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flash: add stm32lx loader Hard Fault workaround 

An issue has been seen with the stm32lx flash driver that if a
power cycle/reset is applied after a erase, any ram loader will Hard Fault
on execution.

A similar issue is mentioned in the errata for the device.
Two solution's seem to workaround this issue:
1, Handle the exception, this means adding exception vectors to the loader
   and changing the exception address using nvic vtor register.
2. falling back to using slower direct page writes - approx 50% slower.

Using solution 1 would mean restrictions are placed on the loader location.
Solution 2 was chosen mainly as it was simpler too implement.

Change-Id: I429f06b5a3e3b1d8de90071a88a7df11fc9b46a7
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/1010
Tested-by: jenkins
This commit is contained in:
Spencer Oliver 2013-01-04 11:46:00 +00:00
parent 6efcd943b2
commit d631b2e5ac
1 changed files with 53 additions and 0 deletions
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53
src/flash/nor/stm32lx.c
View File

@ -32,6 +32,7 @@
#include <helper/binarybuffer.h>
#include <target/algorithm.h>
#include <target/armv7m.h>
#include <target/cortex_m.h>
/* stm32lx flash register locations */
@ -299,6 +300,18 @@ static int stm32lx_write_half_pages(struct flash_bank *bank, uint8_t *buffer,
return retval;
}
struct armv7m_common *armv7m = target_to_armv7m(target);
if (armv7m == NULL) {
/* something is very wrong if armv7m is NULL */
LOG_ERROR("unable to get armv7m target");
return retval;
}
/* save any DEMCR flags and configure target to catch any Hard Faults */
uint32_t demcr_save = armv7m->demcr;
armv7m->demcr = VC_HARDERR;
/* Loop while there are bytes to write */
while (count > 0) {
uint32_t this_count;
@ -324,6 +337,10 @@ static int stm32lx_write_half_pages(struct flash_bank *bank, uint8_t *buffer,
if (retval != ERROR_OK)
break;
/* check for Hard Fault */
if (armv7m->exception_number == 3)
break;
/* 6: Wait while busy */
retval = stm32lx_wait_until_bsy_clear(bank);
if (retval != ERROR_OK)
@ -334,6 +351,42 @@ static int stm32lx_write_half_pages(struct flash_bank *bank, uint8_t *buffer,
count -= this_count;
}
/* restore previous flags */
armv7m->demcr = demcr_save;
if (armv7m->exception_number == 3) {
/* the stm32l15x devices seem to have an issue when blank.
* if a ram loader is executed on a blank device it will
* Hard Fault, this issue does not happen for a already programmed device.
* A related issue is described in the stm32l151xx errata (Doc ID 17721 Rev 6 - 2.1.3).
* The workaround of handling the Hard Fault exception does work, but makes the
* loader more complicated, as a compromise we manually write the pages, programming time
* is reduced by 50% using this slower method.
*/
LOG_WARNING("couldn't use loader, falling back to page memory writes");
while (count > 0) {
uint32_t this_count;
this_count = (count > 128) ? 128 : count;
/* Write the next half pages */
retval = target_write_buffer(target, address, this_count, buffer);
if (retval != ERROR_OK)
break;
/* Wait while busy */
retval = stm32lx_wait_until_bsy_clear(bank);
if (retval != ERROR_OK)
break;
buffer += this_count;
address += this_count;
count -= this_count;
}
}
if (retval == ERROR_OK)
retval = stm32lx_lock_program_memory(bank);