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

#include <linux/module.h>
#include <linux/debugfs.h>
#include <linux/ntb.h>
#include <linux/pci.h>
#include <linux/radix-tree.h>
#include <linux/workqueue.h>

MODULE_LICENSE("Dual BSD/GPL");
MODULE_VERSION("0.1");
MODULE_AUTHOR("Logan Gunthorpe <logang@deltatee.com>");
MODULE_DESCRIPTION("Test for sending MSI interrupts over an NTB memory window");

static int num_irqs = 4;
module_param(num_irqs, int, 0644);
MODULE_PARM_DESC(num_irqs, "number of irqs to use");

struct ntb_msit_ctx {
	struct ntb_dev *ntb;
	struct dentry *dbgfs_dir;
	struct work_struct setup_work;

	struct ntb_msit_isr_ctx {
		int irq_idx;
		int irq_num;
		int occurrences;
		struct ntb_msit_ctx *nm;
		struct ntb_msi_desc desc;
	} *isr_ctx;

	struct ntb_msit_peer {
		struct ntb_msit_ctx *nm;
		int pidx;
		int num_irqs;
		struct completion init_comp;
		struct ntb_msi_desc *msi_desc;
	} peers[];
};

static struct dentry *ntb_msit_dbgfs_topdir;

static irqreturn_t ntb_msit_isr(int irq, void *dev)
{
	struct ntb_msit_isr_ctx *isr_ctx = dev;
	struct ntb_msit_ctx *nm = isr_ctx->nm;

	dev_dbg(&nm->ntb->dev, "Interrupt Occurred: %d",
		isr_ctx->irq_idx);

	isr_ctx->occurrences++;

	return IRQ_HANDLED;
}

static void ntb_msit_setup_work(struct work_struct *work)
{
	struct ntb_msit_ctx *nm = container_of(work, struct ntb_msit_ctx,
					       setup_work);
	int irq_count = 0;
	int irq;
	int ret;
	uintptr_t i;

	ret = ntb_msi_setup_mws(nm->ntb);
	if (ret) {
		dev_err(&nm->ntb->dev, "Unable to setup MSI windows: %d\n",
			ret);
		return;
	}

	for (i = 0; i < num_irqs; i++) {
		nm->isr_ctx[i].irq_idx = i;
		nm->isr_ctx[i].nm = nm;

		if (!nm->isr_ctx[i].irq_num) {
			irq = ntbm_msi_request_irq(nm->ntb, ntb_msit_isr,
						   KBUILD_MODNAME,
						   &nm->isr_ctx[i],
						   &nm->isr_ctx[i].desc);
			if (irq < 0)
				break;

			nm->isr_ctx[i].irq_num = irq;
		}

		ret = ntb_spad_write(nm->ntb, 2 * i + 1,
				     nm->isr_ctx[i].desc.addr_offset);
		if (ret)
			break;

		ret = ntb_spad_write(nm->ntb, 2 * i + 2,
				     nm->isr_ctx[i].desc.data);
		if (ret)
			break;

		irq_count++;
	}

	ntb_spad_write(nm->ntb, 0, irq_count);
	ntb_peer_db_set(nm->ntb, BIT(ntb_port_number(nm->ntb)));
}

static void ntb_msit_desc_changed(void *ctx)
{
	struct ntb_msit_ctx *nm = ctx;
	int i;

	dev_dbg(&nm->ntb->dev, "MSI Descriptors Changed\n");

	for (i = 0; i < num_irqs; i++) {
		ntb_spad_write(nm->ntb, 2 * i + 1,
			       nm->isr_ctx[i].desc.addr_offset);
		ntb_spad_write(nm->ntb, 2 * i + 2,
			       nm->isr_ctx[i].desc.data);
	}

	ntb_peer_db_set(nm->ntb, BIT(ntb_port_number(nm->ntb)));
}

static void ntb_msit_link_event(void *ctx)
{
	struct ntb_msit_ctx *nm = ctx;

	if (!ntb_link_is_up(nm->ntb, NULL, NULL))
		return;

	schedule_work(&nm->setup_work);
}

static void ntb_msit_copy_peer_desc(struct ntb_msit_ctx *nm, int peer)
{
	int i;
	struct ntb_msi_desc *desc = nm->peers[peer].msi_desc;
	int irq_count = nm->peers[peer].num_irqs;

	for (i = 0; i < irq_count; i++) {
		desc[i].addr_offset = ntb_peer_spad_read(nm->ntb, peer,
							 2 * i + 1);
		desc[i].data = ntb_peer_spad_read(nm->ntb, peer, 2 * i + 2);
	}

