xref: /openbmc/linux/drivers/char/mspec.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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/vmalloc.h>
42 #include <linux/string.h>
43 #include <linux/slab.h>
44 #include <linux/numa.h>
45 #include <asm/page.h>
46 #include <asm/system.h>
47 #include <asm/pgtable.h>
48 #include <asm/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  */
69 enum {
70 	MSPEC_FETCHOP = 1,
71 	MSPEC_CACHED,
72 	MSPEC_UNCACHED
73 };
74 
75 #ifdef CONFIG_SGI_SN
76 static 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  */
86 struct vma_data {
87 	atomic_t refcnt;	/* Number of vmas sharing the data. */
88 	spinlock_t lock;	/* Serialize access to the vma. */
89 	int count;		/* Number of pages allocated. */
90 	int type;		/* Type of pages allocated. */
91 	unsigned long maddr[0];	/* Array of MSPEC addresses. */
92 };
93 
94 /* used on shub2 to clear FOP cache in the HUB */
95 static unsigned long scratch_page[MAX_NUMNODES];
96 #define SH2_AMO_CACHE_ENTRIES	4
97 
98 static inline int
99 mspec_zero_block(unsigned long addr, int len)
100 {
101 	int status;
102 
103 	if (is_sn2) {
104 		if (is_shub2()) {
105 			int nid;
106 			void *p;
107 			int i;
108 
109 			nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
110 			p = (void *)TO_AMO(scratch_page[nid]);
111 
112 			for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
113 				FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
114 				p += FETCHOP_VAR_SIZE;
115 			}
116 		}
117 
118 		status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
119 				  BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
120 	} else {
121 		memset((char *) addr, 0, len);
122 		status = 0;
123 	}
124 	return status;
125 }
126 
127 /*
128  * mspec_open
129  *
130  * Called when a device mapping is created by a means other than mmap
131  * (via fork, etc.).  Increments the reference count on the underlying
132  * mspec data so it is not freed prematurely.
133  */
134 static void
135 mspec_open(struct vm_area_struct *vma)
136 {
137 	struct vma_data *vdata;
138 
139 	vdata = vma->vm_private_data;
140 	atomic_inc(&vdata->refcnt);
141 }
142 
143 /*
144  * mspec_close
145  *
146  * Called when unmapping a device mapping. Frees all mspec pages
147  * belonging to the vma.
148  */
149 static void
150 mspec_close(struct vm_area_struct *vma)
151 {
152 	struct vma_data *vdata;
153 	int i, pages, result, vdata_size;
154 
155 	vdata = vma->vm_private_data;
156 	if (!atomic_dec_and_test(&vdata->refcnt))
157 		return;
158 
159 	pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
160 	vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
161 	for (i = 0; i < pages; i++) {
162 		if (vdata->maddr[i] == 0)
163 			continue;
164 		/*
165 		 * Clear the page before sticking it back
166 		 * into the pool.
167 		 */
168 		result = mspec_zero_block(vdata->maddr[i], PAGE_SIZE);
169 		if (!result)
170 			uncached_free_page(vdata->maddr[i]);
171 		else
172 			printk(KERN_WARNING "mspec_close(): "
173 			       "failed to zero page %i\n",
174 			       result);
175 	}
176 
177 	if (vdata_size <= PAGE_SIZE)
178 		kfree(vdata);
179 	else
180 		vfree(vdata);
181 }
182 
183 
184 /*
185  * mspec_nopfn
186  *
187  * Creates a mspec page and maps it to user space.
188  */
189 static unsigned long
190 mspec_nopfn(struct vm_area_struct *vma, unsigned long address)
191 {
192 	unsigned long paddr, maddr;
193 	unsigned long pfn;
194 	int index;
195 	struct vma_data *vdata = vma->vm_private_data;
196 
197 	index = (address - vma->vm_start) >> PAGE_SHIFT;
198 	maddr = (volatile unsigned long) vdata->maddr[index];
199 	if (maddr == 0) {
200 		maddr = uncached_alloc_page(numa_node_id());
201 		if (maddr == 0)
202 			return NOPFN_OOM;
203 
204 		spin_lock(&vdata->lock);
205 		if (vdata->maddr[index] == 0) {
206 			vdata->count++;
207 			vdata->maddr[index] = maddr;
208 		} else {
209 			uncached_free_page(maddr);
210 			maddr = vdata->maddr[index];
211 		}
212 		spin_unlock(&vdata->lock);
213 	}
214 
215 	if (vdata->type == MSPEC_FETCHOP)
216 		paddr = TO_AMO(maddr);
217 	else
218 		paddr = maddr & ~__IA64_UNCACHED_OFFSET;
219 
220 	pfn = paddr >> PAGE_SHIFT;
221 
222 	return pfn;
223 }
224 
225 static struct vm_operations_struct mspec_vm_ops = {
226 	.open = mspec_open,
227 	.close = mspec_close,
228 	.nopfn = mspec_nopfn
229 };
230 
231 /*
232  * mspec_mmap
233  *
234  * Called when mmaping the device.  Initializes the vma with a fault handler
235  * and private data structure necessary to allocate, track, and free the
236  * underlying pages.
