[Intel-gfx] [PATCH igt 1/2] lib: Add simple sysfs accessors

[Chris Wilson]

igt_sysfs_set() for setting an attribute via sysfs, igt_sysfs_get() for
reading.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 lib/Makefile.sources |   2 +
 lib/igt_sysfs.c      | 145 +++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_sysfs.h      |  33 ++++++++++++
 3 files changed, 180 insertions(+)
 create mode 100644 lib/igt_sysfs.c
 create mode 100644 lib/igt_sysfs.h

diff --git a/lib/Makefile.sources b/lib/Makefile.sources
index 1316fd2..f50ff4d 100644
--- a/lib/Makefile.sources
+++ b/lib/Makefile.sources
@@ -16,6 +16,8 @@ libintel_tools_la_SOURCES = 	\
 	igt_gt.h		\
 	igt_stats.c		\
 	igt_stats.h		\
+	igt_sysfs.c		\
+	igt_sysfs.h		\
 	instdone.c		\
 	instdone.h		\
 	intel_batchbuffer.c	\
diff --git a/lib/igt_sysfs.c b/lib/igt_sysfs.c
new file mode 100644
index 0000000..4dd6089
--- /dev/null
+++ b/lib/igt_sysfs.c
@@ -0,0 +1,145 @@
+/*
+ * Copyright © 2016 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#include <inttypes.h>
+#include <sys/stat.h>
+#include <sys/mount.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <limits.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <i915_drm.h>
+
+#include "igt_sysfs.h"
+
+typedef struct {
+	int dir;
+} igt_sysfs_t;
+
+static int __igt_sysfs_init(void)
+{
+	char path[1024];
+	struct stat st;
+
+	for (int n = 0; n < 16; n++) {
+		int len = sprintf(path, "/sys/class/drm/card%d", n);
+		sprintf(path + len, "/error");
+		if (stat(path, &st) == 0) {
+			path[len] = '\0';
+			return open(path, O_RDONLY);
+		}
+	}
+
+	return -1;
+}
+
+static int __igt_sysfs_singleton(void)
+{
+	static int sysfs = -1;
+
+	if (sysfs == -1)
+		sysfs = __igt_sysfs_init();
+
+	return sysfs;
+}
+
+/**
+ * igt_sysfs_set:
+ * @filename: name of the sysfs node to open
+ * @value: the string to write
+ *
+ * This writes the value to the sysfs file.
+ *
+ * Returns:
+ * True on success, false on failure.
+ */
+bool igt_sysfs_set(const char *filename, const char *value)
+{
+	int sysfs = __igt_sysfs_singleton();
+	int fd, len, ret;
+
+	if (sysfs < 0)
+		return false;
+
+	fd = openat(sysfs, filename, O_WRONLY);
+	if (fd < 0)
+		return false;
+
+	len = strlen(value);
+	ret = write(fd, value, len);
+	close(fd);
+
+	return len == ret;
+}
+
+/**
+ * igt_sysfs_get:
+ * @filename: name of the sysfs node to open
+ *
+ * This reads the value from the sysfs file.
+ *
+ * Returns:
+ * A nul-terminated string, must be freed by caller after use, or NULL
+ * on failure.
+ */
+char *igt_sysfs_get(const char *filename)
+{
+	int sysfs = __igt_sysfs_singleton();
+	char *buf;
+	int len, offset, rem;
+	int ret, fd;
+
+	if (sysfs < 0)
+		return NULL;
+
+	fd = openat(sysfs, filename, O_WRONLY);
+	if (fd < 0)
+		return NULL;
+
+	offset = 0;
+	len = 64;
+	rem =  len - offset - 1;
+	buf = malloc(len);
+	if (!buf)
+		return NULL;
+
+	while ((ret = read(fd, buf + offset, rem)) == rem) {
+		char *newbuf;
+
+		len *= 2;
+		offset += ret;
+
+		newbuf = realloc(buf, len);
+		if (!newbuf)
+			break;
+
+		rem = len - offset - 1;
+	}
+
+	buf[offset] = '0';
+	return buf;
+}
diff --git a/lib/igt_sysfs.h b/lib/igt_sysfs.h
new file mode 100644
index 0000000..48c218d
--- /dev/null
+++ b/lib/igt_sysfs.h
@@ -0,0 +1,33 @@
+/*
+ * Copyright © 2016 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#ifndef __IGT_SYSFS_H__
+#define __IGT_SYSFS_H__
+
+#include <stdbool.h>
+
+bool igt_sysfs_set(const char *filename, const char *value);
+char *igt_sysfs_get(const char *filename);
+
+#endif /* __IGT_SYSFS_H__ */
-- 
2.8.1