[PATCH v8 0/2] hwmon: add Altera SoC FPGA hardware monitoring support

[PATCH v8 0/2] hwmon: add Altera SoC FPGA hardware monitoring support

[tze.yee.ng]

From: Tze Yee Ng <tze.yee.ng@altera.com>

This series adds hardware monitor support for Altera SoC FPGA devices.
Temperature and voltage sensors are accessed through the Stratix 10
service layer and Secure Device Manager (SDM).

Patch 1 adds async HWMON SMC support to stratix10-svc and registers the
socfpga-hwmon platform device.

Patch 2 adds the socfpga-hwmon driver, documentation, Kconfig, and
MAINTAINERS entry.

Changes in v8:
- In Patch 2, address maintainer and Sashiko review feedback on 
  socfpga-hwmon driver:
  - Drop the extra wait_for_completion() after sync-mode timeout; on
    timeout report -ETIMEDOUT and call stratix10_svc_done().
    The previous wait could hang forever if receive_cb is never invoked
    (e.g. BUSY/REJECTED for HWMON). Any leftover svc_fifo race will be
    handled in a separate stratix10-svc series.
  - Place socfpga-hwmon alphabetically in Documentation/hwmon/index.rst
- No functional changes in Patch 1

Changes in v7:
- In Patch 2, address maintainer and Sashiko review feedback on 
  socfpga-hwmon:
  - Break out of the async poll loop on hard errors and return the real
    poll status instead of rewriting it to -ETIMEDOUT
  - Drop redundant async poll alert/debug messages (SVC already logs)
  - Replace msleep(1) with usleep_range() for short retries
  - On sync-mode timeout, wait for the outstanding SVC callback before
    calling stratix10_svc_done() so a leftover svc_fifo request cannot
    desynchronize later sensor reads; still report -ETIMEDOUT
- No functional changes in Patch 1

Changes in v6:
- Rebase on torvalds/master (given “Linux 7.2-rc4”)
- No functional changes in Patch 1 and Patch 2

Changes in v5:
- Rebase on dinguyen/socfpga_svc_fixes_for_v7.2
- Address Sashiko review feedback on socfpga-hwmon (Patch 2):
  - Poll async responses until HWMON_TIMEOUT instead of a fixed
    3-iteration retry loop (~3 ms), fixing premature timeouts on
    silicon
  - Add MODULE_ALIAS("platform:socfpga-hwmon")
- No functional changes in Patch 1

Changes in v4:
- Address maintainer and review feedback on socfpga-hwmon (Patch 2):
  - Register devm_add_action_or_reset() before
    devm_hwmon_device_register_with_info() to fix devres teardown order
  - Remove unreferenced completion and pre-poll
    wait_for_completion_io_timeout() from async reads; poll directly
    with a retry loop after async_send()
- No functional changes in Patch 1

Changes in v3:
- Address review feedback on socfpga-hwmon (Patch 2):
  - Fix 16-bit Q8.8 temperature sign extension
  - Drop unused async callback; pass NULL to stratix10_svc_async_send()
  - Document and retain pre-poll wait (RSU pattern; firmware needs time
    before async_poll())
  - Align async poll retry behaviour with RSU
  - Use uninterruptible wait_for_completion_timeout() for sync reads
  - Handle -EINVAL and -EOPNOTSUPP when falling back to sync mode
  - Defer SVC channel cleanup via devm_add_action_or_reset()
- No functional changes in Patch 1

Changes in v2:
- Drop altr,stratix10-hwmon DT binding and intel,stratix10-svc hwmon
  child property
- Drop Stratix 10 SoCDK DTS hwmon node
- Register socfpga-hwmon from stratix10-svc (RSU-style)
- Replace DT channel parsing with hardcoded Stratix 10 and Agilex tables
- Rename driver/module to socfpga-hwmon 
  (CONFIG_SENSORS_ALTERA_SOCFPGA_HWMON)
- Add Agilex channel support
- Fix SDM value conversion (Q8.8 degrees Celsius and Q16 volts to hwmon
  millidegrees/millivolts)
- Improve sync-mode error handling via last_err

Previous version:
  https://lore.kernel.org/all/cover.1784599864.git.tze.yee.ng@altera.com/

Tze Yee Ng (2):
  firmware: stratix10-svc: add async HWMON read commands and register
    socfpga-hwmon device
  hwmon: add Altera SoC FPGA hardware monitoring driver

 Documentation/hwmon/index.rst                |   1 +
 Documentation/hwmon/socfpga-hwmon.rst        |  34 ++
 MAINTAINERS                                  |   8 +
 drivers/firmware/stratix10-svc.c             |  46 +-
 drivers/hwmon/Kconfig                        |  10 +
 drivers/hwmon/Makefile                       |   1 +
 drivers/hwmon/socfpga-hwmon.c                | 579 +++++++++++++++++++
 include/linux/firmware/intel/stratix10-smc.h |  38 ++
 8 files changed, 714 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/hwmon/socfpga-hwmon.rst
 create mode 100644 drivers/hwmon/socfpga-hwmon.c

-- 
2.43.7

[PATCH v8 1/2] firmware: stratix10-svc: add async HWMON read commands and register socfpga-hwmon device

[tze.yee.ng]

From: Tze Yee Ng <tze.yee.ng@altera.com>

Add asynchronous Stratix 10 service layer support for hardware monitor
temperature and voltage read commands in stratix10_svc_async_send() and
stratix10_svc_async_prepare_response().

Register a socfpga-hwmon platform device from the service layer driver
when hardware monitor support is enabled, similar to the RSU device.

Signed-off-by: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
Signed-off-by: Tze Yee Ng <tze.yee.ng@altera.com>
---
Changes in v8:
- No functional changes from v7

Changes in v7:
- No functional changes from v6

Changes in v6:
- No functional changes from v5

Changes in v5:
- No functional changes from v4

Changes in v3:
- No functional changes from v2

Changes in v2:
- Extend patch scope beyond async SMC support: register socfpga-hwmon
  platform device from stratix10-svc when CONFIG_SENSORS_ALTERA_SOCFPGA_HWMON
  is enabled
- Follow RSU-style registration; RSU probe error handling is unchanged
- Add err_unregister_clients to unregister hwmon and RSU on populate failure
- Unregister hwmon platform device in stratix10-svc remove()
---
 drivers/firmware/stratix10-svc.c             | 46 ++++++++++++++++++--
 include/linux/firmware/intel/stratix10-smc.h | 38 ++++++++++++++++
 2 files changed, 81 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/stratix10-svc.c b/drivers/firmware/stratix10-svc.c
index c24ca5823078..fc38afed5b7f 100644
--- a/drivers/firmware/stratix10-svc.c
+++ b/drivers/firmware/stratix10-svc.c
@@ -45,6 +45,7 @@
 
 /* stratix10 service layer clients */
 #define STRATIX10_RSU				"stratix10-rsu"
+#define SOCFPGA_HWMON				"socfpga-hwmon"
 
