Message-Id: <20251216064926.15817-4-muhammadamirulasyraf.mohamadjamian@altera.com>
Date: Mon, 15 Dec 2025 22:49:24 -0800
From: muhammadamirulasyraf.mohamadjamian@...era.com
To: Guenter Roeck <linux@...ck-us.net>,
	linux-hwmon@...r.kernel.org,
	Dinh Nguyen <dinguyen@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Ang Tien Sung <tien.sung.ang@...era.com>,
	Khairul Anuar Romli <khairul.anuar.romli@...era.com>
Subject: [PATCH v1 3/5] hwmon: (altr-hwmon): Add initial support for SoCFPGA

From: Muhammad Amirul Asyraf Mohamad Jamian <muhammad.amirul.asyraf.mohamad.jamian@...era.com>

This patch introduces a new hardware monitoring (hwmon) driver for the
Altera SoCFPGA platform, enabling kernel support for monitoring voltage and
temperature sensors critical for device health and system stability.

Changes include:
- New driver implementation 'drivers/hwmon/altera-hwmon.c' providing sensor
  reading and event handling capabilities tailored for SoCFPGA hardware.

- Build system integration by adding Kconfig and Makefile entries, allowing
  users to enable the driver in kernel configuration.

- Documentation added in 'Documentation/hwmon/altera-hwmon.rst', detailing
  driver features, usage instructions, device tree bindings, and
  configuration options.

- Update to 'Documentation/hwmon/index.rst' to reference the new driver
  documentation, improving discoverability and user guidance.

Signed-off-by: Khairul Anuar Romli <khairul.anuar.romli@...era.com>
Signed-off-by: Muhammad Amirul Asyraf Mohamad Jamian <muhammad.amirul.asyraf.mohamad.jamian@...era.com>
---
 Documentation/hwmon/altr-hwmon.rst |  32 +++
 Documentation/hwmon/index.rst      |   1 +
 MAINTAINERS                        |   2 +
 drivers/hwmon/Kconfig              |  10 +
 drivers/hwmon/Makefile             |   1 +
 drivers/hwmon/altr-hwmon.c         | 427 +++++++++++++++++++++++++++++
 6 files changed, 473 insertions(+)
 create mode 100644 Documentation/hwmon/altr-hwmon.rst
 create mode 100644 drivers/hwmon/altr-hwmon.c

diff --git a/Documentation/hwmon/altr-hwmon.rst b/Documentation/hwmon/altr-hwmon.rst
new file mode 100644
index 000000000000..3ef1ca0d1686
--- /dev/null
+++ b/Documentation/hwmon/altr-hwmon.rst
@@ -0,0 +1,32 @@
+.. SPDX-License-Identifier: GPL-2.0
+Kernel driver altr-hwmon
+=========================
+
+Supported chips:
+
+ * Intel N5X
+ * Stratix10
+ * Agilex
+ * Agilex5
+
+Contributor: Kris Chaplin <kris.chaplin@...el.com>
+             Khairul Anuar Romli <khairul.anuar.romli@...era.com>
+             Muhammad Amirul Asyraf Mohamad Jamian <muhammad.amirul.asyraf.mohamad.jamian@...era.com>
+
+Description
+-----------
+
+This driver supports hardware monitoring for 64-Bit SoC FPGA and eASIC devices
+based around the Secure Device Manager and Stratix 10 Service layer.
+
+The following sensor types are supported
+
+  * temperature
+  * voltage
+
+
+Usage Notes
+-----------
+
+The driver relies on a device tree node to enumerate support present on the
+specific device. See Documentation/devicetree/bindings/hwmon/altr,socfpga-hwmon.yaml for details of the device-tree node.
diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 85d7a686883e..d37d4cbbe8b5 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -40,6 +40,7 @@ Hardware Monitoring Kernel Drivers
    adt7470
    adt7475
    aht10
+   altr-hwmon
    amc6821
    aquacomputer_d5next
    asb100
diff --git a/MAINTAINERS b/MAINTAINERS
index 8ac7fef4563a..01f776fdbf6f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -942,6 +942,8 @@ M:	Muhammad Amirul Asyraf Mohamad Jamian <muhammad.amirul.asyraf.mohamad.jamian@
 L:	linux-hwmon@...r.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/hwmon/altr,socfpga-hwmon.yaml
+F:	Documentation/hwmon/altr-hwmon.rst
+F:	drivers/hwmon/altr-hwmon.c
 
