coretemp.c

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/*
 * coretemp.c - Linux kernel module for hardware monitoring
 *
 * Copyright (C) 2007 Rudolf Marek <[email protected]>
 *
 * Inspired from many hwmon drivers
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301 USA.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/hwmon.h>
#include <linux/sysfs.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/platform_device.h>
#include <linux/cpu.h>
#include <linux/pci.h>
#include <linux/smp.h>
#include <linux/moduleparam.h>
#include <asm/msr.h>
#include <asm/processor.h>
#include <asm/cpu_device_id.h>

#define DRVNAME "coretemp"

/*
 * force_tjmax only matters when TjMax can't be read from the CPU itself.
 * When set, it replaces the driver's suboptimal heuristic.
 */
static int force_tjmax;
module_param_named(tjmax, force_tjmax, int, 0444);
MODULE_PARM_DESC(tjmax, "TjMax value in degrees Celsius");

#define BASE_SYSFS_ATTR_NO  2   /* Sysfs Base attr no for coretemp */
#define NUM_REAL_CORES      32  /* Number of Real cores per cpu */
#define CORETEMP_NAME_LENGTH    17  /* String Length of attrs */
#define MAX_CORE_ATTRS      4   /* Maximum no of basic attrs */
#define TOTAL_ATTRS     (MAX_CORE_ATTRS + 1)
#define MAX_CORE_DATA       (NUM_REAL_CORES + BASE_SYSFS_ATTR_NO)

#define TO_PHYS_ID(cpu)     (cpu_data(cpu).phys_proc_id)
#define TO_CORE_ID(cpu)     (cpu_data(cpu).cpu_core_id)
#define TO_ATTR_NO(cpu)     (TO_CORE_ID(cpu) + BASE_SYSFS_ATTR_NO)

#ifdef CONFIG_SMP
#define for_each_sibling(i, cpu)    for_each_cpu(i, cpu_sibling_mask(cpu))
#else
#define for_each_sibling(i, cpu)    for (i = 0; false; )
#endif

/*
 * Per-Core Temperature Data
 * @last_updated: The time when the current temperature value was updated
 *      earlier (in jiffies).
 * @cpu_core_id: The CPU Core from which temperature values should be read
 *      This value is passed as "id" field to rdmsr/wrmsr functions.
 * @status_reg: One of IA32_THERM_STATUS or IA32_PACKAGE_THERM_STATUS,
 *      from where the temperature values should be read.
 * @attr_size:  Total number of pre-core attrs displayed in the sysfs.
 * @is_pkg_data: If this is 1, the temp_data holds pkgtemp data.
 *      Otherwise, temp_data holds coretemp data.
 * @valid: If this is 1, the current temperature is valid.
 */
struct temp_data {
    int temp;
    int ttarget;
    int tjmax;
    unsigned long last_updated;
    unsigned int cpu;
    u32 cpu_core_id;
    u32 status_reg;
    int attr_size;
    bool is_pkg_data;
    bool valid;
    struct sensor_device_attribute sd_attrs[TOTAL_ATTRS];
    char attr_name[TOTAL_ATTRS][CORETEMP_NAME_LENGTH];
    struct mutex update_lock;
};

/* Platform Data per Physical CPU */
struct platform_data {
    struct device *hwmon_dev;
    u16 phys_proc_id;
    struct temp_data *core_data[MAX_CORE_DATA];
    struct device_attribute name_attr;
};

struct pdev_entry {
    struct list_head list;
    struct platform_device *pdev;
    u16 phys_proc_id;
};

static LIST_HEAD(pdev_list);
static DEFINE_MUTEX(pdev_list_mutex);

static ssize_t show_name(struct device *dev,
            struct device_attribute *devattr, char *buf)
{
    return sprintf(buf, "%s\n", DRVNAME);
}

static ssize_t show_label(struct device *dev,
                struct device_attribute *devattr, char *buf)
{
    struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
    struct platform_data *pdata = dev_get_drvdata(dev);
    struct temp_data *tdata = pdata->core_data[attr->index];

