dpll: zl3073x: Cache all reference properties in zl3073x_ref

[ Upstream commit 5bc02b1 ]

Expand the zl3073x_ref structure to cache all reference-related
hardware registers, including frequency components, embedded-sync
settings  and phase compensation. Previously, these registers were
read on-demand from various functions in dpll.c leading to frequent
mailbox operations.

Modify zl3073x_ref_state_fetch() to read and populate all these new
fields at once. Refactor all "getter" functions in dpll.c to read
from this new cached state instead of performing direct register
access.

Remove the standalone zl3073x_dpll_input_ref_frequency_get() helper,
as its functionality is now replaced by zl3073x_ref_freq_get() which
operates on the cached state and add a corresponding zl3073x_dev_...
wrapper.

Introduce a new function, zl3073x_ref_state_set(), to handle
writing changes back to the hardware. This function compares the
provided state with the current cached state and writes *only* the
modified register values to the device via a single mailbox sequence
before updating the local cache.

Refactor all dpll "setter" functions to modify a local copy of the
ref state and then call zl3073x_ref_state_set() to commit the changes.

As a cleanup, update callers in dpll.c that already have
a struct zl3073x_ref * to use the direct helpers instead of the
zl3073x_dev_... wrappers.

This change centralizes all reference-related register I/O into ref.c,
significantly reduces bus traffic, and simplifies the logic in dpll.c.

Reviewed-by: Petr Oros <poros@redhat.com>
Tested-by: Prathosh Satish <Prathosh.Satish@microchip.com>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Link: https://patch.msgid.link/20251113074105.141379-5-ivecera@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 4cfe066 ("dpll: zl3073x: fix REF_PHASE_OFFSET_COMP register width for some chip IDs")
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: ivecera

drivers/dpll/zl3073x/core.h

@@ -197,6 +197,21 @@ zl3073x_dev_ref_ffo_get(struct zl3073x_dev *zldev, u8 index)
 	return zl3073x_ref_ffo_get(ref);
 }
 
+/**
+ * zl3073x_dev_ref_freq_get - get input reference frequency
+ * @zldev: pointer to zl3073x device
+ * @index: input reference index
+ *
+ * Return: frequency of given input reference
+ */
+static inline u32
+zl3073x_dev_ref_freq_get(struct zl3073x_dev *zldev, u8 index)
+{
+	const struct zl3073x_ref *ref = zl3073x_ref_state_get(zldev, index);
+
+	return zl3073x_ref_freq_get(ref);
+}
+
 /**
  * zl3073x_dev_ref_is_diff - check if the given input reference is differential
  * @zldev: pointer to zl3073x device