// SPDX-License-Identifier: GPL-2.0-only
/*
 * coretemp.c - Linux kernel module for hardware monitoring
 *
 * Copyright (C) 2007 Rudolf Marek <r.marek@assembler.cz>
 *
 * Inspired from many hwmon drivers
 */

#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/smp.h>
#include <linux/moduleparam.h>
#include <linux/pci.h>
#include <asm/msr.h>
#include <asm/processor.h>
#include <asm/cpu_device_id.h>
#include <linux/sched/isolation.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 NUM_REAL_CORES          512     /* Number of Real cores per cpu */
#define CORETEMP_NAME_LENGTH    28      /* String Length of attrs */

enum coretemp_attr_index {
        ATTR_LABEL,
        ATTR_CRIT_ALARM,
        ATTR_TEMP,
        ATTR_TJMAX,
        ATTR_TTARGET,
        MAX_CORE_ATTRS = ATTR_TJMAX + 1,        /* Maximum no of basic attrs */
        TOTAL_ATTRS = ATTR_TTARGET + 1          /* Maximum no of possible attrs */
};

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

/*
 * Per-Core Temperature Data
 * @tjmax: The static tjmax value when tjmax cannot be retrieved from
 *              IA32_TEMPERATURE_TARGET MSR.
 * @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.
 */
struct temp_data {
        int temp;
        int tjmax;
        unsigned long last_updated;
        unsigned int cpu;
        int index;
        u32 cpu_core_id;
        u32 status_reg;
        int attr_size;
        struct device_attribute sd_attrs[TOTAL_ATTRS];
        char attr_name[TOTAL_ATTRS][CORETEMP_NAME_LENGTH];
        struct attribute *attrs[TOTAL_ATTRS + 1];
        struct attribute_group attr_group;
        struct mutex update_lock;
};

/* Platform Data per Physical CPU */
struct platform_data {
        struct device           *hwmon_dev;
        u16                     pkg_id;
        int                     nr_cores;
        struct ida              ida;
        struct cpumask          cpumask;
        struct temp_data        *pkg_data;
        struct temp_data        **core_data;
        struct device_attribute name_attr;
};

struct tjmax_pci {
        unsigned int device;
        int tjmax;
};

static const struct tjmax_pci tjmax_pci_table[] = {
        { 0x0708, 110000 },     /* CE41x0 (Sodaville ) */
        { 0x0c72, 102000 },     /* Atom S1240 (Centerton) */
        { 0x0c73, 95000 },      /* Atom S1220 (Centerton) */
        { 0x0c75, 95000 },      /* Atom S1260 (Centerton) */
};

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

static const struct tjmax tjmax_table[] = {
        { "CPU  230", 100000 },         /* Model 0x1c, stepping 2       */
        { "CPU  330", 125000 },         /* Model 0x1c, stepping 2       */
};

struct tjmax_model {
        u32 vfm;
        u8 stepping_mask;
        int tjmax;
};

#define ANY 0xff

static const struct tjmax_model tjmax_model_table[] = {
        { INTEL_ATOM_BONNELL,         10,  100000 },    /* D4xx, K4xx, N4xx, D5xx, K5xx, N5xx */
        { INTEL_ATOM_BONNELL,         ANY, 90000 },     /* Z5xx, N2xx, possibly others
                                                         * Note: Also matches 230 and 330,
                                                         * which are covered by tjmax_table
                                                         */
        { INTEL_ATOM_BONNELL_MID,     ANY, 90000 },     /* Atom Tunnel Creek (Exx), Lincroft (Z6xx)
                                                         * Note: TjMax for E6xxT is 110C, but CPU type
                                                         * is undetectable by software
                                                         */
        { INTEL_ATOM_SALTWELL_MID,    ANY, 90000 },     /* Atom Medfield (Z2460) */
        { INTEL_ATOM_SALTWELL_TABLET, ANY, 90000 },     /* Atom Clover Trail/Cloverview (Z27x0) */
        { INTEL_ATOM_SALTWELL,        ANY, 100000 },    /* Atom Cedar Trail/Cedarview (N2xxx, D2xxx)
                                                         * Also matches S12x0 (stepping 9), covered by
                                                         * PCI table
                                                         */
        { INTEL_ATOM_SILVERMONT,      9, 110000 },      /* Atom Bay Trail E38xx (embedded) */
        { INTEL_ATOM_SILVERMONT,      ANY, 90000 },     /* Atom Bay Trail Z37xx (tablet) */
        { INTEL_ATOM_SILVERMONT_MID,  ANY, 90000 },     /* Atom Merrifield (Z34xx) */
        { INTEL_ATOM_SILVERMONT_MID2, ANY, 90000 },     /* Atom Moorefield (Z35xx) */
        { INTEL_ATOM_AIRMONT,         ANY, 90000 },     /* Atom Cherry Trail (Z8xxx) */
        { INTEL_ATOM_GOLDMONT,        ANY, 105000 },    /* Atom Apollo Lake (J3xxx, N3xxx, E39xx) */
        { INTEL_ATOM_GOLDMONT_PLUS,   ANY, 105000 },    /* Atom Gemini Lake (J4xxx, N4xxx, N5xxx) */
        { INTEL_ATOM_TREMONT,         ANY, 105000 },    /* Atom Elkhart Lake */
        { INTEL_ATOM_TREMONT_L,       ANY, 105000 },    /* Atom Jasper Lake */
};

