spi_nxp_lpspi: Simplify tx ctx update

There is no need to update the tx context in interrupt instead of
directly after the fill, this just makes the code more complex. Also,
the spi context header already handled iterating over buffers so we can
remove that code too.

Signed-off-by: Declan Snyder <declan.snyder@nxp.com>

Author: decsny

drivers/spi/spi_nxp_lpspi/spi_nxp_lpspi.c

@@ -12,7 +12,6 @@ LOG_MODULE_DECLARE(spi_lpspi, CONFIG_SPI_LOG_LEVEL);
 #include "spi_nxp_lpspi_priv.h"
 
 struct lpspi_driver_data {
-	size_t fill_len;
 	uint8_t word_size_bytes;
 };
 
@@ -126,7 +125,7 @@ static inline void lpspi_fill_tx_fifo(const struct device *dev, const uint8_t *b
 		buf_remaining_bytes -= word_size;
 	}
 
-	LOG_DBG("Filled TX FIFO to %d words (%d bytes)", lpspi_data->fill_len, offset);
+	LOG_DBG("Filled TX FIFO to %d words (%d bytes)", fill_len, offset);
 }
 
 /* just fills TX fifo with the specified amount of NOPS */
@@ -187,34 +186,26 @@ static void lpspi_next_tx_fill(const struct device *dev)
 		actual_filled += next_buf_fill;
 	}
 
-	lpspi_data->fill_len = actual_filled;
+	spi_context_update_tx(ctx, lpspi_data->word_size_bytes, actual_filled);
 }
 
 static inline void lpspi_handle_tx_irq(const struct device *dev)
 {
 	LPSPI_Type *base = (LPSPI_Type *)DEVICE_MMIO_NAMED_GET(dev, reg_base);
 	struct lpspi_data *data = dev->data;
-	struct lpspi_driver_data *lpspi_data = (struct lpspi_driver_data *)data->driver_data;
 	struct spi_context *ctx = &data->ctx;
 
 	base->SR = LPSPI_SR_TDF_MASK;
 
 	/* If we receive a TX interrupt but no more data is available,
-	 * we can be sure that all data has been written to the bus.
+	 * we can be sure that all data has been written to the fifo.
 	 * Disable the interrupt to signal that we are done.
 	 */
 	if (!spi_context_tx_on(ctx)) {
 		base->IER &= ~LPSPI_IER_TDIE_MASK;
 		return;
 	}
 
-	while (spi_context_tx_on(ctx) && lpspi_data->fill_len > 0) {
-		size_t this_buf_words_sent = MIN(lpspi_data->fill_len, ctx->tx_len);
-
-		spi_context_update_tx(ctx, lpspi_data->word_size_bytes, this_buf_words_sent);
-		lpspi_data->fill_len -= this_buf_words_sent;
-	}
-
 	lpspi_next_tx_fill(dev);
 }
 
@@ -272,7 +263,6 @@ static void lpspi_isr(const struct device *dev)
 					max_fill - tx_current_fifo_len : 0;
 
 		lpspi_fill_tx_fifo_nop(dev, fill_len);
-		lpspi_data->fill_len = fill_len;
 	}
 
 	if ((DIV_ROUND_UP(spi_context_rx_len_left(ctx, word_size_bytes), word_size_bytes) == 1) &&