 /* Maximum number of SDM client IDs. */
 #define MAX_SDM_CLIENT_IDS			16
@@ -104,9 +105,11 @@ struct stratix10_svc_chan;
 /**
  * struct stratix10_svc - svc private data
  * @stratix10_svc_rsu: pointer to stratix10 RSU device
+ * @stratix10_svc_hwmon: pointer to stratix10 HWMON device
  */
 struct stratix10_svc {
 	struct platform_device *stratix10_svc_rsu;
+	struct platform_device *stratix10_svc_hwmon;
 };
 
 /**
@@ -1329,6 +1332,14 @@ int stratix10_svc_async_send(struct stratix10_svc_chan *chan, void *msg,
 		args.a0 = INTEL_SIP_SMC_ASYNC_RSU_NOTIFY;
 		args.a2 = p_msg->arg[0];
 		break;
+	case COMMAND_HWMON_READTEMP:
+		args.a0 = INTEL_SIP_SMC_ASYNC_HWMON_READTEMP;
+		args.a2 = p_msg->arg[0];
+		break;
+	case COMMAND_HWMON_READVOLT:
+		args.a0 = INTEL_SIP_SMC_ASYNC_HWMON_READVOLT;
+		args.a2 = p_msg->arg[0];
+		break;
 	default:
 		dev_err(ctrl->dev, "Invalid command ,%d\n", p_msg->command);
 		ret = -EINVAL;
@@ -1422,6 +1433,10 @@ static int stratix10_svc_async_prepare_response(struct stratix10_svc_chan *chan,
 		 */
 		data->kaddr1 = (void *)&handle->res;
 		break;
+	case COMMAND_HWMON_READTEMP:
+	case COMMAND_HWMON_READVOLT:
+		data->kaddr1 = (void *)&handle->res.a2;
+		break;
 
 	default:
 		dev_alert(ctrl->dev, "Invalid command\n ,%d", p_msg->command);
@@ -2013,16 +2028,38 @@ static int stratix10_svc_drv_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_put_device;
 
+	if (IS_ENABLED(CONFIG_SENSORS_ALTERA_SOCFPGA_HWMON)) {
+		svc->stratix10_svc_hwmon =
+			platform_device_alloc(SOCFPGA_HWMON, 0);
+		if (!svc->stratix10_svc_hwmon) {
+			dev_err(dev, "failed to allocate %s device\n",
+				SOCFPGA_HWMON);
+		} else {
+			svc->stratix10_svc_hwmon->dev.parent = dev;
+
+			ret = platform_device_add(svc->stratix10_svc_hwmon);
+			if (ret) {
+				dev_err(dev, "failed to add %s device: %d\n",
+					SOCFPGA_HWMON, ret);
+				platform_device_put(svc->stratix10_svc_hwmon);
+				svc->stratix10_svc_hwmon = NULL;
+			}
+		}
+	}
+
 	ret = of_platform_default_populate(dev_of_node(dev), NULL, dev);
 	if (ret)
-		goto err_unregister_rsu_dev;
+		goto err_unregister_clients;
 
 	pr_info("Intel Service Layer Driver Initialized\n");
 
 	return 0;
 
-err_unregister_rsu_dev:
-	platform_device_unregister(svc->stratix10_svc_rsu);
+err_unregister_clients:
+	if (svc->stratix10_svc_hwmon)
+		platform_device_unregister(svc->stratix10_svc_hwmon);
+	if (svc->stratix10_svc_rsu)
+		platform_device_unregister(svc->stratix10_svc_rsu);
 	goto err_free_fifos;
 err_put_device:
 	platform_device_put(svc->stratix10_svc_rsu);
@@ -2046,6 +2083,9 @@ static void stratix10_svc_drv_remove(struct platform_device *pdev)
 	struct stratix10_svc_controller *ctrl = platform_get_drvdata(pdev);
 	struct stratix10_svc *svc = ctrl->svc;
 
+	if (svc->stratix10_svc_hwmon)
+		platform_device_unregister(svc->stratix10_svc_hwmon);
+
 	stratix10_svc_async_exit(ctrl);
 
 	of_platform_depopulate(ctrl->dev);
diff --git a/include/linux/firmware/intel/stratix10-smc.h b/include/linux/firmware/intel/stratix10-smc.h
index 9116512169dc..18ac6fe96d9d 100644
--- a/include/linux/firmware/intel/stratix10-smc.h
+++ b/include/linux/firmware/intel/stratix10-smc.h
@@ -695,6 +695,44 @@ INTEL_SIP_SMC_FAST_CALL_VAL(INTEL_SIP_SMC_FUNCID_FPGA_CONFIG_COMPLETED_WRITE)
 #define INTEL_SIP_SMC_ASYNC_POLL \
 	INTEL_SIP_SMC_ASYNC_VAL(INTEL_SIP_SMC_ASYNC_FUNC_ID_POLL)
 
+/**
+ * Request INTEL_SIP_SMC_ASYNC_HWMON_READTEMP
+ * Async call to request temperature
+ *
+ * Call register usage:
+ * a0 INTEL_SIP_SMC_ASYNC_HWMON_READTEMP
+ * a1 transaction job id
+ * a2 Temperature Channel
+ * a3-a17 not used
+ *
+ * Return status
+ * a0 INTEL_SIP_SMC_STATUS_OK, INTEL_SIP_SMC_STATUS_REJECTED
+ * or INTEL_SIP_SMC_STATUS_BUSY
+ * a1-a17 not used
+ */
+#define INTEL_SIP_SMC_ASYNC_FUNC_ID_HWMON_READTEMP	0xE8
+#define INTEL_SIP_SMC_ASYNC_HWMON_READTEMP \
+	INTEL_SIP_SMC_ASYNC_VAL(INTEL_SIP_SMC_ASYNC_FUNC_ID_HWMON_READTEMP)
+
+/**
+ * Request INTEL_SIP_SMC_ASYNC_HWMON_READVOLT
+ * Async call to request voltage
+ *
+ * Call register usage:
+ * a0 INTEL_SIP_SMC_ASYNC_HWMON_READVOLT
+ * a1 transaction job id
+ * a2 Voltage Channel
+ * a3-a17 not used
+ *
+ * Return status
+ * a0 INTEL_SIP_SMC_STATUS_OK, INTEL_SIP_SMC_STATUS_REJECTED
+ * or INTEL_SIP_SMC_STATUS_BUSY
+ * a1-a17 not used
+ */
+#define INTEL_SIP_SMC_ASYNC_FUNC_ID_HWMON_READVOLT	0xE9
+#define INTEL_SIP_SMC_ASYNC_HWMON_READVOLT \
+	INTEL_SIP_SMC_ASYNC_VAL(INTEL_SIP_SMC_ASYNC_FUNC_ID_HWMON_READVOLT)
+
 /**
  * Request INTEL_SIP_SMC_ASYNC_RSU_GET_SPT
  * Async call to get RSU SPT from SDM.
-- 
2.43.7

Re: [PATCH v8 1/2] firmware: stratix10-svc: add async HWMON read commands and register socfpga-hwmon device

[NG, TZE YEE]

On 23/7/2026 2:14 pm, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
> 
> New issues:
> - [Medium] Hardware monitoring functionality is improperly registered as a platform device instead of an auxiliary device.
> 

I'll keep the platform device registration for this series. I’m
happy to look at converting socfpga-hwmon to an auxiliary device in a
follow-up if preferred.

