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- /***************************************************************************
- * Copyright (C) 2012 by Creative Product Design, marc @ cpdesign.com.au *
- * *
- * This program is free software; you can redistribute it and/or modify *
- * it under the terms of the GNU General Public License as published by *
- * the Free Software Foundation; either version 2 of the License, or *
- * (at your option) any later version. *
- * *
- * This program is distributed in the hope that it will be useful, *
- * but WITHOUT ANY WARRANTY; without even the implied warranty of *
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
- * GNU General Public License for more details. *
- * *
- * You should have received a copy of the GNU General Public License *
- * along with this program; if not, write to the *
- * Free Software Foundation, Inc., *
- * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
- ***************************************************************************/
- /**
- * @file
- * This driver implements a bitbang jtag interface using gpio lines via
- * sysfs.
- * The aim of this driver implementation is use system GPIOs but avoid the
- * need for a additional kernel driver.
- * (Note memory mapped IO is another option, however it doesn't mix well with
- * the kernel gpiolib driver - which makes sense I guess.)
- *
- * A gpio is required for tck, tms, tdi and tdo. One or both of srst and trst
- * must be also be specified. The required jtag gpios are specified via the
- * sysfsgpio_jtag_nums command or the relevant sysfsgpio_XXX_num commang.
- * The srst and trst gpios are set via the sysfsgpio_srst_num and
- * sysfsgpio_trst_num respectively. GPIO numbering follows the kernel
- * convention of starting from 0.
- *
- * The gpios should not be in use by another entity, and must not be requested
- * by a kernel driver without also being exported by it (otherwise they can't
- * be exported by sysfs).
- *
- * The sysfs gpio interface can only manipulate one gpio at a time, so the
- * bitbang write handler remembers the last state for tck, tms, tdi to avoid
- * superfluous writes.
- * For speed the sysfs "value" entry is opened at init and held open.
- * This results in considerable gains over open-write-close (45s vs 900s)
- *
- * Further work could address:
- * -srst and trst open drain/ push pull
- * -configurable active high/low for srst & trst
- */
- #ifdef HAVE_CONFIG_H
- #include "config.h"
- #endif
-
- #include <jtag/interface.h>
- #include "bitbang.h"
-
- /*
- * Helper func to determine if gpio number valid
- *
- * Assume here that there will be less than 1000 gpios on a system
- */
- static int is_gpio_valid(int gpio)
- {
- return gpio >= 0 && gpio < 1000;
- }
-
- /*
- * Helper func to open, write to and close a file
- * name and valstr must be null terminated.
- *
- * Returns negative on failure.
- */
- static int open_write_close(const char *name, const char *valstr)
- {
- int ret;
- int fd = open(name, O_WRONLY);
- if (fd < 0)
- return fd;
-
- ret = write(fd, valstr, strlen(valstr));
- close(fd);
-
- return ret;
- }
-
- /*
- * Helper func to unexport gpio from sysfs
- */
- static void unexport_sysfs_gpio(int gpio)
- {
- char gpiostr[4];
-
- if (!is_gpio_valid(gpio))
- return;
-
- snprintf(gpiostr, sizeof(gpiostr), "%d", gpio);
- if (open_write_close("/sys/class/gpio/unexport", gpiostr) < 0)
- LOG_ERROR("Couldn't unexport gpio %d", gpio);
-
- return;
- }
-
- /*
- * Exports and sets up direction for gpio.
- * If the gpio is an output, it is initialized according to init_high,
- * otherwise it is ignored.
- *
- * If the gpio is already exported we just show a warning and continue; if
- * openocd happened to crash (or was killed by user) then the gpios will not
- * have been cleaned up.
