aboutsummaryrefslogtreecommitdiff
path: root/drivers/char/mspec.c
blob: 5426b1e5595f7cef7877ae7d697758b942bee182 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
/*
 * Copyright (C) 2001-2006 Silicon Graphics, Inc.  All rights
 * reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License
 * as published by the Free Software Foundation.
 */

/*
 * SN Platform Special Memory (mspec) Support
 *
 * This driver exports the SN special memory (mspec) facility to user
 * processes.
 * There are three types of memory made available thru this driver:
 * fetchops, uncached and cached.
 *
 * Fetchops are atomic memory operations that are implemented in the
 * memory controller on SGI SN hardware.
 *
 * Uncached are used for memory write combining feature of the ia64
 * cpu.
 *
 * Cached are used for areas of memory that are used as cached addresses
 * on our partition and used as uncached addresses from other partitions.
 * Due to a design constraint of the SN2 Shub, you can not have processors
 * on the same FSB perform both a cached and uncached reference to the
 * same cache line.  These special memory cached regions prevent the
 * kernel from ever dropping in a TLB entry and therefore prevent the
 * processor from ever speculating a cache line from this page.
 */

#include <linux/config.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/numa.h>
#include <asm/page.h>
#include <asm/system.h>
#include <asm/pgtable.h>
#include <asm/atomic.h>
#include <asm/tlbflush.h>
#include <asm/uncached.h>
#include <asm/sn/addrs.h>
#include <asm/sn/arch.h>
#include <asm/sn/mspec.h>
#include <asm/sn/sn_cpuid.h>
#include <asm/sn/io.h>
#include <asm/sn/bte.h>
#include <asm/sn/shubio.h>


#define FETCHOP_ID	"SGI Fetchop,"
#define CACHED_ID	"Cached,"
#define UNCACHED_ID	"Uncached"
#define REVISION	"4.0"
#define MSPEC_BASENAME	"mspec"

/*
 * Page types allocated by the device.
 */
enum {
	MSPEC_FETCHOP = 1,
	MSPEC_CACHED,
	MSPEC_UNCACHED
};

static int is_sn2;

/*
 * One of these structures is allocated when an mspec region is mmaped. The
 * structure is pointed to by the vma->vm_private_data field in the vma struct.
 * This structure is used to record the addresses of the mspec pages.
 */
struct vma_data {
	atomic_t refcnt;	/* Number of vmas sharing the data. */
	spinlock_t lock;	/* Serialize access to the vma. */
	int count;		/* Number of pages allocated. */
	int type;		/* Type of pages allocated. */
	unsigned long maddr[0];	/* Array of MSPEC addresses. */
};

/* used on shub2 to clear FOP cache in the HUB */
static unsigned long scratch_page[MAX_NUMNODES];
#define SH2_AMO_CACHE_ENTRIES	4

static inline int
mspec_zero_block(unsigned long addr, int len)
{
	int status;

	if (is_sn2) {
		if (is_shub2()) {
			int nid;
			void *p;
			int i;

			nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
			p = (void *)TO_AMO(scratch_page[nid]);

			for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
				FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
				p += FETCHOP_VAR_SIZE;
			}
		}

		status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
				  BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
	} else {
		memset((char *) addr, 0, len);
		status = 0;
	}
	return status;
}

/*
 * mspec_open
 *
 * Called when a device mapping is created by a means other than mmap
 * (via fork, etc.).  Increments the reference count on the underlying
 * mspec data so it is not freed prematurely.
 */
static void
mspec_open(struct vm_area_struct *vma)
{
	struct vma_data *vdata;

	vdata = vma->vm_private_data;
	atomic_inc(&vdata->refcnt);
}

/*
 * mspec_close
 *
 * Called when unmapping a device mapping. Frees all mspec pages
 * belonging to the vma.
 */
static void
mspec_close(struct vm_area_struct *vma)
{
	struct vma_data *vdata;
	int i, pages, result, vdata_size;

	vdata = vma->vm_private_data;
	if (!atomic_dec_and_test(&vdata->refcnt))
		return;

	pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
	vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
	for (i = 0; i < pages; i++) {
		if (vdata->maddr[i] == 0)
			continue;
		/*
		 * Clear the page before sticking it back
		 * into the pool.
		 */
		result = mspec_zero_block(vdata->maddr[i], PAGE_SIZE);
		if (!result)
			uncached_free_page(vdata->maddr[i]);
		else
			printk(KERN_WARNING "mspec_close(): "
			       "failed to zero page %i\n",
			       result);
	}

	if (vdata_size <= PAGE_SIZE)
		kfree(vdata);
	else
		vfree(vdata);
}


/*
 * mspec_nopfn
 *
 * Creates a mspec page and maps it to user space.
 */
static unsigned long
mspec_nopfn(struct vm_area_struct *vma, unsigned long address)
{
	unsigned long paddr, maddr;
	unsigned long pfn;
	int index;
	struct vma_data *vdata = vma->vm_private_data;

	index = (address - vma->vm_start) >> PAGE_SHIFT;
	maddr = (volatile unsigned long) vdata->maddr[index];
	if (maddr == 0) {
		maddr = uncached_alloc_page(numa_node_id());
		if (maddr == 0)
			return NOPFN_OOM;

		spin_lock(&vdata->lock);
		if (vdata->maddr[index] == 0) {
			vdata->count++;
			vdata->maddr[index] = maddr;
		} else {
			uncached_free_page(maddr);
			maddr = vdata->maddr[index];
		}
		spin_unlock(&vdata->lock);
	}

	if (vdata->type == MSPEC_FETCHOP)
		paddr = TO_AMO(maddr);
	else
		paddr = __pa(TO_CAC(maddr));

	pfn = paddr >> PAGE_SHIFT;

	return pfn;
}

static struct vm_operations_struct mspec_vm_ops = {
	.open = mspec_open,
	.close = mspec_close,
	.nopfn = mspec_nopfn
};

