[PATCH 4/6] hwmon: amd_energy: let user enable/disable the sw accumulation

[Naveen Krishna Chatradhi <nchatrad@amd.com>]

Provide an option "accumulator_status" via sysfs to enable/disable
the software accumulation of energy counters.

Signed-off-by: Naveen Krishna Chatradhi <nchatrad@amd.com>
---
 drivers/hwmon/amd_energy.c | 104 ++++++++++++++++++++++++++++++-------
 1 file changed, 86 insertions(+), 18 deletions(-)

diff --git a/drivers/hwmon/amd_energy.c b/drivers/hwmon/amd_energy.c
index 96c61784d05c..c294bea56c02 100644
--- a/drivers/hwmon/amd_energy.c
+++ b/drivers/hwmon/amd_energy.c
@@ -32,6 +32,8 @@
 #define AMD_ENERGY_UNIT_MASK	0x01F00
 #define AMD_ENERGY_MASK		0xFFFFFFFF
 
+static struct device_attribute accumulate_attr;
+
 struct sensor_accumulator {
 	u64 energy_ctr;
 	u64 prev_value;
@@ -42,10 +44,12 @@ struct amd_energy_data {
 	const struct hwmon_channel_info *info[2];
 	struct hwmon_chip_info chip;
 	struct task_struct *wrap_accumulate;
+	struct device *hwmon_dev;
 	/* Lock around the accumulator */
 	struct mutex lock;
 	/* An accumulator for each core and socket */
 	struct sensor_accumulator *accums;
+	bool accumulator_status;
 	/* Energy Status Units */
 	u64 energy_units;
 	unsigned int timeout;
@@ -128,13 +132,15 @@ static void amd_add_delta(struct amd_energy_data *data, int ch,
 	rdmsrl_safe_on_cpu(cpu, reg, &input);
 	input &= AMD_ENERGY_MASK;
 
-	accum = &data->accums[ch];
-	if (input >= accum->prev_value)
-		input += accum->energy_ctr -
-				accum->prev_value;
-	else
-		input += UINT_MAX - accum->prev_value +
-				accum->energy_ctr;
+	if (data->accumulator_status) {
+		accum = &data->accums[ch];
+		if (input >= accum->prev_value)
+			input += accum->energy_ctr -
+					accum->prev_value;
+		else
+			input += UINT_MAX - accum->prev_value +
+					accum->energy_ctr;
+	}
 
 	/* Energy consumed = (1/(2^ESU) * RAW * 1000000UL) μJoules */
 	*val = div64_ul(input * 1000000UL, BIT(data->energy_units));
@@ -264,9 +270,67 @@ static int amd_create_sensor(struct device *dev,
 	return 0;
 }
 
+static ssize_t amd_energy_accumulate_show(struct device *dev,
+					  struct device_attribute *dev_attr,
+					  char *buf)
+{
+	struct amd_energy_data *data = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", data->accumulator_status);
+}
+
+static ssize_t amd_energy_accumulate_store(struct device *dev,
+					   struct device_attribute *dev_attr,
+					   const char *buf, size_t count)
+{
+	struct amd_energy_data *data = dev_get_drvdata(dev);
+	bool input;
+	int ret;
+
+	ret = kstrtobool(buf, &input);
+	if (ret)
+		return ret;
+
+	if (data->accumulator_status == input)
+		return count;
+
+	if (input) {
+		memset(data->accums, 0, (data->nr_cpus + data->nr_socks) *
+			sizeof(struct sensor_accumulator));
+
+		if (!data->wrap_accumulate) {
+			data->wrap_accumulate =
+				kthread_run(energy_accumulator,
+					    data, "%s", dev_name(dev));
+			if (IS_ERR(data->wrap_accumulate))
+				return PTR_ERR(data->wrap_accumulate);
+		}
+	} else {
+		if (data && data->wrap_accumulate) {
+			ret = kthread_stop(data->wrap_accumulate);
+			if (ret)
+				return ret;
+			data->wrap_accumulate = NULL;
+		}
+	}
+	data->accumulator_status = input;
+
+	return count;
+}
+
+static int create_accumulate_status_file(struct amd_energy_data *data)
+{
+	accumulate_attr.attr.name = "accumulator_status";
+	accumulate_attr.attr.mode = 0664;
+	accumulate_attr.show = amd_energy_accumulate_show;
+	accumulate_attr.store = amd_energy_accumulate_store;
+
+	return sysfs_create_file(&data->hwmon_dev->kobj,
+				 &accumulate_attr.attr);
+}
+
 static int amd_energy_probe(struct platform_device *pdev)
 {
-	struct device *hwmon_dev;
 	struct amd_energy_data *data;
 	struct device *dev = &pdev->dev;
 	int ret;
@@ -290,12 +354,12 @@ static int amd_energy_probe(struct platform_device *pdev)
 	mutex_init(&data->lock);
 	get_energy_units(data);
 
-	hwmon_dev = devm_hwmon_device_register_with_info(dev, DRVNAME,
-							 data,
-							 &data->chip,
-							 NULL);
-	if (IS_ERR(hwmon_dev))
-		return PTR_ERR(hwmon_dev);
+	data->hwmon_dev = devm_hwmon_device_register_with_info(dev, DRVNAME,
+							       data,
+							       &data->chip,
+							       NULL);
+	if (IS_ERR(data->hwmon_dev))
+		return PTR_ERR(data->hwmon_dev);
 
 	/* Once in 3 minutes for a resolution of 1/2*16 */
 	if (data->energy_units == 0x10)
@@ -305,10 +369,12 @@ static int amd_energy_probe(struct platform_device *pdev)
 	if (data->energy_units == 0x6)
 		data->timeout = 3 * 24 * 60 * 60;
 
-	data->wrap_accumulate = kthread_run(energy_accumulator, data,
-					    "%s", dev_name(hwmon_dev));
-	if (IS_ERR(data->wrap_accumulate))
-		return PTR_ERR(data->wrap_accumulate);
+	/* Disabling the energy accumulation by default */
+	data->accumulator_status = 0;
+
+	ret = create_accumulate_status_file(data);
+	if (ret)
+		return ret;
 
 	return 0;
 }
@@ -317,6 +383,8 @@ static int amd_energy_remove(struct platform_device *pdev)
 {
 	struct amd_energy_data *data = dev_get_drvdata(&pdev->dev);
 
+	sysfs_remove_file(&data->hwmon_dev->kobj, &accumulate_attr.attr);
+
 	if (data && data->wrap_accumulate)
 		kthread_stop(data->wrap_accumulate);
 
-- 
2.26.2