[PATCH v9 4/7] mfd: p3h2x4x: Add driver for NXP P3H2x4x i3c hub and on-die regulator

[Lakshay Piplani <lakshay.piplani@nxp.com>]

From: Aman Kumar Pandey <aman.kumarpandey@nxp.com>

Add core MFD support for the NXP P3H2x4x (P3H2440/P3H2441/P3H2840/P3H2841)
family of multiport I3C hub devices. These devices connect to a host via
I3C/I2C/SMBus and expose multiple downstream target ports.

Signed-off-by: Aman Kumar Pandey <aman.kumarpandey@nxp.com>
Signed-off-by: Vikash Bansal <vikash.bansal@nxp.com>
Signed-off-by: Lakshay Piplani <lakshay.piplani@nxp.com>

---
Changes in v9:
 - Renamed macros to follow consistent uppercase naming conventions
 - Made REGMAP selects in the P3H2X4X MFD Kconfig conditional,
   to avoid I3C/I2C dependency issues

Changes in v8:
 - No change

Changes in v7:
 - Use new config I3C_OR_I2C

Changes in v6:
 - No change

Changes in v5:
 - Corrected the ordering in the Makefile and Kconfig for MFD_P3H2X4X
 - Updated dev_err_probe() for regmap_init failure.
 - Updated module description

Changes in v4:
 - Split the driver into three separate patches(mfd, regulator and I3C hub)
 - Added support for NXP P3H2x4x MFD functionality
---
---
 MAINTAINERS                 |   2 +
 drivers/mfd/Kconfig         |  13 ++++
 drivers/mfd/Makefile        |   1 +
 drivers/mfd/p3h2840.c       | 124 ++++++++++++++++++++++++++++++++++++
 include/linux/mfd/p3h2840.h |  27 ++++++++
 5 files changed, 167 insertions(+)
 create mode 100644 drivers/mfd/p3h2840.c
 create mode 100644 include/linux/mfd/p3h2840.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 4425816b478b..a2c2f7d944b0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19274,6 +19274,8 @@ L:	linux-kernel@vger.kernel.org
 L:	linux-i3c-owner@lists.infradead.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/i3c/nxp,p3h2840.yaml
+F:	drivers/mfd/p3h2840.c
+F:	include/linux/mfd/p3h2840.h
 
 NXP PF5300/PF5301/PF5302 PMIC REGULATOR DEVICE DRIVER
 M:	Woodrow Douglass <wdouglass@carnegierobotics.com>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 7192c9d1d268..405b50c3c77b 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -617,6 +617,19 @@ config MFD_MX25_TSADC
 	  i.MX25 processors. They consist of a conversion queue for general
 	  purpose ADC and a queue for Touchscreens.
 
+config MFD_P3H2X4X
+	tristate "NXP P3H2X4X I3C Hub Device"
+	depends on I3C_OR_I2C
+	select MFD_CORE
+	select REGMAP_I3C if I3C
+	select REGMAP_I2C if I2C
+	help
+	  Enable Support for NXP P3H244x/P3H284x I3C HUB device using I3C/I2C
+	  communication interface.
+
+	  This driver provides support for I3C hub and regulator, each subdriver
+	  can be enabled independently depending on the required functionality.
+
 config MFD_PF1550
 	tristate "NXP PF1550 PMIC Support"
 	depends on I2C=y && OF
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index e75e8045c28a..a284b22c7b13 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -122,6 +122,7 @@ obj-$(CONFIG_MFD_MC13XXX)	+= mc13xxx-core.o
 obj-$(CONFIG_MFD_MC13XXX_SPI)	+= mc13xxx-spi.o
 obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
 
