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 #include <linux/device.h>
16 #include <linux/err.h>
17 #include <linux/errno.h>
18 #include <linux/kernel.h>
19 #include <linux/init.h>
21 #include <linux/list.h>
22 #include <linux/memblock.h>
23 #include <linux/rslib.h>
24 #include <linux/slab.h>
25 #include <linux/vmalloc.h>
26 #include <linux/pstore_ram.h>
29 struct persistent_ram_buffer {
36 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
38 static inline size_t buffer_size(struct persistent_ram_zone *prz)
40 return atomic_read(&prz->buffer->size);
43 static inline size_t buffer_start(struct persistent_ram_zone *prz)
45 return atomic_read(&prz->buffer->start);
48 /* increase and wrap the start pointer, returning the old value */
49 static inline size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
55 old = atomic_read(&prz->buffer->start);
57 while (unlikely(new > prz->buffer_size))
58 new -= prz->buffer_size;
59 } while (atomic_cmpxchg(&prz->buffer->start, old, new) != old);
64 /* increase the size counter until it hits the max size */
65 static inline void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
70 if (atomic_read(&prz->buffer->size) == prz->buffer_size)
74 old = atomic_read(&prz->buffer->size);
76 if (new > prz->buffer_size)
77 new = prz->buffer_size;
78 } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
81 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
82 uint8_t *data, size_t len, uint8_t *ecc)
85 uint16_t par[prz->ecc_size];
87 /* Initialize the parity buffer */
88 memset(par, 0, sizeof(par));
89 encode_rs8(prz->rs_decoder, data, len, par, 0);
90 for (i = 0; i < prz->ecc_size; i++)
94 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
95 void *data, size_t len, uint8_t *ecc)
98 uint16_t par[prz->ecc_size];
100 for (i = 0; i < prz->ecc_size; i++)
102 return decode_rs8(prz->rs_decoder, data, par, len,
103 NULL, 0, NULL, 0, NULL);
106 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
107 unsigned int start, unsigned int count)
109 struct persistent_ram_buffer *buffer = prz->buffer;
110 uint8_t *buffer_end = buffer->data + prz->buffer_size;
113 int ecc_block_size = prz->ecc_block_size;
114 int ecc_size = prz->ecc_size;
115 int size = prz->ecc_block_size;
120 block = buffer->data + (start & ~(ecc_block_size - 1));
121 par = prz->par_buffer + (start / ecc_block_size) * prz->ecc_size;
124 if (block + ecc_block_size > buffer_end)
125 size = buffer_end - block;
126 persistent_ram_encode_rs8(prz, block, size, par);
127 block += ecc_block_size;
129 } while (block < buffer->data + start + count);
132 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
134 struct persistent_ram_buffer *buffer = prz->buffer;
139 persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
143 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
145 struct persistent_ram_buffer *buffer = prz->buffer;
152 block = buffer->data;
153 par = prz->par_buffer;
154 while (block < buffer->data + buffer_size(prz)) {
156 int size = prz->ecc_block_size;
157 if (block + size > buffer->data + prz->buffer_size)
158 size = buffer->data + prz->buffer_size - block;
159 numerr = persistent_ram_decode_rs8(prz, block, size, par);
161 pr_devel("persistent_ram: error in block %p, %d\n",
163 prz->corrected_bytes += numerr;
164 } else if (numerr < 0) {
165 pr_devel("persistent_ram: uncorrectable error in block %p\n",
169 block += prz->ecc_block_size;
170 par += prz->ecc_size;
174 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
178 struct persistent_ram_buffer *buffer = prz->buffer;
182 int ecc_poly = 0x11d;
187 prz->ecc_block_size = 128;
188 prz->ecc_size = ecc_size;
190 ecc_blocks = DIV_ROUND_UP(prz->buffer_size, prz->ecc_block_size);
191 ecc_total = (ecc_blocks + 1) * prz->ecc_size;
192 if (ecc_total >= prz->buffer_size) {
193 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
194 __func__, prz->ecc_size, ecc_total, prz->buffer_size);
198 prz->buffer_size -= ecc_total;
199 prz->par_buffer = buffer->data + prz->buffer_size;
200 prz->par_header = prz->par_buffer + ecc_blocks * prz->ecc_size;
203 * first consecutive root is 0
204 * primitive element to generate roots = 1
206 prz->rs_decoder = init_rs(ecc_symsize, ecc_poly, 0, 1, prz->ecc_size);
207 if (prz->rs_decoder == NULL) {
208 pr_info("persistent_ram: init_rs failed\n");
212 prz->corrected_bytes = 0;
215 numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
218 pr_info("persistent_ram: error in header, %d\n", numerr);
219 prz->corrected_bytes += numerr;
220 } else if (numerr < 0) {
221 pr_info("persistent_ram: uncorrectable error in header\n");
228 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
