[PATCH net-next v3 07/14] dpll: dpllsim: Add support to get/set priority on input pins

[Petr Oros <poros@redhat.com>]

Add support for getting and setting the priority of input pins.
Implement the prio_get and prio_set callbacks and advertise the
priority-can-change capability for input pins, which includes the MUX
type pins since those are always inputs.

The initial priority of a pin is configured through a new prio
attribute of the pin directory, which takes a value between 0 and 255
and defaults to 128, so that a test can lay out the reference order
before the device goes live. Like the other pin attributes it is
writable only while the device is not live. Priority changes made over
netlink are stored and reported back, they will drive the automatic
reference selection once the simulation loop exists. The setter
rejects a value above 255 with EINVAL and an extack message. A priority
is meaningful for input pins only, so live fails with EINVAL when an
output pin was given a priority other than the default, next to the
frequency validation.

Reviewed-by: Ivan Vecera <ivecera@redhat.com>
Acked-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Petr Oros <poros@redhat.com>
---
 Documentation/driver-api/dpllsim.rst |  5 ++++
 drivers/dpll/dpllsim/core.c          | 31 +++++++++++++++++++
 drivers/dpll/dpllsim/dpll.c          | 45 ++++++++++++++++++++++++++--
 drivers/dpll/dpllsim/dpllsim.h       | 10 ++++++-
 4 files changed, 88 insertions(+), 3 deletions(-)

diff --git a/Documentation/driver-api/dpllsim.rst b/Documentation/driver-api/dpllsim.rst
index e7c5ee93392c21..5109d67325f140 100644
--- a/Documentation/driver-api/dpllsim.rst
+++ b/Documentation/driver-api/dpllsim.rst
@@ -36,6 +36,9 @@ Pin directory ``/sys/kernel/config/dpllsim/<dev>/pins/<pin>/``:
                (default 0, which is rejected)
 ``direction``  ``input`` or ``output`` (default ``input``), a ``mux`` pin
                must be an input
+``prio``       Priority 0-255 used for automatic reference selection,
+               input pins only, output pins must keep the default
+               (default 128)
 =============  ===============================================================
 
 The pin directory name becomes the board label of the pin. Pins are
@@ -53,8 +56,10 @@ output, then make it live::
     mkdir pins/gnss0
     echo gnss > pins/gnss0/type
     echo 1 > pins/gnss0/frequency
+    echo 0 > pins/gnss0/prio
     mkdir pins/ext0
     echo 10000000 > pins/ext0/frequency
+    echo 1 > pins/ext0/prio
     mkdir pins/out0
     echo 10000000 > pins/out0/frequency
     echo output > pins/out0/direction
diff --git a/drivers/dpll/dpllsim/core.c b/drivers/dpll/dpllsim/core.c
index 97b3cf48772e7f..ee728a7f0c21bc 100644
--- a/drivers/dpll/dpllsim/core.c
+++ b/drivers/dpll/dpllsim/core.c
@@ -132,10 +132,40 @@ static ssize_t dpllsim_pin_frequency_store(struct config_item *item,
 }
 CONFIGFS_ATTR(dpllsim_pin_, frequency);
 
+static ssize_t dpllsim_pin_prio_show(struct config_item *item, char *page)
+{
+	struct dpllsim_pin *pin = to_dpllsim_pin(item);
+
+	guard(mutex)(&pin->dev->lock);
+	return sysfs_emit(page, "%u\n", pin->prio);
+}
+
+static ssize_t dpllsim_pin_prio_store(struct config_item *item,
+				      const char *page, size_t count)
+{
+	struct dpllsim_pin *pin = to_dpllsim_pin(item);
+	u32 val;
+	int err;
+
+	err = kstrtou32(page, 10, &val);
+	if (err)
+		return err;
+	if (val > DPLLSIM_PIN_PRIO_MAX)
+		return -EINVAL;
+
+	guard(mutex)(&pin->dev->lock);
+	if (dpllsim_dev_frozen(pin->dev))
+		return -EBUSY;
+	pin->prio = val;
+	return count;
+}
+CONFIGFS_ATTR(dpllsim_pin_, prio);
+
 static struct configfs_attribute *dpllsim_pin_attrs[] = {
 	&dpllsim_pin_attr_type,
 	&dpllsim_pin_attr_direction,
 	&dpllsim_pin_attr_frequency,
+	&dpllsim_pin_attr_prio,
 	NULL,
 };
 
@@ -178,6 +208,7 @@ static struct config_item *dpllsim_pins_make_item(struct config_group *group,
 	pin->dev = sim;
 	pin->type = DPLL_PIN_TYPE_EXT;
 	pin->direction = DPLL_PIN_DIRECTION_INPUT;
+	pin->prio = DPLLSIM_DEFAULT_PIN_PRIO;
 	list_add_tail(&pin->list, &sim->pin_list);
 
 	return &pin->item;
diff --git a/drivers/dpll/dpllsim/dpll.c b/drivers/dpll/dpllsim/dpll.c
index 794020d0c112e8..5e360596097616 100644
--- a/drivers/dpll/dpllsim/dpll.c
+++ b/drivers/dpll/dpllsim/dpll.c
@@ -139,11 +139,43 @@ static int dpllsim_pin_state_set(const struct dpll_pin *pin, void *pin_priv,
 	return 0;
 }
 
