[PATCH net-next v2 0/3] dpll: support mode switching

[PATCH net-next v2 0/3] dpll: support mode switching

[Ivan Vecera]

This series adds support for switching the working mode (automatic vs
manual) of a DPLL device via netlink.

Currently, the DPLL subsystem allows userspace to retrieve the current
working mode but lacks the mechanism to configure it. Userspace is also
unaware of which modes a specific device actually supports, as it
currently assumes only the active mode is supported.

The series addresses these limitations by:
1. Introducing .supported_modes_get() callback to allow drivers to report
   all modes capable of running on the device.
2. Introducing .mode_set() callback and updating the netlink policy
   to allow userspace to request a mode change.
3. Implementing these callbacks in the zl3073x driver, enabling dynamic
   switching between automatic and manual modes.

Changelog:
v2 - addressed issues reported by Vadim

Ivan Vecera (3):
  dpll: add dpll_device op to get supported modes
  dpll: add dpll_device op to set working mode
  dpll: zl3073x: Implement device mode setting support

 Documentation/netlink/specs/dpll.yaml |   1 +
 drivers/dpll/dpll_netlink.c           |  71 ++++++++++++++--
 drivers/dpll/dpll_nl.c                |   1 +
 drivers/dpll/zl3073x/dpll.c           | 112 ++++++++++++++++++++++++++
 include/linux/dpll.h                  |   5 ++
 5 files changed, 182 insertions(+), 8 deletions(-)

-- 
2.52.0

[PATCH net-next v2 1/3] dpll: add dpll_device op to get supported modes

[Ivan Vecera]

Currently, the DPLL subsystem assumes that the only supported mode is
the one currently active on the device. When dpll_msg_add_mode_supported()
is called, it relies on ops->mode_get() and reports that single mode
to userspace. This prevents users from discovering other modes the device
might be capable of.

Add a new callback .supported_modes_get() to struct dpll_device_ops. This
allows drivers to populate a bitmap indicating all modes supported by
the hardware.

Update dpll_msg_add_mode_supported() to utilize this new callback:

* if ops->supported_modes_get is defined, use it to retrieve the full
  bitmap of supported modes.
* if not defined, fall back to the existing behavior: retrieve
  the current mode via ops->mode_get and set the corresponding bit
  in the bitmap.

Finally, iterate over the bitmap and add a DPLL_A_MODE_SUPPORTED netlink
attribute for every set bit, accurately reporting the device's capabilities
to userspace.

Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
---
 drivers/dpll/dpll_netlink.c | 27 +++++++++++++++++++--------
 include/linux/dpll.h        |  3 +++
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c
index 64944f601ee5a..d6a0e272d7038 100644
--- a/drivers/dpll/dpll_netlink.c
+++ b/drivers/dpll/dpll_netlink.c
@@ -128,18 +128,29 @@ dpll_msg_add_mode_supported(struct sk_buff *msg, struct dpll_device *dpll,
 			    struct netlink_ext_ack *extack)
 {
 	const struct dpll_device_ops *ops = dpll_device_ops(dpll);
+	DECLARE_BITMAP(modes, DPLL_MODE_MAX + 1) = { 0 };
 	enum dpll_mode mode;
 	int ret;
 
-	/* No mode change is supported now, so the only supported mode is the
-	 * one obtained by mode_get().
-	 */
+	if (ops->supported_modes_get) {
+		ret = ops->supported_modes_get(dpll, dpll_priv(dpll), modes,
+					       extack);
+		if (ret)
+			return ret;
+	} else {
+		/* If the supported modes are not reported by the driver, the
+		 * only supported mode is the one obtained by mode_get().
+		 */
+		ret = ops->mode_get(dpll, dpll_priv(dpll), &mode, extack);
+		if (ret)
+			return ret;
 
