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jtag/drivers/bcm2835gpio: don't touch pad setting on /dev/gpiomem 

The pads were configured at a wrong memory address
if /dev/gpiomem was mapped.

The pad setting registers are not accessible in mapped /dev/gpiomem,
disable the pads setting if the driver doesn't open /dev/mem.

While on it, do not fail the driver initialization if pad mapping fails
- just emit a warning and work with unchanged pad setting.

Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Change-Id: I0bce76cade8f7efd75efd9087a7d9ba6511a6239
Reviewed-on: https://review.openocd.org/c/openocd/+/7684
Tested-by: jenkins
Reviewed-by: Jonathan Bell <jonathan@raspberrypi.com>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
This commit is contained in:
Tomas Vanek 2022-11-15 09:47:43 +01:00
parent 30b0e9af8d
commit c164906420
2 changed files with 28 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
doc/openocd.texi
View File

@ -3292,8 +3292,12 @@ configuration on exit.
GPIO numbers >= 32 can't be used for performance reasons. GPIO configuration is
handled by the generic command @ref{adapter gpio, @command{adapter gpio}}.
/dev/gpiomem is preferred for GPIO mapping with fallback to /dev/mem.
If /dev/mem is used GPIO 0-27 pads are set to the limited
slew rate and drive strength is reduced to 4 mA (2 mA on RPi 4).
See @file{interface/raspberrypi-native.cfg} for a sample config and
pinout.
@file{interface/raspberrypi-gpio-connector.cfg} for pinout.
@deffn {Config Command} {bcm2835gpio speed_coeffs} @var{speed_coeff} @var{speed_offset}
Set SPEED_COEFF and SPEED_OFFSET for delay calculations. If unspecified,

20
src/jtag/drivers/bcm2835gpio.c
View File

@ -409,10 +409,13 @@ static int bcm2835gpio_init(void)
return ERROR_JTAG_INIT_FAILED;
}
bool pad_mapping_possible = false;
dev_mem_fd = open("/dev/gpiomem", O_RDWR | O_SYNC);
if (dev_mem_fd < 0) {
LOG_DEBUG("Cannot open /dev/gpiomem, fallback to /dev/mem");
dev_mem_fd = open("/dev/mem", O_RDWR | O_SYNC);
pad_mapping_possible = true;
}
if (dev_mem_fd < 0) {
LOG_ERROR("open: %s", strerror(errno));
@ -428,21 +431,28 @@ static int bcm2835gpio_init(void)
return ERROR_JTAG_INIT_FAILED;
}
/* TODO: move pads config to a separate utility */
if (pad_mapping_possible) {
pads_base = mmap(NULL, sysconf(_SC_PAGE_SIZE), PROT_READ | PROT_WRITE,
MAP_SHARED, dev_mem_fd, BCM2835_PADS_GPIO_0_27);
if (pads_base == MAP_FAILED) {
LOG_ERROR("mmap: %s", strerror(errno));
bcm2835gpio_munmap();
close(dev_mem_fd);
return ERROR_JTAG_INIT_FAILED;
LOG_ERROR("mmap pads: %s", strerror(errno));
LOG_WARNING("Continuing with unchanged GPIO pad settings (drive strength and slew rate)");
}
} else {
pads_base = MAP_FAILED;
}
close(dev_mem_fd);
if (pads_base != MAP_FAILED) {
/* set 4mA drive strength, slew rate limited, hysteresis on */
initial_drive_strength_etc = pads_base[BCM2835_PADS_GPIO_0_27_OFFSET] & 0x1f;
LOG_INFO("initial pads conf %08x", pads_base[BCM2835_PADS_GPIO_0_27_OFFSET]);
pads_base[BCM2835_PADS_GPIO_0_27_OFFSET] = 0x5a000008 + 1;
LOG_INFO("pads conf set to %08x", pads_base[BCM2835_PADS_GPIO_0_27_OFFSET]);
}
/* Configure JTAG/SWD signals. Default directions and initial states are handled
* by adapter.c and "adapter gpio" command.
@ -513,8 +523,10 @@ static int bcm2835gpio_quit(void)
restore_gpio(ADAPTER_GPIO_IDX_SRST);
restore_gpio(ADAPTER_GPIO_IDX_LED);
if (pads_base != MAP_FAILED) {
/* Restore drive strength. MSB is password ("5A") */
pads_base[BCM2835_PADS_GPIO_0_27_OFFSET] = 0x5A000000 | initial_drive_strength_etc;
}
bcm2835gpio_munmap();
return ERROR_OK;