From 6d3b1c216f28162019e0ee1f539192f7ee2204ed Mon Sep 17 00:00:00 2001
From: Andrey Tarasov <kochenevo@gmail.com>
Date: Fri, 14 Feb 2020 15:06:30 +0700
Subject: [PATCH] Add sysfs module

---
 mydev/devfile.c |  4 ++-
 sysfs/Makefile  | 13 ++++++++
 sysfs/sysfs.c   | 86 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 102 insertions(+), 1 deletion(-)
 create mode 100644 sysfs/Makefile
 create mode 100644 sysfs/sysfs.c

diff --git a/mydev/devfile.c b/mydev/devfile.c
index 29bad25..55651b1 100644
--- a/mydev/devfile.c
+++ b/mydev/devfile.c
@@ -8,7 +8,6 @@
 #include <linux/init.h>
 #include <linux/fs.h>
 #include <linux/time.h>
-#include <linux/fs.h>
 #include <linux/string.h>
 #include <asm/uaccess.h>
 #include "devfile.h"
@@ -42,6 +41,9 @@ static int __init setup_device(void)
 	}
 
 	printk(KERN_INFO "Device registered with major number %d\n", major_num);
+	printk(KERN_INFO "Create a dev file with:\n");
+	printk(KERN_INFO "mknod /dev/%s c %d 0\n", DEVICE_NAME, major_num);
+
 	return 0;
 }
 
diff --git a/sysfs/Makefile b/sysfs/Makefile
new file mode 100644
index 0000000..e6518e1
--- /dev/null
+++ b/sysfs/Makefile
@@ -0,0 +1,13 @@
+PWD := $(shell pwd)
+obj-m += sysfs.o
+KDIR := /home/and/sources/linux-5.3.13
+ccflags-y := -std=gnu99 -Wno-declaration-after-statement
+
+
+all:
+	make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- -C ${KDIR} M=$(PWD) modules
+
+clean:
+	make -C ${KDIR} M=$(PWD) clean
+
+
diff --git a/sysfs/sysfs.c b/sysfs/sysfs.c
new file mode 100644
index 0000000..03dc00c
--- /dev/null
+++ b/sysfs/sysfs.c
@@ -0,0 +1,86 @@
+/*
+ * sysfs.c: взаимодействие между ядром и пространством пользователя
+ * через виртуальную файловую систему sysfs
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include<linux/sysfs.h>
+#include<linux/kobject.h>
+
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Andrey Tarasov");
+MODULE_DESCRIPTION("Test module for sysfs");
+
+// Размер буфера
+#define BUF_SIZE	1024
+
+// Имя директории в sysfs
+#define KOBJ_DIR_NAME	"test"
+
+// Имя атрибута/файла в sysfs
+#define KOBJ_FILE_NAME	message
+
+
+// Буфер для ввода/вывода данных через sysfs
+static char kbuffer[BUF_SIZE] = "Hello from sysfs!\n";
+
+static struct kobject *kobjp;
+
+/*
+ * sysfs_read - вывод данных из буфера в userspace через sysfs
+ */
+static ssize_t sysfs_read(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+	printk(KERN_INFO "Reading sysfs\n");
+	return sprintf(buf, "%s", kbuffer);
+}
+
+/*
+ * sysfs_write - ввод данных в буфер из userspace через sysfs
+ */
+static ssize_t sysfs_write(struct kobject *kobj, struct kobj_attribute *attr,const char *buf, size_t count)
+{
+	printk(KERN_INFO "Writing to sysfs\n");
+	strncpy(kbuffer, buf, count);
+	kbuffer[count] = 0;
+	return count;
+}
+
+
+static struct kobj_attribute sysfs_attr = __ATTR(KOBJ_FILE_NAME, 0660, sysfs_read, sysfs_write);
+
+/*
+ * setup_module - инициализация модуля
+ */
+static int __init setup_module(void)
+{
+	kobjp = kobject_create_and_add(KOBJ_DIR_NAME, kernel_kobj);
+	if (! kobjp)
+		return -ENOMEM;
+
+	if (sysfs_create_file(kobjp, &sysfs_attr.attr)) {
+		printk(KERN_INFO "Can't create sysfs file\n");
+		kobject_put(kobjp);
+	} else
+		printk(KERN_INFO "Created sysfs entry /sys/kernel/%s/%s\n", KOBJ_DIR_NAME, __stringify(KOBJ_FILE_NAME));
+
+	return 0;
+}
+
+/*
+ * shutdown_module - закрытие модуля
+ */
+static void __exit shutdown_module(void)
+{
+	kobject_put(kobjp);
+	printk(KERN_INFO "Sysfs object deleted\n");
+}
+
+
+module_init(setup_module);
+module_exit(shutdown_module);
+