1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Intel MIC Platform Software Stack (MPSS)
4 *
5 * Copyright(c) 2013 Intel Corporation.
6 *
7 * Intel MIC User Space Tools.
8 */
9
10 #include "mpssd.h"
11
12 #define PAGE_SIZE 4096
13
14 char *
readsysfs(char * dir,char * entry)15 readsysfs(char *dir, char *entry)
16 {
17 char filename[PATH_MAX];
18 char value[PAGE_SIZE];
19 char *string = NULL;
20 int fd;
21 int len;
22
23 if (dir == NULL)
24 snprintf(filename, PATH_MAX, "%s/%s", MICSYSFSDIR, entry);
25 else
26 snprintf(filename, PATH_MAX,
27 "%s/%s/%s", MICSYSFSDIR, dir, entry);
28
29 fd = open(filename, O_RDONLY);
30 if (fd < 0) {
31 mpsslog("Failed to open sysfs entry '%s': %s\n",
32 filename, strerror(errno));
33 return NULL;
34 }
35
36 len = read(fd, value, sizeof(value));
37 if (len < 0) {
38 mpsslog("Failed to read sysfs entry '%s': %s\n",
39 filename, strerror(errno));
40 goto readsys_ret;
41 }
42 if (len == 0)
43 goto readsys_ret;
44
45 value[len - 1] = '\0';
46
47 string = malloc(strlen(value) + 1);
48 if (string)
49 strcpy(string, value);
50
51 readsys_ret:
52 close(fd);
53 return string;
54 }
55
56 int
setsysfs(char * dir,char * entry,char * value)57 setsysfs(char *dir, char *entry, char *value)
58 {
59 char filename[PATH_MAX];
60 char *oldvalue;
61 int fd, ret = 0;
62
63 if (dir == NULL)
64 snprintf(filename, PATH_MAX, "%s/%s", MICSYSFSDIR, entry);
65 else
66 snprintf(filename, PATH_MAX, "%s/%s/%s",
67 MICSYSFSDIR, dir, entry);
68
69 oldvalue = readsysfs(dir, entry);
70
71 fd = open(filename, O_RDWR);
72 if (fd < 0) {
73 ret = errno;
74 mpsslog("Failed to open sysfs entry '%s': %s\n",
75 filename, strerror(errno));
76 goto done;
77 }
78
79 if (!oldvalue || strcmp(value, oldvalue)) {
80 if (write(fd, value, strlen(value)) < 0) {
81 ret = errno;
82 mpsslog("Failed to write new sysfs entry '%s': %s\n",
83 filename, strerror(errno));
84 }
85 }
86 close(fd);
87 done:
88 if (oldvalue)
89 free(oldvalue);
90 return ret;
91 }
92
