/*
 *  pci-rcar-gen2: internal PCI bus support
 *
 * Copyright (C) 2013 Renesas Solutions Corp.
 * Copyright (C) 2013 Cogent Embedded, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/delay.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>

/* AHB-PCI Bridge PCI communication registers */
#define RCAR_AHBPCI_PCICOM_OFFSET	0x800

#define RCAR_PCIAHB_WIN1_CTR_REG	(RCAR_AHBPCI_PCICOM_OFFSET + 0x00)
#define RCAR_PCIAHB_WIN2_CTR_REG	(RCAR_AHBPCI_PCICOM_OFFSET + 0x04)
#define RCAR_PCIAHB_PREFETCH0		0x0
#define RCAR_PCIAHB_PREFETCH4		0x1
#define RCAR_PCIAHB_PREFETCH8		0x2
#define RCAR_PCIAHB_PREFETCH16		0x3

#define RCAR_AHBPCI_WIN1_CTR_REG	(RCAR_AHBPCI_PCICOM_OFFSET + 0x10)
#define RCAR_AHBPCI_WIN2_CTR_REG	(RCAR_AHBPCI_PCICOM_OFFSET + 0x14)
#define RCAR_AHBPCI_WIN_CTR_MEM		(3 << 1)
#define RCAR_AHBPCI_WIN_CTR_CFG		(5 << 1)
#define RCAR_AHBPCI_WIN1_HOST		(1 << 30)
#define RCAR_AHBPCI_WIN1_DEVICE		(1 << 31)

#define RCAR_PCI_INT_ENABLE_REG		(RCAR_AHBPCI_PCICOM_OFFSET + 0x20)
#define RCAR_PCI_INT_STATUS_REG		(RCAR_AHBPCI_PCICOM_OFFSET + 0x24)
#define RCAR_PCI_INT_A			(1 << 16)
#define RCAR_PCI_INT_B			(1 << 17)
#define RCAR_PCI_INT_PME		(1 << 19)

#define RCAR_AHB_BUS_CTR_REG		(RCAR_AHBPCI_PCICOM_OFFSET + 0x30)
#define RCAR_AHB_BUS_MMODE_HTRANS	(1 << 0)
#define RCAR_AHB_BUS_MMODE_BYTE_BURST	(1 << 1)
#define RCAR_AHB_BUS_MMODE_WR_INCR	(1 << 2)
#define RCAR_AHB_BUS_MMODE_HBUS_REQ	(1 << 7)
#define RCAR_AHB_BUS_SMODE_READYCTR	(1 << 17)
#define RCAR_AHB_BUS_MODE		(RCAR_AHB_BUS_MMODE_HTRANS |	\
					RCAR_AHB_BUS_MMODE_BYTE_BURST |	\
					RCAR_AHB_BUS_MMODE_WR_INCR |	\
					RCAR_AHB_BUS_MMODE_HBUS_REQ |	\
					RCAR_AHB_BUS_SMODE_READYCTR)

#define RCAR_USBCTR_REG			(RCAR_AHBPCI_PCICOM_OFFSET + 0x34)
#define RCAR_USBCTR_USBH_RST		(1 << 0)
#define RCAR_USBCTR_PCICLK_MASK		(1 << 1)
#define RCAR_USBCTR_PLL_RST		(1 << 2)
#define RCAR_USBCTR_DIRPD		(1 << 8)
#define RCAR_USBCTR_PCIAHB_WIN2_EN	(1 << 9)
#define RCAR_USBCTR_PCIAHB_WIN1_256M	(0 << 10)
#define RCAR_USBCTR_PCIAHB_WIN1_512M	(1 << 10)
#define RCAR_USBCTR_PCIAHB_WIN1_1G	(2 << 10)
#define RCAR_USBCTR_PCIAHB_WIN1_2G	(3 << 10)
#define RCAR_USBCTR_PCIAHB_WIN1_MASK	(3 << 10)

#define RCAR_PCI_ARBITER_CTR_REG	(RCAR_AHBPCI_PCICOM_OFFSET + 0x40)
#define RCAR_PCI_ARBITER_PCIREQ0	(1 << 0)
#define RCAR_PCI_ARBITER_PCIREQ1	(1 << 1)
#define RCAR_PCI_ARBITER_PCIBP_MODE	(1 << 12)

#define RCAR_PCI_UNIT_REV_REG		(RCAR_AHBPCI_PCICOM_OFFSET + 0x48)

/* Number of internal PCI controllers */
#define RCAR_PCI_NR_CONTROLLERS		3

struct rcar_pci_priv {
	struct device *dev;
	void __iomem *reg;
	struct resource io_res;
	struct resource mem_res;
	struct resource *cfg_res;
	int irq;
};

