2 * Copyright (C) 2012 Google, Inc.
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.
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.
15 #define pr_fmt(fmt) "persistent_ram: " fmt
17 #include <linux/device.h>
18 #include <linux/err.h>
19 #include <linux/errno.h>
20 #include <linux/kernel.h>
21 #include <linux/init.h>
23 #include <linux/list.h>
24 #include <linux/memblock.h>
25 #include <linux/rslib.h>
26 #include <linux/slab.h>
27 #include <linux/vmalloc.h>
28 #include <linux/pstore_ram.h>
31 struct persistent_ram_buffer {
38 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
40 static inline size_t buffer_size(struct persistent_ram_zone *prz)
42 return atomic_read(&prz->buffer->size);
45 static inline size_t buffer_start(struct persistent_ram_zone *prz)
47 return atomic_read(&prz->buffer->start);
50 /* increase and wrap the start pointer, returning the old value */
51 static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
55 unsigned long flags = 0;
57 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
58 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
60 old = atomic_read(&prz->buffer->start);
62 while (unlikely(new >= prz->buffer_size))
63 new -= prz->buffer_size;
64 atomic_set(&prz->buffer->start, new);
66 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
67 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
72 /* increase the size counter until it hits the max size */
73 static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
77 unsigned long flags = 0;
79 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
80 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
82 old = atomic_read(&prz->buffer->size);
83 if (old == prz->buffer_size)
87 if (new > prz->buffer_size)
88 new = prz->buffer_size;
89 atomic_set(&prz->buffer->size, new);
92 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
93 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
96 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
97 uint8_t *data, size_t len, uint8_t *ecc)
100 uint16_t par[prz->ecc_info.ecc_size];
102 /* Initialize the parity buffer */
103 memset(par, 0, sizeof(par));
104 encode_rs8(prz->rs_decoder, data, len, par, 0);
105 for (i = 0; i < prz->ecc_info.ecc_size; i++)
109 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
110 void *data, size_t len, uint8_t *ecc)
113 uint16_t par[prz->ecc_info.ecc_size];
115 for (i = 0; i < prz->ecc_info.ecc_size; i++)
117 return decode_rs8(prz->rs_decoder, data, par, len,
118 NULL, 0, NULL, 0, NULL);
121 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
122 unsigned int start, unsigned int count)
124 struct persistent_ram_buffer *buffer = prz->buffer;
125 uint8_t *buffer_end = buffer->data + prz->buffer_size;
128 int ecc_block_size = prz->ecc_info.block_size;
129 int ecc_size = prz->ecc_info.ecc_size;
130 int size = ecc_block_size;
135 block = buffer->data + (start & ~(ecc_block_size - 1));
136 par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
139 if (block + ecc_block_size > buffer_end)
140 size = buffer_end - block;
141 persistent_ram_encode_rs8(prz, block, size, par);
142 block += ecc_block_size;
144 } while (block < buffer->data + start + count);
147 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
149 struct persistent_ram_buffer *buffer = prz->buffer;
151 if (!prz->ecc_info.ecc_size)
154 persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
158 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
160 struct persistent_ram_buffer *buffer = prz->buffer;
164 if (!prz->ecc_info.ecc_size)
167 block = buffer->data;
168 par = prz->par_buffer;
169 while (block < buffer->data + buffer_size(prz)) {
171 int size = prz->ecc_info.block_size;
172 if (block + size > buffer->data + prz->buffer_size)
173 size = buffer->data + prz->buffer_size - block;
174 numerr = persistent_ram_decode_rs8(prz, block, size, par);
176 pr_devel("error in block %p, %d\n", block, numerr);
177 prz->corrected_bytes += numerr;
178 } else if (numerr < 0) {
179 pr_devel("uncorrectable error in block %p\n", block);
182 block += prz->ecc_info.block_size;
183 par += prz->ecc_info.ecc_size;
187 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
188 struct persistent_ram_ecc_info *ecc_info)
191 struct persistent_ram_buffer *buffer = prz->buffer;
195 if (!ecc_info || !ecc_info->ecc_size)
198 prz->ecc_info.block_size = ecc_info->block_size ?: 128;
199 prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
200 prz->ecc_info.symsize = ecc_info->symsize ?: 8;
201 prz->ecc_info.poly = ecc_info->poly ?: 0x11d;
203 ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
204 prz->ecc_info.block_size +
205 prz->ecc_info.ecc_size);
206 ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
207 if (ecc_total >= prz->buffer_size) {
208 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
209 __func__, prz->ecc_info.ecc_size,
210 ecc_total, prz->buffer_size);
214 prz->buffer_size -= ecc_total;
215 prz->par_buffer = buffer->data + prz->buffer_size;
216 prz->par_header = prz->par_buffer +
217 ecc_blocks * prz->ecc_info.ecc_size;
220 * first consecutive root is 0
221 * primitive element to generate roots = 1
223 prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
224 0, 1, prz->ecc_info.ecc_size);
225 if (prz->rs_decoder == NULL) {
226 pr_info("init_rs failed\n");
230 prz->corrected_bytes = 0;
233 numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
236 pr_info("error in header, %d\n", numerr);
237 prz->corrected_bytes += numerr;
238 } else if (numerr < 0) {
239 pr_info("uncorrectable error in header\n");