- */
- static int setup_sysfs_gpio(int gpio, int is_output, int init_high)
- {
- char buf[40];
- char gpiostr[4];
- int ret;
-
- if (!is_gpio_valid(gpio))
- return ERROR_OK;
-
- snprintf(gpiostr, sizeof(gpiostr), "%d", gpio);
- ret = open_write_close("/sys/class/gpio/export", gpiostr);
- if (ret < 0) {
- if (errno == EBUSY) {
- LOG_WARNING("gpio %d is already exported", gpio);
- } else {
- LOG_ERROR("Couldn't export gpio %d", gpio);
- perror("sysfsgpio: ");
- return ERROR_FAIL;
- }
- }
-
- snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", gpio);
- ret = open_write_close(buf, is_output ? (init_high ? "high" : "low") : "in");
- if (ret < 0) {
- LOG_ERROR("Couldn't set direction for gpio %d", gpio);
- perror("sysfsgpio: ");
- unexport_sysfs_gpio(gpio);
- return ERROR_FAIL;
- }
-
- snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/value", gpio);
- if (is_output)
- ret = open(buf, O_WRONLY | O_NONBLOCK | O_SYNC);
- else
- ret = open(buf, O_RDONLY | O_NONBLOCK | O_SYNC);
-
- if (ret < 0)
- unexport_sysfs_gpio(gpio);
-
- return ret;
- }
-
- /*
- * file descriptors for /sys/class/gpio/gpioXX/value
- * Set up during init.
- */
- static int tck_fd = -1;
- static int tms_fd = -1;
- static int tdi_fd = -1;
- static int tdo_fd = -1;
- static int trst_fd = -1;
- static int srst_fd = -1;
-
- /*
- * Bitbang interface read of TDO
- *
- * The sysfs value will read back either '0' or '1'. The trick here is to call
- * lseek to bypass buffering in the sysfs kernel driver.
- */
- static int sysfsgpio_read(void)
- {
- char buf[1];
-
- /* important to seek to signal sysfs of new read */
- lseek(tdo_fd, 0, SEEK_SET);
- int ret = read(tdo_fd, &buf, sizeof(buf));
-
- if (ret < 0) {
- LOG_WARNING("reading tdo failed");
- return 0;
- }
-
- return buf[0] == '1';
- }
-
- /*
- * Bitbang interface write of TCK, TMS, TDI
- *
- * Seeing as this is the only function where the outputs are changed,
- * we can cache the old value to avoid needlessly writing it.
- */
- static void sysfsgpio_write(int tck, int tms, int tdi)
- {
- const char one[] = "1";
- const char zero[] = "0";
-
- static int last_tck;
- static int last_tms;
- static int last_tdi;
-
- static int first_time;
- size_t bytes_written;
-
- if (!first_time) {
- last_tck = !tck;
- last_tms = !tms;
- last_tdi = !tdi;
- first_time = 1;
- }
-
- if (tdi != last_tdi) {
- bytes_written = write(tdi_fd, tdi ? &one : &zero, 1);
- if (bytes_written != 1)
- LOG_WARNING("writing tdi failed");
- }
-
- if (tms != last_tms) {
- bytes_written = write(tms_fd, tms ? &one : &zero, 1);
- if (bytes_written != 1)
- LOG_WARNING("writing tms failed");
- }
-
- /* write clk last */
- if (tck != last_tck) {
- bytes_written = write(tck_fd, tck ? &one : &zero, 1);
- if (bytes_written != 1)
- LOG_WARNING("writing tck failed");
- }
-
- last_tdi = tdi;
- last_tms = tms;
- last_tck = tck;
- }
-
- /*
- * Bitbang interface to manipulate reset lines SRST and TRST
- *
- * (1) assert or (0) deassert reset lines
- */
- static void sysfsgpio_reset(int trst, int srst)
- {
- const char one[] = "1";
- const char zero[] = "0";
- size_t bytes_written;
-
- /* assume active low */
- if (srst_fd >= 0) {
- bytes_written = write(srst_fd, srst ? &zero : &one, 1);
- if (bytes_written != 1)
