windfarm_max6690_sensor.c

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/*
 * Windfarm PowerMac thermal control.  MAX6690 sensor.
 *
 * Copyright (C) 2005 Paul Mackerras, IBM Corp. <[email protected]>
 *
 * Use and redistribute under the terms of the GNU GPL v2.
 */
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <asm/prom.h>
#include <asm/pmac_low_i2c.h>

#include "windfarm.h"

#define VERSION "1.0"

/* This currently only exports the external temperature sensor,
   since that's all the control loops need. */

/* Some MAX6690 register numbers */
#define MAX6690_INTERNAL_TEMP   0
#define MAX6690_EXTERNAL_TEMP   1

struct wf_6690_sensor {
    struct i2c_client   *i2c;
    struct wf_sensor    sens;
};

#define wf_to_6690(x)   container_of((x), struct wf_6690_sensor, sens)

static int wf_max6690_get(struct wf_sensor *sr, s32 *value)
{
    struct wf_6690_sensor *max = wf_to_6690(sr);
    s32 data;

    if (max->i2c == NULL)
        return -ENODEV;

    /* chip gets initialized by firmware */
    data = i2c_smbus_read_byte_data(max->i2c, MAX6690_EXTERNAL_TEMP);
    if (data < 0)
        return data;
    *value = data << 16;
    return 0;
}

static void wf_max6690_release(struct wf_sensor *sr)
{
    struct wf_6690_sensor *max = wf_to_6690(sr);

    kfree(max);
}

static struct wf_sensor_ops wf_max6690_ops = {
    .get_value  = wf_max6690_get,
    .release    = wf_max6690_release,
    .owner      = THIS_MODULE,
};

static int wf_max6690_probe(struct i2c_client *client,
                const struct i2c_device_id *id)
{
    const char *name, *loc;
    struct wf_6690_sensor *max;
    int rc;

    loc = of_get_property(client->dev.of_node, "hwsensor-location", NULL);
    if (!loc) {
        dev_warn(&client->dev, "Missing hwsensor-location property!\n");
        return -ENXIO;
    }

    /*
     * We only expose the external temperature register for
     * now as this is all we need for our control loops
     */
    if (!strcmp(loc, "BACKSIDE") || !strcmp(loc, "SYS CTRLR AMBIENT"))
        name = "backside-temp";
    else if (!strcmp(loc, "NB Ambient"))
        name = "north-bridge-temp";
    else if (!strcmp(loc, "GPU Ambient"))
        name = "gpu-temp";
    else
        return -ENXIO;

    max = kzalloc(sizeof(struct wf_6690_sensor), GFP_KERNEL);
    if (max == NULL) {
        printk(KERN_ERR "windfarm: Couldn't create MAX6690 sensor: "
               "no memory\n");
        return -ENOMEM;
    }

    max->i2c = client;
    max->sens.name = (char *)name; /* XXX fix constness in structure */
    max->sens.ops = &wf_max6690_ops;
    i2c_set_clientdata(client, max);

    rc = wf_register_sensor(&max->sens);
    if (rc)
        kfree(max);
    return rc;
}

static int wf_max6690_remove(struct i2c_client *client)
{
    struct wf_6690_sensor *max = i2c_get_clientdata(client);

    max->i2c = NULL;
    wf_unregister_sensor(&max->sens);

    return 0;
}

static const struct i2c_device_id wf_max6690_id[] = {
    { "MAC,max6690", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, wf_max6690_id);

static struct i2c_driver wf_max6690_driver = {
    .driver = {
        .name       = "wf_max6690",
    },
    .probe      = wf_max6690_probe,
    .remove     = wf_max6690_remove,
    .id_table   = wf_max6690_id,
};

static int __init wf_max6690_sensor_init(void)
{
    return i2c_add_driver(&wf_max6690_driver);
}

static void __exit wf_max6690_sensor_exit(void)
{
    i2c_del_driver(&wf_max6690_driver);
}

module_init(wf_max6690_sensor_init);
module_exit(wf_max6690_sensor_exit);

MODULE_AUTHOR("Paul Mackerras <[email protected]>");
MODULE_DESCRIPTION("MAX6690 sensor objects for PowerMac thermal control");
MODULE_LICENSE("GPL");