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/*

 * Copyright (C) 2001-2006 Silicon Graphics, Inc.  All rights

 * reserved.

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of version 2 of the GNU General Public License

 * as published by the Free Software Foundation.

 */

/*

 * SN Platform Special Memory (mspec) Support

 *

 * This driver exports the SN special memory (mspec) facility to user

 * processes.

 * There are three types of memory made available thru this driver:

 * fetchops, uncached and cached.

 *

 * Fetchops are atomic memory operations that are implemented in the

 * memory controller on SGI SN hardware.

 *

 * Uncached are used for memory write combining feature of the ia64

 * cpu.

 *

 * Cached are used for areas of memory that are used as cached addresses

 * on our partition and used as uncached addresses from other partitions.

 * Due to a design constraint of the SN2 Shub, you can not have processors

 * on the same FSB perform both a cached and uncached reference to the

 * same cache line.  These special memory cached regions prevent the

 * kernel from ever dropping in a TLB entry and therefore prevent the

 * processor from ever speculating a cache line from this page.

 */

#include <linux/types.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/errno.h>

#include <linux/miscdevice.h>

#include <linux/spinlock.h>

#include <linux/mm.h>

#include <linux/fs.h>

#include <linux/vmalloc.h>

#include <linux/string.h>

#include <linux/slab.h>

#include <linux/numa.h>

#include <asm/page.h>

#include <asm/system.h>

#include <asm/pgtable.h>

#include <asm/atomic.h>

#include <asm/tlbflush.h>

#include <asm/uncached.h>

#include <asm/sn/addrs.h>

#include <asm/sn/arch.h>

#include <asm/sn/mspec.h>

#include <asm/sn/sn_cpuid.h>

#include <asm/sn/io.h>

#include <asm/sn/bte.h>

#include <asm/sn/shubio.h>

#define FETCHOP_ID      "SGI Fetchop,"

#define CACHED_ID       "Cached,"

#define UNCACHED_ID     "Uncached"

#define REVISION        "4.0"

#define MSPEC_BASENAME  "mspec"

/*

 * Page types allocated by the device.

 */

enum mspec_page_type {

        MSPEC_FETCHOP = 1,

        MSPEC_CACHED,

        MSPEC_UNCACHED

};

#ifdef CONFIG_SGI_SN

static int is_sn2;

#else

#define is_sn2          0

#endif

/*

 * One of these structures is allocated when an mspec region is mmaped. The

 * structure is pointed to by the vma->vm_private_data field in the vma struct.

 * This structure is used to record the addresses of the mspec pages.

 * This structure is shared by all vma's that are split off from the

 * original vma when split_vma()'s are done.

 *

 * The refcnt is incremented atomically because mm->mmap_sem does not

 * protect in fork case where multiple tasks share the vma_data.

 */

struct vma_data {

        atomic_t refcnt;        /* Number of vmas sharing the data. */

        spinlock_t lock;        /* Serialize access to this structure. */

        int count;              /* Number of pages allocated. */

        enum mspec_page_type type; /* Type of pages allocated. */

        int flags;              /* See VMD_xxx below. */

        unsigned long vm_start; /* Original (unsplit) base. */

        unsigned long vm_end;   /* Original (unsplit) end. */

        unsigned long maddr[0];  /* Array of MSPEC addresses. */

};

#define VMD_VMALLOCED 0x1       /* vmalloc'd rather than kmalloc'd */

/* used on shub2 to clear FOP cache in the HUB */

static unsigned long scratch_page[MAX_NUMNODES];

#define SH2_AMO_CACHE_ENTRIES   4

static inline int

mspec_zero_block(unsigned long addr, int len)

{

        int status;

        if (is_sn2) {

                if (is_shub2()) {

                        int nid;

                        void *p;

                        int i;

                        nid = nasid_to_cnodeid(get_node_number(__pa(addr)));

                        p = (void *)TO_AMO(scratch_page[nid]);

                        for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {

                                FETCHOP_LOAD_OP(p, FETCHOP_LOAD);

                                p += FETCHOP_VAR_SIZE;

                        }

                }

                status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,

                                  BTE_WACQUIRE | BTE_ZERO_FILL, NULL);

        } else {

                memset((char *) addr, 0, len);

                status = 0;

        }

        return status;

}

/*

 * mspec_open

 *

 * Called when a device mapping is created by a means other than mmap

 * (via fork, munmap, etc.).  Increments the reference count on the

 * underlying mspec data so it is not freed prematurely.

