spi: rspi: Use core SPI_MASTER_MUST_[RT]X handling

RSPI needs dummy transfers to generate the SPI clock on receive.
RSPI-RZ and QSPI always do both transmit and receive.

Use the SPI core SPI_MASTER_MUST_RX/SPI_MASTER_MUST_TX infrastructure
instead of checking for the presence of buffers and providing dummy data
ourselves (for PIO), or providing a dummy buffer (for DMA).

rspi_receive_dma() now provides full duplex DMA transfers on RSPI, and is
renamed to rspi_send_receive_dma().

As the SPI core will always provide a TX buffer, the logic to choose
between DMA send and DMA send/receive in rspi_transfer_one() now has to
check for the presence of an RX buffer. Likewise for the DMA availability
tests in rspi_is_dma().

The buffer tests in qspi_transfer_one() are now always true, so they're
removed.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

1 files changed, 58 insertions, 74 deletions

diff --git a/drivers/spi/spi-rspi.c b/drivers/spi/spi-rspi.c
index 3bd06fd9af47..ece8f6037943 100644
--- a/drivers/spi/spi-rspi.c
+++ b/drivers/spi/spi-rspi.c
@@ -183,8 +183,6 @@
 #define SPBFCR_TXTRG_MASK       0x30    /* Transmit Buffer Data Triggering Number */
 #define SPBFCR_RXTRG_MASK       0x07    /* Receive Buffer Data Triggering Number */
 
-#define DUMMY_DATA              0x00
-
 struct rspi_data {
         void __iomem *addr;
         u32 max_speed_hz;
@@ -252,6 +250,7 @@ struct spi_ops {
         int (*transfer_one)(struct spi_master *master, struct spi_device *spi,
                             struct spi_transfer *xfer);
         u16 mode_bits;
+        u16 flags;
 };
 
 /*
@@ -552,42 +551,38 @@ static void qspi_receive_init(const struct rspi_data *rspi)
         rspi_write8(rspi, 0, QSPI_SPBFCR);
 }
 
-static int rspi_receive_dma(struct rspi_data *rspi, struct spi_transfer *t)
+static int rspi_send_receive_dma(struct rspi_data *rspi, struct spi_transfer *t)
 {
-        struct scatterlist sg, sg_dummy;
-        void *dummy = NULL, *rx_buf = t->rx_buf;
-        struct dma_async_tx_descriptor *desc, *desc_dummy;
+        struct scatterlist sg_rx, sg_tx;
+        const void *tx_buf = t->tx_buf;
+        void *rx_buf = t->rx_buf;
+        struct dma_async_tx_descriptor *desc_tx, *desc_rx;
         unsigned int len = t->len;
         int ret = 0;
 
-        /* prepare dummy transfer to generate SPI clocks */
-        dummy = kzalloc(len, GFP_KERNEL);
-        if (!dummy) {
-                ret = -ENOMEM;
-                goto end_nomap;
-        }
-        if (!rspi_dma_map_sg(&sg_dummy, dummy, len, rspi->chan_tx,
-                             DMA_TO_DEVICE)) {
-                ret = -EFAULT;
-                goto end_nomap;
-        }
-        desc_dummy = dmaengine_prep_slave_sg(rspi->chan_tx, &sg_dummy, 1,
+        /* prepare transmit transfer */
+        if (!rspi_dma_map_sg(&sg_tx, tx_buf, len, rspi->chan_tx,
+                             DMA_TO_DEVICE))
+                return -EFAULT;
+
+        desc_tx = dmaengine_prep_slave_sg(rspi->chan_tx, &sg_tx, 1,
                         DMA_TO_DEVICE, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
-        if (!desc_dummy) {
+        if (!desc_tx) {
                 ret = -EIO;
-                goto end_dummy_mapped;
+                goto end_tx_mapped;
         }
 
         /* prepare receive transfer */
-        if (!rspi_dma_map_sg(&sg, rx_buf, len, rspi->chan_rx,
+        if (!rspi_dma_map_sg(&sg_rx, rx_buf, len, rspi->chan_rx,
                              DMA_FROM_DEVICE)) {
                 ret = -EFAULT;
-                goto end_dummy_mapped;
+                goto end_tx_mapped;
 
