xref: /openbmc/linux/drivers/char/mspec.c (revision 22246614)
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/system.h>
48 #include <asm/pgtable.h>
49 #include <asm/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  */
70 enum mspec_page_type {
71 	MSPEC_FETCHOP = 1,
72 	MSPEC_CACHED,
73 	MSPEC_UNCACHED
74 };
75 
76 #ifdef CONFIG_SGI_SN
77 static 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  */
92 struct vma_data {
93 	atomic_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 	int flags;		/* See VMD_xxx below. */
98 	unsigned long vm_start;	/* Original (unsplit) base. */
99 	unsigned long vm_end;	/* Original (unsplit) end. */
100 	unsigned long maddr[0];	/* Array of MSPEC addresses. */
101 };
102 
103 #define VMD_VMALLOCED 0x1	/* vmalloc'd rather than kmalloc'd */
104 
105 /* used on shub2 to clear FOP cache in the HUB */
106 static unsigned long scratch_page[MAX_NUMNODES];
107 #define SH2_AMO_CACHE_ENTRIES	4
108 
109 static inline int
110 mspec_zero_block(unsigned long addr, int len)
111 {
112 	int status;
113 
114 	if (is_sn2) {
115 		if (is_shub2()) {
116 			int nid;
117 			void *p;
118 			int i;
119 
120 			nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
121 			p = (void *)TO_AMO(scratch_page[nid]);
122 
123 			for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
124 				FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
125 				p += FETCHOP_VAR_SIZE;
126 			}
127 		}
128 
129 		status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
130 				  BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
131 	} else {
132 		memset((char *) addr, 0, len);
133 		status = 0;
134 	}
135 	return status;
136 }
137 
138 /*
139  * mspec_open
140  *
141  * Called when a device mapping is created by a means other than mmap
142  * (via fork, munmap, etc.).  Increments the reference count on the
143  * underlying mspec data so it is not freed prematurely.
144  */
145 static void
146 mspec_open(struct vm_area_struct *vma)
147 {
148 	struct vma_data *vdata;
149 
150 	vdata = vma->vm_private_data;
151 	atomic_inc(&vdata->refcnt);
152 }
153 
154 /*
155  * mspec_close
156  *
157  * Called when unmapping a device mapping. Frees all mspec pages
158  * belonging to all the vma's sharing this vma_data structure.
159  */
160 static void
161 mspec_close(struct vm_area_struct *vma)
162 {
163 	struct vma_data *vdata;
164 	int index, last_index;
165 	unsigned long my_page;
166 
167 	vdata = vma->vm_private_data;
168 
169 	if (!atomic_dec_and_test(&vdata->refcnt))
170 		return;
171 
172 	last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
173 	for (index = 0; index < last_index; index++) {
174 		if (vdata->maddr[index] == 0)
175 			continue;
176 		/*
177 		 * Clear the page before sticking it back
178 		 * into the pool.
179 		 */
180 		my_page = vdata->maddr[index];
181 		vdata->maddr[index] = 0;
182 		if (!mspec_zero_block(my_page, PAGE_SIZE))
183 			uncached_free_page(my_page, 1);
184 		else
185 			printk(KERN_WARNING "mspec_close(): "
186 			       "failed to zero page %ld\n", my_page);
187 	}
188 
189 	if (vdata->flags & VMD_VMALLOCED)
190 		vfree(vdata);
191 	else
192 		kfree(vdata);
193 }
194 
195 /*
196  * mspec_nopfn
197  *
198  * Creates a mspec page and maps it to user space.
