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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/i386/kernel/cpu/mtrr/main.c
downloadconfigs-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/i386/kernel/cpu/mtrr/main.c')
-rw-r--r--arch/i386/kernel/cpu/mtrr/main.c693
1 files changed, 693 insertions, 0 deletions
diff --git a/arch/i386/kernel/cpu/mtrr/main.c b/arch/i386/kernel/cpu/mtrr/main.c
new file mode 100644
index 00000000000..8f67b490a7f
--- /dev/null
+++ b/arch/i386/kernel/cpu/mtrr/main.c
@@ -0,0 +1,693 @@
+/* Generic MTRR (Memory Type Range Register) driver.
+
+ Copyright (C) 1997-2000 Richard Gooch
+ Copyright (c) 2002 Patrick Mochel
+
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Library General Public
+ License as published by the Free Software Foundation; either
+ version 2 of the License, or (at your option) any later version.
+
+ This library 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
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public
+ License along with this library; if not, write to the Free
+ Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+ Richard Gooch may be reached by email at rgooch@atnf.csiro.au
+ The postal address is:
+ Richard Gooch, c/o ATNF, P. O. Box 76, Epping, N.S.W., 2121, Australia.
+
+ Source: "Pentium Pro Family Developer's Manual, Volume 3:
+ Operating System Writer's Guide" (Intel document number 242692),
+ section 11.11.7
+
+ This was cleaned and made readable by Patrick Mochel <mochel@osdl.org>
+ on 6-7 March 2002.
+ Source: Intel Architecture Software Developers Manual, Volume 3:
+ System Programming Guide; Section 9.11. (1997 edition - PPro).
+*/
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/pci.h>
+#include <linux/smp.h>
+#include <linux/cpu.h>
+
+#include <asm/mtrr.h>
+
+#include <asm/uaccess.h>
+#include <asm/processor.h>
+#include <asm/msr.h>
+#include "mtrr.h"
+
+#define MTRR_VERSION "2.0 (20020519)"
+
+u32 num_var_ranges = 0;
+
+unsigned int *usage_table;
+static DECLARE_MUTEX(main_lock);
+
+u32 size_or_mask, size_and_mask;
+
+static struct mtrr_ops * mtrr_ops[X86_VENDOR_NUM] = {};
+
+struct mtrr_ops * mtrr_if = NULL;
+
+static void set_mtrr(unsigned int reg, unsigned long base,
+ unsigned long size, mtrr_type type);
+
+extern int arr3_protected;
+
+void set_mtrr_ops(struct mtrr_ops * ops)
+{
+ if (ops->vendor && ops->vendor < X86_VENDOR_NUM)
+ mtrr_ops[ops->vendor] = ops;
+}
+
+/* Returns non-zero if we have the write-combining memory type */
+static int have_wrcomb(void)
+{
+ struct pci_dev *dev;
+
+ if ((dev = pci_get_class(PCI_CLASS_BRIDGE_HOST << 8, NULL)) != NULL) {
+ /* ServerWorks LE chipsets have problems with write-combining
+ Don't allow it and leave room for other chipsets to be tagged */
+ if (dev->vendor == PCI_VENDOR_ID_SERVERWORKS &&
+ dev->device == PCI_DEVICE_ID_SERVERWORKS_LE) {
+ printk(KERN_INFO "mtrr: Serverworks LE detected. Write-combining disabled.\n");
+ pci_dev_put(dev);
+ return 0;
+ }
+ /* Intel 450NX errata # 23. Non ascending cachline evictions to
+ write combining memory may resulting in data corruption */
+ if (dev->vendor == PCI_VENDOR_ID_INTEL &&
+ dev->device == PCI_DEVICE_ID_INTEL_82451NX) {
