drivers: spi_context: Fix spi_context_xx_len_left

These two functions were using the value of ctx->xx_len wrong, the unit
is in words, not bytes, but spi_context_count_xx_buf_lens was iterating
over the length of bytes, not words.

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

Author: decsny

drivers/spi/spi_context.h

@@ -661,17 +661,17 @@ static inline size_t spi_context_total_rx_len(struct spi_context *ctx)
 /* Similar to spi_context_total_tx_len, except does not count words that have been finished
  * in the current buffer, ie only including what is remaining in the current buffer in the sum.
  */
-static inline size_t spi_context_tx_len_left(struct spi_context *ctx)
+static inline size_t spi_context_tx_len_left(struct spi_context *ctx, uint8_t dfs)
 {
-	return ctx->tx_len + spi_context_count_tx_buf_lens(ctx, 1);
+	return (ctx->tx_len * dfs) + spi_context_count_tx_buf_lens(ctx, 1);
 }
 
 /* Similar to spi_context_total_rx_len, except does not count words that have been finished
  * in the current buffer, ie only including what is remaining in the current buffer in the sum.
  */
-static inline size_t spi_context_rx_len_left(struct spi_context *ctx)
+static inline size_t spi_context_rx_len_left(struct spi_context *ctx, uint8_t dfs)
 {
-	return ctx->rx_len + spi_context_count_rx_buf_lens(ctx, 1);
+	return (ctx->rx_len * dfs) + spi_context_count_rx_buf_lens(ctx, 1);
 }
 
 #ifdef __cplusplus

drivers/spi/spi_nxp_lpspi/spi_nxp_lpspi.c

@@ -241,6 +241,7 @@ static void lpspi_isr(const struct device *dev)
 	const struct lpspi_config *config = dev->config;
 	struct lpspi_data *data = dev->data;
 	struct lpspi_driver_data *lpspi_data = (struct lpspi_driver_data *)data->driver_data;
+	uint8_t word_size_bytes = lpspi_data->word_size_bytes;
 	struct spi_context *ctx = &data->ctx;
 	uint32_t status_flags = base->SR;
 
@@ -252,7 +253,7 @@ static void lpspi_isr(const struct device *dev)
 		lpspi_handle_tx_irq(dev);
 	}
 
-	if (spi_context_rx_len_left(ctx) == 0) {
+	if (spi_context_rx_len_left(ctx, word_size_bytes) == 0) {
 		base->IER &= ~LPSPI_IER_RDIE_MASK;
 		base->CR |= LPSPI_CR_RRF_MASK; /* flush rx fifo */
 	}
@@ -274,7 +275,8 @@ static void lpspi_isr(const struct device *dev)
 		lpspi_data->fill_len = fill_len;
 	}
 
-	if (spi_context_rx_len_left(ctx) == 1 && (LPSPI_VERID_MAJOR(base->VERID) < 2)) {
+	if ((DIV_ROUND_UP(spi_context_rx_len_left(ctx, word_size_bytes), word_size_bytes) == 1) &&
+	    (LPSPI_VERID_MAJOR(base->VERID) < 2)) {
 		/* Due to stalling behavior on older LPSPI,
 		 * need to end xfer in order to get last bit clocked out on bus.
 		 */