net: pse-pd: Use regulator framework within PSE framework

Integrate the regulator framework to the PSE framework for enhanced
access to features such as voltage, power measurement, and limits, which
are akin to regulators. Additionally, PSE features like port priorities
could potentially enhance the regulator framework. Note that this
integration introduces some implementation complexity, including wrapper
callbacks, but the potential benefits make it worthwhile.

Regulator are using enable counter with specific behavior.
Two calls to regulator_disable will trigger kernel warnings.
If the counter exceeds one, regulator_disable call won't disable the
PSE PI. These behavior isn't suitable for PSE control.
Added a boolean 'enabled' state to prevent multiple calls to
regulator_enable/disable. These calls will only be called from PSE
framework as it won't have any regulator children, therefore no mutex are
needed to safeguards this boolean.

regulator_get needs the consumer device pointer. Use PSE as regulator
provider and consumer device until we have RJ45 ports represented in
the Kernel.

Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20240417-feature_poe-v9-10-242293fd1900@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kmaincent

drivers/net/pse-pd/pse_core.c

@@ -8,6 +8,8 @@
 #include <linux/device.h>
 #include <linux/of.h>
 #include <linux/pse-pd/pse.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
 
 static DEFINE_MUTEX(pse_list_mutex);
 static LIST_HEAD(pse_controller_list);
@@ -16,12 +18,14 @@ static LIST_HEAD(pse_controller_list);
  * struct pse_control - a PSE control
  * @pcdev: a pointer to the PSE controller device
  *         this PSE control belongs to
+ * @ps: PSE PI supply of the PSE control
  * @list: list entry for the pcdev's PSE controller list
  * @id: ID of the PSE line in the PSE controller device
  * @refcnt: Number of gets of this pse_control
  */
 struct pse_control {
 	struct pse_controller_dev *pcdev;
+	struct regulator *ps;
 	struct list_head list;
 	unsigned int id;
 	struct kref refcnt;
@@ -132,19 +136,17 @@ static int of_load_pse_pis(struct pse_controller_dev *pcdev)
 	if (!np)
 		return -ENODEV;
 
+	pcdev->pi = kcalloc(pcdev->nr_lines, sizeof(*pcdev->pi), GFP_KERNEL);
+	if (!pcdev->pi)
+		return -ENOMEM;
+
 	pis = of_get_child_by_name(np, "pse-pis");
 	if (!pis) {
 		/* no description of PSE PIs */
 		pcdev->no_of_pse_pi = true;
 		return 0;
 	}
 
-	pcdev->pi = kcalloc(pcdev->nr_lines, sizeof(*pcdev->pi), GFP_KERNEL);
-	if (!pcdev->pi) {
-		of_node_put(pis);
-		return -ENOMEM;
-	}
-
 	for_each_child_of_node(pis, node) {
 		struct pse_pi pi = {0};
 		u32 id;
@@ -205,13 +207,124 @@ static int of_load_pse_pis(struct pse_controller_dev *pcdev)
 	return ret;
 }
 
