/*
 * Support for Faraday Technology FTPC100 PCI Controller
 *
 * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
 *
 * Based on the out-of-tree OpenWRT patch for Cortina Gemini:
 * Copyright (C) 2009 Janos Laube <janos.dev@gmail.com>
 * Copyright (C) 2009 Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
 * Based on SL2312 PCI controller code
 * Storlink (C) 2003
 */

#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/of_irq.h>
#include <linux/of_pci.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/irqdomain.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/bitops.h>
#include <linux/irq.h>

/*
 * Special configuration registers directly in the first few words
 * in I/O space.
 */
#define PCI_IOSIZE	0x00
#define PCI_PROT	0x04 /* AHB protection */
#define PCI_CTRL	0x08 /* PCI control signal */
#define PCI_SOFTRST	0x10 /* Soft reset counter and response error enable */
#define PCI_CONFIG	0x28 /* PCI configuration command register */
#define PCI_DATA	0x2C

#define FARADAY_PCI_PMC			0x40 /* Power management control */
#define FARADAY_PCI_PMCSR		0x44 /* Power management status */
#define FARADAY_PCI_CTRL1		0x48 /* Control register 1 */
#define FARADAY_PCI_CTRL2		0x4C /* Control register 2 */
#define FARADAY_PCI_MEM1_BASE_SIZE	0x50 /* Memory base and size #1 */
#define FARADAY_PCI_MEM2_BASE_SIZE	0x54 /* Memory base and size #2 */
#define FARADAY_PCI_MEM3_BASE_SIZE	0x58 /* Memory base and size #3 */

/* Bits 31..28 gives INTD..INTA status */
#define PCI_CTRL2_INTSTS_SHIFT		28
#define PCI_CTRL2_INTMASK_CMDERR	BIT(27)
#define PCI_CTRL2_INTMASK_PARERR	BIT(26)
/* Bits 25..22 masks INTD..INTA */
#define PCI_CTRL2_INTMASK_SHIFT		22
#define PCI_CTRL2_INTMASK_MABRT_RX	BIT(21)
#define PCI_CTRL2_INTMASK_TABRT_RX	BIT(20)
#define PCI_CTRL2_INTMASK_TABRT_TX	BIT(19)
#define PCI_CTRL2_INTMASK_RETRY4	BIT(18)
#define PCI_CTRL2_INTMASK_SERR_RX	BIT(17)
#define PCI_CTRL2_INTMASK_PERR_RX	BIT(16)
/* Bit 15 reserved */
#define PCI_CTRL2_MSTPRI_REQ6		BIT(14)
#define PCI_CTRL2_MSTPRI_REQ5		BIT(13)
#define PCI_CTRL2_MSTPRI_REQ4		BIT(12)
#define PCI_CTRL2_MSTPRI_REQ3		BIT(11)
#define PCI_CTRL2_MSTPRI_REQ2		BIT(10)
#define PCI_CTRL2_MSTPRI_REQ1		BIT(9)
#define PCI_CTRL2_MSTPRI_REQ0		BIT(8)
/* Bits 7..4 reserved */
/* Bits 3..0 TRDYW */

/*
 * Memory configs:
 * Bit 31..20 defines the PCI side memory base
 * Bit 19..16 (4 bits) defines the size per below
 */
#define FARADAY_PCI_MEMBASE_MASK	0xfff00000
#define FARADAY_PCI_MEMSIZE_1MB		0x0
#define FARADAY_PCI_MEMSIZE_2MB		0x1
#define FARADAY_PCI_MEMSIZE_4MB		0x2
#define FARADAY_PCI_MEMSIZE_8MB		0x3
#define FARADAY_PCI_MEMSIZE_16MB	0x4
#define FARADAY_PCI_MEMSIZE_32MB	0x5
#define FARADAY_PCI_MEMSIZE_64MB	0x6
#define FARADAY_PCI_MEMSIZE_128MB	0x7
#define FARADAY_PCI_MEMSIZE_256MB	0x8
#define FARADAY_PCI_MEMSIZE_512MB	0x9
#define FARADAY_PCI_MEMSIZE_1GB		0xa
#define FARADAY_PCI_MEMSIZE_2GB		0xb
#define FARADAY_PCI_MEMSIZE_SHIFT	16

