296 lines
7.1 KiB
C
296 lines
7.1 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2001-2006 Silicon Graphics, Inc. All rights
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* reserved.
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*/
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/*
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* SN Platform Special Memory (mspec) Support
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*
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* This driver exports the SN special memory (mspec) facility to user
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* processes.
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* There are two types of memory made available thru this driver:
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* uncached and cached.
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*
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* Uncached are used for memory write combining feature of the ia64
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* cpu.
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*
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* Cached are used for areas of memory that are used as cached addresses
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* on our partition and used as uncached addresses from other partitions.
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* Due to a design constraint of the SN2 Shub, you can not have processors
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* on the same FSB perform both a cached and uncached reference to the
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* same cache line. These special memory cached regions prevent the
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* kernel from ever dropping in a TLB entry and therefore prevent the
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* processor from ever speculating a cache line from this page.
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*/
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/errno.h>
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#include <linux/miscdevice.h>
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#include <linux/spinlock.h>
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/vmalloc.h>
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#include <linux/string.h>
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#include <linux/slab.h>
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#include <linux/numa.h>
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#include <linux/refcount.h>
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#include <asm/page.h>
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#include <linux/atomic.h>
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#include <asm/tlbflush.h>
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#include <asm/uncached.h>
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#define CACHED_ID "Cached,"
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#define UNCACHED_ID "Uncached"
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#define REVISION "4.0"
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#define MSPEC_BASENAME "mspec"
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/*
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* Page types allocated by the device.
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*/
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enum mspec_page_type {
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MSPEC_CACHED = 2,
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MSPEC_UNCACHED
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};
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/*
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* One of these structures is allocated when an mspec region is mmaped. The
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* structure is pointed to by the vma->vm_private_data field in the vma struct.
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* This structure is used to record the addresses of the mspec pages.
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* This structure is shared by all vma's that are split off from the
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* original vma when split_vma()'s are done.
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*
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* The refcnt is incremented atomically because mm->mmap_lock does not
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* protect in fork case where multiple tasks share the vma_data.
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*/
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struct vma_data {
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refcount_t refcnt; /* Number of vmas sharing the data. */
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spinlock_t lock; /* Serialize access to this structure. */
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int count; /* Number of pages allocated. */
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enum mspec_page_type type; /* Type of pages allocated. */
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unsigned long vm_start; /* Original (unsplit) base. */
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unsigned long vm_end; /* Original (unsplit) end. */
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unsigned long maddr[]; /* Array of MSPEC addresses. */
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};
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/*
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* mspec_open
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*
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* Called when a device mapping is created by a means other than mmap
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* (via fork, munmap, etc.). Increments the reference count on the
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* underlying mspec data so it is not freed prematurely.
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*/
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static void
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mspec_open(struct vm_area_struct *vma)
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{
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struct vma_data *vdata;
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vdata = vma->vm_private_data;
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refcount_inc(&vdata->refcnt);
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}
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/*
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* mspec_close
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*
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* Called when unmapping a device mapping. Frees all mspec pages
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* belonging to all the vma's sharing this vma_data structure.
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*/
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static void
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mspec_close(struct vm_area_struct *vma)
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{
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struct vma_data *vdata;
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int index, last_index;
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unsigned long my_page;
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vdata = vma->vm_private_data;
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if (!refcount_dec_and_test(&vdata->refcnt))
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return;
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last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
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for (index = 0; index < last_index; index++) {
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if (vdata->maddr[index] == 0)
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continue;
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/*
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* Clear the page before sticking it back
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* into the pool.
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*/
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my_page = vdata->maddr[index];
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vdata->maddr[index] = 0;
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memset((char *)my_page, 0, PAGE_SIZE);
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uncached_free_page(my_page, 1);
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}
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kvfree(vdata);
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}
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/*
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* mspec_fault
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*
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* Creates a mspec page and maps it to user space.