+ printk(KERN_INFO "mtrr: Intel 450NX MMC detected. Write-combining disabled.\n");
+ pci_dev_put(dev);
+ return 0;
+ }
+ pci_dev_put(dev);
+ }
+ return (mtrr_if->have_wrcomb ? mtrr_if->have_wrcomb() : 0);
+}
+
+/* This function returns the number of variable MTRRs */
+static void __init set_num_var_ranges(void)
+{
+ unsigned long config = 0, dummy;
+
+ if (use_intel()) {
+ rdmsr(MTRRcap_MSR, config, dummy);
+ } else if (is_cpu(AMD))
+ config = 2;
+ else if (is_cpu(CYRIX) || is_cpu(CENTAUR))
+ config = 8;
+ num_var_ranges = config & 0xff;
+}
+
+static void __init init_table(void)
+{
+ int i, max;
+
+ max = num_var_ranges;
+ if ((usage_table = kmalloc(max * sizeof *usage_table, GFP_KERNEL))
+ == NULL) {
+ printk(KERN_ERR "mtrr: could not allocate\n");
+ return;
+ }
+ for (i = 0; i < max; i++)
+ usage_table[i] = 1;
+}
+
+struct set_mtrr_data {
+ atomic_t count;
+ atomic_t gate;
+ unsigned long smp_base;
+ unsigned long smp_size;
+ unsigned int smp_reg;
+ mtrr_type smp_type;
+};
+
+#ifdef CONFIG_SMP
+
+static void ipi_handler(void *info)
+/* [SUMMARY] Synchronisation handler. Executed by "other" CPUs.
+ [RETURNS] Nothing.
+*/
+{
+ struct set_mtrr_data *data = info;
+ unsigned long flags;
+
+ local_irq_save(flags);
+
+ atomic_dec(&data->count);
+ while(!atomic_read(&data->gate))
+ cpu_relax();
+
+ /* The master has cleared me to execute */
+ if (data->smp_reg != ~0U)
+ mtrr_if->set(data->smp_reg, data->smp_base,
+ data->smp_size, data->smp_type);
+ else
+ mtrr_if->set_all();
+
+ atomic_dec(&data->count);
+ while(atomic_read(&data->gate))
+ cpu_relax();
+
+ atomic_dec(&data->count);
+ local_irq_restore(flags);
+}
+
+#endif
+
+/**
+ * set_mtrr - update mtrrs on all processors
+ * @reg: mtrr in question
+ * @base: mtrr base
+ * @size: mtrr size
+ * @type: mtrr type
+ *
+ * This is kinda tricky, but fortunately, Intel spelled it out for us cleanly:
+ *
+ * 1. Send IPI to do the following:
+ * 2. Disable Interrupts
+ * 3. Wait for all procs to do so
+ * 4. Enter no-fill cache mode
+ * 5. Flush caches
+ * 6. Clear PGE bit
+ * 7. Flush all TLBs
+ * 8. Disable all range registers
+ * 9. Update the MTRRs
+ * 10. Enable all range registers
+ * 11. Flush all TLBs and caches again
+ * 12. Enter normal cache mode and reenable caching
+ * 13. Set PGE
+ * 14. Wait for buddies to catch up
+ * 15. Enable interrupts.
+ *
+ * What does that mean for us? Well, first we set data.count to the number
+ * of CPUs. As each CPU disables interrupts, it'll decrement it once. We wait
+ * until it hits 0 and proceed. We set the data.gate flag and reset data.count.
+ * Meanwhile, they are waiting for that flag to be set. Once it's set, each
+ * CPU goes through the transition of updating MTRRs. The CPU vendors may each do it
+ * differently, so we call mtrr_if->set() callback and let them take care of it.
+ * When they're done, they again decrement data->count and wait for data.gate to
+ * be reset.
+ * When we finish, we wait for data.count to hit 0 and toggle the data.gate flag.
+ * Everyone then enables interrupts and we all continue on.
+ *
+ * Note that the mechanism is the same for UP systems, too; all the SMP stuff
+ * becomes nops.
