hwmon: add Altera SoC FPGA hardware monitoring support

From: Tze Yee Ng <[email protected]>

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/[email protected]/

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

From: Tze Yee Ng <[email protected]>

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.

---
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(-)

index c24ca5823078..fc38afed5b7f 100644
@@ -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);

index 9116512169dc..18ac6fe96d9d 100644
@@ -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

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.

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

Agreed. Just ignore this report for this series.

Thanks,
Guenter

Hi Guenter,

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

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

From: Tze Yee Ng <[email protected]>

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.

---
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

index 29130df44d12..dfab6fec09bb 100644
@@ -251,6 +251,7 @@ Hardware Monitoring Kernel Drivers
    smsc47b397
    smsc47m192
    smsc47m1
+   socfpga-hwmon
    sparx5-temp
    spd5118
    stpddc60

new file mode 100644
index 000000000000..e5da42556a62
@@ -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 <[email protected]>
+      - Tze Yee Ng <[email protected]>
+
+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

index a674e36529f7..ab6cb215a02f 100644
@@ -965,6 +965,14 @@ L:	[email protected]
 S:	Maintained
 F:	drivers/gpio/gpio-altera.c
 
+ALTERA SoC FPGA HWMON DRIVER
+M:	Nazim Amirul <[email protected]>
+M:	Tze Yee Ng <[email protected]>
+L:	[email protected]
+S:	Maintained
+F:	Documentation/hwmon/socfpga-hwmon.rst
+F:	drivers/hwmon/socfpga-hwmon.c
+
 ALTERA TRIPLE SPEED ETHERNET DRIVER
 M:	Boon Khai Ng <[email protected]>
 L:	[email protected]

index 2bfbcc033d59..8e768661fec2 100644
@@ -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

index 63effc0ab8d1..aeedee80e1f0 100644
@@ -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

2.43.7

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.

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/[email protected]/

Thanks,
Tze Yee

I assume that the series will be applied through some other maintainer tree.

Guenter

I can take this series.

Thanks,
Dinh