/*
 * drivers/sbus/char/jsflash.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds    (drivers/char/mem.c)
 *  Copyright (C) 1997  Eddie C. Dost           (drivers/sbus/char/flash.c)
 *  Copyright (C) 1997-2000 Pavel Machek <pavel@ucw.cz>   (drivers/block/nbd.c)
 *  Copyright (C) 1999-2000 Pete Zaitcev
 *
 * This driver is used to program OS into a Flash SIMM on
 * Krups and Espresso platforms.
 *
 * TODO: do not allow erase/programming if file systems are mounted.
 * TODO: Erase/program both banks of a 8MB SIMM.
 *
 * It is anticipated that programming an OS Flash will be a routine
 * procedure. In the same time it is exceedingly dangerous because
 * a user can program its OBP flash with OS image and effectively
 * kill the machine.
 *
 * This driver uses an interface different from Eddie's flash.c
 * as a silly safeguard.
 *
 * XXX The flash.c manipulates page caching characteristics in a certain
 * dubious way; also it assumes that remap_pfn_range() can remap
 * PCI bus locations, which may be false. ioremap() must be used
 * instead. We should discuss this.
 */

#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/fcntl.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/genhd.h>
#include <linux/blkdev.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/io.h>
#include <asm/pcic.h>
#include <asm/oplib.h>

#include <asm/jsflash.h>                /* ioctl arguments. <linux/> ?? */
#define JSFIDSZ         (sizeof(struct jsflash_ident_arg))
#define JSFPRGSZ        (sizeof(struct jsflash_program_arg))

/*
 * Our device numbers have no business in system headers.
 * The only thing a user knows is the device name /dev/jsflash.
 *
 * Block devices are laid out like this:
 *   minor+0    - Bootstrap, for 8MB SIMM 0x20400000[0x800000]
 *   minor+1    - Filesystem to mount, normally 0x20400400[0x7ffc00]
 *   minor+2    - Whole flash area for any case... 0x20000000[0x01000000]
 * Total 3 minors per flash device.
 *
 * It is easier to have static size vectors, so we define
 * a total minor range JSF_MAX, which must cover all minors.
 */
/* character device */
#define JSF_MINOR       178     /* 178 is registered with hpa */
/* block device */
#define JSF_MAX          3      /* 3 minors wasted total so far. */
#define JSF_NPART        3      /* 3 minors per flash device */
#define JSF_PART_BITS    2      /* 2 bits of minors to cover JSF_NPART */
#define JSF_PART_MASK    0x3    /* 2 bits mask */

static DEFINE_MUTEX(jsf_mutex);

/*
 * Access functions.
 * We could ioremap(), but it's easier this way.
 */
static unsigned int jsf_inl(unsigned long addr)
{
        unsigned long retval;

        __asm__ __volatile__("lda [%1] %2, %0\n\t" :
                                "=r" (retval) :
                                "r" (addr), "i" (ASI_M_BYPASS));
        return retval;
}

static void jsf_outl(unsigned long addr, __u32 data)
{

        __asm__ __volatile__("sta %0, [%1] %2\n\t" : :
                                "r" (data), "r" (addr), "i" (ASI_M_BYPASS) :
                                "memory");
}

/*
 * soft carrier
 */

struct jsfd_part {
        unsigned long dbase;
        unsigned long dsize;
};

struct jsflash {
        unsigned long base;
        unsigned long size;
        unsigned long busy;             /* In use? */
        struct jsflash_ident_arg id;
        /* int mbase; */                /* Minor base, typically zero */
        struct jsfd_part dv[JSF_NPART];
};

/*
 * We do not map normal memory or obio as a safety precaution.
 * But offsets are real, for ease of userland programming.
 */
#define JSF_BASE_TOP    0x30000000
#define JSF_BASE_ALL    0x20000000

#define JSF_BASE_JK     0x20400000

/*
 */
static struct gendisk *jsfd_disk[JSF_MAX];