199  */
200 static unsigned long
201 mspec_nopfn(struct vm_area_struct *vma, unsigned long address)
202 {
203 	unsigned long paddr, maddr;
204 	unsigned long pfn;
205 	int index;
206 	struct vma_data *vdata = vma->vm_private_data;
207 
208 	BUG_ON(address < vdata->vm_start || address >= vdata->vm_end);
209 	index = (address - vdata->vm_start) >> PAGE_SHIFT;
210 	maddr = (volatile unsigned long) vdata->maddr[index];
211 	if (maddr == 0) {
212 		maddr = uncached_alloc_page(numa_node_id(), 1);
213 		if (maddr == 0)
214 			return NOPFN_OOM;
215 
216 		spin_lock(&vdata->lock);
217 		if (vdata->maddr[index] == 0) {
218 			vdata->count++;
219 			vdata->maddr[index] = maddr;
220 		} else {
221 			uncached_free_page(maddr, 1);
222 			maddr = vdata->maddr[index];
223 		}
224 		spin_unlock(&vdata->lock);
225 	}
226 
227 	if (vdata->type == MSPEC_FETCHOP)
228 		paddr = TO_AMO(maddr);
229 	else
230 		paddr = maddr & ~__IA64_UNCACHED_OFFSET;
231 
232 	pfn = paddr >> PAGE_SHIFT;
233 
234 	return pfn;
235 }
236 
237 static struct vm_operations_struct mspec_vm_ops = {
238 	.open = mspec_open,
239 	.close = mspec_close,
240 	.nopfn = mspec_nopfn
241 };
242 
243 /*
244  * mspec_mmap
245  *
246  * Called when mmaping the device.  Initializes the vma with a fault handler
247  * and private data structure necessary to allocate, track, and free the
248  * underlying pages.
249  */
250 static int
251 mspec_mmap(struct file *file, struct vm_area_struct *vma,
252 					enum mspec_page_type type)
253 {
254 	struct vma_data *vdata;
255 	int pages, vdata_size, flags = 0;
256 
257 	if (vma->vm_pgoff != 0)
258 		return -EINVAL;
259 
260 	if ((vma->vm_flags & VM_SHARED) == 0)
261 		return -EINVAL;
262 
263 	if ((vma->vm_flags & VM_WRITE) == 0)
264 		return -EPERM;
265 
266 	pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
267 	vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
268 	if (vdata_size <= PAGE_SIZE)
269 		vdata = kmalloc(vdata_size, GFP_KERNEL);
270 	else {
271 		vdata = vmalloc(vdata_size);
272 		flags = VMD_VMALLOCED;
273 	}
274 	if (!vdata)
275 		return -ENOMEM;
276 	memset(vdata, 0, vdata_size);
277 
278 	vdata->vm_start = vma->vm_start;
279 	vdata->vm_end = vma->vm_end;
280 	vdata->flags = flags;
281 	vdata->type = type;
282 	spin_lock_init(&vdata->lock);
283 	vdata->refcnt = ATOMIC_INIT(1);
284 	vma->vm_private_data = vdata;
285 
286 	vma->vm_flags |= (VM_IO | VM_RESERVED | VM_PFNMAP | VM_DONTEXPAND);
287 	if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
288 		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
289 	vma->vm_ops = &mspec_vm_ops;
290 
291 	return 0;
292 }
293 
294 static int
295 fetchop_mmap(struct file *file, struct vm_area_struct *vma)
296 {
297 	return mspec_mmap(file, vma, MSPEC_FETCHOP);
298 }
299 
300 static int
301 cached_mmap(struct file *file, struct vm_area_struct *vma)
302 {
303 	return mspec_mmap(file, vma, MSPEC_CACHED);
304 }
305 
306 static int
307 uncached_mmap(struct file *file, struct vm_area_struct *vma)
308 {
309 	return mspec_mmap(file, vma, MSPEC_UNCACHED);
310 }
311 
312 static const struct file_operations fetchop_fops = {
313 	.owner = THIS_MODULE,
314 	.mmap = fetchop_mmap
315 };
316 
317 static struct miscdevice fetchop_miscdev = {
318 	.minor = MISC_DYNAMIC_MINOR,
319 	.name = "sgi_fetchop",
320 	.fops = &fetchop_fops
321 };
322 
323 static const struct file_operations cached_fops = {
324 	.owner = THIS_MODULE,
325 	.mmap = cached_mmap
326 };
327 
328 static struct miscdevice cached_miscdev = {
329 	.minor = MISC_DYNAMIC_MINOR,
330 	.name = "mspec_cached",
331 	.fops = &cached_fops
332 };
333 
334 static const struct file_operations uncached_fops = {
335 	.owner = THIS_MODULE,
336 	.mmap = uncached_mmap
337 };
338 
339 static struct miscdevice uncached_miscdev = {
340 	.minor = MISC_DYNAMIC_MINOR,
341 	.name = "mspec_uncached",
342 	.fops = &uncached_fops
343 };
344 
345 /*
346  * mspec_init
347  *
348  * Called at boot time to initialize the mspec facility.
