path: root/drivers/dpll/dpll_core.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  dpll_core.c - DPLL subsystem kernel-space interface implementation.
 *
 *  Copyright (c) 2023 Meta Platforms, Inc. and affiliates
 *  Copyright (c) 2023 Intel Corporation.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/device.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/string.h>

#include "dpll_core.h"
#include "dpll_netlink.h"

/* Mutex lock to protect DPLL subsystem devices and pins */
DEFINE_MUTEX(dpll_lock);

DEFINE_XARRAY_FLAGS(dpll_device_xa, XA_FLAGS_ALLOC);
DEFINE_XARRAY_FLAGS(dpll_pin_xa, XA_FLAGS_ALLOC);

static u32 dpll_device_xa_id;
static u32 dpll_pin_xa_id;

#define ASSERT_DPLL_REGISTERED(d)	\
	WARN_ON_ONCE(!xa_get_mark(&dpll_device_xa, (d)->id, DPLL_REGISTERED))
#define ASSERT_DPLL_NOT_REGISTERED(d)	\
	WARN_ON_ONCE(xa_get_mark(&dpll_device_xa, (d)->id, DPLL_REGISTERED))
#define ASSERT_DPLL_PIN_REGISTERED(p) \
	WARN_ON_ONCE(!xa_get_mark(&dpll_pin_xa, (p)->id, DPLL_REGISTERED))

struct dpll_device_registration {
	struct list_head list;
	const struct dpll_device_ops *ops;
	void *priv;
};

struct dpll_pin_registration {
	struct list_head list;
	const struct dpll_pin_ops *ops;
	void *priv;
	void *cookie;
};

struct dpll_device *dpll_device_get_by_id(int id)
{
	if (xa_get_mark(&dpll_device_xa, id, DPLL_REGISTERED))
		return xa_load(&dpll_device_xa, id);

	return NULL;
}

static struct dpll_pin_registration *
dpll_pin_registration_find(struct dpll_pin_ref *ref,
			   const struct dpll_pin_ops *ops, void *priv,
			   void *cookie)
{
	struct dpll_pin_registration *reg;

	list_for_each_entry(reg, &ref->registration_list, list) {
		if (reg->ops == ops && reg->priv == priv &&
		    reg->cookie == cookie)
			return reg;
	}
	return NULL;
}

static int
dpll_xa_ref_pin_add(struct xarray *xa_pins, struct dpll_pin *pin,
		    const struct dpll_pin_ops *ops, void *priv,
		    void *cookie)
{
	struct dpll_pin_registration *reg;
	struct dpll_pin_ref *ref;
	bool ref_exists = false;
	unsigned long i;
	int ret;

	xa_for_each(xa_pins, i, ref) {
		if (ref->pin != pin)
			continue;
		reg = dpll_pin_registration_find(ref, ops, priv, cookie);
		if (reg)
			return -EEXIST;
		ref_exists = true;
		break;
	}

	if (!ref_exists) {
		ref = kzalloc(sizeof(*ref), GFP_KERNEL);
		if (!ref)
			return -ENOMEM;
		ref->pin = pin;
		INIT_LIST_HEAD(&ref->registration_list);
		ret = xa_insert(xa_pins, pin->pin_idx, ref, GFP_KERNEL);
		if (ret) {
			kfree(ref);
			return ret;
		}
		refcount_set(&ref->refcount, 1);
	}

	reg = kzalloc(sizeof(*reg), GFP_KERNEL);
	if (!reg) {
		if (!ref_exists) {
			xa_erase(xa_pins, pin->pin_idx);
			kfree(ref);
		}
		return -ENOMEM;
	}
	reg->ops = ops;
	reg->priv = priv;
	reg->cookie = cookie;
	if (ref_exists)
		refcount_inc(&ref->refcount);
	list_add_tail(&reg->list, &ref->registration_list);

	return 0;
}

static int dpll_xa_ref_pin_del(struct xarray *xa_pins, struct dpll_pin *pin,
			       const struct dpll_pin_ops *ops, void *priv,
			       void *cookie)
{
	struct dpll_pin_registration *reg;
	struct dpll_pin_ref *ref;
	unsigned long i;

	xa_for_each(xa_pins, i, ref) {
		if (ref->pin != pin)
			continue;
		reg = dpll_pin_registration_find(ref, ops, priv, cookie);
		if (WARN_ON(!reg))
			return -EINVAL;
		list_del(&reg->list);
		kfree(reg);
		if (refcount_dec_and_test(&ref->refcount)) {
			xa_erase(xa_pins, i);
			WARN_ON(!list_empty(&ref->registration_list));
			kfree(ref);
		}
		return 0;
	}

	return -EINVAL;
}

static int
dpll_xa_ref_dpll_add(struct xarray *xa_dplls, struct dpll_device *dpll,
		     const struct dpll_pin_ops *ops, void *priv, void *cookie)
{
	struct dpll_pin_registration *reg;
	struct dpll_pin_ref *ref;
	bool ref_exists = false;
	unsigned</