1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Windfarm PowerMac thermal control.  MAX6690 sensor.
4  *
5  * Copyright (C) 2005 Paul Mackerras, IBM Corp. <paulus@samba.org>
6  */
7 #include <linux/types.h>
8 #include <linux/errno.h>
9 #include <linux/kernel.h>
10 #include <linux/init.h>
11 #include <linux/slab.h>
12 #include <linux/i2c.h>
13 
14 #include <asm/pmac_low_i2c.h>
15 
16 #include "windfarm.h"
17 
18 #define VERSION "1.0"
19 
20 /* This currently only exports the external temperature sensor,
21    since that's all the control loops need. */
22 
23 /* Some MAX6690 register numbers */
24 #define MAX6690_INTERNAL_TEMP	0
25 #define MAX6690_EXTERNAL_TEMP	1
26 
27 struct wf_6690_sensor {
28 	struct i2c_client	*i2c;
29 	struct wf_sensor	sens;
30 };
31 
32 #define wf_to_6690(x)	container_of((x), struct wf_6690_sensor, sens)
33 
34 static int wf_max6690_get(struct wf_sensor *sr, s32 *value)
35 {
36 	struct wf_6690_sensor *max = wf_to_6690(sr);
37 	s32 data;
38 
39 	if (max->i2c == NULL)
40 		return -ENODEV;
41 
42 	/* chip gets initialized by firmware */
43 	data = i2c_smbus_read_byte_data(max->i2c, MAX6690_EXTERNAL_TEMP);
44 	if (data < 0)
45 		return data;
46 	*value = data << 16;
47 	return 0;
48 }
49 
50 static void wf_max6690_release(struct wf_sensor *sr)
51 {
52 	struct wf_6690_sensor *max = wf_to_6690(sr);
53 
54 	kfree(max);
55 }
56 
57 static const struct wf_sensor_ops wf_max6690_ops = {
58 	.get_value	= wf_max6690_get,
59 	.release	= wf_max6690_release,
60 	.owner		= THIS_MODULE,
61 };
62 
63 static int wf_max6690_probe(struct i2c_client *client)
64 {
65 	const char *name, *loc;
66 	struct wf_6690_sensor *max;
67 	int rc;
68 
69 	loc = of_get_property(client->dev.of_node, "hwsensor-location", NULL);
70 	if (!loc) {
71 		dev_warn(&client->dev, "Missing hwsensor-location property!\n");
72 		return -ENXIO;
73 	}
74 
75 	/*
76 	 * We only expose the external temperature register for
77 	 * now as this is all we need for our control loops
78 	 */
79 	if (!strcmp(loc, "BACKSIDE") || !strcmp(loc, "SYS CTRLR AMBIENT"))
80 		name = "backside-temp";
81 	else if (!strcmp(loc, "NB Ambient"))
82 		name = "north-bridge-temp";
83 	else if (!strcmp(loc, "GPU Ambient"))
84 		name = "gpu-temp";
85 	else
86 		return -ENXIO;
87 
88 	max = kzalloc(sizeof(struct wf_6690_sensor), GFP_KERNEL);
89 	if (max == NULL) {
90 		printk(KERN_ERR "windfarm: Couldn't create MAX6690 sensor: "
91 		       "no memory\n");
92 		return -ENOMEM;
93 	}
94 
95 	max->i2c = client;
96 	max->sens.name = name;
97 	max->sens.ops = &wf_max6690_ops;
98 	i2c_set_clientdata(client, max);
99 
100 	rc = wf_register_sensor(&max->sens);
101 	if (rc)
102 		kfree(max);
103 	return rc;
104 }
105 
106 static void wf_max6690_remove(struct i2c_client *client)
107 {
108 	struct wf_6690_sensor *max = i2c_get_clientdata(client);
109 
110 	max->i2c = NULL;
111 	wf_unregister_sensor(&max->sens);
112 }
113 
114 static const struct i2c_device_id wf_max6690_id[] = {
115 	{ "MAC,max6690", 0 },
116 	{ }
117 };
118 MODULE_DEVICE_TABLE(i2c, wf_max6690_id);
119 
120 static const struct of_device_id wf_max6690_of_id[] = {
121 	{ .compatible = "max6690", },
122 	{ }
123 };
124 MODULE_DEVICE_TABLE(of, wf_max6690_of_id);
125 
126 static struct i2c_driver wf_max6690_driver = {
127 	.driver = {
128 		.name		= "wf_max6690",
129 		.of_match_table = wf_max6690_of_id,
130 	},
131 	.probe_new	= wf_max6690_probe,
132 	.remove		= wf_max6690_remove,
133 	.id_table	= wf_max6690_id,
134 };
135 
136 module_i2c_driver(wf_max6690_driver);
137 
138 MODULE_AUTHOR("Paul Mackerras <paulus@samba.org>");
139 MODULE_DESCRIPTION("MAX6690 sensor objects for PowerMac thermal control");
140 MODULE_LICENSE("GPL");
141