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 "0.2"
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
28struct 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#define i2c_to_6690(x)	container_of((x), struct wf_6690_sensor, i2c)
35
36static int wf_max6690_attach(struct i2c_adapter *adapter);
37static int wf_max6690_detach(struct i2c_client *client);
38
39static struct i2c_driver wf_max6690_driver = {
40	.driver = {
41		.name		= "wf_max6690",
42	},
43	.attach_adapter	= wf_max6690_attach,
44	.detach_client	= wf_max6690_detach,
45};
46
47static int wf_max6690_get(struct wf_sensor *sr, s32 *value)
48{
49	struct wf_6690_sensor *max = wf_to_6690(sr);
50	s32 data;
51
52	if (max->i2c.adapter == NULL)
53		return -ENODEV;
54
55	/* chip gets initialized by firmware */
56	data = i2c_smbus_read_byte_data(&max->i2c, MAX6690_EXTERNAL_TEMP);
57	if (data < 0)
58		return data;
59	*value = data << 16;
60	return 0;
61}
62
63static void wf_max6690_release(struct wf_sensor *sr)
64{
65	struct wf_6690_sensor *max = wf_to_6690(sr);
66
67	if (max->i2c.adapter) {
68		i2c_detach_client(&max->i2c);
69		max->i2c.adapter = NULL;
70	}
71	kfree(max);
72}
73
74static struct wf_sensor_ops wf_max6690_ops = {
75	.get_value	= wf_max6690_get,
76	.release	= wf_max6690_release,
77	.owner		= THIS_MODULE,
78};
79
80static void wf_max6690_create(struct i2c_adapter *adapter, u8 addr)
81{
82	struct wf_6690_sensor *max;
83	char *name = "backside-temp";
84
85	max = kzalloc(sizeof(struct wf_6690_sensor), GFP_KERNEL);
86	if (max == NULL) {
87		printk(KERN_ERR "windfarm: Couldn't create MAX6690 sensor %s: "
88		       "no memory\n", name);
89		return;
90	}
91
92	max->sens.ops = &wf_max6690_ops;
93	max->sens.name = name;
94	max->i2c.addr = addr >> 1;
95	max->i2c.adapter = adapter;
96	max->i2c.driver = &wf_max6690_driver;
97	strncpy(max->i2c.name, name, I2C_NAME_SIZE-1);
98
99	if (i2c_attach_client(&max->i2c)) {
100		printk(KERN_ERR "windfarm: failed to attach MAX6690 sensor\n");
101		goto fail;
102	}
103
104	if (wf_register_sensor(&max->sens)) {
105		i2c_detach_client(&max->i2c);
106		goto fail;
107	}
108
109	return;
110
111 fail:
112	kfree(max);
113}
114
115static int wf_max6690_attach(struct i2c_adapter *adapter)
116{
117	struct device_node *busnode, *dev = NULL;
118	struct pmac_i2c_bus *bus;
119	const char *loc;
120
121	bus = pmac_i2c_adapter_to_bus(adapter);
122	if (bus == NULL)
123		return -ENODEV;
124	busnode = pmac_i2c_get_bus_node(bus);
125
126	while ((dev = of_get_next_child(busnode, dev)) != NULL) {
127		u8 addr;
128
129		/* We must re-match the adapter in order to properly check
130		 * the channel on multibus setups
131		 */
132		if (!pmac_i2c_match_adapter(dev, adapter))
133			continue;
134		if (!of_device_is_compatible(dev, "max6690"))
135			continue;
136		addr = pmac_i2c_get_dev_addr(dev);
137		loc = of_get_property(dev, "hwsensor-location", NULL);
138		if (loc == NULL || addr == 0)
139			continue;
140		printk("found max6690, loc=%s addr=0x%02x\n", loc, addr);
141		if (strcmp(loc, "BACKSIDE"))
142			continue;
143		wf_max6690_create(adapter, addr);
144	}
145
146	return 0;
147}
148
149static int wf_max6690_detach(struct i2c_client *client)
150{
151	struct wf_6690_sensor *max = i2c_to_6690(client);
152
153	max->i2c.adapter = NULL;
154	wf_unregister_sensor(&max->sens);
155
156	return 0;
157}
158
159static int __init wf_max6690_sensor_init(void)
160{
161	/* Don't register on old machines that use therm_pm72 for now */
162	if (machine_is_compatible("PowerMac7,2") ||
163	    machine_is_compatible("PowerMac7,3") ||
164	    machine_is_compatible("RackMac3,1"))
165		return -ENODEV;
166	return i2c_add_driver(&wf_max6690_driver);
167}
168
169static void __exit wf_max6690_sensor_exit(void)
170{
171	i2c_del_driver(&wf_max6690_driver);
172}
173
174module_init(wf_max6690_sensor_init);
175module_exit(wf_max6690_sensor_exit);
176
177MODULE_AUTHOR("Paul Mackerras <paulus@samba.org>");
178MODULE_DESCRIPTION("MAX6690 sensor objects for PowerMac thermal control");
179MODULE_LICENSE("GPL");
180