/*
 * xHCI host controller driver
 *
 * Copyright (C) 2008 Intel Corp.
 *
 * Author: Sarah Sharp
 * Some code borrowed from the Linux EHCI driver.
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/irq.h>
#include <linux/module.h>

#include "xhci.h"

#define DRIVER_AUTHOR "Sarah Sharp"
#define DRIVER_DESC "'eXtensible' Host Controller (xHC) Driver"

/* TODO: copied from ehci-hcd.c - can this be refactored? */
/*
 * handshake - spin reading hc until handshake completes or fails
 * @ptr: address of hc register to be read
 * @mask: bits to look at in result of read
 * @done: value of those bits when handshake succeeds
 * @usec: timeout in microseconds
 *
 * Returns negative errno, or zero on success
 *
 * Success happens when the "mask" bits have the specified value (hardware
 * handshake done).  There are two failure modes:  "usec" have passed (major
 * hardware flakeout), or the register reads as all-ones (hardware removed).
 */
static int handshake(struct xhci_hcd *xhci, void __iomem *ptr,
		      u32 mask, u32 done, int usec)
{
	u32	result;

	do {
		result = xhci_readl(xhci, ptr);
		if (result == ~(u32)0)		/* card removed */
			return -ENODEV;
		result &= mask;
		if (result == done)
			return 0;
		udelay(1);
		usec--;
	} while (usec > 0);
	return -ETIMEDOUT;
}

/*
 * Force HC into halt state.
 *
 * Disable any IRQs and clear the run/stop bit.
 * HC will complete any current and actively pipelined transactions, and
 * should halt within 16 microframes of the run/stop bit being cleared.
 * Read HC Halted bit in the status register to see when the HC is finished.
 * XXX: shouldn't we set HC_STATE_HALT here somewhere?
 */
int xhci_halt(struct xhci_hcd *xhci)
{
	u32 halted;
	u32 cmd;
	u32 mask;

	xhci_dbg(xhci, "// Halt the HC\n");
	/* Disable all interrupts from the host controller */
	mask = ~(XHCI_IRQS);
	halted = xhci_readl(xhci, &xhci->op_regs->status) & STS_HALT;
	if (!halted)
		mask &= ~CMD_RUN;

	cmd = xhci_readl(xhci, &xhci->op_regs->command);
	cmd &= mask;
	xhci_writel(xhci, cmd, &xhci->op_regs->command);

	return handshake(xhci, &xhci->op_regs->status,
			STS_HALT, STS_HALT, XHCI_MAX_HALT_USEC);
}

/*
 * Reset a halted HC, and set the internal HC state to HC_STATE_HALT.
 *
 * This resets pipelines, timers, counters, state machines, etc.
 * Transactions will be terminated immediately, and operational registers
 * will be set to their defaults.
 */
int xhci_reset(struct xhci_hcd *xhci)
{
	u32 command;
	u32 state;

	state = xhci_readl(xhci, &xhci->op_regs->status);
	BUG_ON((state & STS_HALT) == 0);

	xhci_dbg(xhci, "// Reset the HC\n");
	command = xhci_readl(xhci, &xhci->op_regs->command);
	command |= CMD_RESET;
	xhci_writel(xhci, command, &xhci->op_regs->command);
	/* XXX: Why does EHCI set this here?  Shouldn't other code do this? */
	xhci_to_hcd(xhci)->state = HC_STATE_HALT;

	return handshake(xhci, &xhci->op_regs->command, CMD_RESET, 0, 250 * 1000);
}

/*
 * Stop the HC from processing the endpoint queues.
 */
static void xhci_quiesce(struct xhci_hcd *xhci)
{
	/*
	 * Queues are per endpoint, so we need to disable an endpoint or slot.
	 *
	 * To disable a slot, we need to insert a disable slot command on the
	 * command ring and ring the doorbell.  This will also free any internal
	 * resources associated with the slot (which might not be what we want).
	 *
	 * A Release Endpoint command sounds better - doesn't free internal HC
	 * memory, but removes the endpoints from the schedule and releases the
	 * bandwidth, disables the doorbells, and clears the endpoint enable
	 * flag.  Usually used prior to a set interface command.
	 *
	 * TODO: Implement after command ring code is done.
	 */
	BUG_ON(!HC_IS_RUNNING(xhci_to_hcd(xhci)->state));
	xhci_dbg(xhci, "Finished quiescing -- code not written yet\n");
}

