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/vmalloc.h>
  42 #include <linux/string.h>
  43 #include <linux/slab.h>
  44 #include <linux/numa.h>
  45 #include <asm/page.h>
  46 #include <asm/system.h>
  47 #include <asm/pgtable.h>
  48 #include <asm/atomic.h>
  49 #include <asm/tlbflush.h>
  50 #include <asm/uncached.h>
  51 #include <asm/sn/addrs.h>
  52 #include <asm/sn/arch.h>
  53 #include <asm/sn/mspec.h>
  54 #include <asm/sn/sn_cpuid.h>
  55 #include <asm/sn/io.h>
  56 #include <asm/sn/bte.h>
  57 #include <asm/sn/shubio.h>
  58
  59
  60 #define FETCHOP_ID      "SGI Fetchop,"
  61 #define CACHED_ID       "Cached,"
  62 #define UNCACHED_ID     "Uncached"
  63 #define REVISION        "4.0"
  64 #define MSPEC_BASENAME  "mspec"
  65
  66 /*
  67  * Page types allocated by the device.
  68  */
  69 enum {
  70         MSPEC_FETCHOP = 1,
  71         MSPEC_CACHED,
  72         MSPEC_UNCACHED
  73 };
  74
  75 static int is_sn2;
  76
  77 /*
  78  * One of these structures is allocated when an mspec region is mmaped. The
  79  * structure is pointed to by the vma->vm_private_data field in the vma struct.
  80  * This structure is used to record the addresses of the mspec pages.
  81  */
  82 struct vma_data {
  83         atomic_t refcnt;        /* Number of vmas sharing the data. */
  84         spinlock_t lock;        /* Serialize access to the vma. */
  85         int count;              /* Number of pages allocated. */
  86         int type;               /* Type of pages allocated. */
  87         unsigned long maddr[0]; /* Array of MSPEC addresses. */
  88 };
  89
  90 /* used on shub2 to clear FOP cache in the HUB */
  91 static unsigned long scratch_page[MAX_NUMNODES];
  92 #define SH2_AMO_CACHE_ENTRIES   4
  93
  94 static inline int
  95 mspec_zero_block(unsigned long addr, int len)
  96 {
  97         int status;
  98
  99         if (is_sn2) {
 100                 if (is_shub2()) {
 101                         int nid;
 102                         void *p;
 103                         int i;
 104
 105                         nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
 106                         p = (void *)TO_AMO(scratch_page[nid]);
 107
 108                         for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
 109                                 FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
 110                                 p += FETCHOP_VAR_SIZE;
 111                         }
 112                 }
 113
 114                 status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
 115                                   BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
 116         } else {
 117                 memset((char *) addr, 0, len);
 118                 status = 0;
 119         }
 120         return status;
 121 }
 122
 123 /*
 124  * mspec_open
 125  *
 126  * Called when a device mapping is created by a means other than mmap
 127  * (via fork, etc.).  Increments the reference count on the underlying
 128  * mspec data so it is not freed prematurely.
 129  */
 130 static void
 131 mspec_open(struct vm_area_struct *vma)
 132 {
 133         struct vma_data *vdata;
 134
 135         vdata = vma->vm_private_data;
 136         atomic_inc(&vdata->refcnt);
 137 }
 138
 139 /*
 140  * mspec_close
 141  *
 142  * Called when unmapping a device mapping. Frees all mspec pages
 143  * belonging to the vma.
 144  */
 145 static void
 146 mspec_close(struct vm_area_struct *vma)
 147 {
 148         struct vma_data *vdata;
 149         int i, pages, result, vdata_size;
 150
 151         vdata = vma->vm_private_data;
 152         if (!atomic_dec_and_test(&vdata->refcnt))
 153                 return;
 154
 155         pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 156         vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
 157         for (i = 0; i < pages; i++) {
 158                 if (vdata->maddr[i] == 0)
 159                         continue;
 160                 /*
 161                  * Clear the page before sticking it back
 162                  * into the pool.
