[PATCH 0/2] Add Altera timeout bridge driver

[PATCH 0/2] Add Altera timeout bridge driver

[Vyacheslav Yurkov via B4 Relay]

This series adds support for the Altera timeout bridge IP. 

The timeout bridge connects an Avalon bus to the HPS and provides a
downstream address space for devices implemented in the FPGA. The
bridge also exposes status information and generates an interrupt when
a timeout occurs.

The driver registers the timeout bridge as a bus and allows child
devices behind the bridge to be described as the child nodes in the
device tree.

The latest bridge documentation (as of October 2026):
https://docs.altera.com/r/docs/683609/26.1/quartus-prime-pro-edition-user-guide/axi-timeout-bridge-ip

Signed-off-by: Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>
---
Vyacheslav Yurkov (2):
      dt-bindings: bus: Add binding for Altera AXI Timeout Bridge
      bus: add Altera timeout bridge driver

 .../bindings/bus/altera-timeout-bridge.yaml        |  82 ++++++++
 drivers/bus/Kconfig                                |  10 +
 drivers/bus/Makefile                               |   1 +
 drivers/bus/altera-timeout-bridge.c                | 219 +++++++++++++++++++++
 4 files changed, 312 insertions(+)
---
base-commit: a74306e2e676f9775457366fc047a660fbf02f26
change-id: 20261003-feature-timeout-ip-7a93630de299

Best regards,
-- 
Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>

[PATCH 1/2] dt-bindings: bus: Add binding for Altera AXI Timeout Bridge

[Vyacheslav Yurkov via B4 Relay]

From: Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>

Add a device tree binding for the Altera timeout bridge, which connects
an Avalon bus to the HPS and provides an address space for child
devices with a fall back to a simple bus.

Signed-off-by: Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>
---
 .../bindings/bus/altera-timeout-bridge.yaml        | 82 ++++++++++++++++++++++
 1 file changed, 82 insertions(+)

diff --git a/Documentation/devicetree/bindings/bus/altera-timeout-bridge.yaml b/Documentation/devicetree/bindings/bus/altera-timeout-bridge.yaml
new file mode 100644
index 000000000000..b57a0966ba6e
--- /dev/null
+++ b/Documentation/devicetree/bindings/bus/altera-timeout-bridge.yaml
@@ -0,0 +1,82 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/bus/altera-timeout-bridge.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Altera Timeout Bridge
+
+maintainers:
+  - Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>
+
+description: |
+  Altera timeout bridge bus.
+
+properties:
+  compatible:
+    items:
+      - const: altera-timeout-bridge
+      - const: simple-bus
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  ranges: true
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - interrupt-parent
+  - ranges
+  - "#address-cells"
+  - "#size-cells"
+
+patternProperties:
+  "^[a-zA-Z][a-zA-Z0-9,+._-]*@[0-9a-f]+$":
+    type: object
+    description: |
+      Device connected to the timeout bridge.
+
+    required:
+      - compatible
+      - reg
+
+    additionalProperties: true
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    intc: interrupt-controller {
+        interrupt-controller;
+        #interrupt-cells = <3>;
+    };
+
+    timeout_bridge_hps@10000 {
+        compatible = "altera-timeout-bridge", "simple-bus";
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        reg = <0x10000 0xF>;
+
+        interrupts = <0 12 IRQ_TYPE_LEVEL_HIGH>;
+        interrupt-parent = <&intc>;
+
+        ranges = <0x0 0x10010 0x1000>;
+
+        timeout-device@100 {
+            compatible = "timeout-device";
+            reg = <0x100 0x10>;
+        };
+    };

-- 
2.34.1

[PATCH 2/2] bus: add Altera timeout bridge driver

[Vyacheslav Yurkov via B4 Relay]

From: Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>

Add support for the Altera timeout bridge IP.

The bridge connects an Avalon bus to the HPS and monitors accesses for
timeouts. When a timeout occurs the interrupt communicates the event via
sysfs, which user space can monitor to handle it accordingly. The
address with the timeout is reported as well.

Signed-off-by: Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>
---
 drivers/bus/Kconfig                 |  10 ++
 drivers/bus/Makefile                |   1 +
 drivers/bus/altera-timeout-bridge.c | 219 ++++++++++++++++++++++++++++++++++++
 3 files changed, 230 insertions(+)

diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index e4b1db809187..8a4ad96742e5 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -247,6 +247,16 @@ config DA8XX_MSTPRI
 	  configuration. Allows to adjust the priorities of all master
 	  peripherals.
 
