diff --git a/drivers/firmware/google/vpd_decode.c b/drivers/firmware/google/vpd_decode.c new file mode 100644 index 000000000000..943acaa8aa76 --- /dev/null +++ b/drivers/firmware/google/vpd_decode.c @@ -0,0 +1,99 @@ +/* + * vpd_decode.c + * + * Google VPD decoding routines. + * + * Copyright 2017 Google Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License v2.0 as published by + * the Free Software Foundation. + * + * 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 + +#include "vpd_decode.h" + +static int vpd_decode_len(const s32 max_len, const u8 *in, + s32 *length, s32 *decoded_len) +{ + u8 more; + int i = 0; + + if (!length || !decoded_len) + return VPD_FAIL; + + *length = 0; + do { + if (i >= max_len) + return VPD_FAIL; + + more = in[i] & 0x80; + *length <<= 7; + *length |= in[i] & 0x7f; + ++i; + } while (more); + + *decoded_len = i; + + return VPD_OK; +} + +int vpd_decode_string(const s32 max_len, const u8 *input_buf, s32 *consumed, + vpd_decode_callback callback, void *callback_arg) +{ + int type; + int res; + s32 key_len; + s32 value_len; + s32 decoded_len; + const u8 *key; + const u8 *value; + + /* type */ + if (*consumed >= max_len) + return VPD_FAIL; + + type = input_buf[*consumed]; + + switch (type) { + case VPD_TYPE_INFO: + case VPD_TYPE_STRING: + (*consumed)++; + + /* key */ + res = vpd_decode_len(max_len - *consumed, &input_buf[*consumed], + &key_len, &decoded_len); + if (res != VPD_OK || *consumed + decoded_len >= max_len) + return VPD_FAIL; + + *consumed += decoded_len; + key = &input_buf[*consumed]; + *consumed += key_len; + + /* value */ + res = vpd_decode_len(max_len - *consumed, &input_buf[*consumed], + &value_len, &decoded_len); + if (res != VPD_OK || *consumed + decoded_len > max_len) + return VPD_FAIL; + + *consumed += decoded_len; + value = &input_buf[*consumed]; + *consumed += value_len; + + if (type == VPD_TYPE_STRING) + return callback(key, key_len, value, value_len, + callback_arg); + break; + + default: + return VPD_FAIL; + } + + return VPD_OK; +} diff --git a/drivers/firmware/google/vpd_decode.h b/drivers/firmware/google/vpd_decode.h new file mode 100644 index 000000000000..be3d62c5ca2f --- /dev/null +++ b/drivers/firmware/google/vpd_decode.h @@ -0,0 +1,58 @@ +/* + * vpd_decode.h + * + * Google VPD decoding routines. + * + * Copyright 2017 Google Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License v2.0 as published by + * the Free Software Foundation. + * + * 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. + */ + +#ifndef __VPD_DECODE_H +#define __VPD_DECODE_H + +#include + +enum { + VPD_OK = 0, + VPD_FAIL, +}; + +enum { + VPD_TYPE_TERMINATOR = 0, + VPD_TYPE_STRING, + VPD_TYPE_INFO = 0xfe, + VPD_TYPE_IMPLICIT_TERMINATOR = 0xff, +}; + +/* Callback for vpd_decode_string to invoke. */ +typedef int vpd_decode_callback(const u8 *key, s32 key_len, + const u8 *value, s32 value_len, + void *arg); + +/* + * vpd_decode_string + * + * Given the encoded string, this function invokes callback with extracted + * (key, value). The *consumed will be plused the number of bytes consumed in + * this function. + * + * The input_buf points to the first byte of the input buffer. + * + * The *consumed starts from 0, which is actually the next byte to be decoded. + * It can be non-zero to be used in multiple calls. + * + * If one entry is successfully decoded, sends it to callback and returns the + * result. + */ +int vpd_decode_string(const s32 max_len, const u8 *input_buf, s32 *consumed, + vpd_decode_callback callback, void *callback_arg); + +#endif /* __VPD_DECODE_H */