Commit a4ea1a1a authored by Jun Lin's avatar Jun Lin Committed by Benjamin Cabé
Browse files

drivers: i2c: npcx: enhance the transfer efficiency 



The i2c_transfer() API allows multiple msgs objects to be carried in a
transaction. After handling the current msgs object in the interrupt
context, the driver notifies the calling thread to buffer the next
msgs object and generate the Re-Start if required.
However, if the calling thread is preempted by higher priority threads,
the I2C transaction time may become non-deterministic (depending on the
execution time of higher-priority threads). This commits modifies the
driver to handle msgs objects entirely in the interrupt context to
improve the I2C transfer efficiency..

Signed-off-by: default avatarJun Lin <CHLin56@nuvoton.com>
parent 18277b48

drivers/i2c/i2c_npcx_controller.c

+51 −13
Original line number Diff line number Diff line
@@ -168,9 +168,12 @@ struct i2c_ctrl_data { 
	enum npcx_i2c_oper_state oper_state; /* controller operation state */

	int trans_err;  /* error code during transaction */

	struct i2c_msg *msg; /* cache msg for transaction state machine */

	struct i2c_msg *msg_head;

	int is_write; /* direction of current msg */

	uint8_t *ptr_msg; /* current msg pointer for FIFO read/write */

	uint16_t addr; /* slave address of transaction */

	uint8_t msg_max_num;

	uint8_t msg_curr_idx;

	uint8_t port; /* current port used the controller */

	bool is_configured; /* is port configured? */

	const struct npcx_i2c_timing_cfg *ptr_speed_confs;
@@ -639,6 +642,24 @@ static void i2c_ctrl_handle_write_int_event(const struct device *dev) 
			/* Wait for STOP completed */

			data->oper_state = NPCX_I2C_WAIT_STOP;

		} else {

			uint8_t next_msg_idx = data->msg_curr_idx + 1;



			if (next_msg_idx < data->msg_max_num) {

				struct i2c_msg *msg;



				data->msg_curr_idx = next_msg_idx;

				msg = data->msg_head + next_msg_idx;

				data->msg = msg;

				data->ptr_msg = msg->buf;

				if ((msg->flags & I2C_MSG_RW_MASK) == I2C_MSG_WRITE) {

					data->oper_state = NPCX_I2C_WRITE_FIFO;

				} else {

					data->is_write = 0;

					data->oper_state = NPCX_I2C_WAIT_RESTART;

					i2c_ctrl_start(dev);

				}

				return;

			}

			/* Disable interrupt and handle next message */

			i2c_ctrl_irq_enable(dev, 0);

		}
@@ -702,6 +723,27 @@ static void i2c_ctrl_handle_read_int_event(const struct device *dev) 
			/* Release bus */

			i2c_ctrl_hold_bus(dev, 0);

			return;

		} else if ((data->msg->flags & I2C_MSG_STOP) == 0) {

			uint8_t next_msg_idx = data->msg_curr_idx + 1;



			if (next_msg_idx < data->msg_max_num) {

				struct i2c_msg *msg;



				msg = data->msg_head + next_msg_idx;

				if ((msg->flags & I2C_MSG_RW_MASK) == I2C_MSG_READ) {



					data->msg_curr_idx = next_msg_idx;

					data->msg = msg;

					data->ptr_msg = msg->buf;



					/* Setup threshold of RX FIFO first */

					i2c_ctrl_fifo_rx_setup_threshold_nack(

						dev, msg->len, (msg->flags & I2C_MSG_STOP) != 0);

					/* Release bus */

					i2c_ctrl_hold_bus(dev, 0);

					return;

				}

			}

		}

	}
@@ -1258,7 +1300,7 @@ int npcx_i2c_ctrl_transfer(const struct device *i2c_dev, struct i2c_msg *msgs, 
{

	struct i2c_ctrl_data *const data = i2c_dev->data;

	int ret = 0;

	uint8_t i;

	struct i2c_msg *msg = msgs;



#ifdef CONFIG_I2C_TARGET

	/* I2c module has been configured to target mode */
@@ -1297,6 +1339,10 @@ int npcx_i2c_ctrl_transfer(const struct device *i2c_dev, struct i2c_msg *msgs, 
	data->trans_err = 0;

	data->addr = addr;



	data->msg_head = msgs;

	data->msg_max_num = num_msgs;

	data->msg_curr_idx = 0;



	/*

	 * Reset i2c event-completed semaphore before starting transactions.

	 * Some interrupt events such as BUS_ERROR might change its counter
@@ -1304,19 +1350,11 @@ int npcx_i2c_ctrl_transfer(const struct device *i2c_dev, struct i2c_msg *msgs, 
	 */

	k_sem_reset(&data->sync_sem);



	for (i = 0U; i < num_msgs; i++) {

		struct i2c_msg *msg = msgs + i;



		/* Handle write transaction */

	if ((msg->flags & I2C_MSG_RW_MASK) == I2C_MSG_WRITE) {

		ret = i2c_ctrl_proc_write_msg(i2c_dev, msg);

	} else { /* Handle read transaction */

		ret = i2c_ctrl_proc_read_msg(i2c_dev, msg);

	}

		if (ret < 0) {

			break;

		}

	}



	/* Check STOP completed? */

	if (data->oper_state == NPCX_I2C_WAIT_STOP) {

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