Re: [PATCH hwmon-next 2/3] hwmon: (mlxreg-fan) Extend driver to support multiply PWM

[Guenter Roeck <linux@roeck-us.net>]

On 9/16/21 6:22 AM, Vadim Pasternak wrote:
> Add additional PWM attributes in order to support the systems, which
> can be equipped with up-to four PWM controllers. System capability of
> additional PWM support is validated through the reading of relevant
> registers.
> 
> Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
> ---
>   drivers/hwmon/mlxreg-fan.c | 55 +++++++++++++++++++++++++++++---------
>   1 file changed, 43 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/hwmon/mlxreg-fan.c b/drivers/hwmon/mlxreg-fan.c
> index 6e6c7437db94..930636868ef5 100644
> --- a/drivers/hwmon/mlxreg-fan.c
> +++ b/drivers/hwmon/mlxreg-fan.c
> @@ -13,6 +13,8 @@
>   #include <linux/thermal.h>
>   
>   #define MLXREG_FAN_MAX_TACHO		14
> +#define MLXREG_FAN_MAX_PWM		4
> +#define MLXREG_FAN_PWM_NOT_CONNECTED	0xff
>   #define MLXREG_FAN_MAX_STATE		10
>   #define MLXREG_FAN_MIN_DUTY		51	/* 20% */
>   #define MLXREG_FAN_MAX_DUTY		255	/* 100% */
> @@ -105,7 +107,7 @@ struct mlxreg_fan {
>   	void *regmap;
>   	struct mlxreg_core_platform_data *pdata;
>   	struct mlxreg_fan_tacho tacho[MLXREG_FAN_MAX_TACHO];
> -	struct mlxreg_fan_pwm pwm;
> +	struct mlxreg_fan_pwm pwm[MLXREG_FAN_MAX_PWM];
>   	int tachos_per_drwr;
>   	int samples;
>   	int divider;
> @@ -119,6 +121,7 @@ mlxreg_fan_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
>   {
>   	struct mlxreg_fan *fan = dev_get_drvdata(dev);
>   	struct mlxreg_fan_tacho *tacho;
> +	struct mlxreg_fan_pwm *pwm;
>   	u32 regval;
>   	int err;
>   
> @@ -169,9 +172,10 @@ mlxreg_fan_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
>   		break;
>   
>   	case hwmon_pwm:
> +		pwm = &fan->pwm[channel];
>   		switch (attr) {
>   		case hwmon_pwm_input:
> -			err = regmap_read(fan->regmap, fan->pwm.reg, &regval);
> +			err = regmap_read(fan->regmap, pwm->reg, &regval);
>   			if (err)
>   				return err;
>   
> @@ -195,6 +199,7 @@ mlxreg_fan_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
>   		 int channel, long val)
>   {
>   	struct mlxreg_fan *fan = dev_get_drvdata(dev);
> +	struct mlxreg_fan_pwm *pwm;
>   
>   	switch (type) {
>   	case hwmon_pwm:
> @@ -203,7 +208,8 @@ mlxreg_fan_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
>   			if (val < MLXREG_FAN_MIN_DUTY ||
>   			    val > MLXREG_FAN_MAX_DUTY)
>   				return -EINVAL;
> -			return regmap_write(fan->regmap, fan->pwm.reg, val);
> +			pwm = &fan->pwm[channel];
> +			return regmap_write(fan->regmap, pwm->reg, val);
>   		default:
>   			return -EOPNOTSUPP;
>   		}
> @@ -235,7 +241,7 @@ mlxreg_fan_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr,
>   		break;
>   
>   	case hwmon_pwm:
> -		if (!(((struct mlxreg_fan *)data)->pwm.connected))
> +		if (!(((struct mlxreg_fan *)data)->pwm[channel].connected))
>   			return 0;
>   
>   		switch (attr) {
> @@ -270,6 +276,9 @@ static const struct hwmon_channel_info *mlxreg_fan_hwmon_info[] = {
>   			   HWMON_F_INPUT | HWMON_F_FAULT,
>   			   HWMON_F_INPUT | HWMON_F_FAULT),
