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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 <asm/page.h>
47#include <asm/pgtable.h>
48#include <linux/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 */
69enum mspec_page_type {
70 MSPEC_FETCHOP = 1,
71 MSPEC_CACHED,
72 MSPEC_UNCACHED
73};
74
75#ifdef CONFIG_SGI_SN
76static 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 * This structure is shared by all vma's that are split off from the
86 * original vma when split_vma()'s are done.
87 *
88 * The refcnt is incremented atomically because mm->mmap_sem does not
89 * protect in fork case where multiple tasks share the vma_data.
90 */
91struct vma_data {
92 atomic_t refcnt; /* Number of vmas sharing the data. */
93 spinlock_t lock; /* Serialize access to this structure. */
94 int count; /* Number of pages allocated. */
95 enum mspec_page_type type; /* Type of pages allocated. */
96 unsigned long vm_start; /* Original (unsplit) base. */
97 unsigned long vm_end; /* Original (unsplit) end. */
98 unsigned long maddr[0]; /* Array of MSPEC addresses. */
99};
100
101/* used on shub2 to clear FOP cache in the HUB */
102static unsigned long scratch_page[MAX_NUMNODES];
103#define SH2_AMO_CACHE_ENTRIES 4
104
105static inline int
106mspec_zero_block(unsigned long addr, int len)
107{
108 int status;
109
110 if (is_sn2) {
111 if (is_shub2()) {
112 int nid;
113 void *p;
114 int i;
115
116 nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
117 p = (void *)TO_AMO(scratch_page[nid]);
118
119 for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
120 FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
121 p += FETCHOP_VAR_SIZE;
122 }
123 }
124
125 status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
126 BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
127 } else {
128 memset((char *) addr, 0, len);
129 status = 0;
130 }
131 return status;
132}
133
134/*
135 * mspec_open
136 *
137 * Called when a device mapping is created by a means other than mmap
138 * (via fork, munmap, etc.). Increments the reference count on the
139 * underlying mspec data so it is not freed prematurely.
140 */
141static void
142mspec_open(struct vm_area_struct *vma)
143{
144 struct vma_data *vdata;
145
146 vdata = vma->vm_private_data;
147 atomic_inc(&vdata->refcnt);
148}
149
150/*
151 * mspec_close
152 *
153 * Called when unmapping a device mapping. Frees all mspec pages
154 * belonging to all the vma's sharing this vma_data structure.
155 */
156static void
157mspec_close(struct vm_area_struct *vma)
158{
159 struct vma_data *vdata;
160 int index, last_index;
161 unsigned long my_page;
162
163 vdata = vma->vm_private_data;
164
165 if (!atomic_dec_and_test(&vdata->refcnt))
166 return;
167
168 last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
169 for (index = 0; index < last_index; index++) {
170 if (vdata->maddr[index] == 0)
171 continue;
172 /*
173 * Clear the page before sticking it back
174 * into the pool.
175 */
176 my_page = vdata->maddr[index];
177 vdata->maddr[index] = 0;
178 if (!mspec_zero_block(my_page, PAGE_SIZE))
179 uncached_free_page(my_page, 1);
180 else
181 printk(KERN_WARNING "mspec_close(): "
182 "failed to zero page %ld\n", my_page);
183 }
184
185 kvfree(vdata);
186}
187
188/*
189 * mspec_fault
190 *
191 * Creates a mspec page and maps it to user space.
192 */
193static int
194mspec_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
195{
196 unsigned long paddr, maddr;
197 unsigned long pfn;
198 pgoff_t index = vmf->pgoff;
199 struct vma_data *vdata = vma->vm_private_data;
200
201 maddr = (volatile unsigned long) vdata->maddr[index];
202 if (maddr == 0) {
203 maddr = uncached_alloc_page(numa_node_id(), 1);
204 if (maddr == 0)
205 return VM_FAULT_OOM;
206
207 spin_lock(&vdata->lock);
208 if (vdata->maddr[index] == 0) {
209 vdata->count++;
210 vdata->maddr[index] = maddr;
211 } else {
212 uncached_free_page(maddr, 1);
213 maddr = vdata->maddr[index];
214 }
215 spin_unlock(&vdata->lock);
216 }
217
218 if (vdata->type == MSPEC_FETCHOP)
219 paddr = TO_AMO(maddr);
220 else
221 paddr = maddr & ~__IA64_UNCACHED_OFFSET;
222
223 pfn = paddr >> PAGE_SHIFT;
224
225 /*
226 * vm_insert_pfn can fail with -EBUSY, but in that case it will
227 * be because another thread has installed the pte first, so it
228 * is no problem.
229 */
230 vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);
231
232 return VM_FAULT_NOPAGE;
233}
234
235static const struct vm_operations_struct mspec_vm_ops = {
236 .open = mspec_open,
237 .close = mspec_close,
238 .fault = mspec_fault,
239};
240
241/*
242 * mspec_mmap
243 *
244 * Called when mmapping the device. Initializes the vma with a fault handler
245 * and private data structure necessary to allocate, track, and free the
246 * underlying pages.
