gpio: add initial implementation.

4 files changed, 247 insertions, 3 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index de86e4c..1717659 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -14,7 +14,7 @@
 # License along with this library; if not, write to the Free Software
 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 
-SUBDIRS = float diagnostic
+SUBDIRS = float diagnostic gpio
 
 AM_CFLAGS = \
 	-I$(top_srcdir)/include/ \
@@ -33,11 +33,13 @@ librin_la_SOURCES = dummy.c
 
 librin_la_LIBADD = \
 	float/librin_float.la \
-	diagnostic/librin_diagnostic.la
+	diagnostic/librin_diagnostic.la \
+	gpio/librin_gpio.la
 
 librin_includedir = $(includedir)/rin
 librin_include_HEADERS = \
 	$(top_srcdir)/include/rin/float.h \
 	$(top_srcdir)/include/rin/float_types.h \
 	$(top_srcdir)/include/rin/definitions.h \
-	$(top_srcdir)/include/rin/diagnostic.h
+	$(top_srcdir)/include/rin/diagnostic.h \
+	$(top_srcdir)/include/rin/gpio.h
diff --git a/src/gpio/Makefile.am b/src/gpio/Makefile.am
new file mode 100644
index 0000000..e009cab
--- /dev/null
+++ b/src/gpio/Makefile.am
@@ -0,0 +1,26 @@
+# Copyright (C) 2016 Gediminas Jakutis
+#
+# This Makefile.am is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; version 2.1
+# of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+
+AM_CFLAGS = \
+	-I$(top_srcdir)/include/ \
+	-Wall \
+	-Wextra
+
+noinst_LTLIBRARIES = librin_gpio.la
+
+librin_gpio_la_SOURCES = \
+	gpio.c \
+	gpio_private.h
diff --git a/src/gpio/gpio.c b/src/gpio/gpio.c
new file mode 100644
index 0000000..45639a3
--- /dev/null
+++ b/src/gpio/gpio.c
@@ -0,0 +1,172 @@
+/*
+ * The Rin Library – gpio module
+ *
+ * Copyright (C) 2016 Gediminas Jakutis
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; version 2.1
+ * of the License.
+ *
+ * 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+#include "rin/gpio.h"
+#include "gpio_private.h"
+
+unsigned int rin_gpio_open(const unsigned int num, const enum rin_gpiotype type)
+{
+	struct stat st;
+	struct timespec grace = { 0, 1 * 1000 * 1000 }; /* 1 ms */
+	char buf[48] = { 0 };
+	int fd;
+	unsigned int timeout;
+
+	init();
+
+	if (type == rin_gpio_closed || !rin_gpio_pin_exists(num) || gpio[num].type != rin_gpio_closed) {
+		return 1;
+	}
+
+	fd = open("/sys/class/gpio/export", O_WRONLY | O_DSYNC);
+	sprintf(buf, "%u", num);
+	write(fd, buf, strlen(buf));
+	close(fd);
+	sprintf(buf, "/sys/class/gpio/gpio%u/direction", num);
+	timeout = 500; /* 500 ms, if it takes longer, something ain't right. */
+	while (stat(buf, &st)) {
+		nanosleep(&grace, NULL);
+		if (!(--timeout)) {
+			return 1;
+		}
+	}
+	fd = open(buf, O_WRONLY | O_DSYNC);
+	if (type == rin_gpio_in) {
+		write(fd, "in", 2);
+	} else {
+		write(fd, "out", 3);
+	}
+	close(fd);
+	gpio[num].type = type;
+	sprintf(buf, "/sys/class/gpio/gpio%u/value", num);
+	if (type == rin_gpio_in) {
+		gpio[num].fd = open(buf, O_RDONLY);
+	} else {
+		gpio[num].fd = open(buf, O_WRONLY);
+	}
+
+	return 0;
+}
+
+unsigned int rin_gpio_close(const unsigned int num)
+{
+	char buf[32] = { 0 };
+	struct stat st;
+	int fd;
+
+	init();
+	sprintf(buf, "/sys/class/gpio/gpio%u", num);
+	if (stat(buf, &st)) {
+		return 0;
+	}
+	close(gpio[num].fd);
+	gpio[num].fd = -1;
+	fd = open("/sys/class/gpio/unexport", O_WRONLY);
+	sprintf(buf, "%u", num);
+	write(fd, buf, strlen(buf));
+	close(fd);
+	gpio[num].type = rin_gpio_closed;
+	return 0;
+}
+
+unsigned int rin_gpio_setval(const unsigned int num, const unsigned int val)
+{
+	char buf[8] = { 0 };
+
+	init();
+	if (!rin_gpio_pin_exists(num) || gpio[num].type != rin_gpio_out) {
+		return 1;
+	}
+	sprintf(buf, "%u", val);
+	lseek(gpio[num].fd, 0, SEEK_SET);
+	write(gpio[num].fd, buf, strlen(buf));
+	return 0;
+}
+
+unsigned int rin_gpio_readval(const unsigned int num, unsigned int * const val)
+{
+	init();
+
+	if (!rin_gpio_pin_exists(num) || gpio[num].type != rin_gpio_in) {
+		exit(EXIT_FAILURE);
+	}
+
+	lseek(gpio[num].fd, 0, SEEK_SET);
+	read(gpio[num].fd, val, 1);
+
+	if (*val >= '0') {
+		*val -= '0';
+	}
+
+	return 0;
+}
+
+/*
+ * right now is rpi V1 specific, should be rewritten when/if we support
+ * other platforms.
+ */
+unsigned int rin_gpio_pin_exists(const unsigned int pin)
+{
+	switch (pin) {
+	case 2:
+	case 3:
+	case 4:
+	case 7:
+	case 8:
+	case 9:
+	case 10:
+	case 11:
+	case 14:
+	case 15:
+	case 17:
+	case 18:
+	case 22:
+	case 23:
+	case 24:
+	case 25:
+		return 1;
+	default:
+		return 0;
+	}
+}
+
+/*
+ * in case we ever support hardware other than the V1 Raspberry,
+ * we need this to get the pin usable pin count
+ */
+unsigned int rin_gpio_get_pincount(void)
+{
+	return 16;
+}
+
+static void init(void)
+{
+	size_t i;
+	static unsigned int firstrun = 1;
+
+	if (firstrun) {
+		firstrun = 0;
+		for (i = 0; i < gpio_count; ++i) {
+			gpio[i].num = i;
+			gpio[i].type = rin_gpio_closed;
+			gpio[i].fd = -1;
+		}
+	}
+}
diff --git a/src/gpio/gpio_private.h b/src/gpio/gpio_private.h
new file mode 100644
index 0000000..4a22570
--- /dev/null
+++ b/src/gpio/gpio_private.h
@@ -0,0 +1,44 @@
+/*
+ * The Rin Library – gpio module
+ *
+ * Copyright (C) 2016 Gediminas Jakutis
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; version 2.1
+ * of the License.
+ *
+ * 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+#ifndef GPIO_PRIVATE_H_INCLUDED
+#define GPIO_PRIVATE_H_INCLUDED
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <time.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+/* TODO: make this platform-dependent */
+#define gpio_count 32
+
+static struct gpio {
+	unsigned int num;
+	enum rin_gpiotype type;
+	int fd;
+} gpio[gpio_count];
+
+static void init(void);
+
+#endif /* GPIO_PRIVATE_H_INCLUDED */