+config ALTERA_TIMEOUT_BRIDGE
+	tristate "Altera AXI Timeout Bridge bus"
+	depends on OF
+	default n
+	help
+	  Driver for Altera AXI Timeout Bridge, which can be used a bus.
+	  The subordinate devices can be connected to the bridge, which
+	  detects frozen read/write requests and notifies user space by
+	  means of a sysfs interrupt flag.
+
 source "drivers/bus/fsl-mc/Kconfig"
 source "drivers/bus/mhi/Kconfig"
 
diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index a01f97fef3e8..ad4e6d7b1e49 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -39,6 +39,7 @@ obj-$(CONFIG_UNIPHIER_SYSTEM_BUS)	+= uniphier-system-bus.o
 obj-$(CONFIG_VEXPRESS_CONFIG)	+= vexpress-config.o
 
 obj-$(CONFIG_DA8XX_MSTPRI)	+= da8xx-mstpri.o
+obj-$(CONFIG_ALTERA_TIMEOUT_BRIDGE)	+= altera-timeout-bridge.o
 
 # MHI
 obj-y				+= mhi/
diff --git a/drivers/bus/altera-timeout-bridge.c b/drivers/bus/altera-timeout-bridge.c
new file mode 100644
index 000000000000..bb44ff4a7591
--- /dev/null
+++ b/drivers/bus/altera-timeout-bridge.c
@@ -0,0 +1,219 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Altera Timeout Bridge Bus Driver
+ *
+ * Copyright (C) 2026 Bruker Corporation
+ */
+
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+
+#define ALTERA_TIMEOUT_BRIDGE_REG_TIMED_OUT_ADDRESS 0x08
+#define ALTERA_TIMEOUT_BRIDGE_REG_IRQ_STATUS_RESET 0x00
+
+struct altera_timeout_bridge_data {
+	struct device *dev;
+	struct resource *bridge_register_resource;
+	void __iomem *bridge_registers;
+	atomic_t irq_count;
+	struct kernfs_node *irq_node;
+};
+
+static ssize_t timeout_irq_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	return 0;
+}
+
+static ssize_t irq_count_show(struct device *dev,
+			      struct device_attribute *attr,
+			      char *buf)
+{
+	struct altera_timeout_bridge_data *driver_data = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%d\n", atomic_read(&driver_data->irq_count));
+}
+
+static DEVICE_ATTR_RO(timeout_irq);
+static DEVICE_ATTR_RO(irq_count);
+
+static struct attribute *altera_timeout_bridge_sysfs_attrs[] = {
+	&dev_attr_timeout_irq.attr,
+	&dev_attr_irq_count.attr,
+	NULL /* sentinel */
+};
+
+static const struct attribute_group altera_timeout_bridge_sysfs_group = {
+	.attrs = altera_timeout_bridge_sysfs_attrs,
+};
+
+static u32
+bridge_reg_read(struct altera_timeout_bridge_data *driver_data,
+		u32 offset)
+{
+	u32 result;
+
+	result = readl(driver_data->bridge_registers + offset);
+
+	return result;
+}
+
+static void bridge_reg_write(
+	struct altera_timeout_bridge_data *driver_data,
+	int offset, u32 value)
+{
+	writel(value, driver_data->bridge_registers + offset);
+}
+
+static irqreturn_t altera_timeout_bridge_isr(int irq, void *data)
+{
+	struct altera_timeout_bridge_data *driver_data = data;
+	u32 timed_out_address;
+	resource_size_t effective_base_address;
+	resource_size_t effective_timed_out_address;
+
+	atomic_inc(&driver_data->irq_count);
+
+	// Read and print the timed-out address (encoded in the lower nibble
+	// 0x8..0xF according to AXI Timeout Bridge IP (CSR Interrupt Status Information)
+	timed_out_address = bridge_reg_read(
+		driver_data,
+		ALTERA_TIMEOUT_BRIDGE_REG_TIMED_OUT_ADDRESS);
+	effective_base_address = driver_data->bridge_register_resource->start;
+	effective_timed_out_address = effective_base_address + timed_out_address;
+	pr_err("%s: timeout at address 0x%llx\n",
+		__func__, (unsigned long long)effective_timed_out_address);
+
+	// Reset IRQ status in the bridge
+	bridge_reg_write(
+		driver_data,
+		ALTERA_TIMEOUT_BRIDGE_REG_IRQ_STATUS_RESET,
+		0x1);
+	// notify the user space
+	sysfs_notify_dirent(driver_data->irq_node);
+
+	return IRQ_HANDLED;
+}
+static int altera_timeout_bridge_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct of_device_id *match;
+	const struct of_dev_auxdata *lookup = dev_get_platdata(dev);
+	struct device_node *np = dev->of_node;
+	struct altera_timeout_bridge_data *driver_data;
+	int ret = 0;
+	int irq = -1;
+
+	/*
+	 * Allow user to use driver_override to bind this driver to a
+	 * transparent bus device which has a different compatible string
+	 * that's not listed in simple_pm_bus_of_match. We don't want to do any
+	 * of the simple-pm-bus tasks for these devices, so return early.
+	 */
+	if (device_has_driver_override(&pdev->dev))
+		return 0;
+
+	match = of_match_device(dev->driver->of_match_table, dev);
+
+	/* Use a fall back logic like in simple-pm-bus */
+	if (match && match->data) {
+		if (of_property_match_string(np, "compatible", match->compatible) == 0)
+			return 0;
+		else
+			return -ENODEV;
+	}
+
+	driver_data =
+		devm_kzalloc(&pdev->dev, sizeof(*driver_data), GFP_KERNEL);
+	if (!driver_data) {
+		dev_err(&pdev->dev,
+			"%s: kzalloc failed: no memory for the driver's data, returning ENOMEM\n",
+			__func__);
+		return -ENOMEM;
+	}
+
+	driver_data->dev = dev;
+	platform_set_drvdata(pdev, driver_data);
+
+	driver_data->bridge_register_resource =
+		platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!driver_data->bridge_register_resource) {
+		dev_err(dev,
+			"%s: missing required reg binding\n",
+			__func__);
+		return -ENOENT;
+	}
+	driver_data->bridge_registers =
+		devm_ioremap_resource(dev,
+				     driver_data->bridge_register_resource);
+	if (IS_ERR(driver_data->bridge_registers)) {
+		dev_err(dev,
+			"%s: ioremap_resource failed for bridge-status MMIO, returning PTR_ERR(%ld)\n",
+			__func__, PTR_ERR(driver_data->bridge_registers));
+		return PTR_ERR(driver_data->bridge_registers);
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(dev,
+			"%s: platform_get_irq failed: %d\n", __func__, irq);
+		return irq;
+	}
+
+	ret = devm_request_irq(dev, irq,
+			       altera_timeout_bridge_isr,
+			       0,
+			       dev_name(dev),
+			       driver_data);
+	if (ret) {
+		dev_err(dev,
+			"%s: devm_request_irq failed for IRQ %d: %d\n",
+			__func__, irq, ret);
+		return ret;
+	}
+
+	ret = devm_device_add_group(dev, &altera_timeout_bridge_sysfs_group);
+	if (ret)
+		return ret;
+
+	driver_data->irq_node = sysfs_get_dirent(dev->kobj.sd, "timeout_irq");
+	if (!driver_data->irq_node)
+		return -ENOENT;
+
+	ret = devm_add_action_or_reset(dev, (void (*)(void *))sysfs_put, driver_data->irq_node);
+	if (ret)
+		return ret;
+
+	if (np)
+		of_platform_populate(np, NULL, lookup, &pdev->dev);
+
+	return 0;
+}
+
+#define ONLY_BUS	((void *) 1) /* Match if the device is only a bus. */
+
+static const struct of_device_id altera_timeout_bridge_of_match[] = {
+	{ .compatible = "altera-timeout-bridge", },
+	{ .compatible = "simple-bus",	.data = ONLY_BUS },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, altera_timeout_bridge_of_match);
+
+static struct platform_driver altera_timeout_bridge_driver = {
+	.probe = altera_timeout_bridge_probe,
+	.driver = {
+		.name = "altera-timeout-bridge",
+		.of_match_table = altera_timeout_bridge_of_match,
+	},
+};
+
+module_platform_driver(altera_timeout_bridge_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Avalon Timeout Bridge Bus");
+MODULE_AUTHOR("Vyacheslav Yurkov (V.Yurkov.EXT@bruker.com)");
+

