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/*
* Copyright (C) 2012 Google, Inc.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/slab.h>
#include "persistent_ram.h"
#ifdef CONFIG_ANDROID_RAM_CONSOLE_ERROR_CORRECTION
#include <linux/rslib.h>
#endif
struct persistent_ram_buffer {
uint32_t sig;
uint32_t start;
uint32_t size;
uint8_t data[0];
};
#define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
static LIST_HEAD(zone_list);
#define ECC_BLOCK_SIZE CONFIG_ANDROID_RAM_CONSOLE_ERROR_CORRECTION_DATA_SIZE
#define ECC_SIZE CONFIG_ANDROID_RAM_CONSOLE_ERROR_CORRECTION_ECC_SIZE
#define ECC_SYMSIZE CONFIG_ANDROID_RAM_CONSOLE_ERROR_CORRECTION_SYMBOL_SIZE
#define ECC_POLY CONFIG_ANDROID_RAM_CONSOLE_ERROR_CORRECTION_POLYNOMIAL
#ifdef CONFIG_ANDROID_RAM_CONSOLE_ERROR_CORRECTION
static void persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
uint8_t *data, size_t len, uint8_t *ecc)
{
int i;
uint16_t par[ECC_SIZE];
/* Initialize the parity buffer */
memset(par, 0, sizeof(par));
encode_rs8(prz->rs_decoder, data, len, par, 0);
for (i = 0; i < ECC_SIZE; i++)
ecc[i] = par[i];
}
static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
void *data, size_t len, uint8_t *ecc)
{
int i;
uint16_t par[ECC_SIZE];
for (i = 0; i < ECC_SIZE; i++)
par[i] = ecc[i];
return decode_rs8(prz->rs_decoder, data, par, len,
NULL, 0, NULL, 0, NULL);
}
#endif
static void persistent_ram_update(struct persistent_ram_zone *prz,
const void *s, unsigned int count)
{
struct persistent_ram_buffer *buffer = prz->buffer;
#ifdef CONFIG_ANDROID_RAM_CONSOLE_ERROR_CORRECTION
uint8_t *buffer_end = buffer->data + prz->buffer_size;
uint8_t *block;
uint8_t *par;
int size = ECC_BLOCK_SIZE;
#endif
memcpy(buffer->data + buffer->start, s, count);
#ifdef CONFIG_ANDROID_RAM_CONSOLE_ERROR_CORRECTION
block = buffer->data + (buffer->start & ~(ECC_BLOCK_SIZE - 1));
par = prz->par_buffer +
(buffer->start / ECC_BLOCK_SIZE) * ECC_SIZE;
do {
if (block + ECC_BLOCK_SIZE > buffer_end)
size = buffer_end - block;
persistent_ram_encode_rs8(prz, block, size, par);
block += ECC_BLOCK_SIZE;
par += ECC_SIZE;
} while (block < buffer->data + buffer->start + count);
#endif
}
static void persistent_ram_update_header(struct persistent_ram_zone *prz)
{
#ifdef CONFIG_ANDROID_RAM_CONSOLE_ERROR_CORRECTION
struct persistent_ram_buffer *buffer = prz->buffer;
persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
prz->par_header);
#endif
}
static void __init
persistent_ram_save_old(struct persistent_ram_zone *prz)
{
struct persistent_ram_buffer *buffer = prz->buffer;
size_t old_log_size = buffer->size;
char *dest;
#ifdef CONFIG_ANDROID_RAM_CONSOLE_ERROR_CORRECTION
uint8_t *block;
uint8_t *par;
block = buffer->data;
par = prz->par_buffer;
while (block < buffer->data + buffer->size) {
int numerr;
int size = ECC_BLOCK_SIZE;
if (block + size > buffer->data + prz->buffer_size)
size = buffer->data + prz->buffer_size - block;
numerr = persistent_ram_decode_rs8(prz, block, size, par);
if (numerr > 0) {
#if 0
pr_info("persistent_ram: error in block %p, %d\n",
block, numerr);
#endif
prz->corrected_bytes += numerr;
} else if (numerr < 0) {
#if 0
pr_info("persistent_ram: uncorrectable error in block %p\n",
block);
#endif
prz->bad_blocks++;
}
block += ECC_BLOCK_SIZE;
par += ECC_SIZE;
}
#endif
dest = kmalloc(old_log_size, GFP_KERNEL);
if (dest == NULL) {
pr_err("persistent_ram: failed to allocate buffer\n");
return;
}
prz->old_log = dest;
prz->old_log_size = old_log_size;
memcpy(prz->old_log,
&buffer->data[buffer->start], buffer->size - buffer->start);
memcpy(prz->old_log + buffer->size - buffer->start,
&buffer->data[0], buffer->start);
}