#if 0
/* Set up MSI-X table for entry 0 (may claim other entries later) */
static int xhci_setup_msix(struct xhci_hcd *xhci)
{
	int ret;
	struct pci_dev *pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);

	xhci->msix_count = 0;
	/* XXX: did I do this right?  ixgbe does kcalloc for more than one */
	xhci->msix_entries = kmalloc(sizeof(struct msix_entry), GFP_KERNEL);
	if (!xhci->msix_entries) {
		xhci_err(xhci, "Failed to allocate MSI-X entries\n");
		return -ENOMEM;
	}
	xhci->msix_entries[0].entry = 0;

	ret = pci_enable_msix(pdev, xhci->msix_entries, xhci->msix_count);
	if (ret) {
		xhci_err(xhci, "Failed to enable MSI-X\n");
		goto free_entries;
	}

	/*
	 * Pass the xhci pointer value as the request_irq "cookie".
	 * If more irqs are added, this will need to be unique for each one.
	 */
	ret = request_irq(xhci->msix_entries[0].vector, &xhci_irq, 0,
			"xHCI", xhci_to_hcd(xhci));
	if (ret) {
		xhci_err(xhci, "Failed to allocate MSI-X interrupt\n");
		goto disable_msix;
	}
	xhci_dbg(xhci, "Finished setting up MSI-X\n");
	return 0;

disable_msix:
	pci_disable_msix(pdev);
free_entries:
	kfree(xhci->msix_entries);
	xhci->msix_entries = NULL;
	return ret;
}

/* XXX: code duplication; can xhci_setup_msix call this? */
/* Free any IRQs and disable MSI-X */
static void xhci_cleanup_msix(struct xhci_hcd *xhci)
{
	struct pci_dev *pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);
	if (!xhci->msix_entries)
		return;

	free_irq(xhci->msix_entries[0].vector, xhci);
	pci_disable_msix(pdev);
	kfree(xhci->msix_entries);
	xhci->msix_entries = NULL;
	xhci_dbg(xhci, "Finished cleaning up MSI-X\n");
}
#endif

/*
 * Initialize memory for HCD and xHC (one-time init).
 *
 * Program the PAGESIZE register, initialize the device context array, create
 * device contexts (?), set up a command ring segment (or two?), create event
 * ring (one for now).
 */
int xhci_init(struct usb_hcd *hcd)
{
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
	int retval = 0;

	xhci_dbg(xhci, "xhci_init\n");
	spin_lock_init(&xhci->lock);
	retval = xhci_mem_init(xhci, GFP_KERNEL);
	xhci_dbg(xhci, "Finished xhci_init\n");

	return retval;
}

/*
 * Start the HC after it was halted.
 *
 * This function is called by the USB core when the HC driver is added.
 * Its opposite is xhci_stop().
 *
 * xhci_init() must be called once before this function can be called.
 * Reset the HC, enable device slot contexts, program DCBAAP, and
 * set command ring pointer and event ring pointer.
 *
 * Setup MSI-X vectors and enable interrupts.
 */
int xhci_run(struct usb_hcd *hcd)
{
	u32 temp;
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
	xhci_dbg(xhci, "xhci_run\n");

#if 0	/* FIXME: MSI not setup yet */
	/* Do this at the very last minute */
	ret = xhci_setup_msix(xhci);
	if (!ret)
		return ret;

	return -ENOSYS;
#endif
	xhci_dbg(xhci, "// Set the interrupt modulation register\n");
	temp = xhci_readl(xhci, &xhci->ir_set->irq_control);
	temp &= 0xffff;
	temp |= (u32) 160;
	xhci_writel(xhci, temp, &xhci->ir_set->irq_control);