349  */
350 static int __init
351 mspec_init(void)
352 {
353 	int ret;
354 	int nid;
355 
356 	/*
357 	 * The fetchop device only works on SN2 hardware, uncached and cached
358 	 * memory drivers should both be valid on all ia64 hardware
359 	 */
360 #ifdef CONFIG_SGI_SN
361 	if (ia64_platform_is("sn2")) {
362 		is_sn2 = 1;
363 		if (is_shub2()) {
364 			ret = -ENOMEM;
365 			for_each_node_state(nid, N_ONLINE) {
366 				int actual_nid;
367 				int nasid;
368 				unsigned long phys;
369 
370 				scratch_page[nid] = uncached_alloc_page(nid, 1);
371 				if (scratch_page[nid] == 0)
372 					goto free_scratch_pages;
373 				phys = __pa(scratch_page[nid]);
374 				nasid = get_node_number(phys);
375 				actual_nid = nasid_to_cnodeid(nasid);
376 				if (actual_nid != nid)
377 					goto free_scratch_pages;
378 			}
379 		}
380 
381 		ret = misc_register(&fetchop_miscdev);
382 		if (ret) {
383 			printk(KERN_ERR
384 			       "%s: failed to register device %i\n",
385 			       FETCHOP_ID, ret);
386 			goto free_scratch_pages;
387 		}
388 	}
389 #endif
390 	ret = misc_register(&cached_miscdev);
391 	if (ret) {
392 		printk(KERN_ERR "%s: failed to register device %i\n",
393 		       CACHED_ID, ret);
394 		if (is_sn2)
395 			misc_deregister(&fetchop_miscdev);
396 		goto free_scratch_pages;
397 	}
398 	ret = misc_register(&uncached_miscdev);
399 	if (ret) {
400 		printk(KERN_ERR "%s: failed to register device %i\n",
401 		       UNCACHED_ID, ret);
402 		misc_deregister(&cached_miscdev);
403 		if (is_sn2)
404 			misc_deregister(&fetchop_miscdev);
405 		goto free_scratch_pages;
406 	}
407 
408 	printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
409 	       MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
410 	       CACHED_ID, UNCACHED_ID);
411 
412 	return 0;
413 
414  free_scratch_pages:
415 	for_each_node(nid) {
416 		if (scratch_page[nid] != 0)
417 			uncached_free_page(scratch_page[nid], 1);
418 	}
419 	return ret;
420 }
421 
422 static void __exit
423 mspec_exit(void)
424 {
425 	int nid;
426 
427 	misc_deregister(&uncached_miscdev);
428 	misc_deregister(&cached_miscdev);
429 	if (is_sn2) {
430 		misc_deregister(&fetchop_miscdev);
431 
432 		for_each_node(nid) {
433 			if (scratch_page[nid] != 0)
434 				uncached_free_page(scratch_page[nid], 1);
435 		}
436 	}
437 }
438 
439 module_init(mspec_init);
440 module_exit(mspec_exit);
441 
442 MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
443 MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
444 MODULE_LICENSE("GPL");
445