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drivers: spi_context: Fix handling of zero-length buffers

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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>
This commit is contained in:
Andrzej Głąbek 2021-10-29 10:49:53 +02:00 • committed by Carles Cufí
commit 688d81813e
1 changed files with 43 additions and 38 deletions
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81
drivers/spi/spi_context.h
View file

@ -272,6 +272,25 @@ static inline void spi_context_unlock_unconditionally(struct spi_context *ctx)
}
}
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,
@ -280,29 +299,17 @@ void spi_context_buffers_setup(struct spi_context *ctx,
{
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;
@ -331,14 +338,13 @@ void spi_context_update_tx(struct spi_context *ctx, uint8_t dfs, uint32_t len)
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;
}
@ -379,14 +385,13 @@ void spi_context_update_rx(struct spi_context *ctx, uint8_t dfs, uint32_t len)
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;
}