regulator: Add Renesas RZ/G2L USB VBUS regulator driver

As per the RZ/G2L HW manual, VBUSEN can be controlled by the VBOUT
bit of the VBUS Control Register. This register is mapped in the reset
framework. The reset driver expose this register as regmap and instantiates
this driver. The consumer will use the regulator API to control the VBOUT
bit as the control need to be done in the atomic context.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://patch.msgid.link/20240616105402.45211-5-biju.das.jz@bp.renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: bijudas

drivers/regulator/Kconfig

@@ -1634,6 +1634,15 @@ config REGULATOR_UNIPHIER
 	help
 	  Support for regulators implemented on Socionext UniPhier SoCs.
 
+config REGULATOR_RZG2L_VBCTRL
+	tristate "Renesas RZ/G2L USB VBUS regulator driver"
+	depends on ARCH_RZG2L || COMPILE_TEST
+	depends on OF
+	select REGMAP_MMIO
+	default ARCH_RZG2L
+	help
+	  Support for VBUS regulators implemented on Renesas RZ/G2L SoCs.
+
 config REGULATOR_VCTRL
 	tristate "Voltage controlled regulators"
 	depends on OF

drivers/regulator/Makefile

@@ -189,6 +189,7 @@ obj-$(CONFIG_REGULATOR_TPS65132) += tps65132-regulator.o
 obj-$(CONFIG_REGULATOR_TPS68470) += tps68470-regulator.o
 obj-$(CONFIG_REGULATOR_TWL4030) += twl-regulator.o twl6030-regulator.o
 obj-$(CONFIG_REGULATOR_UNIPHIER) += uniphier-regulator.o
+obj-$(CONFIG_REGULATOR_RZG2L_VBCTRL) += renesas-usb-vbus-regulator.o
 obj-$(CONFIG_REGULATOR_VCTRL) += vctrl-regulator.o
 obj-$(CONFIG_REGULATOR_VEXPRESS) += vexpress-regulator.o
 obj-$(CONFIG_REGULATOR_VQMMC_IPQ4019) += vqmmc-ipq4019-regulator.o

drivers/regulator/renesas-usb-vbus-regulator.c

@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Renesas USB VBUS output regulator driver
+//
+// Copyright (C) 2024 Renesas Electronics Corporation
+//
+
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/of_regulator.h>
+
+static const struct regulator_ops rzg2l_usb_vbus_reg_ops = {
+	.enable     = regulator_enable_regmap,
+	.disable    = regulator_disable_regmap,
+	.is_enabled = regulator_is_enabled_regmap,
+};
+
+static const struct regulator_desc rzg2l_usb_vbus_rdesc = {
+	.name = "vbus",
+	.of_match = of_match_ptr("regulator-vbus"),
+	.ops = &rzg2l_usb_vbus_reg_ops,
+	.type = REGULATOR_VOLTAGE,
+	.owner = THIS_MODULE,
+	.enable_reg  = 0,
+	.enable_mask = BIT(0),
+	.enable_is_inverted = true,
+	.fixed_uV	= 5000000,
+	.n_voltages	= 1,
+};
+
+static int rzg2l_usb_vbus_regulator_probe(struct platform_device *pdev)
+{
+	struct regulator_config config = { };
+	struct device *dev = &pdev->dev;
+	struct regulator_dev *rdev;
+
+	config.regmap = dev_get_regmap(dev->parent, NULL);
+	if (!config.regmap)
+		return dev_err_probe(dev, -ENOENT, "Failed to get regmap\n");
+
+	config.dev = dev;
+	config.of_node = of_get_child_by_name(dev->parent->of_node, "regulator-vbus");
+	if (!config.of_node)
+		return dev_err_probe(dev, -ENODEV, "regulator node not found\n");
+
+	rdev = devm_regulator_register(dev, &rzg2l_usb_vbus_rdesc, &config);
+	if (IS_ERR(rdev)) {
+		of_node_put(config.of_node);
+		return dev_err_probe(dev, PTR_ERR(rdev),
+				     "not able to register vbus regulator\n");
+	}
+
+	of_node_put(config.of_node);
+
+	return 0;
+}
+
+static struct platform_driver rzg2l_usb_vbus_regulator_driver = {
+	.probe = rzg2l_usb_vbus_regulator_probe,
+	.driver	= {
+		.name = "rzg2l-usb-vbus-regulator",
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+};
+module_platform_driver(rzg2l_usb_vbus_regulator_driver);
+
+MODULE_AUTHOR("Biju Das <biju.das.jz@bp.renesas.com>");
+MODULE_DESCRIPTION("Renesas RZ/G2L USB Vbus Regulator Driver");
+MODULE_LICENSE("GPL");