> Pre-existing issues:
> - [High] Pre-existing Use-After-Free race condition during module removal due to improper teardown ordering of child devices.

It is fixed in
https://lore.kernel.org/all/6630a1568f162d9455e0580f7ccadc262db4718e.1784007275.git.adrian.ho.yin.ng@altera.com/

> --
> 
> --- Patch [1]: [PATCH v8 1/2] firmware: stratix10-svc: add async HWMON read commands and register socfpga-hwmon device ---
> commit 5ba2e4fb155f074de568280aeede81883f87924e
> Author: Tze Yee Ng <tze.yee.ng@altera.com>
> 
> firmware: stratix10-svc: add async HWMON read commands and register socfpga-hwmon device
> 
> Add asynchronous Stratix 10 service layer support for hardware monitor
> temperature and voltage read commands. Register a socfpga-hwmon platform
> device from the service layer driver when hardware monitor support is enabled.
> 
>> diff --git a/drivers/firmware/stratix10-svc.c b/drivers/firmware/stratix10-svc.c
>> index c24ca5823078f..fc38afed5b7fe 100644
>> --- a/drivers/firmware/stratix10-svc.c
>> +++ b/drivers/firmware/stratix10-svc.c
> 
> [ ... ]
> 
>> @@ -2013,16 +2028,38 @@ static int stratix10_svc_drv_probe(struct platform_device *pdev)
>>   	if (ret)
>>   		goto err_put_device;
>>   
>> +	if (IS_ENABLED(CONFIG_SENSORS_ALTERA_SOCFPGA_HWMON)) {
>> +		svc->stratix10_svc_hwmon =
>> +			platform_device_alloc(SOCFPGA_HWMON, 0);
> 
> [Severity: Medium]
> According to the hardware monitoring subsystem guidelines, if the main
> functionality of a chip is not hardware monitoring, its secondary hardware
> monitoring functionality should be implemented as an auxiliary device driver.
> 
> Since the primary purpose of this module is the firmware service layer,
> does registering the hardware monitoring functionality as a platform device
> violate the subsystem API layering? Could this be implemented via the
> auxiliary bus instead of using platform_device_alloc()?
> 
>> +		if (!svc->stratix10_svc_hwmon) {
>> +			dev_err(dev, "failed to allocate %s device\n",
>> +				SOCFPGA_HWMON);
>> +		} else {
>> +			svc->stratix10_svc_hwmon->dev.parent = dev;
>> +
>> +			ret = platform_device_add(svc->stratix10_svc_hwmon);
>> +			if (ret) {
>> +				dev_err(dev, "failed to add %s device: %d\n",
>> +					SOCFPGA_HWMON, ret);
>> +				platform_device_put(svc->stratix10_svc_hwmon);
>> +				svc->stratix10_svc_hwmon = NULL;
>> +			}
>> +		}
>> +	}
>> +
>>   	ret = of_platform_default_populate(dev_of_node(dev), NULL, dev);
> 
> [ ... ]
> 
>> @@ -2046,6 +2083,9 @@ static void stratix10_svc_drv_remove(struct platform_device *pdev)
>>   	struct stratix10_svc_controller *ctrl = platform_get_drvdata(pdev);
>>   	struct stratix10_svc *svc = ctrl->svc;
>>   
>> +	if (svc->stratix10_svc_hwmon)
>> +		platform_device_unregister(svc->stratix10_svc_hwmon);
>> +
>>   	stratix10_svc_async_exit(ctrl);
>>   
>>   	of_platform_depopulate(ctrl->dev);
> 
> [Severity: High]
> This is a pre-existing issue, but does this teardown order create a
> use-after-free race condition during module removal?
> 
> The stratix10_svc_drv_remove() function calls stratix10_svc_async_exit()
> before unregistering the remaining OF child devices and the RSU child device.
> The async exit function destroys the async structures and frees the
> asynchronous channels and handlers.
> 
> If userspace concurrently accesses sysfs attributes for the child devices
> while the module unloads, could it invoke stratix10_svc_async_send()
> or stratix10_svc_async_poll() after the async channels have been freed?
> 
> For example, stratix10_svc_async_send() performs lockless reads of achan:
> 
> stratix10_svc_async_send() {
> 	...
> 	achan = chan->async_chan;
> 	ctrl = chan->ctrl;
> 	actrl = &ctrl->actrl;
> 
> 	if (!actrl->initialized) {
> 	...
> }
> 
> Would this lead to memory corruption if the structures are already deallocated?
> Should the child devices be fully unregistered before calling
> stratix10_svc_async_exit() to ensure no concurrent accesses are possible?
> 

Re: [PATCH v8 1/2] firmware: stratix10-svc: add async HWMON read commands and register socfpga-hwmon device

[Guenter Roeck]

On 7/26/26 23:42, NG, TZE YEE wrote:
> On 23/7/2026 2:14 pm, sashiko-bot@kernel.org wrote:
>> Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
>>
>> New issues:
>> - [Medium] Hardware monitoring functionality is improperly registered as a platform device instead of an auxiliary device.
>>
> 
> I'll keep the platform device registration for this series. I’m
> happy to look at converting socfpga-hwmon to an auxiliary device in a
> follow-up if preferred.
> 

Agreed. Just ignore this report for this series.

Thanks,
Guenter

Re: [PATCH v8 1/2] firmware: stratix10-svc: add async HWMON read commands and register socfpga-hwmon device

[Dinh Nguyen]

Hi Guenter,

On 7/23/26 01:02, tze.yee.ng@altera.com wrote:
> From: Tze Yee Ng <tze.yee.ng@altera.com>
> 
> Add asynchronous Stratix 10 service layer support for hardware monitor
> temperature and voltage read commands in stratix10_svc_async_send() and
> stratix10_svc_async_prepare_response().
> 
> Register a socfpga-hwmon platform device from the service layer driver
> when hardware monitor support is enabled, similar to the RSU device.
> 
> Signed-off-by: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
> Signed-off-by: Tze Yee Ng <tze.yee.ng@altera.com>
> ---
I've been taking these patches through Greg KH's char-misc tree. I'll 
wait on your feedback on patch 2 to take this patch.

