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

Thu May 26 14:36:09 UTC 2016

On Thu, May 26, 2016 at 03:14:29PM +0100, Chris Wilson wrote:
> 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");

That's goint to limit this to i915. I was thinking we could pass
the drm_fd here to find the correct minor for it.

Maybe drmGetDeviceNameFromFd() is the right thing for that?

> +		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);

EINTR?

> +	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) {

EINTR?

> +		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
> 
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-- 
Ville Syrjälä
Intel OTC