[PATCH v7 4/5] spi: dw: Add DMA address widths capability check

Joy Chakraborty
2023-04-18T05:29:40Z

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.

Signed-off-by: Joy Chakraborty <joychakr@google.com>
---
drivers/spi/spi-dw-dma.c | 16 +++++++++++++++-
drivers/spi/spi-dw.h | 1 +
2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
index 22d0727a3789..45980c46946d 100644
--- a/drivers/spi/spi-dw-dma.c
+++ b/drivers/spi/spi-dw-dma.c
@@ -97,6 +97,14 @@ static int dw_spi_dma_caps_init(struct dw_spi *dws)
dws->dma_sg_burst = rx.max_sg_burst;
else
dws->dma_sg_burst = 0;
+
+ /*
+ * Assuming both channels belong to the same DMA controller hence the
+ * address width capabilities most likely would be the same.
+ */
+ dws->dma_addr_widths = tx.dst_addr_widths & rx.src_addr_widths;
+
+ return 0;
}

static int dw_spi_dma_init_mfld(struct device *dev, struct dw_spi *dws)
@@ -237,8 +245,14 @@ 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 9e8eb2b52d5c..3962e6dcf880 100644
--- 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;
--
2.40.0.634.g4ca3ef3211-goog