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*/
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static vm_fault_t
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mspec_fault(struct vm_fault *vmf)
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{
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unsigned long paddr, maddr;
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unsigned long pfn;
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pgoff_t index = vmf->pgoff;
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struct vma_data *vdata = vmf->vma->vm_private_data;
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maddr = (volatile unsigned long) vdata->maddr[index];
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if (maddr == 0) {
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maddr = uncached_alloc_page(numa_node_id(), 1);
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if (maddr == 0)
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return VM_FAULT_OOM;
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spin_lock(&vdata->lock);
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if (vdata->maddr[index] == 0) {
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vdata->count++;
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vdata->maddr[index] = maddr;
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} else {
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uncached_free_page(maddr, 1);
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maddr = vdata->maddr[index];
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}
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spin_unlock(&vdata->lock);
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}
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paddr = maddr & ~__IA64_UNCACHED_OFFSET;
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pfn = paddr >> PAGE_SHIFT;
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return vmf_insert_pfn(vmf->vma, vmf->address, pfn);
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}
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static const struct vm_operations_struct mspec_vm_ops = {
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.open = mspec_open,
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.close = mspec_close,
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.fault = mspec_fault,
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};
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/*
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* mspec_mmap
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*
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* Called when mmapping the device. Initializes the vma with a fault handler
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* and private data structure necessary to allocate, track, and free the
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* underlying pages.
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*/
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static int
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mspec_mmap(struct file *file, struct vm_area_struct *vma,
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enum mspec_page_type type)
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{
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struct vma_data *vdata;
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int pages, vdata_size;
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if (vma->vm_pgoff != 0)
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return -EINVAL;
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if ((vma->vm_flags & VM_SHARED) == 0)
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return -EINVAL;
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if ((vma->vm_flags & VM_WRITE) == 0)
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return -EPERM;
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pages = vma_pages(vma);
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vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
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vdata = kvzalloc(vdata_size, GFP_KERNEL);
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if (!vdata)
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return -ENOMEM;
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vdata->vm_start = vma->vm_start;
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vdata->vm_end = vma->vm_end;
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vdata->type = type;
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spin_lock_init(&vdata->lock);
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refcount_set(&vdata->refcnt, 1);
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vma->vm_private_data = vdata;
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vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
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if (vdata->type == MSPEC_UNCACHED)
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vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
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vma->vm_ops = &mspec_vm_ops;
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return 0;
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}
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static int
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cached_mmap(struct file *file, struct vm_area_struct *vma)
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{
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return mspec_mmap(file, vma, MSPEC_CACHED);
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}
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static int
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uncached_mmap(struct file *file, struct vm_area_struct *vma)
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{
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return mspec_mmap(file, vma, MSPEC_UNCACHED);
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}
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static const struct file_operations cached_fops = {
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.owner = THIS_MODULE,
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.mmap = cached_mmap,
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.llseek = noop_llseek,
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};
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static struct miscdevice cached_miscdev = {
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.minor = MISC_DYNAMIC_MINOR,
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.name = "mspec_cached",
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.fops = &cached_fops
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};
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static const struct file_operations uncached_fops = {
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.owner = THIS_MODULE,
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.mmap = uncached_mmap,
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.llseek = noop_llseek,
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};
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static struct miscdevice uncached_miscdev = {
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.minor = MISC_DYNAMIC_MINOR,
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.name = "mspec_uncached",
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.fops = &uncached_fops
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};
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/*
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* mspec_init
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*
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* Called at boot time to initialize the mspec facility.
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*/
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static int __init
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mspec_init(void)
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{
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int ret;
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ret = misc_register(&cached_miscdev);
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if (ret) {
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printk(KERN_ERR "%s: failed to register device %i\n",
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CACHED_ID, ret);
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return ret;
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}
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ret = misc_register(&uncached_miscdev);
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if (ret) {
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printk(KERN_ERR "%s: failed to register device %i\n",
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UNCACHED_ID, ret);
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misc_deregister(&cached_miscdev);
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return ret;
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}
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printk(KERN_INFO "%s %s initialized devices: %s %s\n",
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MSPEC_BASENAME, REVISION, CACHED_ID, UNCACHED_ID);
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return 0;
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}
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static void __exit
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mspec_exit(void)
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{
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misc_deregister(&uncached_miscdev);
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misc_deregister(&cached_miscdev);
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}
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module_init(mspec_init);
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module_exit(mspec_exit);
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MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
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MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
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MODULE_LICENSE("GPL");
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