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Diffstat (limited to 'Documentation/driver-api/driver-model/device.rst')
| -rw-r--r-- | Documentation/driver-api/driver-model/device.rst | 27 |
1 files changed, 19 insertions, 8 deletions
diff --git a/Documentation/driver-api/driver-model/device.rst b/Documentation/driver-api/driver-model/device.rst index 2b868d49d349..0833be568b06 100644 --- a/Documentation/driver-api/driver-model/device.rst +++ b/Documentation/driver-api/driver-model/device.rst @@ -50,10 +50,10 @@ Attributes Attributes of devices can be exported by a device driver through sysfs. -Please see Documentation/filesystems/sysfs.txt for more information +Please see Documentation/filesystems/sysfs.rst for more information on how sysfs works. -As explained in Documentation/kobject.txt, device attributes must be +As explained in Documentation/core-api/kobject.rst, device attributes must be created before the KOBJ_ADD uevent is generated. The only way to realize that is by defining an attribute group. @@ -63,8 +63,14 @@ Attributes are declared using a macro called DEVICE_ATTR:: Example::: - static DEVICE_ATTR(type, 0444, show_type, NULL); - static DEVICE_ATTR(power, 0644, show_power, store_power); + static DEVICE_ATTR(type, 0444, type_show, NULL); + static DEVICE_ATTR(power, 0644, power_show, power_store); + +Helper macros are available for common values of mode, so the above examples +can be simplified to::: + + static DEVICE_ATTR_RO(type); + static DEVICE_ATTR_RW(power); This declares two structures of type struct device_attribute with respective names 'dev_attr_type' and 'dev_attr_power'. These two attributes can be @@ -76,19 +82,24 @@ organized as follows into a group:: NULL, }; - static struct attribute_group dev_attr_group = { + static struct attribute_group dev_group = { .attrs = dev_attrs, }; - static const struct attribute_group *dev_attr_groups[] = { - &dev_attr_group, + static const struct attribute_group *dev_groups[] = { + &dev_group, NULL, }; +A helper macro is available for the common case of a single group, so the +above two structures can be declared using::: + + ATTRIBUTE_GROUPS(dev); + This array of groups can then be associated with a device by setting the group pointer in struct device before device_register() is invoked:: - dev->groups = dev_attr_groups; + dev->groups = dev_groups; device_register(dev); The device_register() function will use the 'groups' pointer to create the |