1 /*
2  * Windfarm PowerMac thermal control. LM87 sensor
3  *
4  * Copyright 2012 Benjamin Herrenschmidt, IBM Corp.
5  *
6  * Released under the term of the GNU GPL v2.
7  *
8  */
9 
10 #include <linux/types.h>
11 #include <linux/errno.h>
12 #include <linux/kernel.h>
13 #include <linux/delay.h>
14 #include <linux/slab.h>
15 #include <linux/init.h>
16 #include <linux/wait.h>
17 #include <linux/i2c.h>
18 #include <asm/prom.h>
19 #include <asm/machdep.h>
20 #include <asm/io.h>
21 #include <asm/sections.h>
22 #include <asm/pmac_low_i2c.h>
23 
24 #include "windfarm.h"
25 
26 #define VERSION "1.0"
27 
28 #undef DEBUG
29 
30 #ifdef DEBUG
31 #define DBG(args...)	printk(args)
32 #else
33 #define DBG(args...)	do { } while(0)
34 #endif
35 
36 struct wf_lm87_sensor {
37 	struct i2c_client	*i2c;
38 	struct wf_sensor	sens;
39 };
40 #define wf_to_lm87(c) container_of(c, struct wf_lm87_sensor, sens)
41 
42 
43 static int wf_lm87_read_reg(struct i2c_client *chip, int reg)
44 {
45 	int rc, tries = 0;
46 	u8 buf;
47 
48 	for (;;) {
49 		/* Set address */
50 		buf = (u8)reg;
51 		rc = i2c_master_send(chip, &buf, 1);
52 		if (rc <= 0)
53 			goto error;
54 		rc = i2c_master_recv(chip, &buf, 1);
55 		if (rc <= 0)
56 			goto error;
57 		return (int)buf;
58 	error:
59 		DBG("wf_lm87: Error reading LM87, retrying...\n");
60 		if (++tries > 10) {
61 			printk(KERN_ERR "wf_lm87: Error reading LM87 !\n");
62 			return -EIO;
63 		}
64 		msleep(10);
65 	}
66 }
67 
68 static int wf_lm87_get(struct wf_sensor *sr, s32 *value)
69 {
70 	struct wf_lm87_sensor *lm = sr->priv;
71 	s32 temp;
72 
73 	if (lm->i2c == NULL)
74 		return -ENODEV;
75 
76 #define LM87_INT_TEMP		0x27
77 
78 	/* Read temperature register */
79 	temp = wf_lm87_read_reg(lm->i2c, LM87_INT_TEMP);
80 	if (temp < 0)
81 		return temp;
82 	*value = temp << 16;
83 
84 	return 0;
85 }
86 
87 static void wf_lm87_release(struct wf_sensor *sr)
88 {
89 	struct wf_lm87_sensor *lm = wf_to_lm87(sr);
90 
91 	kfree(lm);
92 }
93 
94 static const struct wf_sensor_ops wf_lm87_ops = {
95 	.get_value	= wf_lm87_get,
96 	.release	= wf_lm87_release,
97 	.owner		= THIS_MODULE,
98 };
99 
100 static int wf_lm87_probe(struct i2c_client *client,
101 			 const struct i2c_device_id *id)
102 {
103 	struct wf_lm87_sensor *lm;
104 	const char *name = NULL, *loc;
105 	struct device_node *np = NULL;
106 	int rc;
107 
108 	/*
109 	 * The lm87 contains a whole pile of sensors, additionally,
110 	 * the Xserve G5 has several lm87's. However, for now we only
111 	 * care about the internal temperature sensor
112 	 */
113 	for_each_child_of_node(client->dev.of_node, np) {
114 		if (!of_node_name_eq(np, "int-temp"))
115 			continue;
116 		loc = of_get_property(np, "location", NULL);
117 		if (!loc)
118 			continue;
119 		if (strstr(loc, "DIMM"))
120 			name = "dimms-temp";
121 		else if (strstr(loc, "Processors"))
122 			name = "between-cpus-temp";
123 		if (name) {
124 			of_node_put(np);
125 			break;
126 		}
127 	}
128 	if (!name) {
129 		pr_warning("wf_lm87: Unsupported sensor %pOF\n",
130 			   client->dev.of_node);
131 		return -ENODEV;
132 	}
133 
134 	lm = kzalloc(sizeof(struct wf_lm87_sensor), GFP_KERNEL);
135 	if (lm == NULL)
136 		return -ENODEV;
137 
138 	lm->i2c = client;
139 	lm->sens.name = name;
140 	lm->sens.ops = &wf_lm87_ops;
141 	lm->sens.priv = lm;
142 	i2c_set_clientdata(client, lm);
143 
144 	rc = wf_register_sensor(&lm->sens);
145 	if (rc)
146 		kfree(lm);
147 	return rc;
148 }
149 
150 static int wf_lm87_remove(struct i2c_client *client)
151 {
152 	struct wf_lm87_sensor *lm = i2c_get_clientdata(client);
153 
154 	DBG("wf_lm87: i2c detatch called for %s\n", lm->sens.name);
155 
156 	/* Mark client detached */
157 	lm->i2c = NULL;
158 
159 	/* release sensor */
160 	wf_unregister_sensor(&lm->sens);
161 
162 	return 0;
163 }
164 
165 static const struct i2c_device_id wf_lm87_id[] = {
166 	{ "MAC,lm87cimt", 0 },
167 	{ }
168 };
169 MODULE_DEVICE_TABLE(i2c, wf_lm87_id);
170 
171 static struct i2c_driver wf_lm87_driver = {
172 	.driver = {
173 		.name	= "wf_lm87",
174 	},
175 	.probe		= wf_lm87_probe,
176 	.remove		= wf_lm87_remove,
177 	.id_table	= wf_lm87_id,
178 };
179 
180 static int __init wf_lm87_sensor_init(void)
181 {
182 	/* We only support this on the Xserve */
183 	if (!of_machine_is_compatible("RackMac3,1"))
184 		return -ENODEV;
185 
186 	return i2c_add_driver(&wf_lm87_driver);
187 }
188 
189 static void __exit wf_lm87_sensor_exit(void)
190 {
191 	i2c_del_driver(&wf_lm87_driver);
192 }
193 
194 
195 module_init(wf_lm87_sensor_init);
196 module_exit(wf_lm87_sensor_exit);
197 
198 MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
199 MODULE_DESCRIPTION("LM87 sensor objects for PowerMacs thermal control");
200 MODULE_LICENSE("GPL");
201 
202