- LOG_WARNING("writing srst failed");
- }
-
- /* assume active low */
- if (trst_fd >= 0) {
- bytes_written = write(trst_fd, trst ? &zero : &one, 1);
- if (bytes_written != 1)
- LOG_WARNING("writing trst failed");
- }
- }
-
- /* gpio numbers for each gpio. Negative values are invalid */
- static int tck_gpio = -1;
- static int tms_gpio = -1;
- static int tdi_gpio = -1;
- static int tdo_gpio = -1;
- static int trst_gpio = -1;
- static int srst_gpio = -1;
-
- COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionums)
- {
- if (CMD_ARGC == 4) {
- COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
- COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], tms_gpio);
- COMMAND_PARSE_NUMBER(int, CMD_ARGV[2], tdi_gpio);
- COMMAND_PARSE_NUMBER(int, CMD_ARGV[3], tdo_gpio);
- } else if (CMD_ARGC != 0) {
- return ERROR_COMMAND_SYNTAX_ERROR;
- }
-
- command_print(CMD_CTX,
- "SysfsGPIO nums: tck = %d, tms = %d, tdi = %d, tdi = %d",
- tck_gpio, tms_gpio, tdi_gpio, tdo_gpio);
-
- return ERROR_OK;
- }
-
- COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tck)
- {
- if (CMD_ARGC == 1)
- COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
-
- command_print(CMD_CTX, "SysfsGPIO num: tck = %d", tck_gpio);
- return ERROR_OK;
- }
-
- COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tms)
- {
- if (CMD_ARGC == 1)
- COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tms_gpio);
-
- command_print(CMD_CTX, "SysfsGPIO num: tms = %d", tms_gpio);
- return ERROR_OK;
- }
-
- COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdo)
- {
- if (CMD_ARGC == 1)
- COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdo_gpio);
-
- command_print(CMD_CTX, "SysfsGPIO num: tdo = %d", tdo_gpio);
- return ERROR_OK;
- }
-
- COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdi)
- {
- if (CMD_ARGC == 1)
- COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdi_gpio);
-
- command_print(CMD_CTX, "SysfsGPIO num: tdi = %d", tdi_gpio);
- return ERROR_OK;
- }
-
- COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_srst)
- {
- if (CMD_ARGC == 1)
- COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], srst_gpio);
-
- command_print(CMD_CTX, "SysfsGPIO num: srst = %d", srst_gpio);
- return ERROR_OK;
- }
-
- COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_trst)
- {
- if (CMD_ARGC == 1)
- COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], trst_gpio);
-
- command_print(CMD_CTX, "SysfsGPIO num: trst = %d", trst_gpio);
- return ERROR_OK;
- }
-
- static const struct command_registration sysfsgpio_command_handlers[] = {
- {
- .name = "sysfsgpio_jtag_nums",
- .handler = &sysfsgpio_handle_jtag_gpionums,
- .mode = COMMAND_CONFIG,
- .help = "gpio numbers for tck, tms, tdi, tdo. (in that order)",
- .usage = "(tck tms tdi tdo)* ",
- },
- {
- .name = "sysfsgpio_tck_num",
- .handler = &sysfsgpio_handle_jtag_gpionum_tck,
- .mode = COMMAND_CONFIG,
- .help = "gpio number for tck.",
- },
- {
- .name = "sysfsgpio_tms_num",
- .handler = &sysfsgpio_handle_jtag_gpionum_tms,
- .mode = COMMAND_CONFIG,
- .help = "gpio number for tms.",
- },
- {
- .name = "sysfsgpio_tdo_num",
- .handler = &sysfsgpio_handle_jtag_gpionum_tdo,
- .mode = COMMAND_CONFIG,
- .help = "gpio number for tdo.",
- },
- {
