1 files changed, 133 insertions, 0 deletions
diff --git a/drivers/misc/amd-sbi/rmi-i2c.c b/drivers/misc/amd-sbi/rmi-i2c.c
new file mode 100644
index 000000000000..f891f5af4bc6
--- /dev/null
+++ b/drivers/misc/amd-sbi/rmi-i2c.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * rmi-i2c.c - Side band RMI over I2C support for AMD out
+ *             of band management
+ *
+ * Copyright (C) 2024 Advanced Micro Devices, Inc.
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/i2c.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_i2c_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct sbrmi_data *data;
+	struct regmap_config sbrmi_i2c_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_i2c(client, &sbrmi_i2c_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;
+
+	data->dev_static_addr = client->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_i2c_remove(struct i2c_client *client)
+{
+	struct sbrmi_data *data = dev_get_drvdata(&client->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(&client->dev, "Removed sbrmi-i2c driver\n");
+	return;
+}
+
+static const struct i2c_device_id sbrmi_id[] = {
+	{"sbrmi-i2c"},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, sbrmi_id);
+
+static const struct of_device_id __maybe_unused sbrmi_of_match[] = {
+	{
+		.compatible = "amd,sbrmi",
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, sbrmi_of_match);
+
+static struct i2c_driver sbrmi_driver = {
+	.driver = {
+		.name = "sbrmi-i2c",
+		.of_match_table = of_match_ptr(sbrmi_of_match),
+	},
+	.probe = sbrmi_i2c_probe,
+	.remove = sbrmi_i2c_remove,
+	.id_table = sbrmi_id,
+};
+
+module_i2c_driver(sbrmi_driver);
+
+MODULE_AUTHOR("Akshay Gupta <akshay.gupta@amd.com>");
+MODULE_AUTHOR("Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>");
+MODULE_DESCRIPTION("Hwmon driver for AMD SB-RMI emulated sensor");
+MODULE_LICENSE("GPL");