/*
 * VMEbus User access driver
 *
 * Author: Martyn Welch <martyn.welch@gefanuc.com>
 * Copyright 2008 GE Fanuc Intelligent Platforms Embedded Systems, Inc.
 *
 * Based on work by:
 *   Tom Armistead and Ajit Prem
 *     Copyright 2004 Motorola Inc.
 *
 *
 * 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/cdev.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/ioctl.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/pci.h>
#include <linux/semaphore.h>
#include <linux/spinlock.h>
#include <linux/syscalls.h>
#include <linux/types.h>
#include <linux/version.h>

#include <asm/io.h>
#include <asm/uaccess.h>

#include "../vme.h"
#include "vme_user.h"

static char driver_name[] = "vme_user";

static int bus[USER_BUS_MAX];
static int bus_num;

/* Currently Documentation/devices.txt defines the following for VME:
 *
 * 221 char     VME bus
 *                0 = /dev/bus/vme/m0           First master image
 *                1 = /dev/bus/vme/m1           Second master image
 *                2 = /dev/bus/vme/m2           Third master image
 *                3 = /dev/bus/vme/m3           Fourth master image
 *                4 = /dev/bus/vme/s0           First slave image
 *                5 = /dev/bus/vme/s1           Second slave image
 *                6 = /dev/bus/vme/s2           Third slave image
 *                7 = /dev/bus/vme/s3           Fourth slave image
 *                8 = /dev/bus/vme/ctl          Control
 *
 *              It is expected that all VME bus drivers will use the
 *              same interface.  For interface documentation see
 *              http://www.vmelinux.org/.
 *
 * However the VME driver at http://www.vmelinux.org/ is rather old and doesn't
 * even support the tsi148 chipset (which has 8 master and 8 slave windows).
 * We'll run with this or now as far as possible, however it probably makes
 * sense to get rid of the old mappings and just do everything dynamically.
 *
 * So for now, we'll restrict the driver to providing 4 masters and 4 slaves as
 * defined above and try to support at least some of the interface from
 * http://www.vmelinux.org/ as an alternative drive can be written providing a
 * saner interface later.
 *
 * The vmelinux.org driver never supported slave images, the devices reserved
 * for slaves were repurposed to support all 8 master images on the UniverseII!
 * We shall support 4 masters and 4 slaves with this driver.
 */
#define VME_MAJOR       221     /* VME Major Device Number */
#define VME_DEVS        9       /* Number of dev entries */

#define MASTER_MINOR    0
#define MASTER_MAX      3
#define SLAVE_MINOR     4
#define SLAVE_MAX       7
#define CONTROL_MINOR   8

#define PCI_BUF_SIZE  0x20000   /* Size of one slave image buffer */

/*
 * Structure to handle image related parameters.
 */
typedef struct {
        void __iomem *kern_buf; /* Buffer address in kernel space */
        dma_addr_t pci_buf;     /* Buffer address in PCI address space */
        unsigned long long size_buf;    /* Buffer size */
        struct semaphore sem;   /* Semaphore for locking image */
        struct device *device;  /* Sysfs device */
        struct vme_resource *resource;  /* VME resource */
        int users;              /* Number of current users */
} image_desc_t;
static image_desc_t image[VME_DEVS];

typedef struct {
        unsigned long reads;
        unsigned long writes;
        unsigned long ioctls;
        unsigned long irqs;
        unsigned long berrs;
        unsigned long dmaErrors;
        unsigned long timeouts;
        unsigned long external;
} driver_stats_t;
static driver_stats_t statistics;

struct cdev *vme_user_cdev;             /* Character device */
struct class *vme_user_sysfs_class;     /* Sysfs class */
struct device *vme_user_bridge;         /* Pointer to the bridge device */


static const int type[VME_DEVS] = {     MASTER_MINOR,   MASTER_MINOR,
                                        MASTER_MINOR,   MASTER_MINOR,
                                        SLAVE_MINOR,    SLAVE_MINOR,
                                        SLAVE_MINOR,    SLAVE_MINOR,
                                        CONTROL_MINOR
                                };