static bool is_pkg_temp_data(struct temp_data *tdata)
{
        return tdata->index < 0;
}

static int 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;
        int i;
        u16 devfn = PCI_DEVFN(0, 0);
        struct pci_dev *host_bridge = pci_get_domain_bus_and_slot(0, 0, devfn);

        /*
         * Explicit tjmax table entries override heuristics.
         * First try PCI host bridge IDs, followed by model ID strings
         * and model/stepping information.
         */
        if (host_bridge && host_bridge->vendor == PCI_VENDOR_ID_INTEL) {
                for (i = 0; i < ARRAY_SIZE(tjmax_pci_table); i++) {
                        if (host_bridge->device == tjmax_pci_table[i].device) {
                                pci_dev_put(host_bridge);
                                return tjmax_pci_table[i].tjmax;
                        }
                }
        }
        pci_dev_put(host_bridge);

        /*
         * This is literally looking for "CPU  XXX" in the model string.
         * Not checking it against the model as well. Just purely a
         * string search.
         */
        for (i = 0; i < ARRAY_SIZE(tjmax_table); i++) {
                if (strstr(c->x86_model_id, tjmax_table[i].id))
                        return tjmax_table[i].tjmax;
        }

        for (i = 0; i < ARRAY_SIZE(tjmax_model_table); i++) {
                const struct tjmax_model *tm = &tjmax_model_table[i];
                if (c->x86_vfm == tm->vfm &&
                    (tm->stepping_mask == ANY ||
                     tm->stepping_mask == c->x86_stepping))
                        return tm->tjmax;
        }

        /* Early chips have no MSR for TjMax */

        if (c->x86_vfm == INTEL_CORE2_MEROM && c->x86_stepping < 4)
                usemsr_ee = 0;

        if (c->x86_vfm > INTEL_CORE_YONAH && 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_vfm < INTEL_CORE2_PENRYN &&
                           !(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_vfm == INTEL_CORE2_PENRYN &&
                            (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 get_tjmax(struct temp_data *tdata, struct device *dev)
{
        struct cpuinfo_x86 *c = &cpu_data(tdata->cpu);
        int err;
        u32 eax, edx;
        u32 val;

        /* use static tjmax once it is set */
        if (tdata->tjmax)
                return tdata->tjmax;

        /*
         * A new feature of current Intel(R) processors, the
         * IA32_TEMPERATURE_TARGET contains the TjMax value
         */
        err = rdmsr_safe_on_cpu(tdata->cpu, MSR_IA32_TEMPERATURE_TARGET, &eax, &edx);
        if (err) {
                dev_warn_once(dev, "Unable to read TjMax from CPU %u\n", tdata->cpu);
        } else {
                val = (eax >> 16) & 0xff;
                if (val)
                        return val * 1000;
        }

        if (force_tjmax) {
                dev_notice(dev, "TjMax forced to %d degrees C by user\n",
                           force_tjmax);
                tdata->tjmax = force_tjmax * 1000;
        } else {
                /*
                 * An assumption is made for early CPUs and unreadable MSR.
                 * NOTE: the calculated value may not be correct.
                 */
                tdata->tjmax = adjust_tjmax(c, tdata->cpu, dev);
        }
        return tdata->tjmax;
}

static int get_ttarget(struct temp_data *tdata, struct device *dev)
{
        u32 eax, edx;
        int tjmax, ttarget_offset, ret;

        /*
         * ttarget is valid only if tjmax can be retrieved from
         * MSR_IA32_TEMPERATURE_TARGET
         */
        if (tdata->tjmax)
                return -ENODEV;

        ret = rdmsr_safe_on_cpu(tdata->cpu, MSR_IA32_TEMPERATURE_TARGET, &eax, &edx);
        if (ret)
                return ret;

        tjmax = (eax >> 16) & 0xff;

