[PATCH v4 0/1] hwmon: (applesmc) Convert to hwmon_device_register_with_info

[Shih-Yuan Lee <fourdollars@debian.org>]

Hi Guenter, Armin, and Henrik,

This is v4 of the patch series converting the applesmc driver from using
the deprecated hwmon_device_register() function to the modern
hwmon_device_register_with_info() API.

Changes in v4:
- Convert to devres-managed devm_hwmon_device_register_with_info() to fix
  a lifetime Use-After-Free mismatch when the driver is unbound via sysfs
  (releasing devres-managed attributes memory while keeping the hwmon
  sysfs files active).
- Declare hwmon_dev locally in applesmc_init() and remove it from the
  global static variables, and clean up the redundant manual
  hwmon_device_unregister() call in applesmc_exit().

Changes in v3:
- Fix a recursive mutex deadlock in applesmc_hwmon_write() when writing
  to pwmX_enable by using applesmc_get_entry_by_key() to resolve the entry
  locklessly and then calling the underlying raw read_smc/write_smc
  functions directly under the mutex lock.
- Fix a fallback fan label truncation bug by pre-padding the generated fallback
  string with four spaces so that the "+ 4" pointer arithmetic offset yields the
  correct label "Fan %d".

Changes in v2:
- Abandon the minimal dummy registration approach in v1.
- Fully convert the driver to modern HWMON ABI standards by dynamically
  allocating temp and fan channels at initialization.
- Rename legacy non-standard attributes to comply with the standard HWMON ABI:
  - fanX_output -> fanX_target (HWMON_F_TARGET)
  - fanX_manual -> pwmX_enable (HWMON_PWM_ENABLE)
- Dynamically register the remaining non-standard fanX_safe attributes
  under HWMON class directory via extra_groups.
- Load and cache fan positions in smcreg.fan_positions to support returning
  labels by reference in .read_string.
- Clean up unused static attribute groups and show/store callback functions
  to avoid unused symbol compiler warnings.
- Verified compilation and successfully tested on real MacBook hardware.

We appreciate your review and comments on this refactoring.

Shih-Yuan Lee (1):
  hwmon: (applesmc) Convert to hwmon_device_register_with_info

 drivers/hwmon/applesmc.c | 467 ++++++++++++++++++++++++++-------------
 1 file changed, 316 insertions(+), 151 deletions(-)

-- 
2.39.5