drivers/char/mspec.c

   1 /*
   2  * Copyright (C) 2001-2006 Silicon Graphics, Inc.  All rights
   3  * reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of version 2 of the GNU General Public License
   7  * as published by the Free Software Foundation.
   8  */
   9
  10 /*
  11  * SN Platform Special Memory (mspec) Support
  12  *
  13  * This driver exports the SN special memory (mspec) facility to user
  14  * processes.
  15  * There are three types of memory made available thru this driver:
  16  * fetchops, uncached and cached.
  17  *
  18  * Fetchops are atomic memory operations that are implemented in the
  19  * memory controller on SGI SN hardware.
  20  *
  21  * Uncached are used for memory write combining feature of the ia64
  22  * cpu.
  23  *
  24  * Cached are used for areas of memory that are used as cached addresses
  25  * on our partition and used as uncached addresses from other partitions.
  26  * Due to a design constraint of the SN2 Shub, you can not have processors
  27  * on the same FSB perform both a cached and uncached reference to the
  28  * same cache line.  These special memory cached regions prevent the
  29  * kernel from ever dropping in a TLB entry and therefore prevent the
  30  * processor from ever speculating a cache line from this page.
  31  */
  32
  33 #include <linux/types.h>
  34 #include <linux/kernel.h>
  35 #include <linux/module.h>
  36 #include <linux/init.h>
  37 #include <linux/errno.h>
  38 #include <linux/miscdevice.h>
  39 #include <linux/spinlock.h>
  40 #include <linux/mm.h>
  41 #include <linux/fs.h>
  42 #include <linux/vmalloc.h>
  43 #include <linux/string.h>
  44 #include <linux/slab.h>
  45 #include <linux/numa.h>
  46 #include <asm/page.h>
  47 #include <asm/system.h>
  48 #include <asm/pgtable.h>
  49 #include <asm/atomic.h>
  50 #include <asm/tlbflush.h>
  51 #include <asm/uncached.h>
  52 #include <asm/sn/addrs.h>
  53 #include <asm/sn/arch.h>
  54 #include <asm/sn/mspec.h>
  55 #include <asm/sn/sn_cpuid.h>
  56 #include <asm/sn/io.h>
  57 #include <asm/sn/bte.h>
  58 #include <asm/sn/shubio.h>
  59
  60
  61 #define FETCHOP_ID      "SGI Fetchop,"
  62 #define CACHED_ID       "Cached,"
  63 #define UNCACHED_ID     "Uncached"
  64 #define REVISION        "4.0"
  65 #define MSPEC_BASENAME  "mspec"
  66
  67 /*
  68  * Page types allocated by the device.
  69  */
  70 enum mspec_page_type {
  71         MSPEC_FETCHOP = 1,
  72         MSPEC_CACHED,
  73         MSPEC_UNCACHED
  74 };
  75
  76 #ifdef CONFIG_SGI_SN
  77 static int is_sn2;
  78 #else
  79 #define is_sn2          0
  80 #endif
  81
  82 /*
  83  * One of these structures is allocated when an mspec region is mmaped. The
  84  * structure is pointed to by the vma->vm_private_data field in the vma struct.
  85  * This structure is used to record the addresses of the mspec pages.
  86  * This structure is shared by all vma's that are split off from the
  87  * original vma when split_vma()'s are done.
  88  *
  89  * The refcnt is incremented atomically because mm->mmap_sem does not
  90  * protect in fork case where multiple tasks share the vma_data.
