[PATCH v5 3/5] mfd: p3h2x4x: Add driver for NXP P3H2x4x i3c hub and on-die regulator

[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.

This patch introduces the MFD driver that registers sub-devices for the
I3C hub and on-die regulators.

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

---
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         |  12 ++++
 drivers/mfd/Makefile        |   1 +
 drivers/mfd/p3h2840.c       | 128 ++++++++++++++++++++++++++++++++++++
 include/linux/mfd/p3h2840.h |  28 ++++++++
 5 files changed, 171 insertions(+)
 create mode 100644 drivers/mfd/p3h2840.c
 create mode 100644 include/linux/mfd/p3h2840.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 7e1a6cb22ca3..6c247e4a0c12 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18913,6 +18913,8 @@ 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 aace5766b38a..10d03cf308d7 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -606,6 +606,18 @@ 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
+       select MFD_CORE
+       select REGMAP_I3C
+       help
+         Enable Support for NXP P3H244x/P3H284x I3C HUB device using I3C/I2c
+         communication interface.
+
+         This driver provides support for I3C Hub and regulator, additional
+         drivers must be enabled in order to use the functionality of the device.
+
 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..aaadf50fedf4 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..acc10c396b47
--- /dev/null
+++ b/drivers/mfd/p3h2840.c
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2025 NXP
+ * P3H2x4x i3c hub and regulator device.
+ */
+
+#include <linux/i3c/master.h>
+#include <linux/i2c.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 I3C HUB regmap\n");
+	}
+
+	p3h2x4x->is_p3h2x4x_in_i3c = true;
+	p3h2x4x->i3cdev = i3cdev;
+
+	ret = devm_mfd_add_devices(&i3cdev->dev, PLATFORM_DEVID_NONE,
+				   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 I3C HUB regmap\n");
+	}
+
+	p3h2x4x->is_p3h2x4x_in_i3c = false;
+	p3h2x4x->i2c_client = client;
+
+	ret = devm_mfd_add_devices(&client->dev, PLATFORM_DEVID_NONE,
+				   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;
+}
+
+/* p3h2x4x ids (i3c) */
+static const struct i3c_device_id p3h2x4x_i3c_ids[] = {
+	I3C_CLASS(I3C_DCR_HUB, NULL),
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(i3c, p3h2x4x_i3c_ids);
+
+/* p3h2x4x ids (i2c) */
+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_DESCRIPTION("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..b7a9c7f3aa4d
--- /dev/null
+++ b/include/linux/mfd/p3h2840.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2025 NXP
+ * This header file contain private Reg address and its bit mapping etc.
+ */
+
+#ifndef P3H2840_H
+#define 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 i2c_client *i2c_client;
+	struct regmap *regmap;
+	bool is_p3h2x4x_in_i3c;
+};
+#endif /* P3H2840_H */
-- 
2.25.1