+ */
+static void set_mtrr(unsigned int reg, unsigned long base,
+ unsigned long size, mtrr_type type)
+{
+ struct set_mtrr_data data;
+ unsigned long flags;
+
+ data.smp_reg = reg;
+ data.smp_base = base;
+ data.smp_size = size;
+ data.smp_type = type;
+ atomic_set(&data.count, num_booting_cpus() - 1);
+ atomic_set(&data.gate,0);
+
+ /* Start the ball rolling on other CPUs */
+ if (smp_call_function(ipi_handler, &data, 1, 0) != 0)
+ panic("mtrr: timed out waiting for other CPUs\n");
+
+ local_irq_save(flags);
+
+ while(atomic_read(&data.count))
+ cpu_relax();
+
+ /* ok, reset count and toggle gate */
+ atomic_set(&data.count, num_booting_cpus() - 1);
+ atomic_set(&data.gate,1);
+
+ /* do our MTRR business */
+
+ /* HACK!
+ * We use this same function to initialize the mtrrs on boot.
+ * The state of the boot cpu's mtrrs has been saved, and we want
+ * to replicate across all the APs.
+ * If we're doing that @reg is set to something special...
+ */
+ if (reg != ~0U)
+ mtrr_if->set(reg,base,size,type);
+
+ /* wait for the others */
+ while(atomic_read(&data.count))
+ cpu_relax();
+
+ atomic_set(&data.count, num_booting_cpus() - 1);
+ atomic_set(&data.gate,0);
+
+ /*
+ * Wait here for everyone to have seen the gate change
+ * So we're the last ones to touch 'data'
+ */
+ while(atomic_read(&data.count))
+ cpu_relax();
+
+ local_irq_restore(flags);
+}
+
+/**
+ * mtrr_add_page - Add a memory type region
+ * @base: Physical base address of region in pages (4 KB)
+ * @size: Physical size of region in pages (4 KB)
+ * @type: Type of MTRR desired
+ * @increment: If this is true do usage counting on the region
+ *
+ * Memory type region registers control the caching on newer Intel and
+ * non Intel processors. This function allows drivers to request an
+ * MTRR is added. The details and hardware specifics of each processor's
+ * implementation are hidden from the caller, but nevertheless the
+ * caller should expect to need to provide a power of two size on an
+ * equivalent power of two boundary.
+ *
+ * If the region cannot be added either because all regions are in use
+ * or the CPU cannot support it a negative value is returned. On success
+ * the register number for this entry is returned, but should be treated
+ * as a cookie only.
+ *
+ * On a multiprocessor machine the changes are made to all processors.
+ * This is required on x86 by the Intel processors.
+ *
+ * The available types are
+ *
+ * %MTRR_TYPE_UNCACHABLE - No caching
+ *
+ * %MTRR_TYPE_WRBACK - Write data back in bursts whenever
+ *
+ * %MTRR_TYPE_WRCOMB - Write data back soon but allow bursts
+ *
+ * %MTRR_TYPE_WRTHROUGH - Cache reads but not writes
+ *
+ * BUGS: Needs a quiet flag for the cases where drivers do not mind
+ * failures and do not wish system log messages to be sent.
+ */
+
+int mtrr_add_page(unsigned long base, unsigned long size,
+ unsigned int type, char increment)
+{
+ int i;
+ mtrr_type ltype;
+ unsigned long lbase;
+ unsigned int lsize;
+ int error;
+
+ if (!mtrr_if)
+ return -ENXIO;
+
+ if ((error = mtrr_if->validate_add_page(base,size,type)))
+ return error;
+
+ if (type >= MTRR_NUM_TYPES) {
+ printk(KERN_WARNING "mtrr: type: %u invalid\n", type);
+ return -EINVAL;
+ }
+
+ /* If the type is WC, check that this processor supports it */
+ if ((type == MTRR_TYPE_WRCOMB) && !have_wrcomb()) {
+ printk(KERN_WARNING
+ "mtrr: your processor doesn't support write-combining\n");
+ return -ENOSYS;
+ }
+
+ if (base & size_or_mask || size & size_or_mask) {
