baylibre-acme: Add Linux-specific GPIO helpers.

These functions allow to export, read and set GPIOs using Linux
sysfs interface.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Makefile.am

@@ -151,7 +151,9 @@ if HW_BAYLIBRE_ACME
 libsigrok_la_SOURCES += \
 	src/hardware/baylibre-acme/protocol.h \
 	src/hardware/baylibre-acme/protocol.c \
-	src/hardware/baylibre-acme/api.c
+	src/hardware/baylibre-acme/api.c \
+	src/hardware/baylibre-acme/gpio.h \
+	src/hardware/baylibre-acme/gpio.c
 endif
 if HW_BEAGLELOGIC
 libsigrok_la_SOURCES += \

src/hardware/baylibre-acme/gpio.c

@@ -0,0 +1,169 @@
+/*
+ * This file is part of the libsigrok project.
+ *
+ * Copyright (C) 2015 Bartosz Golaszewski <bgolaszewski@baylibre.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "libsigrok.h"
+#include "libsigrok-internal.h"
+#include "gpio.h"
+#include <glib.h>
+#include <glib/gstdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <string.h>
+
+#define LOG_PREFIX "gpio"
+
+static int open_and_write(const gchar *path, const gchar *buf)
+{
+	FILE *fd;
+	ssize_t wr;
+
+	fd = g_fopen(path, "w");
+	if (!fd) {
+		sr_err("error opening %s: %s", path, strerror(errno));
+		return -1;
+	}
+
+	wr = g_fprintf(fd, "%s", buf);
+	fclose(fd);
+	if (wr < 0) {
+		sr_err("error writing to %s: %s", path, strerror(errno));
+		return -1;
+	}
+
+	return 0;
+}
+
+SR_PRIV int sr_gpio_export(unsigned gpio)
+{
+	GString *path, *buf;
+	gboolean exported;
+	int status;
+
+	path = g_string_sized_new(128);
+	g_string_printf(path, "/sys/class/gpio/gpio%d", gpio);
+	exported = g_file_test(path->str, G_FILE_TEST_IS_DIR);
+	g_string_free(path, TRUE);
+	if (exported)
+		return 0; /* Already exported. */
+
+	buf = g_string_sized_new(16);
+	g_string_printf(buf, "%u\n", gpio);
+	status = open_and_write("/sys/class/gpio/export", buf->str);
+	g_string_free(buf, TRUE);
+
+	return status;
+}
+
+SR_PRIV int sr_gpio_set_direction(unsigned gpio, unsigned direction)
+{
+	GString *path, *buf;
+	int status;
+
+	path = g_string_sized_new(128);
+	buf = g_string_sized_new(16);
+	g_string_printf(path, "/sys/class/gpio/gpio%d/direction", gpio);
+	g_string_printf(buf, "%s\n", direction == GPIO_DIR_IN ? "in" : "out");
+
+	status = open_and_write(path->str, buf->str);
+
+	g_string_free(path, TRUE);
+	g_string_free(buf, TRUE);
+
+	return status;
+}
+
+SR_PRIV int sr_gpio_set_value(unsigned gpio, unsigned value)
+{
+	GString *path, *buf;
+	int status;
+
+	path = g_string_sized_new(128);
+	buf = g_string_sized_new(16);
+	g_string_printf(path, "/sys/class/gpio/gpio%d/value", gpio);
+	g_string_printf(buf, "%d\n", value);
+
+	status = open_and_write(path->str, buf->str);
+
+	g_string_free(path, TRUE);
+	g_string_free(buf, TRUE);
+
+	return status;
+}
+
+SR_PRIV int sr_gpio_get_value(int gpio)
+{
+	FILE *fd;
+	GString *path;
+	int ret, status;
+
+	path = g_string_sized_new(128);
+	g_string_printf(path, "/sys/class/gpio/gpio%d/value", gpio);
+	fd = g_fopen(path->str, "r");
+	if (!fd) {
+		sr_err("error opening %s: %s", path->str, strerror(errno));
+		g_string_free(path, TRUE);
+		return -1;
+	}
+
+	status = fscanf(fd, "%d", &ret);
+	fclose(fd);
+	if (status != 1) {
+		sr_err("error reading from %s: %s", path, strerror(errno));
+		g_string_free(path, TRUE);
+		return -1;
+	}
+
+	g_string_free(path, TRUE);
+	return ret;
+}
+
+SR_PRIV int sr_gpio_setval_export(int gpio, int value)
+{
+	int status;
+
+	status = sr_gpio_export(gpio);
+	if (status < 0)
+		return status;
+
+	status = sr_gpio_set_direction(gpio, GPIO_DIR_OUT);
+	if (status < 0)
+		return status;
+
+	status = sr_gpio_set_value(gpio, value);
+	if (status < 0)
+		return status;
+
+	return 0;
+}
+
+SR_PRIV int sr_gpio_getval_export(int gpio)
+{
+	int status;
+
+	status = sr_gpio_export(gpio);
+	if (status < 0)
+		return status;
+
+	status = sr_gpio_set_direction(gpio, GPIO_DIR_IN);
+	if (status < 0)
+		return status;
+
+	return sr_gpio_get_value(gpio);
+}

src/hardware/baylibre-acme/gpio.h

@@ -0,0 +1,41 @@
+/*
+ * This file is part of the libsigrok project.
+ *
+ * Copyright (C) 2015 Bartosz Golaszewski <bgolaszewski@baylibre.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * Linux-specific GPIO interface helpers. These functions could be moved out
+ * of this directory if any other driver would happen to want to use them.
+ */
+
+#ifndef LIBSIGROK_GPIO_H
+#define LIBSIGROK_GPIO_H
+
+enum {
+	GPIO_DIR_IN,
+	GPIO_DIR_OUT,
+};
+
+SR_PRIV int sr_gpio_export(unsigned gpio);
+SR_PRIV int sr_gpio_set_direction(unsigned gpio, unsigned direction);
+SR_PRIV int sr_gpio_set_value(unsigned gpio, unsigned value);
+SR_PRIV int sr_gpio_get_value(int gpio);
+/* These functions export given gpio if it's not already exported. */
+SR_PRIV int sr_gpio_setval_export(int gpio, int value);
+SR_PRIV int sr_gpio_getval_export(int gpio);
+
+#endif /* LIBSIGROK_GPIO_H */