        /* Read the still undocumented bits 8:15 of IA32_TEMPERATURE_TARGET. */
        ttarget_offset = (eax >> 8) & 0xff;

        return (tjmax - ttarget_offset) * 1000;
}

/* Keep track of how many zone pointers we allocated in init() */
static int max_zones __read_mostly;
/* Array of zone pointers. Serialized by cpu hotplug lock */
static struct platform_device **zone_devices;

static ssize_t show_label(struct device *dev,
                                struct device_attribute *devattr, char *buf)
{
        struct platform_data *pdata = dev_get_drvdata(dev);
        struct temp_data *tdata = container_of(devattr, struct temp_data, sd_attrs[ATTR_LABEL]);

        if (is_pkg_temp_data(tdata))
                return sprintf(buf, "Package id %u\n", pdata->pkg_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 temp_data *tdata = container_of(devattr, struct temp_data,
                                                sd_attrs[ATTR_CRIT_ALARM]);

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

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

static ssize_t show_tjmax(struct device *dev,
                        struct device_attribute *devattr, char *buf)
{
        struct temp_data *tdata = container_of(devattr, struct temp_data, sd_attrs[ATTR_TJMAX]);
        int tjmax;

        mutex_lock(&tdata->update_lock);
        tjmax = get_tjmax(tdata, dev);
        mutex_unlock(&tdata->update_lock);

        return sprintf(buf, "%d\n", tjmax);
}

static ssize_t show_ttarget(struct device *dev,
                                struct device_attribute *devattr, char *buf)
{
        struct temp_data *tdata = container_of(devattr, struct temp_data, sd_attrs[ATTR_TTARGET]);
        int ttarget;

        mutex_lock(&tdata->update_lock);
        ttarget = get_ttarget(tdata, dev);
        mutex_unlock(&tdata->update_lock);

        if (ttarget < 0)
                return ttarget;
        return sprintf(buf, "%d\n", ttarget);
}

static ssize_t show_temp(struct device *dev,
                        struct device_attribute *devattr, char *buf)
{
        u32 eax, edx;
        struct temp_data *tdata = container_of(devattr, struct temp_data, sd_attrs[ATTR_TEMP]);
        int tjmax;

        mutex_lock(&tdata->update_lock);

        tjmax = get_tjmax(tdata, dev);
        /* Check whether the time interval has elapsed */
        if (time_after(jiffies, tdata->last_updated + HZ)) {
                rdmsr_on_cpu(tdata->cpu, tdata->status_reg, &eax, &edx);
                /*
                 * Ignore the valid bit. In all observed cases the register
                 * value is either low or zero if the valid bit is 0.
                 * Return it instead of reporting an error which doesn't
                 * really help at all.
                 */
                tdata->temp = tjmax - ((eax >> 16) & 0xff) * 1000;
                tdata->last_updated = jiffies;
        }

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

static int create_core_attrs(struct temp_data *tdata, struct device *dev)
{
        int 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 suffixes[TOTAL_ATTRS] = {
                "label", "crit_alarm", "input", "crit", "max"
        };

        for (i = 0; i < tdata->attr_size; i++) {
                /*
                 * 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
                 */
                int attr_no = is_pkg_temp_data(tdata) ? 1 : tdata->cpu_core_id + 2;

                snprintf(tdata->attr_name[i], CORETEMP_NAME_LENGTH,
                         "temp%d_%s", attr_no, suffixes[i]);
                sysfs_attr_init(&tdata->sd_attrs[i].attr);
                tdata->sd_attrs[i].attr.name = tdata->attr_name[i];
                tdata->sd_attrs[i].attr.mode = 0444;
                tdata->sd_attrs[i].show = rd_ptr[i];
                tdata->attrs[i] = &tdata->sd_attrs[i].attr;
        }
        tdata->attr_group.attrs = tdata->attrs;
        return sysfs_create_group(&dev->kobj, &tdata->attr_group);
}


static int 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_vfm == INTEL_CORE_YONAH && c->x86_stepping < 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 *coretemp_get_pdev(unsigned int cpu)
{
        int id = topology_logical_die_id(cpu);

        if (id >= 0 && id < max_zones)
                return zone_devices[id];
        return NULL;
}

