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

We need both RX and TX data for each transfer in any case (PIO, PDC, DMA).
So convert the driver to the core dummy buffer handling with the
SPI_MASTER_MUST_RX/SPI_MASTER_MUST_TX infrastructure.

This move changes the maximum PDC/DMA buffer handling to 65535 bytes
instead of a single page and sets master->max_dma_len to this value.

All dummy buffer management is removed from the driver.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 35 insertions, 96 deletions

diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index a9ae1836e1e2..8f20d4f75e4a 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -303,10 +303,6 @@ struct atmel_spi {
 
         struct completion       xfer_completion;
 
-        /* scratch buffer */
-        void                    *buffer;
-        dma_addr_t              buffer_dma;
-
         struct atmel_spi_caps   caps;
 
         bool                    use_dma;
@@ -327,7 +323,7 @@ struct atmel_spi_device {
         u32                     csr;
 };
 
-#define BUFFER_SIZE             PAGE_SIZE
+#define SPI_MAX_DMA_XFER        65535 /* true for both PDC and DMA */
 #define INVALID_DMA_ADDRESS     0xffffffff
 
 /*
@@ -612,14 +608,10 @@ static void atmel_spi_next_xfer_single(struct spi_master *master,
                 cpu_relax();
         }
 
-        if (xfer->tx_buf) {
-                if (xfer->bits_per_word > 8)
-                        spi_writel(as, TDR, *(u16 *)(xfer->tx_buf + xfer_pos));
-                else
-                        spi_writel(as, TDR, *(u8 *)(xfer->tx_buf + xfer_pos));
-        } else {
-                spi_writel(as, TDR, 0);
-        }
+        if (xfer->bits_per_word > 8)
+                spi_writel(as, TDR, *(u16 *)(xfer->tx_buf + xfer_pos));
+        else
+                spi_writel(as, TDR, *(u8 *)(xfer->tx_buf + xfer_pos));
 
         dev_dbg(master->dev.parent,
                 "  start pio xfer %p: len %u tx %p rx %p bitpw %d\n",
@@ -666,17 +658,12 @@ static void atmel_spi_next_xfer_fifo(struct spi_master *master,
 
         /* Fill TX FIFO */
         while (num_data >= 2) {
-                if (xfer->tx_buf) {
-                        if (xfer->bits_per_word > 8) {
-                                td0 = *words++;
-                                td1 = *words++;
-                        } else {
-                                td0 = *bytes++;
-                                td1 = *bytes++;
-                        }
+                if (xfer->bits_per_word > 8) {
+                        td0 = *words++;
+                        td1 = *words++;
                 } else {
-                        td0 = 0;
-                        td1 = 0;
+                        td0 = *bytes++;
+                        td1 = *bytes++;
                 }
 
                 spi_writel(as, TDR, (td1 << 16) | td0);
@@ -684,14 +671,10 @@ static void atmel_spi_next_xfer_fifo(struct spi_master *master,
         }
 
         if (num_data) {
-                if (xfer->tx_buf) {
-                        if (xfer->bits_per_word > 8)
-                                td0 = *words++;
-                        else
-                                td0 = *bytes++;
-                } else {
-                        td0 = 0;
-                }
+                if (xfer->bits_per_word > 8)
+                        td0 = *words++;
+                else
+                        td0 = *bytes++;
 
                 spi_writew(as, TDR, td0);
                 num_data--;
@@ -750,24 +733,14 @@ static int atmel_spi_next_xfer_dma_submit(struct spi_master *master,
 
         /* prepare the RX dma transfer */
         sg_init_table(&as->dma.sgrx, 1);
-        if (xfer->rx_buf) {
-                as->dma.sgrx.dma_address = xfer->rx_dma + xfer->len - *plen;
-        } else {
-                as->dma.sgrx.dma_address = as->buffer_dma;
-                if (len > BUFFER_SIZE)
-                        len = BUFFER_SIZE;
-        }
+        as->dma.sgrx.dma_address = xfer->rx_dma + xfer->len - *plen;
 
         /* prepare the TX dma transfer */
         sg_init_table(&as->dma.sgtx, 1);
-        if (xfer->tx_buf) {
-                as->dma.sgtx.dma_address = xfer->tx_dma + xfer->len - *plen;
-        } else {
-                as->dma.sgtx.dma_address = as->buffer_dma;
-                if (len > BUFFER_SIZE)
-                        len = BUFFER_SIZE;
-                memset(as->buffer, 0, len);
-        }
+        as->dma.sgtx.dma_address = xfer->tx_dma + xfer->len - *plen;
+
+        if (len > master->max_dma_len)
+                len = master->max_dma_len;
 
         sg_dma_len(&as->dma.sgtx) = len;
         sg_dma_len(&as->dma.sgrx) = len;
@@ -834,25 +807,10 @@ static void atmel_spi_next_xfer_data(struct spi_master *master,
         struct atmel_spi        *as = spi_master_get_devdata(master);
         u32                     len = *plen;
 
