// SPDX-License-Identifier: GPL-2.0
/**
 * Host side endpoint driver to implement Non-Transparent Bridge functionality
 *
 * Copyright (C) 2020 Texas Instruments
 * Author: Kishon Vijay Abraham I <kishon@ti.com>
 */

#include <linux/delay.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/ntb.h>

#define NTB_EPF_COMMAND		0x0
#define CMD_CONFIGURE_DOORBELL	1
#define CMD_TEARDOWN_DOORBELL	2
#define CMD_CONFIGURE_MW	3
#define CMD_TEARDOWN_MW		4
#define CMD_LINK_UP		5
#define CMD_LINK_DOWN		6

#define NTB_EPF_ARGUMENT	0x4
#define MSIX_ENABLE		BIT(16)

#define NTB_EPF_CMD_STATUS	0x8
#define COMMAND_STATUS_OK	1
#define COMMAND_STATUS_ERROR	2

#define NTB_EPF_LINK_STATUS	0x0A
#define LINK_STATUS_UP		BIT(0)

#define NTB_EPF_TOPOLOGY	0x0C
#define NTB_EPF_LOWER_ADDR	0x10
#define NTB_EPF_UPPER_ADDR	0x14
#define NTB_EPF_LOWER_SIZE	0x18
#define NTB_EPF_UPPER_SIZE	0x1C
#define NTB_EPF_MW_COUNT	0x20
#define NTB_EPF_MW1_OFFSET	0x24
#define NTB_EPF_SPAD_OFFSET	0x28
#define NTB_EPF_SPAD_COUNT	0x2C
#define NTB_EPF_DB_ENTRY_SIZE	0x30
#define NTB_EPF_DB_DATA(n)	(0x34 + (n) * 4)
#define NTB_EPF_DB_OFFSET(n)	(0xB4 + (n) * 4)

#define NTB_EPF_MIN_DB_COUNT	3
#define NTB_EPF_MAX_DB_COUNT	31
#define NTB_EPF_MW_OFFSET	2

#define NTB_EPF_COMMAND_TIMEOUT	1000 /* 1 Sec */

enum pci_barno {
	BAR_0,
	BAR_1,
	BAR_2,
	BAR_3,
	BAR_4,
	BAR_5,
};

struct ntb_epf_dev {
	struct ntb_dev ntb;
	struct device *dev;
	/* Mutex to protect providing commands to NTB EPF */
	struct mutex cmd_lock;

	enum pci_barno ctrl_reg_bar;
	enum pci_barno peer_spad_reg_bar;
	enum pci_barno db_reg_bar;

	unsigned int mw_count;
	unsigned int spad_count;
	unsigned int db_count;

	void __iomem *ctrl_reg;
	void __iomem *db_reg;
	void __iomem *peer_spad_reg;

	unsigned int self_spad;
	unsigned int peer_spad;

	int db_val;
	u64 db_valid_mask;
};

#define ntb_ndev(__ntb) container_of(__ntb, struct ntb_epf_dev, ntb)

struct ntb_epf_data {
	/* BAR that contains both control region and self spad region */
	enum pci_barno ctrl_reg_bar;
	/* BAR that contains peer spad region */
	enum pci_barno peer_spad_reg_bar;
	/* BAR that contains Doorbell region and Memory window '1' */
	enum pci_barno db_reg_bar;
};

static int ntb_epf_send_command(struct ntb_epf_dev *ndev, u32 command,
				u32 argument)
{
	ktime_t timeout;
	bool timedout;
	int ret = 0;
	u32 status;

	mutex_lock(&ndev->cmd_lock);
	writel(argument, ndev->ctrl_reg + NTB_EPF_ARGUMENT);
	writel(command, ndev->ctrl_reg + NTB_EPF_COMMAND);

	timeout = ktime_add_ms(ktime_get(), NTB_EPF_COMMAND_TIMEOUT);
	while (1) {
		timedout = ktime_after(ktime_get(), timeout);
		status = readw(ndev->ctrl_reg + NTB_EPF_CMD_STATUS);

