libgpiosim: new library for controlling the gpio-sim module

Add a C library for controlling the gpio-sim kernel module from various
libgpiod test suites. This aims at replacing the old gpio-mockup module
and its user-space library - libgpio-mockup - in the project's tree.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

configure.ac

@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
-# SPDX-FileCopyrightText: 2017-2021 Bartosz Golaszewski <bartekgola@gmail.com>
+# SPDX-FileCopyrightText: 2017-2022 Bartosz Golaszewski <brgl@bgdev.pl>
 
 AC_PREREQ([2.69])
 
@@ -31,6 +31,7 @@ AC_SUBST(ABI_CXX_VERSION, [2.1.1])
 # ABI version for libgpiomockup (we need this since it can be installed if we
 # enable install-tests).
 AC_SUBST(ABI_MOCKUP_VERSION, [0.1.0])
+AC_SUBST(ABI_GPIOSIM_VERSION, [0.1.0])
 
 AC_CONFIG_AUX_DIR([autostuff])
 AC_CONFIG_MACRO_DIRS([m4])
@@ -126,10 +127,11 @@ AC_DEFUN([FUNC_NOT_FOUND_TESTS],
 
 if test "x$with_tests" = xtrue
 then
-	# For libgpiomockup
+	# For libgpiomockup & libgpiosim
 	AC_CHECK_FUNC([qsort], [], [FUNC_NOT_FOUND_TESTS([qsort])])
 	PKG_CHECK_MODULES([KMOD], [libkmod >= 18])
 	PKG_CHECK_MODULES([UDEV], [libudev >= 215])
+	PKG_CHECK_MODULES([MOUNT], [mount >= 2.33.1])
 
 	# For core library tests
 	PKG_CHECK_MODULES([GLIB], [glib-2.0 >= 2.50])
@@ -224,6 +226,7 @@ AC_CONFIG_FILES([Makefile
 		 tools/Makefile
 		 tests/Makefile
 		 tests/mockup/Makefile
+		 tests/gpiosim/Makefile
 		 bindings/cxx/libgpiodcxx.pc
 		 bindings/Makefile
 		 bindings/cxx/Makefile

tests/Makefile.am

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
-# SPDX-FileCopyrightText: 2017-2021 Bartosz Golaszewski <bartekgola@gmail.com>
+# SPDX-FileCopyrightText: 2017-2022 Bartosz Golaszewski <brgl@bgdev.pl>
 
-SUBDIRS = mockup
+SUBDIRS = mockup gpiosim
 
 AM_CFLAGS = -I$(top_srcdir)/include/ -I$(top_srcdir)/tests/mockup/
 AM_CFLAGS += -include $(top_builddir)/config.h

tests/gpiosim/.gitignore

@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# SPDX-FileCopyrightText: 2017-2022 Bartosz Golaszewski <brgl@bgdev.pl>
+
+gpiosim-selftest

tests/gpiosim/Makefile.am

@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# SPDX-FileCopyrightText: 2021-2022 Bartosz Golaszewski <brgl@bgdev.pl>
+
+lib_LTLIBRARIES = libgpiosim.la
+noinst_PROGRAMS = gpiosim-selftest
+
+AM_CFLAGS = -Wall -Wextra -g -fvisibility=hidden -std=gnu89
+AM_CFLAGS += -include $(top_builddir)/config.h
+
+libgpiosim_la_SOURCES = gpiosim.c gpiosim.h
+libgpiosim_la_CFLAGS = $(AM_CFLAGS) $(KMOD_CFLAGS) $(MOUNT_CFLAGS)
+libgpiosim_la_LDFLAGS = -version-info $(subst .,:,$(ABI_GPIOSIM_VERSION))
+libgpiosim_la_LDFLAGS += $(KMOD_LIBS) $(MOUNT_LIBS)
+
+gpiosim_selftest_SOURCES = gpiosim-selftest.c
+gpiosim_selftest_LDADD = libgpiosim.la