static int vme_user_open(struct inode *, struct file *);
static int vme_user_release(struct inode *, struct file *);
static ssize_t vme_user_read(struct file *, char *, size_t, loff_t *);
static ssize_t vme_user_write(struct file *, const char *, size_t, loff_t *);
static loff_t vme_user_llseek(struct file *, loff_t, int);
static int vme_user_ioctl(struct inode *, struct file *, unsigned int,
        unsigned long);

static int __init vme_user_probe(struct device *, int, int);
static int __exit vme_user_remove(struct device *, int, int);

static struct file_operations vme_user_fops = {
        .open = vme_user_open,
        .release = vme_user_release,
        .read = vme_user_read,
        .write = vme_user_write,
        .llseek = vme_user_llseek,
        .ioctl = vme_user_ioctl,
};


/*
 * Reset all the statistic counters
 */
static void reset_counters(void)
{
        statistics.reads = 0;
        statistics.writes = 0;
        statistics.ioctls = 0;
        statistics.irqs = 0;
        statistics.berrs = 0;
        statistics.dmaErrors = 0;
        statistics.timeouts = 0;
}

static int vme_user_open(struct inode *inode, struct file *file)
{
        int err;
        unsigned int minor = MINOR(inode->i_rdev);

        down(&image[minor].sem);
        /* Only allow device to be opened if a resource is allocated */
        if (image[minor].resource == NULL) {
                printk(KERN_ERR "No resources allocated for device\n");
                err = -EINVAL;
                goto err_res;
        }

        /* Increment user count */
        image[minor].users++;

        up(&image[minor].sem);

        return 0;

err_res:
        up(&image[minor].sem);

        return err;
}

static int vme_user_release(struct inode *inode, struct file *file)
{
        unsigned int minor = MINOR(inode->i_rdev);

        down(&image[minor].sem);

        /* Decrement user count */
        image[minor].users--;

        up(&image[minor].sem);

        return 0;
}

/*
 * We are going ot alloc a page during init per window for small transfers.
 * Small transfers will go VME -> buffer -> user space. Larger (more than a
 * page) transfers will lock the user space buffer into memory and then
 * transfer the data directly into the user space buffers.
 */
static ssize_t resource_to_user(int minor, char __user *buf, size_t count,
        loff_t *ppos)
{
        ssize_t retval;
        ssize_t copied = 0;

        if (count <= image[minor].size_buf) {
                /* We copy to kernel buffer */
                copied = vme_master_read(image[minor].resource,
                        image[minor].kern_buf, count, *ppos);
                if (copied < 0) {
                        return (int)copied;
                }

                retval = __copy_to_user(buf, image[minor].kern_buf,
                        (unsigned long)copied);
                if (retval != 0) {
                        copied = (copied - retval);
                        printk("User copy failed\n");
                        return -EINVAL;
                }

        } else {
                /* XXX Need to write this */
                printk("Currently don't support large transfers\n");
                /* Map in pages from userspace */

                /* Call vme_master_read to do the transfer */
                return -EINVAL;
        }

        return copied;
}

/*
 * We are going ot alloc a page during init per window for small transfers.
 * Small transfers will go user space -> buffer -> VME. Larger (more than a
 * page) transfers will lock the user space buffer into memory and then
 * transfer the data directly from the user space buffers out to VME.
 */
static ssize_t resource_from_user(unsigned int minor, const char *buf,
        size_t count, loff_t *ppos)
{
        ssize_t retval;
        ssize_t copied = 0;

        if (count <= image[minor].size_buf) {
                retval = __copy_from_user(image[minor].kern_buf, buf,
                        (unsigned long)count);
                if (retval != 0)
                        copied = (copied - retval);
                else
                        copied = count;

                copied = vme_master_write(image[minor].resource,
                        image[minor].kern_buf, copied, *ppos);
        } else {
                /* XXX Need to write this */
                printk("Currently don't support large transfers\n");
                /* Map in pages from userspace */