    if (tdata->is_pkg_data)
        return sprintf(buf, "Physical id %u\n", pdata->phys_proc_id);

    return sprintf(buf, "Core %u\n", tdata->cpu_core_id);
}

static ssize_t show_crit_alarm(struct device *dev,
                struct device_attribute *devattr, char *buf)
{
    u32 eax, edx;
    struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
    struct platform_data *pdata = dev_get_drvdata(dev);
    struct temp_data *tdata = pdata->core_data[attr->index];

    rdmsr_on_cpu(tdata->cpu, tdata->status_reg, &eax, &edx);

    return sprintf(buf, "%d\n", (eax >> 5) & 1);
}

static ssize_t show_tjmax(struct device *dev,
            struct device_attribute *devattr, char *buf)
{
    struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
    struct platform_data *pdata = dev_get_drvdata(dev);

    return sprintf(buf, "%d\n", pdata->core_data[attr->index]->tjmax);
}

static ssize_t show_ttarget(struct device *dev,
                struct device_attribute *devattr, char *buf)
{
    struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
    struct platform_data *pdata = dev_get_drvdata(dev);

    return sprintf(buf, "%d\n", pdata->core_data[attr->index]->ttarget);
}

static ssize_t show_temp(struct device *dev,
            struct device_attribute *devattr, char *buf)
{
    u32 eax, edx;
    struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
    struct platform_data *pdata = dev_get_drvdata(dev);
    struct temp_data *tdata = pdata->core_data[attr->index];

    mutex_lock(&tdata->update_lock);

    /* Check whether the time interval has elapsed */
    if (!tdata->valid || time_after(jiffies, tdata->last_updated + HZ)) {
        rdmsr_on_cpu(tdata->cpu, tdata->status_reg, &eax, &edx);
        tdata->valid = 0;
        /* Check whether the data is valid */
        if (eax & 0x80000000) {
            tdata->temp = tdata->tjmax -
                    ((eax >> 16) & 0x7f) * 1000;
            tdata->valid = 1;
        }
        tdata->last_updated = jiffies;
    }

    mutex_unlock(&tdata->update_lock);
    return tdata->valid ? sprintf(buf, "%d\n", tdata->temp) : -EAGAIN;
}

struct tjmax {
    char const *id;
    int tjmax;
};

static const struct tjmax __cpuinitconst tjmax_table[] = {
    { "CPU D410", 100000 },
    { "CPU D425", 100000 },
    { "CPU D510", 100000 },
    { "CPU D525", 100000 },
    { "CPU N450", 100000 },
    { "CPU N455", 100000 },
    { "CPU N470", 100000 },
    { "CPU N475", 100000 },
    { "CPU  230", 100000 },     /* Model 0x1c, stepping 2   */
    { "CPU  330", 125000 },     /* Model 0x1c, stepping 2   */
    { "CPU CE4110", 110000 },   /* Model 0x1c, stepping 10  */
    { "CPU CE4150", 110000 },   /* Model 0x1c, stepping 10  */
    { "CPU CE4170", 110000 },   /* Model 0x1c, stepping 10  */
};

static int __cpuinit adjust_tjmax(struct cpuinfo_x86 *c, u32 id,
                  struct device *dev)
{
    /* The 100C is default for both mobile and non mobile CPUs */

    int tjmax = 100000;
    int tjmax_ee = 85000;
    int usemsr_ee = 1;
    int err;
    u32 eax, edx;
    struct pci_dev *host_bridge;
    int i;

    /* explicit tjmax table entries override heuristics */
    for (i = 0; i < ARRAY_SIZE(tjmax_table); i++) {
        if (strstr(c->x86_model_id, tjmax_table[i].id))
            return tjmax_table[i].tjmax;
    }

    /* Early chips have no MSR for TjMax */

    if (c->x86_model == 0xf && c->x86_mask < 4)
        usemsr_ee = 0;

