From: Tomas Vanek Date: Sat, 13 May 2023 04:39:48 +0000 (+0200) Subject: jtag/drivers/bcm2835gpio: add peripheral_mem_dev config command X-Git-Url: https://review.openocd.org/gitweb?p=openocd.git;a=commitdiff_plain;h=5c46a5de49f5dd14227b9444a5815eaaadd7ceb4;hp=b41b368255d53d9561851900eeeba38b12720a82 jtag/drivers/bcm2835gpio: add peripheral_mem_dev config command The bcm2835gpio driver preferred /dev/gpiomem for access to memory mapped GPIO control and used /dev/mem as a fallback only if it couldn't open /dev/gpiomem. /dev/mem usually requires elevated rights or specific capabilities of the opening process, so the fallback failed anyway. Although /dev/gpiomem is the strongly preferred option with respect to security, there could be also use cases which require /dev/mem even if /dev/gpiomem is available (e.g. changing the GPIO pad settings is necessary or testing/debugging OpenOCD). It was difficult to handle such cases because they required to block globally the system device /dev/gpiomem (remove, rename or chmod). Drop the fallback feature and select the memory device by 'bcm2835gpio peripheral_mem_dev' configuration command. Use /dev/gpiomem as a default. Signed-off-by: Tomas Vanek Change-Id: I60e427bda795d7a13d55d61443590dd31d694832 Reviewed-on: https://review.openocd.org/c/openocd/+/7350 Tested-by: jenkins Reviewed-by: Jonathan Bell --- diff --git a/doc/openocd.texi b/doc/openocd.texi index f27e17ceac..d0bc3f9f50 100644 --- a/doc/openocd.texi +++ b/doc/openocd.texi @@ -3292,10 +3292,6 @@ 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 @file{interface/raspberrypi-gpio-connector.cfg} for pinout. @@ -3304,8 +3300,25 @@ Set SPEED_COEFF and SPEED_OFFSET for delay calculations. If unspecified, speed_coeff defaults to 113714, and speed_offset defaults to 28. @end deffn +@deffn {Config Command} {bcm2835gpio peripheral_mem_dev} @var{device} +Set the device path for access to the memory mapped GPIO control registers. +Uses @file{/dev/gpiomem} by default, this is also the preferred option with +respect to system security. +If overridden to @file{/dev/mem}: +@itemize @minus +@item OpenOCD needs @code{cap_sys_rawio} or run as root to open @file{/dev/mem}. +Please be aware of security issues imposed by running OpenOCD with +elevated user rights and by @file{/dev/mem} itself. +@item correct @command{peripheral_base} must be configured. +@item GPIO 0-27 pads are set to the limited slew rate +and drive strength is reduced to 4 mA (2 mA on RPi 4). +@end itemize + +@end deffn + @deffn {Config Command} {bcm2835gpio peripheral_base} @var{base} -Set the peripheral base register address to access GPIOs. For the RPi1, use +Set the peripheral base register address to access GPIOs. +Ignored if @file{/dev/gpiomem} is used. For the RPi1, use 0x20000000. For RPi2 and RPi3, use 0x3F000000. For RPi4, use 0xFE000000. A full list can be found in the @uref{https://www.raspberrypi.org/documentation/hardware/raspberrypi/peripheral_addresses.md, official guide}. diff --git a/src/jtag/drivers/bcm2835gpio.c b/src/jtag/drivers/bcm2835gpio.c index c72386024f..39e4af3657 100644 --- a/src/jtag/drivers/bcm2835gpio.c +++ b/src/jtag/drivers/bcm2835gpio.c @@ -19,6 +19,7 @@ #include +static char *bcm2835_peri_mem_dev; static off_t bcm2835_peri_base = 0x20000000; #define BCM2835_GPIO_BASE (bcm2835_peri_base + 0x200000) /* GPIO controller */ @@ -57,6 +58,14 @@ static struct initial_gpio_state { } initial_gpio_state[ADAPTER_GPIO_IDX_NUM]; static uint32_t initial_drive_strength_etc; +static inline const char *bcm2835_get_mem_dev(void) +{ + if (bcm2835_peri_mem_dev) + return bcm2835_peri_mem_dev; + + return "/dev/gpiomem"; +} + static inline void bcm2835_gpio_synchronize(void) { /* Ensure that previous writes to GPIO registers are flushed out of @@ -300,6 +309,18 @@ COMMAND_HANDLER(bcm2835gpio_handle_speed_coeffs) return ERROR_OK; } +COMMAND_HANDLER(bcm2835gpio_handle_peripheral_mem_dev) +{ + if (CMD_ARGC == 1) { + free(bcm2835_peri_mem_dev); + bcm2835_peri_mem_dev = strdup(CMD_ARGV[0]); + } + + command_print(CMD, "BCM2835 GPIO: peripheral_mem_dev = %s", + bcm2835_get_mem_dev()); + return ERROR_OK; +} + COMMAND_HANDLER(bcm2835gpio_handle_peripheral_base) { uint64_t tmp_base; @@ -322,6 +343,13 @@ static const struct command_registration bcm2835gpio_subcommand_handlers[] = { .help = "SPEED_COEFF and SPEED_OFFSET for delay calculations.", .usage = "[SPEED_COEFF SPEED_OFFSET]", }, + { + .name = "peripheral_mem_dev", + .handler = &bcm2835gpio_handle_peripheral_mem_dev, + .mode = COMMAND_CONFIG, + .help = "device to map memory mapped GPIOs from.", + .usage = "[device]", + }, { .name = "peripheral_base", .handler = &bcm2835gpio_handle_peripheral_base, @@ -413,16 +441,16 @@ static int bcm2835gpio_init(void) return ERROR_JTAG_INIT_FAILED; } - bool pad_mapping_possible = false; + bool is_gpiomem = strcmp(bcm2835_get_mem_dev(), "/dev/gpiomem") == 0; + bool pad_mapping_possible = !is_gpiomem; - 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; - } + dev_mem_fd = open(bcm2835_get_mem_dev(), O_RDWR | O_SYNC); if (dev_mem_fd < 0) { - LOG_ERROR("open: %s", strerror(errno)); + LOG_ERROR("open %s: %s", bcm2835_get_mem_dev(), strerror(errno)); + /* TODO: add /dev/mem specific doc and refer to it + * if (!is_gpiomem && (errno == EACCES || errno == EPERM)) + * LOG_INFO("Consult the user's guide chapter 4.? how to set permissions and capabilities"); + */ return ERROR_JTAG_INIT_FAILED; } @@ -532,6 +560,7 @@ static int bcm2835gpio_quit(void) pads_base[BCM2835_PADS_GPIO_0_27_OFFSET] = 0x5A000000 | initial_drive_strength_etc; } bcm2835gpio_munmap(); + free(bcm2835_peri_mem_dev); return ERROR_OK; }