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 #include <asm/prom.h>
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 			    const struct i2c_device_id *id)
65 {
66 	const char *name, *loc;
67 	struct wf_6690_sensor *max;
68 	int rc;
69 
70 	loc = of_get_property(client->dev.of_node, "hwsensor-location", NULL);
71 	if (!loc) {
72 		dev_warn(&client->dev, "Missing hwsensor-location property!\n");
73 		return -ENXIO;
74 	}
75 
76 	/*
77 	 * We only expose the external temperature register for
78 	 * now as this is all we need for our control loops
79 	 */
80 	if (!strcmp(loc, "BACKSIDE") || !strcmp(loc, "SYS CTRLR AMBIENT"))
81 		name = "backside-temp";
82 	else if (!strcmp(loc, "NB Ambient"))
83 		name = "north-bridge-temp";
84 	else if (!strcmp(loc, "GPU Ambient"))
85 		name = "gpu-temp";
86 	else
87 		return -ENXIO;
88 
89 	max = kzalloc(sizeof(struct wf_6690_sensor), GFP_KERNEL);
90 	if (max == NULL) {
91 		printk(KERN_ERR "windfarm: Couldn't create MAX6690 sensor: "
92 		       "no memory\n");
93 		return -ENOMEM;
94 	}
95 
96 	max->i2c = client;
97 	max->sens.name = name;
98 	max->sens.ops = &wf_max6690_ops;
99 	i2c_set_clientdata(client, max);
100 
101 	rc = wf_register_sensor(&max->sens);
102 	if (rc)
103 		kfree(max);
104 	return rc;
105 }
106 
107 static int wf_max6690_remove(struct i2c_client *client)
108 {
109 	struct wf_6690_sensor *max = i2c_get_clientdata(client);
110 
111 	max->i2c = NULL;
112 	wf_unregister_sensor(&max->sens);
113 
114 	return 0;
115 }
116 
117 static const struct i2c_device_id wf_max6690_id[] = {
118 	{ "MAC,max6690", 0 },
119 	{ }
120 };
121 MODULE_DEVICE_TABLE(i2c, wf_max6690_id);
122 
123 static struct i2c_driver wf_max6690_driver = {
124 	.driver = {
125 		.name		= "wf_max6690",
126 	},
127 	.probe		= wf_max6690_probe,
128 	.remove		= wf_max6690_remove,
129 	.id_table	= wf_max6690_id,
130 };
131 
132 module_i2c_driver(wf_max6690_driver);
133 
134 MODULE_AUTHOR("Paul Mackerras <paulus@samba.org>");
135 MODULE_DESCRIPTION("MAX6690 sensor objects for PowerMac thermal control");
136 MODULE_LICENSE("GPL");
137