>   	HWMON_CHANNEL_INFO(pwm,
> +			   HWMON_PWM_INPUT,
> +			   HWMON_PWM_INPUT,
> +			   HWMON_PWM_INPUT,
>   			   HWMON_PWM_INPUT),
>   	NULL
>   };
> @@ -300,7 +309,7 @@ static int mlxreg_fan_get_cur_state(struct thermal_cooling_device *cdev,
>   	u32 regval;
>   	int err;
>   
> -	err = regmap_read(fan->regmap, fan->pwm.reg, &regval);
> +	err = regmap_read(fan->regmap, fan->pwm[0].reg, &regval);
>   	if (err) {
>   		dev_err(fan->dev, "Failed to query PWM duty\n");
>   		return err;
> @@ -339,7 +348,7 @@ static int mlxreg_fan_set_cur_state(struct thermal_cooling_device *cdev,
>   		for (i = state; i <= MLXREG_FAN_MAX_STATE; i++)
>   			fan->cooling_levels[i] = i;
>   
> -		err = regmap_read(fan->regmap, fan->pwm.reg, &regval);
> +		err = regmap_read(fan->regmap, fan->pwm[0].reg, &regval);
>   		if (err) {
>   			dev_err(fan->dev, "Failed to query PWM duty\n");
>   			return err;
> @@ -358,7 +367,7 @@ static int mlxreg_fan_set_cur_state(struct thermal_cooling_device *cdev,
>   
>   	/* Normalize the state to the valid speed range. */
>   	state = fan->cooling_levels[state];
> -	err = regmap_write(fan->regmap, fan->pwm.reg,
> +	err = regmap_write(fan->regmap, fan->pwm[0].reg,
>   			   MLXREG_FAN_PWM_STATE2DUTY(state));
>   	if (err) {
>   		dev_err(fan->dev, "Failed to write PWM duty\n");
> @@ -390,6 +399,22 @@ static int mlxreg_fan_connect_verify(struct mlxreg_fan *fan,
>   	return !!(regval & data->bit);
>   }
>   
> +static int mlxreg_pwm_connect_verify(struct mlxreg_fan *fan,
> +				     struct mlxreg_core_data *data)
> +{
> +	u32 regval;
> +	int err;
> +
> +	err = regmap_read(fan->regmap, data->reg, &regval);
> +	if (err) {
> +		dev_err(fan->dev, "Failed to query pwm register 0x%08x\n",
> +			data->reg);
> +		return err;
> +	}
> +
> +	return regval != MLXREG_FAN_PWM_NOT_CONNECTED;
> +}
> +
>   static int mlxreg_fan_speed_divider_get(struct mlxreg_fan *fan,
>   					struct mlxreg_core_data *data)
>   {
> @@ -418,8 +443,8 @@ 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, tacho_avail = 0, pwm_num = 0, pwm_avail = 0, i;
>   	struct mlxreg_core_data *data = pdata->data;
> -	int tacho_num = 0, tacho_avail = 0, i;
>   	bool configured = false;
>   	int err;
>   
> @@ -449,13 +474,19 @@ static int mlxreg_fan_config(struct mlxreg_fan *fan,
>   			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",
> +			if (pwm_num == MLXREG_FAN_MAX_TACHO) {
> +				dev_err(fan->dev, "too many pwm entries: %s\n",
>   					data->label);
>   				return -EINVAL;
>   			}
> -			fan->pwm.reg = data->reg;
> -			fan->pwm.connected = true;
> +
> +			err = mlxreg_pwm_connect_verify(fan, data);
> +			if (err)
> +				return err;
> +
> +			fan->pwm[pwm_num].reg = data->reg;
> +			fan->pwm[pwm_num].connected = true;

I don't see where pwm_num is ever increased. Also, given the context,
don't see why pwm_avail would be necessary. This is different to the
tacho code, which distinguishes between num and avail.

> +			pwm_avail++;
>   		} else if (strnstr(data->label, "conf", sizeof(data->label))) {
>   			if (configured) {
>   				dev_err(fan->dev, "duplicate conf entry: %s\n",
>