counter: mchp_xec: update driver for counter tests

The counter driver tests have been updated so the driver needs
to be updated too.

() Test expects a free running counter.
() Test expects any alarms cannot be set beyond the top value.
() Also, the counter only triggers interrupts when counter reaches
   zero (as configured as counting down), it can be do relative
   alarms. So return -ENOTSUP when absolute alarms are requested.
() The test expects the callback to be removed once alarm is
   triggered. Implement this too.

Signed-off-by: Daniel Leung <[email protected]>

Author: dcpleung

drivers/counter/counter_mchp_xec.c

@@ -4,12 +4,29 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+/**
+ * @file
+ * @brief Microchip XEC Counter driver
+ *
+ * This is the driver for the 16/32-bit counters on the Microchip SoCs.
+ *
+ * Notes:
+ * - The counters are running in down counting mode.
+ * - Interrupts are triggered (if enabled) when the counter
+ *   reaches zero.
+ * - These are not free running counters where there are separate
+ *   compare values for interrupts. When setting single shot alarms,
+ *   the counter values are changed so that interrupts are triggered
+ *   when the counters reach zero.
+ */
+
 #include <logging/log.h>
 LOG_MODULE_REGISTER(counter_mchp_xec, CONFIG_COUNTER_LOG_LEVEL);
 
 #include <counter.h>
 #include <soc.h>
 #include <errno.h>
+#include <stdbool.h>
 
 struct counter_xec_config {
 	struct counter_config_info info;
@@ -46,7 +63,7 @@ static int counter_xec_start(struct device *dev)
 		return -EALREADY;
 	}
 
-	counter->CTRL |= MCHP_BTMR_CTRL_ENABLE;
+	counter->CTRL |= (MCHP_BTMR_CTRL_ENABLE | MCHP_BTMR_CTRL_START);
 
 	LOG_DBG("%p Counter started", dev);
 
@@ -72,7 +89,7 @@ static int counter_xec_stop(struct device *dev)
 	counter->CTRL = reg;
 
 	counter->IEN = MCHP_BTMR_INTDIS;
-	counter->CNT = 0;
+	counter->CNT = counter->PRLD;
 
 	LOG_DBG("%p Counter stopped", dev);
 
@@ -90,49 +107,40 @@ static int counter_xec_set_alarm(struct device *dev, u8_t chan_id,
 				 const struct counter_alarm_cfg *alarm_cfg)
 {
 	BTMR_Type *counter = COUNTER_XEC_REG_BASE(dev);
-	const struct counter_xec_config *counter_cfg = COUNTER_XEC_CONFIG(dev);
 	struct counter_xec_data *data = COUNTER_XEC_DATA(dev);
-	u32_t ticks;
 
 	if (chan_id != 0) {
 		LOG_ERR("Invalid channel id %u", chan_id);
 		return -ENOTSUP;
 	}
 
-	if (!(counter->CTRL & MCHP_BTMR_CTRL_ENABLE)) {
-		return -EIO;
+	/* Interrupts are only triggered when the counter reaches 0.
+	 * So only relative alarms are supported.
+	 */
+	if (alarm_cfg->flags & COUNTER_ALARM_CFG_ABSOLUTE) {
+		return -ENOTSUP;
 	}
 
-	if (counter->CTRL & MCHP_BTMR_CTRL_START) {
+	if (data->alarm_cb != NULL) {
 		return -EBUSY;
 	}
 
 	if (!alarm_cfg->callback) {
 		return -EINVAL;
 	}
 
-	ticks = alarm_cfg->ticks;
-
-	if (counter_cfg->info.max_top_value == UINT16_MAX) {
-		if (ticks > UINT16_MAX) {
-			return -EINVAL;
-		}
-	}
-
-	if (!(alarm_cfg->flags & COUNTER_ALARM_CFG_ABSOLUTE)) {
-		u64_t abs_cnt = ticks + counter->CNT;
-
-		ticks = (u32_t) abs_cnt % counter_cfg->info.max_top_value;
+	if (alarm_cfg->ticks > counter->PRLD) {
+		return -EINVAL;
 	}
 
-	counter->CNT = ticks;
+	counter->CNT = alarm_cfg->ticks;
 
 	data->alarm_cb = alarm_cfg->callback;
 	data->user_data = alarm_cfg->user_data;
 
 	counter->IEN = MCHP_BTMR_INTEN;
 
-	LOG_DBG("%p Counter alarm set to %u ticks", dev, ticks);
+	LOG_DBG("%p Counter alarm set to %u ticks", dev, alarm_cfg->ticks);
 
 	counter->CTRL |= MCHP_BTMR_CTRL_START;
 
@@ -242,14 +250,23 @@ static void counter_xec_isr(struct device *dev)
 	BTMR_Type *counter = COUNTER_XEC_REG_BASE(dev);
 	const struct counter_xec_config *counter_cfg = COUNTER_XEC_CONFIG(dev);
 	struct counter_xec_data *data = COUNTER_XEC_DATA(dev);
+	counter_alarm_callback_t alarm_cb;
+	void *user_data;
 
 	counter->STS = MCHP_BTMR_STS_ACTIVE;
 	MCHP_GIRQ_SRC(counter_cfg->girq_id) = BIT(counter_cfg->girq_bit);
 
 	LOG_DBG("%p Counter ISR", dev);
 
 	if (data->alarm_cb) {
-		data->alarm_cb(dev, 0, counter->CNT, data->user_data);
+		/* Alarm is one-shot, so disable interrupt and callback */
+		counter->IEN = MCHP_BTMR_INTDIS;
+
+		alarm_cb = data->alarm_cb;
+		data->alarm_cb = NULL;
+		user_data = data->user_data;
+
+		alarm_cb(dev, 0, counter->CNT, user_data);
 	} else if (data->top_cb) {
 		data->top_cb(dev, data->user_data);
 	}
@@ -278,6 +295,10 @@ static int counter_xec_init(struct device *dev)
 	counter->CTRL |= (counter_cfg->prescaler << MCHP_BTMR_CTRL_PRESCALE_POS) &
 		MCHP_BTMR_CTRL_PRESCALE_MASK;
 
+	/* Set preload and actually pre-load the counter */
+	counter->PRLD = counter_cfg->info.max_top_value;
+	counter->CNT = counter_cfg->info.max_top_value;
+
 	MCHP_GIRQ_ENSET(counter_cfg->girq_id) = BIT(counter_cfg->girq_bit);
 
 	counter_cfg->config_func();