 163                  */
 164                 result = mspec_zero_block(vdata->maddr[i], PAGE_SIZE);
 165                 if (!result)
 166                         uncached_free_page(vdata->maddr[i]);
 167                 else
 168                         printk(KERN_WARNING "mspec_close(): "
 169                                "failed to zero page %i\n",
 170                                result);
 171         }
 172
 173         if (vdata_size <= PAGE_SIZE)
 174                 kfree(vdata);
 175         else
 176                 vfree(vdata);
 177 }
 178
 179
 180 /*
 181  * mspec_nopfn
 182  *
 183  * Creates a mspec page and maps it to user space.
 184  */
 185 static unsigned long
 186 mspec_nopfn(struct vm_area_struct *vma, unsigned long address)
 187 {
 188         unsigned long paddr, maddr;
 189         unsigned long pfn;
 190         int index;
 191         struct vma_data *vdata = vma->vm_private_data;
 192
 193         index = (address - vma->vm_start) >> PAGE_SHIFT;
 194         maddr = (volatile unsigned long) vdata->maddr[index];
 195         if (maddr == 0) {
 196                 maddr = uncached_alloc_page(numa_node_id());
 197                 if (maddr == 0)
 198                         return NOPFN_OOM;
 199
 200                 spin_lock(&vdata->lock);
 201                 if (vdata->maddr[index] == 0) {
 202                         vdata->count++;
 203                         vdata->maddr[index] = maddr;
 204                 } else {
 205                         uncached_free_page(maddr);
 206                         maddr = vdata->maddr[index];
 207                 }
 208                 spin_unlock(&vdata->lock);
 209         }
 210
 211         if (vdata->type == MSPEC_FETCHOP)
 212                 paddr = TO_AMO(maddr);
 213         else
 214                 paddr = __pa(TO_CAC(maddr));
 215
 216         pfn = paddr >> PAGE_SHIFT;
 217
 218         return pfn;
 219 }
 220
 221 static struct vm_operations_struct mspec_vm_ops = {
 222         .open = mspec_open,
 223         .close = mspec_close,
 224         .nopfn = mspec_nopfn
 225 };
 226
 227 /*
 228  * mspec_mmap
 229  *
 230  * Called when mmaping the device.  Initializes the vma with a fault handler
 231  * and private data structure necessary to allocate, track, and free the
 232  * underlying pages.
 233  */
 234 static int
 235 mspec_mmap(struct file *file, struct vm_area_struct *vma, int type)
 236 {
 237         struct vma_data *vdata;
 238         int pages, vdata_size;
 239
 240         if (vma->vm_pgoff != 0)
 241                 return -EINVAL;
 242
 243         if ((vma->vm_flags & VM_SHARED) == 0)
 244                 return -EINVAL;
 245
 246         if ((vma->vm_flags & VM_WRITE) == 0)
 247                 return -EPERM;
 248
 249         pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 250         vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
 251         if (vdata_size <= PAGE_SIZE)
 252                 vdata = kmalloc(vdata_size, GFP_KERNEL);
 253         else
 254                 vdata = vmalloc(vdata_size);
 255         if (!vdata)
 256                 return -ENOMEM;
 257         memset(vdata, 0, vdata_size);
 258
 259         vdata->type = type;
 260         spin_lock_init(&vdata->lock);
 261         vdata->refcnt = ATOMIC_INIT(1);
 262         vma->vm_private_data = vdata;
 263
 264         vma->vm_flags |= (VM_IO | VM_LOCKED | VM_RESERVED | VM_PFNMAP);
 265         if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
 266                 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 267         vma->vm_ops = &mspec_vm_ops;
 268
 269         return 0;
 270 }
 271
 272 static int
 273 fetchop_mmap(struct file *file, struct vm_area_struct *vma)
 274 {
 275         return mspec_mmap(file, vma, MSPEC_FETCHOP);
 276 }
 277
 278 static int
 279 cached_mmap(struct file *file, struct vm_area_struct *vma)
 280 {
 281         return mspec_mmap(file, vma, MSPEC_CACHED);
 282 }
 283
 284 static int
 285 uncached_mmap(struct file *file, struct vm_area_struct *vma)
 286 {
 287         return mspec_mmap(file, vma, MSPEC_UNCACHED);
 288 }
 289
 290 static struct file_operations fetchop_fops = {
 291         .owner = THIS_MODULE,
 292         .mmap = fetchop_mmap
 293 };
 294
 295 static struct miscdevice fetchop_miscdev = {
 296         .minor = MISC_DYNAMIC_MINOR,
 297         .name = "sgi_fetchop",
 298         .fops = &fetchop_fops
 299 };
 300
 301 static struct file_operations cached_fops = {
 302         .owner = THIS_MODULE,
 303         .mmap = cached_mmap
 304 };
 305
 306 static struct miscdevice cached_miscdev = {
 307         .minor = MISC_DYNAMIC_MINOR,
 308         .name = "mspec_cached",
 309         .fops = &cached_fops
 310 };
 311
 312 static struct file_operations uncached_fops = {
 313         .owner = THIS_MODULE,
 314         .mmap = uncached_mmap
 315 };
 316
 317 static struct miscdevice uncached_miscdev = {
 318         .minor = MISC_DYNAMIC_MINOR,
 319         .name = "mspec_uncached",
 320         .fops = &uncached_fops
 321 };
 322
 323 /*
 324  * mspec_init
 325  *
 326  * Called at boot time to initialize the mspec facility.