         }
-        desc = dmaengine_prep_slave_sg(rspi->chan_rx, &sg, 1, DMA_FROM_DEVICE,
-                                       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
-        if (!desc) {
+        desc_rx = dmaengine_prep_slave_sg(rspi->chan_rx, &sg_rx, 1,
+                                          DMA_FROM_DEVICE,
+                                          DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+        if (!desc_rx) {
                 ret = -EIO;
                 goto end;
         }
@@ -606,13 +601,13 @@ static int rspi_receive_dma(struct rspi_data *rspi, struct spi_transfer *t)
         rspi_enable_irq(rspi, SPCR_SPTIE | SPCR_SPRIE);
         rspi->dma_callbacked = 0;
 
-        desc->callback = rspi_dma_complete;
-        desc->callback_param = rspi;
-        dmaengine_submit(desc);
+        desc_rx->callback = rspi_dma_complete;
+        desc_rx->callback_param = rspi;
+        dmaengine_submit(desc_rx);
         dma_async_issue_pending(rspi->chan_rx);
 
-        desc_dummy->callback = NULL;    /* No callback */
-        dmaengine_submit(desc_dummy);
+        desc_tx->callback = NULL;       /* No callback */
+        dmaengine_submit(desc_tx);
         dma_async_issue_pending(rspi->chan_tx);
 
         ret = wait_event_interruptible_timeout(rspi->wait,
@@ -628,21 +623,19 @@ static int rspi_receive_dma(struct rspi_data *rspi, struct spi_transfer *t)
                 enable_irq(rspi->rx_irq);
 
 end:
-        rspi_dma_unmap_sg(&sg, rspi->chan_rx, DMA_FROM_DEVICE);
-end_dummy_mapped:
-        rspi_dma_unmap_sg(&sg_dummy, rspi->chan_tx, DMA_TO_DEVICE);
-end_nomap:
-        kfree(dummy);
-
+        rspi_dma_unmap_sg(&sg_rx, rspi->chan_rx, DMA_FROM_DEVICE);
+end_tx_mapped:
+        rspi_dma_unmap_sg(&sg_tx, rspi->chan_tx, DMA_TO_DEVICE);
         return ret;
 }
 
 static int rspi_is_dma(const struct rspi_data *rspi, struct spi_transfer *t)
 {
-        if (t->tx_buf && rspi->chan_tx)
-                return 1;
         /* If the module receives data by DMAC, it also needs TX DMAC */
-        if (t->rx_buf && rspi->chan_tx && rspi->chan_rx)
+        if (t->rx_buf)
+                return rspi->chan_tx && rspi->chan_rx;
+
+        if (rspi->chan_tx)
                 return 1;
 
         return 0;
@@ -654,7 +647,7 @@ static int rspi_transfer_out_in(struct rspi_data *rspi,
         int remain = xfer->len, ret;
         const u8 *tx_buf = xfer->tx_buf;
         u8 *rx_buf = xfer->rx_buf;
-        u8 spcr, data;
+        u8 spcr;
 
         spcr = rspi_read8(rspi, RSPI_SPCR);
         if (rx_buf) {
@@ -666,8 +659,7 @@ static int rspi_transfer_out_in(struct rspi_data *rspi,
         rspi_write8(rspi, spcr, RSPI_SPCR);
 
         while (remain > 0) {
-                data = tx_buf ? *tx_buf++ : DUMMY_DATA;
-                ret = rspi_data_out(rspi, data);
+                ret = rspi_data_out(rspi, *tx_buf++);
                 if (ret < 0)
                         return ret;
                 if (rx_buf) {
@@ -689,20 +681,14 @@ static int rspi_transfer_one(struct spi_master *master, struct spi_device *spi,
                              struct spi_transfer *xfer)
 {
         struct rspi_data *rspi = spi_master_get_devdata(master);
-        int ret;
 
         if (!rspi_is_dma(rspi, xfer))
                 return rspi_transfer_out_in(rspi, xfer);
 
-        if (xfer->tx_buf) {
-                ret = rspi_send_dma(rspi, xfer);
-                if (ret < 0)
-                        return ret;
-        }
         if (xfer->rx_buf)
-                return rspi_receive_dma(rspi, xfer);
-
-        return 0;
+                return rspi_send_receive_dma(rspi, xfer);
+        else
+                return rspi_send_dma(rspi, xfer);
 }
 
 static int rspi_rz_transfer_out_in(struct rspi_data *rspi,
@@ -711,17 +697,14 @@ static int rspi_rz_transfer_out_in(struct rspi_data *rspi,
         int remain = xfer->len, ret;
         const u8 *tx_buf = xfer->tx_buf;
         u8 *rx_buf = xfer->rx_buf;
-        u8 data;
 
         rspi_rz_receive_init(rspi);
 
         while (remain > 0) {
-                data = tx_buf ? *tx_buf++ : DUMMY_DATA;
-                ret = rspi_data_out_in(rspi, data);
+                ret = rspi_data_out_in(rspi, *tx_buf++);
                 if (ret < 0)
                         return ret;
-                if (rx_buf)
-                        *rx_buf++ = ret;
+                *rx_buf++ = ret;
                 remain--;
         }
 
