Add fuction to set timer frequency.

arch/arm/src/stm32l4/stm32l4_tim.c

@@ -270,6 +270,8 @@ static void stm32l4_tim_dumpregs(FAR struct stm32l4_tim_dev_s *dev);
 
 static int stm32l4_tim_setmode(FAR struct stm32l4_tim_dev_s *dev,
                                enum stm32l4_tim_mode_e mode);
+static int stm32l4_tim_setfreq(FAR struct stm32l4_tim_dev_s *dev,
+                              uint32_t freq);
 static int stm32l4_tim_setclock(FAR struct stm32l4_tim_dev_s *dev,
                                 uint32_t freq);
 static uint32_t  stm32l4_tim_getclock(FAR struct stm32l4_tim_dev_s *dev);
@@ -298,7 +300,10 @@ static int stm32l4_tim_checkint(FAR struct stm32l4_tim_dev_s *dev, int source);
 
 static const struct stm32l4_tim_ops_s stm32l4_tim_ops =
 {
+  .enable     = stm32l4_tim_enable,
+  .disable    = stm32l4_tim_disable,
   .setmode    = stm32l4_tim_setmode,
+  .setfreq    = stm32l4_tim_setfreq,
   .setclock   = stm32l4_tim_setclock,
   .getclock   = stm32l4_tim_getclock,
   .setperiod  = stm32l4_tim_setperiod,
@@ -312,8 +317,6 @@ static const struct stm32l4_tim_ops_s stm32l4_tim_ops =
   .disableint = stm32l4_tim_disableint,
   .ackint     = stm32l4_tim_ackint,
   .checkint   = stm32l4_tim_checkint,
-  .enable     = stm32l4_tim_enable,
-  .disable    = stm32l4_tim_disable,
   .dump_regs  = stm32l4_tim_dumpregs,
 };
 
@@ -689,6 +692,166 @@ static int stm32l4_tim_setmode(FAR struct stm32l4_tim_dev_s *dev,
   return OK;
 }
 
+/************************************************************************************
+ * Name: stm32l4_tim_setfreq
+ ************************************************************************************/
+
+static int stm32l4_tim_setfreq(FAR struct stm32l4_tim_dev_s *dev,
+                              uint32_t freq)
+{
+  uint32_t freqin;
+  int prescaler;
+  uint32_t reload;
+  uint32_t timclk;
+
+  DEBUGASSERT(dev != NULL);
+
+  /* Disable Timer? */
+
+  if (freq == 0)
+    {
+      stm32l4_tim_disable(dev);
+      return 0;
+    }
+
+  /* Get the input clock frequency for this timer.  These vary with
+   * different timer clock sources, MCU-specific timer configuration, and
+   * board-specific clock configuration.  The correct input clock frequency
+   * must be defined in the board.h header file.
+   */
+
+  switch (((struct stm32l4_tim_priv_s *)dev)->base)
+    {
+#ifdef CONFIG_STM32L4_TIM1
+      case STM32L4_TIM1_BASE:
+        freqin = BOARD_TIM1_FREQUENCY;
+        break;
+#endif
+
+#ifdef CONFIG_STM32L4_TIM2
+      case STM32L4_TIM2_BASE:
+        freqin = BOARD_TIM2_FREQUENCY;
+        break;
+#endif
+
+#ifdef CONFIG_STM32L4_TIM3
+      case STM32L4_TIM3_BASE:
+        freqin = BOARD_TIM3_FREQUENCY;
+        break;
+#endif
+
+#ifdef CONFIG_STM32L4_TIM4
+      case STM32L4_TIM4_BASE:
+        freqin = BOARD_TIM4_FREQUENCY;
+        break;
+#endif
+
+#ifdef CONFIG_STM32L4_TIM5
+      case STM32L4_TIM5_BASE:
+        freqin = BOARD_TIM5_FREQUENCY;
+        break;
+#endif
+
+#ifdef CONFIG_STM32L4_TIM6
+      case STM32L4_TIM6_BASE:
+        freqin = BOARD_TIM6_FREQUENCY;
+        break;
+#endif
+
+#ifdef CONFIG_STM32L4_TIM7
+      case STM32L4_TIM7_BASE:
+        freqin = BOARD_TIM7_FREQUENCY;
+        break;
+#endif
+
+#ifdef CONFIG_STM32L4_TIM8
+      case STM32L4_TIM8_BASE:
+        freqin = BOARD_TIM8_FREQUENCY;
+        break;
+#endif
+
+#ifdef CONFIG_STM32L4_TIM15
+      case STM32L4_TIM15_BASE:
+        freqin = BOARD_TIM15_FREQUENCY;
+        break;
+#endif
+#ifdef CONFIG_STM32L4_TIM16
+      case STM32L4_TIM16_BASE:
+        freqin = BOARD_TIM16_FREQUENCY;
+        break;
+#endif
+
+#ifdef CONFIG_STM32L4_TIM17
+      case STM32L4_TIM17_BASE:
+        freqin = BOARD_TIM17_FREQUENCY;
+        break;
+#endif
+
+      default:
+        return -EINVAL;
+    }
+
+  /* Select a pre-scaler value for this timer using the input clock frequency.
+   *
+   * Calculate optimal values for the timer prescaler and for the timer
+   * reload register.  If freq is the desired frequency, then
+   *
+   *   reload = timclk / freq
+   *   reload = (pclck / prescaler) / freq
+   *
+   * There are many solutions to do this, but the best solution will be the
+   * one that has the largest reload value and the smallest prescaler value.
+   * That is the solution that should give us the most accuracy in the timer
+   * control.  Subject to:
+   *
+   *   0 <= prescaler  <= 65536
+   *   1 <= reload <= 65535
+   *
+   * So ( prescaler = pclck / 65535 / freq ) would be optimal.
+   */
+
+  prescaler = (freqin / freq + 65534) / 65535;
+
+  /* We need to decrement value for '1', but only if that will not to
+   * cause underflow.
+   */
+
+  if (prescaler < 1)
+    {
+      awarn("WARNING: Prescaler underflowed.\n");
+      prescaler = 1;
+    }
+
+  /* Check for overflow as well. */
+
+  if (prescaler > 65536)
+    {
+      awarn("WARNING: Prescaler overflowed.\n");
+      prescaler = 65536;
+    }
+
+  timclk = freqin / prescaler;
+
+  reload = timclk / freq;
+  if (reload < 1)
+    {
+      awarn("WARNING: Reload value underflowed.\n");
+      reload = 1;
+    }
+  else if (reload > 65535)
+    {
+      awarn("WARNING: Reload value overflowed.\n");
+      reload = 65535;
+    }
+
+  /* Set the reload and prescaler values */
+
+  stm32l4_putreg16(dev, STM32L4_GTIM_PSC_OFFSET, prescaler - 1);
+  stm32l4_putreg16(dev, STM32L4_GTIM_ARR_OFFSET, reload);
+
+  return (timclk / reload);
+}
+
 /************************************************************************************
  * Name: stm32l4_tim_setclock
  ************************************************************************************/