int persistent_ram_write(struct persistent_ram_zone *prz,
const void *s, unsigned int count)
{
int rem;
int c = count;
struct persistent_ram_buffer *buffer = prz->buffer;
if (c > prz->buffer_size) {
s += c - prz->buffer_size;
c = prz->buffer_size;
}
rem = prz->buffer_size - buffer->start;
if (rem < c) {
persistent_ram_update(prz, s, rem);
s += rem;
c -= rem;
buffer->start = 0;
buffer->size = prz->buffer_size;
}
persistent_ram_update(prz, s, c);
buffer->start += c;
if (buffer->size < prz->buffer_size)
buffer->size += c;
persistent_ram_update_header(prz);
return count;
}
ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
char *str, size_t len)
{
#ifdef CONFIG_ANDROID_RAM_CONSOLE_ERROR_CORRECTION
ssize_t ret;
if (prz->corrected_bytes || prz->bad_blocks)
ret = snprintf(str, len, ""
"\n%d Corrected bytes, %d unrecoverable blocks\n",
prz->corrected_bytes, prz->bad_blocks);
else
ret = snprintf(str, len, "\nNo errors detected\n");
return ret;
#else
return 0;
#endif
}
size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
{
return prz->old_log_size;
}
void *persistent_ram_old(struct persistent_ram_zone *prz)
{
return prz->old_log;
}
void persistent_ram_free_old(struct persistent_ram_zone *prz)
{
kfree(prz->old_log);
prz->old_log = NULL;
prz->old_log_size = 0;
}
static int __init __persistent_ram_init(struct persistent_ram_zone *prz,
void __iomem *mem, size_t buffer_size)
{
struct persistent_ram_buffer *buffer = mem;
#ifdef CONFIG_ANDROID_RAM_CONSOLE_ERROR_CORRECTION
int numerr;
#endif
INIT_LIST_HEAD(&prz->node);
prz->buffer = buffer;
prz->buffer_size = buffer_size - sizeof(struct persistent_ram_buffer);
if (prz->buffer_size > buffer_size) {
pr_err("persistent_ram: buffer %p, invalid size %zu, datasize %zu\n",
buffer, buffer_size, prz->buffer_size);
return -EINVAL;
}
#ifdef CONFIG_ANDROID_RAM_CONSOLE_ERROR_CORRECTION
prz->buffer_size -= (DIV_ROUND_UP(prz->buffer_size,
ECC_BLOCK_SIZE) + 1) * ECC_SIZE;
if (prz->buffer_size > buffer_size) {
pr_err("persistent_ram: buffer %p, invalid size %zu, non-ecc datasize %zu\n",
buffer, buffer_size, prz->buffer_size);
return -EINVAL;
}
prz->par_buffer = buffer->data + prz->buffer_size;
prz->par_header = prz->par_buffer +
DIV_ROUND_UP(prz->buffer_size, ECC_BLOCK_SIZE) * ECC_SIZE;
/* first consecutive root is 0
* primitive element to generate roots = 1
*/
prz->rs_decoder = init_rs(ECC_SYMSIZE, ECC_POLY, 0, 1, ECC_SIZE);
if (prz->rs_decoder == NULL) {
pr_info("persistent_ram: init_rs failed\n");
return -EINVAL;
}
prz->corrected_bytes = 0;
prz->bad_blocks = 0;
numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
prz->par_header);
if (numerr > 0) {
pr_info("persistent_ram: error in header, %d\n", numerr);
prz->corrected_bytes += numerr;
} else if (numerr < 0) {
pr_info("persistent_ram: uncorrectable error in header\n");
prz->bad_blocks++;
}
#endif
if (buffer->sig == PERSISTENT_RAM_SIG) {
if (buffer->size > prz->buffer_size
|| buffer->start > buffer->size)
pr_info("persistent_ram: found existing invalid buffer, size %d, start %d\n",
buffer->size, buffer->start);
else {
pr_info("persistent_ram: found existing buffer, size %d, start %d\n",
buffer->size, buffer->start);
persistent_ram_save_old(prz);
}
} else {
pr_info("persistent_ram: no valid data in buffer (sig = 0x%08x)\n",
buffer->sig);
}
buffer->sig = PERSISTENT_RAM_SIG;
buffer->start = 0;
buffer->size = 0;
list_add_tail(&prz->node, &zone_list);
return 0;
}
int __init persistent_ram_init_ringbuffer(struct persistent_ram_zone *prz,
void __iomem *mem, size_t buffer_size)
{
return __persistent_ram_init(prz, mem, buffer_size);
}
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