spi: cadence_qspi: Fix OSPI DDR mode alignment issue

If the least significant bit of the address is set to one when
using the DDR protocol for data transfer then the results are
indeterminate for few flash devices. To fix this the least
significant bit of the address is set to zero.

Signed-off-by: Padmarao Begari <padmarao.begari@amd.com>
Link: https://lore.kernel.org/r/20250106095120.800753-1-padmarao.begari@amd.com
Signed-off-by: Michal Simek <michal.simek@amd.com>

diff --git a/drivers/spi/cadence_ospi_versal.c b/drivers/spi/cadence_ospi_versal.c
index dcf28c7..816916d 100644 (file)
--- a/drivers/spi/cadence_ospi_versal.c
+++ b/drivers/spi/cadence_ospi_versal.c
@@ -24,6 +24,13 @@ int cadence_qspi_apb_dma_read(struct cadence_spi_priv *priv,
        u8 opcode, addr_bytes, *rxbuf, dummy_cycles;
 
        n_rx = op->data.nbytes;
+
+       if (op->addr.dtr && (op->addr.val % 2)) {
+               n_rx += 1;
+               writel(op->addr.val & ~0x1,
+                      priv->regbase + CQSPI_REG_INDIRECTRDSTARTADDR);
+       }
+
        rxbuf = op->data.buf.in;
        rx_rem = n_rx % 4;
        bytes_to_dma = n_rx - rx_rem;
@@ -104,6 +111,11 @@ int cadence_qspi_apb_dma_read(struct cadence_spi_priv *priv,
                memcpy(rxbuf, &data, rx_rem);
        }
 
+       if (op->addr.dtr && (op->addr.val % 2)) {
+               rxbuf -= bytes_to_dma;
+               memcpy(rxbuf, rxbuf + 1, n_rx - 1);
+       }
+
        return 0;
 }