Thanks,
Dinh

Re: [PATCH v8 1/2] firmware: stratix10-svc: add async HWMON read commands and register socfpga-hwmon device

[Guenter Roeck]

On 7/27/26 10:02, Dinh Nguyen wrote:
> Hi Guenter,
> 
> On 7/23/26 01:02, tze.yee.ng@altera.com wrote:
>> From: Tze Yee Ng <tze.yee.ng@altera.com>
>>
>> Add asynchronous Stratix 10 service layer support for hardware monitor
>> temperature and voltage read commands in stratix10_svc_async_send() and
>> stratix10_svc_async_prepare_response().
>>
>> Register a socfpga-hwmon platform device from the service layer driver
>> when hardware monitor support is enabled, similar to the RSU device.
>>
>> Signed-off-by: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
>> Signed-off-by: Tze Yee Ng <tze.yee.ng@altera.com>
>> ---
> I've been taking these patches through Greg KH's char-misc tree. I'll wait on your feedback on patch 2 to take this patch.
> 
If with "your" you refer to me - I can not determine if Sashiko's feedback
on the second patch is correct or not. To me it sounds like real problems,
but then I don't know the code well enough to be sure, and I don't have the
time to analyze it myself. So you won't get any feedback from me unless
someone declares that Sashiko's feedback can be ignored.

Thanks,
Guenter

[PATCH v8 2/2] hwmon: add Altera SoC FPGA hardware monitoring driver

[tze.yee.ng]

From: Tze Yee Ng <tze.yee.ng@altera.com>

Add a hardware monitor driver for Altera SoC FPGA devices using the
Stratix 10 service layer. Sensor channels are selected based on the
service layer compatible string.

Signed-off-by: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
Signed-off-by: Tze Yee Ng <tze.yee.ng@altera.com>
---
Changes in v8:
- Drop the extra wait_for_completion() after sync-mode timeout; on
  timeout report -ETIMEDOUT and call stratix10_svc_done()
- Place socfpga-hwmon alphabetically in Documentation/hwmon/index.rst

Changes in v7:
- Break out of the async poll loop on hard errors; return the real poll
  status instead of -ETIMEDOUT
- Drop redundant async poll alert and -EAGAIN debug messages
- Replace msleep(1) with usleep_range() for short retries
- On sync-mode timeout, wait for the outstanding SVC callback before
  stratix10_svc_done() to avoid leftover svc_fifo entries desynchronizing
  later reads; still report -ETIMEDOUT to userspace

Changes in v6:
- No functional changes from v5

Changes in v5:
- Poll async responses until HWMON_TIMEOUT (2 s) instead of a fixed
  3-iteration retry loop (~3 ms), fixing premature timeouts observed
  on silicon
- Add MODULE_ALIAS("platform:socfpga-hwmon")

Changes in v4:
- Register devm_add_action_or_reset() before
  devm_hwmon_device_register_with_info(); drop manual channel cleanup
  on hwmon registration failure
- Remove unreferenced async completion and pre-poll
  wait_for_completion_io_timeout(); poll directly after async_send()
  with the existing retry loop

Changes in v3:
- Fix 16-bit signed Q8.8 temperature conversion (cast through s16)
- Remove unused async callback; pass NULL to stratix10_svc_async_send()
- Keep wait_for_completion_io_timeout() before polling with comment
  explaining the service layer never invokes the callback but firmware
  needs time to complete the transaction (RSU pattern)
- Align async poll loop with RSU (retry on failure instead of aborting)
- Use wait_for_completion_timeout() for synchronous reads
- Handle -EINVAL and -EOPNOTSUPP when async client registration fails
- Defer SVC channel/async cleanup via devm_add_action_or_reset();
  drop .remove()

Changes in v2:
- Drop altr,stratix10-hwmon OF compatible and DT channel parsing
- Select channels from hardcoded tables using parent SVC compatible
  (intel,stratix10-svc or intel,agilex-svc)
- Rename driver from stratix10-hwmon to socfpga-hwmon
- Rename Kconfig symbol to CONFIG_SENSORS_ALTERA_SOCFPGA_HWMON
- Add Agilex voltage and temperature channel tables
- Convert SDM Q8.8 degrees Celsius to hwmon millidegrees
- Convert SDM Q16 volts to hwmon millivolts
- Use socfpga_hwmon as hwmon sysfs device name
- Add last_err for synchronous SVC read error propagation
- Update Documentation/hwmon and MAINTAINERS accordingly
---
 Documentation/hwmon/index.rst         |   1 +
 Documentation/hwmon/socfpga-hwmon.rst |  34 ++
 MAINTAINERS                           |   8 +
 drivers/hwmon/Kconfig                 |  10 +
 drivers/hwmon/Makefile                |   1 +
 drivers/hwmon/socfpga-hwmon.c         | 579 ++++++++++++++++++++++++++
 6 files changed, 633 insertions(+)
 create mode 100644 Documentation/hwmon/socfpga-hwmon.rst
 create mode 100644 drivers/hwmon/socfpga-hwmon.c

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 29130df44d12..dfab6fec09bb 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -251,6 +251,7 @@ Hardware Monitoring Kernel Drivers
    smsc47b397
    smsc47m192
    smsc47m1
+   socfpga-hwmon
    sparx5-temp
    spd5118
    stpddc60
diff --git a/Documentation/hwmon/socfpga-hwmon.rst b/Documentation/hwmon/socfpga-hwmon.rst
new file mode 100644
index 000000000000..e5da42556a62
--- /dev/null
+++ b/Documentation/hwmon/socfpga-hwmon.rst
@@ -0,0 +1,34 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver socfpga-hwmon
+=============================
+
+Supported chips:
+
+ * Altera Stratix 10 SoC FPGA
+ * Altera Agilex SoC FPGA
+
+Authors:
+      - Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
+      - Tze Yee Ng <tze.yee.ng@altera.com>
+
+Description
+-----------
+
+This driver supports hardware monitoring for Altera SoC
+FPGA devices through the Secure Device Manager and Stratix 10 service layer.
+
+The following sensor types are supported:
+
+  * temperature
+  * voltage
+
+Usage Notes
+-----------
+
+The stratix10-svc driver registers a socfpga-hwmon platform device when
+hardware monitor support is enabled. Sensor channels are selected in the
+driver based on the service layer compatible string:
+
+  * intel,stratix10-svc
+  * intel,agilex-svc
diff --git a/MAINTAINERS b/MAINTAINERS
index a674e36529f7..ab6cb215a02f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -965,6 +965,14 @@ L:	linux-gpio@vger.kernel.org
 S:	Maintained
 F:	drivers/gpio/gpio-altera.c
 
+ALTERA SoC FPGA HWMON DRIVER
+M:	Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
+M:	Tze Yee Ng <tze.yee.ng@altera.com>
+L:	linux-hwmon@vger.kernel.org
+S:	Maintained
+F:	Documentation/hwmon/socfpga-hwmon.rst
+F:	drivers/hwmon/socfpga-hwmon.c
+
 ALTERA TRIPLE SPEED ETHERNET DRIVER
 M:	Boon Khai Ng <boon.khai.ng@altera.com>
 L:	netdev@vger.kernel.org
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 2bfbcc033d59..8e768661fec2 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -2160,6 +2160,16 @@ config SENSORS_SMSC47M192
 	  This driver can also be built as a module. If so, the module
 	  will be called smsc47m192.
 
