On Tue, Dec 08, 2020 at 11:29:31AM +0200, Vadim Pasternak wrote:
> Add support for fan drawer's capability and present registers in order
> to set mapping between the fan drawers and tachometers. Some systems
> are equipped with fan drawers with one tachometer inside. Others with
> fan drawers with several tachometers inside. Using present register
> along with tachometer-to-drawer mapping allows to skip reading missed
> tachometers and expose input for them as zero, instead of exposing
> fault code returned by hardware.
>
> Signed-off-by: Vadim Pasternak <vadimp@xxxxxxxxxx>
> ---
> drivers/hwmon/mlxreg-fan.c | 46 +++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 45 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwmon/mlxreg-fan.c b/drivers/hwmon/mlxreg-fan.c
> index ed8d59d4eecb..ab743929a6cd 100644
> --- a/drivers/hwmon/mlxreg-fan.c
> +++ b/drivers/hwmon/mlxreg-fan.c
> @@ -67,11 +67,13 @@
> * @connected: indicates if tachometer is connected;
> * @reg: register offset;
> * @mask: fault mask;
> + * @prsnt: present register offset;
> */
> struct mlxreg_fan_tacho {
> bool connected;
> u32 reg;
> u32 mask;
> + u32 prsnt;
> };
>
> /*
> @@ -92,6 +94,7 @@ struct mlxreg_fan_pwm {
> * @regmap: register map of parent device;
> * @tacho: tachometer data;
> * @pwm: PWM data;
> + * @tachos_per_drwr - number of tachometers per drawer;
> * @samples: minimum allowed samples per pulse;
> * @divider: divider value for tachometer RPM calculation;
> * @cooling: cooling device levels;
> @@ -103,6 +106,7 @@ struct mlxreg_fan {
> struct mlxreg_core_platform_data *pdata;
> struct mlxreg_fan_tacho tacho[MLXREG_FAN_MAX_TACHO];
> struct mlxreg_fan_pwm pwm;
> + int tachos_per_drwr;
> int samples;
> int divider;
> u8 cooling_levels[MLXREG_FAN_MAX_STATE + 1];
> @@ -123,6 +127,26 @@ mlxreg_fan_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
> tacho = &fan->tacho[channel];
> switch (attr) {
> case hwmon_fan_input:
> + /*
> + * Check FAN presence: FAN related bit in presence register is one,
> + * if FAN is not physically connected, zero - otherwise.
> + */
> + if (tacho->prsnt) {
> + err = regmap_read(fan->regmap, tacho->prsnt, ®val);
> + if (err)
> + return err;
> +
> + /*
> + * Map channel to presence bit - drawer can be equipped with
> + * one or few FANs, while presence is indicated per drawer.
> + */
> + if ((BIT(channel / fan->tachos_per_drwr) & regval)) {
The outer double (( )) is pointless.
> + /* FAN is not connected - return zero for FAN speed. */
> + *val = 0;
> + return 0;
> + }
Assuming fan configuration is static, it might make more sense
to disable the attribute in the is_visible function instead of
checking the presence condition over and over again.
> + }
> +
> err = regmap_read(fan->regmap, tacho->reg, ®val);
> if (err)
> return err;
> @@ -388,9 +412,11 @@ static int mlxreg_fan_speed_divider_get(struct mlxreg_fan *fan,
> static int mlxreg_fan_config(struct mlxreg_fan *fan,
> struct mlxreg_core_platform_data *pdata)
> {
> + int tacho_num = 0, regval, regsize, drwr_avail = 0, tacho_avail = 0, i;
> struct mlxreg_core_data *data = pdata->data;
> bool configured = false;
> - int tacho_num = 0, i;
> + unsigned long drwrs;
> + u32 bit;
> int err;
>
> fan->samples = MLXREG_FAN_TACHO_SAMPLES_PER_PULSE_DEF;
> @@ -415,7 +441,9 @@ static int mlxreg_fan_config(struct mlxreg_fan *fan,
>
> fan->tacho[tacho_num].reg = data->reg;
> fan->tacho[tacho_num].mask = data->mask;
> + fan->tacho[tacho_num].prsnt = data->reg_prsnt;
> fan->tacho[tacho_num++].connected = true;
> + tacho_avail++;
> } else if (strnstr(data->label, "pwm", sizeof(data->label))) {
> if (fan->pwm.connected) {
> dev_err(fan->dev, "duplicate pwm entry: %s\n",
> @@ -453,6 +481,22 @@ static int mlxreg_fan_config(struct mlxreg_fan *fan,
> }
> }
>
> + if (pdata->capability) {
> + /* Obtain the number of FAN drawers, supported by system. */
> + err = regmap_read(fan->regmap, pdata->capability, ®val);
> + if (err) {
> + dev_err(fan->dev, "Failed to query capability register 0x%08x\n",
> + pdata->capability);
> + return err;
> + }
> + regsize = regmap_get_val_bytes(fan->regmap);
> + drwrs = regval;
> + for_each_set_bit(bit, &drwrs, 8 * regsize)
> + drwr_avail++;
Why not just hweight_long() or hweight32() ? And what is the point
of the extra variable ? It is also odd that regval is an int while
regmap_read() takes a pointer to an unsigned int as parameter. So
the returned value is converted to int and then to unsigned long.
Yes, I understand this only takes bits into account which are reported
by regmap_get_val_bytes, but regmap_read already takes that into account
and won't set bits larger than indicated by val_bytes. So all I can see
is a lot of complexity with no gain.
> + /* Set the number of tachometers per one drawer. */
> + fan->tachos_per_drwr = tacho_avail / drwr_avail;
What if no bit is set, ie drwr_avail == 0 ?
Also, what guarantees that tachos_per_drwr is not 0 ?
> + }
> +
> /* Init cooling levels per PWM state. */
> for (i = 0; i < MLXREG_FAN_SPEED_MIN_LEVEL; i++)
> fan->cooling_levels[i] = MLXREG_FAN_SPEED_MIN_LEVEL;
> --
> 2.11.0
>