  91  */
  92 struct vma_data {
  93         atomic_t refcnt;        /* Number of vmas sharing the data. */
  94         spinlock_t lock;        /* Serialize access to this structure. */
  95         int count;              /* Number of pages allocated. */
  96         enum mspec_page_type type; /* Type of pages allocated. */
  97         int flags;              /* See VMD_xxx below. */
  98         unsigned long vm_start; /* Original (unsplit) base. */
  99         unsigned long vm_end;   /* Original (unsplit) end. */
 100         unsigned long maddr[0]; /* Array of MSPEC addresses. */
 101 };
 102
 103 #define VMD_VMALLOCED 0x1       /* vmalloc'd rather than kmalloc'd */
 104
 105 /* used on shub2 to clear FOP cache in the HUB */
 106 static unsigned long scratch_page[MAX_NUMNODES];
 107 #define SH2_AMO_CACHE_ENTRIES   4
 108
 109 static inline int
 110 mspec_zero_block(unsigned long addr, int len)
 111 {
 112         int status;
 113
 114         if (is_sn2) {
 115                 if (is_shub2()) {
 116                         int nid;
 117                         void *p;
 118                         int i;
 119
 120                         nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
 121                         p = (void *)TO_AMO(scratch_page[nid]);
 122
 123                         for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
 124                                 FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
 125                                 p += FETCHOP_VAR_SIZE;
 126                         }
 127                 }
 128
 129                 status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
 130                                   BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
 131         } else {
 132                 memset((char *) addr, 0, len);
 133                 status = 0;
 134         }
 135         return status;
 136 }
 137
 138 /*
 139  * mspec_open
 140  *
 141  * Called when a device mapping is created by a means other than mmap
 142  * (via fork, munmap, etc.).  Increments the reference count on the
 143  * underlying mspec data so it is not freed prematurely.
 144  */
 145 static void
 146 mspec_open(struct vm_area_struct *vma)
 147 {
 148         struct vma_data *vdata;
 149
 150         vdata = vma->vm_private_data;
 151         atomic_inc(&vdata->refcnt);
 152 }
 153
 154 /*
 155  * mspec_close
 156  *
 157  * Called when unmapping a device mapping. Frees all mspec pages
 158  * belonging to all the vma's sharing this vma_data structure.
 159  */
 160 static void
 161 mspec_close(struct vm_area_struct *vma)
 162 {
 163         struct vma_data *vdata;
 164         int index, last_index;
 165         unsigned long my_page;
 166
 167         vdata = vma->vm_private_data;
 168
 169         if (!atomic_dec_and_test(&vdata->refcnt))
 170                 return;
 171
 172         last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
 173         for (index = 0; index < last_index; index++) {
 174                 if (vdata->maddr[index] == 0)
 175                         continue;
 176                 /*
 177                  * Clear the page before sticking it back
 178                  * into the pool.
 179                  */
 180                 my_page = vdata->maddr[index];
 181                 vdata->maddr[index] = 0;
 182                 if (!mspec_zero_block(my_page, PAGE_SIZE))
 183                         uncached_free_page(my_page, 1);
 184                 else
 185                         printk(KERN_WARNING "mspec_close(): "
 186                                "failed to zero page %ld\n", my_page);
 187         }
 188
 189         if (vdata->flags & VMD_VMALLOCED)
 190                 vfree(vdata);
 191         else
 192                 kfree(vdata);
 193 }
 194
 195 /*
 196  * mspec_fault
 197  *
 198  * Creates a mspec page and maps it to user space.
 199  */
 200 static int
 201 mspec_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 202 {
 203         unsigned long paddr, maddr;
 204         unsigned long pfn;
 205         pgoff_t index = vmf->pgoff;
 206         struct vma_data *vdata = vma->vm_private_data;
 207
 208         maddr = (volatile unsigned long) vdata->maddr[index];
 209         if (maddr == 0) {
 210                 maddr = uncached_alloc_page(numa_node_id(), 1);
 211                 if (maddr == 0)
 212                         return VM_FAULT_OOM;
 213
 214                 spin_lock(&vdata->lock);
 215                 if (vdata->maddr[index] == 0) {
 216                         vdata->count++;
 217                         vdata->maddr[index] = maddr;
 218                 } else {
 219                         uncached_free_page(maddr, 1);
 220                         maddr = vdata->maddr[index];
 221                 }
 222                 spin_unlock(&vdata->lock);
 223         }
 224
 225         if (vdata->type == MSPEC_FETCHOP)
 226                 paddr = TO_AMO(maddr);
 227         else
 228                 paddr = maddr & ~__IA64_UNCACHED_OFFSET;
 229
 230         pfn = paddr >> PAGE_SHIFT;
 231
 232         /*
 233          * vm_insert_pfn can fail with -EBUSY, but in that case it will
 234          * be because another thread has installed the pte first, so it
 235          * is no problem.