-	ret = ops->mode_get(dpll, dpll_priv(dpll), &mode, extack);
-	if (ret)
-		return ret;
-	if (nla_put_u32(msg, DPLL_A_MODE_SUPPORTED, mode))
-		return -EMSGSIZE;
+		__set_bit(mode, modes);
+	}
+
+	for_each_set_bit(mode, modes, DPLL_MODE_MAX + 1)
+		if (nla_put_u32(msg, DPLL_A_MODE_SUPPORTED, mode))
+			return -EMSGSIZE;
 
 	return 0;
 }
diff --git a/include/linux/dpll.h b/include/linux/dpll.h
index 562f520b23c27..912a2ca3e0ee7 100644
--- a/include/linux/dpll.h
+++ b/include/linux/dpll.h
@@ -20,6 +20,9 @@ struct dpll_pin_esync;
 struct dpll_device_ops {
 	int (*mode_get)(const struct dpll_device *dpll, void *dpll_priv,
 			enum dpll_mode *mode, struct netlink_ext_ack *extack);
+	int (*supported_modes_get)(const struct dpll_device *dpll,
+				   void *dpll_priv, unsigned long *modes,
+				   struct netlink_ext_ack *extack);
 	int (*lock_status_get)(const struct dpll_device *dpll, void *dpll_priv,
 			       enum dpll_lock_status *status,
 			       enum dpll_lock_status_error *status_error,
-- 
2.52.0

[PATCH net-next v2 2/3] dpll: add dpll_device op to set working mode

[Ivan Vecera]

Currently, userspace can retrieve the DPLL working mode but cannot
configure it. This prevents changing the device operation, such as
switching from manual to automatic mode and vice versa.

Add a new callback .mode_set() to struct dpll_device_ops. Extend
the netlink policy and device-set command handling to process
the DPLL_A_MODE attribute.  Update the netlink YAML specification
to include the mode attribute in the device-set operation.

Signed-off-by: Ivan Vecera <ivecera@redhat.com>
---
v2:
* fixed bitmap size in dpll_mode_set()
---
 Documentation/netlink/specs/dpll.yaml |  1 +
 drivers/dpll/dpll_netlink.c           | 44 +++++++++++++++++++++++++++
 drivers/dpll/dpll_nl.c                |  1 +
 include/linux/dpll.h                  |  2 ++
 4 files changed, 48 insertions(+)

diff --git a/Documentation/netlink/specs/dpll.yaml b/Documentation/netlink/specs/dpll.yaml
index 78d0724d7e12c..b55afa77eac4b 100644
--- a/Documentation/netlink/specs/dpll.yaml
+++ b/Documentation/netlink/specs/dpll.yaml
@@ -550,6 +550,7 @@ operations:
         request:
           attributes:
             - id
+            - mode
             - phase-offset-monitor
             - phase-offset-avg-factor
     -
diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c
index d6a0e272d7038..7a72d5d0d7093 100644
--- a/drivers/dpll/dpll_netlink.c
+++ b/drivers/dpll/dpll_netlink.c
@@ -853,6 +853,45 @@ int dpll_pin_change_ntf(struct dpll_pin *pin)
 }
 EXPORT_SYMBOL_GPL(dpll_pin_change_ntf);
 