    /* Atom CPUs */

    if (c->x86_model == 0x1c || c->x86_model == 0x26
        || c->x86_model == 0x27) {
        usemsr_ee = 0;

        host_bridge = pci_get_bus_and_slot(0, PCI_DEVFN(0, 0));

        if (host_bridge && host_bridge->vendor == PCI_VENDOR_ID_INTEL
            && (host_bridge->device == 0xa000   /* NM10 based nettop */
            || host_bridge->device == 0xa010))  /* NM10 based netbook */
            tjmax = 100000;
        else
            tjmax = 90000;

        pci_dev_put(host_bridge);
    } else if (c->x86_model == 0x36) {
        usemsr_ee = 0;
        tjmax = 100000;
    }

    if (c->x86_model > 0xe && usemsr_ee) {
        u8 platform_id;

        /*
         * Now we can detect the mobile CPU using Intel provided table
         * http://softwarecommunity.intel.com/Wiki/Mobility/720.htm
         * For Core2 cores, check MSR 0x17, bit 28 1 = Mobile CPU
         */
        err = rdmsr_safe_on_cpu(id, 0x17, &eax, &edx);
        if (err) {
            dev_warn(dev,
                 "Unable to access MSR 0x17, assuming desktop"
                 " CPU\n");
            usemsr_ee = 0;
        } else if (c->x86_model < 0x17 && !(eax & 0x10000000)) {
            /*
             * Trust bit 28 up to Penryn, I could not find any
             * documentation on that; if you happen to know
             * someone at Intel please ask
             */
            usemsr_ee = 0;
        } else {
            /* Platform ID bits 52:50 (EDX starts at bit 32) */
            platform_id = (edx >> 18) & 0x7;

            /*
             * Mobile Penryn CPU seems to be platform ID 7 or 5
             * (guesswork)
             */
            if (c->x86_model == 0x17 &&
                (platform_id == 5 || platform_id == 7)) {
                /*
                 * If MSR EE bit is set, set it to 90 degrees C,
                 * otherwise 105 degrees C
                 */
                tjmax_ee = 90000;
                tjmax = 105000;
            }
        }
    }

    if (usemsr_ee) {
        err = rdmsr_safe_on_cpu(id, 0xee, &eax, &edx);
        if (err) {
            dev_warn(dev,
                 "Unable to access MSR 0xEE, for Tjmax, left"
                 " at default\n");
        } else if (eax & 0x40000000) {
            tjmax = tjmax_ee;
        }
    } else if (tjmax == 100000) {
        /*
         * If we don't use msr EE it means we are desktop CPU
         * (with exeception of Atom)
         */
        dev_warn(dev, "Using relative temperature scale!\n");
    }

    return tjmax;
}

static int __cpuinit get_tjmax(struct cpuinfo_x86 *c, u32 id,
                   struct device *dev)
{
    int err;
    u32 eax, edx;
    u32 val;

    /*
     * A new feature of current Intel(R) processors, the
     * IA32_TEMPERATURE_TARGET contains the TjMax value
     */
    err = rdmsr_safe_on_cpu(id, MSR_IA32_TEMPERATURE_TARGET, &eax, &edx);
    if (err) {
        if (c->x86_model > 0xe && c->x86_model != 0x1c)
            dev_warn(dev, "Unable to read TjMax from CPU %u\n", id);
    } else {
        val = (eax >> 16) & 0xff;
        /*
         * If the TjMax is not plausible, an assumption
         * will be used
         */
        if (val) {
            dev_dbg(dev, "TjMax is %d degrees C\n", val);
            return val * 1000;
        }
    }

    if (force_tjmax) {
        dev_notice(dev, "TjMax forced to %d degrees C by user\n",
               force_tjmax);
        return force_tjmax * 1000;
    }

