/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2005-2006 Silicon Graphics, Inc.  All Rights Reserved.
 */

/* This file contains the master driver module for use by SGI IOC4 subdrivers.
 *
 * It allocates any resources shared between multiple subdevices, and
 * provides accessor functions (where needed) and the like for those
 * resources.  It also provides a mechanism for the subdevice modules
 * to support loading and unloading.
 *
 * Non-shared resources (e.g. external interrupt A_INT_OUT register page
 * alias, serial port and UART registers) are handled by the subdevice
 * modules themselves.
 *
 * This is all necessary because IOC4 is not implemented as a multi-function
 * PCI device, but an amalgamation of disparate registers for several
 * types of device (ATA, serial, external interrupts).  The normal
 * resource management in the kernel doesn't have quite the right interfaces
 * to handle this situation (e.g. multiple modules can't claim the same
 * PCI ID), thus this IOC4 master module.
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/ioc4.h>
#include <linux/ktime.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/time.h>
#include <asm/io.h>

/***************
 * Definitions *
 ***************/

/* Tweakable values */

/* PCI bus speed detection/calibration */
#define IOC4_CALIBRATE_COUNT 63         /* Calibration cycle period */
#define IOC4_CALIBRATE_CYCLES 256       /* Average over this many cycles */
#define IOC4_CALIBRATE_DISCARD 2        /* Discard first few cycles */
#define IOC4_CALIBRATE_LOW_MHZ 25       /* Lower bound on bus speed sanity */
#define IOC4_CALIBRATE_HIGH_MHZ 75      /* Upper bound on bus speed sanity */
#define IOC4_CALIBRATE_DEFAULT_MHZ 66   /* Assumed if sanity check fails */

/************************
 * Submodule management *
 ************************/

static DEFINE_MUTEX(ioc4_mutex);

static LIST_HEAD(ioc4_devices);
static LIST_HEAD(ioc4_submodules);

/* Register an IOC4 submodule */
int
ioc4_register_submodule(struct ioc4_submodule *is)
{
        struct ioc4_driver_data *idd;

        mutex_lock(&ioc4_mutex);
        list_add(&is->is_list, &ioc4_submodules);

        /* Initialize submodule for each IOC4 */
        if (!is->is_probe)
                goto out;

        list_for_each_entry(idd, &ioc4_devices, idd_list) {
                if (is->is_probe(idd)) {
                        printk(KERN_WARNING
                               "%s: IOC4 submodule %s probe failed "
                               "for pci_dev %s",
                               __func__, module_name(is->is_owner),
                               pci_name(idd->idd_pdev));
                }
        }
 out:
        mutex_unlock(&ioc4_mutex);
        return 0;
}

/* Unregister an IOC4 submodule */
void
ioc4_unregister_submodule(struct ioc4_submodule *is)
{
        struct ioc4_driver_data *idd;

        mutex_lock(&ioc4_mutex);
        list_del(&is->is_list);

        /* Remove submodule for each IOC4 */
        if (!is->is_remove)
                goto out;

        list_for_each_entry(idd, &ioc4_devices, idd_list) {
                if (is->is_remove(idd)) {
                        printk(KERN_WARNING
                               "%s: IOC4 submodule %s remove failed "
                               "for pci_dev %s.\n",
                               __func__, module_name(is->is_owner),
                               pci_name(idd->idd_pdev));
                }
        }
 out:
        mutex_unlock(&ioc4_mutex);
}

/*********************
 * Device management *
 *********************/

#define IOC4_CALIBRATE_LOW_LIMIT \
        (1000*IOC4_EXTINT_COUNT_DIVISOR/IOC4_CALIBRATE_LOW_MHZ)
#define IOC4_CALIBRATE_HIGH_LIMIT \
        (1000*IOC4_EXTINT_COUNT_DIVISOR/IOC4_CALIBRATE_HIGH_MHZ)
#define IOC4_CALIBRATE_DEFAULT \
        (1000*IOC4_EXTINT_COUNT_DIVISOR/IOC4_CALIBRATE_DEFAULT_MHZ)

#define IOC4_CALIBRATE_END \
        (IOC4_CALIBRATE_CYCLES + IOC4_CALIBRATE_DISCARD)