                /* Call vme_master_write to do the transfer */
                return -EINVAL;
        }

        return copied;
}

static ssize_t buffer_to_user(unsigned int minor, char __user *buf,
        size_t count, loff_t *ppos)
{
        void __iomem *image_ptr;
        ssize_t retval;

        image_ptr = image[minor].kern_buf + *ppos;

        retval = __copy_to_user(buf, image_ptr, (unsigned long)count);
        if (retval != 0) {
                retval = (count - retval);
                printk(KERN_WARNING "Partial copy to userspace\n");
        } else
                retval = count;

        /* Return number of bytes successfully read */
        return retval;
}

static ssize_t buffer_from_user(unsigned int minor, const char *buf,
        size_t count, loff_t *ppos)
{
        void __iomem *image_ptr;
        size_t retval;

        image_ptr = image[minor].kern_buf + *ppos;

        retval = __copy_from_user(image_ptr, buf, (unsigned long)count);
        if (retval != 0) {
                retval = (count - retval);
                printk(KERN_WARNING "Partial copy to userspace\n");
        } else
                retval = count;

        /* Return number of bytes successfully read */
        return retval;
}

static ssize_t vme_user_read(struct file *file, char *buf, size_t count,
                        loff_t * ppos)
{
        unsigned int minor = MINOR(file->f_dentry->d_inode->i_rdev);
        ssize_t retval;
        size_t image_size;
        size_t okcount;

        down(&image[minor].sem);

        /* XXX Do we *really* want this helper - we can use vme_*_get ? */
        image_size = vme_get_size(image[minor].resource);

        /* Ensure we are starting at a valid location */
        if ((*ppos < 0) || (*ppos > (image_size - 1))) {
                up(&image[minor].sem);
                return 0;
        }

        /* Ensure not reading past end of the image */
        if (*ppos + count > image_size)
                okcount = image_size - *ppos;
        else
                okcount = count;

        switch (type[minor]){
        case MASTER_MINOR:
                retval = resource_to_user(minor, buf, okcount, ppos);
                break;
        case SLAVE_MINOR:
                retval = buffer_to_user(minor, buf, okcount, ppos);
                break;
        default:
                retval = -EINVAL;
        }

        up(&image[minor].sem);

        if (retval > 0)
                *ppos += retval;

        return retval;
}

static ssize_t vme_user_write(struct file *file, const char *buf, size_t count,
                         loff_t *ppos)
{
        unsigned int minor = MINOR(file->f_dentry->d_inode->i_rdev);
        ssize_t retval;
        size_t image_size;
        size_t okcount;

        down(&image[minor].sem);

        image_size = vme_get_size(image[minor].resource);

        /* Ensure we are starting at a valid location */
        if ((*ppos < 0) || (*ppos > (image_size - 1))) {
                up(&image[minor].sem);
                return 0;
        }

        /* Ensure not reading past end of the image */
        if (*ppos + count > image_size)
                okcount = image_size - *ppos;
        else
                okcount = count;

        switch (type[minor]){
        case MASTER_MINOR:
                retval = resource_from_user(minor, buf, okcount, ppos);
                break;
        case SLAVE_MINOR:
                retval = buffer_from_user(minor, buf, okcount, ppos);
                break;
        default:
                retval = -EINVAL;
        }

        up(&image[minor].sem);

        if (retval > 0)
                *ppos += retval;

        return retval;
}

static loff_t vme_user_llseek(struct file *file, loff_t off, int whence)
{
        printk(KERN_ERR "Llseek currently incomplete\n");
        return -EINVAL;
}

/*
 * The ioctls provided by the old VME access method (the one at vmelinux.org)
 * are most certainly wrong as the effectively push the registers layout
 * through to user space. Given that the VME core can handle multiple bridges,
 * with different register layouts this is most certainly not the way to go.
 *
 * We aren't using the structures defined in the Motorola driver either - these
 * are also quite low level, however we should use the definitions that have
 * already been defined.
 */
static int vme_user_ioctl(struct inode *inode, struct file *file,
        unsigned int cmd, unsigned long arg)
{
        struct vme_master master;
        struct vme_slave slave;
        unsigned long copied;
        unsigned int minor = MINOR(inode->i_rdev);
        int retval;
        dma_addr_t pci_addr;

        statistics.ioctls++;

        switch (type[minor]) {
        case CONTROL_MINOR:
                break;
        case MASTER_MINOR:
                switch (cmd) {
                case VME_GET_MASTER:
                        memset(&master, 0, sizeof(struct vme_master));

