RE: [PATCH net-next v5 4/9] dpll: Support dynamic pin index allocation
From: "Kubalewski, Arkadiusz" <arkadiusz.kubalewski@intel.com>
Date: 2026-02-05 09:01:38
Also in:
intel-wired-lan, linux-rdma, lkml
From: Ivan Vecera <ivecera@redhat.com> Sent: Tuesday, February 3, 2026 6:40 PM 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. 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(). Reviewed-by: Aleksandr Loktionov <redacted>
LGTM, Reviewed-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@intel.com>
quoted hunk ↗ jump to hunk
Signed-off-by: Ivan Vecera <ivecera@redhat.com> --- v2: * fixed integer overflow in dpll_pin_idx_free() --- 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 b05fe2ba46d91..59081cf2c73ae 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;@@ -464,6 +466,36 @@ 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 -= (u32)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);@@ -521,9 +553,18 @@ dpll_pin_alloc(u64 clock_id, u32 pin_idx, structmodule *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;@@ -551,6 +592,8 @@ dpll_pin_alloc(u64 clock_id, u32 pin_idx, structmodule *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); }@@ -654,6 +697,7 @@ 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 8ed90dfc65f05..8fff048131f1d 100644 --- a/include/linux/dpll.h +++ b/include/linux/dpll.h@@ -240,6 +240,8 @@ 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); -- 2.52.0