    /*
     * An assumption is made for early CPUs and unreadable MSR.
     * NOTE: the calculated value may not be correct.
     */
    return adjust_tjmax(c, id, dev);
}

static int __devinit create_name_attr(struct platform_data *pdata,
                      struct device *dev)
{
    sysfs_attr_init(&pdata->name_attr.attr);
    pdata->name_attr.attr.name = "name";
    pdata->name_attr.attr.mode = S_IRUGO;
    pdata->name_attr.show = show_name;
    return device_create_file(dev, &pdata->name_attr);
}

static int __cpuinit create_core_attrs(struct temp_data *tdata,
                       struct device *dev, int attr_no)
{
    int err, i;
    static ssize_t (*const rd_ptr[TOTAL_ATTRS]) (struct device *dev,
            struct device_attribute *devattr, char *buf) = {
            show_label, show_crit_alarm, show_temp, show_tjmax,
            show_ttarget };
    static const char *const names[TOTAL_ATTRS] = {
                    "temp%d_label", "temp%d_crit_alarm",
                    "temp%d_input", "temp%d_crit",
                    "temp%d_max" };

    for (i = 0; i < tdata->attr_size; i++) {
        snprintf(tdata->attr_name[i], CORETEMP_NAME_LENGTH, names[i],
            attr_no);
        sysfs_attr_init(&tdata->sd_attrs[i].dev_attr.attr);
        tdata->sd_attrs[i].dev_attr.attr.name = tdata->attr_name[i];
        tdata->sd_attrs[i].dev_attr.attr.mode = S_IRUGO;
        tdata->sd_attrs[i].dev_attr.show = rd_ptr[i];
        tdata->sd_attrs[i].index = attr_no;
        err = device_create_file(dev, &tdata->sd_attrs[i].dev_attr);
        if (err)
            goto exit_free;
    }
    return 0;

exit_free:
    while (--i >= 0)
        device_remove_file(dev, &tdata->sd_attrs[i].dev_attr);
    return err;
}


static int __cpuinit chk_ucode_version(unsigned int cpu)
{
    struct cpuinfo_x86 *c = &cpu_data(cpu);

    /*
     * Check if we have problem with errata AE18 of Core processors:
     * Readings might stop update when processor visited too deep sleep,
     * fixed for stepping D0 (6EC).
     */
    if (c->x86_model == 0xe && c->x86_mask < 0xc && c->microcode < 0x39) {
        pr_err("Errata AE18 not fixed, update BIOS or "
               "microcode of the CPU!\n");
        return -ENODEV;
    }
    return 0;
}

static struct platform_device __cpuinit *coretemp_get_pdev(unsigned int cpu)
{
    u16 phys_proc_id = TO_PHYS_ID(cpu);
    struct pdev_entry *p;

    mutex_lock(&pdev_list_mutex);

    list_for_each_entry(p, &pdev_list, list)
        if (p->phys_proc_id == phys_proc_id) {
            mutex_unlock(&pdev_list_mutex);
            return p->pdev;
        }

    mutex_unlock(&pdev_list_mutex);
    return NULL;
}

static struct temp_data __cpuinit *init_temp_data(unsigned int cpu,
                          int pkg_flag)
{
    struct temp_data *tdata;

    tdata = kzalloc(sizeof(struct temp_data), GFP_KERNEL);
    if (!tdata)
        return NULL;

    tdata->status_reg = pkg_flag ? MSR_IA32_PACKAGE_THERM_STATUS :
                            MSR_IA32_THERM_STATUS;
    tdata->is_pkg_data = pkg_flag;
    tdata->cpu = cpu;
    tdata->cpu_core_id = TO_CORE_ID(cpu);
    tdata->attr_size = MAX_CORE_ATTRS;
    mutex_init(&tdata->update_lock);
    return tdata;
}

static int __cpuinit create_core_data(struct platform_device *pdev,
                unsigned int cpu, int pkg_flag)
{
    struct temp_data *tdata;
    struct platform_data *pdata = platform_get_drvdata(pdev);
    struct cpuinfo_x86 *c = &cpu_data(cpu);
    u32 eax, edx;
    int err, attr_no;

