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/* Copyright 2013-2014 IBM Corp.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <skiboot.h>
#include <nvram-format.h>
/*
* NVRAM Format as specified in PAPR
*/
struct chrp_nvram_hdr {
uint8_t sig;
uint8_t cksum;
uint16_t len;
char name[12];
};
#define NVRAM_SIG_FW_PRIV 0x51
#define NVRAM_SIG_SYSTEM 0x70
#define NVRAM_SIG_FREE 0x7f
#define NVRAM_NAME_COMMON "common"
#define NVRAM_NAME_FW_PRIV "ibm,skiboot"
#define NVRAM_NAME_FREE "wwwwwwwwwwww"
/* 64k should be enough, famous last words... */
#define NVRAM_SIZE_COMMON 0x10000
/* 4k should be enough, famous last words... */
#define NVRAM_SIZE_FW_PRIV 0x1000
static uint8_t chrp_nv_cksum(struct chrp_nvram_hdr *hdr)
{
struct chrp_nvram_hdr h_copy = *hdr;
uint8_t b_data, i_sum, c_sum;
uint8_t *p = (uint8_t *)&h_copy;
unsigned int nbytes = sizeof(h_copy);
h_copy.cksum = 0;
for (c_sum = 0; nbytes; nbytes--) {
b_data = *(p++);
i_sum = c_sum + b_data;
if (i_sum < c_sum)
i_sum++;
c_sum = i_sum;
}
return c_sum;
}
int nvram_format(void *nvram_image, uint32_t nvram_size)
{
struct chrp_nvram_hdr *h;
unsigned int offset = 0;
prerror("NVRAM: Re-initializing\n");
memset(nvram_image, 0, nvram_size);
/* Create private partition */
if (nvram_size - offset < NVRAM_SIZE_FW_PRIV)
return -1;
h = nvram_image + offset;
h->sig = NVRAM_SIG_FW_PRIV;
h->len = NVRAM_SIZE_FW_PRIV >> 4;
strcpy(h->name, NVRAM_NAME_FW_PRIV);
h->cksum = chrp_nv_cksum(h);
offset += NVRAM_SIZE_FW_PRIV;
/* Create common partition */
if (nvram_size - offset < NVRAM_SIZE_COMMON)
return -1;
h = nvram_image + offset;
h->sig = NVRAM_SIG_SYSTEM;
h->len = NVRAM_SIZE_COMMON >> 4;
strcpy(h->name, NVRAM_NAME_COMMON);
h->cksum = chrp_nv_cksum(h);
offset += NVRAM_SIZE_COMMON;
/* Create free space partition */
if (nvram_size - offset < sizeof(struct chrp_nvram_hdr))
return -1;
h = nvram_image + offset;
h->sig = NVRAM_SIG_FREE;
h->len = (nvram_size - offset) >> 4;
/* We have the full 12 bytes here */
memcpy(h->name, NVRAM_NAME_FREE, 12);
h->cksum = chrp_nv_cksum(h);
return 0;
}
/*
* Check that the nvram partition layout is sane and that it
* contains our required partitions. If not, we re-format the
* lot of it
*/
int nvram_check(void *nvram_image, const uint32_t nvram_size)
{
unsigned int offset = 0;
bool found_common = false;
bool found_skiboot = false;
while (offset + sizeof(struct chrp_nvram_hdr) < nvram_size) {
struct chrp_nvram_hdr *h = nvram_image + offset;
if (chrp_nv_cksum(h) != h->cksum) {
prerror("NVRAM: Partition at offset 0x%x"
" has bad checksum\n", offset);
goto failed;
}
if (h->len < 1) {
prerror("NVRAM: Partition at offset 0x%x"
" has incorrect 0 length\n", offset);
goto failed;
}
if (h->sig == NVRAM_SIG_SYSTEM &&
strcmp(h->name, NVRAM_NAME_COMMON) == 0)
found_common = true;
if (h->sig == NVRAM_SIG_FW_PRIV &&
strcmp(h->name, NVRAM_NAME_FW_PRIV) == 0)
found_skiboot = true;
offset += h->len << 4;
if (offset > nvram_size) {
prerror("NVRAM: Partition at offset 0x%x"
" extends beyond end of nvram !\n", offset);
goto failed;
}
}
if (!found_common) {
prerror("NVRAM: Common partition not found !\n");
goto failed;
}
if (!found_skiboot) {
prerror("NVRAM: Skiboot private partition "
"not found !\n");
goto failed;
}
prerror("NVRAM: Layout appears sane\n");
return 0;
failed:
return -1;
}
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