tests/gpiosim/gpiosim-selftest.c

@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2021-2022 Bartosz Golaszewski <brgl@bgdev.pl>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "gpiosim.h"
+
+#define UNUSED __attribute__((unused))
+
+static const char *const line_names[] = {
+	"foo",
+	"bar",
+	"foobar",
+	NULL,
+	"barfoo",
+};
+
+int main(int argc UNUSED, char **argv UNUSED)
+{
+	struct gpiosim_bank *bank0, *bank1;
+	struct gpiosim_dev *dev;
+	struct gpiosim_ctx *ctx;
+	int ret, i;
+
+	printf("Creating gpiosim context\n");
+
+	ctx = gpiosim_ctx_new();
+	if (!ctx) {
+		perror("unable to create the gpios-sim context");
+		return EXIT_FAILURE;
+	}
+
+	printf("Creating a chip with random name\n");
+
+	dev = gpiosim_dev_new(ctx, NULL);
+	if (!dev) {
+		perror("Unable to create a chip with random name");
+		return EXIT_FAILURE;
+	}
+
+	printf("Creating a bank with a random name\n");
+
+	bank0 = gpiosim_bank_new(dev, NULL);
+	if (!bank0) {
+		perror("Unable to create a bank with random name");
+		return EXIT_FAILURE;
+	}
+
+	printf("Creating a bank with a specific name\n");
+
+	bank1 = gpiosim_bank_new(dev, "foobar");
+	if (!bank1) {
+		perror("Unable to create a bank with a specific name");
+		return EXIT_FAILURE;
+	}
+
+	printf("Setting the label of bank #2 to foobar\n");
+
+	ret = gpiosim_bank_set_label(bank1, "foobar");
+	if (ret) {
+		perror("Unable to set the label of bank #2");
+		return EXIT_FAILURE;
+	}
+
+	printf("Setting the number of lines in bank #1 to 16\n");
+
+	ret = gpiosim_bank_set_num_lines(bank0, 16);
+	if (ret) {
+		perror("Unable to set the number of lines");
+		return EXIT_FAILURE;
+	}
+
+	printf("Setting the number of lines in bank #2 to 8\n");
+
+	ret = gpiosim_bank_set_num_lines(bank1, 8);
+	if (ret) {
+		perror("Unable to set the number of lines");
+		return EXIT_FAILURE;
+	}
+
+	printf("Setting names for some lines in bank #1\n");
+
+	for (i = 0; i < 5; i++) {
+		ret = gpiosim_bank_set_line_name(bank0, i, line_names[i]);
+		if (ret) {
+			perror("Unable to set line names");
+			return EXIT_FAILURE;
+		}
+	}
+
+	printf("Hog a line on bank #2\n");
+
+	ret = gpiosim_bank_hog_line(bank1, 3, "xyz",
+				    GPIOSIM_HOG_DIR_OUTPUT_HIGH);
+	if (ret) {
+		perror("Unable to hog a line");
+		return EXIT_FAILURE;
+	}
+
+	printf("Enabling the GPIO device\n");
+
+	ret = gpiosim_dev_enable(dev);
+	if (ret) {
+		perror("Unable to enable the device");
+		return EXIT_FAILURE;
+	}
+
+	printf("Setting the pull of a single line to pull-up\n");
+
+	ret = gpiosim_bank_set_pull(bank0, 6, GPIOSIM_PULL_UP);
+	if (ret) {
+		perror("Unable to set the pull");
+		return EXIT_FAILURE;
+	}
+
+	printf("Reading the pull back\n");
+
+	ret = gpiosim_bank_get_pull(bank0, 6);
+	if (ret < 0) {
+		perror("Unable to read the pull");
+		return EXIT_FAILURE;
+	}
+
+	if (ret != GPIOSIM_PULL_UP) {
+		fprintf(stderr, "Invalid pull value read\n");
+		return EXIT_FAILURE;
+	}
+
+	printf("Reading the value\n");
+
+	ret = gpiosim_bank_get_value(bank0, 6);
+	if (ret < 0) {
+		perror("Unable to read the value");
+		return EXIT_FAILURE;
+	}
+
+	if (ret != 1) {
+		fprintf(stderr, "Invalid value read\n");
+		return EXIT_FAILURE;
+	}
+
+	printf("Disabling the GPIO device\n");
+
+	ret = gpiosim_dev_disable(dev);
+	if (ret) {
+		perror("Error while disabling the device");
+		return EXIT_FAILURE;
+	}
+
+	gpiosim_bank_unref(bank1);
+	gpiosim_bank_unref(bank0);
+	gpiosim_dev_unref(dev);
+	gpiosim_ctx_unref(ctx);
+
+	return EXIT_SUCCESS;
+}

