[PATCH v11 4/6] selftests: gpio: provide a helper for reading chip info

[Bartosz Golaszewski <brgl@bgdev.pl>]

Add a simple program that allows to retrieve chip properties from the
GPIO character device. This will be used in gpio-sim selftests.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
 tools/testing/selftests/gpio/.gitignore       |  1 +
 tools/testing/selftests/gpio/Makefile         |  2 +-
 tools/testing/selftests/gpio/gpio-chip-info.c | 57 +++++++++++++++++++
 3 files changed, 59 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/gpio/gpio-chip-info.c

diff --git a/tools/testing/selftests/gpio/.gitignore b/tools/testing/selftests/gpio/.gitignore
index a4969f7ee020..4ea4f58dab1a 100644
--- a/tools/testing/selftests/gpio/.gitignore
+++ b/tools/testing/selftests/gpio/.gitignore
@@ -1,2 +1,3 @@
 # SPDX-License-Identifier: GPL-2.0-only
 gpio-mockup-cdev
+gpio-chip-info
diff --git a/tools/testing/selftests/gpio/Makefile b/tools/testing/selftests/gpio/Makefile
index d7b312b44a62..a40b818c394e 100644
--- a/tools/testing/selftests/gpio/Makefile
+++ b/tools/testing/selftests/gpio/Makefile
@@ -2,7 +2,7 @@
 
 TEST_PROGS := gpio-mockup.sh
 TEST_FILES := gpio-mockup-sysfs.sh
-TEST_GEN_PROGS_EXTENDED := gpio-mockup-cdev
+TEST_GEN_PROGS_EXTENDED := gpio-mockup-cdev gpio-chip-info
 CFLAGS += -O2 -g -Wall -I../../../../usr/include/
 
 include ../lib.mk
diff --git a/tools/testing/selftests/gpio/gpio-chip-info.c b/tools/testing/selftests/gpio/gpio-chip-info.c
new file mode 100644
index 000000000000..8f2d2e23e9f6
--- /dev/null
+++ b/tools/testing/selftests/gpio/gpio-chip-info.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * GPIO character device helper for reading chip information.
+ *
+ * Copyright (C) 2021 Bartosz Golaszewski <brgl@bgdev.pl>
+ */
+
+#include <fcntl.h>
+#include <linux/gpio.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+
+static void print_usage(void)
+{
+	printf("usage:\n");
+	printf("  gpio-chip-info <chip path> [name|label|num-lines]\n");
+}
+
+int main(int argc, char **argv)
+{
+	struct gpiochip_info info;
+	int fd, ret;
+
+	if (argc !=3) {
+		print_usage();
+		return EXIT_FAILURE;
+	}
+
+	fd = open(argv[1], O_RDWR);
+	if (fd < 0) {
+		perror("unable to open the GPIO chip");
+		return EXIT_FAILURE;
+	}
+
+	memset(&info, 0, sizeof(info));
+	ret = ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &info);
+	if (ret) {
+		perror("chip info ioctl failed");
+		return EXIT_FAILURE;
+	}
+
+	if (strcmp(argv[2], "name") == 0) {
+		printf("%s\n", info.name);
+	} else if (strcmp(argv[2], "label") == 0) {
+		printf("%s\n", info.label);
+	} else if (strcmp(argv[2], "num-lines") == 0) {
+		printf("%u\n", info.lines);
+	} else {
+		fprintf(stderr, "unknown command: %s\n", argv[2]);
+		return EXIT_FAILURE;
+	}
+
+	return EXIT_SUCCESS;
+}
-- 
2.25.1