		if (status == COMMAND_STATUS_ERROR) {
			ret = -EINVAL;
			break;
		}

		if (status == COMMAND_STATUS_OK)
			break;

		if (WARN_ON(timedout)) {
			ret = -ETIMEDOUT;
			break;
		}

		usleep_range(5, 10);
	}

	writew(0, ndev->ctrl_reg + NTB_EPF_CMD_STATUS);
	mutex_unlock(&ndev->cmd_lock);

	return ret;
}

static int ntb_epf_mw_to_bar(struct ntb_epf_dev *ndev, int idx)
{
	struct device *dev = ndev->dev;

	if (idx < 0 || idx > ndev->mw_count) {
		dev_err(dev, "Unsupported Memory Window index %d\n", idx);
		return -EINVAL;
	}

	return idx + 2;
}

static int ntb_epf_mw_count(struct ntb_dev *ntb, int pidx)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
	struct device *dev = ndev->dev;

	if (pidx != NTB_DEF_PEER_IDX) {
		dev_err(dev, "Unsupported Peer ID %d\n", pidx);
		return -EINVAL;
	}

	return ndev->mw_count;
}

static int ntb_epf_mw_get_align(struct ntb_dev *ntb, int pidx, int idx,
				resource_size_t *addr_align,
				resource_size_t *size_align,
				resource_size_t *size_max)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
	struct device *dev = ndev->dev;
	int bar;

	if (pidx != NTB_DEF_PEER_IDX) {
		dev_err(dev, "Unsupported Peer ID %d\n", pidx);
		return -EINVAL;
	}

	bar = ntb_epf_mw_to_bar(ndev, idx);
	if (bar < 0)
		return bar;

	if (addr_align)
		*addr_align = SZ_4K;

	if (size_align)
		*size_align = 1;

	if (size_max)
		*size_max = pci_resource_len(ndev->ntb.pdev, bar);

	return 0;
}

static u64 ntb_epf_link_is_up(struct ntb_dev *ntb,
			      enum ntb_speed *speed,
			      enum ntb_width *width)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
	u32 status;

	status = readw(ndev->ctrl_reg + NTB_EPF_LINK_STATUS);

	return status & LINK_STATUS_UP;
}

static u32 ntb_epf_spad_read(struct ntb_dev *ntb, int idx)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
	struct device *dev = ndev->dev;
	u32 offset;

	if (idx < 0 || idx >= ndev->spad_count) {
		dev_err(dev, "READ: Invalid ScratchPad Index %d\n", idx);
		return 0;
	}

	offset = readl(ndev->ctrl_reg + NTB_EPF_SPAD_OFFSET);
	offset += (idx << 2);

	return readl(ndev->ctrl_reg + offset);
}

static int ntb_epf_spad_write(struct ntb_dev *ntb,
			      int idx, u32 val)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
	struct device *dev = ndev->dev;
	u32 offset;

	if (idx < 0 || idx >= ndev->spad_count) {
		dev_err(dev, "WRITE: Invalid ScratchPad Index %d\n", idx);
		return -EINVAL;
	}

	offset = readl(ndev->ctrl_reg + NTB_EPF_SPAD_OFFSET);
	offset += (idx << 2);
	writel(val, ndev->ctrl_reg + offset);

	return 0;
}

static u32 ntb_epf_peer_spad_read(struct ntb_dev *ntb, int pidx, int idx)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
	struct device *dev = ndev->dev;
	u32 offset;

	if (pidx != NTB_DEF_PEER_IDX) {
		dev_err(dev, "Unsupported Peer ID %d\n", pidx);
		return -EINVAL;
	}

	if (idx < 0 || idx >= ndev->spad_count) {
		dev_err(dev, "WRITE: Invalid Peer ScratchPad Index %d\n", idx);
		return -EINVAL;
	}

	offset = (idx << 2);
	return readl(ndev->peer_spad_reg + offset);
}

static int ntb_epf_peer_spad_write(struct ntb_dev *ntb, int pidx,
				   int idx, u32 val)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
	struct device *dev = ndev->dev;
	u32 offset;

