[PATCH] i386: Implement vmi_kmap_atomic_pte

[wrt350n-kernel.git] / arch / i386 / kernel / microcode.c

/*
 *      Intel CPU Microcode Update Driver for Linux
 *
 *      Copyright (C) 2000-2006 Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
 *                    2006      Shaohua Li <shaohua.li@intel.com>
 *
 *      This driver allows to upgrade microcode on Intel processors
 *      belonging to IA-32 family - PentiumPro, Pentium II, 
 *      Pentium III, Xeon, Pentium 4, etc.
 *
 *      Reference: Section 8.10 of Volume III, Intel Pentium 4 Manual, 
 *      Order Number 245472 or free download from:
 *              
 *      http://developer.intel.com/design/pentium4/manuals/245472.htm
 *
 *      For more information, go to http://www.urbanmyth.org/microcode
 *
 *      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; either version
 *      2 of the License, or (at your option) any later version.
 *
 *      1.0     16 Feb 2000, Tigran Aivazian <tigran@sco.com>
 *              Initial release.
 *      1.01    18 Feb 2000, Tigran Aivazian <tigran@sco.com>
 *              Added read() support + cleanups.
 *      1.02    21 Feb 2000, Tigran Aivazian <tigran@sco.com>
 *              Added 'device trimming' support. open(O_WRONLY) zeroes
 *              and frees the saved copy of applied microcode.
 *      1.03    29 Feb 2000, Tigran Aivazian <tigran@sco.com>
 *              Made to use devfs (/dev/cpu/microcode) + cleanups.
 *      1.04    06 Jun 2000, Simon Trimmer <simon@veritas.com>
 *              Added misc device support (now uses both devfs and misc).
 *              Added MICROCODE_IOCFREE ioctl to clear memory.
 *      1.05    09 Jun 2000, Simon Trimmer <simon@veritas.com>
 *              Messages for error cases (non Intel & no suitable microcode).
 *      1.06    03 Aug 2000, Tigran Aivazian <tigran@veritas.com>
 *              Removed ->release(). Removed exclusive open and status bitmap.
 *              Added microcode_rwsem to serialize read()/write()/ioctl().
 *              Removed global kernel lock usage.
 *      1.07    07 Sep 2000, Tigran Aivazian <tigran@veritas.com>
 *              Write 0 to 0x8B msr and then cpuid before reading revision,
 *              so that it works even if there were no update done by the
 *              BIOS. Otherwise, reading from 0x8B gives junk (which happened
 *              to be 0 on my machine which is why it worked even when I
 *              disabled update by the BIOS)
 *              Thanks to Eric W. Biederman <ebiederman@lnxi.com> for the fix.
 *      1.08    11 Dec 2000, Richard Schaal <richard.schaal@intel.com> and
 *                           Tigran Aivazian <tigran@veritas.com>
 *              Intel Pentium 4 processor support and bugfixes.
 *      1.09    30 Oct 2001, Tigran Aivazian <tigran@veritas.com>
 *              Bugfix for HT (Hyper-Threading) enabled processors
 *              whereby processor resources are shared by all logical processors
 *              in a single CPU package.
 *      1.10    28 Feb 2002 Asit K Mallick <asit.k.mallick@intel.com> and
 *              Tigran Aivazian <tigran@veritas.com>,
 *              Serialize updates as required on HT processors due to speculative
 *              nature of implementation.
 *      1.11    22 Mar 2002 Tigran Aivazian <tigran@veritas.com>
 *              Fix the panic when writing zero-length microcode chunk.
 *      1.12    29 Sep 2003 Nitin Kamble <nitin.a.kamble@intel.com>, 
 *              Jun Nakajima <jun.nakajima@intel.com>
 *              Support for the microcode updates in the new format.
 *      1.13    10 Oct 2003 Tigran Aivazian <tigran@veritas.com>
 *              Removed ->read() method and obsoleted MICROCODE_IOCFREE ioctl
 *              because we no longer hold a copy of applied microcode 
 *              in kernel memory.
 *      1.14    25 Jun 2004 Tigran Aivazian <tigran@veritas.com>
 *              Fix sigmatch() macro to handle old CPUs with pf == 0.
 *              Thanks to Stuart Swales for pointing out this bug.
 */

