linux-kernel - [PATCH] spi: imx: remove CLK calculation and check for target mode

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Message-Id: <20251024055211.408440-1-carlos.song@nxp.com>
Date: Fri, 24 Oct 2025 13:52:11 +0800
From: carlos.song@....com
To: frank.li@....com,
	broonie@...nel.org,
	shawnguo@...nel.org,
	s.hauer@...gutronix.de,
	kernel@...gutronix.de,
	festevam@...il.com
Cc: linux-spi@...r.kernel.org,
	imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] spi: imx: remove CLK calculation and check for target mode

From: Clark Wang <xiaoning.wang@....com>

In target mode, the clock signal is controlled by the master. Target does
not need to check, calculate and configure the clock frequency division.
The target can directly use the root clock to sample the SCL signal.

Therefore, remove check, calculation and frequency division function of
the clock for target mode.

Signed-off-by: Carlos Song <carlos.song@....com>
Signed-off-by: Clark Wang <xiaoning.wang@....com>
---
 drivers/spi/spi-imx.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 4ffee6c5d5c4..6eb4bfb7be4a 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -42,6 +42,7 @@ MODULE_PARM_DESC(polling_limit_us,
 		 "time in us to run a transfer in polling mode\n");
 
 #define MXC_RPM_TIMEOUT		2000 /* 2000ms */
+#define MXC_SPI_DEFAULT_SPEED	500000 /* 500KHz */
 
 #define MXC_CSPIRXDATA		0x00
 #define MXC_CSPITXDATA		0x04
@@ -692,8 +693,11 @@ static int mx51_ecspi_prepare_transfer(struct spi_imx_data *spi_imx,
 	/* set clock speed */
 	ctrl &= ~(0xf << MX51_ECSPI_CTRL_POSTDIV_OFFSET |
 		  0xf << MX51_ECSPI_CTRL_PREDIV_OFFSET);
-	ctrl |= mx51_ecspi_clkdiv(spi_imx, spi_imx->spi_bus_clk, &clk);
-	spi_imx->spi_bus_clk = clk;
+
+	if (!spi_imx->target_mode) {
+		ctrl |= mx51_ecspi_clkdiv(spi_imx, spi_imx->spi_bus_clk, &clk);
+		spi_imx->spi_bus_clk = clk;
+	}
 
 	mx51_configure_cpha(spi_imx, spi);
 
@@ -1316,15 +1320,18 @@ static int spi_imx_setupxfer(struct spi_device *spi,
 	if (!t)
 		return 0;
 
-	if (!t->speed_hz) {
-		if (!spi->max_speed_hz) {
-			dev_err(&spi->dev, "no speed_hz provided!\n");
-			return -EINVAL;
+	if (!spi_imx->target_mode) {
+		if (!t->speed_hz) {
+			if (!spi->max_speed_hz) {
+				dev_err(&spi->dev, "no speed_hz provided!\n");
+				return -EINVAL;
+			}
+			dev_dbg(&spi->dev, "using spi->max_speed_hz!\n");
+			spi_imx->spi_bus_clk = spi->max_speed_hz;
+		} else {
+			spi_imx->spi_bus_clk = t->speed_hz;
 		}
-		dev_dbg(&spi->dev, "using spi->max_speed_hz!\n");
-		spi_imx->spi_bus_clk = spi->max_speed_hz;
-	} else
-		spi_imx->spi_bus_clk = t->speed_hz;
+	}
 
 	spi_imx->bits_per_word = t->bits_per_word;
 	spi_imx->count = t->len;
@@ -1839,6 +1846,7 @@ static int spi_imx_probe(struct platform_device *pdev)
 	controller->prepare_message = spi_imx_prepare_message;
 	controller->unprepare_message = spi_imx_unprepare_message;
 	controller->target_abort = spi_imx_target_abort;
+	spi_imx->spi_bus_clk = MXC_SPI_DEFAULT_SPEED;
 	controller->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_NO_CS |
 				SPI_MOSI_IDLE_LOW;
 
-- 
2.34.1