/*
 * The DMA base is set to 0x0 for all memory segments, it reflects the
 * fact that the memory of the host system starts at 0x0.
 */
#define FARADAY_PCI_DMA_MEM1_BASE	0x00000000
#define FARADAY_PCI_DMA_MEM2_BASE	0x00000000
#define FARADAY_PCI_DMA_MEM3_BASE	0x00000000

/* Defines for PCI configuration command register */
#define PCI_CONF_ENABLE		BIT(31)
#define PCI_CONF_WHERE(r)	((r) & 0xFC)
#define PCI_CONF_BUS(b)		(((b) & 0xFF) << 16)
#define PCI_CONF_DEVICE(d)	(((d) & 0x1F) << 11)
#define PCI_CONF_FUNCTION(f)	(((f) & 0x07) << 8)

/**
 * struct faraday_pci_variant - encodes IP block differences
 * @cascaded_irq: this host has cascaded IRQs from an interrupt controller
 *	embedded in the host bridge.
 */
struct faraday_pci_variant {
	bool cascaded_irq;
};

struct faraday_pci {
	struct device *dev;
	void __iomem *base;
	struct irq_domain *irqdomain;
	struct pci_bus *bus;
};

static int faraday_res_to_memcfg(resource_size_t mem_base,
				 resource_size_t mem_size, u32 *val)
{
	u32 outval;

	switch (mem_size) {
	case SZ_1M:
		outval = FARADAY_PCI_MEMSIZE_1MB;
		break;
	case SZ_2M:
		outval = FARADAY_PCI_MEMSIZE_2MB;
		break;
	case SZ_4M:
		outval = FARADAY_PCI_MEMSIZE_4MB;
		break;
	case SZ_8M:
		outval = FARADAY_PCI_MEMSIZE_8MB;
		break;
	case SZ_16M:
		outval = FARADAY_PCI_MEMSIZE_16MB;
		break;
	case SZ_32M:
		outval = FARADAY_PCI_MEMSIZE_32MB;
		break;
	case SZ_64M:
		outval = FARADAY_PCI_MEMSIZE_64MB;
		break;
	case SZ_128M:
		outval = FARADAY_PCI_MEMSIZE_128MB;
		break;
	case SZ_256M:
		outval = FARADAY_PCI_MEMSIZE_256MB;
		break;
	case SZ_512M:
		outval = FARADAY_PCI_MEMSIZE_512MB;
		break;
	case SZ_1G:
		outval = FARADAY_PCI_MEMSIZE_1GB;
		break;
	case SZ_2G:
		outval = FARADAY_PCI_MEMSIZE_2GB;
		break;
	default:
		return -EINVAL;
	}
	outval <<= FARADAY_PCI_MEMSIZE_SHIFT;

	/* This is probably not good */
	if (mem_base & ~(FARADAY_PCI_MEMBASE_MASK))
		pr_warn("truncated PCI memory base\n");
	/* Translate to bridge side address space */
	outval |= (mem_base & FARADAY_PCI_MEMBASE_MASK);
	pr_debug("Translated pci base @%pap, size %pap to config %08x\n",
		 &mem_base, &mem_size, outval);

	*val = outval;
	return 0;
}

static int faraday_raw_pci_read_config(struct faraday_pci *p, int bus_number,
				       unsigned int fn, int config, int size,
				       u32 *value)
{
	writel(PCI_CONF_BUS(bus_number) |
			PCI_CONF_DEVICE(PCI_SLOT(fn)) |
			PCI_CONF_FUNCTION(PCI_FUNC(fn)) |
			PCI_CONF_WHERE(config) |
			PCI_CONF_ENABLE,
			p->base + PCI_CONFIG);

