root/drivers/hwmon/via-cputemp.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * via-cputemp.c - Driver for VIA CPU core temperature monitoring
 * Copyright (C) 2009 VIA Technologies, Inc.
 *
 * based on existing coretemp.c, which is
 *
 * Copyright (C) 2007 Rudolf Marek <r.marek@assembler.cz>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/hwmon.h>
#include <linux/hwmon-vid.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 <asm/msr.h>
#include <asm/processor.h>
#include <asm/cpu_device_id.h>

#define DRVNAME "via_cputemp"

enum { SHOW_TEMP, SHOW_LABEL, SHOW_NAME };

/*
 * Functions declaration
 */

struct via_cputemp_data {
        struct device *hwmon_dev;
        const char *name;
        u8 vrm;
        u32 id;
        u32 msr_temp;
        u32 msr_vid;
};

/*
 * Sysfs stuff
 */

static ssize_t name_show(struct device *dev, struct device_attribute *devattr,
                         char *buf)
{
        int ret;
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct via_cputemp_data *data = dev_get_drvdata(dev);

        if (attr->index == SHOW_NAME)
                ret = sprintf(buf, "%s\n", data->name);
        else    /* show label */
                ret = sprintf(buf, "Core %d\n", data->id);
        return ret;
}

static ssize_t temp_show(struct device *dev, struct device_attribute *devattr,
                         char *buf)
{
        struct via_cputemp_data *data = dev_get_drvdata(dev);
        u32 eax, edx;
        int err;

        err = rdmsr_safe_on_cpu(data->id, data->msr_temp, &eax, &edx);
        if (err)
                return -EAGAIN;

        return sprintf(buf, "%lu\n", ((unsigned long)eax & 0xffffff) * 1000);
}

static ssize_t cpu0_vid_show(struct device *dev,
                             struct device_attribute *devattr, char *buf)
{
        struct via_cputemp_data *data = dev_get_drvdata(dev);
        u32 eax, edx;
        int err;

        err = rdmsr_safe_on_cpu(data->id, data->msr_vid, &eax, &edx);
        if (err)
                return -EAGAIN;

        return sprintf(buf, "%d\n", vid_from_reg(~edx & 0x7f, data->vrm));
}

static SENSOR_DEVICE_ATTR_RO(temp1_input, temp, SHOW_TEMP);
static SENSOR_DEVICE_ATTR_RO(temp1_label, name, SHOW_LABEL);
static SENSOR_DEVICE_ATTR_RO(name, name, SHOW_NAME);

static struct attribute *via_cputemp_attributes[] = {
        &sensor_dev_attr_name.dev_attr.attr,
        &sensor_dev_attr_temp1_label.dev_attr.attr,
        &sensor_dev_attr_temp1_input.dev_attr.attr,
        NULL
};

static const struct attribute_group via_cputemp_group = {
        .attrs = via_cputemp_attributes,
};

/* Optional attributes */
static DEVICE_ATTR_RO(cpu0_vid);

static int via_cputemp_probe(struct platform_device *pdev)
{
        struct via_cputemp_data *data;
        struct cpuinfo_x86 *c = &cpu_data(pdev->id);
        int err;
        u32 eax, edx;

        data = devm_kzalloc(&pdev->dev, sizeof(struct via_cputemp_data),
                            GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->id = pdev->id;
        data->name = "via_cputemp";

        if (c->x86 == 7) {
                data->msr_temp = 0x1423;
        } else {
                switch (c->x86_model) {
                case 0xA:
                        /* C7 A */
                case 0xD:
                        /* C7 D */
                        data->msr_temp = 0x1169;
                        data->msr_vid = 0x198;
                        break;
                case 0xF:
                        /* Nano */
                        data->msr_temp = 0x1423;
                        break;
                default:
                        return -ENODEV;
                }
        }

