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 <linux/refcount.h>
  47 #include <asm/page.h>
  48 #include <asm/pgtable.h>
  49 #include <linux/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         refcount_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         unsigned long vm_start; /* Original (unsplit) base. */
  98         unsigned long vm_end;   /* Original (unsplit) end. */
  99         unsigned long maddr[0]; /* Array of MSPEC addresses. */
 100 };
 101
 102 /* used on shub2 to clear FOP cache in the HUB */
 103 static unsigned long scratch_page[MAX_NUMNODES];
 104 #define SH2_AMO_CACHE_ENTRIES   4
 105
 106 static inline int
 107 mspec_zero_block(unsigned long addr, int len)
 108 {
 109         int status;
 110
 111         if (is_sn2) {
 112                 if (is_shub2()) {
 113                         int nid;
 114                         void *p;
 115                         int i;
 116
 117                         nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
 118                         p = (void *)TO_AMO(scratch_page[nid]);
 119
 120                         for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
 121                                 FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
 122                                 p += FETCHOP_VAR_SIZE;
 123                         }
 124                 }
 125
 126                 status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
 127                                   BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
 128         } else {
 129                 memset((char *) addr, 0, len);
 130                 status = 0;
 131         }
 132         return status;
 133 }
 134
 135 /*
 136  * mspec_open
 137  *
 138  * Called when a device mapping is created by a means other than mmap
 139  * (via fork, munmap, etc.).  Increments the reference count on the
 140  * underlying mspec data so it is not freed prematurely.
 141  */
 142 static void
 143 mspec_open(struct vm_area_struct *vma)
 144 {
 145         struct vma_data *vdata;
 146
 147         vdata = vma->vm_private_data;
 148         refcount_inc(&vdata->refcnt);
 149 }
 150
 151 /*
 152  * mspec_close
 153  *
 154  * Called when unmapping a device mapping. Frees all mspec pages
 155  * belonging to all the vma's sharing this vma_data structure.
 156  */
 157 static void
 158 mspec_close(struct vm_area_struct *vma)
 159 {
 160         struct vma_data *vdata;
 161         int index, last_index;
 162         unsigned long my_page;
 163
 164         vdata = vma->vm_private_data;
 165
 166         if (!refcount_dec_and_test(&vdata->refcnt))
 167                 return;
 168
 169         last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
 170         for (index = 0; index < last_index; index++) {
 171                 if (vdata->maddr[index] == 0)
 172                         continue;
 173                 /*
 174                  * Clear the page before sticking it back
 175                  * into the pool.
 176                  */
 177                 my_page = vdata->maddr[index];
 178                 vdata->maddr[index] = 0;
 179                 if (!mspec_zero_block(my_page, PAGE_SIZE))
 180                         uncached_free_page(my_page, 1);
 181                 else
 182                         printk(KERN_WARNING "mspec_close(): "
 183                                "failed to zero page %ld\n", my_page);
 184         }
 185
 186         kvfree(vdata);
 187 }
 188
 189 /*
 190  * mspec_fault
 191  *
 192  * Creates a mspec page and maps it to user space.
 193  */
 194 static int
 195 mspec_fault(struct vm_fault *vmf)
 196 {
 197         unsigned long paddr, maddr;
 198         unsigned long pfn;
 199         pgoff_t index = vmf->pgoff;
 200         struct vma_data *vdata = vmf->vma->vm_private_data;
 201
 202         maddr = (volatile unsigned long) vdata->maddr[index];
 203         if (maddr == 0) {
 204                 maddr = uncached_alloc_page(numa_node_id(), 1);
 205                 if (maddr == 0)
 206                         return VM_FAULT_OOM;
 207
 208                 spin_lock(&vdata->lock);
 209                 if (vdata->maddr[index] == 0) {
 210                         vdata->count++;
 211                         vdata->maddr[index] = maddr;
 212                 } else {
 213                         uncached_free_page(maddr, 1);
 214                         maddr = vdata->maddr[index];
 215                 }
 216                 spin_unlock(&vdata->lock);
 217         }
 218
 219         if (vdata->type == MSPEC_FETCHOP)
 220                 paddr = TO_AMO(maddr);
 221         else
 222                 paddr = maddr & ~__IA64_UNCACHED_OFFSET;
 223
 224         pfn = paddr >> PAGE_SHIFT;
 225
 226         /*
 227          * vm_insert_pfn can fail with -EBUSY, but in that case it will
 228          * be because another thread has installed the pte first, so it
 229          * is no problem.
 230          */
 231         vm_insert_pfn(vmf->vma, vmf->address, pfn);
 232
 233         return VM_FAULT_NOPAGE;
 234 }
 235
 236 static const struct vm_operations_struct mspec_vm_ops = {
 237         .open = mspec_open,
 238         .close = mspec_close,
 239         .fault = mspec_fault,
 240 };
 241
 242 /*
 243  * mspec_mmap
 244  *
 245  * Called when mmapping the device.  Initializes the vma with a fault handler
 246  * and private data structure necessary to allocate, track, and free the
 247  * underlying pages.
