// SPDX-License-Identifier: GPL-2.0-or-later
 /* Management for virtio crypto devices (refer to adf_dev_mgr.c)
  *
  * Copyright 2016 HUAWEI TECHNOLOGIES CO., LTD.
  */

#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/module.h>

#include <uapi/linux/virtio_crypto.h>
#include "virtio_crypto_common.h"

static LIST_HEAD(virtio_crypto_table);
static uint32_t num_devices;

/* The table_lock protects the above global list and num_devices */
static DEFINE_MUTEX(table_lock);

#define VIRTIO_CRYPTO_MAX_DEVICES 32


/*
 * virtcrypto_devmgr_add_dev() - Add vcrypto_dev to the acceleration
 * framework.
 * @vcrypto_dev:  Pointer to virtio crypto device.
 *
 * Function adds virtio crypto device to the global list.
 * To be used by virtio crypto device specific drivers.
 *
 * Return: 0 on success, error code othewise.
 */
int virtcrypto_devmgr_add_dev(struct virtio_crypto *vcrypto_dev)
{
        struct list_head *itr;

        mutex_lock(&table_lock);
        if (num_devices == VIRTIO_CRYPTO_MAX_DEVICES) {
                pr_info("virtio_crypto: only support up to %d devices\n",
                            VIRTIO_CRYPTO_MAX_DEVICES);
                mutex_unlock(&table_lock);
                return -EFAULT;
        }

        list_for_each(itr, &virtio_crypto_table) {
                struct virtio_crypto *ptr =
                                list_entry(itr, struct virtio_crypto, list);

                if (ptr == vcrypto_dev) {
                        mutex_unlock(&table_lock);
                        return -EEXIST;
                }
        }
        atomic_set(&vcrypto_dev->ref_count, 0);
        list_add_tail(&vcrypto_dev->list, &virtio_crypto_table);
        vcrypto_dev->dev_id = num_devices++;
        mutex_unlock(&table_lock);
        return 0;
}

struct list_head *virtcrypto_devmgr_get_head(void)
{
        return &virtio_crypto_table;
}

/*
 * virtcrypto_devmgr_rm_dev() - Remove vcrypto_dev from the acceleration
 * framework.
 * @vcrypto_dev:  Pointer to virtio crypto device.
 *
 * Function removes virtio crypto device from the acceleration framework.
 * To be used by virtio crypto device specific drivers.
 *
 * Return: void
 */
void virtcrypto_devmgr_rm_dev(struct virtio_crypto *vcrypto_dev)
{
        mutex_lock(&table_lock);
        list_del(&vcrypto_dev->list);
        num_devices--;
        mutex_unlock(&table_lock);
}

/*
 * virtcrypto_devmgr_get_first()
 *
 * Function returns the first virtio crypto device from the acceleration
 * framework.
 *
 * To be used by virtio crypto device specific drivers.
 *
 * Return: pointer to vcrypto_dev or NULL if not found.
 */
struct virtio_crypto *virtcrypto_devmgr_get_first(void)
{
        struct virtio_crypto *dev = NULL;

        mutex_lock(&table_lock);
        if (!list_empty(&virtio_crypto_table))
                dev = list_first_entry(&virtio_crypto_table,
                                        struct virtio_crypto,
                                    list);
        mutex_unlock(&table_lock);
        return dev;
}

/*
 * virtcrypto_dev_in_use() - Check whether vcrypto_dev is currently in use
 * @vcrypto_dev: Pointer to virtio crypto device.
 *
 * To be used by virtio crypto device specific drivers.
 *
 * Return: 1 when device is in use, 0 otherwise.
 */
int virtcrypto_dev_in_use(struct virtio_crypto *vcrypto_dev)
{
        return atomic_read(&vcrypto_dev->ref_count) != 0;
}

/*
 * virtcrypto_dev_get() - Increment vcrypto_dev reference count
 * @vcrypto_dev: Pointer to virtio crypto device.
 *
 * Increment the vcrypto_dev refcount and if this is the first time
 * incrementing it during this period the vcrypto_dev is in use,
 * increment the module refcount too.
 * To be used by virtio crypto device specific drivers.
 *
 * Return: 0 when successful, EFAULT when fail to bump module refcount
 */
int virtcrypto_dev_get(struct virtio_crypto *vcrypto_dev)
{
        if (atomic_add_return(1, &vcrypto_dev->ref_count) == 1)
                if (!try_module_get(vcrypto_dev->owner))
                        return -EFAULT;
        return 0;
}

/*
 * virtcrypto_dev_put() - Decrement vcrypto_dev reference count
 * @vcrypto_dev: Pointer to virtio crypto device.
 *
 * Decrement the vcrypto_dev refcount and if this is the last time
 * decrementing it during this period the vcrypto_dev is in use,
 * decrement the module refcount too.
 * To be used by virtio crypto device specific drivers.
 *
 * Return: void
 */
void virtcrypto_dev_put(struct virtio_crypto *vcrypto_dev)
{
        if (atomic_sub_return(1, &vcrypto_dev->ref_count) == 0)
                module_put(vcrypto_dev->owner);
}