 ALTERA MAILBOX DRIVER
 M:	Tien Sung Ang <tiensung.ang@...era.com>
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index d9bac1e3057b..4351725831d3 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -2122,6 +2122,16 @@ config SENSORS_SMSC47M192
 	  This driver can also be built as a module. If so, the module
 	  will be called smsc47m192.
 
+config SENSORS_ALTERA_SOCFPGA
+	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 altera-hwmon
+
 config SENSORS_SMSC47B397
 	tristate "SMSC LPC47B397-NC"
 	depends on HAS_IOPORT
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index eade8e3b1bde..4ae4726bd0cb 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -218,6 +218,7 @@ 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-$(CONFIG_SENSORS_ALTERA_SOCFPGA)	+= altr-hwmon.o
 obj-$(CONFIG_SENSORS_SPARX5)	+= sparx5-temp.o
 obj-$(CONFIG_SENSORS_SPD5118)	+= spd5118.o
 obj-$(CONFIG_SENSORS_STTS751)	+= stts751.o
diff --git a/drivers/hwmon/altr-hwmon.c b/drivers/hwmon/altr-hwmon.c
new file mode 100644
index 000000000000..beecfa8537a4
--- /dev/null
+++ b/drivers/hwmon/altr-hwmon.c
@@ -0,0 +1,427 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Altera SoC FPGA hardware monitoring driver
+ *
+ * Copyright (c) 2021 Intel Corporation. All rights reserved
+ * Copyright (c) 2025 Altera Corporation. All rights reserved
+ *
+ * Contributors:
+ *	Kris Chaplin <kris.chaplin@...el.com>
+ *	Ang Tien Sung <tiensung.ang@...era.com>
+ *	Adrian Ng Ho Yin <adrianhoyin.ng@...era.com>
+ *	Khairul Anuar Romli <khairul.anuar.romli@...era.com>
+ *	Muhammad Amirul Asyraf Mohamad Jamian <muhammad.amirul.asyraf.mohamad.jamian@...era.com>
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/module.h>
+#include <linux/firmware/intel/stratix10-svc-client.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+
+#define HWMON_TIMEOUT     (msecs_to_jiffies(SVC_HWMON_REQUEST_TIMEOUT_MS))
+
+#define ETEMP_INACTIVE         0x80000000
+#define ETEMP_TOO_OLD          0x80000001
+#define ETEMP_NOT_PRESENT      0x80000002
+#define ETEMP_TIMEOUT          0x80000003
+#define ETEMP_CORRUPT          0x80000004
+#define ETEMP_BUSY             0x80000005
+#define ETEMP_NOT_INITIALIZED  0x800000FF
+
+#define ALTR_SOCFPGA_HWMON_MAXSENSORS 16
+#define ALTR_SOCFPGA_HWMON_TEMPERATURE "temperature"
+#define ALTR_SOCFPGA_HWMON_VOLTAGE "voltage"
+
+struct altr_socfpga_hwmon_priv {
+	struct stratix10_svc_chan *chan;
+	struct stratix10_svc_client client;
+	struct completion completion;
+	struct mutex lock; /* protect fpga mailbox access */
+	int temperature;
+	int voltage;
+	int temperature_channels;
+	int voltage_channels;
+	const char *altr_socfpga_volt_chan_names[ALTR_SOCFPGA_HWMON_MAXSENSORS];
+	const char *altr_socfpga_temp_chan_names[ALTR_SOCFPGA_HWMON_MAXSENSORS];
+	u32 altr_socfpga_volt_chan[ALTR_SOCFPGA_HWMON_MAXSENSORS];
+	u32 altr_socfpga_temp_chan[ALTR_SOCFPGA_HWMON_MAXSENSORS];
+};
+
+static umode_t altr_socfpga_is_visible(const void *dev,
