drivers: i2c: i2c_mspm0g3xxx: add watchdog timer

When the system is crashing, the I2C lines (SDA/SCL) are not being
reset and might stay LOW. To address this issue, we need to ensure that
none of the user i2c driver callbacks (that are doing reads or writes)
are taking longer than CONFIG_I2C_MSPM0G3XXX_WATCHDOG_TIMEOUT. So we
fire a timer before each call. If the callback doesn't finish fast
enough, the watchdog callback will reset the i2c lines, NACK the i2c
message and panic with the CONFIG_MSPM0G3XXX_I2C_WATCHDOG_PANIC_CODE
error code.

The timeout is configured with CONFIG_I2C_MSPM0G3XXX_WATCHDOG_TIMEOUT
The panic error code is configured with
CONFIG_MSPM0G3XXX_I2C_WATCHDOG_PANIC_CODE.

To make sure of this reboot feature, the device tree needs to provide
a reference to a hardware timer. Let's say we want to use timer timg7
as a watchdog:

We need to configure that timer in the dts:

```
&timg7 {
	status = "okay";
	mode = <ONE_SHOT_DOWN>;
	prescaler = <0>;
	divide-ratio = <RATE_1>;
};
```

and then reference in the i2c block:

```
&i2c0 {
	watchdog-timer = <&timg7>;
	extras ...
```

Since we are invoking a software panic on the mcu, make sure to disable
the COREDUMP logging as it will introduce performance penalties and
delay the mcu reboot.

This can be done with:
```
CONFIG_DEBUG_COREDUMP=n
```

Of course for now, the implementation is using a counter timer since
we don't have a mspm0 watchdog.

Signed-off-by: Dimitris Karnikis <[email protected]>

Author: dkarnikis

drivers/i2c/i2c_mspm0g3xxx.c

@@ -6,6 +6,7 @@
 #include <zephyr/kernel.h>
 #include <zephyr/drivers/i2c.h>
 #include <zephyr/drivers/pinctrl.h>
+#include <zephyr/drivers/counter.h>
 #include <soc.h>
 
 /* Logging includes */
@@ -76,6 +77,7 @@ struct i2c_mspm0g3xxx_config {
 	const struct pinctrl_dev_config *pinctrl;
 	void (*interrupt_init_function)(const struct device *dev);
 	uint32_t dt_bitrate;
+	const struct device *watchdog_timer;
 };
 
 struct i2c_mspm0g3xxx_data {
@@ -92,6 +94,7 @@ struct i2c_mspm0g3xxx_data {
 	int target_rx_valid;
 	struct k_sem i2c_busy_sem;
 	struct k_sem transfer_timeout_sem;
+	struct counter_alarm_cfg watchdog_timer_cfg;
 };
 
 #ifdef CONFIG_I2C_MSPM0G3XXX_TARGET_SUPPORT
@@ -111,6 +114,58 @@ static K_KERNEL_STACK_DEFINE(i2c_mspm0g3xxx_target_stack,
 			     CONFIG_I2C_MSPM0G3XXX_TARGET_THREAD_STACK_SIZE);
 static struct k_thread i2c_mspm0g3xxx_target_thread;
 
+static void i2c_mspm0g3xxx_target_stop_watchdog(struct i2c_mspm0g3xxx_data *data) {
+	const struct i2c_mspm0g3xxx_config *config = data->cfg;
+
+	if (!config->watchdog_timer) {
+		return;
+	}
+
+	int err = counter_stop(config-> watchdog_timer);
+	if (err != 0) {
+		LOG_ERR("Failed to stop the timer, err: %d", err);
+	}
+
+	err = counter_cancel_channel_alarm(config->watchdog_timer, 0);
+	if (err != 0) {
+		LOG_ERR("Failed to cancel the timer alarm, err: %d", err);
+	}
+}
+
+static void i2c_mspm0g3xxx_target_reset(const struct device *dev, uint8_t channel, uint32_t ticks,
+                             void *user_data)
+{
+       struct i2c_mspm0g3xxx_data *data = user_data;
+       const struct i2c_mspm0g3xxx_config *config = data->cfg;
+
+       DL_I2C_setTargetACKOverrideValue((I2C_Regs *)config->base,
+                                        DL_I2C_TARGET_RESPONSE_OVERRIDE_VALUE_NACK);
+       DL_I2C_disableTargetClockStretching((I2C_Regs *)config->base);
+       DL_I2C_disablePower((I2C_Regs *)config->base);
+       z_except_reason(CONFIG_I2C_MSPM0G3XXX_WATCHDOG_PANIC_CODE);
+}
+
+static void i2c_mspm0g3xxx_target_start_watchdog(struct i2c_mspm0g3xxx_data *data)
+{
+	const struct i2c_mspm0g3xxx_config *config = data->cfg;
+	struct counter_alarm_cfg *watchdog_timer_cfg = &data->watchdog_timer_cfg;
+
+	if (!config->watchdog_timer)
+		return;
+
+	i2c_mspm0g3xxx_target_stop_watchdog(data);
+
+	int err = counter_set_channel_alarm(config->watchdog_timer, 0, watchdog_timer_cfg);
+	if (err != 0) {
+		LOG_ERR("Failed to cancel the timer alarm, err: %d", err);
+	}
+
+	err = counter_start(config->watchdog_timer);
+	if (err != 0) {
+		LOG_ERR("Failed to start the timer, err: %d", err);
+	}
+}
+
 void i2c_mspm0g3xxx_target_thread_work(void)
 {
 	struct i2c_mspm0g3xxx_target_msg target_msg;
@@ -142,8 +197,10 @@ void i2c_mspm0g3xxx_target_thread_work(void)
 			if (data->state == I2C_mspm0g3xxx_TARGET_STARTED) {
 				data->state = I2C_mspm0g3xxx_TARGET_RX_INPROGRESS;
 				if (tconfig->callbacks->write_requested != NULL) {
+					i2c_mspm0g3xxx_target_start_watchdog(data);
 					data->target_rx_valid =
 						tconfig->callbacks->write_requested(tconfig);
+					i2c_mspm0g3xxx_target_stop_watchdog(data);
 				}
 			}
 			/* Store received data in buffer */
@@ -154,9 +211,11 @@ void i2c_mspm0g3xxx_target_thread_work(void)
 					if (data->target_rx_valid == 0) {
 						nextByte = DL_I2C_receiveTargetData(
 							(I2C_Regs *)config->base);
+						i2c_mspm0g3xxx_target_start_watchdog(data);
 						data->target_rx_valid =
 							tconfig->callbacks->write_received(
 								tconfig, nextByte);
+						i2c_mspm0g3xxx_target_stop_watchdog(data);
 