/* PCI configuration space operations */
static void __iomem *rcar_pci_cfg_base(struct pci_bus *bus, unsigned int devfn,
				       int where)
{
	struct pci_sys_data *sys = bus->sysdata;
	struct rcar_pci_priv *priv = sys->private_data;
	int slot, val;

	if (sys->busnr != bus->number || PCI_FUNC(devfn))
		return NULL;

	/* Only one EHCI/OHCI device built-in */
	slot = PCI_SLOT(devfn);
	if (slot > 2)
		return NULL;

	val = slot ? RCAR_AHBPCI_WIN1_DEVICE | RCAR_AHBPCI_WIN_CTR_CFG :
		     RCAR_AHBPCI_WIN1_HOST | RCAR_AHBPCI_WIN_CTR_CFG;

	iowrite32(val, priv->reg + RCAR_AHBPCI_WIN1_CTR_REG);
	return priv->reg + (slot >> 1) * 0x100 + where;
}

static int rcar_pci_read_config(struct pci_bus *bus, unsigned int devfn,
				int where, int size, u32 *val)
{
	void __iomem *reg = rcar_pci_cfg_base(bus, devfn, where);

	if (!reg)
		return PCIBIOS_DEVICE_NOT_FOUND;

	switch (size) {
	case 1:
		*val = ioread8(reg);
		break;
	case 2:
		*val = ioread16(reg);
		break;
	default:
		*val = ioread32(reg);
		break;
	}

	return PCIBIOS_SUCCESSFUL;
}

static int rcar_pci_write_config(struct pci_bus *bus, unsigned int devfn,
				 int where, int size, u32 val)
{
	void __iomem *reg = rcar_pci_cfg_base(bus, devfn, where);

	if (!reg)
		return PCIBIOS_DEVICE_NOT_FOUND;

	switch (size) {
	case 1:
		iowrite8(val, reg);
		break;
	case 2:
		iowrite16(val, reg);
		break;
	default:
		iowrite32(val, reg);
		break;
	}

	return PCIBIOS_SUCCESSFUL;
}

/* PCI interrupt mapping */
static int __init rcar_pci_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
{
	struct pci_sys_data *sys = dev->bus->sysdata;
	struct rcar_pci_priv *priv = sys->private_data;

	return priv->irq;
}

/* PCI host controller setup */
static int __init rcar_pci_setup(int nr, struct pci_sys_data *sys)
{
	struct rcar_pci_priv *priv = sys->private_data;
	void __iomem *reg = priv->reg;
	u32 val;

	pm_runtime_enable(priv->dev);
	pm_runtime_get_sync(priv->dev);

	val = ioread32(reg + RCAR_PCI_UNIT_REV_REG);
	dev_info(priv->dev, "PCI: bus%u revision %x\n", sys->busnr, val);

	/* Disable Direct Power Down State and assert reset */
	val = ioread32(reg + RCAR_USBCTR_REG) & ~RCAR_USBCTR_DIRPD;
	val |= RCAR_USBCTR_USBH_RST | RCAR_USBCTR_PLL_RST;
	iowrite32(val, reg + RCAR_USBCTR_REG);
	udelay(4);

	/* De-assert reset and set PCIAHB window1 size to 1GB */
	val &= ~(RCAR_USBCTR_PCIAHB_WIN1_MASK | RCAR_USBCTR_PCICLK_MASK |
		 RCAR_USBCTR_USBH_RST | RCAR_USBCTR_PLL_RST);
	iowrite32(val | RCAR_USBCTR_PCIAHB_WIN1_1G, reg + RCAR_USBCTR_REG);

	/* Configure AHB master and slave modes */
	iowrite32(RCAR_AHB_BUS_MODE, reg + RCAR_AHB_BUS_CTR_REG);

	/* Configure PCI arbiter */
	val = ioread32(reg + RCAR_PCI_ARBITER_CTR_REG);
	val |= RCAR_PCI_ARBITER_PCIREQ0 | RCAR_PCI_ARBITER_PCIREQ1 |
	       RCAR_PCI_ARBITER_PCIBP_MODE;
	iowrite32(val, reg + RCAR_PCI_ARBITER_CTR_REG);

	/* PCI-AHB mapping: 0x40000000-0x80000000 */
	iowrite32(0x40000000 | RCAR_PCIAHB_PREFETCH16,
		  reg + RCAR_PCIAHB_WIN1_CTR_REG);