+static int
+dpll_mode_set(struct dpll_device *dpll, struct nlattr *a,
+	      struct netlink_ext_ack *extack)
+{
+	const struct dpll_device_ops *ops = dpll_device_ops(dpll);
+	enum dpll_mode mode = nla_get_u32(a), old_mode;
+	DECLARE_BITMAP(modes, DPLL_MODE_MAX + 1) = { 0 };
+	int ret;
+
+	if (!(ops->mode_set && ops->supported_modes_get)) {
+		NL_SET_ERR_MSG_ATTR(extack, a,
+				    "dpll device does not support mode switch");
+		return -EOPNOTSUPP;
+	}
+
+	ret = ops->mode_get(dpll, dpll_priv(dpll), &old_mode, extack);
+	if (ret) {
+		NL_SET_ERR_MSG(extack, "unable to get current mode");
+		return ret;
+	}
+
+	if (mode == old_mode)
+		return 0;
+
+	ret = ops->supported_modes_get(dpll, dpll_priv(dpll), modes, extack);
+	if (ret) {
+		NL_SET_ERR_MSG(extack, "unable to get supported modes");
+		return ret;
+	}
+
+	if (!test_bit(mode, modes)) {
+		NL_SET_ERR_MSG(extack,
+			       "dpll device does not support requested mode");
+		return -EINVAL;
+	}
+
+	return ops->mode_set(dpll, dpll_priv(dpll), mode, extack);
+}
+
 static int
 dpll_phase_offset_monitor_set(struct dpll_device *dpll, struct nlattr *a,
 			      struct netlink_ext_ack *extack)
@@ -1808,6 +1847,11 @@ dpll_set_from_nlattr(struct dpll_device *dpll, struct genl_info *info)
 	nla_for_each_attr(a, genlmsg_data(info->genlhdr),
 			  genlmsg_len(info->genlhdr), rem) {
 		switch (nla_type(a)) {
+		case DPLL_A_MODE:
+			ret = dpll_mode_set(dpll, a, info->extack);
+			if (ret)
+				return ret;
+			break;
 		case DPLL_A_PHASE_OFFSET_MONITOR:
 			ret = dpll_phase_offset_monitor_set(dpll, a,
 							    info->extack);
diff --git a/drivers/dpll/dpll_nl.c b/drivers/dpll/dpll_nl.c
index 36d11ff195df4..a2b22d4921142 100644
--- a/drivers/dpll/dpll_nl.c
+++ b/drivers/dpll/dpll_nl.c
@@ -45,6 +45,7 @@ static const struct nla_policy dpll_device_get_nl_policy[DPLL_A_ID + 1] = {
 /* DPLL_CMD_DEVICE_SET - do */
 static const struct nla_policy dpll_device_set_nl_policy[DPLL_A_PHASE_OFFSET_AVG_FACTOR + 1] = {
 	[DPLL_A_ID] = { .type = NLA_U32, },
+	[DPLL_A_MODE] = NLA_POLICY_RANGE(NLA_U32, 1, 2),
 	[DPLL_A_PHASE_OFFSET_MONITOR] = NLA_POLICY_MAX(NLA_U32, 1),
 	[DPLL_A_PHASE_OFFSET_AVG_FACTOR] = { .type = NLA_U32, },
 };
diff --git a/include/linux/dpll.h b/include/linux/dpll.h
index 912a2ca3e0ee7..c6d0248fa5273 100644
--- a/include/linux/dpll.h
+++ b/include/linux/dpll.h
@@ -20,6 +20,8 @@ struct dpll_pin_esync;
 struct dpll_device_ops {
 	int (*mode_get)(const struct dpll_device *dpll, void *dpll_priv,
 			enum dpll_mode *mode, struct netlink_ext_ack *extack);
+	int (*mode_set)(const struct dpll_device *dpll, void *dpll_priv,
+			enum dpll_mode mode, struct netlink_ext_ack *extack);
 	int (*supported_modes_get)(const struct dpll_device *dpll,
 				   void *dpll_priv, unsigned long *modes,
 				   struct netlink_ext_ack *extack);
-- 
2.52.0

Re: [PATCH net-next v2 2/3] dpll: add dpll_device op to set working mode

[Vadim Fedorenko]

On 13/01/2026 12:16, Ivan Vecera wrote:
> Currently, userspace can retrieve the DPLL working mode but cannot
> configure it. This prevents changing the device operation, such as
> switching from manual to automatic mode and vice versa.
> 
> Add a new callback .mode_set() to struct dpll_device_ops. Extend
> the netlink policy and device-set command handling to process
> the DPLL_A_MODE attribute.  Update the netlink YAML specification
> to include the mode attribute in the device-set operation.
> 
> Signed-off-by: Ivan Vecera <ivecera@redhat.com>
> ---
> v2:
> * fixed bitmap size in dpll_mode_set()

[...]

> +static int
> +dpll_mode_set(struct dpll_device *dpll, struct nlattr *a,
> +	      struct netlink_ext_ack *extack)
> +{
> +	const struct dpll_device_ops *ops = dpll_device_ops(dpll);
> +	enum dpll_mode mode = nla_get_u32(a), old_mode;
> +	DECLARE_BITMAP(modes, DPLL_MODE_MAX + 1) = { 0 };

this one breaks reverse xmas tree order.

with this fixed:
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>

Re: [PATCH net-next v2 2/3] dpll: add dpll_device op to set working mode

[Ivan Vecera]