+ printk(KERN_WARNING "mtrr: base or size exceeds the MTRR width\n");
+ return -EINVAL;
+ }
+
+ error = -EINVAL;
+
+ /* Search for existing MTRR */
+ down(&main_lock);
+ for (i = 0; i < num_var_ranges; ++i) {
+ mtrr_if->get(i, &lbase, &lsize, &ltype);
+ if (base >= lbase + lsize)
+ continue;
+ if ((base < lbase) && (base + size <= lbase))
+ continue;
+ /* At this point we know there is some kind of overlap/enclosure */
+ if ((base < lbase) || (base + size > lbase + lsize)) {
+ printk(KERN_WARNING
+ "mtrr: 0x%lx000,0x%lx000 overlaps existing"
+ " 0x%lx000,0x%x000\n", base, size, lbase,
+ lsize);
+ goto out;
+ }
+ /* New region is enclosed by an existing region */
+ if (ltype != type) {
+ if (type == MTRR_TYPE_UNCACHABLE)
+ continue;
+ printk (KERN_WARNING "mtrr: type mismatch for %lx000,%lx000 old: %s new: %s\n",
+ base, size, mtrr_attrib_to_str(ltype),
+ mtrr_attrib_to_str(type));
+ goto out;
+ }
+ if (increment)
+ ++usage_table[i];
+ error = i;
+ goto out;
+ }
+ /* Search for an empty MTRR */
+ i = mtrr_if->get_free_region(base, size);
+ if (i >= 0) {
+ set_mtrr(i, base, size, type);
+ usage_table[i] = 1;
+ } else
+ printk(KERN_INFO "mtrr: no more MTRRs available\n");
+ error = i;
+ out:
+ up(&main_lock);
+ return error;
+}
+
+/**
+ * mtrr_add - Add a memory type region
+ * @base: Physical base address of region
+ * @size: Physical size of region
+ * @type: Type of MTRR desired
+ * @increment: If this is true do usage counting on the region
+ *
+ * Memory type region registers control the caching on newer Intel and
+ * non Intel processors. This function allows drivers to request an
+ * MTRR is added. The details and hardware specifics of each processor's
+ * implementation are hidden from the caller, but nevertheless the
+ * caller should expect to need to provide a power of two size on an
+ * equivalent power of two boundary.
+ *
+ * If the region cannot be added either because all regions are in use
+ * or the CPU cannot support it a negative value is returned. On success
+ * the register number for this entry is returned, but should be treated
+ * as a cookie only.
+ *
+ * On a multiprocessor machine the changes are made to all processors.
+ * This is required on x86 by the Intel processors.
+ *
+ * The available types are
+ *
+ * %MTRR_TYPE_UNCACHABLE - No caching
+ *
+ * %MTRR_TYPE_WRBACK - Write data back in bursts whenever
+ *
+ * %MTRR_TYPE_WRCOMB - Write data back soon but allow bursts
+ *
+ * %MTRR_TYPE_WRTHROUGH - Cache reads but not writes
+ *
+ * BUGS: Needs a quiet flag for the cases where drivers do not mind
+ * failures and do not wish system log messages to be sent.
+ */
+
+int
+mtrr_add(unsigned long base, unsigned long size, unsigned int type,
+ char increment)
+{
+ if ((base & (PAGE_SIZE - 1)) || (size & (PAGE_SIZE - 1))) {
+ printk(KERN_WARNING "mtrr: size and base must be multiples of 4 kiB\n");
+ printk(KERN_DEBUG "mtrr: size: 0x%lx base: 0x%lx\n", size, base);
+ return -EINVAL;
+ }
+ return mtrr_add_page(base >> PAGE_SHIFT, size >> PAGE_SHIFT, type,
+ increment);
+}
+
+/**
+ * mtrr_del_page - delete a memory type region
+ * @reg: Register returned by mtrr_add
+ * @base: Physical base address
+ * @size: Size of region
+ *
+ * If register is supplied then base and size are ignored. This is
+ * how drivers should call it.
+ *
+ * Releases an MTRR region. If the usage count drops to zero the
+ * register is freed and the region returns to default state.
+ * On success the register is returned, on failure a negative error
+ * code.
