dpll: add phase-adjust-gran pin attribute

Phase-adjust values are currently limited by a min-max range. Some
hardware requires, for certain pin types, that values be multiples of
a specific granularity, as in the zl3073x driver.

Add a `phase-adjust-gran` pin attribute and an appropriate field in
dpll_pin_properties. If set by the driver, use its value to validate
user-provided phase-adjust values.

Reviewed-by: Michal Schmidt <[e-mail]>
Reviewed-by: Petr Oros <[e-mail]>
Tested-by: Prathosh Satish <[e-mail]>
Signed-off-by: Ivan Vecera <[e-mail]>
Reviewed-by: Jiri Pirko <[e-mail]>
Reviewed-by: Arkadiusz Kubalewski <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

Documentation/driver-api/dpll.rst

···
   ================================== ======================================
 
 Device may also provide ability to adjust a signal phase on a pin.
-If pin phase adjustment is supported, minimal and maximal values that pin
-handle shall be provide to the user on ``DPLL_CMD_PIN_GET`` respond
-with ``DPLL_A_PIN_PHASE_ADJUST_MIN`` and ``DPLL_A_PIN_PHASE_ADJUST_MAX``
+If pin phase adjustment is supported, minimal and maximal values and
+granularity that pin handle shall be provided to the user on
+``DPLL_CMD_PIN_GET`` respond with ``DPLL_A_PIN_PHASE_ADJUST_MIN``,
+``DPLL_A_PIN_PHASE_ADJUST_MAX`` and ``DPLL_A_PIN_PHASE_ADJUST_GRAN``
 attributes. Configured phase adjust value is provided with
 ``DPLL_A_PIN_PHASE_ADJUST`` attribute of a pin, and value change can be
 requested with the same attribute with ``DPLL_CMD_PIN_SET`` command.
 
-  =============================== ======================================
-  ``DPLL_A_PIN_ID``               configured pin id
-  ``DPLL_A_PIN_PHASE_ADJUST_MIN`` attr minimum value of phase adjustment
-  ``DPLL_A_PIN_PHASE_ADJUST_MAX`` attr maximum value of phase adjustment
-  ``DPLL_A_PIN_PHASE_ADJUST``     attr configured value of phase
-                                  adjustment on parent dpll device
-  ``DPLL_A_PIN_PARENT_DEVICE``    nested attribute for requesting
-                                  configuration on given parent dpll
-                                  device
-    ``DPLL_A_PIN_PARENT_ID``      parent dpll device id
-    ``DPLL_A_PIN_PHASE_OFFSET``   attr measured phase difference
-                                  between a pin and parent dpll device
-  =============================== ======================================
+  ================================ ==========================================
+  ``DPLL_A_PIN_ID``                configured pin id
+  ``DPLL_A_PIN_PHASE_ADJUST_GRAN`` attr granularity of phase adjustment value
+  ``DPLL_A_PIN_PHASE_ADJUST_MIN``  attr minimum value of phase adjustment
+  ``DPLL_A_PIN_PHASE_ADJUST_MAX``  attr maximum value of phase adjustment
+  ``DPLL_A_PIN_PHASE_ADJUST``      attr configured value of phase
+                                   adjustment on parent dpll device
+  ``DPLL_A_PIN_PARENT_DEVICE``     nested attribute for requesting
+                                   configuration on given parent dpll
+                                   device
+    ``DPLL_A_PIN_PARENT_ID``       parent dpll device id
+    ``DPLL_A_PIN_PHASE_OFFSET``    attr measured phase difference
+                                   between a pin and parent dpll device
+  ================================ ==========================================
 
 All phase related values are provided in pico seconds, which represents
 time difference between signals phase. The negative value means that
···
                                        frequencies
       ``DPLL_A_PIN_ANY_FREQUENCY_MIN`` attr minimum value of frequency
       ``DPLL_A_PIN_ANY_FREQUENCY_MAX`` attr maximum value of frequency
+    ``DPLL_A_PIN_PHASE_ADJUST_GRAN``   attr granularity of phase
+                                       adjustment value
     ``DPLL_A_PIN_PHASE_ADJUST_MIN``    attr minimum value of phase
                                        adjustment
     ``DPLL_A_PIN_PHASE_ADJUST_MAX``    attr maximum value of phase

Documentation/netlink/specs/dpll.yaml

···
         doc: |
           Capable pin provides list of pins that can be bound to create a
           reference-sync pin pair.
+      -
+        name: phase-adjust-gran
+        type: u32
+        doc: |
+          Granularity of phase adjustment, in picoseconds. The value of
+          phase adjustment must be a multiple of this granularity.
 
   -
     name: pin-parent-device
···
             - capabilities
             - parent-device
             - parent-pin
+            - phase-adjust-gran
             - phase-adjust-min
             - phase-adjust-max
             - phase-adjust

drivers/dpll/dpll_netlink.c

···
 	ret = dpll_msg_add_pin_freq(msg, pin, ref, extack);
 	if (ret)
 		return ret;
+	if (prop->phase_gran &&
+	    nla_put_u32(msg, DPLL_A_PIN_PHASE_ADJUST_GRAN,
+			prop->phase_gran))
+		return -EMSGSIZE;
 	if (nla_put_s32(msg, DPLL_A_PIN_PHASE_ADJUST_MIN,
 			prop->phase_range.min))
 		return -EMSGSIZE;
···
 	if (phase_adj > pin->prop.phase_range.max ||
 	    phase_adj < pin->prop.phase_range.min) {
 		NL_SET_ERR_MSG_ATTR(extack, phase_adj_attr,
-				    "phase adjust value not supported");
+				    "phase adjust value of out range");
+		return -EINVAL;
+	}
+	if (pin->prop.phase_gran && phase_adj % (s32)pin->prop.phase_gran) {
+		NL_SET_ERR_MSG_ATTR_FMT(extack, phase_adj_attr,
+					"phase adjust value not multiple of %u",
+					pin->prop.phase_gran);
 		return -EINVAL;
 	}
 

include/linux/dpll.h

···
 	u32 freq_supported_num;
 	struct dpll_pin_frequency *freq_supported;
 	struct dpll_pin_phase_adjust_range phase_range;
+	u32 phase_gran;
 };
 
 #if IS_ENABLED(CONFIG_DPLL)

include/uapi/linux/dpll.h

···
 	DPLL_A_PIN_ESYNC_FREQUENCY_SUPPORTED,
 	DPLL_A_PIN_ESYNC_PULSE,
 	DPLL_A_PIN_REFERENCE_SYNC,
+	DPLL_A_PIN_PHASE_ADJUST_GRAN,
 
 	__DPLL_A_PIN_MAX,
 	DPLL_A_PIN_MAX = (__DPLL_A_PIN_MAX - 1)