/*
 * mspec_mmap
 *
 * Called when mmaping the device.  Initializes the vma with a fault handler
 * and private data structure necessary to allocate, track, and free the
 * underlying pages.
 */
static int
mspec_mmap(struct file *file, struct vm_area_struct *vma, int type)
{
	struct vma_data *vdata;
	int pages, vdata_size;

	if (vma->vm_pgoff != 0)
		return -EINVAL;

	if ((vma->vm_flags & VM_SHARED) == 0)
		return -EINVAL;

	if ((vma->vm_flags & VM_WRITE) == 0)
		return -EPERM;

	pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
	vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
	if (vdata_size <= PAGE_SIZE)
		vdata = kmalloc(vdata_size, GFP_KERNEL);
	else
		vdata = vmalloc(vdata_size);
	if (!vdata)
		return -ENOMEM;
	memset(vdata, 0, vdata_size);

	vdata->type = type;
	spin_lock_init(&vdata->lock);
	vdata->refcnt = ATOMIC_INIT(1);
	vma->vm_private_data = vdata;

	vma->vm_flags |= (VM_IO | VM_LOCKED | VM_RESERVED | VM_PFNMAP);
	if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
	vma->vm_ops = &mspec_vm_ops;

	return 0;
}

static int
fetchop_mmap(struct file *file, struct vm_area_struct *vma)
{
	return mspec_mmap(file, vma, MSPEC_FETCHOP);
}

static int
cached_mmap(struct file *file, struct vm_area_struct *vma)
{
	return mspec_mmap(file, vma, MSPEC_CACHED);
}

static int
uncached_mmap(struct file *file, struct vm_area_struct *vma)
{
	return mspec_mmap(file, vma, MSPEC_UNCACHED);
}

static struct file_operations fetchop_fops = {
	.owner = THIS_MODULE,
	.mmap = fetchop_mmap
};

static struct miscdevice fetchop_miscdev = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = "sgi_fetchop",
	.fops = &fetchop_fops
};

static struct file_operations cached_fops = {
	.owner = THIS_MODULE,
	.mmap = cached_mmap
};

static struct miscdevice cached_miscdev = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = "mspec_cached",
	.fops = &cached_fops
};

static struct file_operations uncached_fops = {
	.owner = THIS_MODULE,
	.mmap = uncached_mmap
};

static struct miscdevice uncached_miscdev = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = "mspec_uncached",
	.fops = &uncached_fops
};

/*
 * mspec_init
 *
 * Called at boot time to initialize the mspec facility.
 */
static int __init
mspec_init(void)
{
	int ret;
	int nid;

	/*
	 * The fetchop device only works on SN2 hardware, uncached and cached
	 * memory drivers should both be valid on all ia64 hardware
	 */
	if (ia64_platform_is("sn2")) {
		is_sn2 = 1;
		if (is_shub2()) {
			ret = -ENOMEM;
			for_each_online_node(nid) {
				int actual_nid;
				int nasid;
				unsigned long phys;

				scratch_page[nid] = uncached_alloc_page(nid);
				if (scratch_page[nid] == 0)
					goto free_scratch_pages;
				phys = __pa(scratch_page[nid]);
				nasid = get_node_number(phys);
				actual_nid = nasid_to_cnodeid(nasid);
				if (actual_nid != nid)
					goto free_scratch_pages;
			}
		}

		ret = misc_register(&fetchop_miscdev);
		if (ret) {
			printk(KERN_ERR
			       "%s: failed to register device %i\n",
			       FETCHOP_ID, ret);
			goto free_scratch_pages;
		}
	}
	ret = misc_register(&cached_miscdev);
	if (ret) {
		printk(KERN_ERR "%s: failed to register device %i\n",
		       CACHED_ID, ret);
		if (is_sn2)
			misc_deregister(&fetchop_miscdev);
		goto free_scratch_pages;
	}
	ret = misc_register(&uncached_miscdev);
	if (ret) {
		printk(KERN_ERR "%s: failed to register device %i\n",
		       UNCACHED_ID, ret);
		misc_deregister(&cached_miscdev);
		if (is_sn2)
			misc_deregister(&fetchop_miscdev);
		goto free_scratch_pages;
	}

	printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
	       MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
	       CACHED_ID, UNCACHED_ID);

	return 0;

 free_scratch_pages:
	for_each_node(nid) {
		if (scratch_page[nid] != 0)
			uncached_free_page(scratch_page[nid]);
	}
	return ret;
}

static void __exit
mspec_exit(void)
{
	int nid;

	misc_deregister(&uncached_miscdev);
	misc_deregister(&cached_miscdev);
	if (is_sn2) {
		misc_deregister(&fetchop_miscdev);

		for_each_node(nid) {
			if (scratch_page[nid] != 0)
				uncached_free_page(scratch_page[nid]);
		}
	}
}

module_init(mspec_init);
module_exit(mspec_exit);

MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
MODULE_LICENSE("GPL");