MLECO-2948: Minor refactoring for platform modules.

Reducing dependency on cmsis-device sources as these will
be removed under MLECO-2944. Also, starting to refactor
to allow HAL to drop NPU and TA init routines - this will
happen in future CRs.

Added platform driver for native, and subsequent patches
will attempt to get rid of the HAL "profile" specific
sources and allow platform stub implementations at a level
below HAL. This will allow platforms drivers to only
override the range of functions that they actually want to
implement and will fall back on stubs for the rest. In this
CR only "utils" have been removed.

Change-Id: I09b4a28e20847a07a956c818c6f47c74aab89063
diff --git a/source/hal/platform/simple/source/timer_simple_platform.c b/source/hal/platform/simple/source/timer_simple_platform.c
index 4bcd07b..3d28261 100644
--- a/source/hal/platform/simple/source/timer_simple_platform.c
+++ b/source/hal/platform/simple/source/timer_simple_platform.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021 Arm Limited. All rights reserved.
+ * Copyright (c) 2021-2022 Arm Limited. All rights reserved.
  * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -16,11 +16,26 @@
  */
 #include "timer_simple_platform.h"
 
-#include "irqs.h"
-#include "log_macros.h"
+#include "log_macros.h"     /* Logging macros */
+#include "cmsis.h"          /* For CPU related defintiions */
 
 #include <inttypes.h>
 
+static uint64_t cpu_cycle_count = 0;    /* 64-bit cpu cycle counter */
+extern uint32_t SystemCoreClock;        /* Expected to come from the cmsis-device lib */
+
+/**
+ * @brief   Gets the system tick triggered cycle counter for the CPU.
+ * @return  64-bit counter value.
+ **/
+static uint64_t Get_SysTick_Cycle_Count(void);
+
+/**
+ * SysTick initialisation
+ */
+static int Init_SysTick(void);
+
+
 base_time_counter get_time_counter(void)
 {
     base_time_counter t = {
@@ -56,3 +71,53 @@
 {
     /* Add any custom requirement for this platform here */
 }
+
+
+void SysTick_Handler(void)
+{
+    /* Increment the cycle counter based on load value. */
+    cpu_cycle_count += SysTick->LOAD + 1;
+}
+
+/**
+ * Gets the current SysTick derived counter value
+ */
+static uint64_t Get_SysTick_Cycle_Count(void)
+{
+    uint32_t systick_val;
+
+    NVIC_DisableIRQ(SysTick_IRQn);
+    systick_val = SysTick->VAL & SysTick_VAL_CURRENT_Msk;
+    NVIC_EnableIRQ(SysTick_IRQn);
+
+    return cpu_cycle_count + (SysTick->LOAD - systick_val);
+}
+
+/**
+ * SysTick initialisation
+ */
+static int Init_SysTick(void)
+{
+    const uint32_t ticks_10ms = SystemCoreClock/100 + 1;
+    int err = 0;
+
+    /* Reset CPU cycle count value. */
+    cpu_cycle_count = 0;
+
+    /* Changing configuration for sys tick => guard from being
+     * interrupted. */
+    NVIC_DisableIRQ(SysTick_IRQn);
+
+    /* SysTick init - this will enable interrupt too. */
+    err = SysTick_Config(ticks_10ms);
+
+    /* Enable interrupt again. */
+    NVIC_EnableIRQ(SysTick_IRQn);
+
+    /* Wait for SysTick to kick off */
+    while (!err && !SysTick->VAL) {
+        __NOP();
+    }
+
+    return err;
+}
\ No newline at end of file