This patch series introduces new hwmon API functions hwmon_device_register_with_groups() and devm_hwmon_device_register_with_groups(). hwmon_device_register_with_groups() lets callers register hwmon devices as well as associated sysfs attributes with a single call. This simplifies hwmon device registration and avoids potential race conditions seen if sysfs attributes are created after the initial hwmon device was registered. devm_hwmon_device_register_with_groups() is the managed version of the same function. The rationale for the new API is that sysfs attributes should be created synchronously with device creation to avoid race conditions, as outlined in http://www.linuxfoundation.org/news-media/blogs/browse/2013/06/how-create-sysfs-file-correctly. The first patch of the series introduces hwmon_device_register_with_groups(). Patches 2 to 6 convert some hwmon drivers to use the new API to show and test its use. Only the ds1621 and nct6775 patches have been tested at this time; the others are informational to show the potential of the new functions. Patch 7 introduces devm_hwmon_device_register_with_groups() and the matching function devm_hwmon_device_unregister(). Patch 8 and 9 convert the nct6775 and ds1621 drivers drivers to use this function. hwmon attributes The old hwmon API attaches hwmon attributes to the parent device, not to the hwmon device itself. With the new API, hwmon attributes are attached to the hwmon device itself. Handling the 'name' attribute for hwmon drivers Since sysfs attributes are no longer attached to the parent device, the mandatory 'name' attribute has to be created explicitly. For some drivers, this was already the case. I2c drivers, however, create the 'name' attribute in the i2c core, and it was used by the hwmon driver. To simplify name attribute handling, the value of the 'name' attribute is passed as parameter to hwmon_device_register_with_groups(). The hwmon core creates and manages the attribute. If a NULL pointer is passed instead of a name, the attribute is not created. Unfortunately, since we need a variable to store the pointer to 'name', it was necessary to create an internal 'struct hwmon_device'. For this reason, device_create(), or rather device_create_with_groups() can no longer be used to create the actual device. device_register() is used instead, and the device data structures are managed locally. [ If there is a better solution for this problem, I am listening. ] The series is based on my hwmon-next branch and should apply to the top of linux-next. --------- v2: Rename API functions device_create_groups -> device_create_with_groups hwmon_device_register_groups -> hwmon_device_register_with_groups Additional parameter 'void *drvdata' for hwmon_device_register_groups. Additional parameter 'name' for hwmon_device_register_groups. Introduce devm_hwmon_device_register_with_groups(). Various fixes in hwmon driver conversions. _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
