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 #ifdef CONFIG_SGI_SN
  76 static int is_sn2;
  77 #else
  78 #define is_sn2          0
  79 #endif
  80
  81 /*
  82  * One of these structures is allocated when an mspec region is mmaped. The
  83  * structure is pointed to by the vma->vm_private_data field in the vma struct.
  84  * This structure is used to record the addresses of the mspec pages.
  85  */
  86 struct vma_data {
  87         atomic_t refcnt;        /* Number of vmas sharing the data. */
  88         spinlock_t lock;        /* Serialize access to the vma. */
  89         int count;              /* Number of pages allocated. */
  90         int type;               /* Type of pages allocated. */
  91         unsigned long maddr[0]; /* Array of MSPEC addresses. */
  92 };
  93
  94 /* used on shub2 to clear FOP cache in the HUB */
  95 static unsigned long scratch_page[MAX_NUMNODES];
  96 #define SH2_AMO_CACHE_ENTRIES   4
  97
  98 static inline int
  99 mspec_zero_block(unsigned long addr, int len)
 100 {
 101         int status;
 102
 103         if (is_sn2) {
 104                 if (is_shub2()) {
 105                         int nid;
 106                         void *p;
 107                         int i;
 108
 109                         nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
 110                         p = (void *)TO_AMO(scratch_page[nid]);
 111
 112                         for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
 113                                 FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
 114                                 p += FETCHOP_VAR_SIZE;
 115                         }
 116                 }
 117
 118                 status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
 119                                   BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
 120         } else {
 121                 memset((char *) addr, 0, len);
 122                 status = 0;
 123         }
 124         return status;
 125 }
 126
 127 /*
 128  * mspec_open
 129  *
 130  * Called when a device mapping is created by a means other than mmap
 131  * (via fork, etc.).  Increments the reference count on the underlying
 132  * mspec data so it is not freed prematurely.
 133  */
 134 static void
 135 mspec_open(struct vm_area_struct *vma)
 136 {
 137         struct vma_data *vdata;
 138
 139         vdata = vma->vm_private_data;
 140         atomic_inc(&vdata->refcnt);
 141 }
 142
 143 /*
 144  * mspec_close
 145  *
 146  * Called when unmapping a device mapping. Frees all mspec pages
 147  * belonging to the vma.
 148  */
 149 static void
 150 mspec_close(struct vm_area_struct *vma)
 151 {
 152         struct vma_data *vdata;
 153         int i, pages, result, vdata_size;
 154
 155         vdata = vma->vm_private_data;
 156         if (!atomic_dec_and_test(&vdata->refcnt))
 157                 return;
 158
 159         pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 160         vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
 161         for (i = 0; i < pages; i++) {
 162                 if (vdata->maddr[i] == 0)
 163                         continue;
 164                 /*
 165                  * Clear the page before sticking it back
 166                  * into the pool.
 167                  */
 168                 result = mspec_zero_block(vdata->maddr[i], PAGE_SIZE);
 169                 if (!result)
 170                         uncached_free_page(vdata->maddr[i]);
 171                 else
 172                         printk(KERN_WARNING "mspec_close(): "
 173                                "failed to zero page %i\n",
 174                                result);
 175         }
 176
 177         if (vdata_size <= PAGE_SIZE)
 178                 kfree(vdata);
 179         else
 180                 vfree(vdata);
 181 }
 182
 183
 184 /*
 185  * mspec_nopfn
 186  *
 187  * Creates a mspec page and maps it to user space.
 188  */
 189 static unsigned long
 190 mspec_nopfn(struct vm_area_struct *vma, unsigned long address)
 191 {
 192         unsigned long paddr, maddr;
 193         unsigned long pfn;
 194         int index;
 195         struct vma_data *vdata = vma->vm_private_data;
 196
 197         index = (address - vma->vm_start) >> PAGE_SHIFT;
 198         maddr = (volatile unsigned long) vdata->maddr[index];
 199         if (maddr == 0) {
 200                 maddr = uncached_alloc_page(numa_node_id());
 201                 if (maddr == 0)
 202                         return NOPFN_OOM;
 203
 204                 spin_lock(&vdata->lock);
 205                 if (vdata->maddr[index] == 0) {
 206                         vdata->count++;
 207                         vdata->maddr[index] = maddr;
 208                 } else {
 209                         uncached_free_page(maddr);
 210                         maddr = vdata->maddr[index];
 211                 }
 212                 spin_unlock(&vdata->lock);
 213         }
 214
 215         if (vdata->type == MSPEC_FETCHOP)
 216                 paddr = TO_AMO(maddr);
 217         else
 218                 paddr = maddr & ~__IA64_UNCACHED_OFFSET;
 219
 220         pfn = paddr >> PAGE_SHIFT;
 221
 222         return pfn;
 223 }
 224
 225 static struct vm_operations_struct mspec_vm_ops = {
 226         .open = mspec_open,
 227         .close = mspec_close,
 228         .nopfn = mspec_nopfn
 229 };
 230
 231 /*
 232  * mspec_mmap
 233  *
 234  * Called when mmaping the device.  Initializes the vma with a fault handler
 235  * and private data structure necessary to allocate, track, and free the
 236  * underlying pages.
