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>

6 files changed, 4 insertions, 50 deletions

diff --git a/82802ab.c b/82802ab.c
index b274d56..58d3467 100644
--- a/82802ab.c
+++ b/82802ab.c
@@ -190,7 +190,6 @@ int write_82802ab(struct flashchip *flash, uint8_t *buf)
 				   bios + i * page_size, page_size);
 	}
 	printf("\n");
-	protect_jedec(bios);
 	free(tmpbuf);
 
 	return 0;
diff --git a/flash.h b/flash.h
index 008af28..1a1d8f8 100644
--- a/flash.h
+++ b/flash.h
@@ -647,8 +647,7 @@ extern uint8_t *sb600_spibar;
 uint8_t oddparity(uint8_t val);
 void toggle_ready_jedec(chipaddr dst);
 void data_polling_jedec(chipaddr dst, uint8_t data);
-void unprotect_jedec(chipaddr bios);
-void protect_jedec(chipaddr bios);
+void start_program_jedec(chipaddr bios);
 int write_byte_program_jedec(chipaddr bios, uint8_t *src,
 			     chipaddr dst);
 int probe_jedec(struct flashchip *flash);
diff --git a/jedec.c b/jedec.c
index f352c6b..0a5eda0 100644
--- a/jedec.c
+++ b/jedec.c
@@ -64,25 +64,11 @@ void data_polling_jedec(chipaddr dst, uint8_t data)
 	}
 }
 
-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 @@ int write_page_write_jedec(struct flashchip *flash, uint8_t *src,
 
 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 @@ int write_byte_program_jedec(chipaddr bios, uint8_t *src,
 
 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 write_jedec(struct flashchip *flash, uint8_t *buf)
 	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 @@ int write_jedec(struct flashchip *flash, uint8_t *buf)
 		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;
 }
diff --git a/m29f400bt.c b/m29f400bt.c
index 28e5da4..5c36db9 100644
--- a/m29f400bt.c
+++ b/m29f400bt.c
@@ -20,15 +20,6 @@
 
 #include "flash.h"
 
-void protect_m29f400bt(chipaddr bios)
-{
-	chip_writeb(0xAA, bios + 0xAAA);
-	chip_writeb(0x55, bios + 0x555);
-	chip_writeb(0xA0, bios + 0xAAA);
-
-	programmer_delay(200);
-}
-
 void write_page_m29f400bt(chipaddr bios, uint8_t *src,
 			  chipaddr dst, int page_size)
 {
@@ -194,7 +185,6 @@ int write_m29f400bt(struct flashchip *flash, uint8_t *buf)
 	write_page_m29f400bt(bios, buf + 0x7c000, bios + 0x7c000, 16 * 1024);
 
 	printf("\n");
-	//protect_m29f400bt (bios);
 
 	return 0;
 }
@@ -248,7 +238,6 @@ int write_coreboot_m29f400bt(struct flashchip *flash, uint8_t *buf)
 	write_page_m29f400bt(bios, buf + 0x30000, bios + 0x30000, 64 * 1024);
 
 	printf("\n");
-	//protect_m29f400bt (bios);
 
 	return 0;
 }
diff --git a/sharplhf00l04.c b/sharplhf00l04.c
index c4c0f03..1234ae4 100644
--- a/sharplhf00l04.c
+++ b/sharplhf00l04.c
@@ -179,7 +179,6 @@ int write_lhf00l04(struct flashchip *flash, uint8_t *buf)
 		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 0;
 }
diff --git a/stm50flw0x0x.c b/stm50flw0x0x.c
index 44819e5..0ae6eb8 100644
--- a/stm50flw0x0x.c
+++ b/stm50flw0x0x.c
@@ -31,15 +31,6 @@
 #include "flash.h"
 #include "flashchips.h"
 
-void protect_stm50flw0x0x(chipaddr bios)
-{
-	chip_writeb(0xAA, bios + 0x5555);
-	chip_writeb(0x55, bios + 0x2AAA);
-	chip_writeb(0xA0, bios + 0x5555);
-
-	programmer_delay(200);
-}
-
 int probe_stm50flw0x0x(struct flashchip *flash)
 {
 	int result = probe_jedec(flash);
@@ -189,7 +180,6 @@ int erase_stm50flw0x0x(struct flashchip *flash)
 	int i;
 	int total_size = flash->total_size * 1024;
 	int page_size = flash->page_size;
-	chipaddr bios = flash->virtual_memory;
 
 	printf("Erasing page:\n");
 	for (i = 0; i < total_size / page_size; i++) {
@@ -206,7 +196,6 @@ int erase_stm50flw0x0x(struct flashchip *flash)
 		}
 	}
 	printf("\n");
-	protect_stm50flw0x0x(bios);
 
 	return 0;
 }
@@ -250,7 +239,6 @@ int write_stm50flw0x0x(struct flashchip *flash, uint8_t * buf)
 					bios + i * page_size, page_size);
 	}
 	printf("\n");
-	protect_stm50flw0x0x(bios);
 	free(tmpbuf);
 
 	return rc;