#define IOC4_INT_OUT_MODE_TOGGLE 0x7    /* Toggle INT_OUT every COUNT+1 ticks */

/* Determines external interrupt output clock period of the PCI bus an
 * IOC4 is attached to.  This value can be used to determine the PCI
 * bus speed.
 *
 * IOC4 has a design feature that various internal timers are derived from
 * the PCI bus clock.  This causes IOC4 device drivers to need to take the
 * bus speed into account when setting various register values (e.g. INT_OUT
 * register COUNT field, UART divisors, etc).  Since this information is
 * needed by several subdrivers, it is determined by the main IOC4 driver,
 * even though the following code utilizes external interrupt registers
 * to perform the speed calculation.
 */
static void
ioc4_clock_calibrate(struct ioc4_driver_data *idd)
{
        union ioc4_int_out int_out;
        union ioc4_gpcr gpcr;
        unsigned int state, last_state = 1;
        struct timespec start_ts, end_ts;
        uint64_t start, end, period;
        unsigned int count = 0;

        /* Enable output */
        gpcr.raw = 0;
        gpcr.fields.dir = IOC4_GPCR_DIR_0;
        gpcr.fields.int_out_en = 1;
        writel(gpcr.raw, &idd->idd_misc_regs->gpcr_s.raw);

        /* Reset to power-on state */
        writel(0, &idd->idd_misc_regs->int_out.raw);
        mmiowb();

        /* Set up square wave */
        int_out.raw = 0;
        int_out.fields.count = IOC4_CALIBRATE_COUNT;
        int_out.fields.mode = IOC4_INT_OUT_MODE_TOGGLE;
        int_out.fields.diag = 0;
        writel(int_out.raw, &idd->idd_misc_regs->int_out.raw);
        mmiowb();

        /* Check square wave period averaged over some number of cycles */
        do {
                int_out.raw = readl(&idd->idd_misc_regs->int_out.raw);
                state = int_out.fields.int_out;
                if (!last_state && state) {
                        count++;
                        if (count == IOC4_CALIBRATE_END) {
                                ktime_get_ts(&end_ts);
                                break;
                        } else if (count == IOC4_CALIBRATE_DISCARD)
                                ktime_get_ts(&start_ts);
                }
                last_state = state;
        } while (1);

        /* Calculation rearranged to preserve intermediate precision.
         * Logically:
         * 1. "end - start" gives us the measurement period over all
         *    the square wave cycles.
         * 2. Divide by number of square wave cycles to get the period
         *    of a square wave cycle.
         * 3. Divide by 2*(int_out.fields.count+1), which is the formula
         *    by which the IOC4 generates the square wave, to get the
         *    period of an IOC4 INT_OUT count.
         */
        end = end_ts.tv_sec * NSEC_PER_SEC + end_ts.tv_nsec;
        start = start_ts.tv_sec * NSEC_PER_SEC + start_ts.tv_nsec;
        period = (end - start) /
                (IOC4_CALIBRATE_CYCLES * 2 * (IOC4_CALIBRATE_COUNT + 1));

        /* Bounds check the result. */
        if (period > IOC4_CALIBRATE_LOW_LIMIT ||
            period < IOC4_CALIBRATE_HIGH_LIMIT) {
                printk(KERN_INFO
                       "IOC4 %s: Clock calibration failed.  Assuming"
                       "PCI clock is %d ns.\n",
                       pci_name(idd->idd_pdev),
                       IOC4_CALIBRATE_DEFAULT / IOC4_EXTINT_COUNT_DIVISOR);
                period = IOC4_CALIBRATE_DEFAULT;
        } else {
                u64 ns = period;

                do_div(ns, IOC4_EXTINT_COUNT_DIVISOR);
                printk(KERN_DEBUG
                       "IOC4 %s: PCI clock is %llu ns.\n",
                       pci_name(idd->idd_pdev), (unsigned long long)ns);
        }

        /* Remember results.  We store the extint clock period rather
         * than the PCI clock period so that greater precision is
         * retained.  Divide by IOC4_EXTINT_COUNT_DIVISOR to get
         * PCI clock period.
         */
        idd->count_period = period;
}

/* There are three variants of IOC4 cards: IO9, IO10, and PCI-RT.
 * Each brings out different combinations of IOC4 signals, thus.
 * the IOC4 subdrivers need to know to which we're attached.
 *
 * We look for the presence of a SCSI (IO9) or SATA (IO10) controller
 * on the same PCI bus at slot number 3 to differentiate IO9 from IO10.
 * If neither is present, it's a PCI-RT.
 */
static unsigned int
ioc4_variant(struct ioc4_driver_data *idd)
{
        struct pci_dev *pdev = NULL;
        int found = 0;

        /* IO9: Look for a QLogic ISP 12160 at the same bus and slot 3. */
        do {
                pdev = pci_get_device(PCI_VENDOR_ID_QLOGIC,
                                      PCI_DEVICE_ID_QLOGIC_ISP12160, pdev);
                if (pdev &&
                    idd->idd_pdev->bus->number == pdev->bus->number &&
                    3 == PCI_SLOT(pdev->devfn))
                        found = 1;
        } while (pdev && !found);
        if (NULL != pdev) {
                pci_dev_put(pdev);
                return IOC4_VARIANT_IO9;
        }

