pwm: add PWM overwrite under CONFIG_PWM_OVERWRITE option

Generic drivers shoud not use architecture related config options like
CONFIG_SAMV7_PWM. This commit adds PWM pin overwrite under generic
configuration option CONFIG_PWM_OVERWRITE.

Now the overwrite can be used on other architectures as well or can be
completely disabled for SAMv7.

Signed-off-by: Michal Lenc <michallenc@seznam.cz>

arch/arm/src/samv7/Kconfig

@@ -313,6 +313,7 @@ config SAMV7_PWM
 	bool
 	default n
 	select ARCH_HAVE_PWM_MULTICHAN
+	select ARCH_HAVE_PWM_OVERWRITE
 
 config SAMV7_HAVE_SDRAMC
 	bool

arch/arm/src/samv7/sam_pwm.c

@@ -449,7 +449,9 @@ static int pwm_start(struct pwm_lowerhalf_s *dev,
                      const struct pwm_info_s *info)
 {
   struct sam_pwm_s *priv = (struct sam_pwm_s *)dev;
+#ifdef CONFIG_PWM_OVERWRITE
   uint32_t regval;
+#endif
 
 #ifdef CONFIG_PWM_MULTICHAN
       for (int i = 0; i < PWM_NCHANNELS; i++)
@@ -474,6 +476,7 @@ static int pwm_start(struct pwm_lowerhalf_s *dev,
               pwm_set_output(dev, priv->channels[index - 1].channel,
                              info->channels[i].duty);
 
+#ifdef CONFIG_PWM_OVERWRITE
               if (info->channels[i].ch_outp_ovrwr)
                 {
                   regval = pwm_getreg(priv, SAMV7_PWM_OOV);
@@ -491,6 +494,7 @@ static int pwm_start(struct pwm_lowerhalf_s *dev,
                   regval = (1 << priv->channels[i].channel);
                   pwm_putreg(priv, SAMV7_PWM_OSC, regval);
                 }
+#endif
             }
         }
 #else

drivers/timers/Kconfig

@@ -9,6 +9,10 @@ config ARCH_HAVE_PWM_PULSECOUNT
 	bool
 	default n
 
+config ARCH_HAVE_PWM_OVERWRITE
+	bool
+	default n
+
 config ARCH_HAVE_PWM_MULTICHAN
 	bool
 	default n
@@ -32,6 +36,16 @@ config PWM_PULSECOUNT
 		hardware will support a fixed pulse count, then this configuration
 		should be set to enable the capability.
 
+config PWM_OVERWRITE
+	bool "PWM Overwrite Support"
+	default n
+	depends on ARCH_HAVE_PWM_OVERWRITE
+	---help---
+		Some hardware will support generation of a pin overwrite with 0 or
+		1 without the need to wait for an end of cycle. The overwrite is
+		controlled from an application level the same way duty cycle or
+		frequency is modified.
+
 config PWM_MULTICHAN
 	bool "PWM Multiple Output Channel Support"
 	default n

include/nuttx/timers/pwm.h

@@ -120,7 +120,7 @@
 struct pwm_chan_s
 {
   ub16_t duty;
-#ifdef CONFIG_SAMV7_PWM
+#ifdef CONFIG_PWM_OVERWRITE
   bool ch_outp_ovrwr;
   bool ch_outp_ovrwr_val;
 #endif