                        /* XXX  We do not want to push aspace, cycle and width
                         *      to userspace as they are
                         */
                        retval = vme_master_get(image[minor].resource,
                                &(master.enable), &(master.vme_addr),
                                &(master.size), &(master.aspace),
                                &(master.cycle), &(master.dwidth));

                        copied = copy_to_user((char *)arg, &master,
                                sizeof(struct vme_master));
                        if (copied != 0) {
                                printk(KERN_WARNING "Partial copy to "
                                        "userspace\n");
                                return -EFAULT;
                        }

                        return retval;
                        break;

                case VME_SET_MASTER:

                        copied = copy_from_user(&master, (char *)arg,
                                sizeof(master));
                        if (copied != 0) {
                                printk(KERN_WARNING "Partial copy from "
                                        "userspace\n");
                                return -EFAULT;
                        }

                        /* XXX  We do not want to push aspace, cycle and width
                         *      to userspace as they are
                         */
                        return vme_master_set(image[minor].resource,
                                master.enable, master.vme_addr, master.size,
                                master.aspace, master.cycle, master.dwidth);

                        break;
                }
                break;
        case SLAVE_MINOR:
                switch (cmd) {
                case VME_GET_SLAVE:
                        memset(&slave, 0, sizeof(struct vme_slave));

                        /* XXX  We do not want to push aspace, cycle and width
                         *      to userspace as they are
                         */
                        retval = vme_slave_get(image[minor].resource,
                                &(slave.enable), &(slave.vme_addr),
                                &(slave.size), &pci_addr, &(slave.aspace),
                                &(slave.cycle));

                        copied = copy_to_user((char *)arg, &slave,
                                sizeof(struct vme_slave));
                        if (copied != 0) {
                                printk(KERN_WARNING "Partial copy to "
                                        "userspace\n");
                                return -EFAULT;
                        }

                        return retval;
                        break;

                case VME_SET_SLAVE:

                        copied = copy_from_user(&slave, (char *)arg,
                                sizeof(slave));
                        if (copied != 0) {
                                printk(KERN_WARNING "Partial copy from "
                                        "userspace\n");
                                return -EFAULT;
                        }

                        /* XXX  We do not want to push aspace, cycle and width
                         *      to userspace as they are
                         */
                        return vme_slave_set(image[minor].resource,
                                slave.enable, slave.vme_addr, slave.size,
                                image[minor].pci_buf, slave.aspace,
                                slave.cycle);

                        break;
                }
                break;
        }

        return -EINVAL;
}


/*
 * Unallocate a previously allocated buffer
 */
static void buf_unalloc (int num)
{
        if (image[num].kern_buf) {
#ifdef VME_DEBUG
                printk(KERN_DEBUG "UniverseII:Releasing buffer at %p\n",
                        image[num].pci_buf);
#endif

                vme_free_consistent(image[num].resource, image[num].size_buf,
                        image[num].kern_buf, image[num].pci_buf);

                image[num].kern_buf = NULL;
                image[num].pci_buf = 0;
                image[num].size_buf = 0;

#ifdef VME_DEBUG
        } else {
                printk(KERN_DEBUG "UniverseII: Buffer not allocated\n");
#endif
        }
}

static struct vme_driver vme_user_driver = {
        .name = driver_name,
        .probe = vme_user_probe,
        .remove = vme_user_remove,
};


static int __init vme_user_init(void)
{
        int retval = 0;
        int i;
        struct vme_device_id *ids;

        printk(KERN_INFO "VME User Space Access Driver\n");

        if (bus_num == 0) {
                printk(KERN_ERR "%s: No cards, skipping registration\n",
                        driver_name);
                goto err_nocard;
        }

