diff options
Diffstat (limited to 'resources/utilities/ich9deblob/gbe/gbe.h')
| -rw-r--r-- | resources/utilities/ich9deblob/gbe/gbe.h | 109 |
1 files changed, 66 insertions, 43 deletions
diff --git a/resources/utilities/ich9deblob/gbe/gbe.h b/resources/utilities/ich9deblob/gbe/gbe.h index b775534..de3b27d 100644 --- a/resources/utilities/ich9deblob/gbe/gbe.h +++ b/resources/utilities/ich9deblob/gbe/gbe.h @@ -19,12 +19,16 @@ * along with this program. If not, see <http://www.gnu.org/licenses/>. */ -// Purpose: provide struct representing gbe region. -// Map actual buffers of this regions, directly to instances of these -// structs. This makes working with gbe really easy. +/* + * Purpose: provide struct representing gbe region. + * Map actual buffers of this regions, directly to instances of these + * structs. This makes working with gbe really easy. + */ -// bit fields used, corresponding to datasheet. See links to datasheets -// and documentation in ich9deblob.c +/* + * bit fields used, corresponding to datasheet. See links to datasheets + * and documentation in ich9deblob.c + */ #ifndef GBESTRUCT_H #define GBESTRUCT_H @@ -32,55 +36,70 @@ #include <stdio.h> #include <string.h> -#define GBEREGIONSIZE 0x2000 // 8 KiB -// These will have a modified descriptor+gbe based on what's in the factory.rom -// These will be joined into a single 12KiB buffer (descriptor, then gbe) and saved to a file -// NOTE: The GBE region of 8K is actually 2x 4K regions in a single region; both 4K blocks can be identical (and by default, are) -// The 2nd one is a "backup", but we don't know when it's used. perhaps it's used when the checksum on the first one does not match? +/* Size of gbe region in bytes */ +#define GBEREGIONSIZE 0x2000 -// --------------------------------------------------------------------- -// Gbe struct representing the data -// --------------------------------------------------------------------- +/* + * These will have a modified descriptor+gbe based on what's in the factory.rom + * These will be joined into a single 12KiB buffer (descriptor, then gbe) and saved to a file + * NOTE: The GBE region of 8K is actually 2x 4K regions in a single region; both 4K blocks can be identical (and by default, are) + * The 2nd one is a "backup", but we don't know when it's used. perhaps it's used when the checksum on the first one does not match? + */ + +/* + * --------------------------------------------------------------------- + * Gbe struct representing the data: + * --------------------------------------------------------------------- + */ struct GBEREGIONRECORD_4K { - unsigned char macAddress[6]; // 0x03 words, or 0x06 bytes - unsigned char otherStuff[120]; // 0x3c words, or 0x7E bytes - unsigned short checkSum; // when added to the sum of all words above, this should be 0xBABA + unsigned char macAddress[6]; /* 0x03 words, or 0x06 bytes */ + unsigned char otherStuff[120]; /* 0x3c words, or 0x7E bytes */ + unsigned short checkSum; /* when added to the sum of all words above, this should be 0xBABA */ unsigned char padding1[3968]; }; -// main and backup region in gbe +/* main and backup region in gbe */ struct GBEREGIONRECORD_8K { struct GBEREGIONRECORD_4K main; struct GBEREGIONRECORD_4K backup; - // Backup region: - // This is actually "main" on X200, since the real main has a bad checksum - // and other errors. You should do what you need on this one (if modifying - // lenovobios's gbe region) and then copy to main + /* + * Backup region: + * This is actually "main" on X200, since the real main has a bad checksum + * and other errors. You should do what you need on this one (if modifying + * lenovobios's gbe region) and then copy to main + */ }; -// --------------------------------------------------------------------- -// Gbe functions -// --------------------------------------------------------------------- +/* + * --------------------------------------------------------------------- + * Gbe functions: + * --------------------------------------------------------------------- + */ -// Read a 16-bit unsigned int from a supplied region buffer +/* Read a 16-bit unsigned int from a supplied region buffer */ unsigned short gbeGetRegionWordFrom8kBuffer(int index, char* regionData) { return *((unsigned short*)(regionData + (index * 2))); } -// checksum calculation for 8k gbe region (algorithm based on datasheet) -// also works for 4k buffers, so long as