tests/gpiosim/gpiosim.h

@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/* SPDX-FileCopyrightText: 2021-2022 Bartosz Golaszewski <brgl@bgdev.pl> */
+
+#ifndef __GPIOD_GPIOSIM_H__
+#define __GPIOD_GPIOSIM_H__
+
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct gpiosim_ctx;
+struct gpiosim_dev;
+struct gpiosim_bank;
+
+enum {
+	GPIOSIM_PULL_DOWN = 1,
+	GPIOSIM_PULL_UP,
+};
+
+enum {
+	GPIOSIM_HOG_DIR_INPUT = 1,
+	GPIOSIM_HOG_DIR_OUTPUT_HIGH,
+	GPIOSIM_HOG_DIR_OUTPUT_LOW,
+};
+
+struct gpiosim_ctx *gpiosim_ctx_new(void);
+struct gpiosim_ctx *gpiosim_ctx_ref(struct gpiosim_ctx *ctx);
+void gpiosim_ctx_unref(struct gpiosim_ctx *ctx);
+
+struct gpiosim_dev *
+gpiosim_dev_new(struct gpiosim_ctx *ctx, const char *name);
+struct gpiosim_dev *gpiosim_dev_ref(struct gpiosim_dev *dev);
+void gpiosim_dev_unref(struct gpiosim_dev *dev);
+struct gpiosim_ctx *gpiosim_dev_get_ctx(struct gpiosim_dev *dev);
+const char *gpiosim_dev_get_name(struct gpiosim_dev *dev);
+
+int gpiosim_dev_enable(struct gpiosim_dev *dev);
+int gpiosim_dev_disable(struct gpiosim_dev *dev);
+bool gpiosim_dev_is_live(struct gpiosim_dev *dev);
+
+struct gpiosim_bank*
+gpiosim_bank_new(struct gpiosim_dev *dev, const char *name);
+struct gpiosim_bank *gpiosim_bank_ref(struct gpiosim_bank *bank);
+void gpiosim_bank_unref(struct gpiosim_bank *bank);
+struct gpiosim_dev *gpiosim_bank_get_dev(struct gpiosim_bank *bank);
+const char *gpiosim_bank_get_chip_name(struct gpiosim_bank *bank);
+const char *gpiosim_bank_get_dev_path(struct gpiosim_bank *bank);
+
+int gpiosim_bank_set_label(struct gpiosim_bank *bank, const char *label);
+int gpiosim_bank_set_num_lines(struct gpiosim_bank *bank,
+			       unsigned int num_lines);
+int gpiosim_bank_set_line_name(struct gpiosim_bank *bank,
+			       unsigned int offset, const char *name);
+int gpiosim_bank_hog_line(struct gpiosim_bank *bank, unsigned int offset,
+			  const char *name, int direction);
+int gpiosim_bank_clear_hog(struct gpiosim_bank *bank, unsigned int offset);
+
+int gpiosim_bank_get_value(struct gpiosim_bank *bank, unsigned int offset);
+int gpiosim_bank_get_pull(struct gpiosim_bank *bank, unsigned int offset);
+int gpiosim_bank_set_pull(struct gpiosim_bank *bank,
+			  unsigned int offset, int pull);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* __GPIOD_GPIOSIM_H__ */