windfarm_lm87_sensor.c

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/*
 * Windfarm PowerMac thermal control. LM87 sensor
 *
 * Copyright 2012 Benjamin Herrenschmidt, IBM Corp.
 *
 * Released under the term of the GNU GPL v2.
 *
 */

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/i2c.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/io.h>
#include <asm/sections.h>
#include <asm/pmac_low_i2c.h>

#include "windfarm.h"

#define VERSION "1.0"

#undef DEBUG

#ifdef DEBUG
#define DBG(args...)    printk(args)
#else
#define DBG(args...)    do { } while(0)
#endif

struct wf_lm87_sensor {
    struct i2c_client   *i2c;
    struct wf_sensor    sens;
};
#define wf_to_lm87(c) container_of(c, struct wf_lm87_sensor, sens)


static int wf_lm87_read_reg(struct i2c_client *chip, int reg)
{
    int rc, tries = 0;
    u8 buf;

    for (;;) {
        /* Set address */
        buf = (u8)reg;
        rc = i2c_master_send(chip, &buf, 1);
        if (rc <= 0)
            goto error;
        rc = i2c_master_recv(chip, &buf, 1);
        if (rc <= 0)
            goto error;
        return (int)buf;
    error:
        DBG("wf_lm87: Error reading LM87, retrying...\n");
        if (++tries > 10) {
            printk(KERN_ERR "wf_lm87: Error reading LM87 !\n");
            return -EIO;
        }
        msleep(10);
    }
}

static int wf_lm87_get(struct wf_sensor *sr, s32 *value)
{
    struct wf_lm87_sensor *lm = sr->priv;
    s32 temp;

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

#define LM87_INT_TEMP       0x27

    /* Read temperature register */
    temp = wf_lm87_read_reg(lm->i2c, LM87_INT_TEMP);
    if (temp < 0)
        return temp;
    *value = temp << 16;

    return 0;
}

static void wf_lm87_release(struct wf_sensor *sr)
{
    struct wf_lm87_sensor *lm = wf_to_lm87(sr);

    kfree(lm);
}

static struct wf_sensor_ops wf_lm87_ops = {
    .get_value  = wf_lm87_get,
    .release    = wf_lm87_release,
    .owner      = THIS_MODULE,
};

static int wf_lm87_probe(struct i2c_client *client,
             const struct i2c_device_id *id)
{   
    struct wf_lm87_sensor *lm;
    const char *name = NULL, *loc;
    struct device_node *np = NULL;
    int rc;

    /*
     * The lm87 contains a whole pile of sensors, additionally,
     * the Xserve G5 has several lm87's. However, for now we only
     * care about the internal temperature sensor
     */
    while ((np = of_get_next_child(client->dev.of_node, np)) != NULL) {
        if (strcmp(np->name, "int-temp"))
            continue;
        loc = of_get_property(np, "location", NULL);
        if (!loc)
            continue;
        if (strstr(loc, "DIMM"))
            name = "dimms-temp";
        else if (strstr(loc, "Processors"))
            name = "between-cpus-temp";
        if (name) {
            of_node_put(np);
            break;
        }
    }
    if (!name) {
        pr_warning("wf_lm87: Unsupported sensor %s\n",
               client->dev.of_node->full_name);
        return -ENODEV;
    }

    lm = kzalloc(sizeof(struct wf_lm87_sensor), GFP_KERNEL);
    if (lm == NULL)
        return -ENODEV;

    lm->i2c = client;
    lm->sens.name = name;
    lm->sens.ops = &wf_lm87_ops;
    lm->sens.priv = lm;
    i2c_set_clientdata(client, lm);

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

static int wf_lm87_remove(struct i2c_client *client)
{
    struct wf_lm87_sensor *lm = i2c_get_clientdata(client);

    DBG("wf_lm87: i2c detatch called for %s\n", lm->sens.name);

    /* Mark client detached */
    lm->i2c = NULL;

    /* release sensor */
    wf_unregister_sensor(&lm->sens);

    return 0;
}

static const struct i2c_device_id wf_lm87_id[] = {
    { "MAC,lm87cimt", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, wf_lm87_id);

static struct i2c_driver wf_lm87_driver = {
    .driver = {
        .name   = "wf_lm87",
    },
    .probe      = wf_lm87_probe,
    .remove     = wf_lm87_remove,
    .id_table   = wf_lm87_id,
};

static int __init wf_lm87_sensor_init(void)
{
    /* We only support this on the Xserve */
    if (!of_machine_is_compatible("RackMac3,1"))
        return -ENODEV;

    return i2c_add_driver(&wf_lm87_driver);
}

static void __exit wf_lm87_sensor_exit(void)
{
    i2c_del_driver(&wf_lm87_driver);
}


module_init(wf_lm87_sensor_init);
module_exit(wf_lm87_sensor_exit);

MODULE_AUTHOR("Benjamin Herrenschmidt <[email protected]>");
MODULE_DESCRIPTION("LM87 sensor objects for PowerMacs thermal control");
MODULE_LICENSE("GPL");