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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 */
70enum mspec_page_type {
71 MSPEC_FETCHOP = 1,
72 MSPEC_CACHED,
73 MSPEC_UNCACHED
74};
75
76#ifdef CONFIG_SGI_SN
77static 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 */
92struct 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 */
103static unsigned long scratch_page[MAX_NUMNODES];
104#define SH2_AMO_CACHE_ENTRIES 4
105
106static inline int
107mspec_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 */
142static void
143mspec_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 */
157static void
158mspec_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 */
194static int
195mspec_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
236static 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 */
249static int
250mspec_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
289static int
290fetchop_mmap(struct file *file, struct vm_area_struct *vma)
291{
292 return mspec_mmap(file, vma, MSPEC_FETCHOP);
293}
294
295static int
296cached_mmap(struct file *file, struct vm_area_struct *vma)
297{
298 return mspec_mmap(file, vma, MSPEC_CACHED);
299}
300
301static int
302uncached_mmap(struct file *file, struct vm_area_struct *vma)
303{
304 return mspec_mmap(file, vma, MSPEC_UNCACHED);
305}
306
307static const struct file_operations fetchop_fops = {
308 .owner = THIS_MODULE,
309 .mmap = fetchop_mmap,
310 .llseek = noop_llseek,
311};
312
313static struct miscdevice fetchop_miscdev = {
314 .minor = MISC_DYNAMIC_MINOR,
315 .name = "sgi_fetchop",
316 .fops = &fetchop_fops
317};
318
319static const struct file_operations cached_fops = {
320 .owner = THIS_MODULE,
321 .mmap = cached_mmap,
322 .llseek = noop_llseek,
323};
324
325static struct miscdevice cached_miscdev = {
326 .minor = MISC_DYNAMIC_MINOR,
327 .name = "mspec_cached",
328 .fops = &cached_fops
329};
330
331static const struct file_operations uncached_fops = {
332 .owner = THIS_MODULE,
333 .mmap = uncached_mmap,
334 .llseek = noop_llseek,
335};
336
337static 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 */
348static int __init
349mspec_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
420static void __exit
421mspec_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
437module_init(mspec_init);
438module_exit(mspec_exit);
439
440MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
441MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
442MODULE_LICENSE("GPL");