/*
 * Copyright 2007, Michael Ellerman, IBM Corporation.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */


#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/msi.h>
#include <linux/of_platform.h>

#include <asm/dcr.h>
#include <asm/machdep.h>
#include <asm/prom.h>


/*
 * MSIC registers, specified as offsets from dcr_base
 */
#define MSIC_CTRL_REG	0x0

/* Base Address registers specify FIFO location in BE memory */
#define MSIC_BASE_ADDR_HI_REG	0x3
#define MSIC_BASE_ADDR_LO_REG	0x4

/* Hold the read/write offsets into the FIFO */
#define MSIC_READ_OFFSET_REG	0x5
#define MSIC_WRITE_OFFSET_REG	0x6


/* MSIC control register flags */
#define MSIC_CTRL_ENABLE		0x0001
#define MSIC_CTRL_FIFO_FULL_ENABLE	0x0002
#define MSIC_CTRL_IRQ_ENABLE		0x0008
#define MSIC_CTRL_FULL_STOP_ENABLE	0x0010

/*
 * The MSIC can be configured to use a FIFO of 32KB, 64KB, 128KB or 256KB.
 * Currently we're using a 64KB FIFO size.
 */
#define MSIC_FIFO_SIZE_SHIFT	16
#define MSIC_FIFO_SIZE_BYTES	(1 << MSIC_FIFO_SIZE_SHIFT)

/*
 * To configure the FIFO size as (1 << n) bytes, we write (n - 15) into bits
 * 8-9 of the MSIC control reg.
 */
#define MSIC_CTRL_FIFO_SIZE	(((MSIC_FIFO_SIZE_SHIFT - 15) << 8) & 0x300)

/*
 * We need to mask the read/write offsets to make sure they stay within
 * the bounds of the FIFO. Also they should always be 16-byte aligned.
 */
#define MSIC_FIFO_SIZE_MASK	((MSIC_FIFO_SIZE_BYTES - 1) & ~0xFu)

/* Each entry in the FIFO is 16 bytes, the first 4 bytes hold the irq # */
#define MSIC_FIFO_ENTRY_SIZE	0x10


struct axon_msic {
	struct irq_host *irq_host;
	__le32 *fifo_virt;
	dma_addr_t fifo_phys;
	dcr_host_t dcr_host;
	u32 read_offset;
};

static void msic_dcr_write(struct axon_msic *msic, unsigned int dcr_n, u32 val)
{
	pr_debug("axon_msi: dcr_write(0x%x, 0x%x)\n", val, dcr_n);

	dcr_write(msic->dcr_host, dcr_n, val);
}

static void axon_msi_cascade(unsigned int irq, struct irq_desc *desc)
{
	struct axon_msic *msic = get_irq_data(irq);
	u32 write_offset, msi;
	int idx;

	write_offset = dcr_read(msic->dcr_host, MSIC_WRITE_OFFSET_REG);
	pr_debug("axon_msi: original write_offset 0x%x\n", write_offset);

	/* write_offset doesn't wrap properly, so we have to mask it */
	write_offset &= MSIC_FIFO_SIZE_MASK;

	while (msic->read_offset != write_offset) {
		idx  = msic->read_offset / sizeof(__le32);
		msi  = le32_to_cpu(msic->fifo_virt[idx]);
		msi &= 0xFFFF;

		pr_debug("axon_msi: woff %x roff %x msi %x\n",
			  write_offset, msic->read_offset, msi);

		msic->read_offset += MSIC_FIFO_ENTRY_SIZE;
		msic->read_offset &= MSIC_FIFO_SIZE_MASK;

		if (msi < NR_IRQS && irq_map[msi].host == msic->irq_host)
			generic_handle_irq(msi);
		else
			pr_debug("axon_msi: invalid irq 0x%x!\n", msi);
	}

	desc->chip->eoi(irq);
}

static struct axon_msic *find_msi_translator(struct pci_dev *dev)
{
	struct irq_host *irq_host;
	struct device_node *dn, *tmp;
	const phandle *ph;
	struct axon_msic *msic = NULL;

	dn = of_node_get(pci_device_to_OF_node(dev));
	if (!dn) {
		dev_dbg(&dev->dev, "axon_msi: no pci_dn found\n");
		return NULL;
	}

	for (; dn; tmp = of_get_parent(dn), of_node_put(dn), dn = tmp) {
		ph = of_get_property(dn, "msi-translator", NULL);
		if (ph)
			break;
	}