 237  */
 238 static int
 239 mspec_mmap(struct file *file, struct vm_area_struct *vma, int type)
 240 {
 241         struct vma_data *vdata;
 242         int pages, vdata_size;
 243
 244         if (vma->vm_pgoff != 0)
 245                 return -EINVAL;
 246
 247         if ((vma->vm_flags & VM_SHARED) == 0)
 248                 return -EINVAL;
 249
 250         if ((vma->vm_flags & VM_WRITE) == 0)
 251                 return -EPERM;
 252
 253         pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 254         vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
 255         if (vdata_size <= PAGE_SIZE)
 256                 vdata = kmalloc(vdata_size, GFP_KERNEL);
 257         else
 258                 vdata = vmalloc(vdata_size);
 259         if (!vdata)
 260                 return -ENOMEM;
 261         memset(vdata, 0, vdata_size);
 262
 263         vdata->type = type;
 264         spin_lock_init(&vdata->lock);
 265         vdata->refcnt = ATOMIC_INIT(1);
 266         vma->vm_private_data = vdata;
 267
 268         vma->vm_flags |= (VM_IO | VM_LOCKED | VM_RESERVED | VM_PFNMAP);
 269         if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
 270                 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 271         vma->vm_ops = &mspec_vm_ops;
 272
 273         return 0;
 274 }
 275
 276 static int
 277 fetchop_mmap(struct file *file, struct vm_area_struct *vma)
 278 {
 279         return mspec_mmap(file, vma, MSPEC_FETCHOP);
 280 }
 281
 282 static int
 283 cached_mmap(struct file *file, struct vm_area_struct *vma)
 284 {
 285         return mspec_mmap(file, vma, MSPEC_CACHED);
 286 }
 287
 288 static int
 289 uncached_mmap(struct file *file, struct vm_area_struct *vma)
 290 {
 291         return mspec_mmap(file, vma, MSPEC_UNCACHED);
 292 }
 293
 294 static struct file_operations fetchop_fops = {
 295         .owner = THIS_MODULE,
 296         .mmap = fetchop_mmap
 297 };
 298
 299 static struct miscdevice fetchop_miscdev = {
 300         .minor = MISC_DYNAMIC_MINOR,
 301         .name = "sgi_fetchop",
 302         .fops = &fetchop_fops
 303 };
 304
 305 static struct file_operations cached_fops = {
 306         .owner = THIS_MODULE,
 307         .mmap = cached_mmap
 308 };
 309
 310 static struct miscdevice cached_miscdev = {
 311         .minor = MISC_DYNAMIC_MINOR,
 312         .name = "mspec_cached",
 313         .fops = &cached_fops
 314 };
 315
 316 static struct file_operations uncached_fops = {
 317         .owner = THIS_MODULE,
 318         .mmap = uncached_mmap
 319 };
 320
 321 static struct miscdevice uncached_miscdev = {
 322         .minor = MISC_DYNAMIC_MINOR,
 323         .name = "mspec_uncached",
 324         .fops = &uncached_fops
 325 };
 326
 327 /*
 328  * mspec_init
 329  *
 330  * Called at boot time to initialize the mspec facility.
 331  */
 332 static int __init
 333 mspec_init(void)
 334 {
 335         int ret;
 336         int nid;
 337
 338         /*
 339          * The fetchop device only works on SN2 hardware, uncached and cached
 340          * memory drivers should both be valid on all ia64 hardware
 341          */
 342 #ifdef CONFIG_SGI_SN
 343         if (ia64_platform_is("sn2")) {
 344                 is_sn2 = 1;
 345                 if (is_shub2()) {
 346                         ret = -ENOMEM;
 347                         for_each_online_node(nid) {
 348                                 int actual_nid;
 349                                 int nasid;
 350                                 unsigned long phys;
 351
 352                                 scratch_page[nid] = uncached_alloc_page(nid);
 353                                 if (scratch_page[nid] == 0)
 354                                         goto free_scratch_pages;
 355                                 phys = __pa(scratch_page[nid]);
 356                                 nasid = get_node_number(phys);
 357                                 actual_nid = nasid_to_cnodeid(nasid);
 358                                 if (actual_nid != nid)
 359                                         goto free_scratch_pages;
 360                         }
 361                 }
 362
 363                 ret = misc_register(&fetchop_miscdev);
 364                 if (ret) {
 365                         printk(KERN_ERR
 366                                "%s: failed to register device %i\n",
 367                                FETCHOP_ID, ret);
 368                         goto free_scratch_pages;
 369                 }
 370         }
 371 #endif
 372         ret = misc_register(&cached_miscdev);
 373         if (ret) {
 374                 printk(KERN_ERR "%s: failed to register device %i\n",
 375                        CACHED_ID, ret);
 376                 if (is_sn2)
 377                         misc_deregister(&fetchop_miscdev);
 378                 goto free_scratch_pages;
 379         }
 380         ret = misc_register(&uncached_miscdev);
 381         if (ret) {
 382                 printk(KERN_ERR "%s: failed to register device %i\n",
 383                        UNCACHED_ID, ret);
 384                 misc_deregister(&cached_miscdev);
 385                 if (is_sn2)
 386                         misc_deregister(&fetchop_miscdev);
 387                 goto free_scratch_pages;
 388         }
 389
 390         printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
 391                MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
 392                CACHED_ID, UNCACHED_ID);
 393
 394         return 0;
 395
 396  free_scratch_pages:
 397         for_each_node(nid) {
 398                 if (scratch_page[nid] != 0)
 399                         uncached_free_page(scratch_page[nid]);
 400         }
 401         return ret;
 402 }
 403
 404 static void __exit
 405 mspec_exit(void)
 406 {
 407         int nid;
 408
 409         misc_deregister(&uncached_miscdev);
 410         misc_deregister(&cached_miscdev);
 411         if (is_sn2) {
 412                 misc_deregister(&fetchop_miscdev);
 413
 414                 for_each_node(nid) {
 415                         if (scratch_page[nid] != 0)
 416                                 uncached_free_page(scratch_page[nid]);
 417                 }
 418         }
 419 }
 420
 421 module_init(mspec_init);
 422 module_exit(mspec_exit);
 423
 424 MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
 425 MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
 426 MODULE_LICENSE("GPL");