Use HAL suspend/resume timer procs rather than atomic.

- Preparation for removing begin/end atomic.

libraries/AP_ADC/AP_ADC_ADS7844.cpp

@@ -180,13 +180,13 @@ float AP_ADC_ADS7844::Ch(uint8_t ch_num)
     // ensure we have at least one value
     while (_count[ch_num] == 0) /* noop */;
 
-    // grab the value with interrupts disabled, and clear the count
-    hal.scheduler->begin_atomic();
+    // grab the value with timer procs disabled, and clear the count
+    hal.scheduler->suspend_timer_procs();
     count = _count[ch_num];
     sum   = _sum[ch_num];
     _count[ch_num] = 0;
     _sum[ch_num]   = 0;
-    hal.scheduler->end_atomic();
+    hal.scheduler->resume_timer_procs();
 
     return ((float)sum)/count;
 }
@@ -221,8 +221,8 @@ uint32_t AP_ADC_ADS7844::Ch6(const uint8_t *channel_numbers, float *result)
         while (_count[channel_numbers[i]] == 0) /* noop */;
     }
 
-    // grab the values with interrupts disabled, and clear the counts
-    hal.scheduler->begin_atomic();
+    // grab the values with timer procs disabled, and clear the counts
+    hal.scheduler->suspend_timer_procs();
     for (i=0; i<6; i++) {
         count[i] = _count[channel_numbers[i]];
         sum[i]   = _sum[channel_numbers[i]];
@@ -235,7 +235,7 @@ uint32_t AP_ADC_ADS7844::Ch6(const uint8_t *channel_numbers, float *result)
     uint32_t ret = _ch6_last_sample_time_micros - _ch6_delta_time_start_micros;
     _ch6_delta_time_start_micros = _ch6_last_sample_time_micros;
 
-    hal.scheduler->end_atomic();
+    hal.scheduler->resume_timer_procs();
 
     // calculate averages. We keep this out of the cli region
     // to prevent us stalling the ISR while doing the

libraries/AP_Baro/AP_Baro_MS5611.cpp

@@ -289,15 +289,17 @@ uint8_t AP_Baro_MS5611::read()
     if (updated) {
         uint32_t sD1, sD2;
         uint8_t d1count, d2count;
-        // we need to disable interrupts to access
-        // _s_D1 and _s_D2 as they are not atomic
-        hal.scheduler->begin_atomic();
+
+        // Suspend timer procs because these variables are written to
+        // in "_update".
+        hal.scheduler->suspend_timer_procs();
         sD1 = _s_D1; _s_D1 = 0;
         sD2 = _s_D2; _s_D2 = 0;
         d1count = _d1_count; _d1_count = 0;
         d2count = _d2_count; _d2_count = 0;
         _updated = false;
-        hal.scheduler->end_atomic();
+        hal.scheduler->resume_timer_procs();
+
         if (d1count != 0) {
             D1 = ((float)sD1) / d1count;
         }

libraries/AP_InertialSensor/AP_InertialSensor_MPU6000.cpp

@@ -264,8 +264,8 @@ bool AP_InertialSensor_MPU6000::update( void )
     // wait for at least 1 sample
     wait_for_sample();
 
-    // disable interrupts for mininum time
-    hal.scheduler->begin_atomic();
+    // disable timer procs for mininum time
+    hal.scheduler->suspend_timer_procs();
     for (int i=0; i<7; i++) {
         sum[i] = _sum[i];
         _sum[i] = 0;
@@ -277,7 +277,7 @@ bool AP_InertialSensor_MPU6000::update( void )
     // record sample time
     _delta_time_micros = _last_sample_time_micros - _delta_time_start_micros;
     _delta_time_start_micros = _last_sample_time_micros;
-    hal.scheduler->end_atomic();
+    hal.scheduler->resume_timer_procs();
 
     count_scale = 1.0 / count;