[PATCH v13 1/1] mux: Add driver for Renesas RZ/V2H VBENCTL VBUS_SEL mux

As per the RZ/V2H(P) HW manual, VBUSEN can be controlled by the VBUS_SEL
bit of the VBENCTL Control Register. This register is mapped in the
reset framework. The reset driver expose this register as mux-controller
and instantiates this driver. The consumer will use the mux API to
control the VBUS_SEL bit.

Reviewed-by: Lad Prabhakar <[email protected]>
Reviewed-by: Alvin Šipraga <[email protected]>
Reviewed-by: Philipp Zabel <[email protected]>
Signed-off-by: Tommaso Merciai <[email protected]>
---
v12->v13
 - Renamed CONFIG_MUX_RZV2H_USB_VBENCTL to CONFIG_MUX_RZV2H_VBENCTL and
   propagated the rename to the source file and module name.
 - Dropped the unneeded "depends on OF".
 - Added the missing "To compile the driver as a module" paragraph to the
   Kconfig help text.
 - Used the REG_FIELD() macro instead of open-coding struct reg_field, and
   made it const to keep checkpatch --strict without warning.
 - Used dev->parent instead of adev->dev.parent in dev_get_regmap().
 - Collected Reviewed-by tags from Alvin and Prabhakar (the changes above are
   cosmetic, please let me know if you want them dropped).

v11->v12
 - No changes, just rebased on top of next-20260714

v10->v11:
 - No changes.

v9->v10:
 - No changes.

v8->v9:
 - Fixed driver comment year (2025 -> 2026)
 - Switch from devm_regmap_init_mmio() to dev_get_regmap().
 - Drop unnecessasry include bitops.h, of.h, property.h and
   drivers/reset/reset-rzv2h-usb2phy.h headers, driver is now based on regmap.
 - Collected PZabel tag.

v7->v8:
 - No changes.

v6->v7:
 - No changes.

v5->v6:
 - No changes.

v4->v5:
 - Changed file name to rzv2h-usb-vbenctl.c and Fixed
   Makefile, Kconfig, function names accordingly.
 - Changed driver .name to "vbenctl" and fix auxiliary_device_id name.
 - Updated commit msg.

v3->v4:
 - Removed mux_chip->dev.of_node not needed.

v2->v3:
 - Added mux_chip->dev.of_node = dev->of_node->child as the mux-controller
   is an internal node.
 - Fixed auxiliary_device_id name.
 - Get rdev using from platform_data.
 - Drop struct auxiliary_device adev from reset_rzv2h_usb2phy_adev
   as it is needed.
 - Drop to_reset_rzv2h_usb2phy_adev() as it is not needed.

v1->v2:
 - New patch

 drivers/mux/Kconfig         | 13 ++++++
 drivers/mux/Makefile        |  2 +
 drivers/mux/rzv2h-vbenctl.c | 81 +++++++++++++++++++++++++++++++++++++
 3 files changed, 96 insertions(+)
 create mode 100644 drivers/mux/rzv2h-vbenctl.c

diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
index 6d17dfa25dad..eb34457beaab 100644
--- a/drivers/mux/Kconfig
+++ b/drivers/mux/Kconfig
@@ -70,6 +70,19 @@ config MUX_MMIO
 	  To compile the driver as a module, choose M here: the module will
 	  be called mux-mmio.
 
+config MUX_RZV2H_VBENCTL
+	tristate "Renesas RZ/V2H VBENCTL VBUS_SEL mux driver"
+	depends on RESET_RZV2H_USB2PHY || COMPILE_TEST
+	select REGMAP
+	select AUXILIARY_BUS
+	default RESET_RZV2H_USB2PHY
+	help
+	  Support for the VBENCTL VBUS_SEL mux implemented on Renesas
+	  RZ/V2H SoCs.
+
+	  To compile the driver as a module, choose M here: the module will
+	  be called mux-rzv2h-vbenctl.
+
 endmenu
 
