Refine support for the JEDEC Software Data Protection
This patch removes the extremely dangerous unprotect_jedec function
which is not used at all within flashrom code, and renames the
misleadingly named protect_jedec function to start_program_jedec.
Calls to protect_jedec after flashing are removed, because a) on LPC
chips, the command sent by protoct_jedec is not even in the datasheet
and b) on parallel chips, the block write command issued before already
contained the software protection sequence, so software protection is
definitely enabled.
This patch also removes two clones of protect_jedec
Background: JEDEC Software Data Protection started as an optional
feature, which was disabled on the first single-voltage-flash chips.
The software data protection is the need to prefix a write with a magic
"write enable" command, while without write protection every write
access into the chip's address space modifies flash content. This magic
write enable command also tells the flash chip that the programmer
obviously support sending write-enable commands and turns off the "any
write modifies flash content" mode. There also exist a two-command (6
writes) sequence that disables Software Data Protection completey, which
should only ever be used to prepare updating with a device that can't
handle software data protection.
Corresponding to flashrom svn r783.
Signed-off-by: Michael Karcher <flashrom@mkarcher.dialup.fu-berlin.de>
Acked-by: Sean Nelson <audiohacked@gmail.com>
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
diff --git a/jedec.c b/jedec.c
index f352c6b..0a5eda0 100644
--- a/jedec.c
+++ b/jedec.c
@@ -64,25 +64,11 @@
}
}
-void unprotect_jedec(chipaddr bios)
-{
- chip_writeb(0xAA, bios + 0x5555);
- chip_writeb(0x55, bios + 0x2AAA);
- chip_writeb(0x80, bios + 0x5555);
- chip_writeb(0xAA, bios + 0x5555);
- chip_writeb(0x55, bios + 0x2AAA);
- chip_writeb(0x20, bios + 0x5555);
-
- programmer_delay(200);
-}
-
-void protect_jedec(chipaddr bios)
+void start_program_jedec(chipaddr bios)
{
chip_writeb(0xAA, bios + 0x5555);
chip_writeb(0x55, bios + 0x2AAA);
chip_writeb(0xA0, bios + 0x5555);
-
- programmer_delay(200);
}
int probe_jedec(struct flashchip *flash)
@@ -270,9 +256,7 @@
retry:
/* Issue JEDEC Data Unprotect comand */
- chip_writeb(0xAA, bios + 0x5555);
- chip_writeb(0x55, bios + 0x2AAA);
- chip_writeb(0xA0, bios + 0x5555);
+ start_program_jedec(bios);
/* transfer data from source to destination */
for (i = 0; i < page_size; i++) {
@@ -312,9 +296,7 @@
retry:
/* Issue JEDEC Byte Program command */
- chip_writeb(0xAA, bios + 0x5555);
- chip_writeb(0x55, bios + 0x2AAA);
- chip_writeb(0xA0, bios + 0x5555);
+ start_program_jedec(bios);
/* transfer data from source to destination */
chip_writeb(*src, dst);
@@ -353,7 +335,6 @@
int i, failed = 0;
int total_size = flash->total_size * 1024;
int page_size = flash->page_size;
- chipaddr bios = flash->virtual_memory;
if (erase_chip_jedec(flash)) {
fprintf(stderr,"ERASE FAILED!\n");
@@ -369,7 +350,6 @@
printf("\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b");
}
printf("\n");
- protect_jedec(bios);
return failed;
}