sysdev: Add utility functions for simple int/ulong variable sysdev attributes

This adds a new sysdev_ext_attribute that stores a pointer to the variable
it manages and some utility functions/macro to easily use them.

Previously all users wrote custom macros to generate show/store
functions for each variable, with this it is possible to avoid
that in many cases.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 83 insertions, 0 deletions

diff --git a/drivers/base/sys.c b/drivers/base/sys.c
index dc7dace14e1c..40fc14f03540 100644
--- a/drivers/base/sys.c
+++ b/drivers/base/sys.c
@@ -479,3 +479,52 @@ int __init system_bus_init(void)
 
 EXPORT_SYMBOL_GPL(sysdev_register);
 EXPORT_SYMBOL_GPL(sysdev_unregister);
+
+#define to_ext_attr(x) container_of(x, struct sysdev_ext_attribute, attr)
+
+ssize_t sysdev_store_ulong(struct sys_device *sysdev,
+                           struct sysdev_attribute *attr,
+                           const char *buf, size_t size)
+{
+        struct sysdev_ext_attribute *ea = to_ext_attr(attr);
+        char *end;
+        unsigned long new = simple_strtoul(buf, &end, 0);
+        if (end == buf)
+                return -EINVAL;
+        *(unsigned long *)(ea->var) = new;
+        return end - buf;
+}
+EXPORT_SYMBOL_GPL(sysdev_store_ulong);
+
+ssize_t sysdev_show_ulong(struct sys_device *sysdev,
+                          struct sysdev_attribute *attr,
+                          char *buf)
+{
+        struct sysdev_ext_attribute *ea = to_ext_attr(attr);
+        return snprintf(buf, PAGE_SIZE, "%lx\n", *(unsigned long *)(ea->var));
+}
+EXPORT_SYMBOL_GPL(sysdev_show_ulong);
+
+ssize_t sysdev_store_int(struct sys_device *sysdev,
+                           struct sysdev_attribute *attr,
+                           const char *buf, size_t size)
+{
+        struct sysdev_ext_attribute *ea = to_ext_attr(attr);
+        char *end;
+        long new = simple_strtol(buf, &end, 0);
+        if (end == buf || new > INT_MAX || new < INT_MIN)
+                return -EINVAL;
+        *(int *)(ea->var) = new;
+        return end - buf;
+}
+EXPORT_SYMBOL_GPL(sysdev_store_int);
+
+ssize_t sysdev_show_int(struct sys_device *sysdev,
+                          struct sysdev_attribute *attr,
+                          char *buf)
+{
+        struct sysdev_ext_attribute *ea = to_ext_attr(attr);
+        return snprintf(buf, PAGE_SIZE, "%d\n", *(int *)(ea->var));
+}
+EXPORT_SYMBOL_GPL(sysdev_show_int);
+
diff --git a/include/linux/sysdev.h b/include/linux/sysdev.h
index 8dcf3162b21b..f395bb3fa2f2 100644
--- a/include/linux/sysdev.h
+++ b/include/linux/sysdev.h
@@ -119,4 +119,38 @@ struct sysdev_attribute {
 extern int sysdev_create_file(struct sys_device *, struct sysdev_attribute *);
 extern void sysdev_remove_file(struct sys_device *, struct sysdev_attribute *);
 
+struct sysdev_ext_attribute {
+        struct sysdev_attribute attr;
+        void *var;
+};
+
+/*
+ * Support for simple variable sysdev attributes.
+ * The pointer to the variable is stored in a sysdev_ext_attribute
+ */
+
+/* Add more types as needed */
+
+extern ssize_t sysdev_show_ulong(struct sys_device *, struct sysdev_attribute *,
+                                char *);
+extern ssize_t sysdev_store_ulong(struct sys_device *,
+                        struct sysdev_attribute *, const char *, size_t);
+extern ssize_t sysdev_show_int(struct sys_device *, struct sysdev_attribute *,
+                                char *);
+extern ssize_t sysdev_store_int(struct sys_device *,
+                        struct sysdev_attribute *, const char *, size_t);
+
+#define _SYSDEV_ULONG_ATTR(_name, _mode, _var)                          \
+        { _SYSDEV_ATTR(_name, _mode, sysdev_show_ulong, sysdev_store_ulong), \
+          &(_var) }
+#define SYSDEV_ULONG_ATTR(_name, _mode, _var)                   \
+        struct sysdev_ext_attribute attr_##_name =              \
+                _SYSDEV_ULONG_ATTR(_name, _mode, _var);
+#define _SYSDEV_INT_ATTR(_name, _mode, _var)                            \
+        { _SYSDEV_ATTR(_name, _mode, sysdev_show_int, sysdev_store_int), \
+          &(_var) }
+#define SYSDEV_INT_ATTR(_name, _mode, _var)                     \
+        struct sysdev_ext_attribute attr_##_name =              \
+                _SYSDEV_INT_ATTR(_name, _mode, _var);
+
 #endif /* _SYSDEV_H_ */