dpll: zl3073x: add per-DPLL serialization lock

Add a per-DPLL mutex that serializes all operations on a given DPLL
channel across DPLL netlink callbacks, the periodic kthread worker,
and (in subsequent patches) PTP clock callbacks.

All DPLL pin and device callbacks that access mutable state take the
lock as the first operation. The periodic worker holds it for the
entire check cycle of each channel, deferring change notifications
until after the lock is released to avoid ABBA deadlock with
dpll_lock. This establishes the lock ordering:
dpll_lock (subsystem, outer) -> zldpll->lock (driver, inner).

Move zl3073x_chan_state_update() from the per-device
zl3073x_dev_chan_states_update() loop into the per-DPLL
zl3073x_dpll_changes_check() so it runs under zldpll->lock.
This serializes df_offset writes with all readers and
eliminates the need for separate df_offset synchronization.

Change pin->freq_offset from atomic64_t to plain s64 since all
readers and writers are now serialized by zldpll->lock, making
atomic access unnecessary.

Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Reviewed-by: Petr Oros <poros@redhat.com>
Link: https://patch.msgid.link/20260630125536.720717-5-ivecera@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

0 files changed, 0 insertions, 0 deletions