drivers: counter: Update CTimer to fix alarm setting

1. Make sure the relative alarm value is set correctly
2. Add a Kconfig to give user the option of reserving
   a CTimer channel for implementing the set_top_value
   function

Signed-off-by: Mahesh Mahadevan <[email protected]>

drivers/counter/Kconfig.mcux_ctimer

@@ -8,3 +8,11 @@ config COUNTER_MCUX_CTIMER
 	depends on HAS_MCUX_CTIMER
 	help
 	  Enable support for MCUX CTIMER driver.
+
+config COUNTER_MCUX_CTIMER_RESERVE_CHANNEL_FOR_SETTOP
+	bool "reserve a ctimer channel to set the top value"
+	default y
+	depends on COUNTER_MCUX_CTIMER
+	help
+	  This reserves a CTimer channel to set the top value. Without
+	  this the set top value can be set only to the max counter value.

drivers/counter/counter_mcux_ctimer.c

@@ -12,8 +12,12 @@
 #include <zephyr/dt-bindings/clock/mcux_lpc_syscon_clock.h>
 LOG_MODULE_REGISTER(mcux_ctimer, CONFIG_COUNTER_LOG_LEVEL);
 
+#ifdef CONFIG_COUNTER_MCUX_CTIMER_RESERVE_CHANNEL_FOR_SETTOP
 /* One of the CTimer channels is reserved to implement set_top_value API */
 #define NUM_CHANNELS 3
+#else
+#define NUM_CHANNELS 4
+#endif
 
 struct mcux_lpc_ctimer_channel_data {
 	counter_alarm_callback_t alarm_callback;
@@ -70,6 +74,8 @@ static int mcux_lpc_ctimer_get_value(const struct device *dev, uint32_t *ticks)
 static uint32_t mcux_lpc_ctimer_get_top_value(const struct device *dev)
 {
 	const struct mcux_lpc_ctimer_config *config = dev->config;
+
+#ifdef CONFIG_COUNTER_MCUX_CTIMER_RESERVE_CHANNEL_FOR_SETTOP
 	CTIMER_Type *base = config->base;
 
 	/* Return the top value if it has been set, else return the max top value */
@@ -78,18 +84,21 @@ static uint32_t mcux_lpc_ctimer_get_top_value(const struct device *dev)
 	} else {
 		return config->info.max_top_value;
 	}
+#else
+	return config->info.max_top_value;
+#endif
 }
 
 static int mcux_lpc_ctimer_set_alarm(const struct device *dev, uint8_t chan_id,
 				     const struct counter_alarm_cfg *alarm_cfg)
 {
 	const struct mcux_lpc_ctimer_config *config = dev->config;
 	struct mcux_lpc_ctimer_data *data = dev->data;
-
 	uint32_t ticks = alarm_cfg->ticks;
 	uint32_t current = mcux_lpc_ctimer_read(config->base);
+	uint32_t top = mcux_lpc_ctimer_get_top_value(dev);
 
-	if (alarm_cfg->ticks > mcux_lpc_ctimer_get_top_value(dev)) {
+	if (alarm_cfg->ticks > top) {
 		return -EINVAL;
 	}
 
@@ -100,6 +109,9 @@ static int mcux_lpc_ctimer_set_alarm(const struct device *dev, uint8_t chan_id,
 
 	if ((alarm_cfg->flags & COUNTER_ALARM_CFG_ABSOLUTE) == 0) {
 		ticks += current;
+		if (ticks > top) {
+			ticks %= top;
+		}
 	}
 
 	data->channels[chan_id].alarm_callback = alarm_cfg->callback;
@@ -136,6 +148,15 @@ static int mcux_lpc_ctimer_set_top_value(const struct device *dev,
 	const struct mcux_lpc_ctimer_config *config = dev->config;
 	struct mcux_lpc_ctimer_data *data = dev->data;
 
+#ifndef CONFIG_COUNTER_MCUX_CTIMER_RESERVE_CHANNEL_FOR_SETTOP
+	/* Only allow max value when we do not reserve a ctimer channel for setting top value */
+	if (cfg->ticks != config->info.max_top_value) {
+		LOG_ERR("Wrap can only be set to 0x%x",
+			config->info.max_top_value);
+		return -ENOTSUP;
+	}
+#endif
+
 	data->top_callback = cfg->callback;
 	data->top_user_data = cfg->user_data;
 
@@ -148,6 +169,7 @@ static int mcux_lpc_ctimer_set_top_value(const struct device *dev,
 		return -ETIME;
 	}
 
+#ifdef CONFIG_COUNTER_MCUX_CTIMER_RESERVE_CHANNEL_FOR_SETTOP
 	ctimer_match_config_t match_config = { .matchValue = cfg->ticks,
 					       .enableCounterReset = true,
 					       .enableCounterStop = false,
@@ -156,6 +178,7 @@ static int mcux_lpc_ctimer_set_top_value(const struct device *dev,
 					       .enableInterrupt = true };
 
 	CTIMER_SetupMatch(config->base, NUM_CHANNELS, &match_config);
+#endif
 
 	return 0;
 }
@@ -216,9 +239,11 @@ static void mcux_lpc_ctimer_isr(const struct device *dev)
 		}
 	}
 
+#ifdef CONFIG_COUNTER_MCUX_CTIMER_RESERVE_CHANNEL_FOR_SETTOP
 	if (((interrupt_stat & (0x01 << NUM_CHANNELS)) != 0) && data->top_callback) {
 		data->top_callback(dev, data->top_user_data);
 	}
+#endif
 }
 
 static int mcux_lpc_ctimer_init(const struct device *dev)