	if (!ph) {
		dev_dbg(&dev->dev,
			"axon_msi: no msi-translator property found\n");
		goto out_error;
	}

	tmp = dn;
	dn = of_find_node_by_phandle(*ph);
	of_node_put(tmp);
	if (!dn) {
		dev_dbg(&dev->dev,
			"axon_msi: msi-translator doesn't point to a node\n");
		goto out_error;
	}

	irq_host = irq_find_host(dn);
	if (!irq_host) {
		dev_dbg(&dev->dev, "axon_msi: no irq_host found for node %s\n",
			dn->full_name);
		goto out_error;
	}

	msic = irq_host->host_data;

out_error:
	of_node_put(dn);

	return msic;
}

static int axon_msi_check_device(struct pci_dev *dev, int nvec, int type)
{
	if (!find_msi_translator(dev))
		return -ENODEV;

	return 0;
}

static int setup_msi_msg_address(struct pci_dev *dev, struct msi_msg *msg)
{
	struct device_node *dn, *tmp;
	struct msi_desc *entry;
	int len;
	const u32 *prop;

	dn = of_node_get(pci_device_to_OF_node(dev));
	if (!dn) {
		dev_dbg(&dev->dev, "axon_msi: no pci_dn found\n");
		return -ENODEV;
	}

	entry = list_first_entry(&dev->msi_list, struct msi_desc, list);

	for (; dn; tmp = of_get_parent(dn), of_node_put(dn), dn = tmp) {
		if (entry->msi_attrib.is_64) {
			prop = of_get_property(dn, "msi-address-64", &len);
			if (prop)
				break;
		}

		prop = of_get_property(dn, "msi-address-32", &len);
		if (prop)
			break;
	}

	if (!prop) {
		dev_dbg(&dev->dev,
			"axon_msi: no msi-address-(32|64) properties found\n");
		return -ENOENT;
	}

	switch (len) {
	case 8:
		msg->address_hi = prop[0];
		msg->address_lo = prop[1];
		break;
	case 4:
		msg->address_hi = 0;
		msg->address_lo = prop[0];
		break;
	default:
		dev_dbg(&dev->dev,
			"axon_msi: malformed msi-address-(32|64) property\n");
		of_node_put(dn);
		return -EINVAL;
	}

	of_node_put(dn);

	return 0;
}

static int axon_msi_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
{
	unsigned int virq, rc;
	struct msi_desc *entry;
	struct msi_msg msg;
	struct axon_msic *msic;

	msic = find_msi_translator(dev);
	if (!msic)
		return -ENODEV;

	rc = setup_msi_msg_address(dev, &msg);
	if (rc)
		return rc;

	/* We rely on being able to stash a virq in a u16 */
	BUILD_BUG_ON(NR_IRQS > 65536);

	list_for_each_entry(entry, &dev->msi_list, list) {
		virq = irq_create_direct_mapping(msic->irq_host);
		if (virq == NO_IRQ) {
			dev_warn(&dev->dev,
				 "axon_msi: virq allocation failed!\n");
			return -1;
		}
		dev_dbg(&dev->dev, "axon_msi: allocated virq 0x%x\n", virq);

		set_irq_msi(virq, entry);
		msg.data = virq;
		write_msi_msg(virq, &msg);
	}

	return 0;
}

static void axon_msi_teardown_msi_irqs(struct pci_dev *dev)
{
	struct msi_desc *entry;

	dev_dbg(&dev->dev, "axon_msi: tearing down msi irqs\n");

	list_for_each_entry(entry, &dev->msi_list, list) {
		if (entry->irq == NO_IRQ)
			continue;

		set_irq_msi(entry->irq, NULL);
		irq_dispose_mapping(entry->irq);
	}
}

static struct irq_chip msic_irq_chip = {
	.mask		= mask_msi_irq,
	.unmask		= unmask_msi_irq,
	.shutdown	= unmask_msi_irq,
	.typename	= "AXON-MSI",
};

static int msic_host_map(struct irq_host *h, unsigned int virq,
			 irq_hw_number_t hw)
{
	set_irq_chip_and_handler(virq, &msic_irq_chip, handle_simple_irq);

	return 0;
}

static struct irq_host_ops msic_host_ops = {
	.map	= msic_host_map,
};

static int axon_msi_shutdown(struct of_device *device)
{
	struct axon_msic *msic = device->dev.platform_data;
	u32 tmp;

