Add the basic sudoku subsystem and sudoku_type

ksudoku.c

@@ -8,6 +8,49 @@ static MATRIX_ATTR_RO(is_valid);
 static MATRIX_ATTR_RO(is_solved);
 
 
+/**
+ * sudoku_create_file - create sysfs attribute file for the given sudoku.
+ * @sudoku: sudoku
+ * @attr: sudoku attribute descriptor.
+ */
+int sudoku_create_file(struct sudoku *s,
+		       const struct matrix_attribute *attr)
+{
+	int error = 0;
+
+	if (s) {
+		WARN(((attr->attr.mode & S_IWUGO) && !attr->store),
+			"Attribute %s: write permission without 'store'\n",
+			attr->attr.name);
+		WARN(((attr->attr.mode & S_IRUGO) && !attr->show),
+			"Attribute %s: read permission without 'show'\n",
+			attr->attr.name);
+		error = sysfs_create_file(&s->kobj, &attr->attr);
+	}
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(sudoku_create_file);
+
+
+static ssize_t is_valid_show(struct kobject *kobj, struct attribute *attr,
+                             char *buf)
+{
+        struct sudoku_attribute *s_attr = to_sudoku_attr(attr);
+        struct sudoku *s = to_sudoku(kobj);
+        ssize_t ret = -EIO;
+
+        if (s_attr->show)
+                ret = s_attr->show(s, s_attr, buf);
+
+        if (ret >= (ssize_t)PAGE_SIZE) {
+                printk("is_valid_show: %pS returned bad count\n",
+                       s_attr->show);
+        }
+        return ret;
+}
+
+
 static int kstudy_init(void)
 {
         printk(KERN_ALERT "Init ksudoku.\n");

ksudoku.h

@@ -4,21 +4,49 @@
 #include <linux/module.h>
 #include <linux/sysfs.h>
 
-ssize_t is_valid_show(void);
-ssize_t is_valid_store(void);
+#define to_sudoku(obj) container_of(obj, struct sudoku, kobj)
+#define to_sudoku_attr(_attr) container_of(_attr, struct sudoku_attribute, attr)
+
+struct sudoku;
+
+static ssize_t is_valid_show(struct kobject *kobj, struct attribute *attr,
+                             char *buf)
+static ssize_t is_valid_store(void);
+
+static ssize_t is_solved_show(struct kobject *kobj, struct attribute *attr,
+                              char *buf);
+static ssize_t is_solved_store(void);
 
-ssize_t is_solved_show(void);
-ssize_t is_solved_store(void);
 
 struct matrix_attribute {
 	struct attribute attr;
-	ssize_t (*show)(void);
+	ssize_t (*show)(struct kobject *kobj, struct attribute *attr,
+                        char *buf);
 	ssize_t (*store)(void);
         bool value;
 };
 
-struct matrix {
+/*
+ * The type of sudoku, "struct sudoku" is embedded in. A class
+ * or bus can only contain one sudoku type.
+ * This identifies the sudoku type and carries type-specific
+ * information, equivalent to the kobj_type of a kobject.
+ * Since we have only one type it always will be the same button
+ * we're designing a subsystem so we have to make sysfs happy.
+ * If "name" is specified, the uevent will contain it in
+ * the DEVTYPE variable.
+ */
+struct sudoku_type {
+	const char *name;
         char matrix[81];
+
+	const struct attribute_group **groups;
+	int (*uevent)(struct sudoku *s, struct kobj_uevent_env *env);
+	char *(*devnode)(struct sudoku *s, umode_t *mode,
+			 kuid_t *uid, kgid_t *gid);
+	void (*release)(struct sudoku *s);
+
+        const struct sysfs_ops *sysfs_ops;
 };
 
 #define MATRIX_ATTR_RO(_name) \
@@ -27,4 +55,6 @@ struct matrix {
 #define MATRIX_ATTR_WO(_name) \
 	struct matrix_attribute matrix_##_name = __ATTR_WO(_name)
 
+extern int sudoku_create_file(struct sudoku *s,
+                              const struct matrix_attribute *attr)
 #endif