//#define DEBUG /* pr_debug */
#include <linux/capability.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/cpumask.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/miscdevice.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/cpu.h>
#include <linux/firmware.h>
#include <linux/platform_device.h>

#include <asm/msr.h>
#include <asm/uaccess.h>
#include <asm/processor.h>

MODULE_DESCRIPTION("Intel CPU (IA-32) Microcode Update Driver");
MODULE_AUTHOR("Tigran Aivazian <tigran@aivazian.fsnet.co.uk>");
MODULE_LICENSE("GPL");

#define MICROCODE_VERSION       "1.14a"

#define DEFAULT_UCODE_DATASIZE  (2000)    /* 2000 bytes */
#define MC_HEADER_SIZE          (sizeof (microcode_header_t))     /* 48 bytes */
#define DEFAULT_UCODE_TOTALSIZE (DEFAULT_UCODE_DATASIZE + MC_HEADER_SIZE) /* 2048 bytes */
#define EXT_HEADER_SIZE         (sizeof (struct extended_sigtable)) /* 20 bytes */
#define EXT_SIGNATURE_SIZE      (sizeof (struct extended_signature)) /* 12 bytes */
#define DWSIZE                  (sizeof (u32))
#define get_totalsize(mc) \
        (((microcode_t *)mc)->hdr.totalsize ? \
         ((microcode_t *)mc)->hdr.totalsize : DEFAULT_UCODE_TOTALSIZE)
#define get_datasize(mc) \
        (((microcode_t *)mc)->hdr.datasize ? \
         ((microcode_t *)mc)->hdr.datasize : DEFAULT_UCODE_DATASIZE)

#define sigmatch(s1, s2, p1, p2) \
        (((s1) == (s2)) && (((p1) & (p2)) || (((p1) == 0) && ((p2) == 0))))

#define exttable_size(et) ((et)->count * EXT_SIGNATURE_SIZE + EXT_HEADER_SIZE)

/* serialize access to the physical write to MSR 0x79 */
static DEFINE_SPINLOCK(microcode_update_lock);

/* no concurrent ->write()s are allowed on /dev/cpu/microcode */
static DEFINE_MUTEX(microcode_mutex);

static struct ucode_cpu_info {
        int valid;
        unsigned int sig;
        unsigned int pf;
        unsigned int rev;
        microcode_t *mc;
} ucode_cpu_info[NR_CPUS];

static void collect_cpu_info(int cpu_num)
{
        struct cpuinfo_x86 *c = cpu_data + cpu_num;
        struct ucode_cpu_info *uci = ucode_cpu_info + cpu_num;
        unsigned int val[2];

        /* We should bind the task to the CPU */
        BUG_ON(raw_smp_processor_id() != cpu_num);
        uci->pf = uci->rev = 0;
        uci->mc = NULL;
        uci->valid = 1;

        if (c->x86_vendor != X86_VENDOR_INTEL || c->x86 < 6 ||
                cpu_has(c, X86_FEATURE_IA64)) {
                printk(KERN_ERR "microcode: CPU%d not a capable Intel "
                        "processor\n", cpu_num);
                uci->valid = 0;
                return;
        }

        uci->sig = cpuid_eax(0x00000001);

        if ((c->x86_model >= 5) || (c->x86 > 6)) {
                /* get processor flags from MSR 0x17 */
                rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
                uci->pf = 1 << ((val[1] >> 18) & 7);
        }

        wrmsr(MSR_IA32_UCODE_REV, 0, 0);
        /* see notes above for revision 1.07.  Apparent chip bug */
        sync_core();
        /* get the current revision from MSR 0x8B */
        rdmsr(MSR_IA32_UCODE_REV, val[0], uci->rev);
        pr_debug("microcode: collect_cpu_info : sig=0x%x, pf=0x%x, rev=0x%x\n",
                        uci->sig, uci->pf, uci->rev);
}