 						if (data->target_rx_valid == 0) {
 							DL_I2C_setTargetACKOverrideValue(
@@ -183,8 +242,10 @@ void i2c_mspm0g3xxx_target_thread_work(void)
 			/* Fill TX FIFO if there are more bytes to send */
 			if (tconfig->callbacks->read_requested != NULL) {
 				uint8_t nextByte;
+				i2c_mspm0g3xxx_target_start_watchdog(data);
 				data->target_tx_valid =
 					tconfig->callbacks->read_requested(tconfig, &nextByte);
+				i2c_mspm0g3xxx_target_stop_watchdog(data);
 				if (data->target_tx_valid == 0) {
 					DL_I2C_transmitTargetData((I2C_Regs *)config->base,
 								  nextByte);
@@ -203,8 +264,10 @@ void i2c_mspm0g3xxx_target_thread_work(void)
 				 * will be filled in */
 				uint8_t nextByte;
 				if (data->target_tx_valid == 0) {
+					i2c_mspm0g3xxx_target_start_watchdog(data);
 					data->target_tx_valid = tconfig->callbacks->read_processed(
 						tconfig, &nextByte);
+					i2c_mspm0g3xxx_target_stop_watchdog(data);
 				}
 
 				if (data->target_tx_valid == 0) {
@@ -221,7 +284,9 @@ void i2c_mspm0g3xxx_target_thread_work(void)
 			data->state = I2C_mspm0g3xxx_IDLE;
 			k_sem_give(&data->i2c_busy_sem);
 			if (tconfig->callbacks->stop) {
+				i2c_mspm0g3xxx_target_start_watchdog(data);
 				tconfig->callbacks->stop(tconfig);
+				i2c_mspm0g3xxx_target_stop_watchdog(data);
 			}
 			break;
 		default:
@@ -768,12 +833,25 @@ static int i2c_mspm0g3xxx_init(const struct device *dev)
 			config->clock_frequency);
 		return -EINVAL;
 	}
+
 	LOG_DBG("DT bitrate %uHz (%u)", config->clock_frequency,
 		config->dt_bitrate);
 
 	k_sem_init(&data->i2c_busy_sem, 0, 1);
 	k_sem_init(&data->transfer_timeout_sem, 1, 1);
 
+	if (config->watchdog_timer) {
+		if (!device_is_ready(config->watchdog_timer)) {
+			LOG_ERR("Watchdog timer is not ready");
+			return -EINVAL;
+		}
+
+		data->watchdog_timer_cfg.user_data = (void *)data;
+		data->watchdog_timer_cfg.callback = i2c_mspm0g3xxx_target_reset;
+		data->watchdog_timer_cfg.ticks = counter_us_to_ticks(
+			config->watchdog_timer, CONFIG_I2C_MSPM0G3XXX_WATCHDOG_TIMEOUT);
+	}
+
 	/* Init power */
 	DL_I2C_reset((I2C_Regs *)config->base);
 	DL_I2C_enablePower((I2C_Regs *)config->base);
@@ -895,6 +973,7 @@ static const struct i2c_driver_api i2c_mspm0g3xxx_driver_api = {
 				    .divideRatio = DL_I2C_CLOCK_DIVIDE_1},                         \
 		.dt_bitrate = CALC_DT_BITRATE(DT_INST_PROP(index, clock_frequency),		   \
 			DT_INST_PROP_BY_PHANDLE(index, clocks, clock_frequency)),		   \
+		.watchdog_timer = DEVICE_DT_GET_OR_NULL(DT_PHANDLE(DT_DRV_INST(index), watchdog_timer)),\
 	};											   \
                                                                                                    \
 	static struct i2c_mspm0g3xxx_data i2c_mspm0g3xxx_data_##index = {                          \
@@ -903,7 +982,7 @@ static const struct i2c_driver_api i2c_mspm0g3xxx_driver_api = {
                                                                                                    \
 	I2C_DEVICE_DT_INST_DEFINE(index, i2c_mspm0g3xxx_init, NULL, &i2c_mspm0g3xxx_data_##index,  \
 				  &i2c_mspm0g3xxx_cfg_##index, POST_KERNEL,                        \
-				  CONFIG_I2C_INIT_PRIORITY, &i2c_mspm0g3xxx_driver_api);           \
+				  CONFIG_COUNTER_INIT_PRIORITY, &i2c_mspm0g3xxx_driver_api);           \
                                                                                                    \
 	INTERRUPT_INIT_FUNCTION(index)