xref: /openbmc/linux/drivers/char/mspec.c (revision c21b37f6)
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 {
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  */
87 struct vma_data {
88 	atomic_t refcnt;	/* Number of vmas sharing the data. */
89 	spinlock_t lock;	/* Serialize access to the vma. */
90 	int count;		/* Number of pages allocated. */
91 	int type;		/* Type of pages allocated. */
92 	unsigned long maddr[0];	/* Array of MSPEC addresses. */
93 };
94 
95 /* used on shub2 to clear FOP cache in the HUB */
96 static unsigned long scratch_page[MAX_NUMNODES];
97 #define SH2_AMO_CACHE_ENTRIES	4
98 
99 static inline int
100 mspec_zero_block(unsigned long addr, int len)
101 {
102 	int status;
103 
104 	if (is_sn2) {
105 		if (is_shub2()) {
106 			int nid;
107 			void *p;
108 			int i;
109 
110 			nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
111 			p = (void *)TO_AMO(scratch_page[nid]);
112 
113 			for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
114 				FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
115 				p += FETCHOP_VAR_SIZE;
116 			}
117 		}
118 
119 		status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
120 				  BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
121 	} else {
122 		memset((char *) addr, 0, len);
123 		status = 0;
124 	}
125 	return status;
126 }
127 
128 /*
129  * mspec_open
130  *
131  * Called when a device mapping is created by a means other than mmap
132  * (via fork, etc.).  Increments the reference count on the underlying
133  * mspec data so it is not freed prematurely.
134  */
135 static void
136 mspec_open(struct vm_area_struct *vma)
137 {
138 	struct vma_data *vdata;
139 
140 	vdata = vma->vm_private_data;
141 	atomic_inc(&vdata->refcnt);
142 }
143 
144 /*
145  * mspec_close
146  *
147  * Called when unmapping a device mapping. Frees all mspec pages
148  * belonging to the vma.
149  */
150 static void
151 mspec_close(struct vm_area_struct *vma)
152 {
153 	struct vma_data *vdata;
154 	int i, pages, result, vdata_size;
155 
156 	vdata = vma->vm_private_data;
157 	if (!atomic_dec_and_test(&vdata->refcnt))
158 		return;
159 
160 	pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
161 	vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
162 	for (i = 0; i < pages; i++) {
163 		if (vdata->maddr[i] == 0)
164 			continue;
165 		/*
166 		 * Clear the page before sticking it back
167 		 * into the pool.
168 		 */
169 		result = mspec_zero_block(vdata->maddr[i], PAGE_SIZE);
170 		if (!result)
171 			uncached_free_page(vdata->maddr[i]);
172 		else
173 			printk(KERN_WARNING "mspec_close(): "
174 			       "failed to zero page %i\n",
175 			       result);
176 	}
177 
178 	if (vdata_size <= PAGE_SIZE)
179 		kfree(vdata);
180 	else
181 		vfree(vdata);
182 }
183 
184 
185 /*
186  * mspec_nopfn
187  *
188  * Creates a mspec page and maps it to user space.
189  */
190 static unsigned long
191 mspec_nopfn(struct vm_area_struct *vma, unsigned long address)
192 {
193 	unsigned long paddr, maddr;
194 	unsigned long pfn;
195 	int index;
196 	struct vma_data *vdata = vma->vm_private_data;
197 
198 	index = (address - vma->vm_start) >> PAGE_SHIFT;
199 	maddr = (volatile unsigned long) vdata->maddr[index];
200 	if (maddr == 0) {
201 		maddr = uncached_alloc_page(numa_node_id());
202 		if (maddr == 0)
203 			return NOPFN_OOM;
204 
205 		spin_lock(&vdata->lock);
206 		if (vdata->maddr[index] == 0) {
207 			vdata->count++;
208 			vdata->maddr[index] = maddr;
209 		} else {
210 			uncached_free_page(maddr);
211 			maddr = vdata->maddr[index];
212 		}
213 		spin_unlock(&vdata->lock);
214 	}
215 
216 	if (vdata->type == MSPEC_FETCHOP)
217 		paddr = TO_AMO(maddr);
218 	else
219 		paddr = maddr & ~__IA64_UNCACHED_OFFSET;
220 
221 	pfn = paddr >> PAGE_SHIFT;
222 
223 	return pfn;
224 }
225 
226 static struct vm_operations_struct mspec_vm_ops = {
227 	.open = mspec_open,
228 	.close = mspec_close,
229 	.nopfn = mspec_nopfn
230 };
231 
232 /*
233  * mspec_mmap
234  *
235  * Called when mmaping the device.  Initializes the vma with a fault handler
236  * and private data structure necessary to allocate, track, and free the
237  * underlying pages.