+obj-$(CONFIG_MFD_P3H2X4X)	+= p3h2840.o
 obj-$(CONFIG_MFD_PF1550)	+= pf1550.o
 
 obj-$(CONFIG_MFD_NCT6694)	+= nct6694.o
diff --git a/drivers/mfd/p3h2840.c b/drivers/mfd/p3h2840.c
new file mode 100644
index 000000000000..14c0b0f142ef
--- /dev/null
+++ b/drivers/mfd/p3h2840.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2025-2026 NXP
+ * P3H2X4X i3c hub and regulator device.
+ */
+
+#include <linux/i2c.h>
+#include <linux/i3c/master.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/p3h2840.h>
+#include <linux/regmap.h>
+
+static const struct mfd_cell p3h2x4x_devs[] = {
+	{
+		.name = "p3h2x4x-regulator",
+	},
+	{
+		.name = "p3h2x4x-i3c-hub",
+	},
+};
+
+static const struct regmap_config p3h2x4x_regmap_config = {
+	.reg_bits = P3H2X4X_REG_BITS,
+	.val_bits = P3H2X4X_VAL_BITS,
+	.max_register = 0xFF,
+};
+
+static int p3h2x4x_device_probe_i3c(struct i3c_device *i3cdev)
+{
+	struct p3h2x4x_dev *p3h2x4x;
+	int ret;
+
+	p3h2x4x = devm_kzalloc(&i3cdev->dev, sizeof(*p3h2x4x), GFP_KERNEL);
+	if (!p3h2x4x)
+		return -ENOMEM;
+
+	i3cdev_set_drvdata(i3cdev, p3h2x4x);
+
+	p3h2x4x->regmap = devm_regmap_init_i3c(i3cdev, &p3h2x4x_regmap_config);
+	if (IS_ERR(p3h2x4x->regmap))
+		return dev_err_probe(&i3cdev->dev, PTR_ERR(p3h2x4x->regmap),
+				     "Failed to register HUB regmap\n");
+
+	p3h2x4x->is_p3h2x4x_in_i3c = true;
+	p3h2x4x->i3cdev = i3cdev;
+
+	ret = devm_mfd_add_devices(&i3cdev->dev, PLATFORM_DEVID_AUTO,
+				   p3h2x4x_devs, ARRAY_SIZE(p3h2x4x_devs),
+				   NULL, 0, NULL);
+	if (ret)
+		return dev_err_probe(&i3cdev->dev, ret, "Failed to add sub devices\n");
+
+	return 0;
+}
+
+static int p3h2x4x_device_probe_i2c(struct i2c_client *client)
+{
+	struct p3h2x4x_dev *p3h2x4x;
+	int ret;
+
+	p3h2x4x = devm_kzalloc(&client->dev, sizeof(*p3h2x4x), GFP_KERNEL);
+	if (!p3h2x4x)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, p3h2x4x);
+
+	p3h2x4x->regmap = devm_regmap_init_i2c(client, &p3h2x4x_regmap_config);
+	if (IS_ERR(p3h2x4x->regmap))
+		return dev_err_probe(&client->dev, PTR_ERR(p3h2x4x->regmap),
+				     "Failed to register HUB regmap\n");
+
+	p3h2x4x->is_p3h2x4x_in_i3c = false;
+
+	ret = devm_mfd_add_devices(&client->dev, PLATFORM_DEVID_AUTO,
+				   p3h2x4x_devs, ARRAY_SIZE(p3h2x4x_devs),
+				   NULL, 0, NULL);
+	if (ret)
+		return dev_err_probe(&client->dev, ret, "Failed to add sub devices\n");
+
+	return 0;
+}
+
+static const struct i3c_device_id p3h2x4x_i3c_ids[] = {
+	I3C_CLASS(I3C_DCR_HUB, NULL),
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(i3c, p3h2x4x_i3c_ids);
+
+static const struct i2c_device_id p3h2x4x_i2c_id_table[] = {
+	{ "nxp-i3c-hub" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(i2c, p3h2x4x_i2c_id_table);
+
+static const struct of_device_id p3h2x4x_i2c_of_match[] = {
+	{ .compatible = "nxp,p3h2840", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, p3h2x4x_i2c_of_match);
+
+static struct i3c_driver p3h2x4x_i3c = {
+	.driver = {
+		.name = "p3h2x4x_i3c_drv",
+	},
+	.probe = p3h2x4x_device_probe_i3c,
+	.id_table = p3h2x4x_i3c_ids,
+};
+
+static struct i2c_driver p3h2x4x_i2c = {
+	.driver = {
+		.name = "p3h2x4x_i2c_drv",
+		.of_match_table = p3h2x4x_i2c_of_match,
+	},
+	.probe =  p3h2x4x_device_probe_i2c,
+	.id_table = p3h2x4x_i2c_id_table,
+};
+
+module_i3c_i2c_driver(p3h2x4x_i3c, &p3h2x4x_i2c);
+
+MODULE_AUTHOR("Aman Kumar Pandey <aman.kumarpandey@nxp.com>");
+MODULE_AUTHOR("Vikash Bansal <vikash.bansal@nxp.com>");
+MODULE_AUTHOR("Lakshay Piplani <lakshay.piplani@nxp.com>");
+MODULE_DESCRIPTION("NXP P3H2X4X I3C HUB multi function driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/mfd/p3h2840.h b/include/linux/mfd/p3h2840.h
new file mode 100644
index 000000000000..7ffaf1778f71
--- /dev/null
+++ b/include/linux/mfd/p3h2840.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2025-2026 NXP
+ * This header file contain private Reg address and its bit mapping etc.
+ */
+
+#ifndef _LINUX_MFD_P3H2840_H
+#define _LINUX_MFD_P3H2840_H
+
+#include <linux/types.h>
+
+/* Device Configuration Registers */
+#define P3H2X4X_DEV_REG_PROTECTION_CODE				0x10
+#define P3H2X4X_REGISTERS_LOCK_CODE				0x00
+#define P3H2X4X_REGISTERS_UNLOCK_CODE				0x69
+#define P3H2X4X_CP1_REGISTERS_UNLOCK_CODE			0x6a
+
+/* Reg config for Regmap */
+#define P3H2X4X_REG_BITS					8
+#define P3H2X4X_VAL_BITS					8
+
+struct p3h2x4x_dev {
+	struct i3c_device *i3cdev;
+	struct regmap *regmap;
+	bool is_p3h2x4x_in_i3c;
+};
+#endif /* _LINUX_MFD_P3H2840_H */
-- 
2.25.1