 */

static void

mspec_open(struct vm_area_struct *vma)

{

        struct vma_data *vdata;

        vdata = vma->vm_private_data;

        atomic_inc(&vdata->refcnt);

}

/*

 * mspec_close

 *

 * Called when unmapping a device mapping. Frees all mspec pages

 * belonging to all the vma's sharing this vma_data structure.

 */

static void

mspec_close(struct vm_area_struct *vma)

{

        struct vma_data *vdata;

        int index, last_index;

        unsigned long my_page;

        vdata = vma->vm_private_data;

        if (!atomic_dec_and_test(&vdata->refcnt))

                return;

        last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;

        for (index = 0; index < last_index; index++) {

                if (vdata->maddr[index] == 0)

                        continue;

                /*

                 * Clear the page before sticking it back

                 * into the pool.

                 */

                my_page = vdata->maddr[index];

                vdata->maddr[index] = 0;

                if (!mspec_zero_block(my_page, PAGE_SIZE))

                        uncached_free_page(my_page);

                else

                        printk(KERN_WARNING "mspec_close(): "

                               "failed to zero page %ld\n", my_page);

        }

        if (vdata->flags & VMD_VMALLOCED)

                vfree(vdata);

        else

                kfree(vdata);

}

/*

 * mspec_nopfn

 *

 * Creates a mspec page and maps it to user space.

 */

static unsigned long

mspec_nopfn(struct vm_area_struct *vma, unsigned long address)

{

        unsigned long paddr, maddr;

        unsigned long pfn;

        int index;

        struct vma_data *vdata = vma->vm_private_data;

        BUG_ON(address < vdata->vm_start || address >= vdata->vm_end);

        index = (address - vdata->vm_start) >> PAGE_SHIFT;

        maddr = (volatile unsigned long) vdata->maddr[index];

        if (maddr == 0) {

                maddr = uncached_alloc_page(numa_node_id());

                if (maddr == 0)

                        return NOPFN_OOM;

                spin_lock(&vdata->lock);

                if (vdata->maddr[index] == 0) {

                        vdata->count++;

                        vdata->maddr[index] = maddr;

                } else {

                        uncached_free_page(maddr);

                        maddr = vdata->maddr[index];

                }

                spin_unlock(&vdata->lock);

        }

        if (vdata->type == MSPEC_FETCHOP)

                paddr = TO_AMO(maddr);

        else

                paddr = maddr & ~__IA64_UNCACHED_OFFSET;

        pfn = paddr >> PAGE_SHIFT;

        return pfn;

}

static struct vm_operations_struct mspec_vm_ops = {

        .open = mspec_open,

        .close = mspec_close,

        .nopfn = mspec_nopfn

};

/*

 * mspec_mmap

 *

 * Called when mmaping the device.  Initializes the vma with a fault handler

 * and private data structure necessary to allocate, track, and free the

 * underlying pages.

 */

static int

mspec_mmap(struct file *file, struct vm_area_struct *vma,

                                        enum mspec_page_type type)

{

        struct vma_data *vdata;

        int pages, vdata_size, flags = 0;

        if (vma->vm_pgoff != 0)

                return -EINVAL;

        if ((vma->vm_flags & VM_SHARED) == 0)

                return -EINVAL;

        if ((vma->vm_flags & VM_WRITE) == 0)

                return -EPERM;

        pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;

        vdata_size = sizeof(struct vma_data) + pages * sizeof(long);

        if (vdata_size <= PAGE_SIZE)

                vdata = kmalloc(vdata_size, GFP_KERNEL);

        else {

                vdata = vmalloc(vdata_size);

                flags = VMD_VMALLOCED;

        }

        if (!vdata)

                return -ENOMEM;

        memset(vdata, 0, vdata_size);

        vdata->vm_start = vma->vm_start;

        vdata->vm_end = vma->vm_end;

        vdata->flags = flags;

        vdata->type = type;

        spin_lock_init(&vdata->lock);

        vdata->refcnt = ATOMIC_INIT(1);

        vma->vm_private_data = vdata;

        vma->vm_flags |= (VM_IO | VM_RESERVED | VM_PFNMAP);

        if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)

                vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

        vma->vm_ops = &mspec_vm_ops;

        return 0;