 endif # MULTIPLEXER
diff --git a/drivers/mux/Makefile b/drivers/mux/Makefile
index 6e9fa47daf56..0854c04613b9 100644
--- a/drivers/mux/Makefile
+++ b/drivers/mux/Makefile
@@ -8,9 +8,11 @@ mux-adg792a-objs		:= adg792a.o
 mux-adgs1408-objs		:= adgs1408.o
 mux-gpio-objs			:= gpio.o
 mux-mmio-objs			:= mmio.o
+mux-rzv2h-vbenctl-objs		:= rzv2h-vbenctl.o
 
 obj-$(CONFIG_MULTIPLEXER)	+= mux-core.o
 obj-$(CONFIG_MUX_ADG792A)	+= mux-adg792a.o
 obj-$(CONFIG_MUX_ADGS1408)	+= mux-adgs1408.o
 obj-$(CONFIG_MUX_GPIO)		+= mux-gpio.o
 obj-$(CONFIG_MUX_MMIO)		+= mux-mmio.o
+obj-$(CONFIG_MUX_RZV2H_VBENCTL)	+= mux-rzv2h-vbenctl.o
diff --git a/drivers/mux/rzv2h-vbenctl.c b/drivers/mux/rzv2h-vbenctl.c
new file mode 100644
index 000000000000..2699458045f3
--- /dev/null
+++ b/drivers/mux/rzv2h-vbenctl.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Renesas RZ/V2H(P) VBENCTL VBUS_SEL mux driver
+ *
+ * Copyright (C) 2026 Renesas Electronics Corp.
+ */
+
+#include <linux/auxiliary_bus.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/mux/driver.h>
+#include <linux/regmap.h>
+
+#define RZV2H_VBENCTL		0xf0c
+
+struct mux_rzv2h_vbenctl_priv {
+	struct regmap_field *field;
+};
+
+static int mux_rzv2h_vbenctl_set(struct mux_control *mux, int state)
+{
+	struct mux_rzv2h_vbenctl_priv *priv = mux_chip_priv(mux->chip);
+
+	return regmap_field_write(priv->field, state);
+}
+
+static const struct mux_control_ops mux_rzv2h_vbenctl_ops = {
+	.set = mux_rzv2h_vbenctl_set,
+};
+
+static int mux_rzv2h_vbenctl_probe(struct auxiliary_device *adev,
+				   const struct auxiliary_device_id *id)
+{
+	const struct reg_field reg_field = REG_FIELD(RZV2H_VBENCTL, 0, 0);
+	struct mux_rzv2h_vbenctl_priv *priv;
+	struct device *dev = &adev->dev;
+	struct mux_chip *mux_chip;
+	struct regmap *regmap;
+	int ret;
+
+	regmap = dev_get_regmap(dev->parent, NULL);
+	if (!regmap)
+		return -ENODEV;
+
+	mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*priv));
+	if (IS_ERR(mux_chip))
+		return PTR_ERR(mux_chip);
+
+	priv = mux_chip_priv(mux_chip);
+
+	priv->field = devm_regmap_field_alloc(dev, regmap, reg_field);
+	if (IS_ERR(priv->field))
+		return PTR_ERR(priv->field);
+
+	mux_chip->ops = &mux_rzv2h_vbenctl_ops;
+	mux_chip->mux[0].states = 2;
+	mux_chip->mux[0].idle_state = MUX_IDLE_AS_IS;
+
+	ret = devm_mux_chip_register(dev, mux_chip);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to register mux chip\n");
+
+	return 0;
+}
+
+static const struct auxiliary_device_id mux_rzv2h_vbenctl_ids[] = {
+	{ .name = "rzv2h_usb2phy_reset.vbenctl" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(auxiliary, mux_rzv2h_vbenctl_ids);
+
+static struct auxiliary_driver mux_rzv2h_vbenctl_driver = {
+	.name		= "vbenctl",
+	.probe		= mux_rzv2h_vbenctl_probe,
+	.id_table	= mux_rzv2h_vbenctl_ids,
+};
+module_auxiliary_driver(mux_rzv2h_vbenctl_driver);
+
+MODULE_DESCRIPTION("RZ/V2H VBENCTL VBUS_SEL mux driver");
+MODULE_AUTHOR("Tommaso Merciai <[email protected]>");
+MODULE_LICENSE("GPL");
-- 
2.54.0