        /* Let's start by supporting one bus, we can support more than one
         * in future revisions if that ever becomes necessary.
         */
        if (bus_num > USER_BUS_MAX) {
                printk(KERN_ERR "%s: Driver only able to handle %d PIO2 "
                        "Cards\n", driver_name, USER_BUS_MAX);
                bus_num = USER_BUS_MAX;
        }


        /* Dynamically create the bind table based on module parameters */
        ids = kmalloc(sizeof(struct vme_device_id) * (bus_num + 1), GFP_KERNEL);
        if (ids == NULL) {
                printk(KERN_ERR "%s: Unable to allocate ID table\n",
                        driver_name);
                goto err_id;
        }

        memset(ids, 0, (sizeof(struct vme_device_id) * (bus_num + 1)));

        for (i = 0; i < bus_num; i++) {
                ids[i].bus = bus[i];
                /*
                 * We register the driver against the slot occupied by *this*
                 * card, since it's really a low level way of controlling
                 * the VME bridge
                 */
                ids[i].slot = VME_SLOT_CURRENT;
        }

        vme_user_driver.bind_table = ids;

        retval = vme_register_driver(&vme_user_driver);
        if (retval != 0)
                goto err_reg;

        return retval;

        vme_unregister_driver(&vme_user_driver);
err_reg:
        kfree(ids);
err_id:
err_nocard:
        return retval;
}

/*
 * In this simple access driver, the old behaviour is being preserved as much
 * as practical. We will therefore reserve the buffers and request the images
 * here so that we don't have to do it later.
 */
static int __init vme_user_probe(struct device *dev, int cur_bus, int cur_slot)
{
        int i, err;
        char name[8];

        /* Save pointer to the bridge device */
        if (vme_user_bridge != NULL) {
                printk(KERN_ERR "%s: Driver can only be loaded for 1 device\n",
                        driver_name);
                err = -EINVAL;
                goto err_dev;
        }
        vme_user_bridge = dev;

        /* Initialise descriptors */
        for (i = 0; i < VME_DEVS; i++) {
                image[i].kern_buf = NULL;
                image[i].pci_buf = 0;
                init_MUTEX(&(image[i].sem));
                image[i].device = NULL;
                image[i].resource = NULL;
                image[i].users = 0;
        }

        /* Initialise statistics counters */
        reset_counters();

        /* Assign major and minor numbers for the driver */
        err = register_chrdev_region(MKDEV(VME_MAJOR, 0), VME_DEVS,
                driver_name);
        if (err) {
                printk(KERN_WARNING "%s: Error getting Major Number %d for "
                "driver.\n", driver_name, VME_MAJOR);
                goto err_region;
        }

        /* Register the driver as a char device */
        vme_user_cdev = cdev_alloc();
        vme_user_cdev->ops = &vme_user_fops;
        vme_user_cdev->owner = THIS_MODULE;
        err = cdev_add(vme_user_cdev, MKDEV(VME_MAJOR, 0), VME_DEVS);
        if (err) {
                printk(KERN_WARNING "%s: cdev_all failed\n", driver_name);
                goto err_char;
        }

        /* Request slave resources and allocate buffers (128kB wide) */
        for (i = SLAVE_MINOR; i < (SLAVE_MAX + 1); i++) {
                /* XXX Need to properly request attributes */
                image[i].resource = vme_slave_request(vme_user_bridge,
                        VME_A16, VME_SCT);
                if (image[i].resource == NULL) {
                        printk(KERN_WARNING "Unable to allocate slave "
                                "resource\n");
                        goto err_slave;
                }
                image[i].size_buf = PCI_BUF_SIZE;
                image[i].kern_buf = vme_alloc_consistent(image[i].resource,
                        image[i].size_buf, &(image[i].pci_buf));
                if (image[i].kern_buf == NULL) {
                        printk(KERN_WARNING "Unable to allocate memory for "
                                "buffer\n");
                        image[i].pci_buf = 0;
                        vme_slave_free(image[i].resource);
                        err = -ENOMEM;
                        goto err_slave;
                }
        }

