Re: [PATCH v1 2/5] misc: amd-sbi: Add support for SB-RMI over I3C

[Gupta, Akshay]

On 7/29/2025 12:03 PM, Krzysztof Kozlowski wrote:
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
>
>
> On 28/07/2025 08:10, Akshay Gupta wrote:
> > AMD EPYC platforms with zen5 and later support APML(SB-RMI)
> > connection to the BMC over I3C bus for improved efficiency.
> > Add the same functionality supported by rmi-i2c.c over I3C bus.
> >
> > Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@xxxxxxx>
> > Signed-off-by: Akshay Gupta <akshay.gupta@xxxxxxx>
> > ---
> >   drivers/misc/amd-sbi/Kconfig   |  15 +++-
> >   drivers/misc/amd-sbi/Makefile  |   2 +
> >   drivers/misc/amd-sbi/rmi-i3c.c | 133 +++++++++++++++++++++++++++++++++
> >   3 files changed, 148 insertions(+), 2 deletions(-)
> >   create mode 100644 drivers/misc/amd-sbi/rmi-i3c.c
> >
> > diff --git a/drivers/misc/amd-sbi/Kconfig b/drivers/misc/amd-sbi/Kconfig
> > index 9b1abeb6ab1a..838cf98805d9 100644
> > --- a/drivers/misc/amd-sbi/Kconfig
> > +++ b/drivers/misc/amd-sbi/Kconfig
> > @@ -15,10 +15,21 @@ config AMD_SBRMI_I2C
> >          This driver can also be built as a module. If so, the module will
> >          be called sbrmi-i2c.
> >
> > +config AMD_SBRMI_I3C
> > +     tristate "AMD side band RMI support over I3C"
> > +     depends on I3C
> > +     select AMD_SBRMI
> > +     select REGMAP_I3C
> > +     help
> > +       Side band RMI over I3C support for AMD out of band management.
> > +
> > +       This driver can also be built as a module. If so, the module will
> > +       be called sbrmi-i3c.
> > +
> >   config AMD_SBRMI_HWMON
> >        bool "SBRMI hardware monitoring"
> > -     depends on AMD_SBRMI_I2C && HWMON
> > -     depends on !(AMD_SBRMI_I2C=y && HWMON=m)
> > +     depends on (AMD_SBRMI_I2C || AMD_SBRMI_I3C) && HWMON
> > +     depends on !(AMD_SBRMI_I2C=y && HWMON=m) || !(AMD_SBRMI_I3C=y && HWMON=m)
> >        help
> >          This provides support for RMI device hardware monitoring. If enabled,
> >          a hardware monitoring device will be created for each socket in
> > diff --git a/drivers/misc/amd-sbi/Makefile b/drivers/misc/amd-sbi/Makefile
> > index 6f3090fb9ff3..e43d4058a0f0 100644
> > --- a/drivers/misc/amd-sbi/Makefile
> > +++ b/drivers/misc/amd-sbi/Makefile
> > @@ -4,3 +4,5 @@ sbrmi_core-y                  := rmi-core.o
> >   obj-$(CONFIG_AMD_SBRMI_HWMON)        += rmi-hwmon.o
> >   sbrmi-i2c-y                  := rmi-i2c.o
> >   obj-$(CONFIG_AMD_SBRMI_I2C)  += sbrmi-i2c.o
> > +sbrmi-i3c-y                          := rmi-i3c.o
> > +obj-$(CONFIG_AMD_SBRMI_I3C)  += sbrmi-i3c.o
> > diff --git a/drivers/misc/amd-sbi/rmi-i3c.c b/drivers/misc/amd-sbi/rmi-i3c.c
> > new file mode 100644
> > index 000000000000..b960743afad1
> > --- /dev/null
> > +++ b/drivers/misc/amd-sbi/rmi-i3c.c
> > @@ -0,0 +1,133 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/*
> > + * rmi-i3c.c - Side band RMI over I3C support for AMD out
> > + *             of band management
> > + *
> > + * Copyright (C) 2025 Advanced Micro Devices, Inc.
> > + */
> > +
> > +#include <linux/delay.h>
> > +#include <linux/err.h>
> > +#include <linux/i3c/device.h>
> > +#include <linux/i3c/master.h>
> > +#include <linux/init.h>
> > +#include <linux/module.h>
> > +#include <linux/mutex.h>
> > +#include <linux/of.h>
> Where do you use it?
Ack, will remove.
> > +#include <linux/regmap.h>
> > +#include "rmi-core.h"
>
> ...
>
> > +static int sbrmi_i3c_probe(struct i3c_device *i3cdev)
> > +{
> > +     struct device *dev = &i3cdev->dev;
> > +     struct sbrmi_data *data;
> > +     struct regmap_config sbrmi_i3c_regmap_config = {
> > +             .reg_bits = 8,
> > +             .val_bits = 8,
> > +     };
> > +     int ret;
> > +
> > +     data = devm_kzalloc(dev, sizeof(struct sbrmi_data), GFP_KERNEL);
> sizeof(*). Use recent coding style, not some old, downstream code.
Ack, will update.
> > +     if (!data)
> > +             return -ENOMEM;
> > +
> > +     mutex_init(&data->lock);
> > +
> > +     data->regmap = devm_regmap_init_i3c(i3cdev, &sbrmi_i3c_regmap_config);
> > +     if (IS_ERR(data->regmap))
> > +             return PTR_ERR(data->regmap);
> > +
> > +     /* Enable alert for SB-RMI sequence */
> > +     ret = sbrmi_enable_alert(data);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     /* Cache maximum power limit */
> > +     ret = sbrmi_get_max_pwr_limit(data);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     /*
> > +      * AMD APML I3C devices support static address
> > +      */
> > +     if (i3cdev->desc->info.static_addr)
> > +             data->dev_static_addr = i3cdev->desc->info.static_addr;
> > +     else
> > +             data->dev_static_addr = i3cdev->desc->info.dyn_addr;
> > +
> > +     dev_set_drvdata(dev, data);
> > +
> > +     ret = create_hwmon_sensor_device(dev, data);
> > +     if (ret < 0)
> > +             return ret;
> > +     return create_misc_rmi_device(data, dev);
> > +}
> > +
> > +static void sbrmi_i3c_remove(struct i3c_device *i3cdev)
> > +{
> > +     struct sbrmi_data *data = dev_get_drvdata(&i3cdev->dev);
> > +
> > +     misc_deregister(&data->sbrmi_misc_dev);
> > +     /* Assign fops and parent of misc dev to NULL */
> > +     data->sbrmi_misc_dev.fops = NULL;
> > +     data->sbrmi_misc_dev.parent = NULL;
> > +     dev_info(&i3cdev->dev, "Removed sbrmi-i3c driver\n");
> No, drop. This is useless.
Ack, will update.
> Best regards,
> Krzysztof