static inline int microcode_update_match(int cpu_num,
        microcode_header_t *mc_header, int sig, int pf)
{
        struct ucode_cpu_info *uci = ucode_cpu_info + cpu_num;

        if (!sigmatch(sig, uci->sig, pf, uci->pf)
                || mc_header->rev <= uci->rev)
                return 0;
        return 1;
}

static int microcode_sanity_check(void *mc)
{
        microcode_header_t *mc_header = mc;
        struct extended_sigtable *ext_header = NULL;
        struct extended_signature *ext_sig;
        unsigned long total_size, data_size, ext_table_size;
        int sum, orig_sum, ext_sigcount = 0, i;

        total_size = get_totalsize(mc_header);
        data_size = get_datasize(mc_header);
        if (data_size + MC_HEADER_SIZE > total_size) {
                printk(KERN_ERR "microcode: error! "
                        "Bad data size in microcode data file\n");
                return -EINVAL;
        }

        if (mc_header->ldrver != 1 || mc_header->hdrver != 1) {
                printk(KERN_ERR "microcode: error! "
                        "Unknown microcode update format\n");
                return -EINVAL;
        }
        ext_table_size = total_size - (MC_HEADER_SIZE + data_size);
        if (ext_table_size) {
                if ((ext_table_size < EXT_HEADER_SIZE)
                 || ((ext_table_size - EXT_HEADER_SIZE) % EXT_SIGNATURE_SIZE)) {
                        printk(KERN_ERR "microcode: error! "
                                "Small exttable size in microcode data file\n");
                        return -EINVAL;
                }
                ext_header = mc + MC_HEADER_SIZE + data_size;
                if (ext_table_size != exttable_size(ext_header)) {
                        printk(KERN_ERR "microcode: error! "
                                "Bad exttable size in microcode data file\n");
                        return -EFAULT;
                }
                ext_sigcount = ext_header->count;
        }

        /* check extended table checksum */
        if (ext_table_size) {
                int ext_table_sum = 0;
                int *ext_tablep = (int *)ext_header;

                i = ext_table_size / DWSIZE;
                while (i--)
                        ext_table_sum += ext_tablep[i];
                if (ext_table_sum) {
                        printk(KERN_WARNING "microcode: aborting, "
                                "bad extended signature table checksum\n");
                        return -EINVAL;
                }
        }

        /* calculate the checksum */
        orig_sum = 0;
        i = (MC_HEADER_SIZE + data_size) / DWSIZE;
        while (i--)
                orig_sum += ((int *)mc)[i];
        if (orig_sum) {
                printk(KERN_ERR "microcode: aborting, bad checksum\n");
                return -EINVAL;
        }
        if (!ext_table_size)
                return 0;
        /* check extended signature checksum */
        for (i = 0; i < ext_sigcount; i++) {
                ext_sig = (struct extended_signature *)((void *)ext_header
                        + EXT_HEADER_SIZE + EXT_SIGNATURE_SIZE * i);
                sum = orig_sum
                        - (mc_header->sig + mc_header->pf + mc_header->cksum)
                        + (ext_sig->sig + ext_sig->pf + ext_sig->cksum);
                if (sum) {
                        printk(KERN_ERR "microcode: aborting, bad checksum\n");
                        return -EINVAL;
                }
        }
        return 0;
}

/*
 * return 0 - no update found
 * return 1 - found update
 * return < 0 - error
 */
static int get_maching_microcode(void *mc, int cpu)
{
        struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
        microcode_header_t *mc_header = mc;
        struct extended_sigtable *ext_header;
        unsigned long total_size = get_totalsize(mc_header);
        int ext_sigcount, i;
        struct extended_signature *ext_sig;
        void *new_mc;

        if (microcode_update_match(cpu, mc_header,
                        mc_header->sig, mc_header->pf))
                goto find;

        if (total_size <= get_datasize(mc_header) + MC_HEADER_SIZE)
                return 0;