247 */
248static int
249mspec_mmap(struct file *file, struct vm_area_struct *vma,
250 enum mspec_page_type type)
251{
252 struct vma_data *vdata;
253 int pages, vdata_size;
254
255 if (vma->vm_pgoff != 0)
256 return -EINVAL;
257
258 if ((vma->vm_flags & VM_SHARED) == 0)
259 return -EINVAL;
260
261 if ((vma->vm_flags & VM_WRITE) == 0)
262 return -EPERM;
263
264 pages = vma_pages(vma);
265 vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
266 if (vdata_size <= PAGE_SIZE)
267 vdata = kzalloc(vdata_size, GFP_KERNEL);
268 else
269 vdata = vzalloc(vdata_size);
270 if (!vdata)
271 return -ENOMEM;
272
273 vdata->vm_start = vma->vm_start;
274 vdata->vm_end = vma->vm_end;
275 vdata->type = type;
276 spin_lock_init(&vdata->lock);
277 atomic_set(&vdata->refcnt, 1);
278 vma->vm_private_data = vdata;
279
280 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
281 if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
282 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
283 vma->vm_ops = &mspec_vm_ops;
284
285 return 0;
286}
287
288static int
289fetchop_mmap(struct file *file, struct vm_area_struct *vma)
290{
291 return mspec_mmap(file, vma, MSPEC_FETCHOP);
292}
293
294static int
295cached_mmap(struct file *file, struct vm_area_struct *vma)
296{
297 return mspec_mmap(file, vma, MSPEC_CACHED);
298}
299
300static int
301uncached_mmap(struct file *file, struct vm_area_struct *vma)
302{
303 return mspec_mmap(file, vma, MSPEC_UNCACHED);
304}
305
306static const struct file_operations fetchop_fops = {
307 .owner = THIS_MODULE,
308 .mmap = fetchop_mmap,
309 .llseek = noop_llseek,
310};
311
312static struct miscdevice fetchop_miscdev = {
313 .minor = MISC_DYNAMIC_MINOR,
314 .name = "sgi_fetchop",
315 .fops = &fetchop_fops
316};
317
318static const struct file_operations cached_fops = {
319 .owner = THIS_MODULE,
320 .mmap = cached_mmap,
321 .llseek = noop_llseek,
322};
323
324static struct miscdevice cached_miscdev = {
325 .minor = MISC_DYNAMIC_MINOR,
326 .name = "mspec_cached",
327 .fops = &cached_fops
328};
329
330static const struct file_operations uncached_fops = {
331 .owner = THIS_MODULE,
332 .mmap = uncached_mmap,
333 .llseek = noop_llseek,
334};
335
336static struct miscdevice uncached_miscdev = {
337 .minor = MISC_DYNAMIC_MINOR,
338 .name = "mspec_uncached",
339 .fops = &uncached_fops
340};
341
342/*
343 * mspec_init
344 *
345 * Called at boot time to initialize the mspec facility.
346 */
347static int __init
348mspec_init(void)
349{
350 int ret;
351 int nid;
352
353 /*
354 * The fetchop device only works on SN2 hardware, uncached and cached
355 * memory drivers should both be valid on all ia64 hardware
356 */
357#ifdef CONFIG_SGI_SN
358 if (ia64_platform_is("sn2")) {
359 is_sn2 = 1;
360 if (is_shub2()) {
361 ret = -ENOMEM;
362 for_each_node_state(nid, N_ONLINE) {
363 int actual_nid;
364 int nasid;
365 unsigned long phys;
366
367 scratch_page[nid] = uncached_alloc_page(nid, 1);
368 if (scratch_page[nid] == 0)
369 goto free_scratch_pages;
370 phys = __pa(scratch_page[nid]);
371 nasid = get_node_number(phys);
372 actual_nid = nasid_to_cnodeid(nasid);
373 if (actual_nid != nid)
374 goto free_scratch_pages;
375 }
376 }
377
378 ret = misc_register(&fetchop_miscdev);
379 if (ret) {
380 printk(KERN_ERR
381 "%s: failed to register device %i\n",
382 FETCHOP_ID, ret);
383 goto free_scratch_pages;
384 }
385 }
386#endif
387 ret = misc_register(&cached_miscdev);
388 if (ret) {
389 printk(KERN_ERR "%s: failed to register device %i\n",
390 CACHED_ID, ret);
391 if (is_sn2)
392 misc_deregister(&fetchop_miscdev);
393 goto free_scratch_pages;
394 }
395 ret = misc_register(&uncached_miscdev);
396 if (ret) {
397 printk(KERN_ERR "%s: failed to register device %i\n",
398 UNCACHED_ID, ret);
399 misc_deregister(&cached_miscdev);
400 if (is_sn2)
401 misc_deregister(&fetchop_miscdev);
402 goto free_scratch_pages;
403 }
404
405 printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
406 MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
407 CACHED_ID, UNCACHED_ID);
408
409 return 0;
410
411 free_scratch_pages:
412 for_each_node(nid) {
413 if (scratch_page[nid] != 0)
414 uncached_free_page(scratch_page[nid], 1);
415 }
416 return ret;
417}
418
419static void __exit
420mspec_exit(void)
421{
422 int nid;
423
424 misc_deregister(&uncached_miscdev);
425 misc_deregister(&cached_miscdev);
426 if (is_sn2) {
427 misc_deregister(&fetchop_miscdev);
428
429 for_each_node(nid) {
430 if (scratch_page[nid] != 0)
431 uncached_free_page(scratch_page[nid], 1);
432 }
433 }
434}
435
436module_init(mspec_init);
437module_exit(mspec_exit);
438
439MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
440MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
441MODULE_LICENSE("GPL");