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at91samd: fix protect, add EEPROM and boot commands

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There were two problems with the _protect() feature:
1. The address written was off by a factor of two because the address
register takes 16-bit rather than 8-bit addresses.  As a result the
wrong sectors were (un)protected with the protect command.  This has
been fixed.
2. The protection settings issued via the lock or unlock region commands
don't persist after reset.  Making them persist requires modifying the
LOCK bits in the User Row using the infrastructure described below.

The Atmel SAMD2x MCUs provide a User Row (the size of which is one
page).  This contains a few settings that users may wish to modify from
the debugger, especially during production.  This change adds commands
to inspect and set:
- EEPROM size, the size in bytes of the emulated EEPROM region of the
  Flash.
- Bootloader size, the size in bytes of the protected "boot" section of
  the Flash.

This is done by a careful read-modify-write of the special User Row
page, avoiding erasing when possible and disallowing the changing of
documented reserved bits.  The Atmel SAMD20 datasheet was used for bit
positions and descriptions, size tables, etc. and testing was done on a
SAMD20 Xplained Pro board.

It's technically possible to store arbitrary user data (ex: serial
numbers, MAC addresses, etc) in the remaining portion of the User Row
page (that is, beyond the first 64 bits of it).  The infrastructure used
by the eeprom and bootloader commands can be used to access this as
well, and this seems safer than exposing the User Row as a normal Flash
sector that openocd understands due to the delicate nature of some of
the data stored there.

Change-Id: I29ca1bdbdc7884bc0ba0ad18af1b6bab78c7ad38
Signed-off-by: Andrey Yurovsky <yurovsky@gmail.com>
Reviewed-on: http://openocd.zylin.com/2326
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>
This commit is contained in:
Andrey Yurovsky
2014-09-30 13:02:49 -07:00
committed by Spencer Oliver
parent 592d0d514d
commit db4b2c2536
2 changed files with 342 additions and 39 deletions
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28
doc/openocd.texi
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@@ -5045,6 +5045,34 @@ at91samd set-security enable
@end example
@end deffn
@deffn Command {at91samd eeprom}
Shows or sets the EEPROM emulation size configuration, stored in the User Row
of the Flash. When setting, the EEPROM size must be specified in bytes and it
must be one of the permitted sizes according to the datasheet. Settings are
written immediately but only take effect on MCU reset. EEPROM emulation
requires additional firmware support and the minumum EEPROM size may not be
the same as the minimum that the hardware supports. Set the EEPROM size to 0
in order to disable this feature.
@example
at91samd eeprom
at91samd eeprom 1024
@end example
@end deffn
@deffn Command {at91samd bootloader}
Shows or sets the bootloader size configuration, stored in the User Row of the
Flash. This is called the BOOTPROT region. When setting, the bootloader size
must be specified in bytes and it must be one of the permitted sizes according
to the datasheet. Settings are written immediately but only take effect on
MCU reset. Setting the bootloader size to 0 disables bootloader protection.
@example
at91samd bootloader
at91samd bootloader 16384
@end example
@end deffn
@end deffn
@anchor{at91sam3}