// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)

#include <linux/irq.h>
#include <linux/module.h>
#include <linux/ntb.h>
#include <linux/msi.h>
#include <linux/pci.h>

struct ntb_msi {
        u64 base_addr;
        u64 end_addr;

        void (*desc_changed)(void *ctx);

        u32 __iomem *peer_mws[];
};

/**
 * ntb_msi_init() - Initialize the MSI context
 * @ntb:        NTB device context
 *
 * This function must be called before any other ntb_msi function.
 * It initializes the context for MSI operations and maps
 * the peer memory windows.
 *
 * This function reserves the last N outbound memory windows (where N
 * is the number of peers).
 *
 * Return: Zero on success, otherwise a negative error number.
 */
int ntb_msi_init(struct ntb_dev *ntb,
                 void (*desc_changed)(void *ctx))
{
        phys_addr_t mw_phys_addr;
        resource_size_t mw_size;
        int peer_widx;
        int peers;
        int ret;
        int i;

        peers = ntb_peer_port_count(ntb);
        if (peers <= 0)
                return -EINVAL;

        ntb->msi = devm_kzalloc(&ntb->dev, struct_size(ntb->msi, peer_mws, peers),
                                GFP_KERNEL);
        if (!ntb->msi)
                return -ENOMEM;

        ntb->msi->desc_changed = desc_changed;

        for (i = 0; i < peers; i++) {
                peer_widx = ntb_peer_mw_count(ntb) - 1 - i;

                ret = ntb_peer_mw_get_addr(ntb, peer_widx, &mw_phys_addr,
                                           &mw_size);
                if (ret)
                        goto unroll;

                ntb->msi->peer_mws[i] = devm_ioremap(&ntb->dev, mw_phys_addr,
                                                     mw_size);
                if (!ntb->msi->peer_mws[i]) {
                        ret = -EFAULT;
                        goto unroll;
                }
        }

        return 0;

unroll:
        for (i = 0; i < peers; i++)
                if (ntb->msi->peer_mws[i])
                        devm_iounmap(&ntb->dev, ntb->msi->peer_mws[i]);

        devm_kfree(&ntb->dev, ntb->msi);
        ntb->msi = NULL;
        return ret;
}
EXPORT_SYMBOL(ntb_msi_init);

/**
 * ntb_msi_setup_mws() - Initialize the MSI inbound memory windows
 * @ntb:        NTB device context
 *
 * This function sets up the required inbound memory windows. It should be
 * called from a work function after a link up event.
 *
 * Over the entire network, this function will reserves the last N
 * inbound memory windows for each peer (where N is the number of peers).
 *
 * ntb_msi_init() must be called before this function.
 *
 * Return: Zero on success, otherwise a negative error number.
 */
int ntb_msi_setup_mws(struct ntb_dev *ntb)
{
        struct msi_desc *desc;
        u64 addr;
        int peer, peer_widx;
        resource_size_t addr_align, size_align, size_max;
        resource_size_t mw_size = SZ_32K;
        resource_size_t mw_min_size = mw_size;
        int i;
        int ret;

        if (!ntb->msi)
                return -EINVAL;

        scoped_guard (msi_descs_lock, &ntb->pdev->dev) {
                desc = msi_first_desc(&ntb->pdev->dev, MSI_DESC_ASSOCIATED);
                addr = desc->msg.address_lo + ((uint64_t)desc->msg.address_hi << 32);
        }

        for (peer = 0; peer < ntb_peer_port_count(ntb); peer++) {
                peer_widx = ntb_peer_highest_mw_idx(ntb, peer);
                if (peer_widx < 0)
                        return peer_widx;

                ret = ntb_mw_get_align(ntb, peer, peer_widx, &addr_align,
                                       NULL, NULL);
                if (ret)
                        return ret;

                addr &= ~(addr_align - 1);
        }

        for (peer = 0; peer < ntb_peer_port_count(ntb); peer++) {
                peer_widx = ntb_peer_highest_mw_idx(ntb, peer);
                if (peer_widx < 0) {
                        ret = peer_widx;
                        goto error_out;
                }

                ret = ntb_mw_get_align(ntb, peer, peer_widx, NULL,
                                       &size_align, &size_max);
                if (ret)
                        goto error_out;

                mw_size = round_up(mw_size, size_align);
                mw_size = max(mw_size, size_max);
                if (mw_size < mw_min_size)
                        mw_min_size = mw_size;

                ret = ntb_mw_set_trans(ntb, peer, peer_widx,
                                       addr, mw_size);
                if (ret)
                        goto error_out;
        }

        ntb->msi->base_addr = addr;
        ntb->msi->end_addr = addr + mw_min_size;

        return 0;

error_out:
        for (i = 0; i < peer; i++) {
                peer_widx = ntb_peer_highest_mw_idx(ntb, peer);
                if (peer_widx < 0)
                        continue;

                ntb_mw_clear_trans(ntb, i, peer_widx);
        }

        return ret;
}
EXPORT_SYMBOL(ntb_msi_setup_mws);