+static int dpllsim_pin_prio_get(const struct dpll_pin *pin, void *pin_priv,
+				const struct dpll_device *dpll,
+				void *dpll_priv, u32 *prio,
+				struct netlink_ext_ack *extack)
+{
+	struct dpllsim_pin *sim_pin = pin_priv;
+
+	guard(mutex)(&sim_pin->dev->lock);
+	*prio = sim_pin->prio;
+	return 0;
+}
+
+static int dpllsim_pin_prio_set(const struct dpll_pin *pin, void *pin_priv,
+				const struct dpll_device *dpll,
+				void *dpll_priv, u32 prio,
+				struct netlink_ext_ack *extack)
+{
+	struct dpllsim_pin *sim_pin = pin_priv;
+
+	if (prio > DPLLSIM_PIN_PRIO_MAX) {
+		NL_SET_ERR_MSG_FMT(extack, "Pin priority must be in range 0-%u",
+				   DPLLSIM_PIN_PRIO_MAX);
+		return -EINVAL;
+	}
+
+	guard(mutex)(&sim_pin->dev->lock);
+	sim_pin->prio = prio;
+	return 0;
+}
+
 static const struct dpll_pin_ops dpllsim_input_pin_ops = {
 	.frequency_get = dpllsim_pin_frequency_get,
 	.direction_get = dpllsim_pin_direction_get,
 	.state_on_dpll_get = dpllsim_pin_state_get,
 	.state_on_dpll_set = dpllsim_pin_state_set,
+	.prio_get = dpllsim_pin_prio_get,
+	.prio_set = dpllsim_pin_prio_set,
 };
 
 static const struct dpll_pin_ops dpllsim_output_pin_ops = {
@@ -188,7 +220,8 @@ static void dpllsim_pin_props(struct dpllsim_pin *pin,
 
 	/* Capabilities follow the ops the pin is served by */
 	if (dpllsim_pin_select_ops(pin) == &dpllsim_input_pin_ops)
-		prop->capabilities = DPLL_PIN_CAPABILITIES_STATE_CAN_CHANGE;
+		prop->capabilities = DPLL_PIN_CAPABILITIES_STATE_CAN_CHANGE |
+				     DPLL_PIN_CAPABILITIES_PRIORITY_CAN_CHANGE;
 	else
 		prop->capabilities = 0;
 }
@@ -214,6 +247,13 @@ static bool dpllsim_pin_direction_valid(const struct dpllsim_pin *pin)
 	       pin->direction == DPLL_PIN_DIRECTION_INPUT;
 }
 
+/* Priority is meaningful for input pins only */
+static bool dpllsim_pin_prio_valid(const struct dpllsim_pin *pin)
+{
+	return pin->direction == DPLL_PIN_DIRECTION_INPUT ||
+	       pin->prio == DPLLSIM_DEFAULT_PIN_PRIO;
+}
+
 static void dpllsim_pin_reset(struct dpllsim_pin *pin)
 {
 	pin->ops = dpllsim_pin_select_ops(pin);
@@ -228,7 +268,8 @@ static int dpllsim_order_pins(struct dpllsim_dev *sim)
 
 	list_for_each_entry(pin, &sim->pin_list, list) {
 		if (!dpllsim_pin_frequency_valid(pin) ||
-		    !dpllsim_pin_direction_valid(pin))
+		    !dpllsim_pin_direction_valid(pin) ||
+		    !dpllsim_pin_prio_valid(pin))
 			return -EINVAL;
 		count++;
 	}
diff --git a/drivers/dpll/dpllsim/dpllsim.h b/drivers/dpll/dpllsim/dpllsim.h
index 73b846b66f79c7..f9fced337dc881 100644
--- a/drivers/dpll/dpllsim/dpllsim.h
+++ b/drivers/dpll/dpllsim/dpllsim.h
@@ -12,6 +12,9 @@
 #include <linux/list.h>
 #include <linux/mutex.h>
 
+#define DPLLSIM_DEFAULT_PIN_PRIO		128
+#define DPLLSIM_PIN_PRIO_MAX			255
+
 #define DPLLSIM_MAX_PINS			128
 
 struct dpllsim_dev;
@@ -21,10 +24,15 @@ struct dpllsim_pin {
 	struct list_head list;
 	struct dpllsim_dev *dev;
 
-	/* Configuration, writable only until dpllsim_dev_frozen() */
+	/*
+	 * Configuration, set through configfs only until
+	 * dpllsim_dev_frozen(). The netlink prio setter changes prio at
+	 * runtime under dev->lock.
+	 */
 	enum dpll_pin_type type;
 	enum dpll_pin_direction direction;
 	u64 frequency;
+	u32 prio;
 
 	/* Resolved at live=1 */
 	int idx;
-- 
2.56.0