linux-kernel - [RFC PATCH v2 07/12] spi: cadence-quadspi: add DQS support to read data capture

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Message-ID: <20260113141617.1905039-8-s-k6@ti.com>
Date: Tue, 13 Jan 2026 19:46:12 +0530
From: Santhosh Kumar K <s-k6@...com>
To: <broonie@...nel.org>, <robh@...nel.org>, <krzk+dt@...nel.org>,
	<conor+dt@...nel.org>, <miquel.raynal@...tlin.com>, <richard@....at>,
	<vigneshr@...com>, <tudor.ambarus@...aro.org>, <pratyush@...nel.org>,
	<mwalle@...nel.org>
CC: <linux-spi@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-mtd@...ts.infradead.org>,
	<praneeth@...com>, <u-kumar1@...com>, <p-mantena@...com>, <a-dutta@...com>,
	<s-k6@...com>
Subject: [RFC PATCH v2 07/12] spi: cadence-quadspi: add DQS support to read data capture

Add DQS (Data Strobe) parameter to cqspi_readdata_capture() to control
data capture timing. DQS mode uses a dedicated strobe signal for
improved timing margins in high-speed SPI modes.

Signed-off-by: Santhosh Kumar K <s-k6@...com>
---
 drivers/spi/spi-cadence-quadspi.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index 303064fdfe2c..1d708dde4463 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -186,6 +186,7 @@ struct cqspi_driver_platdata {
 #define CQSPI_REG_READCAPTURE_BYPASS_LSB	0
 #define CQSPI_REG_READCAPTURE_DELAY_LSB		1
 #define CQSPI_REG_READCAPTURE_DELAY_MASK	0xF
+#define CQSPI_REG_READCAPTURE_DQS_LSB		8
 
 #define CQSPI_REG_SIZE				0x14
 #define CQSPI_REG_SIZE_ADDRESS_LSB		0
@@ -451,7 +452,7 @@ static int cqspi_wait_idle(struct cqspi_st *cqspi)
 }
 
 static void cqspi_readdata_capture(struct cqspi_st *cqspi, const bool bypass,
-				   const unsigned int delay)
+				   const bool dqs, const unsigned int delay)
 {
 	void __iomem *reg_base = cqspi->iobase;
 	unsigned int reg;
@@ -469,6 +470,11 @@ static void cqspi_readdata_capture(struct cqspi_st *cqspi, const bool bypass,
 	reg |= (delay & CQSPI_REG_READCAPTURE_DELAY_MASK)
 	       << CQSPI_REG_READCAPTURE_DELAY_LSB;
 
+	if (dqs)
+		reg |= BIT(CQSPI_REG_READCAPTURE_DQS_LSB);
+	else
+		reg &= ~BIT(CQSPI_REG_READCAPTURE_DQS_LSB);
+
 	writel(reg, reg_base + CQSPI_REG_READCAPTURE);
 }
 
@@ -1310,7 +1316,7 @@ static void cqspi_configure(struct cqspi_flash_pdata *f_pdata,
 		cqspi->sclk = sclk;
 		cqspi_config_baudrate_div(cqspi);
 		cqspi_delay(f_pdata);
-		cqspi_readdata_capture(cqspi, !cqspi->rclk_en,
+		cqspi_readdata_capture(cqspi, !cqspi->rclk_en, false,
 				       f_pdata->read_delay);
 	}
 
-- 
2.34.1