drivers/am335xgpio: Add AM335x driver for bitbang support on BeagleBones

Change-Id: Iac1c9f3d380e2474c8b77407c89c2aad96fbf2ea
Signed-off-by: Steve Marple <stevemarple@googlemail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6941
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

configure.ac

@@ -298,10 +298,14 @@ AS_CASE(["${host_cpu}"],
     AC_ARG_ENABLE([imx_gpio],
       AS_HELP_STRING([--enable-imx_gpio], [Enable building support for bitbanging on NXP IMX processors]),
       [build_imx_gpio=$enableval], [build_imx_gpio=no])
+    AC_ARG_ENABLE([am335xgpio],
+      AS_HELP_STRING([--enable-am335xgpio], [Enable building support for bitbanging on AM335x (as found in Beaglebones)]),
+      [build_am335xgpio=$enableval], [build_am335xgpio=no])
   ],
   [
     build_bcm2835gpio=no
     build_imx_gpio=no
+    build_am335xgpio=no
 ])
 
 AS_CASE(["${host_cpu}"],
@@ -507,6 +511,13 @@ AS_IF([test "x$build_imx_gpio" = "xyes"], [
   AC_DEFINE([BUILD_IMX_GPIO], [0], [0 if you don't want imx_gpio.])
 ])
 
+AS_IF([test "x$build_am335xgpio" = "xyes"], [
+  build_bitbang=yes
+  AC_DEFINE([BUILD_AM335XGPIO], [1], [1 if you want am335xgpio.])
+], [
+  AC_DEFINE([BUILD_AM335XGPIO], [0], [0 if you don't want am335xgpio.])
+])
+
 AS_IF([test "x$parport_use_ppdev" = "xyes"], [
   AC_DEFINE([PARPORT_USE_PPDEV], [1], [1 if you want parport to use ppdev.])
 ], [
@@ -711,6 +722,7 @@ AM_CONDITIONAL([EP93XX], [test "x$build_ep93xx" = "xyes"])
 AM_CONDITIONAL([AT91RM9200], [test "x$build_at91rm9200" = "xyes"])
 AM_CONDITIONAL([BCM2835GPIO], [test "x$build_bcm2835gpio" = "xyes"])
 AM_CONDITIONAL([IMX_GPIO], [test "x$build_imx_gpio" = "xyes"])
+AM_CONDITIONAL([AM335XGPIO], [test "x$build_am335xgpio" = "xyes"])
 AM_CONDITIONAL([BITBANG], [test "x$build_bitbang" = "xyes"])
 AM_CONDITIONAL([JTAG_VPI], [test "x$build_jtag_vpi" = "xyes"])
 AM_CONDITIONAL([VDEBUG], [test "x$build_vdebug" = "xyes"])

doc/openocd.texi

@@ -584,6 +584,9 @@ produced, PDF schematics are easily found and it is easy to make.
 @item @b{imx_gpio}
 @* A NXP i.MX-based board (e.g. Wandboard) using the GPIO pins (should work on any i.MX processor).
 
+@item @b{am335xgpio}
+@* A Texas Instruments AM335x-based board (e.g. BeagleBone Black) using the GPIO pins of the expansion headers.
+
 @item @b{jtag_vpi}
 @* A JTAG driver acting as a client for the JTAG VPI server interface.
 @* Link: @url{http://github.com/fjullien/jtag_vpi}
@@ -3322,6 +3325,98 @@ pinout.
 @end deffn
 
 
+@deffn {Interface Driver} {am335xgpio} The AM335x SoC is present in BeagleBone
+Black and BeagleBone Green single-board computers which expose some of the GPIOs
+on the two expansion headers.
+
+For maximum performance the driver accesses memory-mapped GPIO peripheral
+registers directly. The memory mapping requires read and write permission to
+kernel memory; if /dev/gpiomem exists it will be used, otherwise /dev/mem will
+be used. The driver restores the GPIO state on exit.
+
+All four GPIO ports are available. GPIOs numbered 0 to 31 are mapped to GPIO port
+0, GPIO numbers 32 to 63 are mapped to GPIO port 1 and so on.
+
+See @file{interface/beaglebone-swd-native.cfg} for a sample configuration file.
+
+@deffn {Config Command} {am335xgpio jtag_nums} @var{tck} @var{tms} @var{tdi} @var{tdo}
+Set JTAG transport GPIO numbers for TCK, TMS, TDI, and TDO (in that order).
+Must be specified to enable JTAG transport. These pins can also be specified
+individually.
+@end deffn
+
+@deffn {Config Command} {am335xgpio tck_num} @var{tck}
+Set TCK GPIO number. Must be specified to enable JTAG transport. Can also be
+specified using the configuration command @command{am335xgpio jtag_nums}.
+@end deffn
+
+@deffn {Config Command} {am335xgpio tms_num} @var{tms}
+Set TMS GPIO number. Must be specified to enable JTAG transport. Can also be
+specified using the configuration command @command{am335xgpio jtag_nums}.
+@end deffn
+
+@deffn {Config Command} {am335xgpio tdo_num} @var{tdo}
+Set TDO GPIO number. Must be specified to enable JTAG transport. Can also be
+specified using the configuration command @command{am335xgpio jtag_nums}.
+@end deffn
+
+@deffn {Config Command} {am335xgpio tdi_num} @var{tdi}
+Set TDI GPIO number. Must be specified to enable JTAG transport. Can also be
+specified using the configuration command @command{am335xgpio jtag_nums}.
+@end deffn
+
+@deffn {Config Command} {am335xgpio swd_nums} @var{swclk} @var{swdio}
+Set SWD transport GPIO numbers for SWCLK and SWDIO (in that order). Must be
+specified to enable SWD transport. These pins can also be specified individually.
+@end deffn
+
+@deffn {Config Command} {am335xgpio swclk_num} @var{swclk}
+Set SWCLK GPIO number. Must be specified to enable SWD transport. Can also be
+specified using the configuration command @command{am335xgpio swd_nums}.
+@end deffn
+
+@deffn {Config Command} {am335xgpio swdio_num} @var{swdio}
+Set SWDIO GPIO number. Must be specified to enable SWD transport. Can also be
+specified using the configuration command @command{am335xgpio swd_nums}.
+@end deffn
+
+@deffn {Config Command} {am335xgpio swdio_dir_num} @var{swdio_dir}
+Set SWDIO direction control pin GPIO number. If specified, this pin can be used
+to control the direction of an external buffer on the SWDIO pin. The direction
+control state can be set with the command @command{am335xgpio
+swdio_dir_output_state}. If not specified this feature is disabled.
+@end deffn
+
+@deffn {Config Command} {am335xgpio swdio_dir_output_state} @var{output_state}
+Set the state required for an external SWDIO buffer to be an output. Valid
+values are @option{on} (default) and @option{off}.
+@end deffn
+
+@deffn {Config Command} {am335xgpio srst_num} @var{srst}
+Set SRST GPIO number. Must be specified to enable SRST.
+@end deffn
+
+@deffn {Config Command} {am335xgpio trst_num} @var{trst}
+Set TRST GPIO number. Must be specified to enable TRST.
+@end deffn
+
+@deffn {Config Command} {am335xgpio led_num} @var{led}
+Set activity LED GPIO number. If not specified an activity LED is not enabled.
+@end deffn
+
+@deffn {Config Command} {am335xgpio led_on_state} @var{on_state}
+Set required logic level for the LED to be on. Valid values are @option{on}
+(default) and @option{off}.
+@end deffn
+
+@deffn {Config Command} {am335xgpio speed_coeffs} @var{speed_coeff} @var{speed_offset}
+Set SPEED_COEFF and SPEED_OFFSET for delay calculations. If unspecified
+speed_coeff defaults to 600000 and speed_offset defaults to 575.
+@end deffn
+
+@end deffn
+
+
 @deffn {Interface Driver} {linuxgpiod}
 Linux provides userspace access to GPIO through libgpiod since Linux kernel version v4.6.
 The driver emulates either JTAG and SWD transport through bitbanging.

