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,
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));
return ERROR_JTAG_INIT_FAILED;
}
- pads_base = mmap(NULL, sysconf(_SC_PAGE_SIZE), PROT_READ | PROT_WRITE,
+ /* 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;
+ if (pads_base == MAP_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);
- /* set 4mA drive strength, slew rate limited, hysteresis on */
- initial_drive_strength_etc = pads_base[BCM2835_PADS_GPIO_0_27_OFFSET] & 0x1f;
- pads_base[BCM2835_PADS_GPIO_0_27_OFFSET] = 0x5a000008 + 1;
+ 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.
restore_gpio(ADAPTER_GPIO_IDX_SRST);
restore_gpio(ADAPTER_GPIO_IDX_LED);
- /* Restore drive strength. MSB is password ("5A") */
- pads_base[BCM2835_PADS_GPIO_0_27_OFFSET] = 0x5A000000 | initial_drive_strength_etc;
+ 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;