-- 
2.34.1

Re: [PATCH 1/2] dt-bindings: bus: Add binding for Altera AXI Timeout Bridge

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 4 potential issue(s) to consider:
- [Medium] dt-bindings: invalid compatible string format altera-timeout-bridge
- [Medium] dt-bindings: erroneous required interrupt-parent breaks inheritance
- [Low] dt-bindings: example node name uses underscores instead of hyphens
- [Low] dt-bindings: unaligned 15-byte reg size in example
--

commit 2cd126fb35ab7ef8e7fe6463a8fed9d0a99d2108
Author: Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>

dt-bindings: bus: Add binding for Altera AXI Timeout Bridge

This commit adds a device tree binding for the Altera timeout bridge, which
connects an Avalon bus to the HPS and provides an address space for child
devices.

> diff --git a/Documentation/devicetree/bindings/bus/altera-timeout-bridge.yaml b/Documentation/devicetree/bindings/bus/altera-timeout-bridge.yaml
> new file mode 100644
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/bus/altera-timeout-bridge.yaml
> @@ -0,0 +1,82 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/bus/altera-timeout-bridge.yaml#

[Severity: Medium]
Does this $id field inherit an incorrectly formatted prefix and missing comma
from the filename? The compatible string issues mentioned below seem to have
propagated to both the filename and this path reference.

[ ... ]

> +properties:
> +  compatible:
> +    items:
> +      - const: altera-timeout-bridge

[Severity: Medium]
Does this compatible string violate the standard device tree specification
that mandates the '<vendor>,<device>' format? The standard vendor prefix
for Altera is 'altr', not 'altera', and the missing comma separator breaks
standard pattern matching.

