/*
 *  Atheros AR71xx PCI host controller driver
 *
 *  Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
 *  Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
 *
 *  Parts of this file are based on Atheros' 2.6.15 BSP
 *
 *  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/resource.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/pci.h>
#include <linux/pci_regs.h>
#include <linux/interrupt.h>

#include <asm/mach-ath79/ar71xx_regs.h>
#include <asm/mach-ath79/ath79.h>
#include <asm/mach-ath79/pci.h>

#define AR71XX_PCI_MEM_BASE	0x10000000
#define AR71XX_PCI_MEM_SIZE	0x07000000

#define AR71XX_PCI_WIN0_OFFS		0x10000000
#define AR71XX_PCI_WIN1_OFFS		0x11000000
#define AR71XX_PCI_WIN2_OFFS		0x12000000
#define AR71XX_PCI_WIN3_OFFS		0x13000000
#define AR71XX_PCI_WIN4_OFFS		0x14000000
#define AR71XX_PCI_WIN5_OFFS		0x15000000
#define AR71XX_PCI_WIN6_OFFS		0x16000000
#define AR71XX_PCI_WIN7_OFFS		0x07000000

#define AR71XX_PCI_CFG_BASE		\
	(AR71XX_PCI_MEM_BASE + AR71XX_PCI_WIN7_OFFS + 0x10000)
#define AR71XX_PCI_CFG_SIZE		0x100

#define AR71XX_PCI_REG_CRP_AD_CBE	0x00
#define AR71XX_PCI_REG_CRP_WRDATA	0x04
#define AR71XX_PCI_REG_CRP_RDDATA	0x08
#define AR71XX_PCI_REG_CFG_AD		0x0c
#define AR71XX_PCI_REG_CFG_CBE		0x10
#define AR71XX_PCI_REG_CFG_WRDATA	0x14
#define AR71XX_PCI_REG_CFG_RDDATA	0x18
#define AR71XX_PCI_REG_PCI_ERR		0x1c
#define AR71XX_PCI_REG_PCI_ERR_ADDR	0x20
#define AR71XX_PCI_REG_AHB_ERR		0x24
#define AR71XX_PCI_REG_AHB_ERR_ADDR	0x28

#define AR71XX_PCI_CRP_CMD_WRITE	0x00010000
#define AR71XX_PCI_CRP_CMD_READ		0x00000000
#define AR71XX_PCI_CFG_CMD_READ		0x0000000a
#define AR71XX_PCI_CFG_CMD_WRITE	0x0000000b

#define AR71XX_PCI_INT_CORE		BIT(4)
#define AR71XX_PCI_INT_DEV2		BIT(2)
#define AR71XX_PCI_INT_DEV1		BIT(1)
#define AR71XX_PCI_INT_DEV0		BIT(0)

#define AR71XX_PCI_IRQ_COUNT		5

static DEFINE_SPINLOCK(ar71xx_pci_lock);
static void __iomem *ar71xx_pcicfg_base;

/* Byte lane enable bits */
static const u8 ar71xx_pci_ble_table[4][4] = {
	{0x0, 0xf, 0xf, 0xf},
	{0xe, 0xd, 0xb, 0x7},
	{0xc, 0xf, 0x3, 0xf},
	{0xf, 0xf, 0xf, 0xf},
};

static const u32 ar71xx_pci_read_mask[8] = {
	0, 0xff, 0xffff, 0, 0xffffffff, 0, 0, 0
};

static inline u32 ar71xx_pci_get_ble(int where, int size, int local)
{
	u32 t;

	t = ar71xx_pci_ble_table[size & 3][where & 3];
	BUG_ON(t == 0xf);
	t <<= (local) ? 20 : 4;

	return t;
}

static inline u32 ar71xx_pci_bus_addr(struct pci_bus *bus, unsigned int devfn,
				      int where)
{
	u32 ret;

	if (!bus->number) {
		/* type 0 */
		ret = (1 << PCI_SLOT(devfn)) | (PCI_FUNC(devfn) << 8) |
		      (where & ~3);
	} else {
		/* type 1 */
		ret = (bus->number << 16) | (PCI_SLOT(devfn) << 11) |
		      (PCI_FUNC(devfn) << 8) | (where & ~3) | 1;
	}

	return ret;
}

static int ar71xx_pci_check_error(int quiet)
{
	void __iomem *base = ar71xx_pcicfg_base;
	u32 pci_err;
	u32 ahb_err;

	pci_err = __raw_readl(base + AR71XX_PCI_REG_PCI_ERR) & 3;
	if (pci_err) {
		if (!quiet) {
			u32 addr;

			addr = __raw_readl(base + AR71XX_PCI_REG_PCI_ERR_ADDR);
			pr_crit("ar71xx: %s bus error %d at addr 0x%x\n",
				"PCI", pci_err, addr);
		}

