[PATCH net-next 5/6] eth: fbnic: report temperature and voltage alarms via hwmon

[Zinc Lim <limzhineng2@gmail.com>]

Building on the temperature and voltage thresholds stored in
fbnic_fw_cap, expose alarm attributes through the hwmon interface:
temp1_{min,max,crit}_alarm and in0_{min,max}_alarm.

Each alarm is computed by taking a live sensor reading and comparing it
against the corresponding stored threshold. The static thresholds
(min/max/crit) are returned first straight from fbnic_fw_cap without a
firmware round-trip, and unsupported attributes are rejected up front, so
only attributes that actually need a live value fall through to a single
sensor read that then feeds input and every alarm.

A threshold the firmware did not populate reports -ENODATA for both the
threshold attribute and its alarm.

Signed-off-by: Zinc Lim <limzhineng2@gmail.com>
---
 drivers/net/ethernet/meta/fbnic/fbnic_hwmon.c | 68 +++++++++++++++++--
 1 file changed, 61 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_hwmon.c b/drivers/net/ethernet/meta/fbnic/fbnic_hwmon.c
index 4938f7b39140..c5cddd9cef12 100644
--- a/drivers/net/ethernet/meta/fbnic/fbnic_hwmon.c
+++ b/drivers/net/ethernet/meta/fbnic/fbnic_hwmon.c
@@ -87,34 +87,84 @@ static int fbnic_hwmon_read_threshold(long thr, long *val)
 	return 0;
 }
 
+static int fbnic_hwmon_read_alarm(long a, long b, long *val)
+{
+	if (a == FBNIC_SENSOR_NO_DATA || b == FBNIC_SENSOR_NO_DATA)
+		return -ENODATA;
+
+	*val = a >= b;
+	return 0;
+}
+
 static int fbnic_hwmon_temp_read(struct fbnic_dev *fbd, u32 attr, long *val)
 {
+	int err;
+
 	switch (attr) {
-	case hwmon_temp_input:
-		return fbnic_hwmon_sensor_read(fbd, FBNIC_SENSOR_TEMP, val);
 	case hwmon_temp_min:
 		return fbnic_hwmon_read_threshold(fbd->fw_cap.temp.min, val);
 	case hwmon_temp_max:
 		return fbnic_hwmon_read_threshold(fbd->fw_cap.temp.max, val);
 	case hwmon_temp_crit:
 		return fbnic_hwmon_read_threshold(fbd->fw_cap.temp.crit, val);
+	case hwmon_temp_input:
+	case hwmon_temp_min_alarm:
+	case hwmon_temp_max_alarm:
+	case hwmon_temp_crit_alarm:
+		break;
 	default:
 		return -EOPNOTSUPP;
 	}
+
+	err = fbnic_hwmon_sensor_read(fbd, FBNIC_SENSOR_TEMP, val);
+	if (err)
+		return err;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		return 0;
+	case hwmon_temp_min_alarm:
+		return fbnic_hwmon_read_alarm(fbd->fw_cap.temp.min, *val, val);
+	case hwmon_temp_max_alarm:
+		return fbnic_hwmon_read_alarm(*val, fbd->fw_cap.temp.max, val);
+	case hwmon_temp_crit_alarm:
+		return fbnic_hwmon_read_alarm(*val, fbd->fw_cap.temp.crit, val);
+	}
+
+	return -EOPNOTSUPP;
 }
 
 static int fbnic_hwmon_in_read(struct fbnic_dev *fbd, u32 attr, long *val)
 {
+	int err;
+
 	switch (attr) {
-	case hwmon_in_input:
-		return fbnic_hwmon_sensor_read(fbd, FBNIC_SENSOR_VOLTAGE, val);
 	case hwmon_in_min:
 		return fbnic_hwmon_read_threshold(fbd->fw_cap.volt.min, val);
 	case hwmon_in_max:
 		return fbnic_hwmon_read_threshold(fbd->fw_cap.volt.max, val);
+	case hwmon_in_input:
+	case hwmon_in_min_alarm:
+	case hwmon_in_max_alarm:
+		break;
 	default:
 		return -EOPNOTSUPP;
 	}
+
+	err = fbnic_hwmon_sensor_read(fbd, FBNIC_SENSOR_VOLTAGE, val);
+	if (err)
+		return err;
+
+	switch (attr) {
+	case hwmon_in_input:
+		return 0;
+	case hwmon_in_min_alarm:
+		return fbnic_hwmon_read_alarm(fbd->fw_cap.volt.min, *val, val);
+	case hwmon_in_max_alarm:
+		return fbnic_hwmon_read_alarm(*val, fbd->fw_cap.volt.max, val);
+	}
+
+	return -EOPNOTSUPP;
 }
 
 static int fbnic_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
@@ -139,10 +189,14 @@ static const struct hwmon_ops fbnic_hwmon_ops = {
 
 static const struct hwmon_channel_info *fbnic_hwmon_info[] = {
 	HWMON_CHANNEL_INFO(temp,
-			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
-			   HWMON_T_CRIT),
+			   HWMON_T_INPUT |
+			   HWMON_T_MIN | HWMON_T_MIN_ALARM |
+			   HWMON_T_MAX | HWMON_T_MAX_ALARM |
+			   HWMON_T_CRIT | HWMON_T_CRIT_ALARM),
 	HWMON_CHANNEL_INFO(in,
-			   HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX),
+			   HWMON_I_INPUT |
+			   HWMON_I_MIN | HWMON_I_MIN_ALARM |
+			   HWMON_I_MAX | HWMON_I_MAX_ALARM),
 	NULL
 };
 
-- 
2.53.0-Meta