- .name = "sysfsgpio_tdi_num",
- .handler = &sysfsgpio_handle_jtag_gpionum_tdi,
- .mode = COMMAND_CONFIG,
- .help = "gpio number for tdi.",
- },
- {
- .name = "sysfsgpio_srst_num",
- .handler = &sysfsgpio_handle_jtag_gpionum_srst,
- .mode = COMMAND_CONFIG,
- .help = "gpio number for srst.",
- },
- {
- .name = "sysfsgpio_trst_num",
- .handler = &sysfsgpio_handle_jtag_gpionum_trst,
- .mode = COMMAND_CONFIG,
- .help = "gpio number for trst.",
- },
- COMMAND_REGISTRATION_DONE
- };
-
- static int sysfsgpio_init(void);
- static int sysfsgpio_quit(void);
-
- struct jtag_interface sysfsgpio_interface = {
- .name = "sysfsgpio",
- .supported = DEBUG_CAP_TMS_SEQ,
- .execute_queue = bitbang_execute_queue,
- .transports = jtag_only,
- .commands = sysfsgpio_command_handlers,
- .init = sysfsgpio_init,
- .quit = sysfsgpio_quit,
- };
-
- static struct bitbang_interface sysfsgpio_bitbang = {
- .read = sysfsgpio_read,
- .write = sysfsgpio_write,
- .reset = sysfsgpio_reset,
- .blink = 0
- };
-
- /* helper func to close and cleanup files only if they were valid/ used */
- static void cleanup_fd(int fd, int gpio)
- {
- if (gpio >= 0) {
- if (fd >= 0)
- close(fd);
-
- unexport_sysfs_gpio(gpio);
- }
- }
-
- static void cleanup_all_fds(void)
- {
- cleanup_fd(tck_fd, tck_gpio);
- cleanup_fd(tms_fd, tms_gpio);
- cleanup_fd(tdi_fd, tdi_gpio);
- cleanup_fd(tdo_fd, tdo_gpio);
- cleanup_fd(trst_fd, trst_gpio);
- cleanup_fd(srst_fd, srst_gpio);
- }
-
- static int sysfsgpio_init(void)
- {
- bitbang_interface = &sysfsgpio_bitbang;
-
- LOG_INFO("SysfsGPIO JTAG bitbang driver");
-
- if (!(is_gpio_valid(tck_gpio)
- && is_gpio_valid(tms_gpio)
- && is_gpio_valid(tdi_gpio)
- && is_gpio_valid(tdo_gpio))) {
- if (!is_gpio_valid(tck_gpio))
- LOG_ERROR("gpio num for tck is invalid");
- if (!is_gpio_valid(tms_gpio))
- LOG_ERROR("gpio num for tms is invalid");
- if (!is_gpio_valid(tdo_gpio))
- LOG_ERROR("gpio num for tdo is invalid");
- if (!is_gpio_valid(tdi_gpio))
- LOG_ERROR("gpio num for tdi is invalid");
-
- LOG_ERROR("Require tck, tms, tdi and tdo gpios to all be specified");
- return ERROR_JTAG_INIT_FAILED;
- }
-
- if (!is_gpio_valid(trst_gpio) && !is_gpio_valid(srst_gpio)) {
- LOG_ERROR("Require at least one of trst or srst gpios to be specified");
- return ERROR_JTAG_INIT_FAILED;
- }
-
- /*
- * Configure TDO as an input, and TDI, TCK, TMS, TRST, SRST
- * as outputs. Drive TDI and TCK low, and TMS/TRST/SRST high.
- */
- tck_fd = setup_sysfs_gpio(tck_gpio, 1, 0);
- if (tck_fd < 0)
- goto out_error;
-
- tms_fd = setup_sysfs_gpio(tms_gpio, 1, 1);
- if (tms_fd < 0)
- goto out_error;
-
- tdi_fd = setup_sysfs_gpio(tdi_gpio, 1, 0);
- if (tdi_fd < 0)
- goto out_error;
-
- tdo_fd = setup_sysfs_gpio(tdo_gpio, 0, 0);
- if (tdo_fd < 0)
- goto out_error;
-
- /* assume active low*/
- trst_fd = setup_sysfs_gpio(trst_gpio, 1, 1);
- if (trst_gpio > 0 && trst_fd < 0)
- goto out_error;
-
- /* assume active low*/
- srst_fd = setup_sysfs_gpio(srst_gpio, 1, 1);
- if (srst_gpio > 0 && srst_fd < 0)
- goto out_error;
-
- return ERROR_OK;
-
- out_error:
- cleanup_all_fds();
- return ERROR_JTAG_INIT_FAILED;
- }
-
- static int sysfsgpio_quit(void)
- {
- cleanup_all_fds();
- return ERROR_OK;
- }
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