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 {
  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  */
  87 struct vma_data {
  88         atomic_t refcnt;        /* Number of vmas sharing the data. */
  89         spinlock_t lock;        /* Serialize access to the vma. */
  90         int count;              /* Number of pages allocated. */
  91         int type;               /* Type of pages allocated. */
  92         unsigned long maddr[0]; /* Array of MSPEC addresses. */
  93 };
  94
  95 /* used on shub2 to clear FOP cache in the HUB */
  96 static unsigned long scratch_page[MAX_NUMNODES];
  97 #define SH2_AMO_CACHE_ENTRIES   4
  98
  99 static inline int
 100 mspec_zero_block(unsigned long addr, int len)
 101 {
 102         int status;
 103
 104         if (is_sn2) {
 105                 if (is_shub2()) {
 106                         int nid;
 107                         void *p;
 108                         int i;
 109
 110                         nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
 111                         p = (void *)TO_AMO(scratch_page[nid]);
 112
 113                         for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
 114                                 FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
 115                                 p += FETCHOP_VAR_SIZE;
 116                         }
 117                 }
 118
 119                 status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
 120                                   BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
 121         } else {
 122                 memset((char *) addr, 0, len);
 123                 status = 0;
 124         }
 125         return status;
 126 }
 127
 128 /*
 129  * mspec_open
 130  *
 131  * Called when a device mapping is created by a means other than mmap
 132  * (via fork, etc.).  Increments the reference count on the underlying
 133  * mspec data so it is not freed prematurely.
 134  */
 135 static void
 136 mspec_open(struct vm_area_struct *vma)
 137 {
 138         struct vma_data *vdata;
 139
 140         vdata = vma->vm_private_data;
 141         atomic_inc(&vdata->refcnt);
 142 }
 143
 144 /*
 145  * mspec_close
 146  *
 147  * Called when unmapping a device mapping. Frees all mspec pages
 148  * belonging to the vma.
 149  */
 150 static void
 151 mspec_close(struct vm_area_struct *vma)
 152 {
 153         struct vma_data *vdata;
 154         int i, pages, result, vdata_size;
 155
 156         vdata = vma->vm_private_data;
 157         if (!atomic_dec_and_test(&vdata->refcnt))
 158                 return;
 159
 160         pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 161         vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
 162         for (i = 0; i < pages; i++) {
 163                 if (vdata->maddr[i] == 0)
 164                         continue;
 165                 /*
 166                  * Clear the page before sticking it back
 167                  * into the pool.
 168                  */
 169                 result = mspec_zero_block(vdata->maddr[i], PAGE_SIZE);
 170                 if (!result)
 171                         uncached_free_page(vdata->maddr[i]);
 172                 else
 173                         printk(KERN_WARNING "mspec_close(): "
 174                                "failed to zero page %i\n",
 175                                result);
 176         }
 177
 178         if (vdata_size <= PAGE_SIZE)
 179                 kfree(vdata);
 180         else
 181                 vfree(vdata);
 182 }
 183
 184
 185 /*
 186  * mspec_nopfn
 187  *
 188  * Creates a mspec page and maps it to user space.
 189  */
 190 static unsigned long
 191 mspec_nopfn(struct vm_area_struct *vma, unsigned long address)
 192 {
 193         unsigned long paddr, maddr;
 194         unsigned long pfn;
 195         int index;
 196         struct vma_data *vdata = vma->vm_private_data;
 197
 198         index = (address - vma->vm_start) >> PAGE_SHIFT;
 199         maddr = (volatile unsigned long) vdata->maddr[index];
 200         if (maddr == 0) {
 201                 maddr = uncached_alloc_page(numa_node_id());
 202                 if (maddr == 0)
 203                         return NOPFN_OOM;
 204
 205                 spin_lock(&vdata->lock);
 206                 if (vdata->maddr[index] == 0) {
 207                         vdata->count++;
 208                         vdata->maddr[index] = maddr;
 209                 } else {
 210                         uncached_free_page(maddr);
 211                         maddr = vdata->maddr[index];
 212                 }
 213                 spin_unlock(&vdata->lock);
 214         }
 215
 216         if (vdata->type == MSPEC_FETCHOP)
 217                 paddr = TO_AMO(maddr);
 218         else
 219                 paddr = maddr & ~__IA64_UNCACHED_OFFSET;
 220
 221         pfn = paddr >> PAGE_SHIFT;
 222
 223         return pfn;
 224 }
 225
 226 static struct vm_operations_struct mspec_vm_ops = {
 227         .open = mspec_open,
 228         .close = mspec_close,
 229         .nopfn = mspec_nopfn
 230 };
 231
 232 /*
 233  * mspec_mmap
 234  *
 235  * Called when mmaping the device.  Initializes the vma with a fault handler
 236  * and private data structure necessary to allocate, track, and free the
 237  * underlying pages.
