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

[Gupta, Akshay]

On 7/28/2025 12:07 PM, Thomas Weißschuh wrote:
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
>
>
> On 2025-07-28 06:10:30+0000, Akshay Gupta wrote:
> (...)
>
> > 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>
> Unnecessary include.
Ack, will remove. Thank you.
> > +#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>
> Ditto.
Ack, will remove.
> > +#include <linux/regmap.h>
> > +#include "rmi-core.h"
> > +
> > +static int sbrmi_enable_alert(struct sbrmi_data *data)
> > +{
> > +     int ctrl, ret;
> > +
> > +     /*
> > +      * Enable the SB-RMI Software alert status
> > +      * by writing 0 to bit 4 of Control register(0x1)
> > +      */
> > +     ret = regmap_read(data->regmap, SBRMI_CTRL, &ctrl);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     if (ctrl & 0x10) {
> Magic value? Use a define.
Ack, will create #define
> > +             ctrl &= ~0x10;
> > +             return regmap_write(data->regmap, SBRMI_CTRL, ctrl);
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static int sbrmi_get_max_pwr_limit(struct sbrmi_data *data)
> > +{
> > +     struct apml_mbox_msg msg = { 0 };
> > +     int ret;
> > +
> > +     msg.cmd = SBRMI_READ_PKG_MAX_PWR_LIMIT;
> > +     ret = rmi_mailbox_xfer(data, &msg);
> > +     if (ret < 0)
> > +             return ret;
> > +     data->pwr_limit_max = msg.mb_in_out;
> > +
> > +     return ret;
> > +}
> > +
> > +static int sbrmi_i3c_probe(struct i3c_device *i3cdev)
> > +{
> > +     struct device *dev = &i3cdev->dev;
> i3cdev_to_dev();
Ack, will update.
> > +     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);
> > +     if (!data)
> > +             return -ENOMEM;
> > +
> > +     mutex_init(&data->lock);
> devm_mutex_init().
Will address with new patch to use guard(mutex)
> > +
> > +     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);
> If you get rid of _remove(), then this can go away.
>
> > +
> > +     ret = create_hwmon_sensor_device(dev, data);
> That's a very generic name to have exported.
Will create separate patch to address this as this is used by i2c driver.
> > +     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);
> create_misc_rmi_device() could use devm_add_action_or_reset() for the
> misc deregister, simplifying the drivers code.
Ack , will update.
> > +     /* Assign fops and parent of misc dev to NULL */
> > +     data->sbrmi_misc_dev.fops = NULL;
> > +     data->sbrmi_misc_dev.parent = NULL;
> Why are these two needed? The data is freed anyways right after.
Ack, will update.
> > +     dev_info(&i3cdev->dev, "Removed sbrmi-i3c driver\n");
> Unnecessary.
Ack.
> > +}
> > +
> > +static const struct i3c_device_id sbrmi_i3c_id[] = {
> > +     /* PID for AMD SBRMI device */
> > +     I3C_DEVICE_EXTRA_INFO(0x112, 0x0, 0x2, NULL),
> > +     {}
> > +};
> > +MODULE_DEVICE_TABLE(i3c, sbrmi_i3c_id);
> > +
> > +static struct i3c_driver sbrmi_i3c_driver = {
> > +     .driver = {
> > +             .name = "sbrmi-i3c",
> > +     },
> > +     .probe = sbrmi_i3c_probe,
> > +     .remove = sbrmi_i3c_remove,
> > +     .id_table = sbrmi_i3c_id,
> > +};
> > +
> > +module_i3c_driver(sbrmi_i3c_driver);
> You could have the i2c and i3c drivers in the same module using
> module_i3c_i2c_driver().

Idea was to keep I2C and I3C separate as the drivers will become complex 
with

new platform specific changes related to register address size.

I will update the existing i2c driver for now.

> > +
> > +MODULE_IMPORT_NS("AMD_SBRMI");
> > +MODULE_AUTHOR("Akshay Gupta <akshay.gupta@xxxxxxx>");
> > +MODULE_AUTHOR("Naveen Krishna Chatradhi <naveenkrishna.chatradhi@xxxxxxx>");
> > +MODULE_DESCRIPTION("AMD SB-RMI driver over I3C");
> > +MODULE_LICENSE("GPL");
> > --
> > 2.25.1