        ext_header = (struct extended_sigtable *)(mc +
                        get_datasize(mc_header) + MC_HEADER_SIZE);
        ext_sigcount = ext_header->count;
        ext_sig = (struct extended_signature *)((void *)ext_header
                        + EXT_HEADER_SIZE);
        for (i = 0; i < ext_sigcount; i++) {
                if (microcode_update_match(cpu, mc_header,
                                ext_sig->sig, ext_sig->pf))
                        goto find;
                ext_sig++;
        }
        return 0;
find:
        pr_debug("microcode: CPU %d found a matching microcode update with"
                " version 0x%x (current=0x%x)\n", cpu, mc_header->rev,uci->rev);
        new_mc = vmalloc(total_size);
        if (!new_mc) {
                printk(KERN_ERR "microcode: error! Can not allocate memory\n");
                return -ENOMEM;
        }

        /* free previous update file */
        vfree(uci->mc);

        memcpy(new_mc, mc, total_size);
        uci->mc = new_mc;
        return 1;
}

static void apply_microcode(int cpu)
{
        unsigned long flags;
        unsigned int val[2];
        int cpu_num = raw_smp_processor_id();
        struct ucode_cpu_info *uci = ucode_cpu_info + cpu_num;

        /* We should bind the task to the CPU */
        BUG_ON(cpu_num != cpu);

        if (uci->mc == NULL)
                return;

        /* serialize access to the physical write to MSR 0x79 */
        spin_lock_irqsave(&microcode_update_lock, flags);          

        /* write microcode via MSR 0x79 */
        wrmsr(MSR_IA32_UCODE_WRITE,
                (unsigned long) uci->mc->bits, 
                (unsigned long) uci->mc->bits >> 16 >> 16);
        wrmsr(MSR_IA32_UCODE_REV, 0, 0);

        /* see notes above for revision 1.07.  Apparent chip bug */
        sync_core();

        /* get the current revision from MSR 0x8B */
        rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);

        spin_unlock_irqrestore(&microcode_update_lock, flags);
        if (val[1] != uci->mc->hdr.rev) {
                printk(KERN_ERR "microcode: CPU%d updated from revision "
                        "0x%x to 0x%x failed\n", cpu_num, uci->rev, val[1]);
                return;
        }
        pr_debug("microcode: CPU%d updated from revision "
               "0x%x to 0x%x, date = %08x \n", 
               cpu_num, uci->rev, val[1], uci->mc->hdr.date);
        uci->rev = val[1];
}

#ifdef CONFIG_MICROCODE_OLD_INTERFACE
static void __user *user_buffer;        /* user area microcode data buffer */
static unsigned int user_buffer_size;   /* it's size */

static long get_next_ucode(void **mc, long offset)
{
        microcode_header_t mc_header;
        unsigned long total_size;

        /* No more data */
        if (offset >= user_buffer_size)
                return 0;
        if (copy_from_user(&mc_header, user_buffer + offset, MC_HEADER_SIZE)) {
                printk(KERN_ERR "microcode: error! Can not read user data\n");
                return -EFAULT;
        }
        total_size = get_totalsize(&mc_header);
        if (offset + total_size > user_buffer_size) {
                printk(KERN_ERR "microcode: error! Bad total size in microcode "
                                "data file\n");
                return -EINVAL;
        }
        *mc = vmalloc(total_size);
        if (!*mc)
                return -ENOMEM;
        if (copy_from_user(*mc, user_buffer + offset, total_size)) {
                printk(KERN_ERR "microcode: error! Can not read user data\n");
                vfree(*mc);
                return -EFAULT;
        }
        return offset + total_size;
}

static int do_microcode_update (void)
{
        long cursor = 0;
        int error = 0;
        void *new_mc = NULL;
        int cpu;
        cpumask_t old;

        old = current->cpus_allowed;

        while ((cursor = get_next_ucode(&new_mc, cursor)) > 0) {
                error = microcode_sanity_check(new_mc);
                if (error)
                        goto out;
                /*
                 * It's possible the data file has multiple matching ucode,
                 * lets keep searching till the latest version
                 */
                for_each_online_cpu(cpu) {
                        struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