	if (pidx != NTB_DEF_PEER_IDX) {
		dev_err(dev, "Unsupported Peer ID %d\n", pidx);
		return -EINVAL;
	}

	if (idx < 0 || idx >= ndev->spad_count) {
		dev_err(dev, "WRITE: Invalid Peer ScratchPad Index %d\n", idx);
		return -EINVAL;
	}

	offset = (idx << 2);
	writel(val, ndev->peer_spad_reg + offset);

	return 0;
}

static int ntb_epf_link_enable(struct ntb_dev *ntb,
			       enum ntb_speed max_speed,
			       enum ntb_width max_width)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
	struct device *dev = ndev->dev;
	int ret;

	ret = ntb_epf_send_command(ndev, CMD_LINK_UP, 0);
	if (ret) {
		dev_err(dev, "Fail to enable link\n");
		return ret;
	}

	return 0;
}

static int ntb_epf_link_disable(struct ntb_dev *ntb)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
	struct device *dev = ndev->dev;
	int ret;

	ret = ntb_epf_send_command(ndev, CMD_LINK_DOWN, 0);
	if (ret) {
		dev_err(dev, "Fail to disable link\n");
		return ret;
	}

	return 0;
}

static irqreturn_t ntb_epf_vec_isr(int irq, void *dev)
{
	struct ntb_epf_dev *ndev = dev;
	int irq_no;

	irq_no = irq - pci_irq_vector(ndev->ntb.pdev, 0);
	ndev->db_val = irq_no + 1;

	if (irq_no == 0)
		ntb_link_event(&ndev->ntb);
	else
		ntb_db_event(&ndev->ntb, irq_no);

	return IRQ_HANDLED;
}

static int ntb_epf_init_isr(struct ntb_epf_dev *ndev, int msi_min, int msi_max)
{
	struct pci_dev *pdev = ndev->ntb.pdev;
	struct device *dev = ndev->dev;
	u32 argument = MSIX_ENABLE;
	int irq;
	int ret;
	int i;

	irq = pci_alloc_irq_vectors(pdev, msi_min, msi_max, PCI_IRQ_MSIX);
	if (irq < 0) {
		dev_dbg(dev, "Failed to get MSIX interrupts\n");
		irq = pci_alloc_irq_vectors(pdev, msi_min, msi_max,
					    PCI_IRQ_MSI);
		if (irq < 0) {
			dev_err(dev, "Failed to get MSI interrupts\n");
			return irq;
		}
		argument &= ~MSIX_ENABLE;
	}

	for (i = 0; i < irq; i++) {
		ret = request_irq(pci_irq_vector(pdev, i), ntb_epf_vec_isr,
				  0, "ntb_epf", ndev);
		if (ret) {
			dev_err(dev, "Failed to request irq\n");
			goto err_request_irq;
		}
	}

	ndev->db_count = irq - 1;

	ret = ntb_epf_send_command(ndev, CMD_CONFIGURE_DOORBELL,
				   argument | irq);
	if (ret) {
		dev_err(dev, "Failed to configure doorbell\n");
		goto err_configure_db;
	}

	return 0;

err_configure_db:
	for (i = 0; i < ndev->db_count + 1; i++)
		free_irq(pci_irq_vector(pdev, i), ndev);

err_request_irq:
	pci_free_irq_vectors(pdev);

	return ret;
}

static int ntb_epf_peer_mw_count(struct ntb_dev *ntb)
{
	return ntb_ndev(ntb)->mw_count;
}

static int ntb_epf_spad_count(struct ntb_dev *ntb)
{
	return ntb_ndev(ntb)->spad_count;
}

static u64 ntb_epf_db_valid_mask(struct ntb_dev *ntb)
{
	return ntb_ndev(ntb)->db_valid_mask;
}

static int ntb_epf_db_set_mask(struct ntb_dev *ntb, u64 db_bits)
{
	return 0;
}

static int ntb_epf_mw_set_trans(struct ntb_dev *ntb, int pidx, int idx,
				dma_addr_t addr, resource_size_t size)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
	struct device *dev = ndev->dev;
	resource_size_t mw_size;
	int bar;

