linux-kernel - [PATCH v2 09/14] spi: spi-fsl-dspi: Use DMA for S32G controller in target mode

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Message-Id: <20250522-james-nxp-spi-v2-9-bea884630cfb@linaro.org>
Date: Thu, 22 May 2025 15:51:38 +0100
From: James Clark <james.clark@...aro.org>
To: Vladimir Oltean <olteanv@...il.com>, Mark Brown <broonie@...nel.org>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Matti Vaittinen <mazziesaccount@...il.com>
Cc: Conor Dooley <conor+dt@...nel.org>, Frank Li <Frank.Li@....com>, 
 Chester Lin <chester62515@...il.com>, Matthias Brugger <mbrugger@...e.com>, 
 Ghennadi Procopciuc <ghennadi.procopciuc@....nxp.com>, 
 NXP S32 Linux Team <s32@....com>, Shawn Guo <shawnguo@...nel.org>, 
 Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, Chao Fu <B44548@...escale.com>, 
 Xiubo Li <Li.Xiubo@...escale.com>, Lukasz Majewski <lukma@...x.de>, 
 linux-spi@...r.kernel.org, imx@...ts.linux.dev, 
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, 
 Vladimir Oltean <vladimir.oltean@....com>, 
 Dan Carpenter <dan.carpenter@...aro.org>, 
 Larisa Grigore <larisa.grigore@....com>, 
 Ciprian Marian Costea <ciprianmarian.costea@....com>, 
 James Clark <james.clark@...aro.org>
Subject: [PATCH v2 09/14] spi: spi-fsl-dspi: Use DMA for S32G controller in
 target mode

From: Larisa Grigore <larisa.grigore@....com>

Switch to DMA for target mode otherwise the controller is too slow to
feed TX FIFO and UNDERFLOW occurs frequently. DMA can work only with 8
and 16 bits per word. 32bits per word is not supported, this is a
hardware limitation, so we keep the controller mode in TCFQ mode.

Signed-off-by: Larisa Grigore <larisa.grigore@....com>
Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@....com>
Signed-off-by: James Clark <james.clark@...aro.org>
---
 drivers/spi/spi-fsl-dspi.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index 24a51267cb4d..db5a2ed66f68 100644
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -139,6 +139,7 @@ enum {
 	MCF5441X,
 	VF610,
 	S32G,
+	S32G_TARGET,
 };
 
 static const struct regmap_range dspi_yes_ranges[] = {
@@ -183,6 +184,7 @@ static const struct regmap_access_table dspi_volatile_table = {
 
 enum {
 	DSPI_REGMAP,
+	S32G_DSPI_REGMAP,
 	DSPI_XSPI_REGMAP,
 	S32G_DSPI_XSPI_REGMAP,
 	DSPI_PUSHR,
@@ -198,6 +200,15 @@ static const struct regmap_config dspi_regmap_config[] = {
 		.rd_table	= &dspi_access_table,
 		.wr_table	= &dspi_access_table,
 	},
+	[S32G_DSPI_REGMAP] = {
+		.reg_bits	= 32,
+		.val_bits	= 32,
+		.reg_stride	= 4,
+		.max_register	= SPI_RXFR4,
+		.volatile_table	= &dspi_volatile_table,
+		.wr_table	= &s32g_dspi_access_table,
+		.rd_table	= &s32g_dspi_access_table,
+	},
 	[DSPI_XSPI_REGMAP] = {
 		.reg_bits	= 32,
 		.val_bits	= 32,
@@ -296,6 +307,12 @@ static const struct fsl_dspi_devtype_data devtype_data[] = {
 		.fifo_size	  = 5,
 		.regmap		  = &dspi_regmap_config[S32G_DSPI_XSPI_REGMAP],
 	},
+	[S32G_TARGET] = {
+		.trans_mode	  = DSPI_DMA_MODE,
+		.max_clock_factor = 1,
+		.fifo_size	  = 5,
+		.regmap		  = &dspi_regmap_config[S32G_DSPI_REGMAP],
+	},
 };
 
 struct fsl_dspi_dma {
@@ -351,6 +368,12 @@ struct fsl_dspi {
 	void (*dev_to_host)(struct fsl_dspi *dspi, u32 rxdata);
 };
 
+static bool is_s32g_dspi(struct fsl_dspi *data)
+{
+	return data->devtype_data == &devtype_data[S32G] ||
+	       data->devtype_data == &devtype_data[S32G_TARGET];
+}
+
 static void dspi_native_host_to_dev(struct fsl_dspi *dspi, u32 *txdata)
 {
 	switch (dspi->oper_word_size) {
@@ -1426,6 +1449,9 @@ static int dspi_probe(struct platform_device *pdev)
 		dspi->pushr_tx = 0;
 	}
 
+	if (spi_controller_is_target(ctlr) && is_s32g_dspi(dspi))
+		dspi->devtype_data = &devtype_data[S32G_TARGET];
+
 	if (dspi->devtype_data->trans_mode == DSPI_XSPI_MODE)
 		ctlr->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
 	else

-- 
2.34.1