+static int pse_pi_is_enabled(struct regulator_dev *rdev)
+{
+	struct pse_controller_dev *pcdev = rdev_get_drvdata(rdev);
+	const struct pse_controller_ops *ops;
+	int id, ret;
+
+	ops = pcdev->ops;
+	if (!ops->pi_is_enabled)
+		return -EOPNOTSUPP;
+
+	id = rdev_get_id(rdev);
+	mutex_lock(&pcdev->lock);
+	ret = ops->pi_is_enabled(pcdev, id);
+	mutex_unlock(&pcdev->lock);
+
+	return ret;
+}
+
+static int pse_pi_enable(struct regulator_dev *rdev)
+{
+	struct pse_controller_dev *pcdev = rdev_get_drvdata(rdev);
+	const struct pse_controller_ops *ops;
+	int id, ret;
+
+	ops = pcdev->ops;
+	if (!ops->pi_enable)
+		return -EOPNOTSUPP;
+
+	id = rdev_get_id(rdev);
+	mutex_lock(&pcdev->lock);
+	ret = ops->pi_enable(pcdev, id);
+	if (!ret)
+		pcdev->pi[id].admin_state_enabled = 1;
+	mutex_unlock(&pcdev->lock);
+
+	return ret;
+}
+
+static int pse_pi_disable(struct regulator_dev *rdev)
+{
+	struct pse_controller_dev *pcdev = rdev_get_drvdata(rdev);
+	const struct pse_controller_ops *ops;
+	int id, ret;
+
+	ops = pcdev->ops;
+	if (!ops->pi_disable)
+		return -EOPNOTSUPP;
+
+	id = rdev_get_id(rdev);
+	mutex_lock(&pcdev->lock);
+	ret = ops->pi_disable(pcdev, id);
+	if (!ret)
+		pcdev->pi[id].admin_state_enabled = 0;
+	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,
+};
+
+static int
+devm_pse_pi_regulator_register(struct pse_controller_dev *pcdev,
+			       char *name, int id)
+{
+	struct regulator_init_data *rinit_data;
+	struct regulator_config rconfig = {0};
+	struct regulator_desc *rdesc;
+	struct regulator_dev *rdev;
+
+	rinit_data = devm_kzalloc(pcdev->dev, sizeof(*rinit_data),
+				  GFP_KERNEL);
+	if (!rinit_data)
+		return -ENOMEM;
+
+	rdesc = devm_kzalloc(pcdev->dev, sizeof(*rdesc), GFP_KERNEL);
+	if (!rdesc)
+		return -ENOMEM;
+
+	/* Regulator descriptor id have to be the same as its associated
+	 * PSE PI id for the well functioning of the PSE controls.
+	 */
+	rdesc->id = id;
+	rdesc->name = name;
+	rdesc->type = REGULATOR_CURRENT;
+	rdesc->ops = &pse_pi_ops;
+	rdesc->owner = pcdev->owner;
+
+	rinit_data->constraints.valid_ops_mask = REGULATOR_CHANGE_STATUS;
+	rinit_data->supply_regulator = "vpwr";
+
+	rconfig.dev = pcdev->dev;
+	rconfig.driver_data = pcdev;
+	rconfig.init_data = rinit_data;
+
+	rdev = devm_regulator_register(pcdev->dev, rdesc, &rconfig);
+	if (IS_ERR(rdev)) {
+		dev_err_probe(pcdev->dev, PTR_ERR(rdev),
+			      "Failed to register regulator\n");
+		return PTR_ERR(rdev);
+	}
+
+	pcdev->pi[id].rdev = rdev;
+
+	return 0;
+}
+
 /**
  * pse_controller_register - register a PSE controller device
  * @pcdev: a pointer to the initialized PSE controller device
  */
 int pse_controller_register(struct pse_controller_dev *pcdev)
 {
-	int ret;
+	size_t reg_name_len;
+	int ret, i;
 
 	mutex_init(&pcdev->lock);
 	INIT_LIST_HEAD(&pcdev->pse_control_head);
@@ -229,6 +342,31 @@ int pse_controller_register(struct pse_controller_dev *pcdev)
 			return ret;
 	}
 
+	/* Each regulator name len is pcdev dev name + 7 char +
+	 * int max digit number (10) + 1
+	 */
+	reg_name_len = strlen(dev_name(pcdev->dev)) + 18;
+
+	/* Register PI regulators */
+	for (i = 0; i < pcdev->nr_lines; i++) {
+		char *reg_name;
+
+		/* Do not register regulator for PIs not described */
+		if (!pcdev->no_of_pse_pi && !pcdev->pi[i].np)
+			continue;
+
+		reg_name = devm_kzalloc(pcdev->dev, reg_name_len, GFP_KERNEL);
+		if (!reg_name)
+			return -ENOMEM;
+
+		snprintf(reg_name, reg_name_len, "pse-%s_pi%d",
+			 dev_name(pcdev->dev), i);
+
+		ret = devm_pse_pi_regulator_register(pcdev, reg_name, i);
+		if (ret)
+			return ret;
+	}
+
 	mutex_lock(&pse_list_mutex);
 	list_add(&pcdev->list, &pse_controller_list);
 	mutex_unlock(&pse_list_mutex);
@@ -297,6 +435,10 @@ static void __pse_control_release(struct kref *kref)
 
 	lockdep_assert_held(&pse_list_mutex);
 
+	if (psec->pcdev->pi[psec->id].admin_state_enabled)
+		regulator_disable(psec->ps);
+	devm_regulator_put(psec->ps);
+
 	module_put(psec->pcdev->owner);
 
 	list_del(&psec->list);
@@ -329,6 +471,7 @@ static struct pse_control *
 pse_control_get_internal(struct pse_controller_dev *pcdev, unsigned int index)
 {
 	struct pse_control *psec;
+	int ret;
 
 	lockdep_assert_held(&pse_list_mutex);
 