    /*
     * Find attr number for sysfs:
     * We map the attr number to core id of the CPU
     * The attr number is always core id + 2
     * The Pkgtemp will always show up as temp1_*, if available
     */
    attr_no = pkg_flag ? 1 : TO_ATTR_NO(cpu);

    if (attr_no > MAX_CORE_DATA - 1)
        return -ERANGE;

    /*
     * Provide a single set of attributes for all HT siblings of a core
     * to avoid duplicate sensors (the processor ID and core ID of all
     * HT siblings of a core are the same).
     * Skip if a HT sibling of this core is already registered.
     * This is not an error.
     */
    if (pdata->core_data[attr_no] != NULL)
        return 0;

    tdata = init_temp_data(cpu, pkg_flag);
    if (!tdata)
        return -ENOMEM;

    /* Test if we can access the status register */
    err = rdmsr_safe_on_cpu(cpu, tdata->status_reg, &eax, &edx);
    if (err)
        goto exit_free;

    /* We can access status register. Get Critical Temperature */
    tdata->tjmax = get_tjmax(c, cpu, &pdev->dev);

    /*
     * Read the still undocumented bits 8:15 of IA32_TEMPERATURE_TARGET.
     * The target temperature is available on older CPUs but not in this
     * register. Atoms don't have the register at all.
     */
    if (c->x86_model > 0xe && c->x86_model != 0x1c) {
        err = rdmsr_safe_on_cpu(cpu, MSR_IA32_TEMPERATURE_TARGET,
                    &eax, &edx);
        if (!err) {
            tdata->ttarget
              = tdata->tjmax - ((eax >> 8) & 0xff) * 1000;
            tdata->attr_size++;
        }
    }

    pdata->core_data[attr_no] = tdata;

    /* Create sysfs interfaces */
    err = create_core_attrs(tdata, &pdev->dev, attr_no);
    if (err)
        goto exit_free;

    return 0;
exit_free:
    pdata->core_data[attr_no] = NULL;
    kfree(tdata);
    return err;
}

static void __cpuinit coretemp_add_core(unsigned int cpu, int pkg_flag)
{
    struct platform_device *pdev = coretemp_get_pdev(cpu);
    int err;

    if (!pdev)
        return;

    err = create_core_data(pdev, cpu, pkg_flag);
    if (err)
        dev_err(&pdev->dev, "Adding Core %u failed\n", cpu);
}

static void coretemp_remove_core(struct platform_data *pdata,
                struct device *dev, int indx)
{
    int i;
    struct temp_data *tdata = pdata->core_data[indx];

    /* Remove the sysfs attributes */
    for (i = 0; i < tdata->attr_size; i++)
        device_remove_file(dev, &tdata->sd_attrs[i].dev_attr);

    kfree(pdata->core_data[indx]);
    pdata->core_data[indx] = NULL;
}

static int __devinit coretemp_probe(struct platform_device *pdev)
{
    struct platform_data *pdata;
    int err;

    /* Initialize the per-package data structures */
    pdata = kzalloc(sizeof(struct platform_data), GFP_KERNEL);
    if (!pdata)
        return -ENOMEM;

    err = create_name_attr(pdata, &pdev->dev);
    if (err)
        goto exit_free;

    pdata->phys_proc_id = pdev->id;
    platform_set_drvdata(pdev, pdata);

    pdata->hwmon_dev = hwmon_device_register(&pdev->dev);
    if (IS_ERR(pdata->hwmon_dev)) {
        err = PTR_ERR(pdata->hwmon_dev);
        dev_err(&pdev->dev, "Class registration failed (%d)\n", err);
        goto exit_name;
    }
    return 0;

exit_name:
    device_remove_file(&pdev->dev, &pdata->name_attr);
    platform_set_drvdata(pdev, NULL);
exit_free:
    kfree(pdata);
    return err;
}

static int __devexit coretemp_remove(struct platform_device *pdev)
{
    struct platform_data *pdata = platform_get_drvdata(pdev);
    int i;