        /* IO10: Look for a Vitesse VSC 7174 at the same bus and slot 3. */
        pdev = NULL;
        do {
                pdev = pci_get_device(PCI_VENDOR_ID_VITESSE,
                                      PCI_DEVICE_ID_VITESSE_VSC7174, pdev);
                if (pdev &&
                    idd->idd_pdev->bus->number == pdev->bus->number &&
                    3 == PCI_SLOT(pdev->devfn))
                        found = 1;
        } while (pdev && !found);
        if (NULL != pdev) {
                pci_dev_put(pdev);
                return IOC4_VARIANT_IO10;
        }

        /* PCI-RT: No SCSI/SATA controller will be present */
        return IOC4_VARIANT_PCI_RT;
}

static void
ioc4_load_modules(struct work_struct *work)
{
        request_module("sgiioc4");
}

static DECLARE_WORK(ioc4_load_modules_work, ioc4_load_modules);

/* Adds a new instance of an IOC4 card */
static int
ioc4_probe(struct pci_dev *pdev, const struct pci_device_id *pci_id)
{
        struct ioc4_driver_data *idd;
        struct ioc4_submodule *is;
        uint32_t pcmd;
        int ret;

        /* Enable IOC4 and take ownership of it */
        if ((ret = pci_enable_device(pdev))) {
                printk(KERN_WARNING
                       "%s: Failed to enable IOC4 device for pci_dev %s.\n",
                       __func__, pci_name(pdev));
                goto out;
        }
        pci_set_master(pdev);

        /* Set up per-IOC4 data */
        idd = kmalloc(sizeof(struct ioc4_driver_data), GFP_KERNEL);
        if (!idd) {
                printk(KERN_WARNING
                       "%s: Failed to allocate IOC4 data for pci_dev %s.\n",
                       __func__, pci_name(pdev));
                ret = -ENODEV;
                goto out_idd;
        }
        idd->idd_pdev = pdev;
        idd->idd_pci_id = pci_id;

        /* Map IOC4 misc registers.  These are shared between subdevices
         * so the main IOC4 module manages them.
         */
        idd->idd_bar0 = pci_resource_start(idd->idd_pdev, 0);
        if (!idd->idd_bar0) {
                printk(KERN_WARNING
                       "%s: Unable to find IOC4 misc resource "
                       "for pci_dev %s.\n",
                       __func__, pci_name(idd->idd_pdev));
                ret = -ENODEV;
                goto out_pci;
        }
        if (!request_mem_region(idd->idd_bar0, sizeof(struct ioc4_misc_regs),
                            "ioc4_misc")) {
                printk(KERN_WARNING
                       "%s: Unable to request IOC4 misc region "
                       "for pci_dev %s.\n",
                       __func__, pci_name(idd->idd_pdev));
                ret = -ENODEV;
                goto out_pci;
        }
        idd->idd_misc_regs = ioremap(idd->idd_bar0,
                                     sizeof(struct ioc4_misc_regs));
        if (!idd->idd_misc_regs) {
                printk(KERN_WARNING
                       "%s: Unable to remap IOC4 misc region "
                       "for pci_dev %s.\n",
                       __func__, pci_name(idd->idd_pdev));
                ret = -ENODEV;
                goto out_misc_region;
        }

        /* Failsafe portion of per-IOC4 initialization */

        /* Detect card variant */
        idd->idd_variant = ioc4_variant(idd);
        printk(KERN_INFO "IOC4 %s: %s card detected.\n", pci_name(pdev),
               idd->idd_variant == IOC4_VARIANT_IO9 ? "IO9" :
               idd->idd_variant == IOC4_VARIANT_PCI_RT ? "PCI-RT" :
               idd->idd_variant == IOC4_VARIANT_IO10 ? "IO10" : "unknown");

        /* Initialize IOC4 */
        pci_read_config_dword(idd->idd_pdev, PCI_COMMAND, &pcmd);
        pci_write_config_dword(idd->idd_pdev, PCI_COMMAND,
                               pcmd | PCI_COMMAND_PARITY | PCI_COMMAND_SERR);

        /* Determine PCI clock */
        ioc4_clock_calibrate(idd);

        /* Disable/clear all interrupts.  Need to do this here lest
         * one submodule request the shared IOC4 IRQ, but interrupt
         * is generated by a different subdevice.
         */
        /* Disable */
        writel(~0, &idd->idd_misc_regs->other_iec.raw);
        writel(~0, &idd->idd_misc_regs->sio_iec);
        /* Clear (i.e. acknowledge) */
        writel(~0, &idd->idd_misc_regs->other_ir.raw);
        writel(~0, &idd->idd_misc_regs->sio_ir);