[ ... ]

> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - interrupt-parent

[Severity: Medium]
Should 'interrupt-parent' be explicitly required here? By explicitly listing
it as a required property, the schema mandates that every instantiated node
must define it. Does this violate standard Device Tree structural inheritance,
where interrupt routing is inherited from parent nodes?

[ ... ]

> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    intc: interrupt-controller {
> +        interrupt-controller;
> +        #interrupt-cells = <3>;
> +    };
> +
> +    timeout_bridge_hps@10000 {

[Severity: Low]
This isn't a functional bug, but the example node name uses underscores
instead of hyphens. Could this trigger dtc W=1 warnings by violating standard
Device Tree naming conventions?

> +        compatible = "altera-timeout-bridge", "simple-bus";
> +        #address-cells = <1>;
> +        #size-cells = <1>;
> +
> +        reg = <0x10000 0xF>;

[Severity: Low]
Is this 15-byte window size intentional? MMIO regions are universally aligned
to word (4-byte) boundaries, meaning a 15-byte window truncates the final
32-bit register space (ending at 15 instead of 16). Could this be a typo
for 0x10?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261003-feature-timeout-ip-v1-0-8837c311d571@bruker.com?part=1

Re: [PATCH 2/2] bus: add Altera timeout bridge driver

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 7 potential issue(s) to consider:
- [High] bus: UAF of irq_node during teardown or early interrupt
- [High] bus: CFI violation in devres teardown due to mismatched function pointer cast
- [High] bus: driver incorrectly claims simple-bus devices, breaking power management
- [Medium] bus: bypassed hardware initialization when bound via driver_override
- [Medium] bus: leaked child devices due to missing depopulation on driver remove
- [Medium] bus: incorrectly adds physical base address to timeout address
- [Medium] bus: un-rate-limited error logging in ISR causes kernel log flooding
--

commit c74336cb2c00c16659c7f03c8c51687597e67ab5
Author: Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>
Subject: bus: add Altera timeout bridge driver

Add support for the Altera timeout bridge IP. The bridge connects an Avalon
bus to the HPS and monitors accesses for timeouts. When a timeout occurs
the interrupt communicates the event via sysfs.

> diff --git a/drivers/bus/altera-timeout-bridge.c b/drivers/bus/altera-timeout-bridge.c
> new file mode 100644
> index 0000000000000..bb44ff4a75910
> --- /dev/null
> +++ b/drivers/bus/altera-timeout-bridge.c
> @@ -0,0 +1,219 @@

[ ... ]

> +static irqreturn_t altera_timeout_bridge_isr(int irq, void *data)
> +{
> +	struct altera_timeout_bridge_data *driver_data = data;
> +	u32 timed_out_address;
> +	resource_size_t effective_base_address;
> +	resource_size_t effective_timed_out_address;
> +
> +	atomic_inc(&driver_data->irq_count);
> +
> +	// Read and print the timed-out address (encoded in the lower nibble
> +	// 0x8..0xF according to AXI Timeout Bridge IP (CSR Interrupt Status Information)
> +	timed_out_address = bridge_reg_read(
> +		driver_data,
> +		ALTERA_TIMEOUT_BRIDGE_REG_TIMED_OUT_ADDRESS);
> +	effective_base_address = driver_data->bridge_register_resource->start;
> +	effective_timed_out_address = effective_base_address + timed_out_address;

[Severity: Medium]
Does this calculation corrupt the actual timed-out AXI address by erroneously
adding the driver's own register base?

> +	pr_err("%s: timeout at address 0x%llx\n",
> +		__func__, (unsigned long long)effective_timed_out_address);

[Severity: Medium]
Will this synchronous pr_err() statement flood the kernel log if the hardware
triggers continuous faults?

> +
> +	// Reset IRQ status in the bridge
> +	bridge_reg_write(
> +		driver_data,
> +		ALTERA_TIMEOUT_BRIDGE_REG_IRQ_STATUS_RESET,
> +		0x1);
> +	// notify the user space
> +	sysfs_notify_dirent(driver_data->irq_node);

[Severity: High]
Can this sysfs_notify_dirent() dereference an uninitialized or freed
irq_node?

During probe, devm_request_irq() is called before driver_data->irq_node is
initialized, leaving a window where early interrupts see a NULL pointer.
Additionally, because the devres action to free irq_node is registered after
the interrupt request, devres executes in LIFO order and frees irq_node
before the interrupt is disabled during teardown.

> +
> +	return IRQ_HANDLED;
> +}
> +static int altera_timeout_bridge_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	const struct of_device_id *match;
> +	const struct of_dev_auxdata *lookup = dev_get_platdata(dev);
> +	struct device_node *np = dev->of_node;
> +	struct altera_timeout_bridge_data *driver_data;
> +	int ret = 0;
> +	int irq = -1;
> +
> +	/*
> +	 * Allow user to use driver_override to bind this driver to a
> +	 * transparent bus device which has a different compatible string
> +	 * that's not listed in simple_pm_bus_of_match. We don't want to do any
> +	 * of the simple-pm-bus tasks for these devices, so return early.
> +	 */
> +	if (device_has_driver_override(&pdev->dev))
> +		return 0;

[Severity: Medium]
Does this check incorrectly bypass the entire hardware initialization logic
if a driver override is used?

