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#include <linux/stddef.h>
#include <linux/string.h>
#include "interface.h"
#include "internals.h"
#include "id-errno.h"
#include "crc-15.h"
/* struct id_data id_data; */
struct __attribute__ ((packed)) id_header {
unsigned char signature[4];
unsigned char id_fmt_ver;
unsigned char unused0;
unsigned short data_length;
} ;
struct __attribute__ ((packed)) id_checksums {
unsigned short header;
unsigned short data;
} ;
int id_startup(struct id_data *data)
{
int i, err;
struct id_cookie cookie;
unsigned char byte, *p;
char *header_tag= "LpId";
unsigned short xsum;
struct id_header hdr;
struct id_checksums xsums;
unsigned char *mem_ptr = data->mem_ptr;
/* Clear out data->mem_ptr since we want all the fetches to come
* from the AT24 chip. Once we've validated the CRCs, restore
* data->mem_ptr to allow id_fetch_byte to read from data->mem_ptr
* instead of the AT24 chip. Should speed up accesses dramatically */
data->mem_ptr = NULL;
memset(&cookie, 0, sizeof(cookie));
/* Data starts with the header, should be 'LpId' */
for (i=0; i<4; ++i) {
byte = id_fetch_byte(NULL, cookie.offset, &err);
if (mem_ptr)
mem_ptr[cookie.offset] = byte;
hdr.signature[i] = byte;
cookie.offset++;
if (err != ID_EOK) {
id_printf("%s[%u]\n", __FILE__, __LINE__);
goto err_ret;
}
if (hdr.signature[i] != header_tag[i]) {
id_printf("%s[%u]\n", __FILE__, __LINE__);
err = ID_ENODEV;
goto err_ret;
}
}
/* First LE 8-bit value is ID format version */
byte = id_fetch_byte(NULL, cookie.offset, &err);
if (mem_ptr)
mem_ptr[cookie.offset] = byte;
hdr.id_fmt_ver = byte;
cookie.offset++;
/* Second LE 8-bit value is currently not used */
byte = id_fetch_byte(NULL, cookie.offset, &err);
if (mem_ptr)
mem_ptr[cookie.offset] = byte;
hdr.unused0 = byte;
cookie.offset++;
/* Next LE 16-bit value is length of data */
byte = id_fetch_byte(NULL, cookie.offset, &err);
if (mem_ptr)
mem_ptr[cookie.offset] = byte;
hdr.data_length = byte;
cookie.offset++;
byte = id_fetch_byte(NULL, cookie.offset, &err);
if (mem_ptr)
mem_ptr[cookie.offset] = byte;
hdr.data_length |= byte << 8;
cookie.offset++;
/* Next LE 16-bit value is xsum of header */
byte = id_fetch_byte(NULL, cookie.offset, &err);
if (mem_ptr)
mem_ptr[cookie.offset] = byte;
xsums.header = byte;
cookie.offset++;
byte = id_fetch_byte(NULL, cookie.offset, &err);
if (mem_ptr)
mem_ptr[cookie.offset] = byte;
xsums.header |= byte << 8;
cookie.offset++;
/* Checksum the header */
xsum = 0;
p = (unsigned char *)&hdr;
for (i = 0; i < sizeof(hdr); ++i)
crc_15_step(&xsum, p[i]);
if (xsum != xsums.header) {
id_printf("%s[%u] xsum: 0x%04x, xsums.header: 0x%04x\n",
__FILE__, __LINE__, xsum, xsums.header);
err = -ID_EL2NSYNC;
goto err_ret;
}
/* Next LE 16-bit value is xsum of data */
byte = id_fetch_byte(NULL, cookie.offset, &err);
if (mem_ptr)
mem_ptr[cookie.offset] = byte;
xsums.data = byte;
cookie.offset++;
byte = id_fetch_byte(NULL, cookie.offset, &err);
if (mem_ptr)
mem_ptr[cookie.offset] = byte;
xsums.data |= byte << 8;
cookie.offset++;
/* Checksum the data (next id_len bytes), must match xsums.data */
xsum = 0;
for (i = 0; i < hdr.data_length; ++i) {
byte = id_fetch_byte(NULL, cookie.offset + i, &err);
if (mem_ptr)
mem_ptr[cookie.offset + i] = byte;
if (err != ID_EOK) {
id_printf("%s[%u]\n", __FILE__, __LINE__);
goto err_ret;
}
crc_15_step(&xsum, byte);
}
if (xsum != xsums.data) {
id_printf("%s[%u] xsum: 0x%04x, xsums.data: 0x%04x\n",
__FILE__, __LINE__, xsum, xsums.data);
err = -ID_EL2NSYNC;
goto err_ret;
}
/* offset is now at the first byte of the root dictionary which
contains its span */
data->root_offset = cookie.offset;
data->root_size = extract_unsigned_pnum(&cookie, 5, &err);
if (err != ID_EOK) {
id_printf("%s[%u]\n", __FILE__, __LINE__);
goto err_ret;
}
data->root_size += cookie.offset - data->root_offset;
#if 0
id_printf("Data format version: %u\n", hdr.id_fmt_ver);
#endif
/* Restore data->mem_ptr to allow id_fetch_byte to read
* from the cached data instead of the AT24 chip */
data->mem_ptr = mem_ptr;
return ID_EOK;
err_ret:
/* Error return - make sure signature in SRAM is invalid */
if (mem_ptr)
mem_ptr[0] = 0;
return err;
}
/*
* Reset the cookie to cover the whole root dictionary
*/
int id_init_cookie(struct id_data *data, struct id_cookie *cookie)
{
if (!cookie)
return -ID_EINVAL;
cookie->mem_ptr = data->mem_ptr;
cookie->start_offset = data->root_offset;
cookie->size = data->root_size;
cookie->offset = cookie->start_offset;
return ID_EOK;
}
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