller/Processor.h"
 
 // Global millisecond tick count
 volatile uint64_t ticks_ms = 0;
 
-struct timer_descriptor ms_timer;
-//static struct timer_task task;
-
-void timer_tick(const struct timer_task *const timer_task) {
+void SysTick_Handler(void) {
     // SysTick interrupt handler called when the SysTick timer reaches zero
     // (every millisecond).
     ticks_ms += 1;
@@ -29,18 +45,20 @@ void timer_tick(const struct timer_task *const timer_task) {
 }
 
 void tick_init() {
-    #ifdef SAMD21
-    _pm_enable_bus_clock(PM_BUS_APBC, TC5);
-    #endif
-    // _gclk_enable_channel(TC5_GCLK_ID, GCLK_SOURCE_DFLL48M);
-
-    // timer_init(&ms_timer, TC5, _tc_get_timer());
+    uint32_t ticks_per_ms = common_hal_mcu_processor_get_frequency() / 1000;
+    SysTick_Config(ticks_per_ms);
+    NVIC_EnableIRQ(SysTick_IRQn);
+}
 
-    // timer_set_clock_cycles_per_tick(&ms_timer, 48000000 / 1000 - 1);
-    // task.cb       = timer_tick;
-    // task.interval = 1;
-    // task.mode     = TIMER_TASK_REPEAT;
-    // timer_add_task(&ms_timer, &task);
-    //
-    // timer_start(&ms_timer);
+void tick_delay(uint32_t us) {
+    uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
+    uint32_t us_between_ticks = SysTick->VAL / ticks_per_us;
+    uint64_t start_ms = ticks_ms;
+    while (us > 1000) {
+        while (ticks_ms == start_ms) {}
+        us -= us_between_ticks;
+        start_ms = ticks_ms;
+        us_between_ticks = 1000;
+    }
+    while (SysTick->VAL > ((1000 - us) * ticks_per_us)) {}
 }
diff --git a/atmel-samd/tick.h b/atmel-samd/tick.h
index f842fd285..a987ff7ad 100644
--- a/atmel-samd/tick.h
+++ b/atmel-samd/tick.h
@@ -34,4 +34,6 @@ extern struct timer_descriptor ms_timer;
 
 void tick_init(void);
 
+void tick_delay(uint32_t us);
+
 #endif  // MICROPY_INCLUDED_ATMEL_SAMD_TICK_H