flash/nor/at91samd: Use 32-bit register writes for ST-Link compat

ST-Link v2 dongles can be used with many cortex-m parts, but they have
one limitation -- they can only perform 8-bit and 32-bit writes to the
target. 16-bit writes are done using a pair of 8-bit writes. While not
usually an issue, in the case of the at91samd flash driver, the 16-bit
'command' register must have both halves written in the same
operation.

Fortunately, this register has two pad bytes above it in the address
space, making it safe to always access with 32-bit operations.

Change-Id: I44b0db9406982a8db5818c0533d3101618741db2
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/7234
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
This commit is contained in:
Keith Packard 2022-09-28 14:02:52 -07:00 committed by Antonio Borneo
parent 0cedf10f8f
commit af75d70dc5
1 changed files with 2 additions and 1 deletions

View File

@ -543,7 +543,8 @@ static int samd_issue_nvmctrl_command(struct target *target, uint16_t cmd)
} }
/* Issue the NVM command */ /* Issue the NVM command */
res = target_write_u16(target, /* 32-bit write is used to ensure atomic operation on ST-Link */
res = target_write_u32(target,
SAMD_NVMCTRL + SAMD_NVMCTRL_CTRLA, SAMD_NVM_CMD(cmd)); SAMD_NVMCTRL + SAMD_NVMCTRL_CTRLA, SAMD_NVM_CMD(cmd));
if (res != ERROR_OK) if (res != ERROR_OK)
return res; return res;