1 files changed, 120 insertions, 0 deletions
diff --git a/drivers/misc/amd-sbi/rmi-hwmon.c b/drivers/misc/amd-sbi/rmi-hwmon.c
new file mode 100644
index 000000000000..f4f015605daa
--- /dev/null
+++ b/drivers/misc/amd-sbi/rmi-hwmon.c
@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * rmi-hwmon.c - hwmon sensor support for side band RMI
+ *
+ * Copyright (C) 2025 Advanced Micro Devices, Inc.
+ */
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <uapi/misc/amd-apml.h>
+#include "rmi-core.h"
+
+/* Do not allow setting negative power limit */
+#define SBRMI_PWR_MIN  0
+
+static int sbrmi_read(struct device *dev, enum hwmon_sensor_types type,
+		      u32 attr, int channel, long *val)
+{
+	struct sbrmi_data *data = dev_get_drvdata(dev);
+	struct apml_mbox_msg msg = { 0 };
+	int ret;
+
+	if (!data)
+		return -ENODEV;
+
+	if (type != hwmon_power)
+		return -EINVAL;
+
+	switch (attr) {
+	case hwmon_power_input:
+		msg.cmd = SBRMI_READ_PKG_PWR_CONSUMPTION;
+		ret = rmi_mailbox_xfer(data, &msg);
+		break;
+	case hwmon_power_cap:
+		msg.cmd = SBRMI_READ_PKG_PWR_LIMIT;
+		ret = rmi_mailbox_xfer(data, &msg);
+		break;
+	case hwmon_power_cap_max:
+		msg.mb_in_out = data->pwr_limit_max;
+		ret = 0;
+		break;
+	default:
+		return -EINVAL;
+	}
+	if (ret < 0)
+		return ret;
+	/* hwmon power attributes are in microWatt */
+	*val = (long)msg.mb_in_out * 1000;
+	return ret;
+}
+
+static int sbrmi_write(struct device *dev, enum hwmon_sensor_types type,
+		       u32 attr, int channel, long val)
+{
+	struct sbrmi_data *data = dev_get_drvdata(dev);
+	struct apml_mbox_msg msg = { 0 };
+
+	if (!data)
+		return -ENODEV;
+
+	if (type != hwmon_power && attr != hwmon_power_cap)
+		return -EINVAL;
+	/*
+	 * hwmon power attributes are in microWatt
+	 * mailbox read/write is in mWatt
+	 */
+	val /= 1000;
+
+	val = clamp_val(val, SBRMI_PWR_MIN, data->pwr_limit_max);
+
+	msg.cmd = SBRMI_WRITE_PKG_PWR_LIMIT;
+	msg.mb_in_out = val;
+
+	return rmi_mailbox_xfer(data, &msg);
+}
+
+static umode_t sbrmi_is_visible(const void *data,
+				enum hwmon_sensor_types type,
+				u32 attr, int channel)
+{
+	switch (type) {
+	case hwmon_power:
+		switch (attr) {
+		case hwmon_power_input:
+		case hwmon_power_cap_max:
+			return 0444;
+		case hwmon_power_cap:
+			return 0644;
+		}
+		break;
+	default:
+		break;
+	}
+	return 0;
+}
+
+static const struct hwmon_channel_info * const sbrmi_info[] = {
+	HWMON_CHANNEL_INFO(power,
+			   HWMON_P_INPUT | HWMON_P_CAP | HWMON_P_CAP_MAX),
+	NULL
+};
+
+static const struct hwmon_ops sbrmi_hwmon_ops = {
+	.is_visible = sbrmi_is_visible,
+	.read = sbrmi_read,
+	.write = sbrmi_write,
+};
+
+static const struct hwmon_chip_info sbrmi_chip_info = {
+	.ops = &sbrmi_hwmon_ops,
+	.info = sbrmi_info,
+};
+
+int create_hwmon_sensor_device(struct device *dev, struct sbrmi_data *data)
+{
+	struct device *hwmon_dev;
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, "sbrmi", data,
+							 &sbrmi_chip_info, NULL);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}