On 1/13/26 6:47 PM, Vadim Fedorenko wrote:
> On 13/01/2026 12:16, Ivan Vecera wrote:
>> Currently, userspace can retrieve the DPLL working mode but cannot
>> configure it. This prevents changing the device operation, such as
>> switching from manual to automatic mode and vice versa.
>>
>> Add a new callback .mode_set() to struct dpll_device_ops. Extend
>> the netlink policy and device-set command handling to process
>> the DPLL_A_MODE attribute.  Update the netlink YAML specification
>> to include the mode attribute in the device-set operation.
>>
>> Signed-off-by: Ivan Vecera <ivecera@redhat.com>
>> ---
>> v2:
>> * fixed bitmap size in dpll_mode_set()
> 
> [...]
> 
>> +static int
>> +dpll_mode_set(struct dpll_device *dpll, struct nlattr *a,
>> +          struct netlink_ext_ack *extack)
>> +{
>> +    const struct dpll_device_ops *ops = dpll_device_ops(dpll);
>> +    enum dpll_mode mode = nla_get_u32(a), old_mode;
>> +    DECLARE_BITMAP(modes, DPLL_MODE_MAX + 1) = { 0 };
> 
> this one breaks reverse xmas tree order.

oops, my bad :-(

> with this fixed:
> Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>

will fix... thanks for pointing this out.

Ivan

[PATCH net-next v2 3/3] dpll: zl3073x: Implement device mode setting support

[Ivan Vecera]

Add support for .supported_modes_get() and .mode_set() callbacks
to enable switching between manual and automatic modes via netlink.

Implement .supported_modes_get() to report available modes based
on the current hardware configuration:

* manual mode is always supported
* automatic mode is supported unless the dpll channel is configured
  in NCO (Numerically Controlled Oscillator) mode

Implement .mode_set() to handle the specific logic required when
transitioning between modes:

1) Transition to manual:
* If a valid reference is currently active, switch the hardware
  to ref-lock mode (force lock to that reference).
* If no reference is valid and the DPLL is unlocked, switch to freerun.
* Otherwise, switch to Holdover.

2) Transition to automatic:
* If the currently selected reference pin was previously marked
  as non-selectable (likely during a previous manual forcing
  operation), restore its priority and selectability in the hardware.
* Switch the hardware to Automatic selection mode.

Signed-off-by: Ivan Vecera <ivecera@redhat.com>
---
v2:
* added extack error messages in error paths
---
 drivers/dpll/zl3073x/dpll.c | 112 ++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)

diff --git a/drivers/dpll/zl3073x/dpll.c b/drivers/dpll/zl3073x/dpll.c
index 9879d85d29af0..7d8ed948b9706 100644
--- a/drivers/dpll/zl3073x/dpll.c
+++ b/drivers/dpll/zl3073x/dpll.c
@@ -100,6 +100,20 @@ zl3073x_dpll_pin_direction_get(const struct dpll_pin *dpll_pin, void *pin_priv,
 	return 0;
 }
 
+static struct zl3073x_dpll_pin *
+zl3073x_dpll_pin_get_by_ref(struct zl3073x_dpll *zldpll, u8 ref_id)
+{
+	struct zl3073x_dpll_pin *pin;
+
+	list_for_each_entry(pin, &zldpll->pins, list) {
+		if (zl3073x_dpll_is_input_pin(pin) &&
+		    zl3073x_input_pin_ref_get(pin->id) == ref_id)
+			return pin;
+	}
+
+	return NULL;
+}
+
 static int
 zl3073x_dpll_input_pin_esync_get(const struct dpll_pin *dpll_pin,
 				 void *pin_priv,
@@ -1137,6 +1151,26 @@ zl3073x_dpll_lock_status_get(const struct dpll_device *dpll, void *dpll_priv,
 	return 0;
 }
 
+static int
+zl3073x_dpll_supported_modes_get(const struct dpll_device *dpll,
+				 void *dpll_priv, unsigned long *modes,
+				 struct netlink_ext_ack *extack)
+{
+	struct zl3073x_dpll *zldpll = dpll_priv;
+
+	/* We support switching between automatic and manual mode, except in
+	 * a case where the DPLL channel is configured to run in NCO mode.
+	 * In this case, report only the manual mode to which the NCO is mapped
+	 * as the only supported one.
+	 */
+	if (zldpll->refsel_mode != ZL_DPLL_MODE_REFSEL_MODE_NCO)
+		__set_bit(DPLL_MODE_AUTOMATIC, modes);
+
+	__set_bit(DPLL_MODE_MANUAL, modes);
+
+	return 0;
+}
+
 static int
 zl3073x_dpll_mode_get(const struct dpll_device *dpll, void *dpll_priv,
 		      enum dpll_mode *mode, struct netlink_ext_ack *extack)
@@ -1217,6 +1251,82 @@ zl3073x_dpll_phase_offset_avg_factor_set(const struct dpll_device *dpll,
 	return 0;
 }
 