@@ -746,17 +729,14 @@ static int qspi_transfer_out_in(struct rspi_data *rspi,
         int remain = xfer->len, ret;
         const u8 *tx_buf = xfer->tx_buf;
         u8 *rx_buf = xfer->rx_buf;
-        u8 data;
 
         qspi_receive_init(rspi);
 
         while (remain > 0) {
-                data = tx_buf ? *tx_buf++ : DUMMY_DATA;
-                ret = rspi_data_out_in(rspi, data);
+                ret = rspi_data_out_in(rspi, *tx_buf++);
                 if (ret < 0)
                         return ret;
-                if (rx_buf)
-                        *rx_buf++ = ret;
+                *rx_buf++ = ret;
                 remain--;
         }
 
@@ -807,10 +787,10 @@ static int qspi_transfer_one(struct spi_master *master, struct spi_device *spi,
 
         if (spi->mode & SPI_LOOP) {
                 return qspi_transfer_out_in(rspi, xfer);
-        } else if (xfer->tx_buf && xfer->tx_nbits > SPI_NBITS_SINGLE) {
+        } else if (xfer->tx_nbits > SPI_NBITS_SINGLE) {
                 /* Quad or Dual SPI Write */
                 return qspi_transfer_out(rspi, xfer);
-        } else if (xfer->rx_buf && xfer->rx_nbits > SPI_NBITS_SINGLE) {
+        } else if (xfer->rx_nbits > SPI_NBITS_SINGLE) {
                 /* Quad or Dual SPI Read */
                 return qspi_transfer_in(rspi, xfer);
         } else {
@@ -1061,23 +1041,26 @@ static int rspi_remove(struct platform_device *pdev)
 }
 
 static const struct spi_ops rspi_ops = {
-        .set_config_register =          rspi_set_config_register,
-        .transfer_one =                 rspi_transfer_one,
-        .mode_bits =                    SPI_CPHA | SPI_CPOL | SPI_LOOP,
+        .set_config_register =  rspi_set_config_register,
+        .transfer_one =         rspi_transfer_one,
+        .mode_bits =            SPI_CPHA | SPI_CPOL | SPI_LOOP,
+        .flags =                SPI_MASTER_MUST_TX,
 };
 
 static const struct spi_ops rspi_rz_ops = {
-        .set_config_register =          rspi_rz_set_config_register,
-        .transfer_one =                 rspi_rz_transfer_one,
-        .mode_bits =                    SPI_CPHA | SPI_CPOL | SPI_LOOP,
+        .set_config_register =  rspi_rz_set_config_register,
+        .transfer_one =         rspi_rz_transfer_one,
+        .mode_bits =            SPI_CPHA | SPI_CPOL | SPI_LOOP,
+        .flags =                SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX,
 };
 
 static const struct spi_ops qspi_ops = {
-        .set_config_register =          qspi_set_config_register,
-        .transfer_one =                 qspi_transfer_one,
-        .mode_bits =                    SPI_CPHA | SPI_CPOL | SPI_LOOP |
-                                        SPI_TX_DUAL | SPI_TX_QUAD |
-                                        SPI_RX_DUAL | SPI_RX_QUAD,
+        .set_config_register =  qspi_set_config_register,
+        .transfer_one =         qspi_transfer_one,
+        .mode_bits =            SPI_CPHA | SPI_CPOL | SPI_LOOP |
+                                SPI_TX_DUAL | SPI_TX_QUAD |
+                                SPI_RX_DUAL | SPI_RX_QUAD,
+        .flags =                SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX,
 };
 
 #ifdef CONFIG_OF
@@ -1197,6 +1180,7 @@ static int rspi_probe(struct platform_device *pdev)
         master->prepare_message = rspi_prepare_message;
         master->unprepare_message = rspi_unprepare_message;
         master->mode_bits = ops->mode_bits;
+        master->flags = ops->flags;
         master->dev.of_node = pdev->dev.of_node;
 
         ret = platform_get_irq_byname(pdev, "rx");