net: pse-pd: Add new power limit get and set c33 features

This patch add a way to get and set the power limit of a PSE PI.
For that it uses regulator API callbacks wrapper like get_voltage() and
get/set_current_limit() as power is simply V * I.
We used mW unit as defined by the IEEE 802.3-2022 standards.

set_current_limit() uses the voltage return by get_voltage() and the
desired power limit to calculate the current limit. get_voltage() callback
is then mandatory to set the power limit.

get_current_limit() callback is by default looking at a driver callback
and fallback to extracting the current limit from _pse_ethtool_get_status()
if the driver does not set its callback. We prefer let the user the choice
because ethtool_get_status return much more information than the current
limit.

expand pse status with c33_pw_limit_ranges to return the ranges available
to configure the power limit.

Reviewed-by: Sai Krishna <[e-mail]>
Acked-by: Oleksij Rempel <[e-mail]>
Signed-off-by: Kory Maincent <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/pse-pd/pse_core.c

···
 	return ret;
 }
 
+static int _pse_pi_get_voltage(struct regulator_dev *rdev)
+{
+	struct pse_controller_dev *pcdev = rdev_get_drvdata(rdev);
+	const struct pse_controller_ops *ops;
+	int id;
+
+	ops = pcdev->ops;
+	if (!ops->pi_get_voltage)
+		return -EOPNOTSUPP;
+
+	id = rdev_get_id(rdev);
+	return ops->pi_get_voltage(pcdev, id);
+}
+
+static int pse_pi_get_voltage(struct regulator_dev *rdev)
+{
+	struct pse_controller_dev *pcdev = rdev_get_drvdata(rdev);
+	int ret;
+
+	mutex_lock(&pcdev->lock);
+	ret = _pse_pi_get_voltage(rdev);
+	mutex_unlock(&pcdev->lock);
+
+	return ret;
+}
+
+static int _pse_ethtool_get_status(struct pse_controller_dev *pcdev,
+				   int id,
+				   struct netlink_ext_ack *extack,
+				   struct pse_control_status *status);
+
+static int pse_pi_get_current_limit(struct regulator_dev *rdev)
+{
+	struct pse_controller_dev *pcdev = rdev_get_drvdata(rdev);
+	const struct pse_controller_ops *ops;
+	struct netlink_ext_ack extack = {};
+	struct pse_control_status st = {};
+	int id, uV, ret;
+	s64 tmp_64;
+
+	ops = pcdev->ops;
+	id = rdev_get_id(rdev);
+	mutex_lock(&pcdev->lock);
+	if (ops->pi_get_current_limit) {
+		ret = ops->pi_get_current_limit(pcdev, id);
+		goto out;
+	}
+
+	/* If pi_get_current_limit() callback not populated get voltage
+	 * from pi_get_voltage() and power limit from ethtool_get_status()
+	 *  to calculate current limit.
+	 */
+	ret = _pse_pi_get_voltage(rdev);
+	if (!ret) {
+		dev_err(pcdev->dev, "Voltage null\n");
+		ret = -ERANGE;
+		goto out;
+	}
+	if (ret < 0)
+		goto out;
+	uV = ret;
+
+	ret = _pse_ethtool_get_status(pcdev, id, &extack, &st);
+	if (ret)
+		goto out;
+
+	if (!st.c33_avail_pw_limit) {
+		ret = -ENODATA;
+		goto out;
+	}
+
+	tmp_64 = st.c33_avail_pw_limit;
+	tmp_64 *= 1000000000ull;
+	/* uA = mW * 1000000000 / uV */
+	ret = DIV_ROUND_CLOSEST_ULL(tmp_64, uV);
+
+out:
+	mutex_unlock(&pcdev->lock);
+	return ret;
+}
+
+static int pse_pi_set_current_limit(struct regulator_dev *rdev, int min_uA,
+				    int max_uA)
+{
+	struct pse_controller_dev *pcdev = rdev_get_drvdata(rdev);
+	const struct pse_controller_ops *ops;
+	int id, ret;
+
+	ops = pcdev->ops;
+	if (!ops->pi_set_current_limit)
+		return -EOPNOTSUPP;
+
+	id = rdev_get_id(rdev);
+	mutex_lock(&pcdev->lock);
+	ret = ops->pi_set_current_limit(pcdev, id, max_uA);
+	mutex_unlock(&pcdev->lock);
+
+	return ret;
+}
+
 static const struct regulator_ops pse_pi_ops = {
 	.is_enabled = pse_pi_is_enabled,
 	.enable = pse_pi_enable,
 	.disable = pse_pi_disable,
+	.get_voltage = pse_pi_get_voltage,
+	.get_current_limit = pse_pi_get_current_limit,
+	.set_current_limit = pse_pi_set_current_limit,
 };
 
