1/*
2 * Copyright (C) 2012 Google, Inc.
3 *
4 * This software is licensed under the terms of the GNU General Public
5 * License version 2, as published by the Free Software Foundation, and
6 * may be copied, distributed, and modified under those terms.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11 * GNU General Public License for more details.
12 *
13 */
14
15#include <linux/device.h>
16#include <linux/err.h>
17#include <linux/errno.h>
18#include <linux/kernel.h>
19#include <linux/init.h>
20#include <linux/io.h>
21#include <linux/list.h>
22#include <linux/memblock.h>
23#include <linux/persistent_ram.h>
24#include <linux/rslib.h>
25#include <linux/slab.h>
26#include <linux/vmalloc.h>
27
28struct persistent_ram_buffer {
29	uint32_t    sig;
30	atomic_t    start;
31	atomic_t    size;
32	uint8_t     data[0];
33};
34
35#define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
36
37static __devinitdata LIST_HEAD(persistent_ram_list);
38
39static inline size_t buffer_size(struct persistent_ram_zone *prz)
40{
41	return atomic_read(&prz->buffer->size);
42}
43
44static inline size_t buffer_start(struct persistent_ram_zone *prz)
45{
46	return atomic_read(&prz->buffer->start);
47}
48
49/* increase and wrap the start pointer, returning the old value */
50static inline size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
51{
52	int old;
53	int new;
54
55	do {
56		old = atomic_read(&prz->buffer->start);
57		new = old + a;
58		while (unlikely(new > prz->buffer_size))
59			new -= prz->buffer_size;
60	} while (atomic_cmpxchg(&prz->buffer->start, old, new) != old);
61
62	return old;
63}
64
65/* increase the size counter until it hits the max size */
66static inline void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
67{
68	size_t old;
69	size_t new;
70
71	if (atomic_read(&prz->buffer->size) == prz->buffer_size)
72		return;
73
74	do {
75		old = atomic_read(&prz->buffer->size);
76		new = old + a;
77		if (new > prz->buffer_size)
78			new = prz->buffer_size;
79	} while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
80}
81
82static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
83	uint8_t *data, size_t len, uint8_t *ecc)
84{
85	int i;
86	uint16_t par[prz->ecc_size];
87
88	/* Initialize the parity buffer */
89	memset(par, 0, sizeof(par));
90	encode_rs8(prz->rs_decoder, data, len, par, 0);
91	for (i = 0; i < prz->ecc_size; i++)
92		ecc[i] = par[i];
93}
94
95static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
96	void *data, size_t len, uint8_t *ecc)
97{
98	int i;
99	uint16_t par[prz->ecc_size];
100
101	for (i = 0; i < prz->ecc_size; i++)
102		par[i] = ecc[i];
103	return decode_rs8(prz->rs_decoder, data, par, len,
104				NULL, 0, NULL, 0, NULL);
105}
106
107static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
108	unsigned int start, unsigned int count)
109{
110	struct persistent_ram_buffer *buffer = prz->buffer;
111	uint8_t *buffer_end = buffer->data + prz->buffer_size;
112	uint8_t *block;
113	uint8_t *par;
114	int ecc_block_size = prz->ecc_block_size;
115	int ecc_size = prz->ecc_size;
116	int size = prz->ecc_block_size;
117
118	if (!prz->ecc)
119		return;
120
121	block = buffer->data + (start & ~(ecc_block_size - 1));
122	par = prz->par_buffer + (start / ecc_block_size) * prz->ecc_size;
123
124	do {
125		if (block + ecc_block_size > buffer_end)
126			size = buffer_end - block;
127		persistent_ram_encode_rs8(prz, block, size, par);
128		block += ecc_block_size;
129		par += ecc_size;
130	} while (block < buffer->data + start + count);
131}
132
133static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
134{
135	struct persistent_ram_buffer *buffer = prz->buffer;
136
137	if (!prz->ecc)
138		return;
139
140	persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
141				  prz->par_header);
142}
143
144static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
145{
146	struct persistent_ram_buffer *buffer = prz->buffer;
147	uint8_t *block;
148	uint8_t *par;
149
150	if (!prz->ecc)
151		return;
152
153	block = buffer->data;
154	par = prz->par_buffer;
155	while (block < buffer->data + buffer_size(prz)) {
156		int numerr;
157		int size = prz->ecc_block_size;
158		if (block + size > buffer->data + prz->buffer_size)
