spi: dw: Add DMA address widths capability check

Store address width capabilities of DMA controller during init and check
the same per transfer to make sure the bits/word requirement can be met.

Current DW DMA driver requires both tx and rx channel to be configured
and functional hence a subset of both tx and rx channel address width
capability is checked with the width requirement(n_bytes) for a
transfer.

* tested on Baikal-T1 based system with DW SPI-looped back interface
transferring a chunk of data with DFS:8,12,16.

Signed-off-by: Joy Chakraborty <joychakr@google.com
Reviewed-by: Serge Semin <fancer.lancer@gmail.com
Tested-by: Serge Semin <fancer.lancer@gmail.com
Link: https://lore.kernel.org/r/20230512104746.1797865-3-joychakr@google.com
Signed-off-by: Mark Brown <broonie@kernel.org

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
index 2363317..df81965 100644 (file)
--- a/drivers/spi/spi-dw-dma.c
+++ b/drivers/spi/spi-dw-dma.c
@@ -98,6 +98,13 @@ static int dw_spi_dma_caps_init(struct dw_spi *dws)
        else
                dws->dma_sg_burst = 0;
 
+       /*
+        * Assuming both channels belong to the same DMA controller hence the
+        * peripheral side address width capabilities most likely would be
+        * the same.
+        */
+       dws->dma_addr_widths = tx.dst_addr_widths & rx.src_addr_widths;
+
        return 0;
 }
 
@@ -239,8 +246,14 @@ static bool dw_spi_can_dma(struct spi_controller *master,
                           struct spi_device *spi, struct spi_transfer *xfer)
 {
        struct dw_spi *dws = spi_controller_get_devdata(master);
+       enum dma_slave_buswidth dma_bus_width;
+
+       if (xfer->len <= dws->fifo_len)
+               return false;
+
+       dma_bus_width = dw_spi_dma_convert_width(dws->n_bytes);
 
-       return xfer->len > dws->fifo_len;
+       return dws->dma_addr_widths & BIT(dma_bus_width);
 }
 
 static int dw_spi_dma_wait(struct dw_spi *dws, unsigned int len, u32 speed)

diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 9e8eb2b..3962e6d 100644 (file)
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -190,6 +190,7 @@ struct dw_spi {
        struct dma_chan         *rxchan;
        u32                     rxburst;
        u32                     dma_sg_burst;
+       u32                     dma_addr_widths;
        unsigned long           dma_chan_busy;
        dma_addr_t              dma_addr; /* phy address of the Data register */
        const struct dw_spi_dma_ops *dma_ops;