        /*
         * Request master resources allocate page sized buffers for small
         * reads and writes
         */
        for (i = MASTER_MINOR; i < (MASTER_MAX + 1); i++) {
                /* XXX Need to properly request attributes */
                image[i].resource = vme_master_request(vme_user_bridge,
                        VME_A32, VME_SCT, VME_D32);
                if (image[i].resource == NULL) {
                        printk(KERN_WARNING "Unable to allocate master "
                                "resource\n");
                        goto err_master;
                }
        }

        /* Create sysfs entries - on udev systems this creates the dev files */
        vme_user_sysfs_class = class_create(THIS_MODULE, driver_name);
        if (IS_ERR(vme_user_sysfs_class)) {
                printk(KERN_ERR "Error creating vme_user class.\n");
                err = PTR_ERR(vme_user_sysfs_class);
                goto err_class;
        }

        /* Add sysfs Entries */
        for (i=0; i<VME_DEVS; i++) {
                switch (type[i]) {
                case MASTER_MINOR:
                        sprintf(name,"bus/vme/m%%d");
                        break;
                case CONTROL_MINOR:
                        sprintf(name,"bus/vme/ctl");
                        break;
                case SLAVE_MINOR:
                        sprintf(name,"bus/vme/s%%d");
                        break;
                default:
                        err = -EINVAL;
                        goto err_sysfs;
                        break;
                }

                image[i].device =
                        device_create(vme_user_sysfs_class, NULL,
                                MKDEV(VME_MAJOR, i), NULL, name,
                                (type[i] == SLAVE_MINOR)? i - (MASTER_MAX + 1) : i);
                if (IS_ERR(image[i].device)) {
                        printk("%s: Error creating sysfs device\n",
                                driver_name);
                        err = PTR_ERR(image[i].device);
                        goto err_sysfs;
                }
        }

        return 0;

        /* Ensure counter set correcty to destroy all sysfs devices */
        i = VME_DEVS;
err_sysfs:
        while (i > 0){
                i--;
                device_destroy(vme_user_sysfs_class, MKDEV(VME_MAJOR, i));
        }
        class_destroy(vme_user_sysfs_class);

        /* Ensure counter set correcty to unalloc all master windows */
        i = MASTER_MAX + 1;
err_master:
        while (i > MASTER_MINOR) {
                i--;
                vme_master_free(image[i].resource);
        }

        /*
         * Ensure counter set correcty to unalloc all slave windows and buffers
         */
        i = SLAVE_MAX + 1;
err_slave:
        while (i > SLAVE_MINOR) {
                i--;
                vme_slave_free(image[i].resource);
                buf_unalloc(i);
        }
err_class:
        cdev_del(vme_user_cdev);
err_char:
        unregister_chrdev_region(MKDEV(VME_MAJOR, 0), VME_DEVS);
err_region:
err_dev:
        return err;
}

static int __exit vme_user_remove(struct device *dev, int cur_bus, int cur_slot)
{
        int i;

        /* Remove sysfs Entries */
        for(i=0; i<VME_DEVS; i++) {
                device_destroy(vme_user_sysfs_class, MKDEV(VME_MAJOR, i));
        }
        class_destroy(vme_user_sysfs_class);

        for (i = SLAVE_MINOR; i < (SLAVE_MAX + 1); i++) {
                vme_slave_set(image[i].resource, 0, 0, 0, 0, VME_A32, 0);
                vme_slave_free(image[i].resource);
                buf_unalloc(i);
        }

        /* Unregister device driver */
        cdev_del(vme_user_cdev);

        /* Unregiser the major and minor device numbers */
        unregister_chrdev_region(MKDEV(VME_MAJOR, 0), VME_DEVS);

        return 0;
}

static void __exit vme_user_exit(void)
{
        vme_unregister_driver(&vme_user_driver);

        kfree(vme_user_driver.bind_table);
}


MODULE_PARM_DESC(bus, "Enumeration of VMEbus to which the driver is connected");
module_param_array(bus, int, &bus_num, 0);

MODULE_DESCRIPTION("VME User Space Access Driver");
MODULE_AUTHOR("Martyn Welch <martyn.welch@gefanuc.com");
MODULE_LICENSE("GPL");

module_init(vme_user_init);
module_exit(vme_user_exit);