159			size = buffer->data + prz->buffer_size - block;
160		numerr = persistent_ram_decode_rs8(prz, block, size, par);
161		if (numerr > 0) {
162			pr_devel("persistent_ram: error in block %p, %d\n",
163			       block, numerr);
164			prz->corrected_bytes += numerr;
165		} else if (numerr < 0) {
166			pr_devel("persistent_ram: uncorrectable error in block %p\n",
167				block);
168			prz->bad_blocks++;
169		}
170		block += prz->ecc_block_size;
171		par += prz->ecc_size;
172	}
173}
174
175static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
176	size_t buffer_size, struct persistent_ram *ram)
177{
178	int numerr;
179	struct persistent_ram_buffer *buffer = prz->buffer;
180	int ecc_blocks;
181
182	if (!prz->ecc)
183		return 0;
184
185	prz->ecc_block_size = ram->ecc_block_size ?: 128;
186	prz->ecc_size = ram->ecc_size ?: 16;
187	prz->ecc_symsize = ram->ecc_symsize ?: 8;
188	prz->ecc_poly = ram->ecc_poly ?: 0x11d;
189
190	ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_size,
191				  prz->ecc_block_size + prz->ecc_size);
192	prz->buffer_size -= (ecc_blocks + 1) * prz->ecc_size;
193
194	if (prz->buffer_size > buffer_size) {
195		pr_err("persistent_ram: invalid size %zu, non-ecc datasize %zu\n",
196		       buffer_size, prz->buffer_size);
197		return -EINVAL;
198	}
199
200	prz->par_buffer = buffer->data + prz->buffer_size;
201	prz->par_header = prz->par_buffer + ecc_blocks * prz->ecc_size;
202
203	/*
204	 * first consecutive root is 0
205	 * primitive element to generate roots = 1
206	 */
207	prz->rs_decoder = init_rs(prz->ecc_symsize, prz->ecc_poly, 0, 1,
208				  prz->ecc_size);
209	if (prz->rs_decoder == NULL) {
210		pr_info("persistent_ram: init_rs failed\n");
211		return -EINVAL;
212	}
213
214	prz->corrected_bytes = 0;
215	prz->bad_blocks = 0;
216
217	numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
218					   prz->par_header);
219	if (numerr > 0) {
220		pr_info("persistent_ram: error in header, %d\n", numerr);
221		prz->corrected_bytes += numerr;
222	} else if (numerr < 0) {
223		pr_info("persistent_ram: uncorrectable error in header\n");
224		prz->bad_blocks++;
225	}
226
227	return 0;
228}
229
230ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
231	char *str, size_t len)
232{
233	ssize_t ret;
234
235	if (prz->corrected_bytes || prz->bad_blocks)
236		ret = snprintf(str, len, ""
237			"\n%d Corrected bytes, %d unrecoverable blocks\n",
238			prz->corrected_bytes, prz->bad_blocks);
239	else
240		ret = snprintf(str, len, "\nNo errors detected\n");
241
242	return ret;
243}
244
245static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
246	const void *s, unsigned int start, unsigned int count)
247{
248	struct persistent_ram_buffer *buffer = prz->buffer;
249	memcpy(buffer->data + start, s, count);
250	persistent_ram_update_ecc(prz, start, count);
251}
252
253static void __devinit
254persistent_ram_save_old(struct persistent_ram_zone *prz)
255{
256	struct persistent_ram_buffer *buffer = prz->buffer;
257	size_t size = buffer_size(prz);
258	size_t start = buffer_start(prz);
259	char *dest;
260
261	persistent_ram_ecc_old(prz);
262
263	dest = kmalloc(size, GFP_KERNEL);
264	if (dest == NULL) {
265		pr_err("persistent_ram: failed to allocate buffer\n");
266		return;
267	}
268
269	prz->old_log = dest;
270	prz->old_log_size = size;
271	memcpy(prz->old_log, &buffer->data[start], size - start);
272	memcpy(prz->old_log + size - start, &buffer->data[0], start);
273}
274
275int notrace persistent_ram_write(struct persistent_ram_zone *prz,
276	const void *s, unsigned int count)
277{
278	int rem;
279	int c = count;
280	size_t start;
281
282	if (unlikely(c > prz->buffer_size)) {
283		s += c - prz->buffer_size;
284		c = prz->buffer_size;
285	}
286
287	buffer_size_add(prz, c);
288
289	start = buffer_start_add(prz, c);
290
291	rem = prz->buffer_size - start;
292	if (unlikely(rem < c)) {
293		persistent_ram_update(prz, s, start, rem);
294		s += rem;
295		c -= rem;
296		start = 0;
297	}
298	persistent_ram_update(prz, s, start, c);
299
300	persistent_ram_update_header_ecc(prz);
301
302	return count;
303}
304
305size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
306{
307	return prz->old_log_size;
