tools/gpio: create GPIO tools

This creates GPIO tools under tools/gpio/* and adds a single
example program to list the GPIOs on a system. When proper
devices are created it provides this minimal output:

Cc: Johan Hovold <johan@kernel.org>
Cc: Michael Welling <mwelling@ieee.org>
Cc: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

6 files changed, 182 insertions, 3 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 76986c3ab4ff..4d3d1b817873 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4820,6 +4820,7 @@ F:	include/linux/gpio/
 F:      include/linux/gpio.h
 F:      include/asm-generic/gpio.h
 F:      include/uapi/linux/gpio.h
+F:      tools/gpio/
 
 GRE DEMULTIPLEXER DRIVER
 M:      Dmitry Kozlov <xeb@mail.ru>
diff --git a/tools/Makefile b/tools/Makefile
index 6339f6ac3ccb..f41e7c6ea23e 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -13,6 +13,7 @@ help:
         @echo '  cpupower               - a tool for all things x86 CPU power'
         @echo '  firewire               - the userspace part of nosy, an IEEE-1394 traffic sniffer'
         @echo '  freefall               - laptop accelerometer program for disk protection'
+        @echo '  gpio                   - GPIO tools'
         @echo '  hv                     - tools used when in Hyper-V clients'
         @echo '  iio                    - IIO tools'
         @echo '  lguest                 - a minimal 32-bit x86 hypervisor'
@@ -53,7 +54,7 @@ acpi: FORCE
 cpupower: FORCE
         $(call descend,power/$@)
 
-cgroup firewire hv guest spi usb virtio vm net iio: FORCE
+cgroup firewire hv guest spi usb virtio vm net iio gpio: FORCE
         $(call descend,$@)
 
 liblockdep: FORCE
@@ -119,7 +120,7 @@ acpi_clean:
 cpupower_clean:
         $(call descend,power/cpupower,clean)
 
-cgroup_clean hv_clean firewire_clean lguest_clean spi_clean usb_clean virtio_clean vm_clean net_clean iio_clean:
+cgroup_clean hv_clean firewire_clean lguest_clean spi_clean usb_clean virtio_clean vm_clean net_clean iio_clean gpio_clean:
         $(call descend,$(@:_clean=),clean)
 
 liblockdep_clean:
@@ -155,6 +156,7 @@ build_clean:
 clean: acpi_clean cgroup_clean cpupower_clean hv_clean firewire_clean lguest_clean \
                 perf_clean selftests_clean turbostat_clean spi_clean usb_clean virtio_clean \
                 vm_clean net_clean iio_clean x86_energy_perf_policy_clean tmon_clean \
-                freefall_clean build_clean libbpf_clean libsubcmd_clean liblockdep_clean
+                freefall_clean build_clean libbpf_clean libsubcmd_clean liblockdep_clean \
+                gpio_clean
 
