HAL_ChibiOS: enable fmu out 7 and 8 for fmuv5

these are exposed on the Pixhawk4

libraries/AP_HAL_ChibiOS/hwdef/fmuv5/hwdef.dat

@@ -162,8 +162,12 @@ PE11 TIM1_CH2 TIM1 PWM(3) GPIO(52)
 PE9  TIM1_CH1 TIM1 PWM(4) GPIO(53)
 PD13 TIM4_CH2 TIM4 PWM(5) GPIO(54)
 PD14 TIM4_CH3 TIM4 PWM(6) GPIO(55)
-#PH6  TIM12_CH1 TIM12 PWM(7) GPIO(56)
-#PH9  TIM12_CH2 TIM12 PWM(8) GPIO(57)
+# we need to disable DMA on the last 2 FMU channels
+# as timer 12 doesn't have a TIMn_UP DMA option
+PH6  TIM12_CH1 TIM12 PWM(7) GPIO(56) NODMA
+PH9  TIM12_CH2 TIM12 PWM(8) GPIO(57) NODMA
+
+define BOARD_PWM_COUNT_DEFAULT 8
 
 # PWM output for buzzer
 PE5 TIM9_CH1 TIM9 GPIO(77) ALARM

libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py

@@ -774,10 +774,10 @@ def write_PWM_config(f):
         for p in pwm_out:
             if p.type != t:
                 continue
-            chan_str = p.label[7]
+            chan_str = p.label[-1]
             is_complementary = p.label[-1] == 'N';
             if not is_int(chan_str):
-                error("Bad channel for PWM %s" % p)
+                error("Bad channel for PWM %s chan_str=%s" % (p, chan_str))
             chan = int(chan_str)
             if chan not in [1, 2, 3, 4]:
                 error("Bad channel number %u for PWM %s" % (chan, p))
@@ -1058,7 +1058,7 @@ def build_peripheral_list():
             elif not p.has_extra('ALARM') and not p.has_extra('RCININT'):
                 # get the TIMn_UP DMA channels for DShot
                 label = type + '_UP'
-                if not label in peripherals:
+                if not label in peripherals and not p.has_extra('NODMA'):
                     peripherals.append(label)
         done.add(type)
     return peripherals