	*value = readl(p->base + PCI_DATA);

	if (size == 1)
		*value = (*value >> (8 * (config & 3))) & 0xFF;
	else if (size == 2)
		*value = (*value >> (8 * (config & 3))) & 0xFFFF;

	return PCIBIOS_SUCCESSFUL;
}

static int faraday_pci_read_config(struct pci_bus *bus, unsigned int fn,
				   int config, int size, u32 *value)
{
	struct faraday_pci *p = bus->sysdata;

	dev_dbg(&bus->dev,
		"[read]  slt: %.2d, fnc: %d, cnf: 0x%.2X, val (%d bytes): 0x%.8X\n",
		PCI_SLOT(fn), PCI_FUNC(fn), config, size, *value);

	return faraday_raw_pci_read_config(p, bus->number, fn, config, size, value);
}

static int faraday_raw_pci_write_config(struct faraday_pci *p, int bus_number,
					 unsigned int fn, int config, int size,
					 u32 value)
{
	int ret = PCIBIOS_SUCCESSFUL;

	writel(PCI_CONF_BUS(bus_number) |
			PCI_CONF_DEVICE(PCI_SLOT(fn)) |
			PCI_CONF_FUNCTION(PCI_FUNC(fn)) |
			PCI_CONF_WHERE(config) |
			PCI_CONF_ENABLE,
			p->base + PCI_CONFIG);

	switch (size) {
	case 4:
		writel(value, p->base + PCI_DATA);
		break;
	case 2:
		writew(value, p->base + PCI_DATA + (config & 3));
		break;
	case 1:
		writeb(value, p->base + PCI_DATA + (config & 3));
		break;
	default:
		ret = PCIBIOS_BAD_REGISTER_NUMBER;
	}

	return ret;
}

static int faraday_pci_write_config(struct pci_bus *bus, unsigned int fn,
				    int config, int size, u32 value)
{
	struct faraday_pci *p = bus->sysdata;

	dev_dbg(&bus->dev,
		"[write] slt: %.2d, fnc: %d, cnf: 0x%.2X, val (%d bytes): 0x%.8X\n",
		PCI_SLOT(fn), PCI_FUNC(fn), config, size, value);

	return faraday_raw_pci_write_config(p, bus->number, fn, config, size,
					    value);
}

static struct pci_ops faraday_pci_ops = {
	.read	= faraday_pci_read_config,
	.write	= faraday_pci_write_config,
};

static void faraday_pci_ack_irq(struct irq_data *d)
{
	struct faraday_pci *p = irq_data_get_irq_chip_data(d);
	unsigned int reg;

	faraday_raw_pci_read_config(p, 0, 0, FARADAY_PCI_CTRL2, 4, &reg);
	reg &= ~(0xF << PCI_CTRL2_INTSTS_SHIFT);
	reg |= BIT(irqd_to_hwirq(d) + PCI_CTRL2_INTSTS_SHIFT);
	faraday_raw_pci_write_config(p, 0, 0, FARADAY_PCI_CTRL2, 4, reg);
}

static void faraday_pci_mask_irq(struct irq_data *d)
{
	struct faraday_pci *p = irq_data_get_irq_chip_data(d);
	unsigned int reg;

	faraday_raw_pci_read_config(p, 0, 0, FARADAY_PCI_CTRL2, 4, &reg);
	reg &= ~((0xF << PCI_CTRL2_INTSTS_SHIFT)
		 | BIT(irqd_to_hwirq(d) + PCI_CTRL2_INTMASK_SHIFT));
	faraday_raw_pci_write_config(p, 0, 0, FARADAY_PCI_CTRL2, 4, reg);
}

static void faraday_pci_unmask_irq(struct irq_data *d)
{
	struct faraday_pci *p = irq_data_get_irq_chip_data(d);
	unsigned int reg;

	faraday_raw_pci_read_config(p, 0, 0, FARADAY_PCI_CTRL2, 4, &reg);
	reg &= ~(0xF << PCI_CTRL2_INTSTS_SHIFT);
	reg |= BIT(irqd_to_hwirq(d) + PCI_CTRL2_INTMASK_SHIFT);
	faraday_raw_pci_write_config(p, 0, 0, FARADAY_PCI_CTRL2, 4, reg);
}

static void faraday_pci_irq_handler(struct irq_desc *desc)
{
	struct faraday_pci *p = irq_desc_get_handler_data(desc);
	struct irq_chip *irqchip = irq_desc_get_chip(desc);
	unsigned int irq_stat, reg, i;