 static int
···
 	rdesc->ops = &pse_pi_ops;
 	rdesc->owner = pcdev->owner;
 
-	rinit_data->constraints.valid_ops_mask = REGULATOR_CHANGE_STATUS;
+	rinit_data->constraints.valid_ops_mask = REGULATOR_CHANGE_STATUS |
+						 REGULATOR_CHANGE_CURRENT;
+	rinit_data->constraints.max_uA = MAX_PI_CURRENT;
 	rinit_data->supply_regulator = "vpwr";
 
 	rconfig.dev = pcdev->dev;
···
 }
 EXPORT_SYMBOL_GPL(of_pse_control_get);
 
+static int _pse_ethtool_get_status(struct pse_controller_dev *pcdev,
+				   int id,
+				   struct netlink_ext_ack *extack,
+				   struct pse_control_status *status)
+{
+	const struct pse_controller_ops *ops;
+
+	ops = pcdev->ops;
+	if (!ops->ethtool_get_status) {
+		NL_SET_ERR_MSG(extack,
+			       "PSE driver does not support status report");
+		return -EOPNOTSUPP;
+	}
+
+	return ops->ethtool_get_status(pcdev, id, extack, status);
+}
+
 /**
  * pse_ethtool_get_status - get status of PSE control
  * @psec: PSE control pointer
···
 			   struct netlink_ext_ack *extack,
 			   struct pse_control_status *status)
 {
-	const struct pse_controller_ops *ops;
 	int err;
 
-	ops = psec->pcdev->ops;
-
-	if (!ops->ethtool_get_status) {
-		NL_SET_ERR_MSG(extack,
-			       "PSE driver does not support status report");
-		return -EOPNOTSUPP;
-	}
-
 	mutex_lock(&psec->pcdev->lock);
-	err = ops->ethtool_get_status(psec->pcdev, psec->id, extack, status);
+	err = _pse_ethtool_get_status(psec->pcdev, psec->id, extack, status);
 	mutex_unlock(&psec->pcdev->lock);
 
 	return err;
···
 	return err;
 }
 EXPORT_SYMBOL_GPL(pse_ethtool_set_config);
+
+/**
+ * pse_ethtool_set_pw_limit - set PSE control power limit
+ * @psec: PSE control pointer
+ * @extack: extack for reporting useful error messages
+ * @pw_limit: power limit value in mW
+ *
+ * Return: 0 on success and failure value on error
+ */
+int pse_ethtool_set_pw_limit(struct pse_control *psec,
+			     struct netlink_ext_ack *extack,
+			     const unsigned int pw_limit)
+{
+	int uV, uA, ret;
+	s64 tmp_64;
+
+	ret = regulator_get_voltage(psec->ps);
+	if (!ret) {
+		NL_SET_ERR_MSG(extack,
+			       "Can't calculate the current, PSE voltage read is 0");
+		return -ERANGE;
+	}
+	if (ret < 0) {
+		NL_SET_ERR_MSG(extack,
+			       "Error reading PSE voltage");
+		return ret;
+	}
+	uV = ret;
+
+	tmp_64 = pw_limit;
+	tmp_64 *= 1000000000ull;
+	/* uA = mW * 1000000000 / uV */
+	uA = DIV_ROUND_CLOSEST_ULL(tmp_64, uV);
+
+	return regulator_set_current_limit(psec->ps, 0, uA);
+}
+EXPORT_SYMBOL_GPL(pse_ethtool_set_pw_limit);
 