If a user explicitly binds the driver to a device via the driver_override
sysfs attribute, the probe function immediately returns 0, skipping all
memory allocations, register mappings, and interrupt requests.

> +
> +	match = of_match_device(dev->driver->of_match_table, dev);
> +
> +	/* Use a fall back logic like in simple-pm-bus */
> +	if (match && match->data) {
> +		if (of_property_match_string(np, "compatible", match->compatible) == 0)
> +			return 0;

[Severity: High]
Does this cause the driver to incorrectly claim generic system buses and break
power management?

The driver's OF match table includes the generic "simple-bus" compatible
string. Returning 0 here prevents the correct simple-pm-bus driver from
binding to these buses, which is responsible for enabling their power domains
and clocks, breaking all child devices on the bus.

> +		else
> +			return -ENODEV;
> +	}

[ ... ]

> +	ret = devm_request_irq(dev, irq,
> +			       altera_timeout_bridge_isr,
> +			       0,
> +			       dev_name(dev),
> +			       driver_data);
> +	if (ret) {
> +		dev_err(dev,
> +			"%s: devm_request_irq failed for IRQ %d: %d\n",
> +			__func__, irq, ret);
> +		return ret;
> +	}
> +
> +	ret = devm_device_add_group(dev, &altera_timeout_bridge_sysfs_group);
> +	if (ret)
> +		return ret;
> +
> +	driver_data->irq_node = sysfs_get_dirent(dev->kobj.sd, "timeout_irq");
> +	if (!driver_data->irq_node)
> +		return -ENOENT;
> +
> +	ret = devm_add_action_or_reset(dev, (void (*)(void *))sysfs_put, driver_data->irq_node);

[Severity: High]
Does this mismatched function pointer cast cause a Control-Flow Integrity
(CFI) violation during devres teardown?

The driver registers sysfs_put() with devm_add_action_or_reset() by casting
it to (void (*)(void *)). The actual signature of sysfs_put() expects a
struct kernfs_node *, not void *. When devres executes this action on module
unload or probe failure, KCFI detects the signature mismatch and panics.

> +	if (ret)
> +		return ret;
> +
> +	if (np)
> +		of_platform_populate(np, NULL, lookup, &pdev->dev);
> +
> +	return 0;
> +}

[Severity: Medium]
Are these child devices leaked when the driver is unbound?

During probe, of_platform_populate() creates child platform devices. However,
the platform driver lacks a .remove callback and does not use
devm_of_platform_populate(). The child devices are never destroyed when the
driver is unbound.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261003-feature-timeout-ip-v1-0-8837c311d571@bruker.com?part=2

Re: [PATCH 1/2] dt-bindings: bus: Add binding for Altera AXI Timeout Bridge

[Krzysztof Kozlowski]

On 03/10/2026 22:19, Vyacheslav Yurkov via B4 Relay wrote:
> From: Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>
> 
> Add a device tree binding for the Altera timeout bridge, which connects
> an Avalon bus to the HPS and provides an address space for child
> devices with a fall back to a simple bus.
> 
> Signed-off-by: Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>
> ---
>  .../bindings/bus/altera-timeout-bridge.yaml        | 82 ++++++++++++++++++++++

Filename must match compatible and compatible has completely broken
format. Please look at DT spec or any other examples how compatibles are
created.


>  1 file changed, 82 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/bus/altera-timeout-bridge.yaml b/Documentation/devicetree/bindings/bus/altera-timeout-bridge.yaml
> new file mode 100644
> index 000000000000..b57a0966ba6e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/bus/altera-timeout-bridge.yaml
> @@ -0,0 +1,82 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/bus/altera-timeout-bridge.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Altera Timeout Bridge
> +
> +maintainers:
> +  - Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>
> +
> +description: |
> +  Altera timeout bridge bus.

Useless description. You keep repeating the same.

> +
> +properties:
> +  compatible:
> +    items:
> +      - const: altera-timeout-bridge
> +      - const: simple-bus

Why the fallback?

Your commit msg is also useless here, you just wrote what you did, not why.

I see no reason why generic "bus" like that should stay generic,
although you have entire commit msg to explain why this is different or
what is the versioning of this IP block.

Missing blank line.

> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  ranges: true
> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 1
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - interrupt-parent
> +  - ranges
> +  - "#address-cells"
> +  - "#size-cells"
> +
> +patternProperties:

This follows properties.

