net: pse-pd: add regulator based PSE driver

Add generic, regulator based PSE driver to support simple Power Sourcing
Equipment without automatic classification support.

This driver was tested on 10Bast-T1L switch with regulator based PoDL PSE.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/pse-pd/Kconfig

@@ -9,3 +9,14 @@ menuconfig PSE_CONTROLLER
 	  Generic Power Sourcing Equipment Controller support.
 
 	  If unsure, say no.
+
+if PSE_CONTROLLER
+
+config PSE_REGULATOR
+	tristate "Regulator based PSE controller"
+	help
+	  This module provides support for simple regulator based Ethernet Power
+	  Sourcing Equipment without automatic classification support. For
+	  example for basic implementation of PoDL (802.3bu) specification.
+
+endif

drivers/net/pse-pd/Makefile

@@ -2,3 +2,5 @@
 # Makefile for Linux PSE drivers
 
 obj-$(CONFIG_PSE_CONTROLLER) += pse_core.o
+
+obj-$(CONFIG_PSE_REGULATOR) += pse_regulator.o

drivers/net/pse-pd/pse_regulator.c

+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Driver for the regulator based Ethernet Power Sourcing Equipment, without
+// auto classification support.
+//
+// Copyright (c) 2022 Pengutronix, Oleksij Rempel <kernel@pengutronix.de>
+//
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pse-pd/pse.h>
+#include <linux/regulator/consumer.h>
+
+struct pse_reg_priv {
+	struct pse_controller_dev pcdev;
+	struct regulator *ps; /*power source */
+	enum ethtool_podl_pse_admin_state admin_state;
+};
+
+static struct pse_reg_priv *to_pse_reg(struct pse_controller_dev *pcdev)
+{
+	return container_of(pcdev, struct pse_reg_priv, pcdev);
+}
+
+static int
+pse_reg_ethtool_set_config(struct pse_controller_dev *pcdev, unsigned long id,
+			   struct netlink_ext_ack *extack,
+			   const struct pse_control_config *config)
+{
+	struct pse_reg_priv *priv = to_pse_reg(pcdev);
+	int ret;
+
+	if (priv->admin_state == config->admin_cotrol)
+		return 0;
+
+	switch (config->admin_cotrol) {
+	case ETHTOOL_PODL_PSE_ADMIN_STATE_ENABLED:
+		ret = regulator_enable(priv->ps);
+		break;
+	case ETHTOOL_PODL_PSE_ADMIN_STATE_DISABLED:
+		ret = regulator_disable(priv->ps);
+		break;
+	default:
+		dev_err(pcdev->dev, "Unknown admin state %i\n",
+			config->admin_cotrol);
+		ret = -ENOTSUPP;
+	}
+
+	if (ret)
+		return ret;
+
+	priv->admin_state = config->admin_cotrol;
+
+	return 0;
+}
+
+static int
+pse_reg_ethtool_get_status(struct pse_controller_dev *pcdev, unsigned long id,
+			   struct netlink_ext_ack *extack,
+			   struct pse_control_status *status)
+{
+	struct pse_reg_priv *priv = to_pse_reg(pcdev);
+	int ret;
+
+	ret = regulator_is_enabled(priv->ps);
+	if (ret < 0)
+		return ret;
+
+	if (!ret)
+		status->podl_pw_status = ETHTOOL_PODL_PSE_PW_D_STATUS_DISABLED;
+	else
+		status->podl_pw_status =
+			ETHTOOL_PODL_PSE_PW_D_STATUS_DELIVERING;
+
+	status->podl_admin_state = priv->admin_state;
+
+	return 0;
+}
+
+static const struct pse_controller_ops pse_reg_ops = {
+	.ethtool_get_status = pse_reg_ethtool_get_status,
+	.ethtool_set_config = pse_reg_ethtool_set_config,
+};
+
+static int
+pse_reg_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct pse_reg_priv *priv;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	if (!pdev->dev.of_node)
+		return -ENOENT;
+
+	priv->ps = devm_regulator_get_exclusive(dev, "pse");
+	if (IS_ERR(priv->ps))
+		return dev_err_probe(dev, PTR_ERR(priv->ps),
+				     "failed to get PSE regulator.\n");
+
+	platform_set_drvdata(pdev, priv);
+
+	ret = regulator_is_enabled(priv->ps);
+	if (ret < 0)
+		return ret;
+
+	if (ret)
+		priv->admin_state = ETHTOOL_PODL_PSE_ADMIN_STATE_ENABLED;
+	else
+		priv->admin_state = ETHTOOL_PODL_PSE_ADMIN_STATE_DISABLED;
+
+	priv->pcdev.owner = THIS_MODULE;
+	priv->pcdev.ops = &pse_reg_ops;
+	priv->pcdev.dev = dev;
+	ret = devm_pse_controller_register(dev, &priv->pcdev);
+	if (ret) {
+		dev_err(dev, "failed to register PSE controller (%pe)\n",
+			ERR_PTR(ret));
+		return ret;
+	}
+
+	return 0;
+}
+
+static const __maybe_unused struct of_device_id pse_reg_of_match[] = {
+	{ .compatible = "podl-pse-regulator", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, pse_reg_of_match);
+
+static struct platform_driver pse_reg_driver = {
+	.probe		= pse_reg_probe,
+	.driver		= {
+		.name		= "PSE regulator",
+		.of_match_table = of_match_ptr(pse_reg_of_match),
+	},
+};
+module_platform_driver(pse_reg_driver);
+
+MODULE_AUTHOR("Oleksij Rempel <kernel@pengutronix.de>");
+MODULE_DESCRIPTION("regulator based Ethernet Power Sourcing Equipment");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:pse-regulator");