/*
 * virtcrypto_dev_started() - Check whether device has started
 * @vcrypto_dev: Pointer to virtio crypto device.
 *
 * To be used by virtio crypto device specific drivers.
 *
 * Return: 1 when the device has started, 0 otherwise
 */
int virtcrypto_dev_started(struct virtio_crypto *vcrypto_dev)
{
        return (vcrypto_dev->status & VIRTIO_CRYPTO_S_HW_READY);
}

/*
 * virtcrypto_get_dev_node() - Get vcrypto_dev on the node.
 * @node:  Node id the driver works.
 * @service: Crypto service that needs to be supported by the
 *            dev
 * @algo: The algorithm number that needs to be supported by the
 *        dev
 *
 * Function returns the virtio crypto device used fewest on the node,
 * and supports the given crypto service and algorithm.
 *
 * To be used by virtio crypto device specific drivers.
 *
 * Return: pointer to vcrypto_dev or NULL if not found.
 */
struct virtio_crypto *virtcrypto_get_dev_node(int node, uint32_t service,
                                              uint32_t algo)
{
        struct virtio_crypto *vcrypto_dev = NULL, *tmp_dev;
        unsigned long best = ~0;
        unsigned long ctr;

        mutex_lock(&table_lock);
        list_for_each_entry(tmp_dev, virtcrypto_devmgr_get_head(), list) {

                if ((node == dev_to_node(&tmp_dev->vdev->dev) ||
                     dev_to_node(&tmp_dev->vdev->dev) < 0) &&
                    virtcrypto_dev_started(tmp_dev) &&
                    virtcrypto_algo_is_supported(tmp_dev, service, algo)) {
                        ctr = atomic_read(&tmp_dev->ref_count);
                        if (best > ctr) {
                                vcrypto_dev = tmp_dev;
                                best = ctr;
                        }
                }
        }

        if (!vcrypto_dev) {
                pr_info("virtio_crypto: Could not find a device on node %d\n",
                                node);
                /* Get any started device */
                list_for_each_entry(tmp_dev,
                                virtcrypto_devmgr_get_head(), list) {
                        if (virtcrypto_dev_started(tmp_dev) &&
                            virtcrypto_algo_is_supported(tmp_dev,
                            service, algo)) {
                                vcrypto_dev = tmp_dev;
                                break;
                        }
                }
        }
        mutex_unlock(&table_lock);
        if (!vcrypto_dev)
                return NULL;

        virtcrypto_dev_get(vcrypto_dev);
        return vcrypto_dev;
}

/*
 * virtcrypto_dev_start() - Start virtio crypto device
 * @vcrypto:    Pointer to virtio crypto device.
 *
 * Function notifies all the registered services that the virtio crypto device
 * is ready to be used.
 * To be used by virtio crypto device specific drivers.
 *
 * Return: 0 on success, EFAULT when fail to register algorithms
 */
int virtcrypto_dev_start(struct virtio_crypto *vcrypto)
{
        if (virtio_crypto_algs_register(vcrypto)) {
                pr_err("virtio_crypto: Failed to register crypto algs\n");
                return -EFAULT;
        }

        return 0;
}

/*
 * virtcrypto_dev_stop() - Stop virtio crypto device
 * @vcrypto:    Pointer to virtio crypto device.
 *
 * Function notifies all the registered services that the virtio crypto device
 * is ready to be used.
 * To be used by virtio crypto device specific drivers.
 *
 * Return: void
 */
void virtcrypto_dev_stop(struct virtio_crypto *vcrypto)
{
        virtio_crypto_algs_unregister(vcrypto);
}

/*
 * vcrypto_algo_is_supported()
 * @vcrypto: Pointer to virtio crypto device.
 * @service: The bit number for service validate.
 *            See VIRTIO_CRYPTO_SERVICE_*
 * @algo : The bit number for the algorithm to validate.
 *
 *
 * Validate if the virtio crypto device supports a service and
 * algo.
 *
 * Return true if device supports a service and algo.
 */

bool virtcrypto_algo_is_supported(struct virtio_crypto *vcrypto,
                                  uint32_t service,
                                  uint32_t algo)
{
        uint32_t service_mask = 1u << service;
        uint32_t algo_mask = 0;
        bool low = true;

        if (algo > 31) {
                algo -= 32;
                low = false;
        }

        if (!(vcrypto->crypto_services & service_mask))
                return false;

        switch (service) {
        case VIRTIO_CRYPTO_SERVICE_CIPHER:
                if (low)
                        algo_mask = vcrypto->cipher_algo_l;
                else
                        algo_mask = vcrypto->cipher_algo_h;
                break;

        case VIRTIO_CRYPTO_SERVICE_HASH:
                algo_mask = vcrypto->hash_algo;
                break;

        case VIRTIO_CRYPTO_SERVICE_MAC:
                if (low)
                        algo_mask = vcrypto->mac_algo_l;
                else
                        algo_mask = vcrypto->mac_algo_h;
                break;

        case VIRTIO_CRYPTO_SERVICE_AEAD:
                algo_mask = vcrypto->aead_algo;
                break;
        }

        if (!(algo_mask & (1u << algo)))
                return false;

        return true;
}