summaryrefslogtreecommitdiffstats
path: root/drivers/spi/spi-fsl-espi.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/spi/spi-fsl-espi.c')
-rw-r--r--drivers/spi/spi-fsl-espi.c51
1 files changed, 47 insertions, 4 deletions
diff --git a/drivers/spi/spi-fsl-espi.c b/drivers/spi/spi-fsl-espi.c
index edb524f831a3..9ccbfbc75933 100644
--- a/drivers/spi/spi-fsl-espi.c
+++ b/drivers/spi/spi-fsl-espi.c
@@ -150,7 +150,8 @@ static void fsl_espi_copy_to_buf(struct spi_message *m,
list_for_each_entry(t, &m->transfers, transfer_list) {
if (t->tx_buf)
fsl_espi_memcpy_swab(buf, t->tx_buf, m, t);
- else
+ /* In RXSKIP mode controller shifts out zeros internally */
+ else if (!mspi->rxskip)
memset(buf, 0, t->len);
buf += t->len;
}
@@ -203,6 +204,37 @@ static int fsl_espi_check_message(struct spi_message *m)
return 0;
}
+static unsigned int fsl_espi_check_rxskip_mode(struct spi_message *m)
+{
+ struct spi_transfer *t;
+ unsigned int i = 0, rxskip = 0;
+
+ /*
+ * prerequisites for ESPI rxskip mode:
+ * - message has two transfers
+ * - first transfer is a write and second is a read
+ *
+ * In addition the current low-level transfer mechanism requires
+ * that the rxskip bytes fit into the TX FIFO. Else the transfer
+ * would hang because after the first FSL_ESPI_FIFO_SIZE bytes
+ * the TX FIFO isn't re-filled.
+ */
+ list_for_each_entry(t, &m->transfers, transfer_list) {
+ if (i == 0) {
+ if (!t->tx_buf || t->rx_buf ||
+ t->len > FSL_ESPI_FIFO_SIZE)
+ return 0;
+ rxskip = t->len;
+ } else if (i == 1) {
+ if (t->tx_buf || !t->rx_buf)
+ return 0;
+ }
+ i++;
+ }
+
+ return i == 2 ? rxskip : 0;
+}
+
static void fsl_espi_fill_tx_fifo(struct mpc8xxx_spi *mspi, u32 events)
{
u32 tx_fifo_avail;
@@ -281,7 +313,7 @@ static void fsl_espi_setup_transfer(struct spi_device *spi,
static int fsl_espi_bufs(struct spi_device *spi, struct spi_transfer *t)
{
struct mpc8xxx_spi *mpc8xxx_spi = spi_master_get_devdata(spi->master);
- u32 mask;
+ u32 mask, spcom;
int ret;
mpc8xxx_spi->rx_len = t->len;
@@ -293,8 +325,18 @@ static int fsl_espi_bufs(struct spi_device *spi, struct spi_transfer *t)
reinit_completion(&mpc8xxx_spi->done);
/* Set SPCOM[CS] and SPCOM[TRANLEN] field */
- fsl_espi_write_reg(mpc8xxx_spi, ESPI_SPCOM,
- (SPCOM_CS(spi->chip_select) | SPCOM_TRANLEN(t->len - 1)));
+ spcom = SPCOM_CS(spi->chip_select);
+ spcom |= SPCOM_TRANLEN(t->len - 1);
+
+ /* configure RXSKIP mode */
+ if (mpc8xxx_spi->rxskip) {
+ spcom |= SPCOM_RXSKIP(mpc8xxx_spi->rxskip);
+ mpc8xxx_spi->tx_len = mpc8xxx_spi->rxskip;
+ mpc8xxx_spi->rx_len = t->len - mpc8xxx_spi->rxskip;
+ mpc8xxx_spi->rx = t->rx_buf + mpc8xxx_spi->rxskip;
+ }
+
+ fsl_espi_write_reg(mpc8xxx_spi, ESPI_SPCOM, spcom);
/* enable interrupts */
mask = SPIM_DON;
@@ -326,6 +368,7 @@ static int fsl_espi_trans(struct spi_message *m, struct spi_transfer *trans)
struct spi_device *spi = m->spi;
int ret;
+ mspi->rxskip = fsl_espi_check_rxskip_mode(m);
fsl_espi_copy_to_buf(m, mspi);
fsl_espi_setup_transfer(spi, trans);