drivers: add functions to support TC external trigger

Add function tcd_waveform_enable_exteral_trigger() to enable external
event trigger.
Add function tc_get_config() to retrieve TC_CMR.

Signed-off-by: LI BIN <bin.li@microchip.com>

drivers/peripherals/tc.c

@@ -103,6 +103,17 @@ void tc_configure(Tc *tc, uint32_t channel, uint32_t mode)
 	ch->TC_CMR = mode;
 }
 
+uint32_t tc_get_config(Tc *tc, uint32_t channel)
+{
+	TcChannel* ch;
+
+	assert(channel < ARRAY_SIZE(tc->TC_CHANNEL));
+
+	ch = &tc->TC_CHANNEL[channel];
+	/*  Get mode */
+	return ch->TC_CMR;
+}
+
 void tc_start(Tc *tc, uint32_t channel)
 {
 	TcChannel *ch;

drivers/peripherals/tc.h

@@ -69,6 +69,15 @@
  */
 extern void tc_configure (Tc* tc, uint32_t channel, uint32_t mode);
 
+/**
+ * \brief Get TC configures
+ *
+ * Return TC_CMR value. 
+ * \param tc  Pointer to a Tc instance.
+ * \param channel Channel number.
+ */
+extern uint32_t tc_get_config(Tc *tc, uint32_t channel);
+
 /**
  * \brief Reset and Start the TC Channel
  *

drivers/peripherals/tcd.c

@@ -190,6 +190,22 @@ int tcd_configure_waveform(struct _tcd_desc* desc, uint32_t min_timer_freq, uint
 	return chan_freq / rc;
 }
 
+/**
+ * \brief Enable waveform with external trigger
+ * \param desc   TC driver descriptor
+ */
+int tcd_waveform_enable_exteral_trigger(struct _tcd_desc* desc)
+{
+	uint32_t config;
+
+	config = tc_get_config(desc->addr, desc->channel);
+	if ((config & TC_CMR_WAVE) != TC_CMR_WAVE)
+		return -EINVAL;
+	config |= TC_CMR_ETRGEDG_RISING | TC_CMR_ABETRG | TC_CMR_ENETRG;
+	tc_configure(desc->addr, desc->channel, config);
+	return 0;
+}
+
 int tcd_configure_capture(struct _tcd_desc* desc, uint32_t frequency, struct _buffer* buffer)
 {
 	uint32_t tc_id = get_tc_id_from_addr(desc->addr, desc->channel);

drivers/peripherals/tcd.h

@@ -123,6 +123,12 @@ extern int tcd_configure_waveform(
 		uint32_t frequency,
 		uint16_t duty_cycle);
 
+/**
+ * \brief Enable waveform with external trigger
+ * \param desc   TC driver descriptor
+ */
+extern int tcd_waveform_enable_exteral_trigger(struct _tcd_desc* desc);
+
 /**
  * \brief Configure a timer to capture a signal
  * \param frequency   Frequency of the timer