/*
 * PCIe host controller driver for Marvell Armada-8K SoCs
 *
 * Armada-8K PCIe Glue Layer Source Code
 *
 * Copyright (C) 2016 Marvell Technology Group Ltd.
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/pci.h>
#include <linux/phy/phy.h>
#include <linux/platform_device.h>
#include <linux/resource.h>
#include <linux/of_pci.h>
#include <linux/of_irq.h>

#include "pcie-designware.h"

struct armada8k_pcie {
	void __iomem *base;
	struct clk *clk;
	struct pcie_port pp;
};

#define PCIE_VENDOR_REGS_OFFSET		0x8000

#define PCIE_GLOBAL_CONTROL_REG		0x0
#define PCIE_APP_LTSSM_EN		BIT(2)
#define PCIE_DEVICE_TYPE_SHIFT		4
#define PCIE_DEVICE_TYPE_MASK		0xF
#define PCIE_DEVICE_TYPE_RC		0x4 /* Root complex */

#define PCIE_GLOBAL_STATUS_REG		0x8
#define PCIE_GLB_STS_RDLH_LINK_UP	BIT(1)
#define PCIE_GLB_STS_PHY_LINK_UP	BIT(9)

#define PCIE_GLOBAL_INT_CAUSE1_REG	0x1C
#define PCIE_GLOBAL_INT_MASK1_REG	0x20
#define PCIE_INT_A_ASSERT_MASK		BIT(9)
#define PCIE_INT_B_ASSERT_MASK		BIT(10)
#define PCIE_INT_C_ASSERT_MASK		BIT(11)
#define PCIE_INT_D_ASSERT_MASK		BIT(12)

#define PCIE_ARCACHE_TRC_REG		0x50
#define PCIE_AWCACHE_TRC_REG		0x54
#define PCIE_ARUSER_REG			0x5C
#define PCIE_AWUSER_REG			0x60
/*
 * AR/AW Cache defauls: Normal memory, Write-Back, Read / Write
 * allocate
 */
#define ARCACHE_DEFAULT_VALUE		0x3511
#define AWCACHE_DEFAULT_VALUE		0x5311

#define DOMAIN_OUTER_SHAREABLE		0x2
#define AX_USER_DOMAIN_MASK		0x3
#define AX_USER_DOMAIN_SHIFT		4

#define to_armada8k_pcie(x)	container_of(x, struct armada8k_pcie, pp)

static int armada8k_pcie_link_up(struct pcie_port *pp)
{
	struct armada8k_pcie *pcie = to_armada8k_pcie(pp);
	u32 reg;
	u32 mask = PCIE_GLB_STS_RDLH_LINK_UP | PCIE_GLB_STS_PHY_LINK_UP;

	reg = readl(pcie->base + PCIE_GLOBAL_STATUS_REG);

	if ((reg & mask) == mask)
		return 1;

	dev_dbg(pp->dev, "No link detected (Global-Status: 0x%08x).\n", reg);
	return 0;
}

static void armada8k_pcie_establish_link(struct pcie_port *pp)
{
	struct armada8k_pcie *pcie = to_armada8k_pcie(pp);
	void __iomem *base = pcie->base;
	u32 reg;

	if (!dw_pcie_link_up(pp)) {
		/* Disable LTSSM state machine to enable configuration */
		reg = readl(base + PCIE_GLOBAL_CONTROL_REG);
		reg &= ~(PCIE_APP_LTSSM_EN);
		writel(reg, base + PCIE_GLOBAL_CONTROL_REG);
	}

	/* Set the device to root complex mode */
	reg = readl(base + PCIE_GLOBAL_CONTROL_REG);
	reg &= ~(PCIE_DEVICE_TYPE_MASK << PCIE_DEVICE_TYPE_SHIFT);
	reg |= PCIE_DEVICE_TYPE_RC << PCIE_DEVICE_TYPE_SHIFT;
	writel(reg, base + PCIE_GLOBAL_CONTROL_REG);

	/* Set the PCIe master AxCache attributes */
	writel(ARCACHE_DEFAULT_VALUE, base + PCIE_ARCACHE_TRC_REG);
	writel(AWCACHE_DEFAULT_VALUE, base + PCIE_AWCACHE_TRC_REG);

	/* Set the PCIe master AxDomain attributes */
	reg = readl(base + PCIE_ARUSER_REG);
	reg &= ~(AX_USER_DOMAIN_MASK << AX_USER_DOMAIN_SHIFT);
	reg |= DOMAIN_OUTER_SHAREABLE << AX_USER_DOMAIN_SHIFT;
	writel(reg, base + PCIE_ARUSER_REG);

	reg = readl(base + PCIE_AWUSER_REG);
	reg &= ~(AX_USER_DOMAIN_MASK << AX_USER_DOMAIN_SHIFT);
	reg |= DOMAIN_OUTER_SHAREABLE << AX_USER_DOMAIN_SHIFT;
	writel(reg, base + PCIE_AWUSER_REG);