		/* clear PCI error status */
		__raw_writel(pci_err, base + AR71XX_PCI_REG_PCI_ERR);
	}

	ahb_err = __raw_readl(base + AR71XX_PCI_REG_AHB_ERR) & 1;
	if (ahb_err) {
		if (!quiet) {
			u32 addr;

			addr = __raw_readl(base + AR71XX_PCI_REG_AHB_ERR_ADDR);
			pr_crit("ar71xx: %s bus error %d at addr 0x%x\n",
				"AHB", ahb_err, addr);
		}

		/* clear AHB error status */
		__raw_writel(ahb_err, base + AR71XX_PCI_REG_AHB_ERR);
	}

	return !!(ahb_err | pci_err);
}

static inline void ar71xx_pci_local_write(int where, int size, u32 value)
{
	void __iomem *base = ar71xx_pcicfg_base;
	u32 ad_cbe;

	value = value << (8 * (where & 3));

	ad_cbe = AR71XX_PCI_CRP_CMD_WRITE | (where & ~3);
	ad_cbe |= ar71xx_pci_get_ble(where, size, 1);

	__raw_writel(ad_cbe, base + AR71XX_PCI_REG_CRP_AD_CBE);
	__raw_writel(value, base + AR71XX_PCI_REG_CRP_WRDATA);
}

static inline int ar71xx_pci_set_cfgaddr(struct pci_bus *bus,
					 unsigned int devfn,
					 int where, int size, u32 cmd)
{
	void __iomem *base = ar71xx_pcicfg_base;
	u32 addr;

	addr = ar71xx_pci_bus_addr(bus, devfn, where);

	__raw_writel(addr, base + AR71XX_PCI_REG_CFG_AD);
	__raw_writel(cmd | ar71xx_pci_get_ble(where, size, 0),
		     base + AR71XX_PCI_REG_CFG_CBE);

	return ar71xx_pci_check_error(1);
}

static int ar71xx_pci_read_config(struct pci_bus *bus, unsigned int devfn,
				  int where, int size, u32 *value)
{
	void __iomem *base = ar71xx_pcicfg_base;
	unsigned long flags;
	u32 data;
	int err;
	int ret;

	ret = PCIBIOS_SUCCESSFUL;
	data = ~0;

	spin_lock_irqsave(&ar71xx_pci_lock, flags);

	err = ar71xx_pci_set_cfgaddr(bus, devfn, where, size,
				     AR71XX_PCI_CFG_CMD_READ);
	if (err)
		ret = PCIBIOS_DEVICE_NOT_FOUND;
	else
		data = __raw_readl(base + AR71XX_PCI_REG_CFG_RDDATA);

	spin_unlock_irqrestore(&ar71xx_pci_lock, flags);

	*value = (data >> (8 * (where & 3))) & ar71xx_pci_read_mask[size & 7];

	return ret;
}

static int ar71xx_pci_write_config(struct pci_bus *bus, unsigned int devfn,
				   int where, int size, u32 value)
{
	void __iomem *base = ar71xx_pcicfg_base;
	unsigned long flags;
	int err;
	int ret;

	value = value << (8 * (where & 3));
	ret = PCIBIOS_SUCCESSFUL;

	spin_lock_irqsave(&ar71xx_pci_lock, flags);

	err = ar71xx_pci_set_cfgaddr(bus, devfn, where, size,
				     AR71XX_PCI_CFG_CMD_WRITE);
	if (err)
		ret = PCIBIOS_DEVICE_NOT_FOUND;
	else
		__raw_writel(value, base + AR71XX_PCI_REG_CFG_WRDATA);

	spin_unlock_irqrestore(&ar71xx_pci_lock, flags);

	return ret;
}

static struct pci_ops ar71xx_pci_ops = {
	.read	= ar71xx_pci_read_config,
	.write	= ar71xx_pci_write_config,
};

static struct resource ar71xx_pci_io_resource = {
	.name		= "PCI IO space",
	.start		= 0,
	.end		= 0,
	.flags		= IORESOURCE_IO,
};

static struct resource ar71xx_pci_mem_resource = {
	.name		= "PCI memory space",
	.start		= AR71XX_PCI_MEM_BASE,
	.end		= AR71XX_PCI_MEM_BASE + AR71XX_PCI_MEM_SIZE - 1,
	.flags		= IORESOURCE_MEM
};

static struct pci_controller ar71xx_pci_controller = {
	.pci_ops	= &ar71xx_pci_ops,
	.mem_resource	= &ar71xx_pci_mem_resource,
	.io_resource	= &ar71xx_pci_io_resource,
};

static void ar71xx_pci_irq_handler(unsigned int irq, struct irq_desc *desc)
{
	void __iomem *base = ath79_reset_base;
	u32 pending;

	pending = __raw_readl(base + AR71XX_RESET_REG_PCI_INT_STATUS) &
		  __raw_readl(base + AR71XX_RESET_REG_PCI_INT_ENABLE);

	if (pending & AR71XX_PCI_INT_DEV0)
		generic_handle_irq(ATH79_PCI_IRQ(0));

	else if (pending & AR71XX_PCI_INT_DEV1)
		generic_handle_irq(ATH79_PCI_IRQ(1));