> +  "^[a-zA-Z][a-zA-Z0-9,+._-]*@[0-9a-f]+$":
> +    type: object
> +    description: |
> +      Device connected to the timeout bridge.
> +
> +    required:
> +      - compatible
> +      - reg
> +
> +    additionalProperties: true
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    intc: interrupt-controller {
> +        interrupt-controller;
> +        #interrupt-cells = <3>;
> +    };

Drop, irrelevant


> +
> +    timeout_bridge_hps@10000 {

Really, this is the style you send? So the toolset - dt-check-style - or
the Coding style mean nothing and you keep sending what you have in
downstream.



Best regards,
Krzysztof

Re: [PATCH 2/2] bus: add Altera timeout bridge driver

[Krzysztof Kozlowski]

On 03/10/2026 22:19, Vyacheslav Yurkov via B4 Relay wrote:
> From: Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>
> 
> Add support for the Altera timeout bridge IP.
> 
> The bridge connects an Avalon bus to the HPS and monitors accesses for
> timeouts. When a timeout occurs the interrupt communicates the event via
> sysfs, which user space can monitor to handle it accordingly. The
> address with the timeout is reported as well.
> 

Neither this nor binding explains what is this hardware and where I can
find it.

> Signed-off-by: Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>
> ---
>  drivers/bus/Kconfig                 |  10 ++
>  drivers/bus/Makefile                |   1 +
>  drivers/bus/altera-timeout-bridge.c | 219 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 230 insertions(+)
> 
> diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
> index e4b1db809187..8a4ad96742e5 100644
> --- a/drivers/bus/Kconfig
> +++ b/drivers/bus/Kconfig
> @@ -247,6 +247,16 @@ config DA8XX_MSTPRI
>  	  configuration. Allows to adjust the priorities of all master
>  	  peripherals.
>  
> +config ALTERA_TIMEOUT_BRIDGE
> +	tristate "Altera AXI Timeout Bridge bus"
> +	depends on OF
> +	default n
> +	help
> +	  Driver for Altera AXI Timeout Bridge, which can be used a bus.
> +	  The subordinate devices can be connected to the bridge, which
> +	  detects frozen read/write requests and notifies user space by
> +	  means of a sysfs interrupt flag.




> +
> +static ssize_t irq_count_show(struct device *dev,
> +			      struct device_attribute *attr,
> +			      char *buf)
> +{
> +	struct altera_timeout_bridge_data *driver_data = dev_get_drvdata(dev);
> +
> +	return sysfs_emit(buf, "%d\n", atomic_read(&driver_data->irq_count));
> +}
> +
> +static DEVICE_ATTR_RO(timeout_irq);
> +static DEVICE_ATTR_RO(irq_count);

Missing ABI documentation.


> +


> +
> +#define ONLY_BUS	((void *) 1) /* Match if the device is only a bus. */
> +
> +static const struct of_device_id altera_timeout_bridge_of_match[] = {
> +	{ .compatible = "altera-timeout-bridge", },
> +	{ .compatible = "simple-bus",	.data = ONLY_BUS },

I don't understand why you want to bind to generic compatible.



> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, altera_timeout_bridge_of_match);
> +
> +static struct platform_driver altera_timeout_bridge_driver = {
> +	.probe = altera_timeout_bridge_probe,
> +	.driver = {
> +		.name = "altera-timeout-bridge",
> +		.of_match_table = altera_timeout_bridge_of_match,
> +	},
> +};
> +
> +module_platform_driver(altera_timeout_bridge_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Avalon Timeout Bridge Bus");
> +MODULE_AUTHOR("Vyacheslav Yurkov (V.Yurkov.EXT@bruker.com)");
> +
> 


Best regards,
Krzysztof

Re: [PATCH 2/2] bus: add Altera timeout bridge driver

[kernel test robot]

Hi Vyacheslav,

kernel test robot noticed the following build errors:

[auto build test ERROR on a74306e2e676f9775457366fc047a660fbf02f26]

url:    https://github.com/intel-lab-lkp/linux/commits/Vyacheslav-Yurkov-via-B4-Relay/dt-bindings-bus-Add-binding-for-Altera-AXI-Timeout-Bridge/20261003-201919
base:   a74306e2e676f9775457366fc047a660fbf02f26
patch link:    https://lore.kernel.org/r/20261003-feature-timeout-ip-v1-2-8837c311d571%40bruker.com
patch subject: [PATCH 2/2] bus: add Altera timeout bridge driver
config: s390-allmodconfig (https://download.01.org/0day-ci/archive/20261005/202610050325.ZOPvf8XR-lkp@intel.com/config)
compiler: clang version 24.0.0git (https://github.com/llvm/llvm-project 5f609f950d2e80addf5566623013db68394334db)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20261005/202610050325.ZOPvf8XR-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202610050325.ZOPvf8XR-lkp@intel.com/

All error/warnings (new ones prefixed by >>):

