Re: [PATCH v6 4/7] mfd: p3h2x4x: Add driver for NXP P3H2x4x i3c hub and on-die regulator

Jorge Marques
2026-03-10T09:08:18Z

On Tue, Mar 10, 2026 at 12:27:24PM +0530, Lakshay Piplani wrote:
> 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>
>
> ---
> 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 | 12 ++++
> drivers/mfd/Makefile | 1 +
> drivers/mfd/p3h2840.c | 126 ++++++++++++++++++++++++++++++++++++
> include/linux/mfd/p3h2840.h | 28 ++++++++
> 5 files changed, 169 insertions(+)
> create mode 100644 drivers/mfd/p3h2840.c
> create mode 100644 include/linux/mfd/p3h2840.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 06b803d6f45d..cc33c6c300e4 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -19114,6 +19114,8 @@ 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..645a8e4e62b6 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -617,6 +617,18 @@ 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.
> +
Hi Aman, our CI/CD is failing with

arm-linux-ld: drivers/mfd/p3h2840.o: in function `p3h2x4x_device_probe_i2c':
P3h2840.c:(.text+0x40): undefined reference to `__devm_regmap_init_i2c'

And indeed

$ find . -name 'regmap*.o'
./drivers/base/regmap/regmap.o
./drivers/base/regmap/regmap-i3c.o

It infers the systems based on the KConfig+Makefile
I suggest adding select REGMAP_I2C, since your driver does call i2c
regmap methods (line 67), outside the regmap i3c umbrella.

Also, which drivers must be enabled to use the functionality?

Thanks,
Jorge

> 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..774fbb67b025
> --- /dev/null
> +++ b/drivers/mfd/p3h2840.c
> @@ -0,0 +1,126 @@
> +// 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..9ed2a0d0564e
> --- /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 _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 i2c_client *i2c_client;
> + struct regmap *regmap;
> + bool is_p3h2x4x_in_i3c;
> +};
> +#endif /* _LINUX_MFD_P3H2840_H */
> --
> 2.25.1