	/* AHB-PCI mapping: OHCI/EHCI registers */
	val = priv->mem_res.start | RCAR_AHBPCI_WIN_CTR_MEM;
	iowrite32(val, reg + RCAR_AHBPCI_WIN2_CTR_REG);

	/* Enable AHB-PCI bridge PCI configuration access */
	iowrite32(RCAR_AHBPCI_WIN1_HOST | RCAR_AHBPCI_WIN_CTR_CFG,
		  reg + RCAR_AHBPCI_WIN1_CTR_REG);
	/* Set PCI-AHB Window1 address */
	iowrite32(0x40000000 | PCI_BASE_ADDRESS_MEM_PREFETCH,
		  reg + PCI_BASE_ADDRESS_1);
	/* Set AHB-PCI bridge PCI communication area address */
	val = priv->cfg_res->start + RCAR_AHBPCI_PCICOM_OFFSET;
	iowrite32(val, reg + PCI_BASE_ADDRESS_0);

	val = ioread32(reg + PCI_COMMAND);
	val |= PCI_COMMAND_SERR | PCI_COMMAND_PARITY |
	       PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER;
	iowrite32(val, reg + PCI_COMMAND);

	/* Enable PCI interrupts */
	iowrite32(RCAR_PCI_INT_A | RCAR_PCI_INT_B | RCAR_PCI_INT_PME,
		  reg + RCAR_PCI_INT_ENABLE_REG);

	/* Add PCI resources */
	pci_add_resource(&sys->resources, &priv->io_res);
	pci_add_resource(&sys->resources, &priv->mem_res);

	return 1;
}

static struct pci_ops rcar_pci_ops = {
	.read	= rcar_pci_read_config,
	.write	= rcar_pci_write_config,
};

static struct hw_pci rcar_hw_pci __initdata = {
	.map_irq	= rcar_pci_map_irq,
	.ops		= &rcar_pci_ops,
	.setup		= rcar_pci_setup,
};

static int rcar_pci_count __initdata;

static int __init rcar_pci_add_controller(struct rcar_pci_priv *priv)
{
	void **private_data;
	int count;

	if (rcar_hw_pci.nr_controllers < rcar_pci_count)
		goto add_priv;

	/* (Re)allocate private data pointer array if needed */
	count = rcar_pci_count + RCAR_PCI_NR_CONTROLLERS;
	private_data = kzalloc(count * sizeof(void *), GFP_KERNEL);
	if (!private_data)
		return -ENOMEM;

	rcar_pci_count = count;
	if (rcar_hw_pci.private_data) {
		memcpy(private_data, rcar_hw_pci.private_data,
		       rcar_hw_pci.nr_controllers * sizeof(void *));
		kfree(rcar_hw_pci.private_data);
	}

	rcar_hw_pci.private_data = private_data;

add_priv:
	/* Add private data pointer to the array */
	rcar_hw_pci.private_data[rcar_hw_pci.nr_controllers++] = priv;
	return 0;
}

static int __init rcar_pci_probe(struct platform_device *pdev)
{
	struct resource *cfg_res, *mem_res;
	struct rcar_pci_priv *priv;
	void __iomem *reg;

	cfg_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	reg = devm_ioremap_resource(&pdev->dev, cfg_res);
	if (IS_ERR(reg))
		return PTR_ERR(reg);

	mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
	if (!mem_res || !mem_res->start)
		return -ENODEV;

	priv = devm_kzalloc(&pdev->dev,
			    sizeof(struct rcar_pci_priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	priv->mem_res = *mem_res;
	/*
	 * The controller does not support/use port I/O,
	 * so setup a dummy port I/O region here.
	 */
	priv->io_res.start = priv->mem_res.start;
	priv->io_res.end = priv->mem_res.end;
	priv->io_res.flags = IORESOURCE_IO;

	priv->cfg_res = cfg_res;

	priv->irq = platform_get_irq(pdev, 0);
	priv->reg = reg;
	priv->dev = &pdev->dev;

	return rcar_pci_add_controller(priv);
}

static struct platform_driver rcar_pci_driver = {
	.driver = {
		.name = "pci-rcar-gen2",
	},
};

static int __init rcar_pci_init(void)
{
	int retval;

	retval = platform_driver_probe(&rcar_pci_driver, rcar_pci_probe);
	if (!retval)
		pci_common_init(&rcar_hw_pci);

	/* Private data pointer array is not needed any more */
	kfree(rcar_hw_pci.private_data);
	rcar_hw_pci.private_data = NULL;

	return retval;
}

subsys_initcall(rcar_pci_init);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Renesas R-Car Gen2 internal PCI");
MODULE_AUTHOR("Valentine Barshak <valentine.barshak@cogentembedded.com>");