}

static int

fetchop_mmap(struct file *file, struct vm_area_struct *vma)

{

        return mspec_mmap(file, vma, MSPEC_FETCHOP);

}

static int

cached_mmap(struct file *file, struct vm_area_struct *vma)

{

        return mspec_mmap(file, vma, MSPEC_CACHED);

}

static int

uncached_mmap(struct file *file, struct vm_area_struct *vma)

{

        return mspec_mmap(file, vma, MSPEC_UNCACHED);

}

static const struct file_operations fetchop_fops = {

        .owner = THIS_MODULE,

        .mmap = fetchop_mmap

};

static struct miscdevice fetchop_miscdev = {

        .minor = MISC_DYNAMIC_MINOR,

        .name = "sgi_fetchop",

        .fops = &fetchop_fops

};

static const struct file_operations cached_fops = {

        .owner = THIS_MODULE,

        .mmap = cached_mmap

};

static struct miscdevice cached_miscdev = {

        .minor = MISC_DYNAMIC_MINOR,

        .name = "mspec_cached",

        .fops = &cached_fops

};

static const struct file_operations uncached_fops = {

        .owner = THIS_MODULE,

        .mmap = uncached_mmap

};

static struct miscdevice uncached_miscdev = {

        .minor = MISC_DYNAMIC_MINOR,

        .name = "mspec_uncached",

        .fops = &uncached_fops

};

/*

 * mspec_init

 *

 * Called at boot time to initialize the mspec facility.

 */

static int __init

mspec_init(void)

{

        int ret;

        int nid;

        /*

         * The fetchop device only works on SN2 hardware, uncached and cached

         * memory drivers should both be valid on all ia64 hardware

         */

#ifdef CONFIG_SGI_SN

        if (ia64_platform_is("sn2")) {

                is_sn2 = 1;

                if (is_shub2()) {

                        ret = -ENOMEM;

                        for_each_node_state(nid, N_ONLINE) {

                                int actual_nid;

                                int nasid;

                                unsigned long phys;

                                scratch_page[nid] = uncached_alloc_page(nid);

                                if (scratch_page[nid] == 0)

                                        goto free_scratch_pages;

                                phys = __pa(scratch_page[nid]);

                                nasid = get_node_number(phys);

                                actual_nid = nasid_to_cnodeid(nasid);

                                if (actual_nid != nid)

                                        goto free_scratch_pages;

                        }

                }

                ret = misc_register(&fetchop_miscdev);

                if (ret) {

                        printk(KERN_ERR

                               "%s: failed to register device %i\n",

                               FETCHOP_ID, ret);

                        goto free_scratch_pages;

                }

        }

#endif

        ret = misc_register(&cached_miscdev);

        if (ret) {

                printk(KERN_ERR "%s: failed to register device %i\n",

                       CACHED_ID, ret);

                if (is_sn2)

                        misc_deregister(&fetchop_miscdev);

                goto free_scratch_pages;

        }

        ret = misc_register(&uncached_miscdev);

        if (ret) {

                printk(KERN_ERR "%s: failed to register device %i\n",

                       UNCACHED_ID, ret);

                misc_deregister(&cached_miscdev);

                if (is_sn2)

                        misc_deregister(&fetchop_miscdev);

                goto free_scratch_pages;

        }

        printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",

               MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",

               CACHED_ID, UNCACHED_ID);

        return 0;

 free_scratch_pages:

        for_each_node(nid) {

                if (scratch_page[nid] != 0)

                        uncached_free_page(scratch_page[nid]);

        }

        return ret;

}

static void __exit

mspec_exit(void)

{

        int nid;

        misc_deregister(&uncached_miscdev);

        misc_deregister(&cached_miscdev);

        if (is_sn2) {

                misc_deregister(&fetchop_miscdev);

                for_each_node(nid) {

                        if (scratch_page[nid] != 0)

                                uncached_free_page(scratch_page[nid]);

                }

        }

}

module_init(mspec_init);

module_exit(mspec_exit);

MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");

MODULE_DESCRIPTION("Driver for SGI SN special memory operations");

MODULE_LICENSE("GPL");