/*
 * SN Platform system controller communication support
 *
 * 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) 2004, 2006 Silicon Graphics, Inc. All rights reserved.
 */

/*
 * System controller communication driver
 *
 * This driver allows a user process to communicate with the system
 * controller (a.k.a. "IRouter") network in an SGI SN system.
 */

#include <linux/interrupt.h>
#include <linux/sched/signal.h>
#include <linux/device.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <asm/sn/io.h>
#include <asm/sn/sn_sal.h>
#include <asm/sn/module.h>
#include <asm/sn/geo.h>
#include <asm/sn/nodepda.h>
#include "snsc.h"

#define SYSCTL_BASENAME "snsc"

#define SCDRV_BUFSZ     2048
#define SCDRV_TIMEOUT   1000

static DEFINE_MUTEX(scdrv_mutex);
static irqreturn_t
scdrv_interrupt(int irq, void *subch_data)
{
        struct subch_data_s *sd = subch_data;
        unsigned long flags;
        int status;

        spin_lock_irqsave(&sd->sd_rlock, flags);
        spin_lock(&sd->sd_wlock);
        status = ia64_sn_irtr_intr(sd->sd_nasid, sd->sd_subch);

        if (status > 0) {
                if (status & SAL_IROUTER_INTR_RECV) {
                        wake_up(&sd->sd_rq);
                }
                if (status & SAL_IROUTER_INTR_XMIT) {
                        ia64_sn_irtr_intr_disable
                            (sd->sd_nasid, sd->sd_subch,
                             SAL_IROUTER_INTR_XMIT);
                        wake_up(&sd->sd_wq);
                }
        }
        spin_unlock(&sd->sd_wlock);
        spin_unlock_irqrestore(&sd->sd_rlock, flags);
        return IRQ_HANDLED;
}

/*
 * scdrv_open
 *
 * Reserve a subchannel for system controller communication.
 */

static int
scdrv_open(struct inode *inode, struct file *file)
{
        struct sysctl_data_s *scd;
        struct subch_data_s *sd;
        int rv;

        /* look up device info for this device file */
        scd = container_of(inode->i_cdev, struct sysctl_data_s, scd_cdev);

        /* allocate memory for subchannel data */
        sd = kzalloc(sizeof (struct subch_data_s), GFP_KERNEL);
        if (sd == NULL) {
                printk("%s: couldn't allocate subchannel data\n",
                       __func__);
                return -ENOMEM;
        }

        /* initialize subch_data_s fields */
        sd->sd_nasid = scd->scd_nasid;
        sd->sd_subch = ia64_sn_irtr_open(scd->scd_nasid);

        if (sd->sd_subch < 0) {
                kfree(sd);
                printk("%s: couldn't allocate subchannel\n", __func__);
                return -EBUSY;
        }

        spin_lock_init(&sd->sd_rlock);
        spin_lock_init(&sd->sd_wlock);
        init_waitqueue_head(&sd->sd_rq);
        init_waitqueue_head(&sd->sd_wq);
        sema_init(&sd->sd_rbs, 1);
        sema_init(&sd->sd_wbs, 1);

        file->private_data = sd;

        /* hook this subchannel up to the system controller interrupt */
        mutex_lock(&scdrv_mutex);
        rv = request_irq(SGI_UART_VECTOR, scdrv_interrupt,
                         IRQF_SHARED, SYSCTL_BASENAME, sd);
        if (rv) {
                ia64_sn_irtr_close(sd->sd_nasid, sd->sd_subch);
                kfree(sd);
                printk("%s: irq request failed (%d)\n", __func__, rv);
                mutex_unlock(&scdrv_mutex);
                return -EBUSY;
        }
        mutex_unlock(&scdrv_mutex);
        return 0;
}

/*
 * scdrv_release
 *
 * Release a previously-reserved subchannel.
 */

static int
scdrv_release(struct inode *inode, struct file *file)
{
        struct subch_data_s *sd = (struct subch_data_s *) file->private_data;
        int rv;

        /* free the interrupt */
        free_irq(SGI_UART_VECTOR, sd);

        /* ask SAL to close the subchannel */
        rv = ia64_sn_irtr_close(sd->sd_nasid, sd->sd_subch);

        kfree(sd);
        return rv;
}

/*
 * scdrv_read
 *
 * Called to read bytes from the open IRouter pipe.
 *
 */

static inline int
read_status_check(struct subch_data_s *sd, int *len)
{
        return ia64_sn_irtr_recv(sd->sd_nasid, sd->sd_subch, sd->sd_rb, len);
}

static ssize_t
scdrv_read(struct file *file, char __user *buf, size_t count, loff_t *f_pos)
{
        int status;
        int len;
        unsigned long flags;
        struct subch_data_s *sd = (struct subch_data_s *) file->private_data;