+config SENSORS_ALTERA_SOCFPGA_HWMON
+	tristate "Altera SoC FPGA hardware monitoring features"
+	depends on INTEL_STRATIX10_SERVICE
+	help
+	  If you say yes here you get support for the temperature and
+	  voltage sensors of Altera SoC FPGA devices.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called socfpga-hwmon.
+
 config SENSORS_SMSC47B397
 	tristate "SMSC LPC47B397-NC"
 	depends on HAS_IOPORT
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 63effc0ab8d1..aeedee80e1f0 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -221,6 +221,7 @@ obj-$(CONFIG_SENSORS_SMPRO)	+= smpro-hwmon.o
 obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
 obj-$(CONFIG_SENSORS_SMSC47M1)	+= smsc47m1.o
 obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
+obj-$(CONFIG_SENSORS_ALTERA_SOCFPGA_HWMON)	+= socfpga-hwmon.o
 obj-$(CONFIG_SENSORS_SPARX5)	+= sparx5-temp.o
 obj-$(CONFIG_SENSORS_SPD5118)	+= spd5118.o
 obj-$(CONFIG_SENSORS_STTS751)	+= stts751.o
diff --git a/drivers/hwmon/socfpga-hwmon.c b/drivers/hwmon/socfpga-hwmon.c
new file mode 100644
index 000000000000..5b43274d0aa2
--- /dev/null
+++ b/drivers/hwmon/socfpga-hwmon.c
@@ -0,0 +1,579 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Altera SoC FPGA hardware monitoring driver
+ *
+ * Copyright (c) 2026 Altera Corporation
+ *
+ * Authors:
+ *	Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
+ *	Tze Yee Ng <tze.yee.ng@altera.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/cleanup.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/firmware/intel/stratix10-svc-client.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#define HWMON_TIMEOUT			msecs_to_jiffies(SVC_HWMON_REQUEST_TIMEOUT_MS)
+#define HWMON_RETRY_SLEEP_US		1000U
+#define HWMON_ASYNC_MSG_RETRY		3U
+#define SOCFPGA_HWMON_MAXSENSORS	16
+#define SOCFPGA_HWMON_CHANNEL_MASK	GENMASK(15, 0)
+#define SOCFPGA_HWMON_PAGE_SHIFT	16
+#define SOCFPGA_HWMON_CHAN(page, channel) \
+	(((page) << SOCFPGA_HWMON_PAGE_SHIFT) | \
+	 ((channel) & SOCFPGA_HWMON_CHANNEL_MASK))
+#define SOCFPGA_HWMON_ATTR_VISIBLE	0444
+/* Temperature from SDM is signed Q8.8 degrees Celsius (8 fractional bits). */
+#define SOCFPGA_HWMON_TEMP_FRAC_BITS	8
+#define SOCFPGA_HWMON_TEMP_FRAC_DIV	BIT(SOCFPGA_HWMON_TEMP_FRAC_BITS)
+#define SOCFPGA_HWMON_TEMP_MDEG_SCALE	1000
+/* Voltage from SDM is unsigned Q16 volts (16 fractional bits). */
+#define SOCFPGA_HWMON_VOLT_FRAC_BITS	16
+#define SOCFPGA_HWMON_VOLT_FRAC_DIV	BIT(SOCFPGA_HWMON_VOLT_FRAC_BITS)
+#define SOCFPGA_HWMON_VOLT_MV_SCALE	1000
+
+#define ETEMP_INACTIVE			0x80000000U
+#define ETEMP_TOO_OLD			0x80000001U
+#define ETEMP_NOT_PRESENT		0x80000002U
+#define ETEMP_TIMEOUT			0x80000003U
+#define ETEMP_CORRUPT			0x80000004U
+#define ETEMP_BUSY			0x80000005U
+#define ETEMP_NOT_INITIALIZED		0x800000FFU
+
+struct socfpga_hwmon_channel {
+	u32 reg;
+	const char *label;
+};
+
+struct socfpga_hwmon_board_data {
+	const struct socfpga_hwmon_channel *temp;
+	unsigned int num_temp;
+	const struct socfpga_hwmon_channel *volt;
+	unsigned int num_volt;
+};
+
+struct socfpga_hwmon_priv {
+	struct stratix10_svc_chan *chan;
+	struct stratix10_svc_client client;
+	struct completion completion;
+	struct mutex lock;	/* protect SVC calls */
+	bool async;
+	int last_err;		/* sync-mode SVC result; 0 on success */
+	u32 temperature;
+	u32 voltage;
+	int temperature_channels;
+	int voltage_channels;
+	const char *temp_chan_names[SOCFPGA_HWMON_MAXSENSORS];
+	const char *volt_chan_names[SOCFPGA_HWMON_MAXSENSORS];
+	u32 temp_chan[SOCFPGA_HWMON_MAXSENSORS];
+	u32 volt_chan[SOCFPGA_HWMON_MAXSENSORS];
+};
+
+static umode_t socfpga_hwmon_is_visible(const void *dev,
+					enum hwmon_sensor_types type,
+					u32 attr, int chan)
+{
+	const struct socfpga_hwmon_priv *priv = dev;
+
+	switch (type) {
+	case hwmon_temp:
+		if (chan < priv->temperature_channels)
+			return SOCFPGA_HWMON_ATTR_VISIBLE;
+		return 0;
+	case hwmon_in:
+		if (chan < priv->voltage_channels)
+			return SOCFPGA_HWMON_ATTR_VISIBLE;
+		return 0;
+	default:
+		return 0;
+	}
+}
+
+static void socfpga_hwmon_readtemp_cb(struct stratix10_svc_client *client,
+				      struct stratix10_svc_cb_data *data)
+{
+	struct socfpga_hwmon_priv *priv = client->priv;
+
+	priv->last_err = -EIO;
+	if (data->status == BIT(SVC_STATUS_OK)) {
+		priv->last_err = 0;
+		priv->temperature = (u32)*(unsigned long *)data->kaddr1;
+	} else if (data->kaddr1) {
+		dev_err(client->dev, "%s failed with status 0x%x, value 0x%lx\n",
+			__func__, data->status,
+			*(unsigned long *)data->kaddr1);
+	} else {
+		dev_err(client->dev, "%s failed with status 0x%x\n",
+			__func__, data->status);
+	}
+
+	complete(&priv->completion);
+}
+
+static void socfpga_hwmon_readvolt_cb(struct stratix10_svc_client *client,
+				      struct stratix10_svc_cb_data *data)
+{
+	struct socfpga_hwmon_priv *priv = client->priv;
+
+	priv->last_err = -EIO;
+	if (data->status == BIT(SVC_STATUS_OK)) {
+		priv->last_err = 0;
+		priv->voltage = (u32)*(unsigned long *)data->kaddr1;
+	} else if (data->kaddr1) {
+		dev_err(client->dev, "%s failed with status 0x%x, value 0x%lx\n",
+			__func__, data->status,
+			*(unsigned long *)data->kaddr1);
+	} else {
+		dev_err(client->dev, "%s failed with status 0x%x\n",
+			__func__, data->status);
+	}
+
+	complete(&priv->completion);
+}
+
+static int socfpga_hwmon_parse_temp(long *val, u32 temperature)
+{
+	switch (temperature) {
+	case ETEMP_INACTIVE:
+	case ETEMP_NOT_PRESENT:
+	case ETEMP_CORRUPT:
