Add new FAN hwmon attribute for exposing FAN faults (fault is set in
case FAN tachometer is below allowed minimum).

Signed-off-by: Vadim Pasternak <vad...@mellanox.com>
Acked-by: Jiri Pirko <j...@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlxsw/core_hwmon.c | 62 +++++++++++++++++++++++-
 1 file changed, 60 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/core_hwmon.c 
b/drivers/net/ethernet/mellanox/mlxsw/core_hwmon.c
index 84185f8..dfd7adc 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/core_hwmon.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core_hwmon.c
@@ -44,6 +44,7 @@
 #define MLXSW_HWMON_TEMP_SENSOR_MAX_COUNT 127
 #define MLXSW_HWMON_ATTR_COUNT (MLXSW_HWMON_TEMP_SENSOR_MAX_COUNT * 4 + \
                                MLXSW_MFCR_TACHOS_MAX + MLXSW_MFCR_PWMS_MAX)
+#define MLXSW_HWMON_SPEED_MAX 50000    /* RPM */
 
 struct mlxsw_hwmon_attr {
        struct device_attribute dev_attr;
@@ -61,6 +62,7 @@ struct mlxsw_hwmon {
        struct attribute *attrs[MLXSW_HWMON_ATTR_COUNT + 1];
        struct mlxsw_hwmon_attr hwmon_attrs[MLXSW_HWMON_ATTR_COUNT];
        unsigned int attrs_count;
+       u16 tach_min;
 };
 
 static ssize_t mlxsw_hwmon_temp_show(struct device *dev,
@@ -152,6 +154,28 @@ static ssize_t mlxsw_hwmon_fan_rpm_show(struct device *dev,
        return sprintf(buf, "%u\n", mlxsw_reg_mfsm_rpm_get(mfsm_pl));
 }
 
+static ssize_t mlxsw_hwmon_fan_fault_show(struct device *dev,
+                                         struct device_attribute *attr,
+                                         char *buf)
+{
+       struct mlxsw_hwmon_attr *mlwsw_hwmon_attr =
+                       container_of(attr, struct mlxsw_hwmon_attr, dev_attr);
+       struct mlxsw_hwmon *mlxsw_hwmon = mlwsw_hwmon_attr->hwmon;
+       char mfsm_pl[MLXSW_REG_MFSM_LEN];
+       u16 tach;
+       int err;
+
+       mlxsw_reg_mfsm_pack(mfsm_pl, mlwsw_hwmon_attr->type_index);
+       err = mlxsw_reg_query(mlxsw_hwmon->core, MLXSW_REG(mfsm), mfsm_pl);
+       if (err) {
+               dev_err(mlxsw_hwmon->bus_info->dev, "Failed to query fan\n");
+               return err;
+       }
+       tach = mlxsw_reg_mfsm_rpm_get(mfsm_pl);
+
+       return sprintf(buf, "%u\n", (tach < mlxsw_hwmon->tach_min) ? 1 : 0);
+}
+
 static ssize_t mlxsw_hwmon_pwm_show(struct device *dev,
                                    struct device_attribute *attr,
                                    char *buf)
@@ -203,6 +227,7 @@ enum mlxsw_hwmon_attr_type {
        MLXSW_HWMON_ATTR_TYPE_TEMP_MAX,
        MLXSW_HWMON_ATTR_TYPE_TEMP_RST,
        MLXSW_HWMON_ATTR_TYPE_FAN_RPM,
+       MLXSW_HWMON_ATTR_TYPE_FAN_FAULT,
        MLXSW_HWMON_ATTR_TYPE_PWM,
 };
 
@@ -240,6 +265,12 @@ static void mlxsw_hwmon_attr_add(struct mlxsw_hwmon 
*mlxsw_hwmon,
                snprintf(mlxsw_hwmon_attr->name, sizeof(mlxsw_hwmon_attr->name),
                         "fan%u_input", num + 1);
                break;
+       case MLXSW_HWMON_ATTR_TYPE_FAN_FAULT:
+               mlxsw_hwmon_attr->dev_attr.show = mlxsw_hwmon_fan_fault_show;
+               mlxsw_hwmon_attr->dev_attr.attr.mode = 0444;
+               snprintf(mlxsw_hwmon_attr->name, sizeof(mlxsw_hwmon_attr->name),
+                        "fan%u_fault", num + 1);
+               break;
        case MLXSW_HWMON_ATTR_TYPE_PWM:
                mlxsw_hwmon_attr->dev_attr.show = mlxsw_hwmon_pwm_show;
                mlxsw_hwmon_attr->dev_attr.store = mlxsw_hwmon_pwm_store;
@@ -297,9 +328,9 @@ static int mlxsw_hwmon_fans_init(struct mlxsw_hwmon 
*mlxsw_hwmon)
 {
        char mfcr_pl[MLXSW_REG_MFCR_LEN] = {0};
        enum mlxsw_reg_mfcr_pwm_frequency freq;
+       u16 tacho_active, tach_min;
        unsigned int type_index;
        unsigned int num;
-       u16 tacho_active;
        u8 pwm_active;
        int err;
 
@@ -310,11 +341,38 @@ static int mlxsw_hwmon_fans_init(struct mlxsw_hwmon 
*mlxsw_hwmon)
        }
        mlxsw_reg_mfcr_unpack(mfcr_pl, &freq, &tacho_active, &pwm_active);
        num = 0;
+       /* Set tachometer to maximum value as the initial seed. */
+       mlxsw_hwmon->tach_min = MLXSW_HWMON_SPEED_MAX;
        for (type_index = 0; type_index < MLXSW_MFCR_TACHOS_MAX; type_index++) {
-               if (tacho_active & BIT(type_index))
+               if (tacho_active & BIT(type_index)) {
+                       char mfsl_pl[MLXSW_REG_MFSL_LEN] = {0};
+
                        mlxsw_hwmon_attr_add(mlxsw_hwmon,
                                             MLXSW_HWMON_ATTR_TYPE_FAN_RPM,
+                                            type_index, num);
+                       mlxsw_hwmon_attr_add(mlxsw_hwmon,
+                                            MLXSW_HWMON_ATTR_TYPE_FAN_FAULT,
                                             type_index, num++);
+                       /* Get tachometer minimum value. */
+                       mlxsw_reg_mfsl_pack(mfsl_pl, type_index, 0, 0);
+                       err = mlxsw_reg_query(mlxsw_hwmon->core,
+                                             MLXSW_REG(mfsl), mfsl_pl);
+                       if (err) {
+                               dev_err(mlxsw_hwmon->bus_info->dev, "Failed to 
query tachometer %d\n",
+                                       type_index);
+                               return err;
+                       }
+
+                       tach_min = mlxsw_reg_mfsl_tach_min_get(mfsl_pl);
+                       /* Store absolute minimal value of all tachometers for
+                        * alarm indication, because forward FANs could be
+                        * replaced with reversed and wise versa and in such
+                        * case the minimum values could be flipped.
+                        */
+                       mlxsw_hwmon->tach_min = min_t(u16,
+                                                     mlxsw_hwmon->tach_min,
+                                                     tach_min);
+               }
        }
        num = 0;
        for (type_index = 0; type_index < MLXSW_MFCR_PWMS_MAX; type_index++) {
-- 
2.1.4

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