windfarm_max6690_sensor.c

  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
 27struct 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
 34static 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
 50static 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
 57static 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
 63static 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
106static 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
114static const struct i2c_device_id wf_max6690_id[] = {
115	{ "MAC,max6690" },
116	{ }
117};
118MODULE_DEVICE_TABLE(i2c, wf_max6690_id);
119
120static const struct of_device_id wf_max6690_of_id[] = {
121	{ .compatible = "max6690", },
122	{ }
123};
124MODULE_DEVICE_TABLE(of, wf_max6690_of_id);
125
126static struct i2c_driver wf_max6690_driver = {
127	.driver = {
128		.name		= "wf_max6690",
129		.of_match_table = wf_max6690_of_id,
130	},
131	.probe		= wf_max6690_probe,
132	.remove		= wf_max6690_remove,
133	.id_table	= wf_max6690_id,
134};
135
136module_i2c_driver(wf_max6690_driver);
137
138MODULE_AUTHOR("Paul Mackerras <paulus@samba.org>");
139MODULE_DESCRIPTION("MAX6690 sensor objects for PowerMac thermal control");
140MODULE_LICENSE("GPL");