1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * rmi-i2c.c - Side band RMI over I2C support for AMD out
4  *             of band management
5  *
6  * Copyright (C) 2024 Advanced Micro Devices, Inc.
7  */
8 
9 #include <linux/delay.h>
10 #include <linux/err.h>
11 #include <linux/i2c.h>
12 #include <linux/init.h>
13 #include <linux/module.h>
14 #include <linux/mutex.h>
15 #include <linux/of.h>
16 #include <linux/regmap.h>
17 #include "rmi-core.h"
18 
19 static int sbrmi_enable_alert(struct sbrmi_data *data)
20 {
21 	int ctrl, ret;
22 
23 	/*
24 	 * Enable the SB-RMI Software alert status
25 	 * by writing 0 to bit 4 of Control register(0x1)
26 	 */
27 	ret = regmap_read(data->regmap, SBRMI_CTRL, &ctrl);
28 	if (ret < 0)
29 		return ret;
30 
31 	if (ctrl & 0x10) {
32 		ctrl &= ~0x10;
33 		return regmap_write(data->regmap, SBRMI_CTRL, ctrl);
34 	}
35 
36 	return 0;
37 }
38 
39 static int sbrmi_get_max_pwr_limit(struct sbrmi_data *data)
40 {
41 	struct apml_mbox_msg msg = { 0 };
42 	int ret;
43 
44 	msg.cmd = SBRMI_READ_PKG_MAX_PWR_LIMIT;
45 	ret = rmi_mailbox_xfer(data, &msg);
46 	if (ret < 0)
47 		return ret;
48 	data->pwr_limit_max = msg.mb_in_out;
49 
50 	return ret;
51 }
52 
53 static int sbrmi_i2c_probe(struct i2c_client *client)
54 {
55 	struct device *dev = &client->dev;
56 	struct sbrmi_data *data;
57 	struct regmap_config sbrmi_i2c_regmap_config = {
58 		.reg_bits = 8,
59 		.val_bits = 8,
60 	};
61 	int ret;
62 
63 	data = devm_kzalloc(dev, sizeof(struct sbrmi_data), GFP_KERNEL);
64 	if (!data)
65 		return -ENOMEM;
66 
67 	mutex_init(&data->lock);
68 
69 	data->regmap = devm_regmap_init_i2c(client, &sbrmi_i2c_regmap_config);
70 	if (IS_ERR(data->regmap))
71 		return PTR_ERR(data->regmap);
72 
73 	/* Enable alert for SB-RMI sequence */
74 	ret = sbrmi_enable_alert(data);
75 	if (ret < 0)
76 		return ret;
77 
78 	/* Cache maximum power limit */
79 	ret = sbrmi_get_max_pwr_limit(data);
80 	if (ret < 0)
81 		return ret;
82 
83 	data->dev_static_addr = client->addr;
84 	dev_set_drvdata(dev, data);
85 
86 	ret = create_hwmon_sensor_device(dev, data);
87 	if (ret < 0)
88 		return ret;
89 	return create_misc_rmi_device(data, dev);
90 }
91 
92 static void sbrmi_i2c_remove(struct i2c_client *client)
93 {
94 	struct sbrmi_data *data = dev_get_drvdata(&client->dev);
95 
96 	misc_deregister(&data->sbrmi_misc_dev);
97 	/* Assign fops and parent of misc dev to NULL */
98 	data->sbrmi_misc_dev.fops = NULL;
99 	data->sbrmi_misc_dev.parent = NULL;
100 	dev_info(&client->dev, "Removed sbrmi-i2c driver\n");
101 	return;
102 }
103 
104 static const struct i2c_device_id sbrmi_id[] = {
105 	{"sbrmi-i2c"},
106 	{}
107 };
108 MODULE_DEVICE_TABLE(i2c, sbrmi_id);
109 
110 static const struct of_device_id __maybe_unused sbrmi_of_match[] = {
111 	{
112 		.compatible = "amd,sbrmi",
113 	},
114 	{ },
115 };
116 MODULE_DEVICE_TABLE(of, sbrmi_of_match);
117 
118 static struct i2c_driver sbrmi_driver = {
119 	.driver = {
120 		.name = "sbrmi-i2c",
121 		.of_match_table = of_match_ptr(sbrmi_of_match),
122 	},
123 	.probe = sbrmi_i2c_probe,
124 	.remove = sbrmi_i2c_remove,
125 	.id_table = sbrmi_id,
126 };
127 
128 module_i2c_driver(sbrmi_driver);
129 
130 MODULE_AUTHOR("Akshay Gupta <akshay.gupta@amd.com>");
131 MODULE_AUTHOR("Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>");
132 MODULE_DESCRIPTION("Hwmon driver for AMD SB-RMI emulated sensor");
133 MODULE_LICENSE("GPL");
134