 248  */
 249 static int
 250 mspec_mmap(struct file *file, struct vm_area_struct *vma,
 251                                         enum mspec_page_type type)
 252 {
 253         struct vma_data *vdata;
 254         int pages, vdata_size;
 255
 256         if (vma->vm_pgoff != 0)
 257                 return -EINVAL;
 258
 259         if ((vma->vm_flags & VM_SHARED) == 0)
 260                 return -EINVAL;
 261
 262         if ((vma->vm_flags & VM_WRITE) == 0)
 263                 return -EPERM;
 264
 265         pages = vma_pages(vma);
 266         vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
 267         if (vdata_size <= PAGE_SIZE)
 268                 vdata = kzalloc(vdata_size, GFP_KERNEL);
 269         else
 270                 vdata = vzalloc(vdata_size);
 271         if (!vdata)
 272                 return -ENOMEM;
 273
 274         vdata->vm_start = vma->vm_start;
 275         vdata->vm_end = vma->vm_end;
 276         vdata->type = type;
 277         spin_lock_init(&vdata->lock);
 278         refcount_set(&vdata->refcnt, 1);
 279         vma->vm_private_data = vdata;
 280
 281         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
 282         if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
 283                 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 284         vma->vm_ops = &mspec_vm_ops;
 285
 286         return 0;
 287 }
 288
 289 static int
 290 fetchop_mmap(struct file *file, struct vm_area_struct *vma)
 291 {
 292         return mspec_mmap(file, vma, MSPEC_FETCHOP);
 293 }
 294
 295 static int
 296 cached_mmap(struct file *file, struct vm_area_struct *vma)
 297 {
 298         return mspec_mmap(file, vma, MSPEC_CACHED);
 299 }
 300
 301 static int
 302 uncached_mmap(struct file *file, struct vm_area_struct *vma)
 303 {
 304         return mspec_mmap(file, vma, MSPEC_UNCACHED);
 305 }
 306
 307 static const struct file_operations fetchop_fops = {
 308         .owner = THIS_MODULE,
 309         .mmap = fetchop_mmap,
 310         .llseek = noop_llseek,
 311 };
 312
 313 static struct miscdevice fetchop_miscdev = {
 314         .minor = MISC_DYNAMIC_MINOR,
 315         .name = "sgi_fetchop",
 316         .fops = &fetchop_fops
 317 };
 318
 319 static const struct file_operations cached_fops = {
 320         .owner = THIS_MODULE,
 321         .mmap = cached_mmap,
 322         .llseek = noop_llseek,
 323 };
 324
 325 static struct miscdevice cached_miscdev = {
 326         .minor = MISC_DYNAMIC_MINOR,
 327         .name = "mspec_cached",
 328         .fops = &cached_fops
 329 };
 330
 331 static const struct file_operations uncached_fops = {
 332         .owner = THIS_MODULE,
 333         .mmap = uncached_mmap,
 334         .llseek = noop_llseek,
 335 };
 336
 337 static struct miscdevice uncached_miscdev = {
 338         .minor = MISC_DYNAMIC_MINOR,
 339         .name = "mspec_uncached",
 340         .fops = &uncached_fops
 341 };
 342
 343 /*
 344  * mspec_init
 345  *
 346  * Called at boot time to initialize the mspec facility.
 347  */
 348 static int __init
 349 mspec_init(void)
 350 {
 351         int ret;
 352         int nid;
 353
 354         /*
 355          * The fetchop device only works on SN2 hardware, uncached and cached
 356          * memory drivers should both be valid on all ia64 hardware
 357          */
 358 #ifdef CONFIG_SGI_SN
 359         if (ia64_platform_is("sn2")) {
 360                 is_sn2 = 1;
 361                 if (is_shub2()) {
 362                         ret = -ENOMEM;
 363                         for_each_node_state(nid, N_ONLINE) {
 364                                 int actual_nid;
 365                                 int nasid;
 366                                 unsigned long phys;
 367
 368                                 scratch_page[nid] = uncached_alloc_page(nid, 1);
 369                                 if (scratch_page[nid] == 0)
 370                                         goto free_scratch_pages;
 371                                 phys = __pa(scratch_page[nid]);
 372                                 nasid = get_node_number(phys);
 373                                 actual_nid = nasid_to_cnodeid(nasid);
 374                                 if (actual_nid != nid)
 375                                         goto free_scratch_pages;
 376                         }
 377                 }
 378
 379                 ret = misc_register(&fetchop_miscdev);
 380                 if (ret) {
 381                         printk(KERN_ERR
 382                                "%s: failed to register device %i\n",
 383                                FETCHOP_ID, ret);
 384                         goto free_scratch_pages;
 385                 }
 386         }
 387 #endif
 388         ret = misc_register(&cached_miscdev);
 389         if (ret) {
 390                 printk(KERN_ERR "%s: failed to register device %i\n",
 391                        CACHED_ID, ret);
 392                 if (is_sn2)
 393                         misc_deregister(&fetchop_miscdev);
 394                 goto free_scratch_pages;
 395         }
 396         ret = misc_register(&uncached_miscdev);
 397         if (ret) {
 398                 printk(KERN_ERR "%s: failed to register device %i\n",
 399                        UNCACHED_ID, ret);
 400                 misc_deregister(&cached_miscdev);
 401                 if (is_sn2)
 402                         misc_deregister(&fetchop_miscdev);
 403                 goto free_scratch_pages;
 404         }
 405
 406         printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
 407                MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
 408                CACHED_ID, UNCACHED_ID);
 409
 410         return 0;
 411
 412  free_scratch_pages:
 413         for_each_node(nid) {
 414                 if (scratch_page[nid] != 0)
 415                         uncached_free_page(scratch_page[nid], 1);
 416         }
 417         return ret;
 418 }
 419
 420 static void __exit
 421 mspec_exit(void)
 422 {
 423         int nid;
 424
 425         misc_deregister(&uncached_miscdev);
 426         misc_deregister(&cached_miscdev);
 427         if (is_sn2) {
 428                 misc_deregister(&fetchop_miscdev);
 429
 430                 for_each_node(nid) {
 431                         if (scratch_page[nid] != 0)
 432                                 uncached_free_page(scratch_page[nid], 1);
 433                 }
 434         }
 435 }
 436
 437 module_init(mspec_init);
 438 module_exit(mspec_exit);
 439
 440 MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
 441 MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
 442 MODULE_LICENSE("GPL");