+	case ETEMP_NOT_INITIALIZED:
+		return -EOPNOTSUPP;
+	case ETEMP_TIMEOUT:
+	case ETEMP_BUSY:
+	case ETEMP_TOO_OLD:
+		return -EAGAIN;
+	default:
+		/* SDM returns a 16-bit signed Q8.8 value in the low 16 bits. */
+		*val = (long)(s16)(temperature & SOCFPGA_HWMON_CHANNEL_MASK) *
+			SOCFPGA_HWMON_TEMP_MDEG_SCALE / SOCFPGA_HWMON_TEMP_FRAC_DIV;
+		return 0;
+	}
+}
+
+static int socfpga_hwmon_encode_temp_arg(u32 reg, u64 *arg)
+{
+	u32 page = (reg >> SOCFPGA_HWMON_PAGE_SHIFT) & SOCFPGA_HWMON_CHANNEL_MASK;
+	u32 channel = reg & SOCFPGA_HWMON_CHANNEL_MASK;
+
+	if (channel >= SOCFPGA_HWMON_MAXSENSORS)
+		return -EINVAL;
+
+	*arg = (1ULL << channel) | ((u64)page << SOCFPGA_HWMON_PAGE_SHIFT);
+	return 0;
+}
+
+static int socfpga_hwmon_encode_volt_arg(u32 reg, u64 *arg)
+{
+	u32 channel = reg & SOCFPGA_HWMON_CHANNEL_MASK;
+
+	if (channel >= SOCFPGA_HWMON_MAXSENSORS)
+		return -EINVAL;
+
+	*arg = 1ULL << channel;
+	return 0;
+}
+
+static int socfpga_hwmon_async_read(struct device *dev,
+				    enum hwmon_sensor_types type,
+				    struct stratix10_svc_client_msg *msg)
+{
+	struct socfpga_hwmon_priv *priv = dev_get_drvdata(dev);
+	struct stratix10_svc_cb_data data = {};
+	unsigned long deadline = jiffies + HWMON_TIMEOUT;
+	void *handle = NULL;
+	int status, index, ret;
+
+	for (index = 0; index < HWMON_ASYNC_MSG_RETRY; index++) {
+		status = stratix10_svc_async_send(priv->chan, msg, &handle,
+						  NULL, NULL);
+		if (status == 0)
+			break;
+		dev_warn(dev, "Failed to send async message: %d\n", status);
+		usleep_range(HWMON_RETRY_SLEEP_US, HWMON_RETRY_SLEEP_US * 2);
+	}
+
+	if (status && !handle) {
+		dev_err(dev, "Failed to send async message after %u retries: %d\n",
+			HWMON_ASYNC_MSG_RETRY, status);
+		return status;
+	}
+
+	ret = -ETIMEDOUT;
+	while (!time_after(jiffies, deadline)) {
+		status = stratix10_svc_async_poll(priv->chan, handle, &data);
+		if (status == -EAGAIN) {
+			/* still in progress */
+		} else if (status < 0) {
+			ret = status;
+			break;
+		} else if (status == 0) {
+			ret = 0;
+			break;
+		}
+		usleep_range(HWMON_RETRY_SLEEP_US, HWMON_RETRY_SLEEP_US * 2);
+	}
+
+	if (ret) {
+		dev_err(dev, "Failed to get async response\n");
+		goto done;
+	}
+
+	if (data.status) {
+		dev_err(dev, "%s returned 0x%x from SDM\n", __func__,
+			data.status);
+		ret = -EFAULT;
+		goto done;
+	}
+
+	if (type == hwmon_temp)
+		priv->temperature = (u32)*(unsigned long *)data.kaddr1;
+	else
+		priv->voltage = (u32)*(unsigned long *)data.kaddr1;
+
+	ret = 0;
+
+done:
+	stratix10_svc_async_done(priv->chan, handle);
+	return ret;
+}
+
+static int socfpga_hwmon_sync_read(struct device *dev,
+				   enum hwmon_sensor_types type,
+				   struct stratix10_svc_client_msg *msg)
+{
+	struct socfpga_hwmon_priv *priv = dev_get_drvdata(dev);
+	int ret;
+
+	reinit_completion(&priv->completion);
+
+	if (type == hwmon_temp)
+		priv->client.receive_cb = socfpga_hwmon_readtemp_cb;
+	else
+		priv->client.receive_cb = socfpga_hwmon_readvolt_cb;
+
+	ret = stratix10_svc_send(priv->chan, msg);
+	if (ret < 0)
+		goto status_done;
+
+	ret = wait_for_completion_timeout(&priv->completion, HWMON_TIMEOUT);
+	if (!ret) {
+		dev_err(priv->client.dev, "timeout waiting for SMC call\n");
+		ret = -ETIMEDOUT;
+		goto status_done;
+	}
+
+	ret = priv->last_err;
+
+status_done:
+	stratix10_svc_done(priv->chan);
+	return ret;
+}
+
+static int socfpga_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
+			      u32 attr, int chan, long *val)
+{
+	struct socfpga_hwmon_priv *priv = dev_get_drvdata(dev);
+	struct stratix10_svc_client_msg msg = {0};
+	int ret;
+
+	if (chan >= SOCFPGA_HWMON_MAXSENSORS)
+		return -EOPNOTSUPP;
+
+	switch (type) {
+	case hwmon_temp:
+		ret = socfpga_hwmon_encode_temp_arg(priv->temp_chan[chan],
+						    &msg.arg[0]);
+		if (ret)
+			return ret;
+		msg.command = COMMAND_HWMON_READTEMP;
+		break;
+	case hwmon_in:
+		ret = socfpga_hwmon_encode_volt_arg(priv->volt_chan[chan],
+						    &msg.arg[0]);
+		if (ret)
+			return ret;
+		msg.command = COMMAND_HWMON_READVOLT;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	guard(mutex)(&priv->lock);
+	if (priv->async)
+		ret = socfpga_hwmon_async_read(dev, type, &msg);
+	else
+		ret = socfpga_hwmon_sync_read(dev, type, &msg);
+	if (ret)
+		return ret;
+
+	if (type == hwmon_temp)
+		ret = socfpga_hwmon_parse_temp(val, priv->temperature);
+	else
+		/* SDM returns Q16 volts; convert to hwmon millivolts. */
+		*val = (long)priv->voltage * SOCFPGA_HWMON_VOLT_MV_SCALE /
+			SOCFPGA_HWMON_VOLT_FRAC_DIV;
+	return ret;
+}
+
+static int socfpga_hwmon_read_string(struct device *dev,
+				     enum hwmon_sensor_types type, u32 attr,
+				     int chan, const char **str)
+{
+	struct socfpga_hwmon_priv *priv = dev_get_drvdata(dev);
+
+	switch (type) {
+	case hwmon_in:
+		*str = priv->volt_chan_names[chan];
+		return 0;
+	case hwmon_temp:
+		*str = priv->temp_chan_names[chan];
+		return 0;
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static const struct hwmon_ops socfpga_hwmon_ops = {
+	.is_visible = socfpga_hwmon_is_visible,
+	.read = socfpga_hwmon_read,
+	.read_string = socfpga_hwmon_read_string,
+};
+
+static const struct hwmon_channel_info *socfpga_hwmon_info[] = {
+	HWMON_CHANNEL_INFO(temp,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL),
+	HWMON_CHANNEL_INFO(in,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL),
+	NULL
+};
+
+static const struct hwmon_chip_info socfpga_hwmon_chip_info = {