 .PHONY: FORCE
diff --git a/tools/gpio/Makefile b/tools/gpio/Makefile
new file mode 100644
index 000000000000..4d198d5c4203
--- /dev/null
+++ b/tools/gpio/Makefile
@@ -0,0 +1,12 @@
+CC = $(CROSS_COMPILE)gcc
+CFLAGS += -Wall -g -D_GNU_SOURCE
+
+all: lsgpio
+
+lsgpio: lsgpio.o gpio-utils.o
+
+%.o: %.c gpio-utils.h
+
+.PHONY: clean
+clean:
+        rm -f *.o lsgpio
diff --git a/tools/gpio/gpio-utils.c b/tools/gpio/gpio-utils.c
new file mode 100644
index 000000000000..8208718f2c99
--- /dev/null
+++ b/tools/gpio/gpio-utils.c
@@ -0,0 +1,11 @@
+/*
+ * GPIO tools - helpers library for the GPIO tools
+ *
+ * Copyright (C) 2015 Linus Walleij
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include "gpio-utils.h"
diff --git a/tools/gpio/gpio-utils.h b/tools/gpio/gpio-utils.h
new file mode 100644
index 000000000000..b18209a45ad3
--- /dev/null
+++ b/tools/gpio/gpio-utils.h
@@ -0,0 +1,25 @@
+/*
+ * GPIO tools - utility helpers library for the GPIO tools
+ *
+ * Copyright (C) 2015 Linus Walleij
+ *
+ * Portions copied from iio_utils and lssio:
+ * Copyright (c) 2010 Manuel Stahl <manuel.stahl@iis.fraunhofer.de>
+ * Copyright (c) 2008 Jonathan Cameron
+ * *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+#ifndef _GPIO_UTILS_H_
+#define _GPIO_UTILS_H_
+
+#include <string.h>
+
+static inline int check_prefix(const char *str, const char *prefix)
+{
+        return strlen(str) > strlen(prefix) &&
+                strncmp(str, prefix, strlen(prefix)) == 0;
+}
+
+#endif /* _GPIO_UTILS_H_ */
diff --git a/tools/gpio/lsgpio.c b/tools/gpio/lsgpio.c
new file mode 100644
index 000000000000..4cfe29da279b
--- /dev/null
+++ b/tools/gpio/lsgpio.c
@@ -0,0 +1,128 @@
+/*
+ * lsgpio - example on how to list the GPIO lines on a system
+ *
+ * Copyright (C) 2015 Linus Walleij
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * Usage:
+ *      lsgpio <-n device-name>
+ */
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <dirent.h>
+#include <errno.h>
+#include <string.h>
+#include <poll.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <sys/ioctl.h>
+#include <linux/gpio.h>
+
+#include "gpio-utils.h"
+
+int list_device(const char *device_name)
+{
+        struct gpiochip_info cinfo;
+        char *chrdev_name;
+        int fd;
+        int ret;
+
+        ret = asprintf(&chrdev_name, "/dev/%s", device_name);
+        if (ret < 0)
+                return -ENOMEM;
+
+        fd = open(chrdev_name, 0);
+        if (fd == -1) {
+                ret = -errno;
+                fprintf(stderr, "Failed to open %s\n", chrdev_name);
+                goto free_chrdev_name;
+        }
+
+        /* Inspect this GPIO chip */
+        ret = ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &cinfo);
+        if (ret == -1) {
+                ret = -errno;
+                fprintf(stderr, "Failed to retrieve GPIO fd\n");
+                if (close(fd) == -1)
+                        perror("Failed to close GPIO character device file");
+
+                goto free_chrdev_name;
+        }
+        fprintf(stdout, "GPIO chip: %s, %u GPIO lines\n",
+                cinfo.name, cinfo.lines);
+
+        if (close(fd) == -1)  {
+                ret = -errno;
+                goto free_chrdev_name;
+        }
+
+free_chrdev_name:
+        free(chrdev_name);
+
+        return ret;
+
+}
+
+void print_usage(void)
+{
+        fprintf(stderr, "Usage: lsgpio [options]...\n"
+                "List GPIO chips, lines and states\n"
+                "  -n <name>  List GPIOs on a named device\n"
+                "  -?         This helptext\n"
+        );
+}
+
+int main(int argc, char **argv)
+{
+        const char *device_name;
+        int ret;
+        int c;
+
+        while ((c = getopt(argc, argv, "n:")) != -1) {
+                switch (c) {
+                case 'n':
+                        device_name = optarg;
+                        break;
+                case '?':
+                        print_usage();
+                        return -1;
+                }
+        }
+
+        if (device_name)
+                ret = list_device(device_name);
+        else {
+                const struct dirent *ent;
+                DIR *dp;
+
+                /* List all GPIO devices one at a time */
+                dp = opendir("/dev");
+                if (!dp) {
+                        ret = -errno;
+                        goto error_out;
+                }
+
+                ret = -ENOENT;
+                while (ent = readdir(dp), ent) {
+                        if (check_prefix(ent->d_name, "gpiochip")) {
+                                ret = list_device(ent->d_name);
+                                if (ret)
+                                        break;
+                        }
+                }
+
+                ret = 0;
+                if (closedir(dp) == -1) {
+                        perror("scanning devices: Failed to close directory");
+                        ret = -errno;
+                }
+        }
+error_out:
+        return ret;
+}