@@ -344,16 +487,38 @@ pse_control_get_internal(struct pse_controller_dev *pcdev, unsigned int index)
 		return ERR_PTR(-ENOMEM);
 
 	if (!try_module_get(pcdev->owner)) {
-		kfree(psec);
-		return ERR_PTR(-ENODEV);
+		ret = -ENODEV;
+		goto free_psec;
 	}
 
+	psec->ps = devm_regulator_get_exclusive(pcdev->dev,
+						rdev_get_name(pcdev->pi[index].rdev));
+	if (IS_ERR(psec->ps)) {
+		ret = PTR_ERR(psec->ps);
+		goto put_module;
+	}
+
+	ret = regulator_is_enabled(psec->ps);
+	if (ret < 0)
+		goto regulator_put;
+
+	pcdev->pi[index].admin_state_enabled = ret;
+
 	psec->pcdev = pcdev;
 	list_add(&psec->list, &pcdev->pse_control_head);
 	psec->id = index;
 	kref_init(&psec->refcnt);
 
 	return psec;
+
+regulator_put:
+	devm_regulator_put(psec->ps);
+put_module:
+	module_put(pcdev->owner);
+free_psec:
+	kfree(psec);
+
+	return ERR_PTR(ret);
 }
 
 /**
@@ -486,6 +651,54 @@ int pse_ethtool_get_status(struct pse_control *psec,
 }
 EXPORT_SYMBOL_GPL(pse_ethtool_get_status);
 
+static int pse_ethtool_c33_set_config(struct pse_control *psec,
+				      const struct pse_control_config *config)
+{
+	int err = 0;
+
+	/* Look at admin_state_enabled status to not call regulator_enable
+	 * or regulator_disable twice creating a regulator counter mismatch
+	 */
+	switch (config->c33_admin_control) {
+	case ETHTOOL_C33_PSE_ADMIN_STATE_ENABLED:
+		if (!psec->pcdev->pi[psec->id].admin_state_enabled)
+			err = regulator_enable(psec->ps);
+		break;
+	case ETHTOOL_C33_PSE_ADMIN_STATE_DISABLED:
+		if (psec->pcdev->pi[psec->id].admin_state_enabled)
+			err = regulator_disable(psec->ps);
+		break;
+	default:
+		err = -EOPNOTSUPP;
+	}
+
+	return err;
+}
+
+static int pse_ethtool_podl_set_config(struct pse_control *psec,
+				       const struct pse_control_config *config)
+{
+	int err = 0;
+
+	/* Look at admin_state_enabled status to not call regulator_enable
+	 * or regulator_disable twice creating a regulator counter mismatch
+	 */
+	switch (config->podl_admin_control) {
+	case ETHTOOL_PODL_PSE_ADMIN_STATE_ENABLED:
+		if (!psec->pcdev->pi[psec->id].admin_state_enabled)
+			err = regulator_enable(psec->ps);
+		break;
+	case ETHTOOL_PODL_PSE_ADMIN_STATE_DISABLED:
+		if (psec->pcdev->pi[psec->id].admin_state_enabled)
+			err = regulator_disable(psec->ps);
+		break;
+	default:
+		err = -EOPNOTSUPP;
+	}
+
+	return err;
+}
+
 /**
  * pse_ethtool_set_config - set PSE control configuration
  * @psec: PSE control pointer
@@ -496,20 +709,16 @@ int pse_ethtool_set_config(struct pse_control *psec,
 			   struct netlink_ext_ack *extack,
 			   const struct pse_control_config *config)
 {
-	const struct pse_controller_ops *ops;
-	int err;
-
-	ops = psec->pcdev->ops;
+	int err = 0;
 
-	if (!ops->ethtool_set_config) {
-		NL_SET_ERR_MSG(extack,
-			       "PSE driver does not configuration");
-		return -EOPNOTSUPP;
+	if (pse_has_c33(psec)) {
+		err = pse_ethtool_c33_set_config(psec, config);
+		if (err)
+			return err;
 	}
 
-	mutex_lock(&psec->pcdev->lock);
-	err = ops->ethtool_set_config(psec->pcdev, psec->id, extack, config);
-	mutex_unlock(&psec->pcdev->lock);
+	if (pse_has_podl(psec))
+		err = pse_ethtool_podl_set_config(psec, config);
 
 	return err;
 }