	dev_info(&nm->ntb->dev, "Found %d interrupts on peer %d\n",
		 irq_count, peer);

	complete_all(&nm->peers[peer].init_comp);
}

static void ntb_msit_db_event(void *ctx, int vec)
{
	struct ntb_msit_ctx *nm = ctx;
	struct ntb_msi_desc *desc;
	u64 peer_mask = ntb_db_read(nm->ntb);
	u32 irq_count;
	int peer;

	ntb_db_clear(nm->ntb, peer_mask);

	for (peer = 0; peer < sizeof(peer_mask) * 8; peer++) {
		if (!(peer_mask & BIT(peer)))
			continue;

		irq_count = ntb_peer_spad_read(nm->ntb, peer, 0);
		if (irq_count == -1)
			continue;

		desc = kcalloc(irq_count, sizeof(*desc), GFP_ATOMIC);
		if (!desc)
			continue;

		kfree(nm->peers[peer].msi_desc);
		nm->peers[peer].msi_desc = desc;
		nm->peers[peer].num_irqs = irq_count;

		ntb_msit_copy_peer_desc(nm, peer);
	}
}

static const struct ntb_ctx_ops ntb_msit_ops = {
	.link_event = ntb_msit_link_event,
	.db_event = ntb_msit_db_event,
};

static int ntb_msit_dbgfs_trigger(void *data, u64 idx)
{
	struct ntb_msit_peer *peer = data;

	if (idx >= peer->num_irqs)
		return -EINVAL;

	dev_dbg(&peer->nm->ntb->dev, "trigger irq %llu on peer %u\n",
		idx, peer->pidx);

	return ntb_msi_peer_trigger(peer->nm->ntb, peer->pidx,
				    &peer->msi_desc[idx]);
}

DEFINE_DEBUGFS_ATTRIBUTE(ntb_msit_trigger_fops, NULL,
			 ntb_msit_dbgfs_trigger, "%llu\n");

static int ntb_msit_dbgfs_port_get(void *data, u64 *port)
{
	struct ntb_msit_peer *peer = data;

	*port = ntb_peer_port_number(peer->nm->ntb, peer->pidx);

	return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(ntb_msit_port_fops, ntb_msit_dbgfs_port_get,
			 NULL, "%llu\n");

static int ntb_msit_dbgfs_count_get(void *data, u64 *count)
{
	struct ntb_msit_peer *peer = data;

	*count = peer->num_irqs;

	return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(ntb_msit_count_fops, ntb_msit_dbgfs_count_get,
			 NULL, "%llu\n");

static int ntb_msit_dbgfs_ready_get(void *data, u64 *ready)
{
	struct ntb_msit_peer *peer = data;

	*ready = try_wait_for_completion(&peer->init_comp);

	return 0;
}

static int ntb_msit_dbgfs_ready_set(void *data, u64 ready)
{
	struct ntb_msit_peer *peer = data;

	return wait_for_completion_interruptible(&peer->init_comp);
}

DEFINE_DEBUGFS_ATTRIBUTE(ntb_msit_ready_fops, ntb_msit_dbgfs_ready_get,
			 ntb_msit_dbgfs_ready_set, "%llu\n");

static int ntb_msit_dbgfs_occurrences_get(void *data, u64 *occurrences)
{
	struct ntb_msit_isr_ctx *isr_ctx = data;

	*occurrences = isr_ctx->occurrences;

	return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(ntb_msit_occurrences_fops,
			 ntb_msit_dbgfs_occurrences_get,
			 NULL, "%llu\n");

static int ntb_msit_dbgfs_local_port_get(void *data, u64 *port)
{
	struct ntb_msit_ctx *nm = data;

	*port = ntb_port_number(nm->ntb);

	return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(ntb_msit_local_port_fops,
			 ntb_msit_dbgfs_local_port_get,
			 NULL, "%llu\n");

static void ntb_msit_create_dbgfs(struct ntb_msit_ctx *nm)
{
	struct pci_dev *pdev = nm->ntb->pdev;
	char buf[32];
	int i;
	struct dentry *peer_dir;

	nm->dbgfs_dir = debugfs_create_dir(pci_name(pdev),
					   ntb_msit_dbgfs_topdir);
	debugfs_create_file("port", 0400, nm->dbgfs_dir, nm,
			    &ntb_msit_local_port_fops);

	for (i = 0; i < ntb_peer_port_count(nm->ntb); i++) {
		nm->peers[i].pidx = i;
		nm->peers[i].nm = nm;
		init_completion(&nm->peers[i].init_comp);

