Fastmodel: add HAL low-power ticker implementation

Author: Qinghao Shi

targets/TARGET_ARM_FM/TARGET_FVP_MPS2/lp_ticker.c

@@ -0,0 +1,120 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2018 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <stddef.h>
+#include "lp_ticker_api.h"
+#include "PeripheralNames.h"
+
+#define LP_TICKER_INTERRUPT   CMSDK_TIMER0
+#define LP_TICKER_COUNTER     CMSDK_TIMER1
+#define LP_TICKER_TIMER_IRQn  TIMER0_IRQn
+
+
+/*  mbed OS HAL API defined lp_ticker as an increment ticker
+ *  MPS2 platform provided in SSE-200 are decrement tickers
+ *  with interrupt fired counter reaches 0.
+ *
+ *  So 2 Timers are used to construct mbed OS HAL low power ticker.
+ *
+ *  TIMER0 is for generating interrupts
+ *  and TIMER0 will turned off when it is generating interrupts
+ *
+ *  TIMER1 is for counting, and returns inverted binary when read from it
+ *  Because TIMER1 is running at the speed of 25Mhz, it need to be shift by 10,
+ *  in order to meet mbed HAL lp_ticker definitions
+ *
+ */
+
+static int lp_ticker_inited = 0;
+
+void lp_ticker_internal_handler(void)
+{
+    LP_TICKER_INTERRUPT->CTRL &= ~CMSDK_TIMER_CTRL_IRQEN_Msk;
+    LP_TICKER_INTERRUPT->CTRL &= ~CMSDK_TIMER_CTRL_EN_Msk;
+    lp_ticker_irq_handler();
+}
+
+
+void lp_ticker_init(void)
+{
+    if (lp_ticker_inited) {
+        lp_ticker_disable_interrupt();
+        return;
+    }
+
+    LP_TICKER_COUNTER->CTRL   = 0x0ul;
+    LP_TICKER_INTERRUPT->CTRL = 0x0ul;
+
+    LP_TICKER_COUNTER->RELOAD   = 0xFFFFFFFFul;
+    LP_TICKER_INTERRUPT->RELOAD = 0xFFFFFFFFul;
+
+    LP_TICKER_COUNTER->CTRL |= CMSDK_TIMER_CTRL_EN_Msk;
+
+    NVIC_SetVector(LP_TICKER_TIMER_IRQn, (uint32_t)lp_ticker_internal_handler);
+    lp_ticker_inited = 1;
+}
+
+void lp_ticker_free(void)
+{
+    LP_TICKER_COUNTER->CTRL &= ~CMSDK_TIMER_CTRL_EN_Msk;
+    lp_ticker_disable_interrupt();
+    lp_ticker_inited = 0;
+}
+
+uint32_t lp_ticker_read()
+{
+    return (~LP_TICKER_COUNTER->VALUE) >> 10;
+}
+
+void lp_ticker_set_interrupt(timestamp_t timestamp)
+{
+    uint32_t delta = (timestamp << 10) - (~LP_TICKER_COUNTER->VALUE);
+
+    LP_TICKER_INTERRUPT->CTRL &= ~CMSDK_TIMER_CTRL_EN_Msk;
+    LP_TICKER_INTERRUPT->RELOAD = delta;
+    LP_TICKER_INTERRUPT->CTRL |= CMSDK_TIMER_CTRL_IRQEN_Msk;
+    LP_TICKER_INTERRUPT->CTRL |= CMSDK_TIMER_CTRL_EN_Msk;
+
+    NVIC_EnableIRQ(LP_TICKER_TIMER_IRQn);
+}
+
+void lp_ticker_fire_interrupt(void)
+{
+    NVIC_EnableIRQ(LP_TICKER_TIMER_IRQn);
+    NVIC_SetPendingIRQ(LP_TICKER_TIMER_IRQn);
+}
+
+void lp_ticker_disable_interrupt(void)
+{
+    LP_TICKER_INTERRUPT->CTRL &= ~CMSDK_TIMER_CTRL_IRQEN_Msk;
+    LP_TICKER_INTERRUPT->CTRL &= ~CMSDK_TIMER_CTRL_EN_Msk;
+    NVIC_DisableIRQ(LP_TICKER_TIMER_IRQn);
+}
+
+void lp_ticker_clear_interrupt(void)
+{
+    LP_TICKER_INTERRUPT->INTCLEAR = CMSDK_TIMER_INTCLEAR_Msk;
+}
+
+const ticker_info_t *lp_ticker_get_info(void)
+{
+    static const ticker_info_t info = {
+        24414, // 10 stages scaled from 25MHz (dived by 1024)
+        22     // 22 bit counter
+    };
+    return &info;
+}
+
+