 236          */
 237         vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);
 238
 239         return VM_FAULT_NOPAGE;
 240 }
 241
 242 static const struct vm_operations_struct mspec_vm_ops = {
 243         .open = mspec_open,
 244         .close = mspec_close,
 245         .fault = mspec_fault,
 246 };
 247
 248 /*
 249  * mspec_mmap
 250  *
 251  * Called when mmapping the device.  Initializes the vma with a fault handler
 252  * and private data structure necessary to allocate, track, and free the
 253  * underlying pages.
 254  */
 255 static int
 256 mspec_mmap(struct file *file, struct vm_area_struct *vma,
 257                                         enum mspec_page_type type)
 258 {
 259         struct vma_data *vdata;
 260         int pages, vdata_size, flags = 0;
 261
 262         if (vma->vm_pgoff != 0)
 263                 return -EINVAL;
 264
 265         if ((vma->vm_flags & VM_SHARED) == 0)
 266                 return -EINVAL;
 267
 268         if ((vma->vm_flags & VM_WRITE) == 0)
 269                 return -EPERM;
 270
 271         pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 272         vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
 273         if (vdata_size <= PAGE_SIZE)
 274                 vdata = kmalloc(vdata_size, GFP_KERNEL);
 275         else {
 276                 vdata = vmalloc(vdata_size);
 277                 flags = VMD_VMALLOCED;
 278         }
 279         if (!vdata)
 280                 return -ENOMEM;
 281         memset(vdata, 0, vdata_size);
 282
 283         vdata->vm_start = vma->vm_start;
 284         vdata->vm_end = vma->vm_end;
 285         vdata->flags = flags;
 286         vdata->type = type;
 287         spin_lock_init(&vdata->lock);
 288         vdata->refcnt = ATOMIC_INIT(1);
 289         vma->vm_private_data = vdata;
 290
 291         vma->vm_flags |= (VM_IO | VM_RESERVED | VM_PFNMAP | VM_DONTEXPAND);
 292         if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
 293                 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 294         vma->vm_ops = &mspec_vm_ops;
 295
 296         return 0;
 297 }
 298
 299 static int
 300 fetchop_mmap(struct file *file, struct vm_area_struct *vma)
 301 {
 302         return mspec_mmap(file, vma, MSPEC_FETCHOP);
 303 }
 304
 305 static int
 306 cached_mmap(struct file *file, struct vm_area_struct *vma)
 307 {
 308         return mspec_mmap(file, vma, MSPEC_CACHED);
 309 }
 310
 311 static int
 312 uncached_mmap(struct file *file, struct vm_area_struct *vma)
 313 {
 314         return mspec_mmap(file, vma, MSPEC_UNCACHED);
 315 }
 316
 317 static const struct file_operations fetchop_fops = {
 318         .owner = THIS_MODULE,
 319         .mmap = fetchop_mmap
 320 };
 321
 322 static struct miscdevice fetchop_miscdev = {
 323         .minor = MISC_DYNAMIC_MINOR,
 324         .name = "sgi_fetchop",
 325         .fops = &fetchop_fops
 326 };
 327
 328 static const struct file_operations cached_fops = {
 329         .owner = THIS_MODULE,
 330         .mmap = cached_mmap
 331 };
 332
 333 static struct miscdevice cached_miscdev = {
 334         .minor = MISC_DYNAMIC_MINOR,
 335         .name = "mspec_cached",
 336         .fops = &cached_fops
 337 };
 338
 339 static const struct file_operations uncached_fops = {
 340         .owner = THIS_MODULE,
 341         .mmap = uncached_mmap
 342 };
 343
 344 static struct miscdevice uncached_miscdev = {
 345         .minor = MISC_DYNAMIC_MINOR,
 346         .name = "mspec_uncached",
 347         .fops = &uncached_fops
 348 };
 349
 350 /*
 351  * mspec_init
 352  *
 353  * Called at boot time to initialize the mspec facility.
