faf3aa7c22
It is vital to denote the file name and summary for each source, otherwise readers could not figure out the corresponding files.
66 lines
1.5 KiB
C
66 lines
1.5 KiB
C
/*
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* hello-sysfs.c sysfs example
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*/
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/kobject.h>
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#include <linux/module.h>
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#include <linux/string.h>
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#include <linux/sysfs.h>
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MODULE_LICENSE("GPL");
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static struct kobject *mymodule;
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/* the variable you want to be able to change */
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static int myvariable = 0;
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static ssize_t myvariable_show(struct kobject *kobj,
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struct kobj_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%d\n", myvariable);
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}
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static ssize_t myvariable_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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char *buf,
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size_t count)
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{
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sscanf(buf, "%du", &myvariable);
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return count;
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}
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static struct kobj_attribute myvariable_attribute =
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__ATTR(myvariable, 0660, myvariable_show, (void *) myvariable_store);
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static int __init mymodule_init(void)
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{
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int error = 0;
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pr_info("mymodule: initialised\n");
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mymodule = kobject_create_and_add("mymodule", kernel_kobj);
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if (!mymodule)
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return -ENOMEM;
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error = sysfs_create_file(mymodule, &myvariable_attribute.attr);
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if (error) {
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pr_info(
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"failed to create the myvariable file "
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"in /sys/kernel/mymodule\n");
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}
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return error;
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}
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static void __exit mymodule_exit(void)
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{
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pr_info("mymodule: Exit success\n");
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kobject_put(mymodule);
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}
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module_init(mymodule_init);
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module_exit(mymodule_exit);
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