/**
 * ntb_msi_clear_mws() - Clear all inbound memory windows
 * @ntb:        NTB device context
 *
 * This function tears down the resources used by ntb_msi_setup_mws().
 */
void ntb_msi_clear_mws(struct ntb_dev *ntb)
{
        int peer;
        int peer_widx;

        for (peer = 0; peer < ntb_peer_port_count(ntb); peer++) {
                peer_widx = ntb_peer_highest_mw_idx(ntb, peer);
                if (peer_widx < 0)
                        continue;

                ntb_mw_clear_trans(ntb, peer, peer_widx);
        }
}
EXPORT_SYMBOL(ntb_msi_clear_mws);

struct ntb_msi_devres {
        struct ntb_dev *ntb;
        struct msi_desc *entry;
        struct ntb_msi_desc *msi_desc;
};

static int ntb_msi_set_desc(struct ntb_dev *ntb, struct msi_desc *entry,
                            struct ntb_msi_desc *msi_desc)
{
        u64 addr;

        addr = entry->msg.address_lo +
                ((uint64_t)entry->msg.address_hi << 32);

        if (addr < ntb->msi->base_addr || addr >= ntb->msi->end_addr) {
                dev_warn_once(&ntb->dev,
                              "IRQ %d: MSI Address not within the memory window (%llx, [%llx %llx])\n",
                              entry->irq, addr, ntb->msi->base_addr,
                              ntb->msi->end_addr);
                return -EFAULT;
        }

        msi_desc->addr_offset = addr - ntb->msi->base_addr;
        msi_desc->data = entry->msg.data;

        return 0;
}

static void ntb_msi_write_msg(struct msi_desc *entry, void *data)
{
        struct ntb_msi_devres *dr = data;

        WARN_ON(ntb_msi_set_desc(dr->ntb, entry, dr->msi_desc));

        if (dr->ntb->msi->desc_changed)
                dr->ntb->msi->desc_changed(dr->ntb->ctx);
}

static void ntbm_msi_callback_release(struct device *dev, void *res)
{
        struct ntb_msi_devres *dr = res;

        dr->entry->write_msi_msg = NULL;
        dr->entry->write_msi_msg_data = NULL;
}

static int ntbm_msi_setup_callback(struct ntb_dev *ntb, struct msi_desc *entry,
                                   struct ntb_msi_desc *msi_desc)
{
        struct ntb_msi_devres *dr;

        dr = devres_alloc(ntbm_msi_callback_release,
                          sizeof(struct ntb_msi_devres), GFP_KERNEL);
        if (!dr)
                return -ENOMEM;

        dr->ntb = ntb;
        dr->entry = entry;
        dr->msi_desc = msi_desc;

        devres_add(&ntb->dev, dr);

        dr->entry->write_msi_msg = ntb_msi_write_msg;
        dr->entry->write_msi_msg_data = dr;

        return 0;
}

/**
 * ntbm_msi_request_threaded_irq() - allocate an MSI interrupt
 * @ntb:        NTB device context
 * @handler:    Function to be called when the IRQ occurs
 * @thread_fn:  Function to be called in a threaded interrupt context. NULL
 *              for clients which handle everything in @handler
 * @name:    An ascii name for the claiming device, dev_name(dev) if NULL
 * @dev_id:     A cookie passed back to the handler function
 * @msi_desc:   MSI descriptor data which triggers the interrupt
 *
 * This function assigns an interrupt handler to an unused
 * MSI interrupt and returns the descriptor used to trigger
 * it. The descriptor can then be sent to a peer to trigger
 * the interrupt.
 *
 * The interrupt resource is managed with devres so it will
 * be automatically freed when the NTB device is torn down.
 *
 * If an IRQ allocated with this function needs to be freed
 * separately, ntbm_free_irq() must be used.
 *
 * Return: IRQ number assigned on success, otherwise a negative error number.
 */
int ntbm_msi_request_threaded_irq(struct ntb_dev *ntb, irq_handler_t handler,
                                  irq_handler_t thread_fn,
                                  const char *name, void *dev_id,
                                  struct ntb_msi_desc *msi_desc)
{
        struct device *dev = &ntb->pdev->dev;
        struct msi_desc *entry;
        int ret;

        if (!ntb->msi)
                return -EINVAL;

        guard(msi_descs_lock)(dev);
        msi_for_each_desc(entry, dev, MSI_DESC_ASSOCIATED) {
                if (irq_has_action(entry->irq))
                        continue;

                ret = devm_request_threaded_irq(&ntb->dev, entry->irq, handler,
                                                thread_fn, 0, name, dev_id);
                if (ret)
                        continue;

                if (ntb_msi_set_desc(ntb, entry, msi_desc)) {
                        devm_free_irq(&ntb->dev, entry->irq, dev_id);
                        continue;
                }

                ret = ntbm_msi_setup_callback(ntb, entry, msi_desc);
                if (ret) {
                        devm_free_irq(&ntb->dev, entry->irq, dev_id);
                        return ret;
                }
                return entry->irq;
        }
        return -ENODEV;
}
EXPORT_SYMBOL(ntbm_msi_request_threaded_irq);

/**
 * ntb_msi_peer_trigger() - Trigger an interrupt handler on a peer
 * @ntb:        NTB device context
 * @peer:       Peer index
 * @desc:       MSI descriptor data which triggers the interrupt
 *
 * This function triggers an interrupt on a peer. It requires
 * the descriptor structure to have been passed from that peer
 * by some other means.
 *
 * Return: Zero on success, otherwise a negative error number.
 */
int ntb_msi_peer_trigger(struct ntb_dev *ntb, int peer,
                         struct ntb_msi_desc *desc)
{
        int idx;

        if (!ntb->msi)
                return -EINVAL;

        idx = desc->addr_offset / sizeof(*ntb->msi->peer_mws[peer]);

        iowrite32(desc->data, &ntb->msi->peer_mws[peer][idx]);

        return 0;
}
EXPORT_SYMBOL(ntb_msi_peer_trigger);