src/jtag/drivers/Makefile.am

@@ -185,6 +185,9 @@ endif
 if XDS110
 DRIVERFILES += %D%/xds110.c
 endif
+if AM335XGPIO
+DRIVERFILES += %D%/am335xgpio.c
+endif
 
 DRIVERHEADERS = \
 	%D%/bitbang.h \

src/jtag/interfaces.c

@@ -150,6 +150,9 @@ extern struct adapter_driver stlink_dap_adapter_driver;
 #if BUILD_RSHIM == 1
 extern struct adapter_driver rshim_dap_adapter_driver;
 #endif
+#if BUILD_AM335XGPIO == 1
+extern struct adapter_driver am335xgpio_adapter_driver;
+#endif
 
 /**
  * The list of built-in JTAG interfaces, containing entries for those
@@ -263,6 +266,9 @@ struct adapter_driver *adapter_drivers[] = {
 #endif
 #if BUILD_RSHIM == 1
 		&rshim_dap_adapter_driver,
+#endif
+#if BUILD_AM335XGPIO == 1
+		&am335xgpio_adapter_driver,
 #endif
 		NULL,
 	};

tcl/interface/beaglebone-jtag-native.cfg

@@ -0,0 +1,28 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# BeagleBone native GPIO interface for JTAG
+#
+# This is best used with a fast buffer but it is also suitable for a direct
+# connection if the target voltage matches the host's IO voltage (typically
+# 3.3V) and the cable is short.
+#
+# DO NOT APPLY VOLTAGE TO THE GPIO PINS UNTIL SYS_RESETN IS HIGH.
+#
+# Do not forget the GND connection.
+
+adapter driver am335xgpio
+
+# Transition delay calculation: SPEED_COEFF/khz - SPEED_OFFSET
+# These depend on the system clock, calibrated for stock 1 GHz BeagleBoneBlack
+# am335xgpio speed SPEED_COEFF SPEED_OFFSET
+am335xgpio speed_coeffs 600000 575
+
+am335xgpio tdo_num 20
+am335xgpio tdi_num 60
+am335xgpio tms_num 4
+am335xgpio tck_num 2
+
+am335xgpio led_num 51
+am335xgpio led_on_state on
+
+am335xgpio srst_num 65
+reset_config srst_only srst_push_pull

tcl/interface/beaglebone-swd-native.cfg

@@ -0,0 +1,29 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# BeagleBone native GPIO interface for SWD
+#
+# This is best used with a fast buffer but it is also suitable for a direct
+# connection if the target voltage matches the host's IO voltage (typically
+# 3.3V) and the cable is short.
+#
+# DO NOT APPLY VOLTAGE TO THE GPIO PINS UNTIL SYS_RESETN IS HIGH.
+#
+# Do not forget the GND connection.
+
+adapter driver am335xgpio
+
+# Transition delay calculation: SPEED_COEFF/khz - SPEED_OFFSET
+# These depend on the system clock, calibrated for stock 1 GHz BeagleBoneBlack
+# am335xgpio speed SPEED_COEFF SPEED_OFFSET
+am335xgpio speed_coeffs 600000 575
+
+am335xgpio swclk_num 2
+am335xgpio swdio_num 4
+am335xgpio swdio_dir_num 60
+am335xgpio swdio_dir_output_state on
+
+# USR0 LED
+am335xgpio led_num 53
+am335xgpio led_on_state on
+
+am335xgpio srst_num 65
+reset_config srst_only srst_push_pull