+ */
+
+int mtrr_del_page(int reg, unsigned long base, unsigned long size)
+{
+ int i, max;
+ mtrr_type ltype;
+ unsigned long lbase;
+ unsigned int lsize;
+ int error = -EINVAL;
+
+ if (!mtrr_if)
+ return -ENXIO;
+
+ max = num_var_ranges;
+ down(&main_lock);
+ if (reg < 0) {
+ /* Search for existing MTRR */
+ for (i = 0; i < max; ++i) {
+ mtrr_if->get(i, &lbase, &lsize, &ltype);
+ if (lbase == base && lsize == size) {
+ reg = i;
+ break;
+ }
+ }
+ if (reg < 0) {
+ printk(KERN_DEBUG "mtrr: no MTRR for %lx000,%lx000 found\n", base,
+ size);
+ goto out;
+ }
+ }
+ if (reg >= max) {
+ printk(KERN_WARNING "mtrr: register: %d too big\n", reg);
+ goto out;
+ }
+ if (is_cpu(CYRIX) && !use_intel()) {
+ if ((reg == 3) && arr3_protected) {
+ printk(KERN_WARNING "mtrr: ARR3 cannot be changed\n");
+ goto out;
+ }
+ }
+ mtrr_if->get(reg, &lbase, &lsize, &ltype);
+ if (lsize < 1) {
+ printk(KERN_WARNING "mtrr: MTRR %d not used\n", reg);
+ goto out;
+ }
+ if (usage_table[reg] < 1) {
+ printk(KERN_WARNING "mtrr: reg: %d has count=0\n", reg);
+ goto out;
+ }
+ if (--usage_table[reg] < 1)
+ set_mtrr(reg, 0, 0, 0);
+ error = reg;
+ out:
+ up(&main_lock);
+ return error;
+}
+/**
+ * mtrr_del - delete a memory type region
+ * @reg: Register returned by mtrr_add
+ * @base: Physical base address
+ * @size: Size of region
+ *
+ * If register is supplied then base and size are ignored. This is
+ * how drivers should call it.
+ *
+ * Releases an MTRR region. If the usage count drops to zero the
+ * register is freed and the region returns to default state.
+ * On success the register is returned, on failure a negative error
+ * code.
+ */
+
+int
+mtrr_del(int reg, unsigned long base, unsigned long size)
+{
+ if ((base & (PAGE_SIZE - 1)) || (size & (PAGE_SIZE - 1))) {
+ printk(KERN_INFO "mtrr: size and base must be multiples of 4 kiB\n");
+ printk(KERN_DEBUG "mtrr: size: 0x%lx base: 0x%lx\n", size, base);
+ return -EINVAL;
+ }
+ return mtrr_del_page(reg, base >> PAGE_SHIFT, size >> PAGE_SHIFT);
+}
+
+EXPORT_SYMBOL(mtrr_add);
+EXPORT_SYMBOL(mtrr_del);
+
+/* HACK ALERT!
+ * These should be called implicitly, but we can't yet until all the initcall
+ * stuff is done...
+ */
+extern void amd_init_mtrr(void);
+extern void cyrix_init_mtrr(void);
+extern void centaur_init_mtrr(void);
+
+static void __init init_ifs(void)
+{
+ amd_init_mtrr();
+ cyrix_init_mtrr();
+ centaur_init_mtrr();
+}
+
+static void __init init_other_cpus(void)
+{
+ if (use_intel())
+ get_mtrr_state();
+
+ /* bring up the other processors */
+ set_mtrr(~0U,0,0,0);
+
+ if (use_intel()) {
+ finalize_mtrr_state();
+ mtrr_state_warn();
+ }
+}
+
+
+struct mtrr_value {
+ mtrr_type ltype;
+ unsigned long lbase;
+ unsigned int lsize;
+};
+
+static struct mtrr_value * mtrr_state;
+
+static int mtrr_save(struct sys_device * sysdev, u32 state)
+{
+ int i;
+ int size = num_var_ranges * sizeof(struct mtrr_value);
+
+ mtrr_state = kmalloc(size,GFP_ATOMIC);
+ if (mtrr_state)
+ memset(mtrr_state,0,size);
+ else
+ return -ENOMEM;
+
+ for (i = 0; i < num_var_ranges; i++) {
+ mtrr_if->get(i,
+ &mtrr_state[i].lbase,
+ &mtrr_state[i].lsize,
+ &mtrr_state[i].ltype);
+ }
+ return 0;
+}
+
+static int mtrr_restore(struct sys_device * sysdev)
+{
+ int i;
+
+ for (i = 0; i < num_var_ranges; i++) {
+ if (mtrr_state[i].lsize)
+ set_mtrr(i,
+ mtrr_state[i].lbase,
+ mtrr_state[i].lsize,
+ mtrr_state[i].ltype);
+ }
+ kfree(mtrr_state);
+ return 0;
+}
+
+
+
+static struct sysdev_driver mtrr_sysdev_driver = {
+ .suspend = mtrr_save,
+ .resume = mtrr_restore,
+};
+
+
+/**
+ * mtrr_init - initialize mtrrs on the boot CPU
+ *
+ * This needs to be called early; before any of the other CPUs are
+ * initialized (i.e. before smp_init()).