 238  */
 239 static int
 240 mspec_mmap(struct file *file, struct vm_area_struct *vma, int type)
 241 {
 242         struct vma_data *vdata;
 243         int pages, vdata_size;
 244
 245         if (vma->vm_pgoff != 0)
 246                 return -EINVAL;
 247
 248         if ((vma->vm_flags & VM_SHARED) == 0)
 249                 return -EINVAL;
 250
 251         if ((vma->vm_flags & VM_WRITE) == 0)
 252                 return -EPERM;
 253
 254         pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 255         vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
 256         if (vdata_size <= PAGE_SIZE)
 257                 vdata = kmalloc(vdata_size, GFP_KERNEL);
 258         else
 259                 vdata = vmalloc(vdata_size);
 260         if (!vdata)
 261                 return -ENOMEM;
 262         memset(vdata, 0, vdata_size);
 263
 264         vdata->type = type;
 265         spin_lock_init(&vdata->lock);
 266         vdata->refcnt = ATOMIC_INIT(1);
 267         vma->vm_private_data = vdata;
 268
 269         vma->vm_flags |= (VM_IO | VM_RESERVED | VM_PFNMAP);
 270         if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
 271                 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 272         vma->vm_ops = &mspec_vm_ops;
 273
 274         return 0;
 275 }
 276
 277 static int
 278 fetchop_mmap(struct file *file, struct vm_area_struct *vma)
 279 {
 280         return mspec_mmap(file, vma, MSPEC_FETCHOP);
 281 }
 282
 283 static int
 284 cached_mmap(struct file *file, struct vm_area_struct *vma)
 285 {
 286         return mspec_mmap(file, vma, MSPEC_CACHED);
 287 }
 288
 289 static int
 290 uncached_mmap(struct file *file, struct vm_area_struct *vma)
 291 {
 292         return mspec_mmap(file, vma, MSPEC_UNCACHED);
 293 }
 294
 295 static const struct file_operations fetchop_fops = {
 296         .owner = THIS_MODULE,
 297         .mmap = fetchop_mmap
 298 };
 299
 300 static struct miscdevice fetchop_miscdev = {
 301         .minor = MISC_DYNAMIC_MINOR,
 302         .name = "sgi_fetchop",
 303         .fops = &fetchop_fops
 304 };
 305
 306 static const struct file_operations cached_fops = {
 307         .owner = THIS_MODULE,
 308         .mmap = cached_mmap
 309 };
 310
 311 static struct miscdevice cached_miscdev = {
 312         .minor = MISC_DYNAMIC_MINOR,
 313         .name = "mspec_cached",
 314         .fops = &cached_fops
 315 };
 316
 317 static const struct file_operations uncached_fops = {
 318         .owner = THIS_MODULE,
 319         .mmap = uncached_mmap
 320 };
 321
 322 static struct miscdevice uncached_miscdev = {
 323         .minor = MISC_DYNAMIC_MINOR,
 324         .name = "mspec_uncached",
 325         .fops = &uncached_fops
 326 };
 327
 328 /*
 329  * mspec_init
 330  *
 331  * Called at boot time to initialize the mspec facility.
 332  */
 333 static int __init
 334 mspec_init(void)
 335 {
 336         int ret;
 337         int nid;
 338
 339         /*
 340          * The fetchop device only works on SN2 hardware, uncached and cached
 341          * memory drivers should both be valid on all ia64 hardware
 342          */
 343 #ifdef CONFIG_SGI_SN
 344         if (ia64_platform_is("sn2")) {
 345                 is_sn2 = 1;
 346                 if (is_shub2()) {
 347                         ret = -ENOMEM;
 348                         for_each_online_node(nid) {
 349                                 int actual_nid;
 350                                 int nasid;
 351                                 unsigned long phys;
 352
 353                                 scratch_page[nid] = uncached_alloc_page(nid);
 354                                 if (scratch_page[nid] == 0)
 355                                         goto free_scratch_pages;
 356                                 phys = __pa(scratch_page[nid]);
 357                                 nasid = get_node_number(phys);
 358                                 actual_nid = nasid_to_cnodeid(nasid);
 359                                 if (actual_nid != nid)
 360                                         goto free_scratch_pages;
 361                         }
 362                 }
 363
 364                 ret = misc_register(&fetchop_miscdev);
 365                 if (ret) {
 366                         printk(KERN_ERR
 367                                "%s: failed to register device %i\n",
 368                                FETCHOP_ID, ret);
 369                         goto free_scratch_pages;
 370                 }
 371         }
 372 #endif
 373         ret = misc_register(&cached_miscdev);
 374         if (ret) {
 375                 printk(KERN_ERR "%s: failed to register device %i\n",
 376                        CACHED_ID, ret);
 377                 if (is_sn2)
 378                         misc_deregister(&fetchop_miscdev);
 379                 goto free_scratch_pages;
 380         }
 381         ret = misc_register(&uncached_miscdev);
 382         if (ret) {
 383                 printk(KERN_ERR "%s: failed to register device %i\n",
 384                        UNCACHED_ID, ret);
 385                 misc_deregister(&cached_miscdev);
 386                 if (is_sn2)
 387                         misc_deregister(&fetchop_miscdev);
 388                 goto free_scratch_pages;
 389         }
 390
 391         printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
 392                MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
 393                CACHED_ID, UNCACHED_ID);
 394
 395         return 0;
 396
 397  free_scratch_pages:
 398         for_each_node(nid) {
 399                 if (scratch_page[nid] != 0)
 400                         uncached_free_page(scratch_page[nid]);
 401         }
 402         return ret;
 403 }
 404
 405 static void __exit
 406 mspec_exit(void)
 407 {
 408         int nid;
 409
 410         misc_deregister(&uncached_miscdev);
 411         misc_deregister(&cached_miscdev);
 412         if (is_sn2) {
 413                 misc_deregister(&fetchop_miscdev);
 414
 415                 for_each_node(nid) {
 416                         if (scratch_page[nid] != 0)
 417                                 uncached_free_page(scratch_page[nid]);
 418                 }
 419         }
 420 }
 421
 422 module_init(mspec_init);
 423 module_exit(mspec_exit);
 424
 425 MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
 426 MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
 427 MODULE_LICENSE("GPL");