 bool pse_has_podl(struct pse_control *psec)
 {

include/linux/pse-pd/pse.h

···
 #include <linux/list.h>
 #include <uapi/linux/ethtool.h>
 
+/* Maximum current in uA according to IEEE 802.3-2022 Table 145-1 */
+#define MAX_PI_CURRENT 1920000
+
 struct phy_device;
 struct pse_controller_dev;
 
···
  * @c33_actual_pw: power currently delivered by the PSE in mW
  *	IEEE 802.3-2022 30.9.1.1.23 aPSEActualPower
  * @c33_ext_state_info: extended state information of the PSE
+ * @c33_avail_pw_limit: available power limit of the PSE in mW
+ *	IEEE 802.3-2022 145.2.5.4 pse_avail_pwr
+ * @c33_pw_limit_ranges: supported power limit configuration range. The driver
+ *	is in charge of the memory allocation.
+ * @c33_pw_limit_nb_ranges: number of supported power limit configuration
+ *	ranges
  */
 struct pse_control_status {
 	enum ethtool_podl_pse_admin_state podl_admin_state;
···
 	u32 c33_pw_class;
 	u32 c33_actual_pw;
 	struct ethtool_c33_pse_ext_state_info c33_ext_state_info;
+	u32 c33_avail_pw_limit;
+	struct ethtool_c33_pse_pw_limit_range *c33_pw_limit_ranges;
+	u32 c33_pw_limit_nb_ranges;
 };
 
 /**
···
  *		   May also return negative errno.
  * @pi_enable: Configure the PSE PI as enabled.
  * @pi_disable: Configure the PSE PI as disabled.
+ * @pi_get_voltage: Return voltage similarly to get_voltage regulator
+ *		    callback.
+ * @pi_get_current_limit: Get the configured current limit similarly to
+ *			  get_current_limit regulator callback.
+ * @pi_set_current_limit: Configure the current limit similarly to
+ *			  set_current_limit regulator callback.
+ *			  Should not return an error in case of MAX_PI_CURRENT
+ *			  current value set.
  */
 struct pse_controller_ops {
 	int (*ethtool_get_status)(struct pse_controller_dev *pcdev,
···
 	int (*pi_is_enabled)(struct pse_controller_dev *pcdev, int id);
 	int (*pi_enable)(struct pse_controller_dev *pcdev, int id);
 	int (*pi_disable)(struct pse_controller_dev *pcdev, int id);
+	int (*pi_get_voltage)(struct pse_controller_dev *pcdev, int id);
+	int (*pi_get_current_limit)(struct pse_controller_dev *pcdev,
+				    int id);
+	int (*pi_set_current_limit)(struct pse_controller_dev *pcdev,
+				    int id, int max_uA);
 };
 
 struct module;
···
 int pse_ethtool_set_config(struct pse_control *psec,
 			   struct netlink_ext_ack *extack,
 			   const struct pse_control_config *config);
+int pse_ethtool_set_pw_limit(struct pse_control *psec,
+			     struct netlink_ext_ack *extack,
+			     const unsigned int pw_limit);
+int pse_ethtool_get_pw_limit(struct pse_control *psec,
+			     struct netlink_ext_ack *extack);
 
 bool pse_has_podl(struct pse_control *psec);
 bool pse_has_c33(struct pse_control *psec);
···
 static inline int pse_ethtool_set_config(struct pse_control *psec,
 					 struct netlink_ext_ack *extack,
 					 const struct pse_control_config *config)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int pse_ethtool_set_pw_limit(struct pse_control *psec,
+					   struct netlink_ext_ack *extack,
+					   const unsigned int pw_limit)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int pse_ethtool_get_pw_limit(struct pse_control *psec,
+					   struct netlink_ext_ack *extack)
 {
 	return -EOPNOTSUPP;
 }