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chip/stm32/flash-f: Clear option byte write enable/erase operation when done

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Before
72afc55bd9 "stm32: cleanup flash-f by using constant from register.h"
lock() function would simply do:
STM32_FLASH_CR = FLASH_CR_LOCK;

which would clear all other bits in STM32_FLASH_CR, including
FLASH_CR_OPTER and FLASH_CR_OPTWRE.

This allow preserve_optb to work, as it does:
 1. erase_optb
   a. unlock()
   b. Set FLASH_CR_OPTER
   c. lock() (clears FLASH_CR_OPTER!)
 2. write_optb
   a. unlock()
   b. Set FLASH_CR_OPTPG
   c. Write option byte
   d. Clear FLASH_CR_OPTPG
   e. lock()

After the patch, we now have:
STM32_FLASH_CR |= FLASH_CR_LOCK;
which seems more correct. However, 1.c. does not clear FLASH_CR_OPTER,
and 2.b. ends up with both FLASH_CR_OPTPG and FLASH_CR_OPTER set,
and the programming operation does not do anything.

This patches does 3 things:
 - Rename FLASH_CR_OPTSTRT to FLASH_CR_OPTER, as that's the correct
   register name for STM32F0 and STM32F3.
 - Fix the above by clearing FLASH_CR_OPTER in erase_optb
 - Also clear FLASH_CR_OPTWRE in lock(). Not strictly necessary,
   but this seems to be the right thing to do.

BRANCH=none
BUG=chromium:739608
TEST=On hammer, type flashwp true; reboot; flashwp all; reboot
     flashinfo => All flash is protected

Change-Id: Ic276545ae3c0bdb685c7b117a7f896ec341731bb
Reviewed-on: https://chromium-review.googlesource.com/562839
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Wei-Ning Huang <wnhuang@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
This commit is contained in:
Nicolas Boichat
2017-07-07 09:03:28 +08:00
committed by chrome-bot
parent bdd39d51a3
commit 241e7e3a01
2 changed files with 9 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
chip/stm32/flash-f.c
View File

@@ -82,6 +82,10 @@ static int unlock(int locks)
static void lock(void)
{
#if defined(CHIP_FAMILY_STM32F0) || defined(CHIP_FAMILY_STM32F3)
/* FLASH_CR_OPTWRE was set by writing the keys in unlock(). */
STM32_FLASH_CR &= ~FLASH_CR_OPTWRE;
#endif
STM32_FLASH_CR |= FLASH_CR_LOCK;
}
@@ -147,10 +151,13 @@ static int erase_optb(void)
return rv;
/* Must be set in 2 separate lines. */
STM32_FLASH_CR |= FLASH_CR_OPTSTRT;
STM32_FLASH_CR |= FLASH_CR_OPTER;
STM32_FLASH_CR |= FLASH_CR_STRT;
rv = wait_busy();
STM32_FLASH_CR &= ~FLASH_CR_OPTER;
if (rv)
return rv;
lock();

2
chip/stm32/registers.h
View File

@@ -1342,7 +1342,7 @@ typedef volatile struct stm32_spi_regs stm32_spi_regs_t;
#define FLASH_CR_PG (1 << 0)
#define FLASH_CR_PER (1 << 1)
#define FLASH_CR_OPTPG (1 << 4)
#define FLASH_CR_OPTSTRT (1 << 5)
#define FLASH_CR_OPTER (1 << 5)
#define FLASH_CR_STRT (1 << 6)
#define FLASH_CR_LOCK (1 << 7)
#define FLASH_CR_OPTWRE (1 << 9)