        /* Track PCI-device specific data */
        idd->idd_serial_data = NULL;
        pci_set_drvdata(idd->idd_pdev, idd);

        mutex_lock(&ioc4_mutex);
        list_add_tail(&idd->idd_list, &ioc4_devices);

        /* Add this IOC4 to all submodules */
        list_for_each_entry(is, &ioc4_submodules, is_list) {
                if (is->is_probe && is->is_probe(idd)) {
                        printk(KERN_WARNING
                               "%s: IOC4 submodule 0x%s probe failed "
                               "for pci_dev %s.\n",
                               __func__, module_name(is->is_owner),
                               pci_name(idd->idd_pdev));
                }
        }
        mutex_unlock(&ioc4_mutex);

        /* Request sgiioc4 IDE driver on boards that bring that functionality
         * off of IOC4.  The root filesystem may be hosted on a drive connected
         * to IOC4, so we need to make sure the sgiioc4 driver is loaded as it
         * won't be picked up by modprobes due to the ioc4 module owning the
         * PCI device.
         */
        if (idd->idd_variant != IOC4_VARIANT_PCI_RT) {
                /* Request the module from a work procedure as the modprobe
                 * goes out to a userland helper and that will hang if done
                 * directly from ioc4_probe().
                 */
                printk(KERN_INFO "IOC4 loading sgiioc4 submodule\n");
                schedule_work(&ioc4_load_modules_work);
        }

        return 0;

out_misc_region:
        release_mem_region(idd->idd_bar0, sizeof(struct ioc4_misc_regs));
out_pci:
        kfree(idd);
out_idd:
        pci_disable_device(pdev);
out:
        return ret;
}

/* Removes a particular instance of an IOC4 card. */
static void
ioc4_remove(struct pci_dev *pdev)
{
        struct ioc4_submodule *is;
        struct ioc4_driver_data *idd;

        idd = pci_get_drvdata(pdev);

        /* Remove this IOC4 from all submodules */
        mutex_lock(&ioc4_mutex);
        list_for_each_entry(is, &ioc4_submodules, is_list) {
                if (is->is_remove && is->is_remove(idd)) {
                        printk(KERN_WARNING
                               "%s: IOC4 submodule 0x%s remove failed "
                               "for pci_dev %s.\n",
                               __func__, module_name(is->is_owner),
                               pci_name(idd->idd_pdev));
                }
        }
        mutex_unlock(&ioc4_mutex);

        /* Release resources */
        iounmap(idd->idd_misc_regs);
        if (!idd->idd_bar0) {
                printk(KERN_WARNING
                       "%s: Unable to get IOC4 misc mapping for pci_dev %s. "
                       "Device removal may be incomplete.\n",
                       __func__, pci_name(idd->idd_pdev));
        }
        release_mem_region(idd->idd_bar0, sizeof(struct ioc4_misc_regs));

        /* Disable IOC4 and relinquish */
        pci_disable_device(pdev);

        /* Remove and free driver data */
        mutex_lock(&ioc4_mutex);
        list_del(&idd->idd_list);
        mutex_unlock(&ioc4_mutex);
        kfree(idd);
}

static struct pci_device_id ioc4_id_table[] = {
        {PCI_VENDOR_ID_SGI, PCI_DEVICE_ID_SGI_IOC4, PCI_ANY_ID,
         PCI_ANY_ID, 0x0b4000, 0xFFFFFF},
        {0}
};

static struct pci_driver ioc4_driver = {
        .name = "IOC4",
        .id_table = ioc4_id_table,
        .probe = ioc4_probe,
        .remove = ioc4_remove,
};

MODULE_DEVICE_TABLE(pci, ioc4_id_table);

/*********************
 * Module management *
 *********************/

/* Module load */
static int __init
ioc4_init(void)
{
        return pci_register_driver(&ioc4_driver);
}

/* Module unload */
static void __exit
ioc4_exit(void)
{
        /* Ensure ioc4_load_modules() has completed before exiting */
        flush_work(&ioc4_load_modules_work);
        pci_unregister_driver(&ioc4_driver);
}

module_init(ioc4_init);
module_exit(ioc4_exit);

MODULE_AUTHOR("Brent Casavant - Silicon Graphics, Inc. <bcasavan@sgi.com>");
MODULE_DESCRIPTION("PCI driver master module for SGI IOC4 Base-IO Card");
MODULE_LICENSE("GPL");

EXPORT_SYMBOL(ioc4_register_submodule);
EXPORT_SYMBOL(ioc4_unregister_submodule);