mtd: spi-nor: cadence-quadspi: Provide a way to disable DAC mode

Currently direct access mode is used on platforms that have AHB window
(memory mapped window) larger than flash size. This feature is limited
to TI platforms as non TI platforms have < 1MB of AHB window.
Therefore introduce a driver quirk to disable DAC mode and set it for
non TI compatibles. This is in preparation to move to spi-mem framework
where flash geometry cannot be known.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Acked-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20200601070444.16923-3-vigneshr@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/mtd/spi-nor/controllers/cadence-quadspi.c

@@ -34,6 +34,7 @@
 
 /* Quirks */
 #define CQSPI_NEEDS_WR_DELAY		BIT(0)
+#define CQSPI_DISABLE_DAC_MODE		BIT(1)
 
 /* Capabilities mask */
 #define CQSPI_BASE_HWCAPS_MASK					\
@@ -1261,7 +1262,8 @@ static int cqspi_setup_flash(struct cqspi_st *cqspi, struct device_node *np)
 
 		f_pdata->registered = true;
 
-		if (mtd->size <= cqspi->ahb_size) {
+		if (mtd->size <= cqspi->ahb_size &&
+		    !(ddata->quirks & CQSPI_DISABLE_DAC_MODE)) {
 			f_pdata->use_direct_mode = true;
 			dev_dbg(nor->dev, "using direct mode for %s\n",
 				mtd->name);
@@ -1457,6 +1459,7 @@ static const struct dev_pm_ops cqspi__dev_pm_ops = {
 
 static const struct cqspi_driver_platdata cdns_qspi = {
 	.hwcaps_mask = CQSPI_BASE_HWCAPS_MASK,
+	.quirks = CQSPI_DISABLE_DAC_MODE,
 };
 
 static const struct cqspi_driver_platdata k2g_qspi = {