flash/nor/stm32lx: fixed writes at high adapter speeds

The busy flag must be polled after each half-page write.
At low clock speeds, no issue is observed when the poll
is omitted, because the writes complete before the next
write begins. But at high clock speeds the subsequent
writes would overlap and cause the operation to fail.

The status polls are done on the target for efficiency,
since the half-pages are very small.

Change-Id: Ia1e9b4a6a71930549b3d84a902744ce6e596301b
Signed-off-by: Jimmy <nhminus@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/5598
Tested-by: jenkins
Reviewed-by: Jelle De Vleeschouwer
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-by: Andrzej Sierżęga <asier70@gmail.com>

2 files changed, 37 insertions, 19 deletions

diff --git a/contrib/loaders/flash/stm32/stm32lx.S b/contrib/loaders/flash/stm32/stm32lx.S
index bcae7a4..7cfe485 100644
--- a/contrib/loaders/flash/stm32/stm32lx.S
+++ b/contrib/loaders/flash/stm32/stm32lx.S
@@ -20,44 +20,61 @@
  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  *   GNU General Public License for more details.                          *
- *                                                                         *
- *   You should have received a copy of the GNU General Public License     *
- *   along with this program; if not, write to the                         *
- *   Free Software Foundation, Inc.,                                       *
- *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.           *
  ***************************************************************************/
 
-
 	.text
 	.syntax unified
 	.cpu cortex-m0
 	.thumb
 
 /*
+Parameters
 	r0 - destination address
 	r1 - source address
-	r2 - count
+	r2 - half pages
+	r3 - bytes per half page
+	r4 - flash base
+Variables
+	r0 - destination write pointer
+	r1 - source read pointer
+	r2 - source limit address
+	r3 - bytes per half page
+	r4 - flash base
+	r5 - pages left in current half page
+	r6 - temporary r/w
 */
 
+/* offsets of registers from flash reg base */
+#define STM32_FLASH_SR_OFFSET 0x18
+
 	.thumb_func
 	.global _start
 _start:
-	// r2 = source + count * 4
-	lsls	r2, r2, #2
-	adds	r2, r1, r2
+	// r2 = source + half pages * bytes per half page
+	muls r2, r2, r3
+	add r2, r1, r2
 	// Go to compare
-	b	test_done
+	b test_done
+write_half_page:
+	// initialize pages left in current half page
+	mov r5, r3
 write_word:
 	// load word from address in r1 and increase r1 by 4
-	ldmia r1!, {r3}
+	ldmia r1!, {r6}
 	// store word to address in r0 and increase r0 by 4
-	stmia r0!, {r3}
+	stmia r0!, {r6}
+	// check for end of half page
+	subs r5, r5, #4
+	bne write_word
+wait_busy:
+	// read status register into r6, loop while bottom bit is set
+	ldr r6, [r4, #STM32_FLASH_SR_OFFSET]
+	lsls r6, r6, #31
+	bne wait_busy
 test_done:
-	// compare r1 and r2
+	// compare r1 and r2, loop if not equal
 	cmp	r1, r2
-	// loop if not equal
-	bne	write_word
+	bne	write_half_page
 
 	// Set breakpoint to exit
-	bkpt	#0x00
-
+	bkpt #0x00
diff --git a/contrib/loaders/flash/stm32/stm32lx.inc b/contrib/loaders/flash/stm32/stm32lx.inc
index eaaf184..668de27 100644
--- a/contrib/loaders/flash/stm32/stm32lx.inc
+++ b/contrib/loaders/flash/stm32/stm32lx.inc
@@ -1,2 +1,3 @@
 /* Autogenerated with ../../../../src/helper/bin2char.sh */
-0x92,0x00,0x8a,0x18,0x01,0xe0,0x08,0xc9,0x08,0xc0,0x91,0x42,0xfb,0xd1,0x00,0xbe,
+0x5a,0x43,0x0a,0x44,0x07,0xe0,0x1d,0x46,0x40,0xc9,0x40,0xc0,0x04,0x3d,0xfb,0xd1,
+0xa6,0x69,0xf6,0x07,0xfc,0xd1,0x91,0x42,0xf5,0xd1,0x00,0xbe,