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

        if (!pdata->core_data) {
                /*
                 * TODO:
                 * The information of actual possible cores in a package is broken for now.
                 * Will replace hardcoded NUM_REAL_CORES with actual per package core count
                 * when this information becomes available.
                 */
                pdata->nr_cores = NUM_REAL_CORES;
                pdata->core_data = kzalloc_objs(struct temp_data *,
                                                pdata->nr_cores);
                if (!pdata->core_data)
                        return NULL;
        }

        tdata = kzalloc_obj(struct temp_data);
        if (!tdata)
                return NULL;

        if (pkg_flag) {
                pdata->pkg_data = tdata;
                /* Use tdata->index as indicator of package temp data */
                tdata->index = -1;
        } else {
                tdata->index = ida_alloc_max(&pdata->ida, pdata->nr_cores - 1, GFP_KERNEL);
                if (tdata->index < 0) {
                        kfree(tdata);
                        return NULL;
                }
                pdata->core_data[tdata->index] = tdata;
        }

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

static void destroy_temp_data(struct platform_data *pdata, struct temp_data *tdata)
{
        if (is_pkg_temp_data(tdata)) {
                pdata->pkg_data = NULL;
                kfree(pdata->core_data);
                pdata->core_data = NULL;
                pdata->nr_cores = 0;
        } else {
                pdata->core_data[tdata->index] = NULL;
                ida_free(&pdata->ida, tdata->index);
        }
        kfree(tdata);
}

static struct temp_data *get_temp_data(struct platform_data *pdata, int cpu)
{
        int i;

        /* cpu < 0 means get pkg temp_data */
        if (cpu < 0)
                return pdata->pkg_data;

        for (i = 0; i < pdata->nr_cores; i++) {
                if (pdata->core_data[i] &&
                    pdata->core_data[i]->cpu_core_id == topology_core_id(cpu))
                        return pdata->core_data[i];
        }
        return NULL;
}

static int 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;

        if (!housekeeping_cpu(cpu, HK_TYPE_MISC))
                return 0;

        tdata = init_temp_data(pdata, 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 err;

        /* Make sure tdata->tjmax is a valid indicator for dynamic/static tjmax */
        get_tjmax(tdata, &pdev->dev);

        /*
         * The target temperature is available on older CPUs but not in the
         * MSR_IA32_TEMPERATURE_TARGET register. Atoms don't have the register
         * at all.
         */
        if (c->x86_vfm > INTEL_CORE_YONAH && c->x86_vfm != INTEL_ATOM_BONNELL)
                if (get_ttarget(tdata, &pdev->dev) >= 0)
                        tdata->attr_size++;

        /* Create sysfs interfaces */
        err = create_core_attrs(tdata, pdata->hwmon_dev);
        if (err)
                goto err;

        return 0;

err:
        destroy_temp_data(pdata, tdata);
        return err;
}

static void
coretemp_add_core(struct platform_device *pdev, unsigned int cpu, int pkg_flag)
{
        if (create_core_data(pdev, cpu, pkg_flag))
                dev_err(&pdev->dev, "Adding Core %u failed\n", cpu);
}

static void coretemp_remove_core(struct platform_data *pdata, struct temp_data *tdata)
{
        /* if we errored on add then this is already gone */
        if (!tdata)
                return;

        /* Remove the sysfs attributes */
        sysfs_remove_group(&pdata->hwmon_dev->kobj, &tdata->attr_group);

        destroy_temp_data(pdata, tdata);
}

static int coretemp_device_add(int zoneid)
{
        struct platform_device *pdev;
        struct platform_data *pdata;
        int err;

        /* Initialize the per-zone data structures */
        pdata = kzalloc_obj(*pdata);
        if (!pdata)
                return -ENOMEM;

        pdata->pkg_id = zoneid;
        ida_init(&pdata->ida);

        pdev = platform_device_alloc(DRVNAME, zoneid);
        if (!pdev) {
                err = -ENOMEM;
                goto err_free_pdata;
        }

        err = platform_device_add(pdev);
        if (err)
                goto err_put_dev;

        platform_set_drvdata(pdev, pdata);
        zone_devices[zoneid] = pdev;
        return 0;

err_put_dev:
        platform_device_put(pdev);
err_free_pdata:
        kfree(pdata);
        return err;
}

static void coretemp_device_remove(int zoneid)
{
        struct platform_device *pdev = zone_devices[zoneid];
        struct platform_data *pdata = platform_get_drvdata(pdev);

        ida_destroy(&pdata->ida);
        kfree(pdata);
        platform_device_unregister(pdev);
}

static int coretemp_cpu_online(unsigned int cpu)
{
        struct platform_device *pdev = coretemp_get_pdev(cpu);
        struct cpuinfo_x86 *c = &cpu_data(cpu);
        struct platform_data *pdata;

        /*
         * Don't execute this on resume as the offline callback did
         * not get executed on suspend.
         */
        if (cpuhp_tasks_frozen)
                return 0;

        /*
         * 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 -ENODEV;

        pdata = platform_get_drvdata(pdev);
        if (!pdata->hwmon_dev) {
                struct device *hwmon;