        /* test if we can access the TEMPERATURE MSR */
        err = rdmsr_safe_on_cpu(data->id, data->msr_temp, &eax, &edx);
        if (err) {
                dev_err(&pdev->dev,
                        "Unable to access TEMPERATURE MSR, giving up\n");
                return err;
        }

        platform_set_drvdata(pdev, data);

        err = sysfs_create_group(&pdev->dev.kobj, &via_cputemp_group);
        if (err)
                return err;

        if (data->msr_vid)
                data->vrm = vid_which_vrm();

        if (data->vrm) {
                err = device_create_file(&pdev->dev, &dev_attr_cpu0_vid);
                if (err)
                        goto exit_remove;
        }

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

        return 0;

exit_remove:
        if (data->vrm)
                device_remove_file(&pdev->dev, &dev_attr_cpu0_vid);
        sysfs_remove_group(&pdev->dev.kobj, &via_cputemp_group);
        return err;
}

static void via_cputemp_remove(struct platform_device *pdev)
{
        struct via_cputemp_data *data = platform_get_drvdata(pdev);

        hwmon_device_unregister(data->hwmon_dev);
        if (data->vrm)
                device_remove_file(&pdev->dev, &dev_attr_cpu0_vid);
        sysfs_remove_group(&pdev->dev.kobj, &via_cputemp_group);
}

static struct platform_driver via_cputemp_driver = {
        .driver = {
                .name = DRVNAME,
        },
        .probe = via_cputemp_probe,
        .remove = via_cputemp_remove,
};

struct pdev_entry {
        struct list_head list;
        struct platform_device *pdev;
        unsigned int cpu;
};

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

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

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

        pdev_entry = kzalloc_obj(struct pdev_entry);
        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->cpu = cpu;
        mutex_lock(&pdev_list_mutex);
        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:
        return err;
}

static int via_cputemp_down_prep(unsigned int cpu)
{
        struct pdev_entry *p;

        mutex_lock(&pdev_list_mutex);
        list_for_each_entry(p, &pdev_list, list) {
                if (p->cpu == cpu) {
                        platform_device_unregister(p->pdev);
                        list_del(&p->list);
                        mutex_unlock(&pdev_list_mutex);
                        kfree(p);
                        return 0;
                }
        }
        mutex_unlock(&pdev_list_mutex);
        return 0;
}

static const struct x86_cpu_id __initconst cputemp_ids[] = {
        X86_MATCH_VENDOR_FAM_MODEL(CENTAUR, 6, X86_CENTAUR_FAM6_C7_A,   NULL),
        X86_MATCH_VENDOR_FAM_MODEL(CENTAUR, 6, X86_CENTAUR_FAM6_C7_D,   NULL),
        X86_MATCH_VENDOR_FAM_MODEL(CENTAUR, 6, X86_CENTAUR_FAM6_NANO,   NULL),
        X86_MATCH_VENDOR_FAM_MODEL(CENTAUR, 7, X86_MODEL_ANY,           NULL),
        {}
};
MODULE_DEVICE_TABLE(x86cpu, cputemp_ids);

static enum cpuhp_state via_temp_online;

static int __init via_cputemp_init(void)
{
        int err;

        if (!x86_match_cpu(cputemp_ids))
                return -ENODEV;

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

        err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "hwmon/via:online",
                                via_cputemp_online, via_cputemp_down_prep);
        if (err < 0)
                goto exit_driver_unreg;
        via_temp_online = err;

#ifndef CONFIG_HOTPLUG_CPU
        if (list_empty(&pdev_list)) {
                err = -ENODEV;
                goto exit_hp_unreg;
        }
#endif
        return 0;

#ifndef CONFIG_HOTPLUG_CPU
exit_hp_unreg:
        cpuhp_remove_state_nocalls(via_temp_online);
#endif
exit_driver_unreg:
        platform_driver_unregister(&via_cputemp_driver);
exit:
        return err;
}

static void __exit via_cputemp_exit(void)
{
        cpuhp_remove_state(via_temp_online);
        platform_driver_unregister(&via_cputemp_driver);
}

MODULE_AUTHOR("Harald Welte <HaraldWelte@viatech.com>");
MODULE_DESCRIPTION("VIA CPU temperature monitor");
MODULE_LICENSE("GPL");

module_init(via_cputemp_init)
module_exit(via_cputemp_exit)