	/* Set the HCD state before we enable the irqs */
	hcd->state = HC_STATE_RUNNING;
	temp = xhci_readl(xhci, &xhci->op_regs->command);
	temp |= (CMD_EIE);
	xhci_dbg(xhci, "// Enable interrupts, cmd = 0x%x.\n",
			temp);
	xhci_writel(xhci, temp, &xhci->op_regs->command);

	temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
	xhci_dbg(xhci, "// Enabling event ring interrupter 0x%x"
			" by writing 0x%x to irq_pending\n",
			(unsigned int) xhci->ir_set,
			(unsigned int) ER_IRQ_ENABLE(temp));
	xhci_writel(xhci, ER_IRQ_ENABLE(temp),
			&xhci->ir_set->irq_pending);
	xhci_print_ir_set(xhci, xhci->ir_set, 0);

	temp = xhci_readl(xhci, &xhci->op_regs->command);
	temp |= (CMD_RUN);
	xhci_dbg(xhci, "// Turn on HC, cmd = 0x%x.\n",
			temp);
	xhci_writel(xhci, temp, &xhci->op_regs->command);
	/* Flush PCI posted writes */
	temp = xhci_readl(xhci, &xhci->op_regs->command);
	xhci_dbg(xhci, "// @%x = 0x%x\n",
			(unsigned int) &xhci->op_regs->command, temp);

	xhci_dbg(xhci, "Finished xhci_run\n");
	return 0;
}

/*
 * Stop xHCI driver.
 *
 * This function is called by the USB core when the HC driver is removed.
 * Its opposite is xhci_run().
 *
 * Disable device contexts, disable IRQs, and quiesce the HC.
 * Reset the HC, finish any completed transactions, and cleanup memory.
 */
void xhci_stop(struct usb_hcd *hcd)
{
	u32 temp;
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);

	spin_lock_irq(&xhci->lock);
	if (HC_IS_RUNNING(hcd->state))
		xhci_quiesce(xhci);
	xhci_halt(xhci);
	xhci_reset(xhci);
	spin_unlock_irq(&xhci->lock);

#if 0	/* No MSI yet */
	xhci_cleanup_msix(xhci);
#endif
	xhci_dbg(xhci, "// Disabling event ring interrupts\n");
	temp = xhci_readl(xhci, &xhci->op_regs->status);
	xhci_writel(xhci, temp & ~STS_EINT, &xhci->op_regs->status);
	temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
	xhci_writel(xhci, ER_IRQ_DISABLE(temp),
			&xhci->ir_set->irq_pending);
	xhci_print_ir_set(xhci, xhci->ir_set, 0);

	xhci_dbg(xhci, "cleaning up memory\n");
	xhci_mem_cleanup(xhci);
	xhci_dbg(xhci, "xhci_stop completed - status = %x\n",
		    xhci_readl(xhci, &xhci->op_regs->status));
}

/*
 * Shutdown HC (not bus-specific)
 *
 * This is called when the machine is rebooting or halting.  We assume that the
 * machine will be powered off, and the HC's internal state will be reset.
 * Don't bother to free memory.
 */
void xhci_shutdown(struct usb_hcd *hcd)
{
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);

	spin_lock_irq(&xhci->lock);
	xhci_halt(xhci);
	spin_unlock_irq(&xhci->lock);

#if 0
	xhci_cleanup_msix(xhci);
#endif

	xhci_dbg(xhci, "xhci_shutdown completed - status = %x\n",
		    xhci_readl(xhci, &xhci->op_regs->status));
}

int xhci_get_frame(struct usb_hcd *hcd)
{
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
	/* EHCI mods by the periodic size.  Why? */
	return xhci_readl(xhci, &xhci->run_regs->microframe_index) >> 3;
}

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_LICENSE("GPL");

static int __init xhci_hcd_init(void)
{
#ifdef CONFIG_PCI
	int retval = 0;

	retval = xhci_register_pci();

	if (retval < 0) {
		printk(KERN_DEBUG "Problem registering PCI driver.");
		return retval;
	}
#endif
	return 0;
}
module_init(xhci_hcd_init);

static void __exit xhci_hcd_cleanup(void)
{
#ifdef CONFIG_PCI
	xhci_unregister_pci();
#endif
}
module_exit(xhci_hcd_cleanup);