+ *
+ */
+static int __init mtrr_init(void)
+{
+ init_ifs();
+
+ if (cpu_has_mtrr) {
+ mtrr_if = &generic_mtrr_ops;
+ size_or_mask = 0xff000000; /* 36 bits */
+ size_and_mask = 0x00f00000;
+
+ switch (boot_cpu_data.x86_vendor) {
+ case X86_VENDOR_AMD:
+ /* The original Athlon docs said that
+ total addressable memory is 44 bits wide.
+ It was not really clear whether its MTRRs
+ follow this or not. (Read: 44 or 36 bits).
+ However, "x86-64_overview.pdf" explicitly
+ states that "previous implementations support
+ 36 bit MTRRs" and also provides a way to
+ query the width (in bits) of the physical
+ addressable memory on the Hammer family.
+ */
+ if (boot_cpu_data.x86 == 15
+ && (cpuid_eax(0x80000000) >= 0x80000008)) {
+ u32 phys_addr;
+ phys_addr = cpuid_eax(0x80000008) & 0xff;
+ size_or_mask =
+ ~((1 << (phys_addr - PAGE_SHIFT)) - 1);
+ size_and_mask = ~size_or_mask & 0xfff00000;
+ }
+ /* Athlon MTRRs use an Intel-compatible interface for
+ * getting and setting */
+ break;
+ case X86_VENDOR_CENTAUR:
+ if (boot_cpu_data.x86 == 6) {
+ /* VIA Cyrix family have Intel style MTRRs, but don't support PAE */
+ size_or_mask = 0xfff00000; /* 32 bits */
+ size_and_mask = 0;
+ }
+ break;
+
+ default:
+ break;
+ }
+ } else {
+ switch (boot_cpu_data.x86_vendor) {
+ case X86_VENDOR_AMD:
+ if (cpu_has_k6_mtrr) {
+ /* Pre-Athlon (K6) AMD CPU MTRRs */
+ mtrr_if = mtrr_ops[X86_VENDOR_AMD];
+ size_or_mask = 0xfff00000; /* 32 bits */
+ size_and_mask = 0;
+ }
+ break;
+ case X86_VENDOR_CENTAUR:
+ if (cpu_has_centaur_mcr) {
+ mtrr_if = mtrr_ops[X86_VENDOR_CENTAUR];
+ size_or_mask = 0xfff00000; /* 32 bits */
+ size_and_mask = 0;
+ }
+ break;
+ case X86_VENDOR_CYRIX:
+ if (cpu_has_cyrix_arr) {
+ mtrr_if = mtrr_ops[X86_VENDOR_CYRIX];
+ size_or_mask = 0xfff00000; /* 32 bits */
+ size_and_mask = 0;
+ }
+ break;
+ default:
+ break;
+ }
+ }
+ printk(KERN_INFO "mtrr: v%s\n",MTRR_VERSION);
+
+ if (mtrr_if) {
+ set_num_var_ranges();
+ init_table();
+ init_other_cpus();
+
+ return sysdev_driver_register(&cpu_sysdev_class,
+ &mtrr_sysdev_driver);
+ }
+ return -ENXIO;
+}
+
+subsys_initcall(mtrr_init);