This patch adds support for hardware monitoring to the fbnic driver,
allowing for temperature and voltage sensor data to be exposed to
userspace via the HWMON interface. The driver registers a HWMON device
and provides callbacks for reading sensor data, enabling system
admins to monitor the health and operating conditions of fbnic.

Signed-off-by: Sanman Pradhan <sanman.p211993@gmail.com>
---
 drivers/net/ethernet/meta/fbnic/Makefile      |  1 +
 drivers/net/ethernet/meta/fbnic/fbnic.h       |  4 +
 drivers/net/ethernet/meta/fbnic/fbnic_hwmon.c | 81 +++++++++++++++++++
 drivers/net/ethernet/meta/fbnic/fbnic_pci.c   |  3 +
 4 files changed, 89 insertions(+)
 create mode 100644 drivers/net/ethernet/meta/fbnic/fbnic_hwmon.c

diff --git a/drivers/net/ethernet/meta/fbnic/Makefile b/drivers/net/ethernet/meta/fbnic/Makefile
index ea6214ca48e7..239b2258ec65 100644
--- a/drivers/net/ethernet/meta/fbnic/Makefile
+++ b/drivers/net/ethernet/meta/fbnic/Makefile
@@ -13,6 +13,7 @@ fbnic-y := fbnic_csr.o \
 	   fbnic_ethtool.o \
 	   fbnic_fw.o \
 	   fbnic_hw_stats.o \
+	   fbnic_hwmon.o \
 	   fbnic_irq.o \
 	   fbnic_mac.o \
 	   fbnic_netdev.o \
diff --git a/drivers/net/ethernet/meta/fbnic/fbnic.h b/drivers/net/ethernet/meta/fbnic/fbnic.h
index ad8ac5ac7be9..14751f16e125 100644
--- a/drivers/net/ethernet/meta/fbnic/fbnic.h
+++ b/drivers/net/ethernet/meta/fbnic/fbnic.h
@@ -24,6 +24,7 @@ struct fbnic_dev {
 	struct device *dev;
 	struct net_device *netdev;
 	struct dentry *dbg_fbd;
+	struct device *hwmon;

 	u32 __iomem *uc_addr0;
 	u32 __iomem *uc_addr4;
@@ -150,6 +151,9 @@ void fbnic_devlink_unregister(struct fbnic_dev *fbd);
 int fbnic_fw_enable_mbx(struct fbnic_dev *fbd);
 void fbnic_fw_disable_mbx(struct fbnic_dev *fbd);

+void fbnic_hwmon_register(struct fbnic_dev *fbd);
+void fbnic_hwmon_unregister(struct fbnic_dev *fbd);
+
 int fbnic_pcs_irq_enable(struct fbnic_dev *fbd);
 void fbnic_pcs_irq_disable(struct fbnic_dev *fbd);

diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_hwmon.c b/drivers/net/ethernet/meta/fbnic/fbnic_hwmon.c
new file mode 100644
index 000000000000..def8598aceec
--- /dev/null
+++ b/drivers/net/ethernet/meta/fbnic/fbnic_hwmon.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) Meta Platforms, Inc. and affiliates. */
+
+#include <linux/hwmon.h>
+
+#include "fbnic.h"
+#include "fbnic_mac.h"
+
+static int fbnic_hwmon_sensor_id(enum hwmon_sensor_types type)
+{
+	if (type == hwmon_temp)
+		return FBNIC_SENSOR_TEMP;
+	if (type == hwmon_in)
+		return FBNIC_SENSOR_VOLTAGE;
+
+	return -EOPNOTSUPP;
+}
+
+static umode_t fbnic_hwmon_is_visible(const void *drvdata,
+				      enum hwmon_sensor_types type,
+				      u32 attr, int channel)
+{
+	if (type == hwmon_temp && attr == hwmon_temp_input)
+		return 0444;
+	if (type == hwmon_in && attr == hwmon_in_input)
+		return 0444;
+
+	return 0;
+}
+
+static int fbnic_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
+			    u32 attr, int channel, long *val)
+{
+	struct fbnic_dev *fbd = dev_get_drvdata(dev);
+	const struct fbnic_mac *mac = fbd->mac;
+	int id;
+
+	id = fbnic_hwmon_sensor_id(type);
+	return id < 0 ? id : mac->get_sensor(fbd, id, val);
+}
+
+static const struct hwmon_ops fbnic_hwmon_ops = {
+	.is_visible = fbnic_hwmon_is_visible,
+	.read = fbnic_hwmon_read,
+};
+
+static const struct hwmon_channel_info *fbnic_hwmon_info[] = {
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
+	HWMON_CHANNEL_INFO(in, HWMON_I_INPUT),
+	NULL
+};
+
+static const struct hwmon_chip_info fbnic_chip_info = {
+	.ops = &fbnic_hwmon_ops,
+	.info = fbnic_hwmon_info,
+};
+
+void fbnic_hwmon_register(struct fbnic_dev *fbd)
+{
+	if (!IS_REACHABLE(CONFIG_HWMON))
+		return;
+
+	fbd->hwmon = hwmon_device_register_with_info(fbd->dev, "fbnic",
+						     fbd, &fbnic_chip_info,
+						     NULL);
+	if (IS_ERR(fbd->hwmon)) {
+		dev_notice(fbd->dev,
+			   "Failed to register hwmon device %pe\n",
+			   fbd->hwmon);
+		fbd->hwmon = NULL;
+	}
+}
+
+void fbnic_hwmon_unregister(struct fbnic_dev *fbd)
+{
+	if (!IS_REACHABLE(CONFIG_HWMON) || !fbd->hwmon)
+		return;
+
+	hwmon_device_unregister(fbd->hwmon);
+	fbd->hwmon = NULL;
+}
diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_pci.c b/drivers/net/ethernet/meta/fbnic/fbnic_pci.c
index 2c96980d150d..6cbbc2ee3e1f 100644
--- a/drivers/net/ethernet/meta/fbnic/fbnic_pci.c
+++ b/drivers/net/ethernet/meta/fbnic/fbnic_pci.c
@@ -296,6 +296,8 @@ static int fbnic_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	/* Capture snapshot of hardware stats so netdev can calculate delta */
 	fbnic_reset_hw_stats(fbd);

+	fbnic_hwmon_register(fbd);
+
 	if (!fbd->dsn) {
 		dev_warn(&pdev->dev, "Reading serial number failed\n");
 		goto init_failure_mode;
@@ -358,6 +360,7 @@ static void fbnic_remove(struct pci_dev *pdev)
 		fbnic_netdev_free(fbd);
 	}

+	fbnic_hwmon_unregister(fbd);
 	fbnic_dbg_fbd_exit(fbd);
 	fbnic_devlink_unregister(fbd);
 	fbnic_fw_disable_mbx(fbd);
--
2.43.5

On Mon, Jan 13, 2025 at 04:07:05PM -0800, Sanman Pradhan wrote:
> This patch adds support for hardware monitoring to the fbnic driver,
> allowing for temperature and voltage sensor data to be exposed to
> userspace via the HWMON interface. The driver registers a HWMON device
> and provides callbacks for reading sensor data, enabling system
> admins to monitor the health and operating conditions of fbnic.
> 
> Signed-off-by: Sanman Pradhan <sanman.p211993@gmail.com>
> ---
>  drivers/net/ethernet/meta/fbnic/Makefile      |  1 +
>  drivers/net/ethernet/meta/fbnic/fbnic.h       |  4 +
>  drivers/net/ethernet/meta/fbnic/fbnic_hwmon.c | 81 +++++++++++++++++++
>  drivers/net/ethernet/meta/fbnic/fbnic_pci.c   |  3 +
>  4 files changed, 89 insertions(+)
>  create mode 100644 drivers/net/ethernet/meta/fbnic/fbnic_hwmon.c
> 
> diff --git a/drivers/net/ethernet/meta/fbnic/Makefile b/drivers/net/ethernet/meta/fbnic/Makefile
> index ea6214ca48e7..239b2258ec65 100644

[...]

Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>

> 2.43.5