 327  */
 328 static int __init
 329 mspec_init(void)
 330 {
 331         int ret;
 332         int nid;
 333
 334         /*
 335          * The fetchop device only works on SN2 hardware, uncached and cached
 336          * memory drivers should both be valid on all ia64 hardware
 337          */
 338         if (ia64_platform_is("sn2")) {
 339                 is_sn2 = 1;
 340                 if (is_shub2()) {
 341                         ret = -ENOMEM;
 342                         for_each_online_node(nid) {
 343                                 int actual_nid;
 344                                 int nasid;
 345                                 unsigned long phys;
 346
 347                                 scratch_page[nid] = uncached_alloc_page(nid);
 348                                 if (scratch_page[nid] == 0)
 349                                         goto free_scratch_pages;
 350                                 phys = __pa(scratch_page[nid]);
 351                                 nasid = get_node_number(phys);
 352                                 actual_nid = nasid_to_cnodeid(nasid);
 353                                 if (actual_nid != nid)
 354                                         goto free_scratch_pages;
 355                         }
 356                 }
 357
 358                 ret = misc_register(&fetchop_miscdev);
 359                 if (ret) {
 360                         printk(KERN_ERR
 361                                "%s: failed to register device %i\n",
 362                                FETCHOP_ID, ret);
 363                         goto free_scratch_pages;
 364                 }
 365         }
 366         ret = misc_register(&cached_miscdev);
 367         if (ret) {
 368                 printk(KERN_ERR "%s: failed to register device %i\n",
 369                        CACHED_ID, ret);
 370                 if (is_sn2)
 371                         misc_deregister(&fetchop_miscdev);
 372                 goto free_scratch_pages;
 373         }
 374         ret = misc_register(&uncached_miscdev);
 375         if (ret) {
 376                 printk(KERN_ERR "%s: failed to register device %i\n",
 377                        UNCACHED_ID, ret);
 378                 misc_deregister(&cached_miscdev);
 379                 if (is_sn2)
 380                         misc_deregister(&fetchop_miscdev);
 381                 goto free_scratch_pages;
 382         }
 383
 384         printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
 385                MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
 386                CACHED_ID, UNCACHED_ID);
 387
 388         return 0;
 389
 390  free_scratch_pages:
 391         for_each_node(nid) {
 392                 if (scratch_page[nid] != 0)
 393                         uncached_free_page(scratch_page[nid]);
 394         }
 395         return ret;
 396 }
 397
 398 static void __exit
 399 mspec_exit(void)
 400 {
 401         int nid;
 402
 403         misc_deregister(&uncached_miscdev);
 404         misc_deregister(&cached_miscdev);
 405         if (is_sn2) {
 406                 misc_deregister(&fetchop_miscdev);
 407
 408                 for_each_node(nid) {
 409                         if (scratch_page[nid] != 0)
 410                                 uncached_free_page(scratch_page[nid]);
 411                 }
 412         }
 413 }
 414
 415 module_init(mspec_init);
 416 module_exit(mspec_exit);
 417
 418 MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
 419 MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
 420 MODULE_LICENSE("GPL");