                        if (!uci->valid)
                                continue;
                        set_cpus_allowed(current, cpumask_of_cpu(cpu));
                        error = get_maching_microcode(new_mc, cpu);
                        if (error < 0)
                                goto out;
                        if (error == 1)
                                apply_microcode(cpu);
                }
                vfree(new_mc);
        }
out:
        if (cursor > 0)
                vfree(new_mc);
        if (cursor < 0)
                error = cursor;
        set_cpus_allowed(current, old);
        return error;
}

static int microcode_open (struct inode *unused1, struct file *unused2)
{
        return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
}

static ssize_t microcode_write (struct file *file, const char __user *buf, size_t len, loff_t *ppos)
{
        ssize_t ret;

        if ((len >> PAGE_SHIFT) > num_physpages) {
                printk(KERN_ERR "microcode: too much data (max %ld pages)\n", num_physpages);
                return -EINVAL;
        }

        lock_cpu_hotplug();
        mutex_lock(&microcode_mutex);

        user_buffer = (void __user *) buf;
        user_buffer_size = (int) len;

        ret = do_microcode_update();
        if (!ret)
                ret = (ssize_t)len;

        mutex_unlock(&microcode_mutex);
        unlock_cpu_hotplug();

        return ret;
}

static const struct file_operations microcode_fops = {
        .owner          = THIS_MODULE,
        .write          = microcode_write,
        .open           = microcode_open,
};

static struct miscdevice microcode_dev = {
        .minor          = MICROCODE_MINOR,
        .name           = "microcode",
        .fops           = &microcode_fops,
};

static int __init microcode_dev_init (void)
{
        int error;

        error = misc_register(&microcode_dev);
        if (error) {
                printk(KERN_ERR
                        "microcode: can't misc_register on minor=%d\n",
                        MICROCODE_MINOR);
                return error;
        }

        return 0;
}

static void __exit microcode_dev_exit (void)
{
        misc_deregister(&microcode_dev);
}

MODULE_ALIAS_MISCDEV(MICROCODE_MINOR);
#else
#define microcode_dev_init() 0
#define microcode_dev_exit() do { } while(0)
#endif

static long get_next_ucode_from_buffer(void **mc, void *buf,
        unsigned long size, long offset)
{
        microcode_header_t *mc_header;
        unsigned long total_size;

        /* No more data */
        if (offset >= size)
                return 0;
        mc_header = (microcode_header_t *)(buf + offset);
        total_size = get_totalsize(mc_header);

        if (offset + total_size > size) {
                printk(KERN_ERR "microcode: error! Bad data in microcode data file\n");
                return -EINVAL;
        }

        *mc = vmalloc(total_size);
        if (!*mc) {
                printk(KERN_ERR "microcode: error! Can not allocate memory\n");
                return -ENOMEM;
        }
        memcpy(*mc, buf + offset, total_size);
        return offset + total_size;
}

/* fake device for request_firmware */
static struct platform_device *microcode_pdev;

static int cpu_request_microcode(int cpu)
{
        char name[30];
        struct cpuinfo_x86 *c = cpu_data + cpu;
        const struct firmware *firmware;
        void *buf;
        unsigned long size;
        long offset = 0;
        int error;
        void *mc;

        /* We should bind the task to the CPU */
        BUG_ON(cpu != raw_smp_processor_id());
        sprintf(name,"intel-ucode/%02x-%02x-%02x",
                c->x86, c->x86_model, c->x86_mask);
        error = request_firmware(&firmware, name, &microcode_pdev->dev);
        if (error) {
                pr_debug("ucode data file %s load failed\n", name);
                return error;
        }
        buf = (void *)firmware->data;
        size = firmware->size;
        while ((offset = get_next_ucode_from_buffer(&mc, buf, size, offset))
                        > 0) {
                error = microcode_sanity_check(mc);
                if (error)
                        break;
                error = get_maching_microcode(mc, cpu);
                if (error < 0)
                        break;
                /*
                 * It's possible the data file has multiple matching ucode,
                 * lets keep searching till the latest version
                 */
                if (error == 1) {
                        apply_microcode(cpu);
                        error = 0;
                }
                vfree(mc);
        }
        if (offset > 0)
                vfree(mc);
        if (offset < 0)
                error = offset;
        release_firmware(firmware);

        return error;
}

static int apply_microcode_on_cpu(int cpu)
{
        struct cpuinfo_x86 *c = cpu_data + cpu;
        struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
        cpumask_t old;
        unsigned int val[2];
        int err = 0;

        if (!uci->mc)
                return -EINVAL;

        old = current->cpus_allowed;
        set_cpus_allowed(current, cpumask_of_cpu(cpu));