                /* Check the microcode version of the CPU */
                if (chk_ucode_version(cpu))
                        return -EINVAL;

                /*
                 * 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.
                 */
                hwmon = hwmon_device_register_with_groups(&pdev->dev, DRVNAME,
                                                          pdata, NULL);
                if (IS_ERR(hwmon))
                        return PTR_ERR(hwmon);
                pdata->hwmon_dev = hwmon;

                /*
                 * Check whether pkgtemp support is available.
                 * If so, add interfaces for pkgtemp.
                 */
                if (cpu_has(c, X86_FEATURE_PTS))
                        coretemp_add_core(pdev, cpu, 1);
        }

        /*
         * Check whether a thread sibling is already online. If not add the
         * interface for this CPU core.
         */
        if (!cpumask_intersects(&pdata->cpumask, topology_sibling_cpumask(cpu)))
                coretemp_add_core(pdev, cpu, 0);

        cpumask_set_cpu(cpu, &pdata->cpumask);
        return 0;
}

static int coretemp_cpu_offline(unsigned int cpu)
{
        struct platform_device *pdev = coretemp_get_pdev(cpu);
        struct platform_data *pd;
        struct temp_data *tdata;
        int target;

        /* No need to tear down any interfaces for suspend */
        if (cpuhp_tasks_frozen)
                return 0;

        /* If the physical CPU device does not exist, just return */
        pd = platform_get_drvdata(pdev);
        if (!pd->hwmon_dev)
                return 0;

        tdata = get_temp_data(pd, cpu);

        cpumask_clear_cpu(cpu, &pd->cpumask);

        /*
         * If this is the last thread sibling, remove the CPU core
         * interface, If there is still a sibling online, transfer the
         * target cpu of that core interface to it.
         */
        target = cpumask_any_and(&pd->cpumask, topology_sibling_cpumask(cpu));
        if (target >= nr_cpu_ids) {
                coretemp_remove_core(pd, tdata);
        } else if (tdata && tdata->cpu == cpu) {
                mutex_lock(&tdata->update_lock);
                tdata->cpu = target;
                mutex_unlock(&tdata->update_lock);
        }

        /*
         * If all cores in this pkg are offline, remove the interface.
         */
        tdata = get_temp_data(pd, -1);
        if (cpumask_empty(&pd->cpumask)) {
                if (tdata)
                        coretemp_remove_core(pd, tdata);
                hwmon_device_unregister(pd->hwmon_dev);
                pd->hwmon_dev = NULL;
                return 0;
        }

        /*
         * Check whether this core is the target for the package
         * interface. We need to assign it to some other cpu.
         */
        if (tdata && tdata->cpu == cpu) {
                target = cpumask_first(&pd->cpumask);
                mutex_lock(&tdata->update_lock);
                tdata->cpu = target;
                mutex_unlock(&tdata->update_lock);
        }
        return 0;
}
static const struct x86_cpu_id __initconst coretemp_ids[] = {
        X86_MATCH_VENDOR_FEATURE(INTEL, X86_FEATURE_DTHERM, NULL),
        {}
};
MODULE_DEVICE_TABLE(x86cpu, coretemp_ids);

static enum cpuhp_state coretemp_hp_online;

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. This
         * includes all the Family 5 and Family 15 (Pentium 4)
         * models, since they never set the CPUID bit.
         */
        if (!x86_match_cpu(coretemp_ids))
                return -ENODEV;

        max_zones = topology_max_packages() * topology_max_dies_per_package();
        zone_devices = kzalloc_objs(struct platform_device *, max_zones);
        if (!zone_devices)
                return -ENOMEM;

        for (i = 0; i < max_zones; i++) {
                err = coretemp_device_add(i);
                if (err)
                        goto outzone;
        }

        err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "hwmon/coretemp:online",
                                coretemp_cpu_online, coretemp_cpu_offline);
        if (err < 0)
                goto outzone;
        coretemp_hp_online = err;
        return 0;

outzone:
        while (i--)
                coretemp_device_remove(i);
        kfree(zone_devices);
        return err;
}
module_init(coretemp_init)

static void __exit coretemp_exit(void)
{
        int i;

        cpuhp_remove_state(coretemp_hp_online);
        for (i = 0; i < max_zones; i++)
                coretemp_device_remove(i);
        kfree(zone_devices);
}
module_exit(coretemp_exit)

MODULE_AUTHOR("Rudolf Marek <r.marek@assembler.cz>");
MODULE_DESCRIPTION("Intel Core temperature monitor");
MODULE_LICENSE("GPL");