    for (i = MAX_CORE_DATA - 1; i >= 0; --i)
        if (pdata->core_data[i])
            coretemp_remove_core(pdata, &pdev->dev, i);

    device_remove_file(&pdev->dev, &pdata->name_attr);
    hwmon_device_unregister(pdata->hwmon_dev);
    platform_set_drvdata(pdev, NULL);
    kfree(pdata);
    return 0;
}

static struct platform_driver coretemp_driver = {
    .driver = {
        .owner = THIS_MODULE,
        .name = DRVNAME,
    },
    .probe = coretemp_probe,
    .remove = __devexit_p(coretemp_remove),
};

static int __cpuinit coretemp_device_add(unsigned int cpu)
{
    int err;
    struct platform_device *pdev;
    struct pdev_entry *pdev_entry;

    mutex_lock(&pdev_list_mutex);

    pdev = platform_device_alloc(DRVNAME, TO_PHYS_ID(cpu));
    if (!pdev) {
        err = -ENOMEM;
        pr_err("Device allocation failed\n");
        goto exit;
    }

    pdev_entry = kzalloc(sizeof(struct pdev_entry), GFP_KERNEL);
    if (!pdev_entry) {
        err = -ENOMEM;
        goto exit_device_put;
    }

    err = platform_device_add(pdev);
    if (err) {
        pr_err("Device addition failed (%d)\n", err);
        goto exit_device_free;
    }

    pdev_entry->pdev = pdev;
    pdev_entry->phys_proc_id = pdev->id;

    list_add_tail(&pdev_entry->list, &pdev_list);
    mutex_unlock(&pdev_list_mutex);

    return 0;

exit_device_free:
    kfree(pdev_entry);
exit_device_put:
    platform_device_put(pdev);
exit:
    mutex_unlock(&pdev_list_mutex);
    return err;
}

static void __cpuinit coretemp_device_remove(unsigned int cpu)
{
    struct pdev_entry *p, *n;
    u16 phys_proc_id = TO_PHYS_ID(cpu);

    mutex_lock(&pdev_list_mutex);
    list_for_each_entry_safe(p, n, &pdev_list, list) {
        if (p->phys_proc_id != phys_proc_id)
            continue;
        platform_device_unregister(p->pdev);
        list_del(&p->list);
        kfree(p);
    }
    mutex_unlock(&pdev_list_mutex);
}

static bool __cpuinit is_any_core_online(struct platform_data *pdata)
{
    int i;

    /* Find online cores, except pkgtemp data */
    for (i = MAX_CORE_DATA - 1; i >= 0; --i) {
        if (pdata->core_data[i] &&
            !pdata->core_data[i]->is_pkg_data) {
            return true;
        }
    }
    return false;
}

static void __cpuinit get_core_online(unsigned int cpu)
{
    struct cpuinfo_x86 *c = &cpu_data(cpu);
    struct platform_device *pdev = coretemp_get_pdev(cpu);
    int err;

    /*
     * CPUID.06H.EAX[0] indicates whether the CPU has thermal
     * sensors. We check this bit only, all the early CPUs
     * without thermal sensors will be filtered out.
     */
    if (!cpu_has(c, X86_FEATURE_DTHERM))
        return;

    if (!pdev) {
        /* Check the microcode version of the CPU */
        if (chk_ucode_version(cpu))
            return;

        /*
         * Alright, we have DTS support.
         * We are bringing the _first_ core in this pkg
         * online. So, initialize per-pkg data structures and
         * then bring this core online.
         */
        err = coretemp_device_add(cpu);
        if (err)
            return;
        /*
         * Check whether pkgtemp support is available.
         * If so, add interfaces for pkgtemp.
         */
        if (cpu_has(c, X86_FEATURE_PTS))
            coretemp_add_core(cpu, 1);
    }
    /*
     * Physical CPU device already exists.
     * So, just add interfaces for this core.
     */
    coretemp_add_core(cpu, 0);
}

static void __cpuinit put_core_offline(unsigned int cpu)
{
    int i, indx;
    struct platform_data *pdata;
    struct platform_device *pdev = coretemp_get_pdev(cpu);