        /* try to get control of the read buffer */
        if (down_trylock(&sd->sd_rbs)) {
                /* somebody else has it now;
                 * if we're non-blocking, then exit...
                 */
                if (file->f_flags & O_NONBLOCK) {
                        return -EAGAIN;
                }
                /* ...or if we want to block, then do so here */
                if (down_interruptible(&sd->sd_rbs)) {
                        /* something went wrong with wait */
                        return -ERESTARTSYS;
                }
        }

        /* anything to read? */
        len = CHUNKSIZE;
        spin_lock_irqsave(&sd->sd_rlock, flags);
        status = read_status_check(sd, &len);

        /* if not, and we're blocking I/O, loop */
        while (status < 0) {
                DECLARE_WAITQUEUE(wait, current);

                if (file->f_flags & O_NONBLOCK) {
                        spin_unlock_irqrestore(&sd->sd_rlock, flags);
                        up(&sd->sd_rbs);
                        return -EAGAIN;
                }

                len = CHUNKSIZE;
                set_current_state(TASK_INTERRUPTIBLE);
                add_wait_queue(&sd->sd_rq, &wait);
                spin_unlock_irqrestore(&sd->sd_rlock, flags);

                schedule_timeout(msecs_to_jiffies(SCDRV_TIMEOUT));

                remove_wait_queue(&sd->sd_rq, &wait);
                if (signal_pending(current)) {
                        /* wait was interrupted */
                        up(&sd->sd_rbs);
                        return -ERESTARTSYS;
                }

                spin_lock_irqsave(&sd->sd_rlock, flags);
                status = read_status_check(sd, &len);
        }
        spin_unlock_irqrestore(&sd->sd_rlock, flags);

        if (len > 0) {
                /* we read something in the last read_status_check(); copy
                 * it out to user space
                 */
                if (count < len) {
                        pr_debug("%s: only accepting %d of %d bytes\n",
                                 __func__, (int) count, len);
                }
                len = min((int) count, len);
                if (copy_to_user(buf, sd->sd_rb, len))
                        len = -EFAULT;
        }

        /* release the read buffer and wake anyone who might be
         * waiting for it
         */
        up(&sd->sd_rbs);

        /* return the number of characters read in */
        return len;
}

/*
 * scdrv_write
 *
 * Writes a chunk of an IRouter packet (or other system controller data)
 * to the system controller.
 *
 */
static inline int
write_status_check(struct subch_data_s *sd, int count)
{
        return ia64_sn_irtr_send(sd->sd_nasid, sd->sd_subch, sd->sd_wb, count);
}

static ssize_t
scdrv_write(struct file *file, const char __user *buf,
            size_t count, loff_t *f_pos)
{
        unsigned long flags;
        int status;
        struct subch_data_s *sd = (struct subch_data_s *) file->private_data;

        /* try to get control of the write buffer */
        if (down_trylock(&sd->sd_wbs)) {
                /* somebody else has it now;
                 * if we're non-blocking, then exit...
                 */
                if (file->f_flags & O_NONBLOCK) {
                        return -EAGAIN;
                }
                /* ...or if we want to block, then do so here */
                if (down_interruptible(&sd->sd_wbs)) {
                        /* something went wrong with wait */
                        return -ERESTARTSYS;
                }
        }

        count = min((int) count, CHUNKSIZE);
        if (copy_from_user(sd->sd_wb, buf, count)) {
                up(&sd->sd_wbs);
                return -EFAULT;
        }

        /* try to send the buffer */
        spin_lock_irqsave(&sd->sd_wlock, flags);
        status = write_status_check(sd, count);

        /* if we failed, and we want to block, then loop */
        while (status <= 0) {
                DECLARE_WAITQUEUE(wait, current);

                if (file->f_flags & O_NONBLOCK) {
                        spin_unlock_irqrestore(&sd->sd_wlock, flags);
                        up(&sd->sd_wbs);
                        return -EAGAIN;
                }

                set_current_state(TASK_INTERRUPTIBLE);
                add_wait_queue(&sd->sd_wq, &wait);
                spin_unlock_irqrestore(&sd->sd_wlock, flags);

                schedule_timeout(msecs_to_jiffies(SCDRV_TIMEOUT));

                remove_wait_queue(&sd->sd_wq, &wait);
                if (signal_pending(current)) {
                        /* wait was interrupted */
                        up(&sd->sd_wbs);
                        return -ERESTARTSYS;
                }

                spin_lock_irqsave(&sd->sd_wlock, flags);
                status = write_status_check(sd, count);
        }
        spin_unlock_irqrestore(&sd->sd_wlock, flags);

        /* release the write buffer and wake anyone who's waiting for it */
        up(&sd->sd_wbs);