	if (pidx != NTB_DEF_PEER_IDX) {
		dev_err(dev, "Unsupported Peer ID %d\n", pidx);
		return -EINVAL;
	}

	bar = idx + NTB_EPF_MW_OFFSET;

	mw_size = pci_resource_len(ntb->pdev, bar);

	if (size > mw_size) {
		dev_err(dev, "Size:%pa is greater than the MW size %pa\n",
			&size, &mw_size);
		return -EINVAL;
	}

	writel(lower_32_bits(addr), ndev->ctrl_reg + NTB_EPF_LOWER_ADDR);
	writel(upper_32_bits(addr), ndev->ctrl_reg + NTB_EPF_UPPER_ADDR);
	writel(lower_32_bits(size), ndev->ctrl_reg + NTB_EPF_LOWER_SIZE);
	writel(upper_32_bits(size), ndev->ctrl_reg + NTB_EPF_UPPER_SIZE);
	ntb_epf_send_command(ndev, CMD_CONFIGURE_MW, idx);

	return 0;
}

static int ntb_epf_mw_clear_trans(struct ntb_dev *ntb, int pidx, int idx)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
	struct device *dev = ndev->dev;
	int ret = 0;

	ntb_epf_send_command(ndev, CMD_TEARDOWN_MW, idx);
	if (ret)
		dev_err(dev, "Failed to teardown memory window\n");

	return ret;
}

static int ntb_epf_peer_mw_get_addr(struct ntb_dev *ntb, int idx,
				    phys_addr_t *base, resource_size_t *size)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
	u32 offset = 0;
	int bar;

	if (idx == 0)
		offset = readl(ndev->ctrl_reg + NTB_EPF_MW1_OFFSET);

	bar = idx + NTB_EPF_MW_OFFSET;

	if (base)
		*base = pci_resource_start(ndev->ntb.pdev, bar) + offset;

	if (size)
		*size = pci_resource_len(ndev->ntb.pdev, bar) - offset;

	return 0;
}

static int ntb_epf_peer_db_set(struct ntb_dev *ntb, u64 db_bits)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
	u32 interrupt_num = ffs(db_bits) + 1;
	struct device *dev = ndev->dev;
	u32 db_entry_size;
	u32 db_offset;
	u32 db_data;

	if (interrupt_num > ndev->db_count) {
		dev_err(dev, "DB interrupt %d greater than Max Supported %d\n",
			interrupt_num, ndev->db_count);
		return -EINVAL;
	}

	db_entry_size = readl(ndev->ctrl_reg + NTB_EPF_DB_ENTRY_SIZE);

	db_data = readl(ndev->ctrl_reg + NTB_EPF_DB_DATA(interrupt_num));
	db_offset = readl(ndev->ctrl_reg + NTB_EPF_DB_OFFSET(interrupt_num));
	writel(db_data, ndev->db_reg + (db_entry_size * interrupt_num) +
	       db_offset);

	return 0;
}

static u64 ntb_epf_db_read(struct ntb_dev *ntb)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);

	return ndev->db_val;
}

static int ntb_epf_db_clear_mask(struct ntb_dev *ntb, u64 db_bits)
{
	return 0;
}

static int ntb_epf_db_clear(struct ntb_dev *ntb, u64 db_bits)
{
	struct ntb_epf_dev *ndev = ntb_ndev(ntb);

	ndev->db_val = 0;