    /* If the physical CPU device does not exist, just return */
    if (!pdev)
        return;

    pdata = platform_get_drvdata(pdev);

    indx = TO_ATTR_NO(cpu);

    /* The core id is too big, just return */
    if (indx > MAX_CORE_DATA - 1)
        return;

    if (pdata->core_data[indx] && pdata->core_data[indx]->cpu == cpu)
        coretemp_remove_core(pdata, &pdev->dev, indx);

    /*
     * If a HT sibling of a core is taken offline, but another HT sibling
     * of the same core is still online, register the alternate sibling.
     * This ensures that exactly one set of attributes is provided as long
     * as at least one HT sibling of a core is online.
     */
    for_each_sibling(i, cpu) {
        if (i != cpu) {
            get_core_online(i);
            /*
             * Display temperature sensor data for one HT sibling
             * per core only, so abort the loop after one such
             * sibling has been found.
             */
            break;
        }
    }
    /*
     * If all cores in this pkg are offline, remove the device.
     * coretemp_device_remove calls unregister_platform_device,
     * which in turn calls coretemp_remove. This removes the
     * pkgtemp entry and does other clean ups.
     */
    if (!is_any_core_online(pdata))
        coretemp_device_remove(cpu);
}

static int __cpuinit coretemp_cpu_callback(struct notifier_block *nfb,
                 unsigned long action, void *hcpu)
{
    unsigned int cpu = (unsigned long) hcpu;

    switch (action) {
    case CPU_ONLINE:
    case CPU_DOWN_FAILED:
        get_core_online(cpu);
        break;
    case CPU_DOWN_PREPARE:
        put_core_offline(cpu);
        break;
    }
    return NOTIFY_OK;
}

static struct notifier_block coretemp_cpu_notifier __refdata = {
    .notifier_call = coretemp_cpu_callback,
};

static const struct x86_cpu_id __initconst coretemp_ids[] = {
    { X86_VENDOR_INTEL, X86_FAMILY_ANY, X86_MODEL_ANY, X86_FEATURE_DTHERM },
    {}
};
MODULE_DEVICE_TABLE(x86cpu, coretemp_ids);

static int __init coretemp_init(void)
{
    int i, err;

    /*
     * CPUID.06H.EAX[0] indicates whether the CPU has thermal
     * sensors. We check this bit only, all the early CPUs
     * without thermal sensors will be filtered out.
     */
    if (!x86_match_cpu(coretemp_ids))
        return -ENODEV;

    err = platform_driver_register(&coretemp_driver);
    if (err)
        goto exit;

    get_online_cpus();
    for_each_online_cpu(i)
        get_core_online(i);

#ifndef CONFIG_HOTPLUG_CPU
    if (list_empty(&pdev_list)) {
        put_online_cpus();
        err = -ENODEV;
        goto exit_driver_unreg;
    }
#endif

    register_hotcpu_notifier(&coretemp_cpu_notifier);
    put_online_cpus();
    return 0;

#ifndef CONFIG_HOTPLUG_CPU
exit_driver_unreg:
    platform_driver_unregister(&coretemp_driver);
#endif
exit:
    return err;
}

static void __exit coretemp_exit(void)
{
    struct pdev_entry *p, *n;

    get_online_cpus();
    unregister_hotcpu_notifier(&coretemp_cpu_notifier);
    mutex_lock(&pdev_list_mutex);
    list_for_each_entry_safe(p, n, &pdev_list, list) {
        platform_device_unregister(p->pdev);
        list_del(&p->list);
        kfree(p);
    }
    mutex_unlock(&pdev_list_mutex);
    put_online_cpus();
    platform_driver_unregister(&coretemp_driver);
}

MODULE_AUTHOR("Rudolf Marek <[email protected]>");
MODULE_DESCRIPTION("Intel Core temperature monitor");
MODULE_LICENSE("GPL");

module_init(coretemp_init)
module_exit(coretemp_exit)