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 "persistent_ram.h"
28 struct persistent_ram_buffer {
35 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
37 static __initdata LIST_HEAD(persistent_ram_list);
39 static inline size_t buffer_size(struct persistent_ram_zone *prz)
41 return atomic_read(&prz->buffer->size);
44 static inline size_t buffer_start(struct persistent_ram_zone *prz)
46 return atomic_read(&prz->buffer->start);
49 /* increase and wrap the start pointer, returning the old value */
50 static inline size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
56 old = atomic_read(&prz->buffer->start);
58 while (unlikely(new > prz->buffer_size))
59 new -= prz->buffer_size;
60 } while (atomic_cmpxchg(&prz->buffer->start, old, new) != old);
65 /* increase the size counter until it hits the max size */
66 static inline void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
71 if (atomic_read(&prz->buffer->size) == prz->buffer_size)
75 old = atomic_read(&prz->buffer->size);
77 if (new > prz->buffer_size)
78 new = prz->buffer_size;
79 } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
82 /* increase the size counter, retuning an error if it hits the max size */
83 static inline ssize_t buffer_size_add_clamp(struct persistent_ram_zone *prz,
90 old = atomic_read(&prz->buffer->size);
92 if (new > prz->buffer_size)
94 } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
99 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
100 uint8_t *data, size_t len, uint8_t *ecc)
103 uint16_t par[prz->ecc_size];
105 /* Initialize the parity buffer */
106 memset(par, 0, sizeof(par));
107 encode_rs8(prz->rs_decoder, data, len, par, 0);
108 for (i = 0; i < prz->ecc_size; i++)
112 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
113 void *data, size_t len, uint8_t *ecc)
116 uint16_t par[prz->ecc_size];
118 for (i = 0; i < prz->ecc_size; i++)
120 return decode_rs8(prz->rs_decoder, data, par, len,
121 NULL, 0, NULL, 0, NULL);
124 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
125 unsigned int start, unsigned int count)
127 struct persistent_ram_buffer *buffer = prz->buffer;
128 uint8_t *buffer_end = buffer->data + prz->buffer_size;
131 int ecc_block_size = prz->ecc_block_size;
132 int ecc_size = prz->ecc_size;
133 int size = prz->ecc_block_size;
138 block = buffer->data + (start & ~(ecc_block_size - 1));
139 par = prz->par_buffer + (start / ecc_block_size) * prz->ecc_size;
142 if (block + ecc_block_size > buffer_end)
143 size = buffer_end - block;
144 persistent_ram_encode_rs8(prz, block, size, par);
145 block += ecc_block_size;
147 } while (block < buffer->data + start + count);
150 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
152 struct persistent_ram_buffer *buffer = prz->buffer;
157 persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
161 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
163 struct persistent_ram_buffer *buffer = prz->buffer;
170 block = buffer->data;
171 par = prz->par_buffer;
172 while (block < buffer->data + buffer_size(prz)) {
174 int size = prz->ecc_block_size;
175 if (block + size > buffer->data + prz->buffer_size)
176 size = buffer->data + prz->buffer_size - block;
177 numerr = persistent_ram_decode_rs8(prz, block, size, par);
179 pr_devel("persistent_ram: error in block %p, %d\n",
181 prz->corrected_bytes += numerr;
182 } else if (numerr < 0) {
183 pr_devel("persistent_ram: uncorrectable error in block %p\n",
187 block += prz->ecc_block_size;
188 par += prz->ecc_size;
192 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
196 struct persistent_ram_buffer *buffer = prz->buffer;
202 prz->ecc_block_size = 128;
204 prz->ecc_symsize = 8;
205 prz->ecc_poly = 0x11d;
207 ecc_blocks = DIV_ROUND_UP(prz->buffer_size, prz->ecc_block_size);
208 prz->buffer_size -= (ecc_blocks + 1) * prz->ecc_size;
210 if (prz->buffer_size > buffer_size) {
211 pr_err("persistent_ram: invalid size %zu, non-ecc datasize %zu\n",
212 buffer_size, prz->buffer_size);
216 prz->par_buffer = buffer->data + prz->buffer_size;
217 prz->par_header = prz->par_buffer + ecc_blocks * prz->ecc_size;
220 * first consecutive root is 0
221 * primitive element to generate roots = 1
223 prz->rs_decoder = init_rs(prz->ecc_symsize, prz->ecc_poly, 0, 1,
225 if (prz->rs_decoder == NULL) {
226 pr_info("persistent_ram: init_rs failed\n");
230 prz->corrected_bytes = 0;
233 numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
236 pr_info("persistent_ram: error in header, %d\n", numerr);
237 prz->corrected_bytes += numerr;
238 } else if (numerr < 0) {
239 pr_info("persistent_ram: 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->corrected_bytes || prz->bad_blocks)