246 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
247 char *str, size_t len)
251 if (!prz->ecc_info.ecc_size)
254 if (prz->corrected_bytes || prz->bad_blocks)
255 ret = snprintf(str, len, ""
256 "\n%d Corrected bytes, %d unrecoverable blocks\n",
257 prz->corrected_bytes, prz->bad_blocks);
259 ret = snprintf(str, len, "\nNo errors detected\n");
264 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
265 const void *s, unsigned int start, unsigned int count)
267 struct persistent_ram_buffer *buffer = prz->buffer;
268 memcpy_toio(buffer->data + start, s, count);
269 persistent_ram_update_ecc(prz, start, count);
272 void persistent_ram_save_old(struct persistent_ram_zone *prz)
274 struct persistent_ram_buffer *buffer = prz->buffer;
275 size_t size = buffer_size(prz);
276 size_t start = buffer_start(prz);
282 persistent_ram_ecc_old(prz);
283 prz->old_log = kmalloc(size, GFP_KERNEL);
286 pr_err("failed to allocate buffer\n");
290 prz->old_log_size = size;
291 memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
292 memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
295 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
296 const void *s, unsigned int count)
302 if (unlikely(c > prz->buffer_size)) {
303 s += c - prz->buffer_size;
304 c = prz->buffer_size;
307 buffer_size_add(prz, c);
309 start = buffer_start_add(prz, c);
311 rem = prz->buffer_size - start;
312 if (unlikely(rem < c)) {
313 persistent_ram_update(prz, s, start, rem);
318 persistent_ram_update(prz, s, start, c);
320 persistent_ram_update_header_ecc(prz);
325 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
327 return prz->old_log_size;
330 void *persistent_ram_old(struct persistent_ram_zone *prz)
335 void persistent_ram_free_old(struct persistent_ram_zone *prz)
339 prz->old_log_size = 0;
342 void persistent_ram_zap(struct persistent_ram_zone *prz)
344 atomic_set(&prz->buffer->start, 0);
345 atomic_set(&prz->buffer->size, 0);
346 persistent_ram_update_header_ecc(prz);
349 static void *persistent_ram_vmap(phys_addr_t start, size_t size,
350 unsigned int memtype)
353 phys_addr_t page_start;
354 unsigned int page_count;
359 page_start = start - offset_in_page(start);
360 page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
363 prot = pgprot_noncached(PAGE_KERNEL);
365 prot = pgprot_writecombine(PAGE_KERNEL);
367 pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
369 pr_err("%s: Failed to allocate array for %u pages\n",
370 __func__, page_count);
374 for (i = 0; i < page_count; i++) {
375 phys_addr_t addr = page_start + i * PAGE_SIZE;
376 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
378 vaddr = vmap(pages, page_count, VM_MAP, prot);
382 * Since vmap() uses page granularity, we must add the offset
383 * into the page here, to get the byte granularity address
384 * into the mapping to represent the actual "start" location.
386 return vaddr + offset_in_page(start);
389 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
390 unsigned int memtype)
394 if (!request_mem_region(start, size, "persistent_ram")) {
395 pr_err("request mem region (0x%llx@0x%llx) failed\n",
396 (unsigned long long)size, (unsigned long long)start);
401 va = ioremap(start, size);
403 va = ioremap_wc(start, size);
406 * Since request_mem_region() and ioremap() are byte-granularity
407 * there is no need handle anything special like we do when the
408 * vmap() case in persistent_ram_vmap() above.
413 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
414 struct persistent_ram_zone *prz, int memtype)
419 if (pfn_valid(start >> PAGE_SHIFT))
420 prz->vaddr = persistent_ram_vmap(start, size, memtype);
422 prz->vaddr = persistent_ram_iomap(start, size, memtype);
425 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
426 (unsigned long long)size, (unsigned long long)start);
430 prz->buffer = prz->vaddr;
431 prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
436 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
437 struct persistent_ram_ecc_info *ecc_info)
441 ret = persistent_ram_init_ecc(prz, ecc_info);
445 sig ^= PERSISTENT_RAM_SIG;
447 if (prz->buffer->sig == sig) {
448 if (buffer_size(prz) == 0) {
449 pr_debug("found existing empty buffer\n");
453 if (buffer_size(prz) > prz->buffer_size ||
454 buffer_start(prz) > buffer_size(prz))
455 pr_info("found existing invalid buffer, size %zu, start %zu\n",
456 buffer_size(prz), buffer_start(prz));
458 pr_debug("found existing buffer, size %zu, start %zu\n",
459 buffer_size(prz), buffer_start(prz));
460 persistent_ram_save_old(prz);
464 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
468 /* Rewind missing or invalid memory area. */
469 prz->buffer->sig = sig;
470 persistent_ram_zap(prz);
475 void persistent_ram_free(struct persistent_ram_zone *prz)
481 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
482 /* We must vunmap() at page-granularity. */
483 vunmap(prz->vaddr - offset_in_page(prz->paddr));
486 release_mem_region(prz->paddr, prz->size);
490 persistent_ram_free_old(prz);
494 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
495 u32 sig, struct persistent_ram_ecc_info *ecc_info,
496 unsigned int memtype, u32 flags)
498 struct persistent_ram_zone *prz;
501 prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
503 pr_err("failed to allocate persistent ram zone\n");
507 /* Initialize general buffer state. */
508 raw_spin_lock_init(&prz->buffer_lock);
511 ret = persistent_ram_buffer_map(start, size, prz, memtype);
515 ret = persistent_ram_post_init(prz, sig, ecc_info);
521 persistent_ram_free(prz);