+	.ops = &socfpga_hwmon_ops,
+	.info = socfpga_hwmon_info,
+};
+
+static const struct socfpga_hwmon_channel s10_hwmon_volt_channels[] = {
+	{ SOCFPGA_HWMON_CHAN(0, 2), "0.8V VCC" },
+	{ SOCFPGA_HWMON_CHAN(0, 3), "1.8V VCCIO_SDM" },
+	{ SOCFPGA_HWMON_CHAN(0, 6), "0.9V VCCERAM" },
+};
+
+static const struct socfpga_hwmon_channel s10_hwmon_temp_channels[] = {
+	{ SOCFPGA_HWMON_CHAN(0, 0), "Main Die SDM" },
+};
+
+static const struct socfpga_hwmon_board_data s10_hwmon_board = {
+	.temp = s10_hwmon_temp_channels,
+	.num_temp = ARRAY_SIZE(s10_hwmon_temp_channels),
+	.volt = s10_hwmon_volt_channels,
+	.num_volt = ARRAY_SIZE(s10_hwmon_volt_channels),
+};
+
+static const struct socfpga_hwmon_channel agilex_hwmon_volt_channels[] = {
+	{ SOCFPGA_HWMON_CHAN(0, 2), "0.8V VCC" },
+	{ SOCFPGA_HWMON_CHAN(0, 3), "1.8V VCCIO_SDM" },
+	{ SOCFPGA_HWMON_CHAN(0, 4), "1.8V VCCPT" },
+	{ SOCFPGA_HWMON_CHAN(0, 5), "1.2V VCCCRCORE" },
+	{ SOCFPGA_HWMON_CHAN(0, 6), "0.9V VCCH" },
+	{ SOCFPGA_HWMON_CHAN(0, 7), "0.8V VCCL" },
+};
+
+static const struct socfpga_hwmon_channel agilex_hwmon_temp_channels[] = {
+	{ SOCFPGA_HWMON_CHAN(0, 0), "Main Die SDM" },
+	{ SOCFPGA_HWMON_CHAN(1, 0), "Main Die corner bottom left max" },
+	{ SOCFPGA_HWMON_CHAN(2, 0), "Main Die corner top left max" },
+	{ SOCFPGA_HWMON_CHAN(3, 0), "Main Die corner bottom right max" },
+	{ SOCFPGA_HWMON_CHAN(4, 0), "Main Die corner top right max" },
+};
+
+static const struct socfpga_hwmon_board_data agilex_hwmon_board = {
+	.temp = agilex_hwmon_temp_channels,
+	.num_temp = ARRAY_SIZE(agilex_hwmon_temp_channels),
+	.volt = agilex_hwmon_volt_channels,
+	.num_volt = ARRAY_SIZE(agilex_hwmon_volt_channels),
+};
+
+static const struct socfpga_hwmon_board_data *
+socfpga_hwmon_get_board(struct device *dev)
+{
+	struct device_node *np = dev->of_node;
+
+	if (!np)
+		return NULL;
+
+	if (of_device_is_compatible(np, "intel,stratix10-svc"))
+		return &s10_hwmon_board;
+	if (of_device_is_compatible(np, "intel,agilex-svc"))
+		return &agilex_hwmon_board;
+
+	return NULL;
+}
+
+static int socfpga_hwmon_init_channels(struct device *dev,
+				       const struct socfpga_hwmon_board_data *board,
+				       struct socfpga_hwmon_priv *priv)
+{
+	unsigned int i;
+
+	if (board->num_temp > SOCFPGA_HWMON_MAXSENSORS ||
+	    board->num_volt > SOCFPGA_HWMON_MAXSENSORS)
+		return -EINVAL;
+
+	for (i = 0; i < board->num_temp; i++) {
+		priv->temp_chan_names[i] = board->temp[i].label;
+		priv->temp_chan[i] = board->temp[i].reg;
+	}
+	priv->temperature_channels = board->num_temp;
+
+	for (i = 0; i < board->num_volt; i++) {
+		priv->volt_chan_names[i] = board->volt[i].label;
+		priv->volt_chan[i] = board->volt[i].reg;
+	}
+	priv->voltage_channels = board->num_volt;
+
+	return 0;
+}
+
+static void socfpga_hwmon_release_svc(void *data)
+{
+	struct socfpga_hwmon_priv *priv = data;
+
+	if (priv->async)
+		stratix10_svc_remove_async_client(priv->chan);
+	stratix10_svc_free_channel(priv->chan);
+}
+
+static int socfpga_hwmon_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device *parent = dev->parent;
+	const struct socfpga_hwmon_board_data *board;
+	struct socfpga_hwmon_priv *priv;
+	struct device *hwmon_dev;
+	int ret;
+
+	if (!parent || !parent->of_node) {
+		dev_err(dev, "missing parent device node\n");
+		return -ENODEV;
+	}
+
+	board = socfpga_hwmon_get_board(parent);
+	if (!board) {
+		dev_err(dev, "unsupported service layer compatible\n");
+		return -ENODEV;
+	}
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->client.dev = dev;
+	priv->client.priv = priv;
+	init_completion(&priv->completion);
+	mutex_init(&priv->lock);
+
+	ret = socfpga_hwmon_init_channels(dev, board, priv);
+	if (ret)
+		return ret;
+
+	priv->chan = stratix10_svc_request_channel_byname(&priv->client,
+							  SVC_CLIENT_HWMON);
+	if (IS_ERR(priv->chan)) {
+		ret = PTR_ERR(priv->chan);
+		if (ret == -EPROBE_DEFER)
+			dev_dbg(dev, "service channel %s not ready, deferring probe\n",
+				SVC_CLIENT_HWMON);
+		else
+			dev_err(dev, "couldn't get service channel %s: %d\n",
+				SVC_CLIENT_HWMON, ret);
+		return ret;
+	}
+
+	ret = stratix10_svc_add_async_client(priv->chan, false);
+	switch (ret) {
+	case 0:
+		priv->async = true;
+		break;
+	case -EINVAL:
+	case -EOPNOTSUPP:
+		/*
+		 * stratix10_svc_add_async_client() returns -EINVAL when the
+		 * async controller is not initialized; fall back to sync mode.
+		 */
+		dev_dbg(dev, "async operations not supported, using sync mode\n");
+		priv->async = false;
+		break;
+	default:
+		dev_err(dev, "failed to add async client: %d\n", ret);
+		stratix10_svc_free_channel(priv->chan);
+		return ret;
+	}
+
+	ret = devm_add_action_or_reset(dev, socfpga_hwmon_release_svc, priv);
+	if (ret)
+		return ret;
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, "socfpga_hwmon",
+							 priv,
+							 &socfpga_hwmon_chip_info,
+							 NULL);
+	if (IS_ERR(hwmon_dev))
+		return PTR_ERR(hwmon_dev);
+
+	platform_set_drvdata(pdev, priv);
+	return 0;
+}
+
+static struct platform_driver socfpga_hwmon_driver = {
+	.probe = socfpga_hwmon_probe,
+	.driver = {
+		.name = "socfpga-hwmon",
+	},
+};
+module_platform_driver(socfpga_hwmon_driver);
+
+MODULE_AUTHOR("Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>");
+MODULE_AUTHOR("Tze Yee Ng <tze.yee.ng@altera.com>");
+MODULE_DESCRIPTION("Altera SoC FPGA hardware monitoring driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:socfpga-hwmon");
-- 
2.43.7