isBackup remains false +/* + * checksum calculation for 8k gbe region (algorithm based on datasheet) + * also works for 4k buffers, so long as isBackup remains false + */ unsigned short gbeGetChecksumFrom8kBuffer(char* regionData, unsigned short desiredValue, char isBackup) { int i; - unsigned short regionWord; // store words here for adding to checksum - unsigned short checksum = 0; // this gbe's checksum - unsigned short offset = 0; // in bytes, from the start of the gbe region. + unsigned short regionWord; /* store words here for adding to checksum */ + unsigned short checksum = 0; /* this gbe's checksum */ + unsigned short offset = 0; /* in bytes, from the start of the gbe region. */ - // if isBackup is true, use 2nd gbe region ("backup" region) - if (isBackup) offset = 0x1000>>1; // this function uses *word* not *byte* indexes. + /* + * if isBackup is true, use 2nd gbe region ("backup" region) + * this function uses *word* not *byte* indexes, hence the bit shift. + */ + if (isBackup) offset = 0x1000>>1; for (i = 0; i < 0x3F; i++) { regionWord = gbeGetRegionWordFrom8kBuffer(i+offset, regionData); @@ -90,7 +109,7 @@ unsigned short gbeGetChecksumFrom8kBuffer(char* regionData, unsigned short desir return checksum; } -// checksum calculation for 4k gbe struct (algorithm based on datasheet) +/* checksum calculation for 4k gbe struct (algorithm based on datasheet) */ unsigned short gbeGetChecksumFrom4kStruct(struct GBEREGIONRECORD_4K gbeStruct4k, unsigned short desiredValue) { char gbeBuffer4k[GBEREGIONSIZE>>1]; @@ -98,12 +117,14 @@ unsigned short gbeGetChecksumFrom4kStruct(struct GBEREGIONRECORD_4K gbeStruct4k, return gbeGetChecksumFrom8kBuffer(gbeBuffer4k, desiredValue, 0); } -// modify the gbe region extracted from a factory.rom dump +/* modify the gbe region extracted from a factory.rom dump */ struct GBEREGIONRECORD_8K deblobbedGbeStructFromFactory(struct GBEREGIONRECORD_8K factoryGbeStruct8k) { - // Correct the main gbe region. By default, the X200 (as shipped from Lenovo) comes - // with a broken main gbe region, where the backup gbe region is used instead. Modify - // the descriptor so that the main region is usable. + /* + * Correct the main gbe region. By default, the X200 (as shipped from Lenovo) comes + * with a broken main gbe region, where the backup gbe region is used instead. Modify + * it so that the main region is usable. + */ struct GBEREGIONRECORD_8K deblobbedGbeStruct8k; memcpy(&deblobbedGbeStruct8k, &factoryGbeStruct8k, GBEREGIONSIZE); @@ -111,12 +132,14 @@ struct GBEREGIONRECORD_8K deblobbedGbeStructFromFactory(struct GBEREGIONRECORD_8 deblobbedGbeStruct8k.backup.checkSum = gbeGetChecksumFrom4kStruct(deblobbedGbeStruct8k.backup, 0xBABA); memcpy(&deblobbedGbeStruct8k.main, &deblobbedGbeStruct8k.backup, GBEREGIONSIZE>>1); - // Debugging: - // calculate the 0x3F'th 16-bit uint to make the desired final checksum for GBe - // observed checksum matches (from X200 factory.rom dumps) on main: 0x3ABA 0x34BA 0x40BA. spec defined as 0xBABA. - // X200 ships with a broken main gbe region by default (invalid checksum, and more) - // The "backup" gbe regions on these machines are correct, though, and is what the machines default to - // For libreboot's purpose, we can do much better than that by fixing the main one... below is only debugging + /* + * Debugging: + * calculate the 0x3F'th 16-bit uint to make the desired final checksum for GBe + * observed checksum matches (from X200 factory.rom dumps) on main: 0x3ABA 0x34BA 0x40BA. spec defined as 0xBABA. + * X200 ships with a broken main gbe region by default (invalid checksum, and more) + * The "backup" gbe regions on these machines are correct, though, and is what the machines default to + * For libreboot's purpose, we can do much better than that by fixing the main one... below is only debugging + */ printf("\nfactory Gbe (main): calculated Gbe checksum: 0x%hx and actual GBe checksum: 0x%hx\n", gbeGetChecksumFrom4kStruct(factoryGbeStruct8k.main, 0xBABA), factoryGbeStruct8k.main.checkSum); printf("factory Gbe (backup) calculated Gbe checksum: 0x%hx and actual GBe checksum: 0x%hx\n", gbeGetChecksumFrom4kStruct(factoryGbeStruct8k.backup, 0xBABA), factoryGbeStruct8k.backup.checkSum); printf("\ndeblobbed Gbe (main): calculated Gbe checksum: 0x%hx and actual GBe checksum: 0x%hx\n", gbeGetChecksumFrom4kStruct(deblobbedGbeStruct8k.main, 0xBABA), deblobbedGbeStruct8k.main.checkSum); |