	return 0;
}

static const struct ntb_dev_ops ntb_epf_ops = {
	.mw_count		= ntb_epf_mw_count,
	.spad_count		= ntb_epf_spad_count,
	.peer_mw_count		= ntb_epf_peer_mw_count,
	.db_valid_mask		= ntb_epf_db_valid_mask,
	.db_set_mask		= ntb_epf_db_set_mask,
	.mw_set_trans		= ntb_epf_mw_set_trans,
	.mw_clear_trans		= ntb_epf_mw_clear_trans,
	.peer_mw_get_addr	= ntb_epf_peer_mw_get_addr,
	.link_enable		= ntb_epf_link_enable,
	.spad_read		= ntb_epf_spad_read,
	.spad_write		= ntb_epf_spad_write,
	.peer_spad_read		= ntb_epf_peer_spad_read,
	.peer_spad_write	= ntb_epf_peer_spad_write,
	.peer_db_set		= ntb_epf_peer_db_set,
	.db_read		= ntb_epf_db_read,
	.mw_get_align		= ntb_epf_mw_get_align,
	.link_is_up		= ntb_epf_link_is_up,
	.db_clear_mask		= ntb_epf_db_clear_mask,
	.db_clear		= ntb_epf_db_clear,
	.link_disable		= ntb_epf_link_disable,
};

static inline void ntb_epf_init_struct(struct ntb_epf_dev *ndev,
				       struct pci_dev *pdev)
{
	ndev->ntb.pdev = pdev;
	ndev->ntb.topo = NTB_TOPO_NONE;
	ndev->ntb.ops = &ntb_epf_ops;
}

static int ntb_epf_init_dev(struct ntb_epf_dev *ndev)
{
	struct device *dev = ndev->dev;
	int ret;

	/* One Link interrupt and rest doorbell interrupt */
	ret = ntb_epf_init_isr(ndev, NTB_EPF_MIN_DB_COUNT + 1,
			       NTB_EPF_MAX_DB_COUNT + 1);
	if (ret) {
		dev_err(dev, "Failed to init ISR\n");
		return ret;
	}

	ndev->db_valid_mask = BIT_ULL(ndev->db_count) - 1;
	ndev->mw_count = readl(ndev->ctrl_reg + NTB_EPF_MW_COUNT);
	ndev->spad_count = readl(ndev->ctrl_reg + NTB_EPF_SPAD_COUNT);

	return 0;
}

static int ntb_epf_init_pci(struct ntb_epf_dev *ndev,
			    struct pci_dev *pdev)
{
	struct device *dev = ndev->dev;
	int ret;

	pci_set_drvdata(pdev, ndev);

	ret = pci_enable_device(pdev);
	if (ret) {
		dev_err(dev, "Cannot enable PCI device\n");
		goto err_pci_enable;
	}

	ret = pci_request_regions(pdev, "ntb");
	if (ret) {
		dev_err(dev, "Cannot obtain PCI resources\n");
		goto err_pci_regions;
	}

	pci_set_master(pdev);

	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
	if (ret) {
		ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
		if (ret) {
			dev_err(dev, "Cannot set DMA mask\n");
			goto err_dma_mask;
		}
		dev_warn(&pdev->dev, "Cannot DMA highmem\n");
	}

	ndev->ctrl_reg = pci_iomap(pdev, ndev->ctrl_reg_bar, 0);
	if (!ndev->ctrl_reg) {
		ret = -EIO;
		goto err_dma_mask;
	}

	ndev->peer_spad_reg = pci_iomap(pdev, ndev->peer_spad_reg_bar, 0);
	if (!ndev->peer_spad_reg) {
		ret = -EIO;
		goto err_dma_mask;
	}

	ndev->db_reg = pci_iomap(pdev, ndev->db_reg_bar, 0);
	if (!ndev->db_reg) {
		ret = -EIO;
		goto err_dma_mask;
	}

	return 0;

err_dma_mask:
	pci_clear_master(pdev);

err_pci_regions:
	pci_disable_device(pdev);

err_pci_enable:
	pci_set_drvdata(pdev, NULL);

	return ret;
}

static void ntb_epf_deinit_pci(struct ntb_epf_dev *ndev)
{
	struct pci_dev *pdev = ndev->ntb.pdev;

	pci_iounmap(pdev, ndev->ctrl_reg);
	pci_iounmap(pdev, ndev->peer_spad_reg);
	pci_iounmap(pdev, ndev->db_reg);

	pci_clear_master(pdev);
	pci_release_regions(pdev);
	pci_disable_device(pdev);
	pci_set_drvdata(pdev, NULL);
}