238  */
239 static int
240 mspec_mmap(struct file *file, struct vm_area_struct *vma, int type)
241 {
242 	struct vma_data *vdata;
243 	int pages, vdata_size;
244 
245 	if (vma->vm_pgoff != 0)
246 		return -EINVAL;
247 
248 	if ((vma->vm_flags & VM_SHARED) == 0)
249 		return -EINVAL;
250 
251 	if ((vma->vm_flags & VM_WRITE) == 0)
252 		return -EPERM;
253 
254 	pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
255 	vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
256 	if (vdata_size <= PAGE_SIZE)
257 		vdata = kmalloc(vdata_size, GFP_KERNEL);
258 	else
259 		vdata = vmalloc(vdata_size);
260 	if (!vdata)
261 		return -ENOMEM;
262 	memset(vdata, 0, vdata_size);
263 
264 	vdata->type = type;
265 	spin_lock_init(&vdata->lock);
266 	vdata->refcnt = ATOMIC_INIT(1);
267 	vma->vm_private_data = vdata;
268 
269 	vma->vm_flags |= (VM_IO | VM_RESERVED | VM_PFNMAP);
270 	if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
271 		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
272 	vma->vm_ops = &mspec_vm_ops;
273 
274 	return 0;
275 }
276 
277 static int
278 fetchop_mmap(struct file *file, struct vm_area_struct *vma)
279 {
280 	return mspec_mmap(file, vma, MSPEC_FETCHOP);
281 }
282 
283 static int
284 cached_mmap(struct file *file, struct vm_area_struct *vma)
285 {
286 	return mspec_mmap(file, vma, MSPEC_CACHED);
287 }
288 
289 static int
290 uncached_mmap(struct file *file, struct vm_area_struct *vma)
291 {
292 	return mspec_mmap(file, vma, MSPEC_UNCACHED);
293 }
294 
295 static const struct file_operations fetchop_fops = {
296 	.owner = THIS_MODULE,
297 	.mmap = fetchop_mmap
298 };
299 
300 static struct miscdevice fetchop_miscdev = {
301 	.minor = MISC_DYNAMIC_MINOR,
302 	.name = "sgi_fetchop",
303 	.fops = &fetchop_fops
304 };
305 
306 static const struct file_operations cached_fops = {
307 	.owner = THIS_MODULE,
308 	.mmap = cached_mmap
309 };
310 
311 static struct miscdevice cached_miscdev = {
312 	.minor = MISC_DYNAMIC_MINOR,
313 	.name = "mspec_cached",
314 	.fops = &cached_fops
315 };
316 
317 static const struct file_operations uncached_fops = {
318 	.owner = THIS_MODULE,
319 	.mmap = uncached_mmap
320 };
321 
322 static struct miscdevice uncached_miscdev = {
323 	.minor = MISC_DYNAMIC_MINOR,
324 	.name = "mspec_uncached",
325 	.fops = &uncached_fops
326 };
327 
328 /*
329  * mspec_init
330  *
331  * Called at boot time to initialize the mspec facility.
332  */
333 static int __init
334 mspec_init(void)
335 {
336 	int ret;
337 	int nid;
338 
339 	/*
340 	 * The fetchop device only works on SN2 hardware, uncached and cached
341 	 * memory drivers should both be valid on all ia64 hardware
342 	 */
343 #ifdef CONFIG_SGI_SN
344 	if (ia64_platform_is("sn2")) {
345 		is_sn2 = 1;
346 		if (is_shub2()) {
347 			ret = -ENOMEM;
348 			for_each_online_node(nid) {
349 				int actual_nid;
350 				int nasid;
351 				unsigned long phys;
352 
353 				scratch_page[nid] = uncached_alloc_page(nid);
354 				if (scratch_page[nid] == 0)
355 					goto free_scratch_pages;
356 				phys = __pa(scratch_page[nid]);
357 				nasid = get_node_number(phys);
358 				actual_nid = nasid_to_cnodeid(nasid);
359 				if (actual_nid != nid)
360 					goto free_scratch_pages;
361 			}
362 		}
363 
364 		ret = misc_register(&fetchop_miscdev);
365 		if (ret) {
366 			printk(KERN_ERR
367 			       "%s: failed to register device %i\n",
368 			       FETCHOP_ID, ret);
369 			goto free_scratch_pages;
370 		}
371 	}
372 #endif
373 	ret = misc_register(&cached_miscdev);
374 	if (ret) {
375 		printk(KERN_ERR "%s: failed to register device %i\n",
376 		       CACHED_ID, ret);
377 		if (is_sn2)
378 			misc_deregister(&fetchop_miscdev);
379 		goto free_scratch_pages;
380 	}
381 	ret = misc_register(&uncached_miscdev);
382 	if (ret) {
383 		printk(KERN_ERR "%s: failed to register device %i\n",
384 		       UNCACHED_ID, ret);
385 		misc_deregister(&cached_miscdev);
386 		if (is_sn2)
387 			misc_deregister(&fetchop_miscdev);
388 		goto free_scratch_pages;
389 	}
390 
391 	printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
392 	       MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
393 	       CACHED_ID, UNCACHED_ID);
394 
395 	return 0;
396 
397  free_scratch_pages:
398 	for_each_node(nid) {
399 		if (scratch_page[nid] != 0)
400 			uncached_free_page(scratch_page[nid]);
401 	}
402 	return ret;
403 }
404 
405 static void __exit
406 mspec_exit(void)
407 {
408 	int nid;
409 
410 	misc_deregister(&uncached_miscdev);
411 	misc_deregister(&cached_miscdev);
412 	if (is_sn2) {
413 		misc_deregister(&fetchop_miscdev);
414 
415 		for_each_node(nid) {
416 			if (scratch_page[nid] != 0)
417 				uncached_free_page(scratch_page[nid]);
418 		}
419 	}
420 }
421 
422 module_init(mspec_init);
423 module_exit(mspec_exit);
424 
425 MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
426 MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
427 MODULE_LICENSE("GPL");
428