        /* Check if the microcode we have in memory matches the CPU */
        if (c->x86_vendor != X86_VENDOR_INTEL || c->x86 < 6 ||
            cpu_has(c, X86_FEATURE_IA64) || uci->sig != cpuid_eax(0x00000001))
                err = -EINVAL;

        if (!err && ((c->x86_model >= 5) || (c->x86 > 6))) {
                /* get processor flags from MSR 0x17 */
                rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
                if (uci->pf != (1 << ((val[1] >> 18) & 7)))
                        err = -EINVAL;
        }

        if (!err) {
                wrmsr(MSR_IA32_UCODE_REV, 0, 0);
                /* see notes above for revision 1.07.  Apparent chip bug */
                sync_core();
                /* get the current revision from MSR 0x8B */
                rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);
                if (uci->rev != val[1])
                        err = -EINVAL;
        }

        if (!err)
                apply_microcode(cpu);
        else
                printk(KERN_ERR "microcode: Could not apply microcode to CPU%d:"
                        " sig=0x%x, pf=0x%x, rev=0x%x\n",
                        cpu, uci->sig, uci->pf, uci->rev);

        set_cpus_allowed(current, old);
        return err;
}

static void microcode_init_cpu(int cpu)
{
        cpumask_t old;
        struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

        old = current->cpus_allowed;

        set_cpus_allowed(current, cpumask_of_cpu(cpu));
        mutex_lock(&microcode_mutex);
        collect_cpu_info(cpu);
        if (uci->valid && system_state == SYSTEM_RUNNING &&
            !suspend_cpu_hotplug)
                cpu_request_microcode(cpu);
        mutex_unlock(&microcode_mutex);
        set_cpus_allowed(current, old);
}

static void microcode_fini_cpu(int cpu)
{
        struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

        mutex_lock(&microcode_mutex);
        uci->valid = 0;
        vfree(uci->mc);
        uci->mc = NULL;
        mutex_unlock(&microcode_mutex);
}

static ssize_t reload_store(struct sys_device *dev, const char *buf, size_t sz)
{
        struct ucode_cpu_info *uci = ucode_cpu_info + dev->id;
        char *end;
        unsigned long val = simple_strtoul(buf, &end, 0);
        int err = 0;
        int cpu = dev->id;

        if (end == buf)
                return -EINVAL;
        if (val == 1) {
                cpumask_t old;

                old = current->cpus_allowed;

                lock_cpu_hotplug();
                set_cpus_allowed(current, cpumask_of_cpu(cpu));

                mutex_lock(&microcode_mutex);
                if (uci->valid)
                        err = cpu_request_microcode(cpu);
                mutex_unlock(&microcode_mutex);
                unlock_cpu_hotplug();
                set_cpus_allowed(current, old);
        }
        if (err)
                return err;
        return sz;
}

static ssize_t version_show(struct sys_device *dev, char *buf)
{
        struct ucode_cpu_info *uci = ucode_cpu_info + dev->id;

        return sprintf(buf, "0x%x\n", uci->rev);
}

static ssize_t pf_show(struct sys_device *dev, char *buf)
{
        struct ucode_cpu_info *uci = ucode_cpu_info + dev->id;

        return sprintf(buf, "0x%x\n", uci->pf);
}

static SYSDEV_ATTR(reload, 0200, NULL, reload_store);
static SYSDEV_ATTR(version, 0400, version_show, NULL);
static SYSDEV_ATTR(processor_flags, 0400, pf_show, NULL);