	faraday_raw_pci_read_config(p, 0, 0, FARADAY_PCI_CTRL2, 4, &reg);
	irq_stat = reg >> PCI_CTRL2_INTSTS_SHIFT;

	chained_irq_enter(irqchip, desc);

	for (i = 0; i < 4; i++) {
		if ((irq_stat & BIT(i)) == 0)
			continue;
		generic_handle_irq(irq_find_mapping(p->irqdomain, i));
	}

	chained_irq_exit(irqchip, desc);
}

static struct irq_chip faraday_pci_irq_chip = {
	.name = "PCI",
	.irq_ack = faraday_pci_ack_irq,
	.irq_mask = faraday_pci_mask_irq,
	.irq_unmask = faraday_pci_unmask_irq,
};

static int faraday_pci_irq_map(struct irq_domain *domain, unsigned int irq,
			       irq_hw_number_t hwirq)
{
	irq_set_chip_and_handler(irq, &faraday_pci_irq_chip, handle_level_irq);
	irq_set_chip_data(irq, domain->host_data);

	return 0;
}

static const struct irq_domain_ops faraday_pci_irqdomain_ops = {
	.map = faraday_pci_irq_map,
};

static int faraday_pci_setup_cascaded_irq(struct faraday_pci *p)
{
	struct device_node *intc = of_get_next_child(p->dev->of_node, NULL);
	int irq;
	int i;

	if (!intc) {
		dev_err(p->dev, "missing child interrupt-controller node\n");
		return -EINVAL;
	}

	/* All PCI IRQs cascade off this one */
	irq = of_irq_get(intc, 0);
	if (!irq) {
		dev_err(p->dev, "failed to get parent IRQ\n");
		return -EINVAL;
	}

	p->irqdomain = irq_domain_add_linear(intc, 4,
					     &faraday_pci_irqdomain_ops, p);
	if (!p->irqdomain) {
		dev_err(p->dev, "failed to create Gemini PCI IRQ domain\n");
		return -EINVAL;
	}

	irq_set_chained_handler_and_data(irq, faraday_pci_irq_handler, p);

	for (i = 0; i < 4; i++)
		irq_create_mapping(p->irqdomain, i);

	return 0;
}

static int pci_dma_range_parser_init(struct of_pci_range_parser *parser,
				     struct device_node *node)
{
	const int na = 3, ns = 2;
	int rlen;

	parser->node = node;
	parser->pna = of_n_addr_cells(node);
	parser->np = parser->pna + na + ns;

	parser->range = of_get_property(node, "dma-ranges", &rlen);
	if (!parser->range)
		return -ENOENT;
	parser->end = parser->range + rlen / sizeof(__be32);

	return 0;
}

static int faraday_pci_parse_map_dma_ranges(struct faraday_pci *p,
					    struct device_node *np)
{
	struct of_pci_range range;
	struct of_pci_range_parser parser;
	struct device *dev = p->dev;
	u32 confreg[3] = {
		FARADAY_PCI_MEM1_BASE_SIZE,
		FARADAY_PCI_MEM2_BASE_SIZE,
		FARADAY_PCI_MEM3_BASE_SIZE,
	};
	int i = 0;
	u32 val;

	if (pci_dma_range_parser_init(&parser, np)) {
		dev_err(dev, "missing dma-ranges property\n");
		return -EINVAL;
	}

	/*
	 * Get the dma-ranges from the device tree
	 */
	for_each_of_pci_range(&parser, &range) {
		u64 end = range.pci_addr + range.size - 1;
		int ret;

		ret = faraday_res_to_memcfg(range.pci_addr, range.size, &val);
		if (ret) {
			dev_err(dev,
				"DMA range %d: illegal MEM resource size\n", i);
			return -EINVAL;
		}

		dev_info(dev, "DMA MEM%d BASE: 0x%016llx -> 0x%016llx config %08x\n",
			 i + 1, range.pci_addr, end, val);
		if (i <= 2) {
			faraday_raw_pci_write_config(p, 0, 0, confreg[i],
						     4, val);
		} else {
			dev_err(dev, "ignore extraneous dma-range %d\n", i);
			break;
		}

