driver-core: implement 'sysdev' functionality for regular devices and buses

All sysdev classes and sysdev devices will converted to regular devices
and buses to properly hook userspace into the event processing.

There is no interesting difference between a 'sysdev' and 'device' which
would justify to roll an entire own subsystem with different userspace
export semantics. Userspace relies on events and generic sysfs subsystem
infrastructure from sysdev devices, which are currently not properly
available.

Every converted sysdev class will create a regular device with the class
name in /sys/devices/system and all registered devices will becom a children
of theses devices.

For compatibility reasons, the sysdev class-wide attributes are created
at this parent device. (Do not copy that logic for anything new, subsystem-
wide properties belong to the subsystem, not to some fake parent device
created in /sys/devices.)

Every sysdev driver is implemented as a simple subsystem interface now,
and no longer called a driver.

After all sysdev classes are ported to regular driver core entities, the
sysdev implementation will be entirely removed from the kernel.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 74 insertions, 4 deletions

diff --git a/include/linux/device.h b/include/linux/device.h
index 341fb740d851..7f9fc1505e94 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -53,6 +53,8 @@ extern void bus_remove_file(struct bus_type *, struct bus_attribute *);
  * struct bus_type - The bus type of the device
  *
  * @name:       The name of the bus.
+ * @dev_name:   Used for subsystems to enumerate devices like ("foo%u", dev->id).
+ * @dev_root:   Default device to use as the parent.
  * @bus_attrs:  Default attributes of the bus.
  * @dev_attrs:  Default attributes of the devices on the bus.
  * @drv_attrs:  Default attributes of the device drivers on the bus.
@@ -86,6 +88,8 @@ extern void bus_remove_file(struct bus_type *, struct bus_attribute *);
  */
 struct bus_type {
         const char              *name;
+        const char              *dev_name;
+        struct device           *dev_root;
         struct bus_attribute    *bus_attrs;
         struct device_attribute *dev_attrs;
         struct driver_attribute *drv_attrs;
@@ -106,12 +110,30 @@ struct bus_type {
         struct subsys_private *p;
 };
 
-extern int __must_check bus_register(struct bus_type *bus);
+/* This is a #define to keep the compiler from merging different
+ * instances of the __key variable */
+#define bus_register(subsys)                    \
+({                                              \
+        static struct lock_class_key __key;     \
+        __bus_register(subsys, &__key); \
+})
+extern int __must_check __bus_register(struct bus_type *bus,
+                                       struct lock_class_key *key);
 extern void bus_unregister(struct bus_type *bus);
 
 extern int __must_check bus_rescan_devices(struct bus_type *bus);
 
 /* iterator helpers for buses */
+struct subsys_dev_iter {
+        struct klist_iter               ki;
+        const struct device_type        *type;
+};
+void subsys_dev_iter_init(struct subsys_dev_iter *iter,
+                         struct bus_type *subsys,
+                         struct device *start,
+                         const struct device_type *type);
+struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter);
+void subsys_dev_iter_exit(struct subsys_dev_iter *iter);
 
 int bus_for_each_dev(struct bus_type *bus, struct device *start, void *data,
                      int (*fn)(struct device *dev, void *data));
@@ -121,10 +143,10 @@ struct device *bus_find_device(struct bus_type *bus, struct device *start,
 struct device *bus_find_device_by_name(struct bus_type *bus,
                                        struct device *start,
                                        const char *name);
-
+struct device *subsys_find_device_by_id(struct bus_type *bus, unsigned int id,
+                                        struct device *hint);
 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
                      void *data, int (*fn)(struct device_driver *, void *));
-
 void bus_sort_breadthfirst(struct bus_type *bus,
                            int (*compare)(const struct device *a,
                                           const struct device *b));
@@ -256,6 +278,33 @@ struct device *driver_find_device(struct device_driver *drv,
                                   int (*match)(struct device *dev, void *data));
 
 /**
+ * struct subsys_interface - interfaces to device functions
+ * @name        name of the device function
+ * @subsystem   subsytem of the devices to attach to
+ * @node        the list of functions registered at the subsystem
+ * @add         device hookup to device function handler
+ * @remove      device hookup to device function handler
+ *
+ * Simple interfaces attached to a subsystem. Multiple interfaces can
+ * attach to a subsystem and its devices. Unlike drivers, they do not
+ * exclusively claim or control devices. Interfaces usually represent
+ * a specific functionality of a subsystem/class of devices.
+ */
+struct subsys_interface {
+        const char *name;
+        struct bus_type *subsys;
+        struct list_head node;
+        int (*add_dev)(struct device *dev, struct subsys_interface *sif);
+        int (*remove_dev)(struct device *dev, struct subsys_interface *sif);
+};
+
+int subsys_interface_register(struct subsys_interface *sif);
+void subsys_interface_unregister(struct subsys_interface *sif);
+
+int subsys_system_register(struct bus_type *subsys,
+                           const struct attribute_group **groups);
+
+/**
  * struct class - device classes
  * @name:       Name of the class.
  * @owner:      The module owner.
@@ -438,8 +487,28 @@ struct device_attribute {
                          const char *buf, size_t count);
 };
 
+struct dev_ext_attribute {
+        struct device_attribute attr;
+        void *var;
+};
+
+ssize_t device_show_ulong(struct device *dev, struct device_attribute *attr,
+                          char *buf);
+ssize_t device_store_ulong(struct device *dev, struct device_attribute *attr,
+                           const char *buf, size_t count);
+ssize_t device_show_int(struct device *dev, struct device_attribute *attr,
+                        char *buf);
+ssize_t device_store_int(struct device *dev, struct device_attribute *attr,
+                         const char *buf, size_t count);
+
 #define DEVICE_ATTR(_name, _mode, _show, _store) \
-struct device_attribute dev_attr_##_name = __ATTR(_name, _mode, _show, _store)
+        struct device_attribute dev_attr_##_name = __ATTR(_name, _mode, _show, _store)
+#define DEVICE_ULONG_ATTR(_name, _mode, _var) \
+        struct dev_ext_attribute dev_attr_##_name = \
+                { __ATTR(_name, _mode, device_show_ulong, device_store_ulong), &(_var) }
+#define DEVICE_INT_ATTR(_name, _mode, _var) \
+        struct dev_ext_attribute dev_attr_##_name = \
+                { __ATTR(_name, _mode, device_show_ulong, device_store_ulong), &(_var) }
 
 extern int __must_check device_create_file(struct device *device,
                                         const struct device_attribute *entry);
@@ -603,6 +672,7 @@ struct device {
         struct device_node      *of_node; /* associated device tree node */
 
         dev_t                   devt;   /* dev_t, creates the sysfs "dev" */
+        u32                     id;     /* device instance */
 
         spinlock_t              devres_lock;
         struct list_head        devres_head;