[PATCH 2/2] memory: ti-k3-fsas: Add TI FSS_FSAS driver

[Santhosh Kumar K <s-k6@ti.com>]

Add a platform driver for the TI Flash SubSystem Application Subsystem
(FSS_FSAS_GENREGS) in K3 SoCs. This driver takes care of disabling the
OSPI XIP prefetch which causes DMA transfer data corruption.

Set SYSCONFIG.DISXIP to disable XIP read prefetch, preventing DMA data
corruption when the OSPI DMA source address is not 4K-aligned.

Signed-off-by: Santhosh Kumar K <s-k6@ti.com>
---
 drivers/memory/Kconfig      | 10 +++++
 drivers/memory/Makefile     |  1 +
 drivers/memory/ti-k3-fsas.c | 74 +++++++++++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+)
 create mode 100644 drivers/memory/ti-k3-fsas.c

diff --git a/drivers/memory/Kconfig b/drivers/memory/Kconfig
index e5527020ff33..954e47810e8d 100644
--- a/drivers/memory/Kconfig
+++ b/drivers/memory/Kconfig
@@ -125,6 +125,16 @@ config TI_EMIF_SRAM
 	  sequence so this driver provides several relocatable PM functions
 	  for the SoC PM code to use.
 
+config TI_K3_FSS_FSAS
+	tristate "TI K3 Flash Subsystem Application Subsystem (FSAS) support"
+	depends on ARCH_K3 || COMPILE_TEST
+	help
+	  Driver for the TI K3 Flash Subsystem Application Subsystem
+	  (FSS_FSAS_GENREGS) wrapper found on K3 related SoCs.
+
+	  This driver takes care of disabling the OSPI XIP prefetch which
+	  causes DMA transfer data corruption.
+
 config FPGA_DFL_EMIF
 	tristate "FPGA DFL EMIF Driver"
 	depends on FPGA_DFL && HAS_IOMEM
diff --git a/drivers/memory/Makefile b/drivers/memory/Makefile
index 3ee883c8759a..8dc4860f615d 100644
--- a/drivers/memory/Makefile
+++ b/drivers/memory/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_STM32_OMM)		+= stm32_omm.o
 obj-$(CONFIG_SAMSUNG_MC)	+= samsung/
 obj-$(CONFIG_TEGRA_MC)		+= tegra/
 obj-$(CONFIG_TI_EMIF_SRAM)	+= ti-emif-sram.o
+obj-$(CONFIG_TI_K3_FSS_FSAS)	+= ti-k3-fsas.o
 obj-$(CONFIG_FPGA_DFL_EMIF)	+= dfl-emif.o
 
 ti-emif-sram-objs		:= ti-emif-pm.o ti-emif-sram-pm.o
diff --git a/drivers/memory/ti-k3-fsas.c b/drivers/memory/ti-k3-fsas.c
new file mode 100644
index 000000000000..9ff109b8d96f
--- /dev/null
+++ b/drivers/memory/ti-k3-fsas.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * TI K3 Flash Subsystem Application Subsystem (FSS_FSAS) driver
+ *
+ * Copyright (C) 2025 Texas Instruments Incorporated - https://www.ti.com
+ */
+
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+
+#define FSAS_GENREGS_SYSCONFIG 0x04
+#define FSAS_SYSCONFIG_DISXIP BIT(7)
+
+struct k3_fsas {
+	void __iomem *base;
+};
+
+static void k3_fsas_disable_xip_prefetch(struct k3_fsas *fsas)
+{
+	u32 val;
+
+	val = readl(fsas->base + FSAS_GENREGS_SYSCONFIG);
+	val |= FSAS_SYSCONFIG_DISXIP;
+	writel(val, fsas->base + FSAS_GENREGS_SYSCONFIG);
+}
+
+static int k3_fsas_probe(struct platform_device *pdev)
+{
+	struct k3_fsas *fsas;
+
+	fsas = devm_kzalloc(&pdev->dev, sizeof(*fsas), GFP_KERNEL);
+	if (!fsas)
+		return -ENOMEM;
+
+	fsas->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(fsas->base))
+		return PTR_ERR(fsas->base);
+
+	platform_set_drvdata(pdev, fsas);
+
+	k3_fsas_disable_xip_prefetch(fsas);
+
+	return 0;
+}
+
+static int k3_fsas_resume(struct device *dev)
+{
+	k3_fsas_disable_xip_prefetch(dev_get_drvdata(dev));
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(k3_fsas_pm_ops, NULL, k3_fsas_resume);
+
+static const struct of_device_id k3_fsas_of_match[] = {
+	{ .compatible = "ti,am62a-fsas" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, k3_fsas_of_match);
+
+static struct platform_driver k3_fsas_driver = {
+	.probe = k3_fsas_probe,
+	.driver = {
+		.name		= "k3-fsas",
+		.of_match_table	= k3_fsas_of_match,
+		.pm		= pm_sleep_ptr(&k3_fsas_pm_ops),
+	},
+};
+module_platform_driver(k3_fsas_driver);
+
+MODULE_DESCRIPTION("TI K3 Flash SubSystem Application Subsystem driver");
+MODULE_LICENSE("GPL");
-- 
2.34.1