>> drivers/bus/altera-timeout-bridge.c:60:11: error: call to undeclared function 'readl'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
      60 |         result = readl(driver_data->bridge_registers + offset);
         |                  ^
>> drivers/bus/altera-timeout-bridge.c:69:2: error: call to undeclared function 'writel'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
      69 |         writel(value, driver_data->bridge_registers + offset);
         |         ^
>> drivers/bus/altera-timeout-bridge.c:187:38: warning: cast from 'void (*)(struct kernfs_node *)' to 'void (*)(void *)' converts to incompatible function type [-Wcast-function-type-strict]
     187 |         ret = devm_add_action_or_reset(dev, (void (*)(void *))sysfs_put, driver_data->irq_node);
         |                                             ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/device/devres.h:181:34: note: expanded from macro 'devm_add_action_or_reset'
     181 |         __devm_add_action_or_reset(dev, action, data, #action)
         |                                         ^~~~~~
   1 warning and 2 errors generated.


vim +/readl +60 drivers/bus/altera-timeout-bridge.c

    53	
    54	static u32
    55	bridge_reg_read(struct altera_timeout_bridge_data *driver_data,
    56			u32 offset)
    57	{
    58		u32 result;
    59	
  > 60		result = readl(driver_data->bridge_registers + offset);
    61	
    62		return result;
    63	}
    64	
    65	static void bridge_reg_write(
    66		struct altera_timeout_bridge_data *driver_data,
    67		int offset, u32 value)
    68	{
  > 69		writel(value, driver_data->bridge_registers + offset);
    70	}
    71	
    72	static irqreturn_t altera_timeout_bridge_isr(int irq, void *data)
    73	{
    74		struct altera_timeout_bridge_data *driver_data = data;
    75		u32 timed_out_address;
    76		resource_size_t effective_base_address;
    77		resource_size_t effective_timed_out_address;
    78	
    79		atomic_inc(&driver_data->irq_count);
    80	
    81		// Read and print the timed-out address (encoded in the lower nibble
    82		// 0x8..0xF according to AXI Timeout Bridge IP (CSR Interrupt Status Information)
    83		timed_out_address = bridge_reg_read(
    84			driver_data,
    85			ALTERA_TIMEOUT_BRIDGE_REG_TIMED_OUT_ADDRESS);
    86		effective_base_address = driver_data->bridge_register_resource->start;
    87		effective_timed_out_address = effective_base_address + timed_out_address;
    88		pr_err("%s: timeout at address 0x%llx\n",
    89			__func__, (unsigned long long)effective_timed_out_address);
    90	
    91		// Reset IRQ status in the bridge
    92		bridge_reg_write(
    93			driver_data,
    94			ALTERA_TIMEOUT_BRIDGE_REG_IRQ_STATUS_RESET,
    95			0x1);
    96		// notify the user space
    97		sysfs_notify_dirent(driver_data->irq_node);
    98	
    99		return IRQ_HANDLED;
   100	}
   101	static int altera_timeout_bridge_probe(struct platform_device *pdev)
   102	{
   103		struct device *dev = &pdev->dev;
   104		const struct of_device_id *match;
   105		const struct of_dev_auxdata *lookup = dev_get_platdata(dev);
   106		struct device_node *np = dev->of_node;
   107		struct altera_timeout_bridge_data *driver_data;
   108		int ret = 0;
   109		int irq = -1;
   110	
   111		/*
   112		 * Allow user to use driver_override to bind this driver to a
   113		 * transparent bus device which has a different compatible string
   114		 * that's not listed in simple_pm_bus_of_match. We don't want to do any
   115		 * of the simple-pm-bus tasks for these devices, so return early.
   116		 */
   117		if (device_has_driver_override(&pdev->dev))
   118			return 0;
   119	
   120		match = of_match_device(dev->driver->of_match_table, dev);
   121	
   122		/* Use a fall back logic like in simple-pm-bus */
   123		if (match && match->data) {
   124			if (of_property_match_string(np, "compatible", match->compatible) == 0)
   125				return 0;
   126			else
   127				return -ENODEV;
   128		}
   129	
   130		driver_data =
   131			devm_kzalloc(&pdev->dev, sizeof(*driver_data), GFP_KERNEL);
   132		if (!driver_data) {
   133			dev_err(&pdev->dev,
   134				"%s: kzalloc failed: no memory for the driver's data, returning ENOMEM\n",
   135				__func__);
   136			return -ENOMEM;
   137		}
   138	
   139		driver_data->dev = dev;
   140		platform_set_drvdata(pdev, driver_data);
   141	
   142		driver_data->bridge_register_resource =
   143			platform_get_resource(pdev, IORESOURCE_MEM, 0);
   144		if (!driver_data->bridge_register_resource) {
   145			dev_err(dev,
   146				"%s: missing required reg binding\n",
   147				__func__);
   148			return -ENOENT;
   149		}
   150		driver_data->bridge_registers =
   151			devm_ioremap_resource(dev,
   152					     driver_data->bridge_register_resource);
   153		if (IS_ERR(driver_data->bridge_registers)) {
   154			dev_err(dev,
   155				"%s: ioremap_resource failed for bridge-status MMIO, returning PTR_ERR(%ld)\n",
   156				__func__, PTR_ERR(driver_data->bridge_registers));
   157			return PTR_ERR(driver_data->bridge_registers);
   158		}
   159	
   160		irq = platform_get_irq(pdev, 0);
   161		if (irq < 0) {
   162			dev_err(dev,
   163				"%s: platform_get_irq failed: %d\n", __func__, irq);
   164			return irq;
   165		}
   166	
   167		ret = devm_request_irq(dev, irq,
   168				       altera_timeout_bridge_isr,
   169				       0,
   170				       dev_name(dev),
   171				       driver_data);
   172		if (ret) {
   173			dev_err(dev,
   174				"%s: devm_request_irq failed for IRQ %d: %d\n",
   175				__func__, irq, ret);
   176			return ret;
   177		}
   178	
   179		ret = devm_device_add_group(dev, &altera_timeout_bridge_sysfs_group);
   180		if (ret)
   181			return ret;
   182	
   183		driver_data->irq_node = sysfs_get_dirent(dev->kobj.sd, "timeout_irq");
   184		if (!driver_data->irq_node)
   185			return -ENOENT;
   186	
 > 187		ret = devm_add_action_or_reset(dev, (void (*)(void *))sysfs_put, driver_data->irq_node);
   188		if (ret)
   189			return ret;
   190	
   191		if (np)
   192			of_platform_populate(np, NULL, lookup, &pdev->dev);
   193	
   194		return 0;
   195	}
   196	