arch/arm/src/stm32l4/stm32l4_tim.h

@@ -58,6 +58,7 @@
 /* Helpers *******************************************************************/
 
 #define STM32L4_TIM_SETMODE(d,mode)       ((d)->ops->setmode(d,mode))
+#define STM32L4_TIM_SETFREQ(d,freq)       ((d)->ops->setfreq(d,freq))
 #define STM32L4_TIM_SETCLOCK(d,freq)      ((d)->ops->setclock(d,freq))
 #define STM32L4_TIM_GETCLOCK(d)           ((d)->ops->getclock(d))
 #define STM32L4_TIM_SETPERIOD(d,period)   ((d)->ops->setperiod(d,period))
@@ -173,8 +174,11 @@ struct stm32l4_tim_ops_s
 {
   /* Basic Timers */
 
+  void (*enable)(FAR struct stm32l4_tim_dev_s *dev);
+  void (*disable)(FAR struct stm32l4_tim_dev_s *dev);
   int  (*setmode)(FAR struct stm32l4_tim_dev_s *dev,
                   enum stm32l4_tim_mode_e mode);
+  int  (*setfreq)(FAR struct stm32l4_tim_dev_s *dev, uint32_t freq);
   int  (*setclock)(FAR struct stm32l4_tim_dev_s *dev, uint32_t freq);
   uint32_t (*getclock)(FAR struct stm32l4_tim_dev_s *dev);
   void (*setperiod)(FAR struct stm32l4_tim_dev_s *dev, uint32_t period);
@@ -197,8 +201,9 @@ struct stm32l4_tim_ops_s
   void (*disableint)(FAR struct stm32l4_tim_dev_s *dev, int source);
   void (*ackint)(FAR struct stm32l4_tim_dev_s *dev, int source);
   int  (*checkint)(FAR struct stm32l4_tim_dev_s *dev, int source);
-  void (*enable)(FAR struct stm32l4_tim_dev_s *dev);
+
-  void (*disable)(FAR struct stm32l4_tim_dev_s *dev);
+  /* Debug */
+
   void (*dump_regs)(FAR struct stm32l4_tim_dev_s *dev);
 };
 

boards/arm/stm32l4/nucleo-l432kc/src/stm32_spwm.c

@@ -359,7 +359,6 @@ static int spwm_tim6_setup(FAR struct spwm_s *spwm)
 {
   FAR struct stm32l4_tim_dev_s *tim = NULL;
   uint64_t freq = 0;
-  uint32_t per = 0;
   int ret = OK;
 
   /* Get TIM6 interface */
@@ -380,18 +379,8 @@ static int spwm_tim6_setup(FAR struct spwm_s *spwm)
    */
 
   freq = spwm->samples * spwm->waveform_freq;
-  per = BOARD_TIM6_FREQUENCY / freq;
-  if (per > 0xffff)
-    {
-      printf("ERROR: can not achieve TIM6 frequency\n");
-      ret = -1;
-      goto errout;
-    }
 
-  /* TODO: TIM_SETFREQ */
+  STM32L4_TIM_SETFREQ(tim, freq);
-
-  STM32L4_TIM_SETCLOCK(tim, BOARD_TIM6_FREQUENCY);
-  STM32L4_TIM_SETPERIOD(tim, per);
   STM32L4_TIM_ENABLE(tim);
 
   /* Attach TIM6 ram vector */