On 12/11/25 20:47, Ivan Vecera wrote:
Allow drivers to register DPLL pins without manually specifying a pin
index.
Currently, drivers must provide a unique pin index when calling
dpll_pin_get(). This works well for hardware-mapped pins but creates
friction for drivers handling virtual pins or those without a strict
hardware indexing scheme.
wouldn't it be better to just switch everything to allocated IDs?
Introduce DPLL_PIN_IDX_UNSPEC (U32_MAX). When a driver passes this
value as the pin index:
1. The core allocates a unique index using an IDA
2. The allocated index is mapped to a range starting above `INT_MAX`
This separation ensures that dynamically allocated indices never collide
with standard driver-provided hardware indices, which are assumed to be
within the `0` to `INT_MAX` range. The index is automatically freed when
the pin is released in dpll_pin_put().
Signed-off-by: Ivan Vecera <[email protected]>
---
drivers/dpll/dpll_core.c | 48 ++++++++++++++++++++++++++++++++++++++--
include/linux/dpll.h | 2 ++
2 files changed, 48 insertions(+), 2 deletions(-)
diff --git a/drivers/dpll/dpll_core.c b/drivers/dpll/dpll_core.c
index fecc3d97acf5b..79f60e0de27ac 100644
--- a/drivers/dpll/dpll_core.c
+++ b/drivers/dpll/dpll_core.c
@@ -10,6 +10,7 @@
#include <linux/device.h>
#include <linux/err.h>
+#include <linux/idr.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <linux/string.h>
@@ -24,6 +25,7 @@ DEFINE_XARRAY_FLAGS(dpll_device_xa, XA_FLAGS_ALLOC);
DEFINE_XARRAY_FLAGS(dpll_pin_xa, XA_FLAGS_ALLOC);
static RAW_NOTIFIER_HEAD(dpll_notifier_chain);
+static DEFINE_IDA(dpll_pin_idx_ida);
static u32 dpll_device_xa_id;
static u32 dpll_pin_xa_id;
@@ -468,6 +470,36 @@ void dpll_device_unregister(struct dpll_device *dpll,
}
EXPORT_SYMBOL_GPL(dpll_device_unregister);
+static int dpll_pin_idx_alloc(u32 *pin_idx)
+{
+ int ret;
+
+ if (!pin_idx)
+ return -EINVAL;
+
+ /* Alloc unique number from IDA. Number belongs to <0, INT_MAX> range */
+ ret = ida_alloc(&dpll_pin_idx_ida, GFP_KERNEL);
+ if (ret < 0)
+ return ret;
+
+ /* Map the value to dynamic pin index range <INT_MAX+1, U32_MAX> */
+ *pin_idx = (u32)ret + INT_MAX + 1;
+
+ return 0;
+}
+
+static void dpll_pin_idx_free(u32 pin_idx)
+{
+ if (pin_idx <= INT_MAX)
+ return; /* Not a dynamic pin index */
+
+ /* Map the index value from dynamic pin index range to IDA range and
+ * free it.
+ */
+ pin_idx -= INT_MAX - 1;
+ ida_free(&dpll_pin_idx_ida, pin_idx);
+}
+
static void dpll_pin_prop_free(struct dpll_pin_properties *prop)
{
kfree(prop->package_label);
@@ -526,9 +558,18 @@ dpll_pin_alloc(u64 clock_id, u32 pin_idx, struct module
*module,
struct dpll_pin *pin;
int ret;
+ if (pin_idx == DPLL_PIN_IDX_UNSPEC) {
+ ret = dpll_pin_idx_alloc(&pin_idx);
+ if (ret)
+ return ERR_PTR(ret);
+ } else if (pin_idx > INT_MAX) {
+ return ERR_PTR(-EINVAL);
+ }
pin = kzalloc(sizeof(*pin), GFP_KERNEL);
- if (!pin)
- return ERR_PTR(-ENOMEM);
+ if (!pin) {
+ ret = -ENOMEM;
+ goto err_pin_alloc;
+ }
pin->pin_idx = pin_idx;
pin->clock_id = clock_id;
pin->module = module;
@@ -557,6 +598,8 @@ dpll_pin_alloc(u64 clock_id, u32 pin_idx, struct module
*module,
dpll_pin_prop_free(&pin->prop);
err_pin_prop:
kfree(pin);
+err_pin_alloc:
+ dpll_pin_idx_free(pin_idx);
return ERR_PTR(ret);
}
@@ -663,6 +706,7 @@ void dpll_pin_put(struct dpll_pin *pin)
xa_destroy(&pin->ref_sync_pins);
dpll_pin_prop_free(&pin->prop);
fwnode_handle_put(pin->fwnode);
+ dpll_pin_idx_free(pin->pin_idx);
kfree_rcu(pin, rcu);
}
mutex_unlock(&dpll_lock);
diff --git a/include/linux/dpll.h b/include/linux/dpll.h
index 441afb90d2a29..8aa1df38ce563 100644
--- a/include/linux/dpll.h
+++ b/include/linux/dpll.h
@@ -235,6 +235,8 @@ int dpll_device_register(struct dpll_device *dpll, enum
dpll_type type,
void dpll_device_unregister(struct dpll_device *dpll,
const struct dpll_device_ops *ops, void *priv);
+#define DPLL_PIN_IDX_UNSPEC U32_MAX
+
struct dpll_pin *
dpll_pin_get(u64 clock_id, u32 dev_driver_id, struct module *module,
const struct dpll_pin_properties *prop,
