Alert_l: Modify APML ALERT_L to remove the dependency of RMI/TSI dts device node. #202

sathyapk · 2025-11-20T06:04:05Z

The PR has AMD APML Alert_L driver architecture by replacing static device tree-based device discovery with a dynamic, centralized device registration system. This enhancement improves maintainability, reduces DTS complexity, and enables flexible multi-socket configurations.

Key changes:

Add centralized device registration system for AMD APML devices. Provides global
device list where SBRMI and SBTSI drivers can register themselves, enabling the Alert_L driver
to discover and safely process alerts from registered devices.
Remove explicit sbrmi and sbtsi device references from Alert_L device tree nodes.
Add device registration/unregistration calls to SBTSI/SBRMI drivers during probe/remove.

Existing implementation #143 - Reviewed and tested:
a70993b dt-bindings: misc: apml-alertl: Add APML Alert_L bindings
dc5a9b9 arm64: dts: aspeed: Alert_L changes for Kenya & Nigeria
cd8ab36 arm64: dts: aspeed: Alert_L changes for Morocco & Congo
d46dd8b misc: amd-apml: Add support for AMD APML Alert_L platform driver
7e25856 misc: amd-apml: Create common header for sbtsi device

New dynamic discovery design changes:

a3cab62 misc: amd-apml: Update Alert_L driver to use global device registry
5edd96b misc: amd-apml: Integrate SBRMI with common device registration framework
05e6627 misc: amd-apml: Integrate SBTSI with common device registration framework
a9bb359 misc: amd-apml: Add common device registration framework
cbbea02 arm64: dts: aspeed: Update alert_l node for Nigeria and Kenya
0a39fca arm64: dts: aspeed: Update alert_l node for Morocco & Congo

Attaching test report from QA: Tested on 1P and 2P sytsems
Alertl_Test_Report.xlsx

Move out the sbtsi device structure to a common header file and add device matching helper function for I2C and I3C buses. This is required to add support for the APML Alert_L module which needs access to sbtsi device struct and device matching capability. Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com> Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>

Processors from AMD provide APML ALERT_L for BMC users to monitor events. APML Alert_L is asserted in multiple events, - Machine Check Exception occurs within the system - The processor alerts the SBI on system fatal error event - Set by hardware as a result of a 0x71/0x72/0x73 command completion - Set by firmware to indicate the completion of a mailbox operation - High/Low Temperature Alert APML Alert_L module define uevents to notify registered userspace processes of the alert event. Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com> Signed-off-by: Akshay Gupta <akshay.gupta@amd.com> Signed-off-by: sathya priya kumar <SathyaPriya.K@amd.com>

-Add alertl node for P1 and P2 host processor in Morocco platform. -Add alertl node for P1 host processor in Congo platform. Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com> Signed-off-by: Akshay Gupta <akshay.gupta@amd.com> Signed-off-by: sathya priya kumar <SathyaPriya.K@amd.com>

-Add alertl node for P1 and P2 host processor in Nigeria platform. -Add alertl node for P1 host processor in Kenya platform. Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com> Signed-off-by: Akshay Gupta <akshay.gupta@amd.com> Signed-off-by: sathya priya kumar <SathyaPriya.K@amd.com>

-Document device-tree bindings for APML Alert_L driver. Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com> Signed-off-by: Akshay Gupta <akshay.gupta@amd.com> Signed-off-by: sathya priya kumar <SathyaPriya.K@amd.com> (cherry picked from commit 0f54429)

nchatrad

reviewed offline,
this changeset avoids the need for dts in alert_l module. makes it more scalable for multihost type setups aswell

drivers/misc/amd-apml/Makefile

drivers/misc/amd-apml/sbrmi.c

drivers/misc/amd-apml/apml_common.h

Remove explicit sbrmi and sbtsi device references from Alert_L device tree nodes. The updated Alert_L driver now uses dynamic device discovery through the global APML device registry instead of DTS-based device parsing. Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com> Signed-off-by: sathya priya kumar <SathyaPriya.K@amd.com> Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>

Add centralized device registration system for AMD APML devices. Provides global device list where SBRMI and SBTSI drivers can register themselves, enabling the Alert_L driver to discover and safely process alerts from registered devices. Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com> Signed-off-by: sathya priya kumar <SathyaPriya.K@amd.com> Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>

…work Add device registration/unregistration calls to SBTSI drivers. This enables Alert_L driver to discover and safely access registered TSI devices for processing temperature alerts. Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com> Signed-off-by: sathya priya kumar <SathyaPriya.K@amd.com> Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>

…work Add device registration/unregistration calls to SBRMI drivers. This enables Alert_L driver to discover and safely access registered RMI devices for processing RAS event. Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com> Signed-off-by: sathya priya kumar <SathyaPriya.K@amd.com> Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>

