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Message-ID: <20250728061033.1604169-2-akshay.gupta@amd.com>
Date: Mon, 28 Jul 2025 06:10:30 +0000
From: Akshay Gupta <akshay.gupta@....com>
To: <linux-kernel@...r.kernel.org>, <linux-hwmon@...r.kernel.org>
CC: <gregkh@...uxfoundation.org>, <arnd@...db.de>, <linux@...ck-us.net>,
<Anand.Umarji@....com>, Akshay Gupta <akshay.gupta@....com>, "Naveen Krishna
Chatradhi" <naveenkrishna.chatradhi@....com>
Subject: [PATCH v1 2/5] misc: amd-sbi: Add support for SB-RMI over I3C
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@....com>
Signed-off-by: Akshay Gupta <akshay.gupta@....com>
---
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>
+#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) {
+ 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;
+ 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);
+
+ 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");
+}
+
+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);
+
+MODULE_IMPORT_NS("AMD_SBRMI");
+MODULE_AUTHOR("Akshay Gupta <akshay.gupta@....com>");
+MODULE_AUTHOR("Naveen Krishna Chatradhi <naveenkrishna.chatradhi@....com>");
+MODULE_DESCRIPTION("AMD SB-RMI driver over I3C");
+MODULE_LICENSE("GPL");
--
2.25.1
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