+				       enum hwmon_sensor_types type,
+				       u32 attr, int chan)
+{
+	const struct altr_socfpga_hwmon_priv *priv = dev;
+
+	switch (type) {
+	case hwmon_temp:
+		if (chan < priv->temperature_channels)
+			return 0444;
+
+		return 0;
+	case hwmon_in:
+		if (chan < priv->voltage_channels)
+			return 0444;
+
+		return 0;
+
+	default:
+		return 0;
+	}
+}
+
+static void altr_socfpga_readtemp_smc_callback(struct stratix10_svc_client *client,
+					       struct stratix10_svc_cb_data *data)
+{
+	struct altr_socfpga_hwmon_priv *priv = client->priv;
+	struct arm_smccc_res *res = (struct arm_smccc_res *)data->kaddr1;
+
+	if (data->status == BIT(SVC_STATUS_OK)) {
+		priv->temperature = res->a0;
+	} else {
+		dev_err(client->dev, "%s returned 0x%lX\n",
+			__func__, res->a0);
+	}
+
+	complete(&priv->completion);
+}
+
+static void altr_socfpga_readvolt_smc_callback(struct stratix10_svc_client *client,
+					       struct stratix10_svc_cb_data *data)
+{
+	struct altr_socfpga_hwmon_priv *priv = client->priv;
+	struct arm_smccc_res *res = (struct arm_smccc_res *)data->kaddr1;
+
+	if (data->status == BIT(SVC_STATUS_OK)) {
+		priv->voltage = res->a0;
+	} else {
+		dev_err(client->dev, "%s returned 0x%lX\n",
+			__func__, res->a0);
+	}
+
+	complete(&priv->completion);
+}
+
+static int altr_socfpga_read(struct device *dev, enum hwmon_sensor_types type,
+			     u32 attr, int chan, long *val)
+{
+	struct altr_socfpga_hwmon_priv *priv = dev_get_drvdata(dev);
+	struct stratix10_svc_client_msg msg;
+	int ret;
+
+	mutex_lock(&priv->lock);
+
+	reinit_completion(&priv->completion);
+
+	switch (type) {
+	case hwmon_temp:
+		if (chan > 15)
+			return -EOPNOTSUPP;
+
+		/* To support Page at upper word and channel at lower word */
+		msg.arg[0] = (((u64)1 << (priv->altr_socfpga_temp_chan[chan] & 0xFFFF))
+				+ (priv->altr_socfpga_temp_chan[chan] & 0xFFF0000));
+		priv->client.receive_cb = altr_socfpga_readtemp_smc_callback;
+		msg.command = COMMAND_HWMON_READTEMP;
+
+		ret = stratix10_svc_send(priv->chan, &msg);
+		if (ret < 0)
+			goto status_done;
+
+		ret = wait_for_completion_interruptible_timeout(&priv->completion,
+								HWMON_TIMEOUT);
+
+		if (!ret) {
+			dev_err(priv->client.dev,
+				"timeout waiting for SMC call\n");
+			ret = -ETIMEDOUT;
+			goto status_done;
+		} else if (ret < 0) {
+			dev_err(priv->client.dev,
+				"error %d waiting for SMC call\n", ret);
+			goto status_done;
+		} else {
+			ret = 0;
+		}
+
+		*val = ((long)(priv->temperature)) * 1000 /  256;
+
+		switch (priv->temperature) {
+		case ETEMP_INACTIVE:
+		case ETEMP_NOT_PRESENT:
+		case ETEMP_CORRUPT:
+		case ETEMP_NOT_INITIALIZED:
+			ret = -EOPNOTSUPP;
+			break;
+
+		case ETEMP_TIMEOUT:
+		case ETEMP_BUSY:
+		case ETEMP_TOO_OLD:
+			ret = -EAGAIN;
+			break;
+		default:
+			ret = 0;
+			break;
+		}
+
+		break;
+
+	case hwmon_in: // Read voltage
+		if (chan > 15)
+			return -EOPNOTSUPP; // Channel outside of range
+
+		msg.arg[0] = ((u64)1 << priv->altr_socfpga_volt_chan[chan]);
