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
sbrmi_enable_alert(struct sbrmi_data * data)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
sbrmi_get_max_pwr_limit(struct sbrmi_data * data)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
sbrmi_i2c_probe(struct i2c_client * client)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
sbrmi_i2c_remove(struct i2c_client * client)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