Modify device tree-based device discovery in Alert_L driver with centralized device registry from apml_common module. This provides more reliable to sbrmi/sbtsi device access for processing alerts and eliminates DTS parsing. Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com> Signed-off-by: Akshay Gupta <akshay.gupta@amd.com> Signed-off-by: sathya priya kumar <SathyaPriya.K@amd.com>

-Document device-tree changes for APML Alert_L driver. Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com> Signed-off-by: Akshay Gupta <akshay.gupta@amd.com> Signed-off-by: sathya priya kumar <SathyaPriya.K@amd.com>

mahkurap · 2025-12-03T12:13:54Z

Documentation/devicetree/bindings/misc/amd,apml-alertl.yaml

        gpios = <&ltpi0_gpio 20 GPIO_ACTIVE_LOW>;
-        sbrmi = <&sbrmi_p0_iod0>;
-        sbtsi = <&sbtsi_p0_iod0>;
+        socket-num =  /bits/ 8 <1>;


In the earlier change there is a mention about sbtsi device on the socket 0. A generic question, if this alert_l line is used for communication with the SBTSI as well, I think this should be mentioned in the description along with SBRMI.

mahkurap · 2025-12-03T12:28:15Z

drivers/misc/amd-apml/apml_alertl.c

-
-	dev_dbg(dev, "Sending uevent: Sock:0x%x Src:0x%x\n",
-		soc_die_num, alert_src);
+	dev_info(dev, "Sending uevent: addr:0x%x Src:0x%08x\n bus:%d pid: 0x%llx\n",


change this to dev_dbg() so that the user can enable the logging at runtime if needed for debug purposes. Otherwise for every uevent log might overwhelm the journalctl.

mahkurap · 2025-12-03T12:38:13Z

drivers/misc/amd-apml/apml_alertl.c

-
 /* Send a uevent to userspace for an APML alert */
-static int send_uevent(u8 static_address, u32 alert_src, struct device *dev)
+static int send_uevent(u8 address, u8 bus_num, u32 alert_src,


how about adding a comment on what is alert_src, and how it is different from address? Is the alret_src the gpio number? Should the user space application need to know about it? All the user space application should know about is the PID, and the socket number. I dont think the user space application need to know about the bus_num also. I dont want to question the requirements at this point, late in the game.

mahkurap · 2025-12-03T13:04:16Z

drivers/misc/amd-apml/apml_alertl.c

+	int ret;

-	dev = oob_adata->dev;
+	mutex_lock(&apml_devices_lock);


add a comment which describes the reason to have a top level mutex for all the APML devices, and an individual lock for RMI and TSI.

mahkurap · 2025-12-03T13:04:32Z

drivers/misc/amd-apml/apml_alertl.c

-	dev = oob_adata->dev;
+	mutex_lock(&apml_devices_lock);
+	list_for_each_entry(device_node, &apml_devices, list) {
+	/* Get a safe reference to the device node */


nit: indentation

mahkurap · 2025-12-03T13:07:16Z

drivers/misc/amd-apml/apml_alertl.h

-/* APML_ALERTL Sends uevent to userspace for temparature
+/* APML_ALERTL Sends uevent to userspace for temperature
 * alert and  RAS (fatal and non-fatal) error, including
 * environmental data such as socket/die and alertl source


the uevent does not contain the socket/die numbers. do we need correct the comment here?

akky16 and others added 5 commits November 20, 2025 08:57

sathyapk self-assigned this Nov 20, 2025

sathyapk requested review from mahkurap, nchatrad, srgovard and supven01 November 20, 2025 06:17

sathyapk force-pushed the alertl-nodts branch from a3cab62 to c89beef Compare November 20, 2025 07:15

nchatrad approved these changes Nov 20, 2025

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mahkurap reviewed Nov 26, 2025

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mahkurap reviewed Nov 26, 2025

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sathyapk added 5 commits November 26, 2025 18:48

sathyapk force-pushed the alertl-nodts branch 2 times, most recently from 954ada6 to 73f75f1 Compare November 26, 2025 13:23

sathyapk added 2 commits November 26, 2025 18:56

sathyapk force-pushed the alertl-nodts branch from 73f75f1 to 42893c3 Compare November 26, 2025 13:27

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Alert_l: Modify APML ALERT_L to remove the dependency of RMI/TSI dts device node. #202

Alert_l: Modify APML ALERT_L to remove the dependency of RMI/TSI dts device node. #202

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Alert_l: Modify APML ALERT_L to remove the dependency of RMI/TSI dts device node. #202

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