+		priv->client.receive_cb = altr_socfpga_readvolt_smc_callback;
+		msg.command = COMMAND_HWMON_READVOLT;
+
+		ret = stratix10_svc_send(priv->chan, &msg);
+		if (ret < 0)
+			goto status_done;
+
+		ret = wait_for_completion_interruptible_timeout(&priv->completion,
+								HWMON_TIMEOUT);
+
+		if (!ret) {
+			dev_err(priv->client.dev,
+				"timeout waiting for SMC call\n");
+			ret = -ETIMEDOUT;
+			goto status_done;
+		}  else if (ret < 0) {
+			dev_err(priv->client.dev,
+				"error %d waiting for SMC call\n", ret);
+			goto status_done;
+		} else {
+			ret = 0;
+		}
+
+		*val = ((long)(priv->voltage)) * 1000 /  65536;
+		ret = 0;
+		break;
+
+	default:
+		ret = -EOPNOTSUPP;
+		break;
+	}
+
+status_done:
+	stratix10_svc_done(priv->chan);
+	mutex_unlock(&priv->lock);
+	return ret;
+}
+
+static int altr_socfpga_read_string(struct device *dev,
+				    enum hwmon_sensor_types type, u32 attr,
+				    int chan, const char **str)
+{
+	struct altr_socfpga_hwmon_priv *priv = dev_get_drvdata(dev);
+
+	switch (type) {
+	case hwmon_in:
+		*str = priv->altr_socfpga_volt_chan_names[chan];
+		return 0;
+	case hwmon_temp:
+		*str = priv->altr_socfpga_temp_chan_names[chan];
+		return 0;
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static const struct hwmon_ops altr_socfpga_hwmon_ops = {
+	.is_visible = altr_socfpga_is_visible,
+	.read = altr_socfpga_read,
+	.read_string = altr_socfpga_read_string,
+};
+
+static const struct hwmon_channel_info *altr_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 altr_socfpga_hwmon_chip_info = {
+	.ops = &altr_socfpga_hwmon_ops,
+	.info = altr_socfpga_hwmon_info,
+};
+
+static int altr_socfpga_add_channel(struct device *dev,  const char *type,
+				    u32 val, const char *label,
+				    struct altr_socfpga_hwmon_priv *priv)
+{
+	if (!strcmp(type, ALTR_SOCFPGA_HWMON_TEMPERATURE)) {
+		if (priv->temperature_channels >= ALTR_SOCFPGA_HWMON_MAXSENSORS) {
+			dev_warn(dev,
+				 "Can't add temp node %s, too many channels",
+				 label);
+		return 0;
+		}
+
+		priv->altr_socfpga_temp_chan_names[priv->temperature_channels] = label;
+		priv->altr_socfpga_temp_chan[priv->temperature_channels] = val;
+		priv->temperature_channels++;
+		return 0;
+	}
+
+	if (!strcmp(type, ALTR_SOCFPGA_HWMON_VOLTAGE)) {
+		if (priv->voltage_channels >= ALTR_SOCFPGA_HWMON_MAXSENSORS) {
+			dev_warn(dev,
+				 "Can't add voltage node %s, too many channels",
+				 label);
+			return 0;
+		}
+
+		priv->altr_socfpga_volt_chan_names[priv->voltage_channels] = label;
+		priv->altr_socfpga_volt_chan[priv->voltage_channels] = val;
+		priv->voltage_channels++;
+		return 0;
+	}
+
+	dev_warn(dev, "unsupported sensor type %s", type);
+	return 0;
+}
+
+static int altr_socfpga_probe_child_from_dt(struct device *dev,
+					    struct device_node *child,
+					    struct altr_socfpga_hwmon_priv *priv)
+{
+	u32 val;
+	int ret;
+	struct device_node *grandchild;
+	const char *label;
+	const char *type;