	pr_debug("axon_msi: disabling %s\n",
		  msic->irq_host->of_node->full_name);
	tmp  = dcr_read(msic->dcr_host, MSIC_CTRL_REG);
	tmp &= ~MSIC_CTRL_ENABLE & ~MSIC_CTRL_IRQ_ENABLE;
	msic_dcr_write(msic, MSIC_CTRL_REG, tmp);

	return 0;
}

static int axon_msi_probe(struct of_device *device,
			  const struct of_device_id *device_id)
{
	struct device_node *dn = device->node;
	struct axon_msic *msic;
	unsigned int virq;
	int dcr_base, dcr_len;

	pr_debug("axon_msi: setting up dn %s\n", dn->full_name);

	msic = kzalloc(sizeof(struct axon_msic), GFP_KERNEL);
	if (!msic) {
		printk(KERN_ERR "axon_msi: couldn't allocate msic for %s\n",
		       dn->full_name);
		goto out;
	}

	dcr_base = dcr_resource_start(dn, 0);
	dcr_len = dcr_resource_len(dn, 0);

	if (dcr_base == 0 || dcr_len == 0) {
		printk(KERN_ERR
		       "axon_msi: couldn't parse dcr properties on %s\n",
			dn->full_name);
		goto out;
	}

	msic->dcr_host = dcr_map(dn, dcr_base, dcr_len);
	if (!DCR_MAP_OK(msic->dcr_host)) {
		printk(KERN_ERR "axon_msi: dcr_map failed for %s\n",
		       dn->full_name);
		goto out_free_msic;
	}

	msic->fifo_virt = dma_alloc_coherent(&device->dev, MSIC_FIFO_SIZE_BYTES,
					     &msic->fifo_phys, GFP_KERNEL);
	if (!msic->fifo_virt) {
		printk(KERN_ERR "axon_msi: couldn't allocate fifo for %s\n",
		       dn->full_name);
		goto out_free_msic;
	}

	msic->irq_host = irq_alloc_host(of_node_get(dn), IRQ_HOST_MAP_NOMAP,
					NR_IRQS, &msic_host_ops, 0);
	if (!msic->irq_host) {
		printk(KERN_ERR "axon_msi: couldn't allocate irq_host for %s\n",
		       dn->full_name);
		goto out_free_fifo;
	}

	msic->irq_host->host_data = msic;

	virq = irq_of_parse_and_map(dn, 0);
	if (virq == NO_IRQ) {
		printk(KERN_ERR "axon_msi: irq parse and map failed for %s\n",
		       dn->full_name);
		goto out_free_host;
	}

	set_irq_data(virq, msic);
	set_irq_chained_handler(virq, axon_msi_cascade);
	pr_debug("axon_msi: irq 0x%x setup for axon_msi\n", virq);

	/* Enable the MSIC hardware */
	msic_dcr_write(msic, MSIC_BASE_ADDR_HI_REG, msic->fifo_phys >> 32);
	msic_dcr_write(msic, MSIC_BASE_ADDR_LO_REG,
				  msic->fifo_phys & 0xFFFFFFFF);
	msic_dcr_write(msic, MSIC_CTRL_REG,
			MSIC_CTRL_IRQ_ENABLE | MSIC_CTRL_ENABLE |
			MSIC_CTRL_FIFO_SIZE);

	device->dev.platform_data = msic;

	ppc_md.setup_msi_irqs = axon_msi_setup_msi_irqs;
	ppc_md.teardown_msi_irqs = axon_msi_teardown_msi_irqs;
	ppc_md.msi_check_device = axon_msi_check_device;

	printk(KERN_DEBUG "axon_msi: setup MSIC on %s\n", dn->full_name);

	return 0;

out_free_host:
	kfree(msic->irq_host);
out_free_fifo:
	dma_free_coherent(&device->dev, MSIC_FIFO_SIZE_BYTES, msic->fifo_virt,
			  msic->fifo_phys);
out_free_msic:
	kfree(msic);
out:

	return -1;
}

static const struct of_device_id axon_msi_device_id[] = {
	{
		.compatible	= "ibm,axon-msic"
	},
	{}
};

static struct of_platform_driver axon_msi_driver = {
	.match_table	= axon_msi_device_id,
	.probe		= axon_msi_probe,
	.shutdown	= axon_msi_shutdown,
	.driver		= {
		.name	= "axon-msi"
	},
};

static int __init axon_msi_init(void)
{
	return of_register_platform_driver(&axon_msi_driver);
}
subsys_initcall(axon_msi_init);