spi: spi-omap2-mcspi: Handle DMA size restriction on AM65x

On AM654, McSPI can only support 4K - 1 bytes per transfer when DMA is
enabled. Therefore populate master->max_transfer_size callback to
inform client drivers of this restriction when DMA channels are
available.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20200204124816.16735-2-vigneshr@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index 7e2292c11d120b44d904c93c7433724a0ea7371e..e9bc9cf984d60b9c7ff0e3c0b9542c9a4567a888 100644 (file)
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/drivers/spi/spi-omap2-mcspi.c
@@ -130,6 +130,7 @@ struct omap2_mcspi {
        int                     fifo_depth;
        bool                    slave_aborted;
        unsigned int            pin_dir:1;
+       size_t                  max_xfer_len;
 };
 
 struct omap2_mcspi_cs {
@@ -1305,6 +1306,18 @@ static bool omap2_mcspi_can_dma(struct spi_master *master,
        return (xfer->len >= DMA_MIN_BYTES);
 }
 
+static size_t omap2_mcspi_max_xfer_size(struct spi_device *spi)
+{
+       struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master);
+       struct omap2_mcspi_dma *mcspi_dma =
+               &mcspi->dma_channels[spi->chip_select];
+
+       if (mcspi->max_xfer_len && mcspi_dma->dma_rx)
+               return mcspi->max_xfer_len;
+
+       return SIZE_MAX;
+}
+
 static int omap2_mcspi_controller_setup(struct omap2_mcspi *mcspi)
 {
        struct spi_master       *master = mcspi->master;
@@ -1373,6 +1386,11 @@ static struct omap2_mcspi_platform_config omap4_pdata = {
        .regs_offset = OMAP4_MCSPI_REG_OFFSET,
 };
 
+static struct omap2_mcspi_platform_config am654_pdata = {
+       .regs_offset = OMAP4_MCSPI_REG_OFFSET,
+       .max_xfer_len = SZ_4K - 1,
+};
+
 static const struct of_device_id omap_mcspi_of_match[] = {
        {
                .compatible = "ti,omap2-mcspi",
@@ -1382,6 +1400,10 @@ static const struct of_device_id omap_mcspi_of_match[] = {
                .compatible = "ti,omap4-mcspi",
                .data = &omap4_pdata,
        },
+       {
+               .compatible = "ti,am654-mcspi",
+               .data = &am654_pdata,
+       },
        { },
 };
 MODULE_DEVICE_TABLE(of, omap_mcspi_of_match);
@@ -1439,6 +1461,10 @@ static int omap2_mcspi_probe(struct platform_device *pdev)
                mcspi->pin_dir = pdata->pin_dir;
        }
        regs_offset = pdata->regs_offset;
+       if (pdata->max_xfer_len) {
+               mcspi->max_xfer_len = pdata->max_xfer_len;
+               master->max_transfer_size = omap2_mcspi_max_xfer_size;
+       }
 
        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        mcspi->base = devm_ioremap_resource(&pdev->dev, r);

diff --git a/include/linux/platform_data/spi-omap2-mcspi.h b/include/linux/platform_data/spi-omap2-mcspi.h
index 0bf9fddb830640dd282c38ee1a001e9c9d2b4f6e..3b400b1919a9bd8a9a446da90e37a3582af15de9 100644 (file)
--- a/include/linux/platform_data/spi-omap2-mcspi.h
+++ b/include/linux/platform_data/spi-omap2-mcspi.h
@@ -11,6 +11,7 @@ struct omap2_mcspi_platform_config {
        unsigned short  num_cs;
        unsigned int regs_offset;
        unsigned int pin_dir:1;
+       size_t max_xfer_len;
 };
 
 struct omap2_mcspi_device_config {