1 /*
2  * Windfarm PowerMac thermal control.  MAX6690 sensor.
3  *
4  * Copyright (C) 2005 Paul Mackerras, IBM Corp. <paulus@samba.org>
5  *
6  * Use and redistribute under the terms of the GNU GPL v2.
7  */
8 #include <linux/types.h>
9 #include <linux/errno.h>
10 #include <linux/kernel.h>
11 #include <linux/init.h>
12 #include <linux/slab.h>
13 #include <linux/i2c.h>
14 #include <asm/prom.h>
15 #include <asm/pmac_low_i2c.h>
16 
17 #include "windfarm.h"
18 
19 #define VERSION "1.0"
20 
21 /* This currently only exports the external temperature sensor,
22    since that's all the control loops need. */
23 
24 /* Some MAX6690 register numbers */
25 #define MAX6690_INTERNAL_TEMP	0
26 #define MAX6690_EXTERNAL_TEMP	1
27 
28 struct wf_6690_sensor {
29 	struct i2c_client	*i2c;
30 	struct wf_sensor	sens;
31 };
32 
33 #define wf_to_6690(x)	container_of((x), struct wf_6690_sensor, sens)
34 
35 static int wf_max6690_get(struct wf_sensor *sr, s32 *value)
36 {
37 	struct wf_6690_sensor *max = wf_to_6690(sr);
38 	s32 data;
39 
40 	if (max->i2c == NULL)
41 		return -ENODEV;
42 
43 	/* chip gets initialized by firmware */
44 	data = i2c_smbus_read_byte_data(max->i2c, MAX6690_EXTERNAL_TEMP);
45 	if (data < 0)
46 		return data;
47 	*value = data << 16;
48 	return 0;
49 }
50 
51 static void wf_max6690_release(struct wf_sensor *sr)
52 {
53 	struct wf_6690_sensor *max = wf_to_6690(sr);
54 
55 	kfree(max);
56 }
57 
58 static struct wf_sensor_ops wf_max6690_ops = {
59 	.get_value	= wf_max6690_get,
60 	.release	= wf_max6690_release,
61 	.owner		= THIS_MODULE,
62 };
63 
64 static int wf_max6690_probe(struct i2c_client *client,
65 			    const struct i2c_device_id *id)
66 {
67 	const char *name, *loc;
68 	struct wf_6690_sensor *max;
69 	int rc;
70 
71 	loc = of_get_property(client->dev.of_node, "hwsensor-location", NULL);
72 	if (!loc) {
73 		dev_warn(&client->dev, "Missing hwsensor-location property!\n");
74 		return -ENXIO;
75 	}
76 
77 	/*
78 	 * We only expose the external temperature register for
79 	 * now as this is all we need for our control loops
80 	 */
81 	if (!strcmp(loc, "BACKSIDE") || !strcmp(loc, "SYS CTRLR AMBIENT"))
82 		name = "backside-temp";
83 	else if (!strcmp(loc, "NB Ambient"))
84 		name = "north-bridge-temp";
85 	else if (!strcmp(loc, "GPU Ambient"))
86 		name = "gpu-temp";
87 	else
88 		return -ENXIO;
89 
90 	max = kzalloc(sizeof(struct wf_6690_sensor), GFP_KERNEL);
91 	if (max == NULL) {
92 		printk(KERN_ERR "windfarm: Couldn't create MAX6690 sensor: "
93 		       "no memory\n");
94 		return -ENOMEM;
95 	}
96 
97 	max->i2c = client;
98 	max->sens.name = (char *)name; /* XXX fix constness in structure */
99 	max->sens.ops = &wf_max6690_ops;
100 	i2c_set_clientdata(client, max);
101 
102 	rc = wf_register_sensor(&max->sens);
103 	if (rc)
104 		kfree(max);
105 	return rc;
106 }
107 
108 static int wf_max6690_remove(struct i2c_client *client)
109 {
110 	struct wf_6690_sensor *max = i2c_get_clientdata(client);
111 
112 	max->i2c = NULL;
113 	wf_unregister_sensor(&max->sens);
114 
115 	return 0;
116 }
117 
118 static const struct i2c_device_id wf_max6690_id[] = {
119 	{ "MAC,max6690", 0 },
120 	{ }
121 };
122 MODULE_DEVICE_TABLE(i2c, wf_max6690_id);
123 
124 static struct i2c_driver wf_max6690_driver = {
125 	.driver = {
126 		.name		= "wf_max6690",
127 	},
128 	.probe		= wf_max6690_probe,
129 	.remove		= wf_max6690_remove,
130 	.id_table	= wf_max6690_id,
131 };
132 
133 static int __init wf_max6690_sensor_init(void)
134 {
135 	return i2c_add_driver(&wf_max6690_driver);
136 }
137 
138 static void __exit wf_max6690_sensor_exit(void)
139 {
140 	i2c_del_driver(&wf_max6690_driver);
141 }
142 
143 module_init(wf_max6690_sensor_init);
144 module_exit(wf_max6690_sensor_exit);
145 
146 MODULE_AUTHOR("Paul Mackerras <paulus@samba.org>");
147 MODULE_DESCRIPTION("MAX6690 sensor objects for PowerMac thermal control");
148 MODULE_LICENSE("GPL");
149