+static int
+zl3073x_dpll_mode_set(const struct dpll_device *dpll, void *dpll_priv,
+		      enum dpll_mode mode, struct netlink_ext_ack *extack)
+{
+	struct zl3073x_dpll *zldpll = dpll_priv;
+	u8 hw_mode, mode_refsel, ref;
+	int rc;
+
+	rc = zl3073x_dpll_selected_ref_get(zldpll, &ref);
+	if (rc) {
+		NL_SET_ERR_MSG_MOD(extack, "failed to get selected reference");
+		return rc;
+	}
+
+	if (mode == DPLL_MODE_MANUAL) {
+		/* We are switching from automatic to manual mode:
+		 * - if we have a valid reference selected during auto mode then
+		 *   we will switch to forced reference lock mode and use this
+		 *   reference for selection
+		 * - if NO valid reference is selected, we will switch to forced
+		 *   holdover mode or freerun mode, depending on the current
+		 *   lock status
+		 */
+		if (ZL3073X_DPLL_REF_IS_VALID(ref))
+			hw_mode = ZL_DPLL_MODE_REFSEL_MODE_REFLOCK;
+		else if (zldpll->lock_status == DPLL_LOCK_STATUS_UNLOCKED)
+			hw_mode = ZL_DPLL_MODE_REFSEL_MODE_FREERUN;
+		else
+			hw_mode = ZL_DPLL_MODE_REFSEL_MODE_HOLDOVER;
+	} else {
+		/* We are switching from manual to automatic mode:
+		 * - if there is a valid reference selected then ensure that
+		 *   it is selectable after switch to automatic mode
+		 * - switch to automatic mode
+		 */
+		struct zl3073x_dpll_pin *pin;
+
+		pin = zl3073x_dpll_pin_get_by_ref(zldpll, ref);
+		if (pin && !pin->selectable) {
+			/* Restore pin priority in HW */
+			rc = zl3073x_dpll_ref_prio_set(pin, pin->prio);
+			if (rc) {
+				NL_SET_ERR_MSG_MOD(extack,
+						   "failed to restore pin priority");
+				return rc;
+			}
+
+			pin->selectable = true;
+		}
+
+		hw_mode = ZL_DPLL_MODE_REFSEL_MODE_AUTO;
+	}
+
+	/* Build mode_refsel value */
+	mode_refsel = FIELD_PREP(ZL_DPLL_MODE_REFSEL_MODE, hw_mode);
+
+	if (ZL3073X_DPLL_REF_IS_VALID(ref))
+		mode_refsel |= FIELD_PREP(ZL_DPLL_MODE_REFSEL_REF, ref);
+
+	/* Update dpll_mode_refsel register */
+	rc = zl3073x_write_u8(zldpll->dev, ZL_REG_DPLL_MODE_REFSEL(zldpll->id),
+			      mode_refsel);
+	if (rc) {
+		NL_SET_ERR_MSG_MOD(extack,
+				   "failed to set reference selection mode");
+		return rc;
+	}
+
+	zldpll->refsel_mode = hw_mode;
+
+	if (ZL3073X_DPLL_REF_IS_VALID(ref))
+		zldpll->forced_ref = ref;
+
+	return 0;
+}
+
 static int
 zl3073x_dpll_phase_offset_monitor_get(const struct dpll_device *dpll,
 				      void *dpll_priv,
@@ -1276,10 +1386,12 @@ static const struct dpll_pin_ops zl3073x_dpll_output_pin_ops = {
 static const struct dpll_device_ops zl3073x_dpll_device_ops = {
 	.lock_status_get = zl3073x_dpll_lock_status_get,
 	.mode_get = zl3073x_dpll_mode_get,
+	.mode_set = zl3073x_dpll_mode_set,
 	.phase_offset_avg_factor_get = zl3073x_dpll_phase_offset_avg_factor_get,
 	.phase_offset_avg_factor_set = zl3073x_dpll_phase_offset_avg_factor_set,
 	.phase_offset_monitor_get = zl3073x_dpll_phase_offset_monitor_get,
 	.phase_offset_monitor_set = zl3073x_dpll_phase_offset_monitor_set,
+	.supported_modes_get = zl3073x_dpll_supported_modes_get,
 };
 
 /**
-- 
2.52.0