[PATCH 0/2] Fix OSPI DMA corruption via FSS_FSAS driver

[PATCH 0/2] Fix OSPI DMA corruption via FSS_FSAS driver

[Santhosh Kumar K]

On TI K3 SoCs, DMA transfers from OSPI produce corrupted data when the
source address is only 4-byte aligned (not 4K-aligned). The root cause
is XIP read prefetch in the FSS_FSAS_GENREGS wrapper (SYSCONFIG.DISXIP,
bit 7), which is enabled by default.

This series adds a dedicated FSS_FSAS platform driver that disables XIP
prefetch at probe, plus the respective DT binding.

Testing:
This series was tested on TI's
AM62Ax SK with OSPI NAND flash and
AM62Px SK with OSPI NOR flash:

Test log: https://gist.github.com/santhosh21/3ac2a0273065e86315a9b442327c9599
Repo: https://github.com/santhosh21/linux/commits/fsas

Signed-off-by: Santhosh Kumar K <s-k6@ti.com>

Santhosh Kumar K (2):
  dt-bindings: memory: Add TI FSS_FSAS binding
  memory: ti-k3-fsas: Add TI FSS_FSAS driver

 .../memory-controllers/ti,am62a-fsas.yaml     | 39 ++++++++++
 drivers/memory/Kconfig                        | 10 +++
 drivers/memory/Makefile                       |  1 +
 drivers/memory/ti-k3-fsas.c                   | 74 +++++++++++++++++++
 4 files changed, 124 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/memory-controllers/ti,am62a-fsas.yaml
 create mode 100644 drivers/memory/ti-k3-fsas.c

-- 
2.34.1

[PATCH 1/2] dt-bindings: memory: Add TI FSS_FSAS binding

[Santhosh Kumar K]

Add DT binding for the TI Flash Subsystem Application Subsystem
(FSS_FSAS_GENREGS) wrapper present in TI K3 SoCs. This block controls
XIP read prefetch for the OSPI controller.

Signed-off-by: Santhosh Kumar K <s-k6@ti.com>
---
 .../memory-controllers/ti,am62a-fsas.yaml     | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/memory-controllers/ti,am62a-fsas.yaml

diff --git a/Documentation/devicetree/bindings/memory-controllers/ti,am62a-fsas.yaml b/Documentation/devicetree/bindings/memory-controllers/ti,am62a-fsas.yaml
new file mode 100644
index 000000000000..81c71ebfb7e1
--- /dev/null
+++ b/Documentation/devicetree/bindings/memory-controllers/ti,am62a-fsas.yaml
@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+# Copyright (C) 2025 Texas Instruments Incorporated
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soc/ti/ti,am62a-fsas.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Texas Instruments K3 Flash SubSystem Application Subsystem (FSS_FSAS)
+
+maintainers:
+  - Santhosh Kumar K <s-k6@ti.com>
+
+description:
+  The FSS_FSAS_GENREGS block is a TI wrapper inside the Flash SubSystem (FSS).
+
+properties:
+  compatible:
+    const: ti,am62a-fsas
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    bus {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        fsas@fc10000 {
+            compatible = "ti,am62a-fsas";
+            reg = <0x00 0x0fc10000 0x00 0x100>;
+        };
+    };
-- 
2.34.1

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

[Santhosh Kumar K]

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

Re: [PATCH 1/2] dt-bindings: memory: Add TI FSS_FSAS binding

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The `$id` field in the YAML binding schema does not match the file's location, which breaks schema cross-referencing and can cause `dt_binding_check` to silently skip validation.
--

commit 54d35a3fdeae166603662fbdb3cac4a24e6c37c1
Author: Santhosh Kumar K <s-k6@ti.com>

dt-bindings: memory: Add TI FSS_FSAS binding

This commit adds a device tree binding for the TI Flash Subsystem
Application Subsystem (FSS_FSAS_GENREGS) wrapper. This wrapper block
is present in TI K3 SoCs and controls XIP read prefetch for the OSPI
controller.

> diff --git a/Documentation/devicetree/bindings/memory-controllers/ti,am62a-fsas.yaml b/Documentation/devicetree/bindings/memory-controllers/ti,am62a-fsas.yaml
> new file mode 100644
> index 0000000000000..81c71ebfb7e13
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/memory-controllers/ti,am62a-fsas.yaml
> @@ -0,0 +1,39 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +# Copyright (C) 2025 Texas Instruments Incorporated
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/soc/ti/ti,am62a-fsas.yaml#

[Severity: Medium]
Does this $id path mismatch the file's actual location?

The file is being added to the memory-controllers subdirectory, but the
$id field specifies soc/ti/. When the $id field does not exactly match
the file path relative to Documentation/devicetree/bindings/, it breaks
schema cross-referencing and can cause dt_binding_check to silently skip
validation or report misleading errors.

> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Texas Instruments K3 Flash SubSystem Application Subsystem (FSS_FSAS)

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260629064228.860226-1-s-k6@ti.com?part=1

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

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Incorrect wrapper macro `pm_sleep_ptr()` used for the `dev_pm_ops` structure pointer.
--

commit be06c2a7e885af5ffba7e5ddc137bd7ba0758747
Author: Santhosh Kumar K <s-k6@ti.com>
memory: ti-k3-fsas: Add TI FSS_FSAS driver

This commit adds a new platform driver for the TI K3 Flash Subsystem
Application Subsystem (FSS_FSAS). It configures the SYSCONFIG register to
disable OSPI XIP prefetch, preventing DMA data corruption.

> diff --git a/drivers/memory/ti-k3-fsas.c b/drivers/memory/ti-k3-fsas.c
> new file mode 100644
> index 0000000000000..9ff109b8d96fd
> --- /dev/null
> +++ b/drivers/memory/ti-k3-fsas.c
[ ... ]
> +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),

[Severity: Low]
Should this use pm_ptr() instead of pm_sleep_ptr() for the dev_pm_ops
structure pointer?

The PM subsystem guidelines specify that pm_sleep_ptr() is intended for the
individual sleep callbacks, while pm_ptr() should be used for the dev_pm_ops
structure pointer itself. While this doesn't cause immediate issues since
the driver currently only uses sleep callbacks, using pm_ptr() here ensures
consistency with standard PM usage and prevents issues if runtime PM
callbacks are added later.

> +	},
> +};
> +module_platform_driver(k3_fsas_driver);

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260629064228.860226-1-s-k6@ti.com?part=2