drivers: i2c: i2c_gecko: add exclusive access

- Add exclusive and atomic access to resource

Fixes #79110

Signed-off-by: Romain Pelletant <[email protected]>

Author: Romain Pelletant

drivers/i2c/i2c_gecko.c

@@ -37,6 +37,7 @@ struct i2c_gecko_config {
 
 struct i2c_gecko_data {
 	struct k_sem device_sync_sem;
+	struct k_sem bus_lock;
 	uint32_t dev_config;
 #if defined(CONFIG_I2C_TARGET)
 	struct i2c_target_config *target_cfg;
@@ -68,6 +69,8 @@ static int i2c_gecko_configure(const struct device *dev, uint32_t dev_config_raw
 		return -EINVAL;
 	}
 
+	k_sem_take(&data->bus_lock, K_FOREVER);
+
 	data->dev_config = dev_config_raw;
 	i2cInit.freq = baudrate;
 
@@ -77,6 +80,8 @@ static int i2c_gecko_configure(const struct device *dev, uint32_t dev_config_raw
 
 	I2C_Init(base, &i2cInit);
 
+	k_sem_give(&data->bus_lock);
+
 	return 0;
 }
 
@@ -93,6 +98,8 @@ static int i2c_gecko_transfer(const struct device *dev, struct i2c_msg *msgs, ui
 		return 0;
 	}
 
+	k_sem_take(&data->bus_lock, K_FOREVER);
+
 	seq.addr = addr << 1;
 
 	do {
@@ -137,6 +144,8 @@ static int i2c_gecko_transfer(const struct device *dev, struct i2c_msg *msgs, ui
 	} while (num_msgs);
 
 finish:
+	k_sem_give(&data->bus_lock);
+
 	if (ret != i2cTransferDone) {
 		ret = -EIO;
 	}
@@ -145,10 +154,16 @@ static int i2c_gecko_transfer(const struct device *dev, struct i2c_msg *msgs, ui
 
 static int i2c_gecko_init(const struct device *dev)
 {
+	struct i2c_gecko_data *data = dev->data;
 	const struct i2c_gecko_config *config = dev->config;
 	uint32_t bitrate_cfg;
 	int error;
 
+	/* Initialize mutex to guarantee that each transaction
+	 * is atomic and has exclusive access to the I2C bus
+	 */
+	k_sem_init(&data->bus_lock, 1, 1);
+
 	CMU_ClockEnable(config->clock, true);
 
 	error = pinctrl_apply_state(config->pcfg, PINCTRL_STATE_DEFAULT);