drivers: spi_context: Fix handling of zero-length buffers
In some cases, it is quite useful to have the possibility to also
include zero-length buffers in a buffer set used in transfers
(for example, when frames in a protocol consist of several parts,
of which some are optional). So far, the behavior of spi_context
update functions was that the transfer in a given direction was
finished when a zero-length buffer was encountered in the buffer
set. Change those functions to simply skip such buffers. Correct
in the same way also the spi_context_buffers_setup() function.
Signed-off-by: Andrzej Głąbek <andrzej.glabek@nordicsemi.no>
diff --git a/drivers/spi/spi_context.h b/drivers/spi/spi_context.h
index f5862f5..d1c181a 100644
--- a/drivers/spi/spi_context.h
+++ b/drivers/spi/spi_context.h
@@ -248,6 +248,25 @@
}
}
+static inline void *spi_context_get_next_buf(const struct spi_buf **current,
+ size_t *count,
+ size_t *buf_len,
+ uint8_t dfs)
+{
+ /* This loop skips zero-length buffers in the set, if any. */
+ while (*count) {
+ if (((*current)->len / dfs) != 0) {
+ *buf_len = (*current)->len / dfs;
+ return (*current)->buf;
+ }
+ ++(*current);
+ --(*count);
+ }
+
+ *buf_len = 0;
+ return NULL;
+}
+
static inline
void spi_context_buffers_setup(struct spi_context *ctx,
const struct spi_buf_set *tx_bufs,
@@ -256,29 +275,17 @@
{
LOG_DBG("tx_bufs %p - rx_bufs %p - %u", tx_bufs, rx_bufs, dfs);
- if (tx_bufs) {
- ctx->current_tx = tx_bufs->buffers;
- ctx->tx_count = tx_bufs->count;
- ctx->tx_buf = (const uint8_t *)ctx->current_tx->buf;
- ctx->tx_len = ctx->current_tx->len / dfs;
- } else {
- ctx->current_tx = NULL;
- ctx->tx_count = 0;
- ctx->tx_buf = NULL;
- ctx->tx_len = 0;
- }
+ ctx->current_tx = tx_bufs ? tx_bufs->buffers : NULL;
+ ctx->tx_count = ctx->current_tx ? tx_bufs->count : 0;
+ ctx->tx_buf = (const uint8_t *)
+ spi_context_get_next_buf(&ctx->current_tx, &ctx->tx_count,
+ &ctx->tx_len, dfs);
- if (rx_bufs) {
- ctx->current_rx = rx_bufs->buffers;
- ctx->rx_count = rx_bufs->count;
- ctx->rx_buf = (uint8_t *)ctx->current_rx->buf;
- ctx->rx_len = ctx->current_rx->len / dfs;
- } else {
- ctx->current_rx = NULL;
- ctx->rx_count = 0;
- ctx->rx_buf = NULL;
- ctx->rx_len = 0;
- }
+ ctx->current_rx = rx_bufs ? rx_bufs->buffers : NULL;
+ ctx->rx_count = ctx->current_rx ? rx_bufs->count : 0;
+ ctx->rx_buf = (uint8_t *)
+ spi_context_get_next_buf(&ctx->current_rx, &ctx->rx_count,
+ &ctx->rx_len, dfs);
ctx->sync_status = 0;
@@ -307,14 +314,13 @@
ctx->tx_len -= len;
if (!ctx->tx_len) {
- ctx->tx_count--;
- if (ctx->tx_count) {
- ctx->current_tx++;
- ctx->tx_buf = (const uint8_t *)ctx->current_tx->buf;
- ctx->tx_len = ctx->current_tx->len / dfs;
- } else {
- ctx->tx_buf = NULL;
- }
+ /* Current buffer is done. Get the next one to be processed. */
+ ++ctx->current_tx;
+ --ctx->tx_count;
+ ctx->tx_buf = (const uint8_t *)
+ spi_context_get_next_buf(&ctx->current_tx,
+ &ctx->tx_count,
+ &ctx->tx_len, dfs);
} else if (ctx->tx_buf) {
ctx->tx_buf += dfs * len;
}
@@ -355,14 +361,13 @@
ctx->rx_len -= len;
if (!ctx->rx_len) {
- ctx->rx_count--;
- if (ctx->rx_count) {
- ctx->current_rx++;
- ctx->rx_buf = (uint8_t *)ctx->current_rx->buf;
- ctx->rx_len = ctx->current_rx->len / dfs;
- } else {
- ctx->rx_buf = NULL;
- }
+ /* Current buffer is done. Get the next one to be processed. */
+ ++ctx->current_rx;
+ --ctx->rx_count;
+ ctx->rx_buf = (uint8_t *)
+ spi_context_get_next_buf(&ctx->current_rx,
+ &ctx->rx_count,
+ &ctx->rx_len, dfs);
} else if (ctx->rx_buf) {
ctx->rx_buf += dfs * len;
}
