spi: cadence-quadspi: Disable the SPI before reconfiguring

Observed random DMA timeout failures while doing back to back
transfers which involves switching the modes from DMA to NON-DMA.
This issue is observed while testing the OSPI+UBIFS file system test case
where rootfs is mounted from OSPI UBIFS partition.
To avoid this issue, disable the SPI before changing the configuration
from external DMA to NON-DMA and vice versa and reenable it after changing
the configuration.
As per the Cadence Octal SPI design specification, it is recommended to
disable the Octal-SPI enable bit before reconfiguring.

Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
Link: https://lore.kernel.org/r/20230320095931.2651714-3-sai.krishna.potthuri@amd.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Sai Krishna Potthuri

drivers/spi/spi-cadence-quadspi.c

@@ -791,6 +791,21 @@ static int cqspi_indirect_read_execute(struct cqspi_flash_pdata *f_pdata,
 	return ret;
 }
 
+static void cqspi_controller_enable(struct cqspi_st *cqspi, bool enable)
+{
+	void __iomem *reg_base = cqspi->iobase;
+	unsigned int reg;
+
+	reg = readl(reg_base + CQSPI_REG_CONFIG);
+
+	if (enable)
+		reg |= CQSPI_REG_CONFIG_ENABLE_MASK;
+	else
+		reg &= ~CQSPI_REG_CONFIG_ENABLE_MASK;
+
+	writel(reg, reg_base + CQSPI_REG_CONFIG);
+}
+
 static int cqspi_versal_indirect_read_dma(struct cqspi_flash_pdata *f_pdata,
 					  u_char *rxbuf, loff_t from_addr,
 					  size_t n_rx)
@@ -815,10 +830,14 @@ static int cqspi_versal_indirect_read_dma(struct cqspi_flash_pdata *f_pdata,
 	if (ret)
 		return ret;
 
+	cqspi_controller_enable(cqspi, 0);
+
 	reg = readl(cqspi->iobase + CQSPI_REG_CONFIG);
 	reg |= CQSPI_REG_CONFIG_DMA_MASK;
 	writel(reg, cqspi->iobase + CQSPI_REG_CONFIG);
 
+	cqspi_controller_enable(cqspi, 1);
+
 	dma_addr = dma_map_single(dev, rxbuf, bytes_to_dma, DMA_FROM_DEVICE);
 	if (dma_mapping_error(dev, dma_addr)) {
 		dev_err(dev, "dma mapping failed\n");
@@ -876,10 +895,14 @@ static int cqspi_versal_indirect_read_dma(struct cqspi_flash_pdata *f_pdata,
 	       cqspi->iobase + CQSPI_REG_INDIRECTRD);
 	dma_unmap_single(dev, dma_addr, bytes_to_dma, DMA_FROM_DEVICE);
 
+	cqspi_controller_enable(cqspi, 0);
+
 	reg = readl(cqspi->iobase + CQSPI_REG_CONFIG);
 	reg &= ~CQSPI_REG_CONFIG_DMA_MASK;
 	writel(reg, cqspi->iobase + CQSPI_REG_CONFIG);
 
+	cqspi_controller_enable(cqspi, 1);
+
 	ret = zynqmp_pm_ospi_mux_select(cqspi->pd_dev_id,
 					PM_OSPI_MUX_SEL_LINEAR);
 	if (ret)
@@ -1182,21 +1205,6 @@ static void cqspi_readdata_capture(struct cqspi_st *cqspi,
 	writel(reg, reg_base + CQSPI_REG_READCAPTURE);
 }
 
-static void cqspi_controller_enable(struct cqspi_st *cqspi, bool enable)
-{
-	void __iomem *reg_base = cqspi->iobase;
-	unsigned int reg;
-
-	reg = readl(reg_base + CQSPI_REG_CONFIG);
-
-	if (enable)
-		reg |= CQSPI_REG_CONFIG_ENABLE_MASK;
-	else
-		reg &= ~CQSPI_REG_CONFIG_ENABLE_MASK;
-
-	writel(reg, reg_base + CQSPI_REG_CONFIG);
-}
-
 static void cqspi_configure(struct cqspi_flash_pdata *f_pdata,
 			    unsigned long sclk)
 {