 354  */
 355 static int __init
 356 mspec_init(void)
 357 {
 358         int ret;
 359         int nid;
 360
 361         /*
 362          * The fetchop device only works on SN2 hardware, uncached and cached
 363          * memory drivers should both be valid on all ia64 hardware
 364          */
 365 #ifdef CONFIG_SGI_SN
 366         if (ia64_platform_is("sn2")) {
 367                 is_sn2 = 1;
 368                 if (is_shub2()) {
 369                         ret = -ENOMEM;
 370                         for_each_node_state(nid, N_ONLINE) {
 371                                 int actual_nid;
 372                                 int nasid;
 373                                 unsigned long phys;
 374
 375                                 scratch_page[nid] = uncached_alloc_page(nid, 1);
 376                                 if (scratch_page[nid] == 0)
 377                                         goto free_scratch_pages;
 378                                 phys = __pa(scratch_page[nid]);
 379                                 nasid = get_node_number(phys);
 380                                 actual_nid = nasid_to_cnodeid(nasid);
 381                                 if (actual_nid != nid)
 382                                         goto free_scratch_pages;
 383                         }
 384                 }
 385
 386                 ret = misc_register(&fetchop_miscdev);
 387                 if (ret) {
 388                         printk(KERN_ERR
 389                                "%s: failed to register device %i\n",
 390                                FETCHOP_ID, ret);
 391                         goto free_scratch_pages;
 392                 }
 393         }
 394 #endif
 395         ret = misc_register(&cached_miscdev);
 396         if (ret) {
 397                 printk(KERN_ERR "%s: failed to register device %i\n",
 398                        CACHED_ID, ret);
 399                 if (is_sn2)
 400                         misc_deregister(&fetchop_miscdev);
 401                 goto free_scratch_pages;
 402         }
 403         ret = misc_register(&uncached_miscdev);
 404         if (ret) {
 405                 printk(KERN_ERR "%s: failed to register device %i\n",
 406                        UNCACHED_ID, ret);
 407                 misc_deregister(&cached_miscdev);
 408                 if (is_sn2)
 409                         misc_deregister(&fetchop_miscdev);
 410                 goto free_scratch_pages;
 411         }
 412
 413         printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
 414                MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
 415                CACHED_ID, UNCACHED_ID);
 416
 417         return 0;
 418
 419  free_scratch_pages:
 420         for_each_node(nid) {
 421                 if (scratch_page[nid] != 0)
 422                         uncached_free_page(scratch_page[nid], 1);
 423         }
 424         return ret;
 425 }
 426
 427 static void __exit
 428 mspec_exit(void)
 429 {
 430         int nid;
 431
 432         misc_deregister(&uncached_miscdev);
 433         misc_deregister(&cached_miscdev);
 434         if (is_sn2) {
 435                 misc_deregister(&fetchop_miscdev);
 436
 437                 for_each_node(nid) {
 438                         if (scratch_page[nid] != 0)
 439                                 uncached_free_page(scratch_page[nid], 1);
 440                 }
 441         }
 442 }
 443
 444 module_init(mspec_init);
 445 module_exit(mspec_exit);
 446
 447 MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
 448 MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
 449 MODULE_LICENSE("GPL");