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driver/linuxgpiod: add support for opendrain srst 

Some MCUs (e.g. the STM32F3) directly expose the internal reset line to
an external pin. When this signal is driven by a push/pull line, it can
actually be inhibited by the external driver. This results in a setup
where the MCU cannot reset itself, for example, by a watchdog timeout or
a sysreset request. To fix this condition, support for open drain output
on the SRST line is required.

Note that because `reset_config srst_open_drain` is the default, all
users of this adapter will switch over to an open drain output unless
explicitly configured otherwise.

Signed-off-by: Alex Crawford <openocd@code.acrawford.com>
Change-Id: I89b39b03aa03f826ed3c45793412780448940bcc
Reviewed-on: https://review.openocd.org/c/openocd/+/6559
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
This commit is contained in:
Alex Crawford 2021-09-16 10:00:25 -07:00 committed by Antonio Borneo
parent 5765a0ce14
commit 2f424b7eb7
1 changed files with 24 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
src/jtag/drivers/linuxgpiod.c
View File

@ -278,7 +278,7 @@ static int linuxgpiod_quit(void)
return ERROR_OK;
}
static struct gpiod_line *helper_get_input_line(const char *label, unsigned int offset)
static struct gpiod_line *helper_get_line(const char *label, unsigned int offset, int val, int dir, int flags)
{
struct gpiod_line *line;
int retval;
@ -289,33 +289,34 @@ static struct gpiod_line *helper_get_input_line(const char *label, unsigned int
return NULL;
}
retval = gpiod_line_request_input(line, "OpenOCD");
struct gpiod_line_request_config config = {
.consumer = "OpenOCD",
.request_type = dir,
.flags = flags,
};
retval = gpiod_line_request(line, &config, val);
if (retval < 0) {
LOG_ERROR("Error request_input line %s", label);
LOG_ERROR("Error requesting gpio line %s", label);
return NULL;
}
return line;
}
static struct gpiod_line *helper_get_input_line(const char *label, unsigned int offset)
{
return helper_get_line(label, offset, 0, GPIOD_LINE_REQUEST_DIRECTION_INPUT, 0);
}
static struct gpiod_line *helper_get_output_line(const char *label, unsigned int offset, int val)
{
struct gpiod_line *line;
int retval;
return helper_get_line(label, offset, val, GPIOD_LINE_REQUEST_DIRECTION_OUTPUT, 0);
}
line = gpiod_chip_get_line(gpiod_chip, offset);
if (!line) {
LOG_ERROR("Error get line %s", label);
return NULL;
}
retval = gpiod_line_request_output(line, "OpenOCD", val);
if (retval < 0) {
LOG_ERROR("Error request_output line %s", label);
return NULL;
}
return line;
static struct gpiod_line *helper_get_open_drain_output_line(const char *label, unsigned int offset, int val)
{
return helper_get_line(label, offset, val, GPIOD_LINE_REQUEST_DIRECTION_OUTPUT, GPIOD_LINE_REQUEST_FLAG_OPEN_DRAIN);
}
static int linuxgpiod_init(void)
@ -381,7 +382,11 @@ static int linuxgpiod_init(void)
}
if (is_gpio_valid(srst_gpio)) {
gpiod_srst = helper_get_output_line("srst", srst_gpio, 1);
if (jtag_get_reset_config() & RESET_SRST_PUSH_PULL)
gpiod_srst = helper_get_output_line("srst", srst_gpio, 1);
else
gpiod_srst = helper_get_open_drain_output_line("srst", srst_gpio, 1);
if (!gpiod_srst)
goto out_error;
}