		snprintf(buf, sizeof(buf), "peer%d", i);
		peer_dir = debugfs_create_dir(buf, nm->dbgfs_dir);

		debugfs_create_file_unsafe("trigger", 0200, peer_dir,
					   &nm->peers[i],
					   &ntb_msit_trigger_fops);

		debugfs_create_file_unsafe("port", 0400, peer_dir,
					   &nm->peers[i], &ntb_msit_port_fops);

		debugfs_create_file_unsafe("count", 0400, peer_dir,
					   &nm->peers[i],
					   &ntb_msit_count_fops);

		debugfs_create_file_unsafe("ready", 0600, peer_dir,
					   &nm->peers[i],
					   &ntb_msit_ready_fops);
	}

	for (i = 0; i < num_irqs; i++) {
		snprintf(buf, sizeof(buf), "irq%d_occurrences", i);
		debugfs_create_file_unsafe(buf, 0400, nm->dbgfs_dir,
					   &nm->isr_ctx[i],
					   &ntb_msit_occurrences_fops);
	}
}

static void ntb_msit_remove_dbgfs(struct ntb_msit_ctx *nm)
{
	debugfs_remove_recursive(nm->dbgfs_dir);
}

static int ntb_msit_probe(struct ntb_client *client, struct ntb_dev *ntb)
{
	struct ntb_msit_ctx *nm;
	int peers;
	int ret;

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

	if (ntb_spad_is_unsafe(ntb) || ntb_spad_count(ntb) < 2 * num_irqs + 1) {
		dev_err(&ntb->dev, "NTB MSI test requires at least %d spads for %d irqs\n",
			2 * num_irqs + 1, num_irqs);
		return -EFAULT;
	}

	ret = ntb_spad_write(ntb, 0, -1);
	if (ret) {
		dev_err(&ntb->dev, "Unable to write spads: %d\n", ret);
		return ret;
	}

	ret = ntb_db_clear_mask(ntb, GENMASK(peers - 1, 0));
	if (ret) {
		dev_err(&ntb->dev, "Unable to clear doorbell mask: %d\n", ret);
		return ret;
	}

	ret = ntb_msi_init(ntb, ntb_msit_desc_changed);
	if (ret) {
		dev_err(&ntb->dev, "Unable to initialize MSI library: %d\n",
			ret);
		return ret;
	}

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

	nm->isr_ctx = devm_kcalloc(&ntb->dev, num_irqs, sizeof(*nm->isr_ctx),
				   GFP_KERNEL);
	if (!nm->isr_ctx)
		return -ENOMEM;

	INIT_WORK(&nm->setup_work, ntb_msit_setup_work);
	nm->ntb = ntb;

	ntb_msit_create_dbgfs(nm);

	ret = ntb_set_ctx(ntb, nm, &ntb_msit_ops);
	if (ret)
		goto remove_dbgfs;

	if (!nm->isr_ctx)
		goto remove_dbgfs;

	ntb_link_enable(ntb, NTB_SPEED_AUTO, NTB_WIDTH_AUTO);

	return 0;

remove_dbgfs:
	ntb_msit_remove_dbgfs(nm);
	devm_kfree(&ntb->dev, nm->isr_ctx);
	devm_kfree(&ntb->dev, nm);
	return ret;
}

static void ntb_msit_remove(struct ntb_client *client, struct ntb_dev *ntb)
{
	struct ntb_msit_ctx *nm = ntb->ctx;
	int i;

	ntb_link_disable(ntb);
	ntb_db_set_mask(ntb, ntb_db_valid_mask(ntb));
	ntb_msi_clear_mws(ntb);

	for (i = 0; i < ntb_peer_port_count(ntb); i++)
		kfree(nm->peers[i].msi_desc);

	ntb_clear_ctx(ntb);
	ntb_msit_remove_dbgfs(nm);
}

static struct ntb_client ntb_msit_client = {
	.ops = {
		.probe = ntb_msit_probe,
		.remove = ntb_msit_remove
	}
};

static int __init ntb_msit_init(void)
{
	int ret;

	if (debugfs_initialized())
		ntb_msit_dbgfs_topdir = debugfs_create_dir(KBUILD_MODNAME,
							   NULL);

	ret = ntb_register_client(&ntb_msit_client);
	if (ret)
		debugfs_remove_recursive(ntb_msit_dbgfs_topdir);

	return ret;
}
module_init(ntb_msit_init);

static void __exit ntb_msit_exit(void)
{
	ntb_unregister_client(&ntb_msit_client);
	debugfs_remove_recursive(ntb_msit_dbgfs_topdir);
}
module_exit(ntb_msit_exit);