[PATCH v4 4/6] mtd: spi-nor: cadence-quadspi: Add support to enable loop-back clock circuit

[Vignesh R]

Cadence QSPI IP has a adapted loop-back circuit which can be enabled by
setting BYPASS field to 0 in READCAPTURE register. It enables use of
QSPI return clock to latch the data rather than the internal QSPI
reference clock. For high speed operations, adapted loop-back circuit
using QSPI return clock helps to increase data valid window.

Based on DT parameter cdns,rclk-en enable adapted loop-back circuit
for boards which do have QSPI return clock provided.
This patch also modifies cqspi_readdata_capture() function's bypass
parameter to bool to match how its used in the function.

Signed-off-by: Vignesh R <vigne...@ti.com>
---
 drivers/mtd/spi-nor/cadence-quadspi.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c 
b/drivers/mtd/spi-nor/cadence-quadspi.c
index 5cd5d6f7303f..d9629e8f4798 100644
--- a/drivers/mtd/spi-nor/cadence-quadspi.c
+++ b/drivers/mtd/spi-nor/cadence-quadspi.c
@@ -78,6 +78,7 @@ struct cqspi_st {
        bool                    is_decoded_cs;
        u32                     fifo_depth;
        u32                     fifo_width;
+       bool                    rclk_en;
        u32                     trigger_address;
        u32                     wr_delay;
        struct cqspi_flash_pdata f_pdata[CQSPI_MAX_CHIPSELECT];
@@ -788,7 +789,7 @@ static void cqspi_config_baudrate_div(struct cqspi_st 
*cqspi)
 }
 
 static void cqspi_readdata_capture(struct cqspi_st *cqspi,
-                                  const unsigned int bypass,
+                                  const bool bypass,
                                   const unsigned int delay)
 {
        void __iomem *reg_base = cqspi->iobase;
@@ -852,7 +853,8 @@ static void cqspi_configure(struct spi_nor *nor)
                cqspi->sclk = sclk;
                cqspi_config_baudrate_div(cqspi);
                cqspi_delay(nor);
-               cqspi_readdata_capture(cqspi, 1, f_pdata->read_delay);
+               cqspi_readdata_capture(cqspi, !cqspi->rclk_en,
+                                      f_pdata->read_delay);
        }
 
        if (switch_cs || switch_ck)
@@ -1049,6 +1051,8 @@ static int cqspi_of_get_pdata(struct platform_device 
*pdev)
                return -ENXIO;
        }
 
+       cqspi->rclk_en = of_property_read_bool(np, "cdns,rclk-en");
+
        return 0;
 }
 
-- 
2.14.1