252 ret = snprintf(str, len, ""
253 "\n%d Corrected bytes, %d unrecoverable blocks\n",
254 prz->corrected_bytes, prz->bad_blocks);
256 ret = snprintf(str, len, "\nNo errors detected\n");
261 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
262 const void *s, unsigned int start, unsigned int count)
264 struct persistent_ram_buffer *buffer = prz->buffer;
265 memcpy(buffer->data + start, s, count);
266 persistent_ram_update_ecc(prz, start, count);
270 persistent_ram_save_old(struct persistent_ram_zone *prz)
272 struct persistent_ram_buffer *buffer = prz->buffer;
273 size_t size = buffer_size(prz);
274 size_t start = buffer_start(prz);
277 persistent_ram_ecc_old(prz);
279 dest = kmalloc(size, GFP_KERNEL);
281 pr_err("persistent_ram: failed to allocate buffer\n");
286 prz->old_log_size = size;
287 memcpy(prz->old_log, &buffer->data[start], size - start);
288 memcpy(prz->old_log + size - start, &buffer->data[0], start);
291 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
292 const void *s, unsigned int count)
298 if (unlikely(c > prz->buffer_size)) {
299 s += c - prz->buffer_size;
300 c = prz->buffer_size;
303 buffer_size_add_clamp(prz, c);
305 start = buffer_start_add(prz, c);
307 rem = prz->buffer_size - start;
308 if (unlikely(rem < c)) {
309 persistent_ram_update(prz, s, start, rem);
314 persistent_ram_update(prz, s, start, c);
316 persistent_ram_update_header_ecc(prz);
321 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
323 return prz->old_log_size;
326 void *persistent_ram_old(struct persistent_ram_zone *prz)
331 void persistent_ram_free_old(struct persistent_ram_zone *prz)
335 prz->old_log_size = 0;
338 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
339 struct persistent_ram_zone *prz)
342 phys_addr_t page_start;
343 unsigned int page_count;
347 page_start = start - offset_in_page(start);
348 page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
350 prot = pgprot_noncached(PAGE_KERNEL);
352 pages = kmalloc(sizeof(struct page *) * page_count, GFP_KERNEL);
354 pr_err("%s: Failed to allocate array for %u pages\n", __func__,
359 for (i = 0; i < page_count; i++) {
360 phys_addr_t addr = page_start + i * PAGE_SIZE;
361 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
363 prz->vaddr = vmap(pages, page_count, VM_MAP, prot);
366 pr_err("%s: Failed to map %u pages\n", __func__, page_count);
370 prz->buffer = prz->vaddr + offset_in_page(start);
371 prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
376 static int __init persistent_ram_buffer_init(const char *name,
377 struct persistent_ram_zone *prz)
380 struct persistent_ram *ram;
381 struct persistent_ram_descriptor *desc;
384 list_for_each_entry(ram, &persistent_ram_list, node) {
386 for (i = 0; i < ram->num_descs; i++) {
387 desc = &ram->descs[i];
388 if (!strcmp(desc->name, name))
389 return persistent_ram_buffer_map(start,
399 struct persistent_ram_zone *__persistent_ram_init(struct device *dev, bool ecc)
401 struct persistent_ram_zone *prz;
404 prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
406 pr_err("persistent_ram: failed to allocate persistent ram zone\n");
407 return ERR_PTR(-ENOMEM);
410 INIT_LIST_HEAD(&prz->node);
412 ret = persistent_ram_buffer_init(dev_name(dev), prz);
414 pr_err("persistent_ram: failed to initialize buffer\n");
419 ret = persistent_ram_init_ecc(prz, prz->buffer_size);
423 if (prz->buffer->sig == PERSISTENT_RAM_SIG) {
424 if (buffer_size(prz) > prz->buffer_size ||
425 buffer_start(prz) > buffer_size(prz))
426 pr_info("persistent_ram: found existing invalid buffer,"
427 " size %ld, start %ld\n",
428 buffer_size(prz), buffer_start(prz));
430 pr_info("persistent_ram: found existing buffer,"
431 " size %ld, start %ld\n",
432 buffer_size(prz), buffer_start(prz));
433 persistent_ram_save_old(prz);
436 pr_info("persistent_ram: no valid data in buffer"
437 " (sig = 0x%08x)\n", prz->buffer->sig);
440 prz->buffer->sig = PERSISTENT_RAM_SIG;
441 atomic_set(&prz->buffer->start, 0);
442 atomic_set(&prz->buffer->size, 0);
447 struct persistent_ram_zone * __init
448 persistent_ram_init_ringbuffer(struct device *dev, bool ecc)
450 return __persistent_ram_init(dev, ecc);
453 int __init persistent_ram_early_init(struct persistent_ram *ram)
457 ret = memblock_reserve(ram->start, ram->size);
459 pr_err("Failed to reserve persistent memory from %08lx-%08lx\n",
460 (long)ram->start, (long)(ram->start + ram->size - 1));
464 list_add_tail(&ram->node, &persistent_ram_list);
466 pr_info("Initialized persistent memory from %08lx-%08lx\n",
467 (long)ram->start, (long)(ram->start + ram->size - 1));