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH 1/2] dt-bindings: bus: Add binding for Altera AXI Timeout Bridge

[Rob Herring (Arm)]

On Sat, 03 Oct 2026 20:19:19 +0000, Vyacheslav Yurkov wrote:
> Add a device tree binding for the Altera timeout bridge, which connects
> an Avalon bus to the HPS and provides an address space for child
> devices with a fall back to a simple bus.
> 
> Signed-off-by: Vyacheslav Yurkov <V.Yurkov.EXT@bruker.com>
> ---
>  .../bindings/bus/altera-timeout-bridge.yaml        | 82 ++++++++++++++++++++++
>  1 file changed, 82 insertions(+)
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:

dtschema/dtc warnings/errors:
Documentation/devicetree/bindings/bus/altera-timeout-bridge.example.dtb: /example-0/timeout_bridge_hps@10000/timeout-device@100: failed to match any schema with compatible: ['timeout-device']

doc reference errors (make refcheckdocs):

See https://patchwork.kernel.org/project/devicetree/patch/20261003-feature-timeout-ip-v1-1-8837c311d571@bruker.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.

Re: [PATCH 2/2] bus: add Altera timeout bridge driver

[kernel test robot]

Hi Vyacheslav,

kernel test robot noticed the following build errors:

[auto build test ERROR on a74306e2e676f9775457366fc047a660fbf02f26]

url:    https://github.com/intel-lab-lkp/linux/commits/Vyacheslav-Yurkov-via-B4-Relay/dt-bindings-bus-Add-binding-for-Altera-AXI-Timeout-Bridge/20261003-201919
base:   a74306e2e676f9775457366fc047a660fbf02f26
patch link:    https://lore.kernel.org/r/20261003-feature-timeout-ip-v1-2-8837c311d571%40bruker.com
patch subject: [PATCH 2/2] bus: add Altera timeout bridge driver
config: s390-allyesconfig (https://download.01.org/0day-ci/archive/20261006/202610061734.ZXwVnIt2-lkp@intel.com/config)
compiler: s390-linux-gcc (GCC) 16.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20261006/202610061734.ZXwVnIt2-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202610061734.ZXwVnIt2-lkp@intel.com/

All errors (new ones prefixed by >>):

   drivers/bus/altera-timeout-bridge.c: In function 'bridge_reg_read':
>> drivers/bus/altera-timeout-bridge.c:60:18: error: implicit declaration of function 'readl' [-Wimplicit-function-declaration]
      60 |         result = readl(driver_data->bridge_registers + offset);
         |                  ^~~~~
   drivers/bus/altera-timeout-bridge.c: In function 'bridge_reg_write':
>> drivers/bus/altera-timeout-bridge.c:69:9: error: implicit declaration of function 'writel' [-Wimplicit-function-declaration]
      69 |         writel(value, driver_data->bridge_registers + offset);
         |         ^~~~~~


vim +/readl +60 drivers/bus/altera-timeout-bridge.c

    53	
    54	static u32
    55	bridge_reg_read(struct altera_timeout_bridge_data *driver_data,
    56			u32 offset)
    57	{
    58		u32 result;
    59	
  > 60		result = readl(driver_data->bridge_registers + offset);
    61	
    62		return result;
    63	}
    64	
    65	static void bridge_reg_write(
    66		struct altera_timeout_bridge_data *driver_data,
    67		int offset, u32 value)
    68	{
  > 69		writel(value, driver_data->bridge_registers + offset);
    70	}
    71	

--
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