Re: [PATCH v8 2/2] hwmon: add Altera SoC FPGA hardware monitoring driver

[NG, TZE YEE]

On 23/7/2026 2:15 pm, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [High] Timeouts in both synchronous and asynchronous read paths abandon pending requests without flushing queues or canceling them, causing permanent data desynchronization or hangs for subsequent reads.
> -->
> --- Patch [2]: [PATCH v8 2/2] hwmon: add Altera SoC FPGA hardware monitoring driver ---
> commit 467543c9f9e3893d8c84995c5e7bc8bab31dfb20
> Author: Tze Yee Ng <tze.yee.ng@altera.com>
> 
> hwmon: add Altera SoC FPGA hardware monitoring driver
> 
> This commit adds a hardware monitoring driver for Altera SoC FPGA devices
> using the Stratix 10 service layer. It supports temperature and voltage
> sensors based on the service layer compatible string.
> 
>> diff --git a/drivers/hwmon/socfpga-hwmon.c b/drivers/hwmon/socfpga-hwmon.c
>> new file mode 100644
>> --- /dev/null
>> +++ b/drivers/hwmon/socfpga-hwmon.c
> [ ... ]
>> +static int socfpga_hwmon_async_read(struct device *dev,
>> +				    enum hwmon_sensor_types type,
>> +				    struct stratix10_svc_client_msg *msg)
>> +{
> [ ... ]
>> +	ret = -ETIMEDOUT;
>> +	while (!time_after(jiffies, deadline)) {
>> +		status = stratix10_svc_async_poll(priv->chan, handle, &data);
>> +		if (status == -EAGAIN) {
>> +			/* still in progress */
>> +		} else if (status < 0) {
>> +			ret = status;
>> +			break;
>> +		} else if (status == 0) {
>> +			ret = 0;
>> +			break;
>> +		}
>> +		usleep_range(HWMON_RETRY_SLEEP_US, HWMON_RETRY_SLEEP_US * 2);
>> +	}
>> +
>> +	if (ret) {
>> +		dev_err(dev, "Failed to get async response\n");
>> +		goto done;
>> +	}
> [ ... ]
>> +done:
>> +	stratix10_svc_async_done(priv->chan, handle);
>> +	return ret;
>> +}
> 
> [Severity: High]
> If the polling loop times out, this calls stratix10_svc_async_done() which
> immediately frees the job ID via ida_free().
> 
> Since the firmware might still be processing this request, could the next
> async read reuse this job ID and intercept the delayed completion of this
> timed-out request?
> 

Agreed — this is a valid concern.

On async timeout we call stratix10_svc_async_done(), which frees the
job ID via ida_free(). Poll is keyed by transaction_id, so if firmware
is still completing the old request, a later async_send() that reuses
that job ID could observe the delayed response.

A proper fix belongs in the SVC / ATF (e.g. cancel before
freeing the ID, or keep the ID allocated until firmware completion).
We will address that in a separate SVC series rather than papering over
it in the hwmon driver.

Please let me know if you would prefer a different approach.

> [ ... ]
>> +static int socfpga_hwmon_sync_read(struct device *dev,
>> +				   enum hwmon_sensor_types type,
>> +				   struct stratix10_svc_client_msg *msg)
>> +{
> [ ... ]
>> +	ret = wait_for_completion_timeout(&priv->completion, HWMON_TIMEOUT);
>> +	if (!ret) {
>> +		dev_err(priv->client.dev, "timeout waiting for SMC call\n");
>> +		ret = -ETIMEDOUT;
>> +		goto status_done;
>> +	}
>> +
>> +	ret = priv->last_err;
>> +
>> +status_done:
>> +	stratix10_svc_done(priv->chan);
>> +	return ret;
>> +}
> 
> [Severity: High]
> If wait_for_completion_timeout() times out, this calls stratix10_svc_done(),
> which stops the worker thread via kthread_stop() without flushing the pending
> message from the channel's svc_fifo.
> 
> If the worker thread evaluates kthread_should_stop() before dequeuing the
> message, will the stale message stay in the queue?
> 
> If so, could the next read spawn a new thread that dequeues the stale message
> and returns wrong data (like returning a voltage reading for a temperature
> request)?
> 
> Also, if the worker thread is stuck inside the SMC call, won't kthread_stop()
> block indefinitely, hanging the reader process?
> 

v8 drops the extra wait_for_completion() after timeout, then it reports 
-ETIMEDOUT and calls stratix10_svc_done(). As noted in my earlier reply 
to Guenter [1], the remaining concern is that stratix10_svc_done() stops 
the worker without flushing svc_fifo, so a request dequeued only after 
the client has already timed out could theoretically desynchronize a 
later read. We plan to address that with a FIFO flush in the service 
layer in a separate series.

[1] 
https://lore.kernel.org/all/fc7b576c-6e83-45c9-aeb4-49f02113fdd0@altera.com/

Thanks,
Tze Yee