static struct attribute *mc_default_attrs[] = {
        &attr_reload.attr,
        &attr_version.attr,
        &attr_processor_flags.attr,
        NULL
};

static struct attribute_group mc_attr_group = {
        .attrs = mc_default_attrs,
        .name = "microcode",
};

static int mc_sysdev_add(struct sys_device *sys_dev)
{
        int err, cpu = sys_dev->id;
        struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

        if (!cpu_online(cpu))
                return 0;

        pr_debug("Microcode:CPU %d added\n", cpu);
        /* If suspend_cpu_hotplug is set, the system is resuming and we should
         * use the data from before the suspend.
         */
        if (suspend_cpu_hotplug) {
                err = apply_microcode_on_cpu(cpu);
                if (err)
                        microcode_fini_cpu(cpu);
        }
        if (!uci->valid)
                memset(uci, 0, sizeof(*uci));

        err = sysfs_create_group(&sys_dev->kobj, &mc_attr_group);
        if (err)
                return err;

        if (!uci->valid)
                microcode_init_cpu(cpu);

        return 0;
}

static int mc_sysdev_remove(struct sys_device *sys_dev)
{
        int cpu = sys_dev->id;

        if (!cpu_online(cpu))
                return 0;
        pr_debug("Microcode:CPU %d removed\n", cpu);
        /* If suspend_cpu_hotplug is set, the system is suspending and we should
         * keep the microcode in memory for the resume.
         */
        if (!suspend_cpu_hotplug)
                microcode_fini_cpu(cpu);
        sysfs_remove_group(&sys_dev->kobj, &mc_attr_group);
        return 0;
}

static int mc_sysdev_resume(struct sys_device *dev)
{
        int cpu = dev->id;

        if (!cpu_online(cpu))
                return 0;
        pr_debug("Microcode:CPU %d resumed\n", cpu);
        /* only CPU 0 will apply ucode here */
        apply_microcode(0);
        return 0;
}

static struct sysdev_driver mc_sysdev_driver = {
        .add = mc_sysdev_add,
        .remove = mc_sysdev_remove,
        .resume = mc_sysdev_resume,
};

static __cpuinit int
mc_cpu_callback(struct notifier_block *nb, unsigned long action, void *hcpu)
{
        unsigned int cpu = (unsigned long)hcpu;
        struct sys_device *sys_dev;

        sys_dev = get_cpu_sysdev(cpu);
        switch (action) {
        case CPU_ONLINE:
        case CPU_DOWN_FAILED:
                mc_sysdev_add(sys_dev);
                break;
        case CPU_DOWN_PREPARE:
                mc_sysdev_remove(sys_dev);
                break;
        }
        return NOTIFY_OK;
}

static struct notifier_block __cpuinitdata mc_cpu_notifier = {
        .notifier_call = mc_cpu_callback,
};

static int __init microcode_init (void)
{
        int error;

        error = microcode_dev_init();
        if (error)
                return error;
        microcode_pdev = platform_device_register_simple("microcode", -1,
                                                         NULL, 0);
        if (IS_ERR(microcode_pdev)) {
                microcode_dev_exit();
                return PTR_ERR(microcode_pdev);
        }

        lock_cpu_hotplug();
        error = sysdev_driver_register(&cpu_sysdev_class, &mc_sysdev_driver);
        unlock_cpu_hotplug();
        if (error) {
                microcode_dev_exit();
                platform_device_unregister(microcode_pdev);
                return error;
        }

        register_hotcpu_notifier(&mc_cpu_notifier);

        printk(KERN_INFO 
                "IA-32 Microcode Update Driver: v" MICROCODE_VERSION " <tigran@aivazian.fsnet.co.uk>\n");
        return 0;
}

static void __exit microcode_exit (void)
{
        microcode_dev_exit();

        unregister_hotcpu_notifier(&mc_cpu_notifier);

        lock_cpu_hotplug();
        sysdev_driver_unregister(&cpu_sysdev_class, &mc_sysdev_driver);
        unlock_cpu_hotplug();

        platform_device_unregister(microcode_pdev);
}

module_init(microcode_init)
module_exit(microcode_exit)