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 <saikrishnag@marvell.com>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/20240704-feature_poe_power_cap-v6-4-320003204264@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 161 insertions, 11 deletions

diff --git a/drivers/net/pse-pd/pse_core.c b/drivers/net/pse-pd/pse_core.c
index 795ab264eaf2..16f364b3473b 100644
--- a/drivers/net/pse-pd/pse_core.c
+++ b/drivers/net/pse-pd/pse_core.c
@@ -265,10 +265,113 @@ static int pse_pi_disable(struct regulator_dev *rdev)
 	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
@@ -298,7 +401,9 @@ devm_pse_pi_regulator_register(struct pse_controller_dev *pcdev,
 	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;
@@ -626,6 +731,23 @@ out:
 }
 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
@@ -638,19 +760,10 @@ int pse_ethtool_get_status(struct pse_control *psec,
 			   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;
@@ -732,6 +845,43 @@ int pse_ethtool_set_config(struct pse_control *psec,
 }
 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)
 {
 	return psec->pcdev->types & ETHTOOL_PSE_PODL;