--- /dev/null
+/***************************************************************************
+ * 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;
+
+ if (!first_time) {
+ last_tck = !tck;
+ last_tms = !tms;
+ last_tdi = !tdi;
+ first_time = 1;
+ }
+
+ if (tdi != last_tdi)
+ write(tdi_fd, tdi ? &one : &zero, 1);
+ if (tms != last_tms)
+ write(tms_fd, tms ? &one : &zero, 1);
+ /* write clk last */
+ if (tck != last_tck)
+ write(tck_fd, tck ? &one : &zero, 1);
+
+ 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";
+
+ /* assume active low */
+ if (srst_fd >= 0)
+ write(srst_fd, srst ? &zero : &one, 1);
+
+ /* assume active low */
+ if (trst_fd >= 0)
+ write(trst_fd, trst ? &zero : &one, 1);
+}
+
+/* No speed control is implemented yet */
+static int sysfsgpio_speed(int speed)
+{
+ return ERROR_OK;
+}
+
+static int sysfsgpio_khz(int khz, int *jtag_speed)
+{
+ /* no adaptive clocking */
+ if (khz == 0)
+ return ERROR_FAIL;
+
+ *jtag_speed = 0;
+ return ERROR_OK;
+}
+
+static int sysfsgpio_speed_div(int speed, int *khz)
+{
+ *khz = 1;
+ return ERROR_OK;
+}
+
+/* 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,
+ .speed = sysfsgpio_speed,
+ .khz = sysfsgpio_khz,
+ .speed_div = sysfsgpio_speed_div,
+ .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;
+}
+
projects / openocd / commitdiff