-        /* use scratch buffer only when rx or tx data is unspecified */
-        if (xfer->rx_buf)
-                *rx_dma = xfer->rx_dma + xfer->len - *plen;
-        else {
-                *rx_dma = as->buffer_dma;
-                if (len > BUFFER_SIZE)
-                        len = BUFFER_SIZE;
-        }
-
-        if (xfer->tx_buf)
-                *tx_dma = xfer->tx_dma + xfer->len - *plen;
-        else {
-                *tx_dma = as->buffer_dma;
-                if (len > BUFFER_SIZE)
-                        len = BUFFER_SIZE;
-                memset(as->buffer, 0, len);
-                dma_sync_single_for_device(&as->pdev->dev,
-                                as->buffer_dma, len, DMA_TO_DEVICE);
-        }
+        *rx_dma = xfer->rx_dma + xfer->len - *plen;
+        *tx_dma = xfer->tx_dma + xfer->len - *plen;
+        if (len > master->max_dma_len)
+                len = master->max_dma_len;
 
         *plen = len;
 }
@@ -1026,16 +984,12 @@ atmel_spi_pump_single_data(struct atmel_spi *as, struct spi_transfer *xfer)
         u16             *rxp16;
         unsigned long   xfer_pos = xfer->len - as->current_remaining_bytes;
 
-        if (xfer->rx_buf) {
-                if (xfer->bits_per_word > 8) {
-                        rxp16 = (u16 *)(((u8 *)xfer->rx_buf) + xfer_pos);
-                        *rxp16 = spi_readl(as, RDR);
-                } else {
-                        rxp = ((u8 *)xfer->rx_buf) + xfer_pos;
-                        *rxp = spi_readl(as, RDR);
-                }
+        if (xfer->bits_per_word > 8) {
+                rxp16 = (u16 *)(((u8 *)xfer->rx_buf) + xfer_pos);
+                *rxp16 = spi_readl(as, RDR);
         } else {
-                spi_readl(as, RDR);
+                rxp = ((u8 *)xfer->rx_buf) + xfer_pos;
+                *rxp = spi_readl(as, RDR);
         }
         if (xfer->bits_per_word > 8) {
                 if (as->current_remaining_bytes > 2)
@@ -1074,12 +1028,10 @@ atmel_spi_pump_fifo_data(struct atmel_spi *as, struct spi_transfer *xfer)
         /* Read data */
         while (num_data) {
                 rd = spi_readl(as, RDR);
-                if (xfer->rx_buf) {
-                        if (xfer->bits_per_word > 8)
-                                *words++ = rd;
-                        else
-                                *bytes++ = rd;
-                }
+                if (xfer->bits_per_word > 8)
+                        *words++ = rd;
+                else
+                        *bytes++ = rd;
                 num_data--;
         }
 }
@@ -1561,29 +1513,22 @@ static int atmel_spi_probe(struct platform_device *pdev)
         master->bus_num = pdev->id;
         master->num_chipselect = master->dev.of_node ? 0 : 4;
         master->setup = atmel_spi_setup;
+        master->flags = (SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX);
         master->transfer_one_message = atmel_spi_transfer_one_message;
         master->cleanup = atmel_spi_cleanup;
         master->auto_runtime_pm = true;
+        master->max_dma_len = SPI_MAX_DMA_XFER;
         platform_set_drvdata(pdev, master);
 
         as = spi_master_get_devdata(master);
 
-        /*
-         * Scratch buffer is used for throwaway rx and tx data.
-         * It's coherent to minimize dcache pollution.
-         */
-        as->buffer = dma_alloc_coherent(&pdev->dev, BUFFER_SIZE,
-                                        &as->buffer_dma, GFP_KERNEL);
-        if (!as->buffer)
-                goto out_free;
-
         spin_lock_init(&as->lock);
 
         as->pdev = pdev;
         as->regs = devm_ioremap_resource(&pdev->dev, regs);
         if (IS_ERR(as->regs)) {
                 ret = PTR_ERR(as->regs);
-                goto out_free_buffer;
+                goto out_unmap_regs;
         }
         as->phybase = regs->start;
         as->irq = irq;
@@ -1681,9 +1626,6 @@ out_free_dma:
         clk_disable_unprepare(clk);
 out_free_irq:
 out_unmap_regs:
-out_free_buffer:
-        dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer,
-                        as->buffer_dma);
 out_free:
         spi_master_put(master);
         return ret;
@@ -1708,9 +1650,6 @@ static int atmel_spi_remove(struct platform_device *pdev)
         spi_readl(as, SR);
         spin_unlock_irq(&as->lock);
 
-        dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer,
-                        as->buffer_dma);
-
         clk_disable_unprepare(as->clk);
 
         pm_runtime_put_noidle(&pdev->dev);