		i++;
	}

	return 0;
}

static int faraday_pci_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	const struct faraday_pci_variant *variant =
		of_device_get_match_data(dev);
	struct resource *regs;
	resource_size_t io_base;
	struct resource_entry *win;
	struct faraday_pci *p;
	struct resource *mem;
	struct resource *io;
	struct pci_host_bridge *host;
	int ret;
	u32 val;
	LIST_HEAD(res);

	host = pci_alloc_host_bridge(sizeof(*p));
	if (!host)
		return -ENOMEM;

	host->dev.parent = dev;
	host->ops = &faraday_pci_ops;
	host->busnr = 0;
	host->msi = NULL;
	p = pci_host_bridge_priv(host);
	host->sysdata = p;
	p->dev = dev;

	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	p->base = devm_ioremap_resource(dev, regs);
	if (IS_ERR(p->base))
		return PTR_ERR(p->base);

	ret = of_pci_get_host_bridge_resources(dev->of_node, 0, 0xff,
					       &res, &io_base);
	if (ret)
		return ret;

	ret = devm_request_pci_bus_resources(dev, &res);
	if (ret)
		return ret;

	/* Get the I/O and memory ranges from DT */
	resource_list_for_each_entry(win, &res) {
		switch (resource_type(win->res)) {
		case IORESOURCE_IO:
			io = win->res;
			io->name = "Gemini PCI I/O";
			if (!faraday_res_to_memcfg(io->start - win->offset,
						   resource_size(io), &val)) {
				/* setup I/O space size */
				writel(val, p->base + PCI_IOSIZE);
			} else {
				dev_err(dev, "illegal IO mem size\n");
				return -EINVAL;
			}
			ret = pci_remap_iospace(io, io_base);
			if (ret) {
				dev_warn(dev, "error %d: failed to map resource %pR\n",
					 ret, io);
				continue;
			}
			break;
		case IORESOURCE_MEM:
			mem = win->res;
			mem->name = "Gemini PCI MEM";
			break;
		case IORESOURCE_BUS:
			break;
		default:
			break;
		}
	}

	/* Setup hostbridge */
	val = readl(p->base + PCI_CTRL);
	val |= PCI_COMMAND_IO;
	val |= PCI_COMMAND_MEMORY;
	val |= PCI_COMMAND_MASTER;
	writel(val, p->base + PCI_CTRL);
	/* Mask and clear all interrupts */
	faraday_raw_pci_write_config(p, 0, 0, FARADAY_PCI_CTRL2 + 2, 2, 0xF000);
	if (variant->cascaded_irq) {
		ret = faraday_pci_setup_cascaded_irq(p);
		if (ret) {
			dev_err(dev, "failed to setup cascaded IRQ\n");
			return ret;
		}
	}

	ret = faraday_pci_parse_map_dma_ranges(p, dev->of_node);
	if (ret)
		return ret;

	list_splice_init(&res, &host->windows);
	ret = pci_register_host_bridge(host);
	if (ret) {
		dev_err(dev, "failed to register host: %d\n", ret);
		return ret;
	}
	p->bus = host->bus;

	pci_scan_child_bus(p->bus);
	pci_fixup_irqs(pci_common_swizzle, of_irq_parse_and_map_pci);
	pci_bus_assign_resources(p->bus);
	pci_bus_add_devices(p->bus);
	pci_free_resource_list(&res);

	return 0;
}

/*
 * We encode bridge variants here, we have at least two so it doesn't
 * hurt to have infrastructure to encompass future variants as well.
 */
const struct faraday_pci_variant faraday_regular = {
	.cascaded_irq = true,
};

const struct faraday_pci_variant faraday_dual = {
	.cascaded_irq = false,
};

static const struct of_device_id faraday_pci_of_match[] = {
	{
		.compatible = "faraday,ftpci100",
		.data = &faraday_regular,
	},
	{
		.compatible = "faraday,ftpci100-dual",
		.data = &faraday_dual,
	},
	{},
};

static struct platform_driver faraday_pci_driver = {
	.driver = {
		.name = "ftpci100",
		.of_match_table = of_match_ptr(faraday_pci_of_match),
		.suppress_bind_attrs = true,
	},
	.probe  = faraday_pci_probe,
};
builtin_platform_driver(faraday_pci_driver);