308}
309
310void *persistent_ram_old(struct persistent_ram_zone *prz)
311{
312	return prz->old_log;
313}
314
315void persistent_ram_free_old(struct persistent_ram_zone *prz)
316{
317	kfree(prz->old_log);
318	prz->old_log = NULL;
319	prz->old_log_size = 0;
320}
321
322static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
323		struct persistent_ram_zone *prz)
324{
325	struct page **pages;
326	phys_addr_t page_start;
327	unsigned int page_count;
328	pgprot_t prot;
329	unsigned int i;
330
331	page_start = start - offset_in_page(start);
332	page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
333
334	prot = pgprot_noncached(PAGE_KERNEL);
335
336	pages = kmalloc(sizeof(struct page *) * page_count, GFP_KERNEL);
337	if (!pages) {
338		pr_err("%s: Failed to allocate array for %u pages\n", __func__,
339			page_count);
340		return -ENOMEM;
341	}
342
343	for (i = 0; i < page_count; i++) {
344		phys_addr_t addr = page_start + i * PAGE_SIZE;
345		pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
346	}
347	prz->vaddr = vmap(pages, page_count, VM_MAP, prot);
348	kfree(pages);
349	if (!prz->vaddr) {
350		pr_err("%s: Failed to map %u pages\n", __func__, page_count);
351		return -ENOMEM;
352	}
353
354	prz->buffer = prz->vaddr + offset_in_page(start);
355	prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
356
357	return 0;
358}
359
360static int __devinit persistent_ram_buffer_init(const char *name,
361		struct persistent_ram_zone *prz, struct persistent_ram **ramp)
362{
363	int i;
364	struct persistent_ram *ram;
365	struct persistent_ram_descriptor *desc;
366	phys_addr_t start;
367
368	list_for_each_entry(ram, &persistent_ram_list, node) {
369		start = ram->start;
370		for (i = 0; i < ram->num_descs; i++) {
371			desc = &ram->descs[i];
372			if (!strcmp(desc->name, name)) {
373				*ramp = ram;
374				return persistent_ram_buffer_map(start,
375						desc->size, prz);
376			}
377			start += desc->size;
378		}
379	}
380
381	return -EINVAL;
382}
383
384static  __devinit
385struct persistent_ram_zone *__persistent_ram_init(struct device *dev, bool ecc)
386{
387	struct persistent_ram *ram;
388	struct persistent_ram_zone *prz;
389	int ret = -ENOMEM;
390
391	prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
392	if (!prz) {
393		pr_err("persistent_ram: failed to allocate persistent ram zone\n");
394		goto err;
395	}
396
397	INIT_LIST_HEAD(&prz->node);
398
399	ret = persistent_ram_buffer_init(dev_name(dev), prz, &ram);
400	if (ret) {
401		pr_err("persistent_ram: failed to initialize buffer\n");
402		goto err;
403	}
404
405	prz->ecc = ecc;
406	ret = persistent_ram_init_ecc(prz, prz->buffer_size, ram);
407	if (ret)
408		goto err;
409
410	if (prz->buffer->sig == PERSISTENT_RAM_SIG) {
411		if (buffer_size(prz) > prz->buffer_size ||
412		    buffer_start(prz) > buffer_size(prz))
413			pr_info("persistent_ram: found existing invalid buffer,"
414				" size %zu, start %zu\n",
415			       buffer_size(prz), buffer_start(prz));
416		else {
417			pr_info("persistent_ram: found existing buffer,"
418				" size %zu, start %zu\n",
419			       buffer_size(prz), buffer_start(prz));
420			persistent_ram_save_old(prz);
421		}
422	} else {
423		pr_info("persistent_ram: no valid data in buffer"
424			" (sig = 0x%08x)\n", prz->buffer->sig);
425	}
426
427	prz->buffer->sig = PERSISTENT_RAM_SIG;
428	atomic_set(&prz->buffer->start, 0);
429	atomic_set(&prz->buffer->size, 0);
430
431	return prz;
432err:
433	kfree(prz);
434	return ERR_PTR(ret);
435}
436
437struct persistent_ram_zone * __devinit
438persistent_ram_init_ringbuffer(struct device *dev, bool ecc)
439{
440	return __persistent_ram_init(dev, ecc);
441}
442
443int __init persistent_ram_early_init(struct persistent_ram *ram)
444{
445	int ret;
446
447	ret = memblock_reserve(ram->start, ram->size);
448	if (ret) {
449		pr_err("Failed to reserve persistent memory from %08lx-%08lx\n",
450			(long)ram->start, (long)(ram->start + ram->size - 1));
451		return ret;
452	}
453
454	list_add_tail(&ram->node, &persistent_ram_list);
455
456	pr_info("Initialized persistent memory from %08lx-%08lx\n",
457		(long)ram->start, (long)(ram->start + ram->size - 1));
458
459	return 0;
460}
461