        /* return the number of characters accepted (should be the complete
         * "chunk" as requested)
         */
        if ((status >= 0) && (status < count)) {
                pr_debug("Didn't accept the full chunk; %d of %d\n",
                         status, (int) count);
        }
        return status;
}

static __poll_t
scdrv_poll(struct file *file, struct poll_table_struct *wait)
{
        __poll_t mask = 0;
        int status = 0;
        struct subch_data_s *sd = (struct subch_data_s *) file->private_data;
        unsigned long flags;

        poll_wait(file, &sd->sd_rq, wait);
        poll_wait(file, &sd->sd_wq, wait);

        spin_lock_irqsave(&sd->sd_rlock, flags);
        spin_lock(&sd->sd_wlock);
        status = ia64_sn_irtr_intr(sd->sd_nasid, sd->sd_subch);
        spin_unlock(&sd->sd_wlock);
        spin_unlock_irqrestore(&sd->sd_rlock, flags);

        if (status > 0) {
                if (status & SAL_IROUTER_INTR_RECV) {
                        mask |= EPOLLIN | EPOLLRDNORM;
                }
                if (status & SAL_IROUTER_INTR_XMIT) {
                        mask |= EPOLLOUT | EPOLLWRNORM;
                }
        }

        return mask;
}

static const struct file_operations scdrv_fops = {
        .owner =        THIS_MODULE,
        .read =         scdrv_read,
        .write =        scdrv_write,
        .poll =         scdrv_poll,
        .open =         scdrv_open,
        .release =      scdrv_release,
        .llseek =       noop_llseek,
};

static struct class *snsc_class;

/*
 * scdrv_init
 *
 * Called at boot time to initialize the system controller communication
 * facility.
 */
int __init
scdrv_init(void)
{
        geoid_t geoid;
        cnodeid_t cnode;
        char devname[32];
        char *devnamep;
        struct sysctl_data_s *scd;
        void *salbuf;
        dev_t first_dev, dev;
        nasid_t event_nasid;

        if (!ia64_platform_is("sn2"))
                return -ENODEV;

        event_nasid = ia64_sn_get_console_nasid();

        snsc_class = class_create(THIS_MODULE, SYSCTL_BASENAME);
        if (IS_ERR(snsc_class)) {
                printk("%s: failed to allocate class\n", __func__);
                return PTR_ERR(snsc_class);
        }

        if (alloc_chrdev_region(&first_dev, 0, num_cnodes,
                                SYSCTL_BASENAME) < 0) {
                printk("%s: failed to register SN system controller device\n",
                       __func__);
                return -ENODEV;
        }

        for (cnode = 0; cnode < num_cnodes; cnode++) {
                        geoid = cnodeid_get_geoid(cnode);
                        devnamep = devname;
                        format_module_id(devnamep, geo_module(geoid),
                                         MODULE_FORMAT_BRIEF);
                        devnamep = devname + strlen(devname);
                        sprintf(devnamep, "^%d#%d", geo_slot(geoid),
                                geo_slab(geoid));

                        /* allocate sysctl device data */
                        scd = kzalloc(sizeof (struct sysctl_data_s),
                                      GFP_KERNEL);
                        if (!scd) {
                                printk("%s: failed to allocate device info"
                                       "for %s/%s\n", __func__,
                                       SYSCTL_BASENAME, devname);
                                continue;
                        }

                        /* initialize sysctl device data fields */
                        scd->scd_nasid = cnodeid_to_nasid(cnode);
                        if (!(salbuf = kmalloc(SCDRV_BUFSZ, GFP_KERNEL))) {
                                printk("%s: failed to allocate driver buffer"
                                       "(%s%s)\n", __func__,
                                       SYSCTL_BASENAME, devname);
                                kfree(scd);
                                continue;
                        }

                        if (ia64_sn_irtr_init(scd->scd_nasid, salbuf,
                                              SCDRV_BUFSZ) < 0) {
                                printk
                                    ("%s: failed to initialize SAL for"
                                     " system controller communication"
                                     " (%s/%s): outdated PROM?\n",
                                     __func__, SYSCTL_BASENAME, devname);
                                kfree(scd);
                                kfree(salbuf);
                                continue;
                        }

                        dev = first_dev + cnode;
                        cdev_init(&scd->scd_cdev, &scdrv_fops);
                        if (cdev_add(&scd->scd_cdev, dev, 1)) {
                                printk("%s: failed to register system"
                                       " controller device (%s%s)\n",
                                       __func__, SYSCTL_BASENAME, devname);
                                kfree(scd);
                                kfree(salbuf);
                                continue;
                        }

                        device_create(snsc_class, NULL, dev, NULL,
                                      "%s", devname);

                        ia64_sn_irtr_intr_enable(scd->scd_nasid,
                                                 0 /*ignored */ ,
                                                 SAL_IROUTER_INTR_RECV);

                        /* on the console nasid, prepare to receive
                         * system controller environmental events
                         */
                        if(scd->scd_nasid == event_nasid) {
                                scdrv_event_init(scd);
                        }
        }
        return 0;
}
device_initcall(scdrv_init);