spi: spi-fsl-dspi: restrict register range for regmap access

[ Upstream commit 283ae0c ]

DSPI registers are NOT continuous, some registers are reserved and
accessing them from userspace will trigger external abort, add regmap
register access table to avoid below abort.

  For example on S32G:

  # cat /sys/kernel/debug/regmap/401d8000.spi/registers

  Internal error: synchronous external abort: 96000210 1 PREEMPT SMP
  ...
  Call trace:
  regmap_mmio_read32le+0x24/0x48
  regmap_mmio_read+0x48/0x70
  _regmap_bus_reg_read+0x38/0x48
  _regmap_read+0x68/0x1b0
  regmap_read+0x50/0x78
  regmap_read_debugfs+0x120/0x338

Fixes: 1acbdeb ("spi/fsl-dspi: Convert to use regmap and add big-endian support")
Co-developed-by: Xulin Sun <[email protected]>
Signed-off-by: Xulin Sun <[email protected]>
Signed-off-by: Larisa Grigore <[email protected]>
Signed-off-by: James Clark <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Mark Brown <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

Author: Larisa Grigore

drivers/spi/spi-fsl-dspi.c

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0+
 //
 // Copyright 2013 Freescale Semiconductor, Inc.
-// Copyright 2020 NXP
+// Copyright 2020-2025 NXP
 //
 // Freescale DSPI driver
 // This file contains a driver for the Freescale DSPI
@@ -1167,6 +1167,20 @@ static int dspi_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(dspi_pm, dspi_suspend, dspi_resume);
 
+static const struct regmap_range dspi_yes_ranges[] = {
+	regmap_reg_range(SPI_MCR, SPI_MCR),
+	regmap_reg_range(SPI_TCR, SPI_CTAR(3)),
+	regmap_reg_range(SPI_SR, SPI_TXFR3),
+	regmap_reg_range(SPI_RXFR0, SPI_RXFR3),
+	regmap_reg_range(SPI_CTARE(0), SPI_CTARE(3)),
+	regmap_reg_range(SPI_SREX, SPI_SREX),
+};
+
+static const struct regmap_access_table dspi_access_table = {
+	.yes_ranges	= dspi_yes_ranges,
+	.n_yes_ranges	= ARRAY_SIZE(dspi_yes_ranges),
+};
+
 static const struct regmap_range dspi_volatile_ranges[] = {
 	regmap_reg_range(SPI_MCR, SPI_TCR),
 	regmap_reg_range(SPI_SR, SPI_SR),
@@ -1184,6 +1198,8 @@ static const struct regmap_config dspi_regmap_config = {
 	.reg_stride	= 4,
 	.max_register	= 0x88,
 	.volatile_table	= &dspi_volatile_table,
+	.rd_table	= &dspi_access_table,
+	.wr_table	= &dspi_access_table,
 };
 
 static const struct regmap_range dspi_xspi_volatile_ranges[] = {
@@ -1205,6 +1221,8 @@ static const struct regmap_config dspi_xspi_regmap_config[] = {
 		.reg_stride	= 4,
 		.max_register	= 0x13c,
 		.volatile_table	= &dspi_xspi_volatile_table,
+		.rd_table	= &dspi_access_table,
+		.wr_table	= &dspi_access_table,
 	},
 	{
 		.name		= "pushr",