237  */
238 static int
239 mspec_mmap(struct file *file, struct vm_area_struct *vma, int type)
240 {
241 	struct vma_data *vdata;
242 	int pages, vdata_size;
243 
244 	if (vma->vm_pgoff != 0)
245 		return -EINVAL;
246 
247 	if ((vma->vm_flags & VM_SHARED) == 0)
248 		return -EINVAL;
249 
250 	if ((vma->vm_flags & VM_WRITE) == 0)
251 		return -EPERM;
252 
253 	pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
254 	vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
255 	if (vdata_size <= PAGE_SIZE)
256 		vdata = kmalloc(vdata_size, GFP_KERNEL);
257 	else
258 		vdata = vmalloc(vdata_size);
259 	if (!vdata)
260 		return -ENOMEM;
261 	memset(vdata, 0, vdata_size);
262 
263 	vdata->type = type;
264 	spin_lock_init(&vdata->lock);
265 	vdata->refcnt = ATOMIC_INIT(1);
266 	vma->vm_private_data = vdata;
267 
268 	vma->vm_flags |= (VM_IO | VM_LOCKED | VM_RESERVED | VM_PFNMAP);
269 	if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
270 		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
271 	vma->vm_ops = &mspec_vm_ops;
272 
273 	return 0;
274 }
275 
276 static int
277 fetchop_mmap(struct file *file, struct vm_area_struct *vma)
278 {
279 	return mspec_mmap(file, vma, MSPEC_FETCHOP);
280 }
281 
282 static int
283 cached_mmap(struct file *file, struct vm_area_struct *vma)
284 {
285 	return mspec_mmap(file, vma, MSPEC_CACHED);
286 }
287 
288 static int
289 uncached_mmap(struct file *file, struct vm_area_struct *vma)
290 {
291 	return mspec_mmap(file, vma, MSPEC_UNCACHED);
292 }
293 
294 static const struct file_operations fetchop_fops = {
295 	.owner = THIS_MODULE,
296 	.mmap = fetchop_mmap
297 };
298 
299 static struct miscdevice fetchop_miscdev = {
300 	.minor = MISC_DYNAMIC_MINOR,
301 	.name = "sgi_fetchop",
302 	.fops = &fetchop_fops
303 };
304 
305 static const struct file_operations cached_fops = {
306 	.owner = THIS_MODULE,
307 	.mmap = cached_mmap
308 };
309 
310 static struct miscdevice cached_miscdev = {
311 	.minor = MISC_DYNAMIC_MINOR,
312 	.name = "mspec_cached",
313 	.fops = &cached_fops
314 };
315 
316 static const struct file_operations uncached_fops = {
317 	.owner = THIS_MODULE,
318 	.mmap = uncached_mmap
319 };
320 
321 static struct miscdevice uncached_miscdev = {
322 	.minor = MISC_DYNAMIC_MINOR,
323 	.name = "mspec_uncached",
324 	.fops = &uncached_fops
325 };
326 
327 /*
328  * mspec_init
329  *
330  * Called at boot time to initialize the mspec facility.
331  */
332 static int __init
333 mspec_init(void)
334 {
335 	int ret;
336 	int nid;
337 
338 	/*
339 	 * The fetchop device only works on SN2 hardware, uncached and cached
340 	 * memory drivers should both be valid on all ia64 hardware
341 	 */
342 #ifdef CONFIG_SGI_SN
343 	if (ia64_platform_is("sn2")) {
344 		is_sn2 = 1;
345 		if (is_shub2()) {
346 			ret = -ENOMEM;
347 			for_each_online_node(nid) {
348 				int actual_nid;
349 				int nasid;
350 				unsigned long phys;
351 
352 				scratch_page[nid] = uncached_alloc_page(nid);
353 				if (scratch_page[nid] == 0)
354 					goto free_scratch_pages;
355 				phys = __pa(scratch_page[nid]);
356 				nasid = get_node_number(phys);
357 				actual_nid = nasid_to_cnodeid(nasid);
358 				if (actual_nid != nid)
359 					goto free_scratch_pages;
360 			}
361 		}
362 
363 		ret = misc_register(&fetchop_miscdev);
364 		if (ret) {
365 			printk(KERN_ERR
366 			       "%s: failed to register device %i\n",
367 			       FETCHOP_ID, ret);
368 			goto free_scratch_pages;
369 		}
370 	}
371 #endif
372 	ret = misc_register(&cached_miscdev);
373 	if (ret) {
374 		printk(KERN_ERR "%s: failed to register device %i\n",
375 		       CACHED_ID, ret);
376 		if (is_sn2)
377 			misc_deregister(&fetchop_miscdev);
378 		goto free_scratch_pages;
379 	}
380 	ret = misc_register(&uncached_miscdev);
381 	if (ret) {
382 		printk(KERN_ERR "%s: failed to register device %i\n",
383 		       UNCACHED_ID, ret);
384 		misc_deregister(&cached_miscdev);
385 		if (is_sn2)
386 			misc_deregister(&fetchop_miscdev);
387 		goto free_scratch_pages;
388 	}
389 
390 	printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
391 	       MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
392 	       CACHED_ID, UNCACHED_ID);
393 
394 	return 0;
395 
396  free_scratch_pages:
397 	for_each_node(nid) {
398 		if (scratch_page[nid] != 0)
399 			uncached_free_page(scratch_page[nid]);
400 	}
401 	return ret;
402 }
403 
404 static void __exit
405 mspec_exit(void)
406 {
407 	int nid;
408 
409 	misc_deregister(&uncached_miscdev);
410 	misc_deregister(&cached_miscdev);
411 	if (is_sn2) {
412 		misc_deregister(&fetchop_miscdev);
413 
414 		for_each_node(nid) {
415 			if (scratch_page[nid] != 0)
416 				uncached_free_page(scratch_page[nid]);
417 		}
418 	}
419 }
420 
421 module_init(mspec_init);
422 module_exit(mspec_exit);
423 
424 MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
425 MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
426 MODULE_LICENSE("GPL");
427