+
+	of_property_read_string(child, "name", &type);
+	for_each_child_of_node(child, grandchild) {
+		ret = of_property_read_u32(grandchild, "reg", &val);
+		if (ret) {
+			dev_err(dev, "missing reg property of %pOFn\n",
+				grandchild);
+			return ret;
+		}
+		ret = of_property_read_string(grandchild, "label", &label);
+		if (ret) {
+			dev_err(dev, "missing label propoerty of %pOFn\n",
+				grandchild);
+			return ret;
+		}
+
+		altr_socfpga_add_channel(dev, type, val, label, priv);
+	}
+
+	return 0;
+}
+
+static int altr_socfpga_probe_from_dt(struct device *dev,
+				      struct altr_socfpga_hwmon_priv *priv)
+{
+	const struct device_node *np = dev->of_node;
+	struct device_node *child;
+	int ret;
+
+	/* Compatible with non-DT platforms */
+	if (!np)
+		return 0;
+
+	for_each_child_of_node(np, child) {
+		ret = altr_socfpga_probe_child_from_dt(dev, child, priv);
+		if (ret) {
+			of_node_put(child);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static int altr_socfpga_hwmon_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device *hwmon_dev;
+	struct altr_socfpga_hwmon_priv *priv;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->client.dev = dev;
+	priv->client.receive_cb = NULL;
+	priv->client.priv = priv;
+	priv->temperature_channels = 0;
+	priv->voltage_channels = 0;
+
+	ret = altr_socfpga_probe_from_dt(dev, priv);
+	if (ret) {
+		dev_err(dev, "Unable to probe from device tree\n");
+		return ret;
+	}
+
+	mutex_init(&priv->lock);
+
+	priv->chan = stratix10_svc_request_channel_byname(&priv->client,
+							  SVC_CLIENT_HWMON);
+	if (IS_ERR(priv->chan)) {
+		dev_err(dev, "couldn't get service channel %s defering probe...\n",
+			SVC_CLIENT_HWMON);
+		return -EPROBE_DEFER;
+	}
+
+	dev_info(dev, "Initialized %d temperature and %d voltage channels",
+		 priv->temperature_channels, priv->voltage_channels);
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, "altr_hwmon", priv,
+							 &altr_socfpga_hwmon_chip_info,
+							 NULL);
+
+	init_completion(&priv->completion);
+	platform_set_drvdata(pdev, priv);
+
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static void altr_socfpga_hwmon_remove(struct platform_device *pdev)
+{
+	struct altr_socfpga_hwmon_priv *priv = platform_get_drvdata(pdev);
+
+	stratix10_svc_free_channel(priv->chan);
+}
+
+static const struct of_device_id altr_socfpga_of_match[] = {
+	{ .compatible = "altr,socfpga-hwmon" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, altr_socfpga_of_match);
+
+static struct platform_driver altr_socfpga_hwmon_driver = {
+	.driver = {
+		.name = "altr-hwmon",
+		.of_match_table = altr_socfpga_of_match,
+	},
+	.probe = altr_socfpga_hwmon_probe,
+	.remove = altr_socfpga_hwmon_remove,
+};
+module_platform_driver(altr_socfpga_hwmon_driver);
+
+MODULE_AUTHOR("Altera Corporation");
+MODULE_DESCRIPTION("Altera SoC FPGA hardware monitoring features");
+MODULE_LICENSE("GPL");
-- 
2.43.7

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