	else if (pending & AR71XX_PCI_INT_DEV2)
		generic_handle_irq(ATH79_PCI_IRQ(2));

	else if (pending & AR71XX_PCI_INT_CORE)
		generic_handle_irq(ATH79_PCI_IRQ(4));

	else
		spurious_interrupt();
}

static void ar71xx_pci_irq_unmask(struct irq_data *d)
{
	unsigned int irq = d->irq - ATH79_PCI_IRQ_BASE;
	void __iomem *base = ath79_reset_base;
	u32 t;

	t = __raw_readl(base + AR71XX_RESET_REG_PCI_INT_ENABLE);
	__raw_writel(t | (1 << irq), base + AR71XX_RESET_REG_PCI_INT_ENABLE);

	/* flush write */
	__raw_readl(base + AR71XX_RESET_REG_PCI_INT_ENABLE);
}

static void ar71xx_pci_irq_mask(struct irq_data *d)
{
	unsigned int irq = d->irq - ATH79_PCI_IRQ_BASE;
	void __iomem *base = ath79_reset_base;
	u32 t;

	t = __raw_readl(base + AR71XX_RESET_REG_PCI_INT_ENABLE);
	__raw_writel(t & ~(1 << irq), base + AR71XX_RESET_REG_PCI_INT_ENABLE);

	/* flush write */
	__raw_readl(base + AR71XX_RESET_REG_PCI_INT_ENABLE);
}

static struct irq_chip ar71xx_pci_irq_chip = {
	.name		= "AR71XX PCI",
	.irq_mask	= ar71xx_pci_irq_mask,
	.irq_unmask	= ar71xx_pci_irq_unmask,
	.irq_mask_ack	= ar71xx_pci_irq_mask,
};

static __init void ar71xx_pci_irq_init(void)
{
	void __iomem *base = ath79_reset_base;
	int i;

	__raw_writel(0, base + AR71XX_RESET_REG_PCI_INT_ENABLE);
	__raw_writel(0, base + AR71XX_RESET_REG_PCI_INT_STATUS);

	BUILD_BUG_ON(ATH79_PCI_IRQ_COUNT < AR71XX_PCI_IRQ_COUNT);

	for (i = ATH79_PCI_IRQ_BASE;
	     i < ATH79_PCI_IRQ_BASE + AR71XX_PCI_IRQ_COUNT; i++)
		irq_set_chip_and_handler(i, &ar71xx_pci_irq_chip,
					 handle_level_irq);

	irq_set_chained_handler(ATH79_CPU_IRQ_IP2, ar71xx_pci_irq_handler);
}

static __init void ar71xx_pci_reset(void)
{
	void __iomem *ddr_base = ath79_ddr_base;

	ath79_device_reset_set(AR71XX_RESET_PCI_BUS | AR71XX_RESET_PCI_CORE);
	mdelay(100);

	ath79_device_reset_clear(AR71XX_RESET_PCI_BUS | AR71XX_RESET_PCI_CORE);
	mdelay(100);

	__raw_writel(AR71XX_PCI_WIN0_OFFS, ddr_base + AR71XX_DDR_REG_PCI_WIN0);
	__raw_writel(AR71XX_PCI_WIN1_OFFS, ddr_base + AR71XX_DDR_REG_PCI_WIN1);
	__raw_writel(AR71XX_PCI_WIN2_OFFS, ddr_base + AR71XX_DDR_REG_PCI_WIN2);
	__raw_writel(AR71XX_PCI_WIN3_OFFS, ddr_base + AR71XX_DDR_REG_PCI_WIN3);
	__raw_writel(AR71XX_PCI_WIN4_OFFS, ddr_base + AR71XX_DDR_REG_PCI_WIN4);
	__raw_writel(AR71XX_PCI_WIN5_OFFS, ddr_base + AR71XX_DDR_REG_PCI_WIN5);
	__raw_writel(AR71XX_PCI_WIN6_OFFS, ddr_base + AR71XX_DDR_REG_PCI_WIN6);
	__raw_writel(AR71XX_PCI_WIN7_OFFS, ddr_base + AR71XX_DDR_REG_PCI_WIN7);

	mdelay(100);
}

__init int ar71xx_pcibios_init(void)
{
	u32 t;

	ar71xx_pcicfg_base = ioremap(AR71XX_PCI_CFG_BASE, AR71XX_PCI_CFG_SIZE);
	if (ar71xx_pcicfg_base == NULL)
		return -ENOMEM;

	ar71xx_pci_reset();

	/* setup COMMAND register */
	t = PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER | PCI_COMMAND_INVALIDATE
	  | PCI_COMMAND_PARITY | PCI_COMMAND_SERR | PCI_COMMAND_FAST_BACK;
	ar71xx_pci_local_write(PCI_COMMAND, 4, t);

	/* clear bus errors */
	ar71xx_pci_check_error(1);

	ar71xx_pci_irq_init();

	register_pci_controller(&ar71xx_pci_controller);

	return 0;
}