229 char *str, size_t len)
233 if (prz->corrected_bytes || prz->bad_blocks)
234 ret = snprintf(str, len, ""
235 "\n%d Corrected bytes, %d unrecoverable blocks\n",
236 prz->corrected_bytes, prz->bad_blocks);
238 ret = snprintf(str, len, "\nNo errors detected\n");
243 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
244 const void *s, unsigned int start, unsigned int count)
246 struct persistent_ram_buffer *buffer = prz->buffer;
247 memcpy(buffer->data + start, s, count);
248 persistent_ram_update_ecc(prz, start, count);
251 void persistent_ram_save_old(struct persistent_ram_zone *prz)
253 struct persistent_ram_buffer *buffer = prz->buffer;
254 size_t size = buffer_size(prz);
255 size_t start = buffer_start(prz);
261 persistent_ram_ecc_old(prz);
262 prz->old_log = kmalloc(size, GFP_KERNEL);
265 pr_err("persistent_ram: failed to allocate buffer\n");
269 prz->old_log_size = size;
270 memcpy(prz->old_log, &buffer->data[start], size - start);
271 memcpy(prz->old_log + size - start, &buffer->data[0], start);
274 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
275 const void *s, unsigned int count)
281 if (unlikely(c > prz->buffer_size)) {
282 s += c - prz->buffer_size;
283 c = prz->buffer_size;
286 buffer_size_add(prz, c);
288 start = buffer_start_add(prz, c);
290 rem = prz->buffer_size - start;
291 if (unlikely(rem < c)) {
292 persistent_ram_update(prz, s, start, rem);
297 persistent_ram_update(prz, s, start, c);
299 persistent_ram_update_header_ecc(prz);
304 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
306 return prz->old_log_size;
309 void *persistent_ram_old(struct persistent_ram_zone *prz)
314 void persistent_ram_free_old(struct persistent_ram_zone *prz)
318 prz->old_log_size = 0;
321 void persistent_ram_zap(struct persistent_ram_zone *prz)
323 atomic_set(&prz->buffer->start, 0);
324 atomic_set(&prz->buffer->size, 0);
325 persistent_ram_update_header_ecc(prz);
328 static void *persistent_ram_vmap(phys_addr_t start, size_t size)
331 phys_addr_t page_start;
332 unsigned int page_count;
337 page_start = start - offset_in_page(start);
338 page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
340 prot = pgprot_noncached(PAGE_KERNEL);
342 pages = kmalloc(sizeof(struct page *) * page_count, GFP_KERNEL);
344 pr_err("%s: Failed to allocate array for %u pages\n", __func__,
349 for (i = 0; i < page_count; i++) {
350 phys_addr_t addr = page_start + i * PAGE_SIZE;
351 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
353 vaddr = vmap(pages, page_count, VM_MAP, prot);
359 static void *persistent_ram_iomap(phys_addr_t start, size_t size)
361 if (!request_mem_region(start, size, "persistent_ram")) {
362 pr_err("request mem region (0x%llx@0x%llx) failed\n",
363 (unsigned long long)size, (unsigned long long)start);
367 return ioremap(start, size);
370 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
371 struct persistent_ram_zone *prz)
376 if (pfn_valid(start >> PAGE_SHIFT))
377 prz->vaddr = persistent_ram_vmap(start, size);
379 prz->vaddr = persistent_ram_iomap(start, size);
382 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
383 (unsigned long long)size, (unsigned long long)start);
387 prz->buffer = prz->vaddr + offset_in_page(start);
388 prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
393 static int __devinit persistent_ram_post_init(struct persistent_ram_zone *prz,
394 u32 sig, int ecc_size)
398 ret = persistent_ram_init_ecc(prz, ecc_size);
402 sig ^= PERSISTENT_RAM_SIG;
404 if (prz->buffer->sig == sig) {
405 if (buffer_size(prz) > prz->buffer_size ||
406 buffer_start(prz) > buffer_size(prz))
407 pr_info("persistent_ram: found existing invalid buffer,"
408 " size %zu, start %zu\n",
409 buffer_size(prz), buffer_start(prz));
411 pr_debug("persistent_ram: found existing buffer,"
412 " size %zu, start %zu\n",
413 buffer_size(prz), buffer_start(prz));
414 persistent_ram_save_old(prz);
418 pr_debug("persistent_ram: no valid data in buffer"
419 " (sig = 0x%08x)\n", prz->buffer->sig);
422 prz->buffer->sig = sig;
423 persistent_ram_zap(prz);
428 void persistent_ram_free(struct persistent_ram_zone *prz)
434 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
438 release_mem_region(prz->paddr, prz->size);
442 persistent_ram_free_old(prz);
446 struct persistent_ram_zone * __devinit persistent_ram_new(phys_addr_t start,
447 size_t size, u32 sig,
450 struct persistent_ram_zone *prz;
453 prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
455 pr_err("persistent_ram: failed to allocate persistent ram zone\n");
459 ret = persistent_ram_buffer_map(start, size, prz);
463 ret = persistent_ram_post_init(prz, sig, ecc_size);
469 persistent_ram_free(prz);