	/* Enable INT A-D interrupts */
	reg = readl(base + PCIE_GLOBAL_INT_MASK1_REG);
	reg |= PCIE_INT_A_ASSERT_MASK | PCIE_INT_B_ASSERT_MASK |
	       PCIE_INT_C_ASSERT_MASK | PCIE_INT_D_ASSERT_MASK;
	writel(reg, base + PCIE_GLOBAL_INT_MASK1_REG);

	if (!dw_pcie_link_up(pp)) {
		/* Configuration done. Start LTSSM */
		reg = readl(base + PCIE_GLOBAL_CONTROL_REG);
		reg |= PCIE_APP_LTSSM_EN;
		writel(reg, base + PCIE_GLOBAL_CONTROL_REG);
	}

	/* Wait until the link becomes active again */
	if (dw_pcie_wait_for_link(pp))
		dev_err(pp->dev, "Link not up after reconfiguration\n");
}

static void armada8k_pcie_host_init(struct pcie_port *pp)
{
	dw_pcie_setup_rc(pp);
	armada8k_pcie_establish_link(pp);
}

static irqreturn_t armada8k_pcie_irq_handler(int irq, void *arg)
{
	struct pcie_port *pp = arg;
	struct armada8k_pcie *pcie = to_armada8k_pcie(pp);
	void __iomem *base = pcie->base;
	u32 val;

	/*
	 * Interrupts are directly handled by the device driver of the
	 * PCI device. However, they are also latched into the PCIe
	 * controller, so we simply discard them.
	 */
	val = readl(base + PCIE_GLOBAL_INT_CAUSE1_REG);
	writel(val, base + PCIE_GLOBAL_INT_CAUSE1_REG);

	return IRQ_HANDLED;
}

static struct pcie_host_ops armada8k_pcie_host_ops = {
	.link_up = armada8k_pcie_link_up,
	.host_init = armada8k_pcie_host_init,
};

static int armada8k_add_pcie_port(struct pcie_port *pp,
				  struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	int ret;

	pp->root_bus_nr = -1;
	pp->ops = &armada8k_pcie_host_ops;

	pp->irq = platform_get_irq(pdev, 0);
	if (!pp->irq) {
		dev_err(dev, "failed to get irq for port\n");
		return -ENODEV;
	}

	ret = devm_request_irq(dev, pp->irq, armada8k_pcie_irq_handler,
			       IRQF_SHARED, "armada8k-pcie", pp);
	if (ret) {
		dev_err(dev, "failed to request irq %d\n", pp->irq);
		return ret;
	}

	ret = dw_pcie_host_init(pp);
	if (ret) {
		dev_err(dev, "failed to initialize host: %d\n", ret);
		return ret;
	}

	return 0;
}

static int armada8k_pcie_probe(struct platform_device *pdev)
{
	struct armada8k_pcie *pcie;
	struct pcie_port *pp;
	struct device *dev = &pdev->dev;
	struct resource *base;
	int ret;

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

	pcie->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(pcie->clk))
		return PTR_ERR(pcie->clk);

	clk_prepare_enable(pcie->clk);

	pp = &pcie->pp;
	pp->dev = dev;
	platform_set_drvdata(pdev, pcie);

	/* Get the dw-pcie unit configuration/control registers base. */
	base = platform_get_resource_byname(pdev, IORESOURCE_MEM, "ctrl");
	pp->dbi_base = devm_ioremap_resource(dev, base);
	if (IS_ERR(pp->dbi_base)) {
		dev_err(dev, "couldn't remap regs base %p\n", base);
		ret = PTR_ERR(pp->dbi_base);
		goto fail;
	}

	pcie->base = pp->dbi_base + PCIE_VENDOR_REGS_OFFSET;

	ret = armada8k_add_pcie_port(pp, pdev);
	if (ret)
		goto fail;

	return 0;

fail:
	if (!IS_ERR(pcie->clk))
		clk_disable_unprepare(pcie->clk);

	return ret;
}

static const struct of_device_id armada8k_pcie_of_match[] = {
	{ .compatible = "marvell,armada8k-pcie", },
	{},
};
MODULE_DEVICE_TABLE(of, armada8k_pcie_of_match);

static struct platform_driver armada8k_pcie_driver = {
	.probe		= armada8k_pcie_probe,
	.driver = {
		.name	= "armada8k-pcie",
		.of_match_table = of_match_ptr(armada8k_pcie_of_match),
	},
};

module_platform_driver(armada8k_pcie_driver);

MODULE_DESCRIPTION("Armada 8k PCIe host controller driver");
MODULE_AUTHOR("Yehuda Yitshak <yehuday@marvell.com>");
MODULE_AUTHOR("Shadi Ammouri <shadi@marvell.com>");
MODULE_LICENSE("GPL v2");