static void ntb_epf_cleanup_isr(struct ntb_epf_dev *ndev)
{
	struct pci_dev *pdev = ndev->ntb.pdev;
	int i;

	ntb_epf_send_command(ndev, CMD_TEARDOWN_DOORBELL, ndev->db_count + 1);

	for (i = 0; i < ndev->db_count + 1; i++)
		free_irq(pci_irq_vector(pdev, i), ndev);
	pci_free_irq_vectors(pdev);
}

static int ntb_epf_pci_probe(struct pci_dev *pdev,
			     const struct pci_device_id *id)
{
	enum pci_barno peer_spad_reg_bar = BAR_1;
	enum pci_barno ctrl_reg_bar = BAR_0;
	enum pci_barno db_reg_bar = BAR_2;
	struct device *dev = &pdev->dev;
	struct ntb_epf_data *data;
	struct ntb_epf_dev *ndev;
	int ret;

	if (pci_is_bridge(pdev))
		return -ENODEV;

	ndev = devm_kzalloc(dev, sizeof(*ndev), GFP_KERNEL);
	if (!ndev)
		return -ENOMEM;

	data = (struct ntb_epf_data *)id->driver_data;
	if (data) {
		if (data->peer_spad_reg_bar)
			peer_spad_reg_bar = data->peer_spad_reg_bar;
		if (data->ctrl_reg_bar)
			ctrl_reg_bar = data->ctrl_reg_bar;
		if (data->db_reg_bar)
			db_reg_bar = data->db_reg_bar;
	}

	ndev->peer_spad_reg_bar = peer_spad_reg_bar;
	ndev->ctrl_reg_bar = ctrl_reg_bar;
	ndev->db_reg_bar = db_reg_bar;
	ndev->dev = dev;

	ntb_epf_init_struct(ndev, pdev);
	mutex_init(&ndev->cmd_lock);

	ret = ntb_epf_init_pci(ndev, pdev);
	if (ret) {
		dev_err(dev, "Failed to init PCI\n");
		return ret;
	}

	ret = ntb_epf_init_dev(ndev);
	if (ret) {
		dev_err(dev, "Failed to init device\n");
		goto err_init_dev;
	}

	ret = ntb_register_device(&ndev->ntb);
	if (ret) {
		dev_err(dev, "Failed to register NTB device\n");
		goto err_register_dev;
	}

	return 0;

err_register_dev:
	ntb_epf_cleanup_isr(ndev);

err_init_dev:
	ntb_epf_deinit_pci(ndev);

	return ret;
}

static void ntb_epf_pci_remove(struct pci_dev *pdev)
{
	struct ntb_epf_dev *ndev = pci_get_drvdata(pdev);

	ntb_unregister_device(&ndev->ntb);
	ntb_epf_cleanup_isr(ndev);
	ntb_epf_deinit_pci(ndev);
}

static const struct ntb_epf_data j721e_data = {
	.ctrl_reg_bar = BAR_0,
	.peer_spad_reg_bar = BAR_1,
	.db_reg_bar = BAR_2,
};

static const struct pci_device_id ntb_epf_pci_tbl[] = {
	{
		PCI_DEVICE(PCI_VENDOR_ID_TI, PCI_DEVICE_ID_TI_J721E),
		.class = PCI_CLASS_MEMORY_RAM << 8, .class_mask = 0xffff00,
		.driver_data = (kernel_ulong_t)&j721e_data,
	},
	{ },
};

static struct pci_driver ntb_epf_pci_driver = {
	.name		= KBUILD_MODNAME,
	.id_table	= ntb_epf_pci_tbl,
	.probe		= ntb_epf_pci_probe,
	.remove		= ntb_epf_pci_remove,
};
module_pci_driver(ntb_epf_pci_driver);

MODULE_DESCRIPTION("PCI ENDPOINT NTB HOST DRIVER");
MODULE_AUTHOR("Kishon Vijay Abraham I <kishon@ti.com>");
MODULE_LICENSE("GPL v2");