spi: spi-fsl-dspi: Fix per transfer cs_change handling

As of 92dc20d83adec565378254c0630e839ff5674e14, transfer->cs_change has
been supported for non-last transfers, but not for last transfer.

This change brings handling of cs_change in line with the specification in
spi.h, implementing handling of transfer->cs_change for all transfers.

The value for CMD FIFO is precalculated with transfer->cs_change field
taken into account, allowing for CS de-activate between transfers and
keeping CS activated after last transfer.

Signed-off-by: Esben Haabendal <eha@deif.com>
Acked-by: Martin Hundebøll <martin@geanix.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index 3bf135bf8b931141ceb3caa40a5c7cf31c738405..c0c3b8bf278142cce8afc6e4ca7466cda42ca504 100644 (file)
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -84,11 +84,16 @@
 #define SPI_RSER_TCFQE         0x80000000
 
 #define SPI_PUSHR              0x34
-#define SPI_PUSHR_CONT         (1 << 31)
-#define SPI_PUSHR_CTAS(x)      (((x) & 0x00000003) << 28)
-#define SPI_PUSHR_EOQ          (1 << 27)
-#define SPI_PUSHR_CTCNT        (1 << 26)
-#define SPI_PUSHR_PCS(x)       (((1 << x) & 0x0000003f) << 16)
+#define SPI_PUSHR_CMD_CONT     (1 << 15)
+#define SPI_PUSHR_CONT         (SPI_PUSHR_CMD_CONT << 16)
+#define SPI_PUSHR_CMD_CTAS(x)  (((x) & 0x0003) << 12)
+#define SPI_PUSHR_CTAS(x)      (SPI_PUSHR_CMD_CTAS(x) << 16)
+#define SPI_PUSHR_CMD_EOQ      (1 << 11)
+#define SPI_PUSHR_EOQ          (SPI_PUSHR_CMD_EOQ << 16)
+#define SPI_PUSHR_CMD_CTCNT    (1 << 10)
+#define SPI_PUSHR_CTCNT                (SPI_PUSHR_CMD_CTCNT << 16)
+#define SPI_PUSHR_CMD_PCS(x)   ((1 << x) & 0x003f)
+#define SPI_PUSHR_PCS(x)       (SPI_PUSHR_CMD_PCS(x) << 16)
 #define SPI_PUSHR_TXDATA(x)    ((x) & 0x0000ffff)
 
 #define SPI_PUSHR_SLAVE        0x34
@@ -189,9 +194,8 @@ struct fsl_dspi {
        void                    *rx;
        void                    *rx_end;
        char                    dataflags;
-       u8                      cs;
        u16                     void_write_data;
-       u32                     cs_change;
+       u16                     tx_cmd;
        const struct fsl_dspi_devtype_data *devtype_data;
 
        wait_queue_head_t       waitq;
@@ -254,8 +258,6 @@ static int dspi_next_xfer_dma_submit(struct fsl_dspi *dspi)
 
        for (i = 0; i < dma->curr_xfer_len; i++) {
                dspi->dma->tx_dma_buf[i] = dspi_data_to_pushr(dspi, tx_word);
-               if ((dspi->cs_change) && (!dspi->len))
-                       dspi->dma->tx_dma_buf[i] &= ~SPI_PUSHR_CONT;
        }
 
        dma->tx_desc = dmaengine_prep_slave_single(dma->chan_tx,
@@ -534,21 +536,22 @@ static void ns_delay_scale(char *psc, char *sc, int delay_ns,
 
 static u32 dspi_data_to_pushr(struct fsl_dspi *dspi, int tx_word)
 {
-       u16 d16;
+       u16 data, cmd;
 
        if (dspi->tx) {
-               d16 = tx_word ? *(u16 *)dspi->tx : *(u8 *)dspi->tx;
+               data = tx_word ? *(u16 *)dspi->tx : *(u8 *)dspi->tx;
                dspi->tx += tx_word + 1;
        } else {
-               d16 = dspi->void_write_data;
+               data = dspi->void_write_data;
        }
 
        dspi->len -= tx_word + 1;
 
-       return  SPI_PUSHR_TXDATA(d16) |
-               SPI_PUSHR_PCS(dspi->cs) |
-               SPI_PUSHR_CTAS(0) |
-               SPI_PUSHR_CONT;
+       cmd = dspi->tx_cmd;
+       if (dspi->len > 0)
+               cmd |= SPI_PUSHR_CMD_CONT;
+
+       return (cmd << 16) | SPI_PUSHR_TXDATA(data);
 }
 
 static void dspi_data_from_popr(struct fsl_dspi *dspi, int rx_word)
@@ -587,12 +590,9 @@ static int dspi_eoq_write(struct fsl_dspi *dspi)
 
                dspi_pushr = dspi_data_to_pushr(dspi, tx_word);
 
-               if (dspi->len == 0 || tx_count == DSPI_FIFO_SIZE - 1) {
-                       /* last transfer in the transfer */
+               if (dspi->len == 0 || tx_count == DSPI_FIFO_SIZE - 1)
+                       /* request EOQ flag for last transfer in queue */
                        dspi_pushr |= SPI_PUSHR_EOQ;
-                       if ((dspi->cs_change) && (!dspi->len))
-                               dspi_pushr &= ~SPI_PUSHR_CONT;
-               }
 
                regmap_write(dspi->regmap, SPI_PUSHR, dspi_pushr);
 
@@ -635,9 +635,6 @@ static int dspi_tcfq_write(struct fsl_dspi *dspi)
 
        dspi_pushr = dspi_data_to_pushr(dspi, tx_word);
 
-       if ((dspi->cs_change) && (!dspi->len))
-               dspi_pushr &= ~SPI_PUSHR_CONT;
-
        regmap_write(dspi->regmap, SPI_PUSHR, dspi_pushr);
 
        return tx_word + 1;
@@ -672,11 +669,26 @@ static int dspi_transfer_one_message(struct spi_master *master,
                dspi->cur_transfer = transfer;
                dspi->cur_msg = message;
                dspi->cur_chip = spi_get_ctldata(spi);
-               dspi->cs = spi->chip_select;
-               dspi->cs_change = 0;
+               /* Prepare command word for CMD FIFO */
+               dspi->tx_cmd = SPI_PUSHR_CMD_CTAS(0) |
+                       SPI_PUSHR_CMD_PCS(spi->chip_select);
                if (list_is_last(&dspi->cur_transfer->transfer_list,
-                                &dspi->cur_msg->transfers) || transfer->cs_change)
-                       dspi->cs_change = 1;
+                                &dspi->cur_msg->transfers)) {
+                       /* Leave PCS activated after last transfer when
+                        * cs_change is set.
+                        */
+                       if (transfer->cs_change)
+                               dspi->tx_cmd |= SPI_PUSHR_CMD_CONT;
+               } else {
+                       /* Keep PCS active between transfers in same message
+                        * when cs_change is not set, and de-activate PCS
+                        * between transfers in the same message when
+                        * cs_change is set.
+                        */
+                       if (!transfer->cs_change)
+                               dspi->tx_cmd |= SPI_PUSHR_CMD_CONT;
+               }
+
                dspi->void_write_data = dspi->cur_chip->void_write_data;
 
                dspi->dataflags = 0;