software: kernel: Use HWMON API to expose Temperature

Information from sensors like temperature, which are useful for user-space, can be exposed via sysfs. Earlier, the driver developers had to take care of defining the attributes, initiating them, and perform other related jobs. But since a long time, the HWMON framework in Linux has developed significantly. And, utilizing it will reduce lot of maintainence work for the developers. All the sysfs related part is handled by the framework which also allows user-space tools, like lm-sensors, to provide the data to the user in a simplified manner. Signed-off-by: Vaibhav Gupta <vaibhav.gupta@cern.ch>

software: kernel: Use HWMON API to expose Temperature
Information from sensors like temperature, which are useful for user-space, can be exposed via sysfs. Earlier, the driver developers had to take care of defining the attributes, initiating them, and perform other related jobs. But since a long time, the HWMON framework in Linux has developed significantly. And, utilizing it will reduce lot of maintainence work for the developers. All the sysfs related part is handled by the framework which also allows user-space tools, like lm-sensors, to provide the data to the user in a simplified manner. Signed-off-by: Vaibhav Gupta <vaibhav.gupta@cern.ch>
d0bb7817 · Vaibhav Gupta · Federico Vaga · 6160f63b · d0bb7817 · d0bb7817
Commit d0bb7817 authored Feb 02, 2023 by Vaibhav Gupta Committed by Federico Vaga Feb 14, 2023
Showing with 106 additions and 0 deletions

Kbuild software/kernel/Kbuild +1 -0

fa-core.c software/kernel/fa-core.c +6 -0

fa-hwmon.c software/kernel/fa-hwmon.c +91 -0

fmc-adc-100m14b4cha-private.h software/kernel/fmc-adc-100m14b4cha-private.h +8 -0

No files found.
--- a/software/kernel/Kbuild
+++ b/software/kernel/Kbuild
@@ -61,6 +61,7 @@ fmc-adc-100m14b4ch-y += fa-irq.o
 fmc-adc-100m14b4ch-y += fa-debug.o
 fmc-adc-100m14b4ch-y += fa-dma.o
 fmc-adc-100m14b4ch-y += spi.o
+fmc-adc-100m14b4ch-y += fa-hwmon.o

 fmc-adc-100m14b4ch-spec-objs := fmc-adc-100m14b4ch-spec-core.o
 fmc-adc-100m14b4ch-svec-objs := fmc-adc-100m14b4ch-svec-core.o
--- a/software/kernel/fa-core.c
+++ b/software/kernel/fa-core.c
@@ -880,6 +880,12 @@ int fa_probe(struct platform_device *pdev)
 	if (err < 0)
 		goto out_irq;

+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,10,0)
+	err = fa_hwmon_init(fa);
+	if(err != 0)
+		dev_err(fa->msgdev, "Could not create HWMON device: %d", err);
+#endif
+
 	return 0;

 out_irq:

--- a/software/kernel/fa-hwmon.c
+++ b/software/kernel/fa-hwmon.c
+// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2023 CERN (home.cern)
+
+/*
+ * Author: Vaibhav Gupta <vaibhav.gupta@cern.ch>
+ *
+ * Hardware Monitoring for fa-dev
+ */
+
+#include <linux/hwmon.h>
+#include "fmc-adc-100m14b4cha-private.h"
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,10,0)
+
+static umode_t fa_hwmon_temp_is_visible(const void *_data,
+				  enum hwmon_sensor_types type, u32 attr,
+				  int channel)
+{
+	return 0444;
+}
+
+static int fa_hwmon_temp_read(struct device *dev, enum hwmon_sensor_types type,
+				u32 attr, int channel, long *val)
+{
+	struct fa_dev *fa = dev_get_drvdata(dev);
+
+	*val = fa_temperature_read(fa);
+
+	return 0;
+}
+
+static int fa_hwmon_temp_sensor_id_read(struct device *dev,
+				   enum hwmon_sensor_types type,
+				   u32 attr, int channel, const char **str)
+{
+	struct fa_dev *fa = dev_get_drvdata(dev);
+
+	*str = fa->hwmon_temp_sensor_id;
+
+	return 0;
+}
+
+static const struct hwmon_channel_info *fa_hwmon_info[] = {
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_LABEL),
+	NULL
+};
+
+static const struct hwmon_ops fa_hwmon_temp_ops = {
+	.is_visible = fa_hwmon_temp_is_visible,
+	.read = fa_hwmon_temp_read,
+	.read_string = fa_hwmon_temp_sensor_id_read
+};
+
+static const struct hwmon_chip_info fa_hwmon_temp_chip_info = {
+	.ops = &fa_hwmon_temp_ops,
+	.info = fa_hwmon_info,
+};
+
+int fa_hwmon_init(struct fa_dev *fa)
+{
+	int size;
+	char device_type[] = "Temperature - FMC ADC 100M14B4C - ";
+	struct device *dev = &fa->pdev->dev;
+
+	fa->hwmon_dev = devm_hwmon_device_register_with_info(dev,
+							     "fa_temperature",
+							     fa,
+							     &fa_hwmon_temp_chip_info,
+							     NULL);
+	if(!IS_ERR(fa->hwmon_dev)) {
+		size = strlen(dev_name(&fa->slot->dev));
+		size += strlen(device_type);
+		size++;
+
+		fa->hwmon_temp_sensor_id = devm_kzalloc(fa->hwmon_dev,
+							size, GFP_KERNEL);
+		if(!fa->hwmon_temp_sensor_id) {
+			devm_hwmon_device_unregister(dev);
+			return -ENOMEM;
+		}
+
+		snprintf(fa->hwmon_temp_sensor_id, size, "%s%s",
+			 device_type, dev_name(&fa->slot->dev));
+
+		return 0;
+	}
+
+	return PTR_ERR(fa->hwmon_dev);
+}
+
+#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(5,10,0) */
--- a/software/kernel/fmc-adc-100m14b4cha-private.h
+++ b/software/kernel/fmc-adc-100m14b4cha-private.h
@@ -347,6 +347,10 @@ struct fa_dev {
 	unsigned long		next_t;
 	int			temp;	/* temperature: scaled by 4 bits */

+	/* HWMON */
+	char *hwmon_temp_sensor_id;
+	struct device *hwmon_dev;
+
 	/* Calibration Data */
 	struct fa_calib calib;
 	int32_t range[FA100M14B4C_NCHAN];
@@ -567,4 +571,8 @@ extern void fa_calib_config_chan(struct fa_dev *fa, unsigned int chan,
 extern int fa_debug_init(struct fa_dev *fa);
 extern void fa_debug_exit(struct fa_dev *fa);

+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,10,0)
+extern int fa_hwmon_init(struct fa_dev *fa);
+#endif
+
 #endif /*  FMC_ADC_H_ */