/*
 * Let's pretend we may have several of these...
 */
static struct jsflash jsf0;

/*
 * Wait for AMD to finish its embedded algorithm.
 * We use the Toggle bit DQ6 (0x40) because it does not
 * depend on the data value as /DATA bit DQ7 does.
 *
 * XXX Do we need any timeout here? So far it never hanged, beware broken hw.
 */
static void jsf_wait(unsigned long p) {
        unsigned int x1, x2;

        for (;;) {
                x1 = jsf_inl(p);
                x2 = jsf_inl(p);
                if ((x1 & 0x40404040) == (x2 & 0x40404040)) return;
        }
}

/*
 * Programming will only work if Flash is clean,
 * we leave it to the programmer application.
 *
 * AMD must be programmed one byte at a time;
 * thus, Simple Tech SIMM must be written 4 bytes at a time.
 *
 * Write waits for the chip to become ready after the write
 * was finished. This is done so that application would read
 * consistent data after the write is done.
 */
static void jsf_write4(unsigned long fa, u32 data) {

        jsf_outl(fa, 0xAAAAAAAA);               /* Unlock 1 Write 1 */
        jsf_outl(fa, 0x55555555);               /* Unlock 1 Write 2 */
        jsf_outl(fa, 0xA0A0A0A0);               /* Byte Program */
        jsf_outl(fa, data);

        jsf_wait(fa);
}

/*
 */
static void jsfd_read(char *buf, unsigned long p, size_t togo) {
        union byte4 {
                char s[4];
                unsigned int n;
        } b;

        while (togo >= 4) {
                togo -= 4;
                b.n = jsf_inl(p);
                memcpy(buf, b.s, 4);
                p += 4;
                buf += 4;
        }
}

static void jsfd_do_request(struct request_queue *q)
{
        struct request *req;

        req = blk_fetch_request(q);
        while (req) {
                struct jsfd_part *jdp = req->rq_disk->private_data;
                unsigned long offset = blk_rq_pos(req) << 9;
                size_t len = blk_rq_cur_bytes(req);
                int err = -EIO;

                if ((offset + len) > jdp->dsize)
                        goto end;

                if (rq_data_dir(req) != READ) {
                        printk(KERN_ERR "jsfd: write\n");
                        goto end;
                }

                if ((jdp->dbase & 0xff000000) != 0x20000000) {
                        printk(KERN_ERR "jsfd: bad base %x\n", (int)jdp->dbase);
                        goto end;
                }

                jsfd_read(req->buffer, jdp->dbase + offset, len);
                err = 0;
        end:
                if (!__blk_end_request_cur(req, err))
                        req = blk_fetch_request(q);
        }
}

/*
 * The memory devices use the full 32/64 bits of the offset, and so we cannot
 * check against negative addresses: they are ok. The return value is weird,
 * though, in that case (0).
 *
 * also note that seeking relative to the "end of file" isn't supported:
 * it has no meaning, so it returns -EINVAL.
 */
static loff_t jsf_lseek(struct file * file, loff_t offset, int orig)
{
        loff_t ret;

        mutex_lock(&jsf_mutex);
        switch (orig) {
                case 0:
                        file->f_pos = offset;
                        ret = file->f_pos;
                        break;
                case 1:
                        file->f_pos += offset;
                        ret = file->f_pos;
                        break;
                default:
                        ret = -EINVAL;
        }
        mutex_unlock(&jsf_mutex);
        return ret;
}

/*
 * OS SIMM Cannot be read in other size but a 32bits word.
 */
static ssize_t jsf_read(struct file * file, char __user * buf, 
    size_t togo, loff_t *ppos)
{
        unsigned long p = *ppos;
        char __user *tmp = buf;

        union byte4 {
                char s[4];
                unsigned int n;
        } b;

        if (p < JSF_BASE_ALL || p >= JSF_BASE_TOP) {
                return 0;
        }

        if ((p + togo) < p      /* wrap */
           || (p + togo) >= JSF_BASE_TOP) {
                togo = JSF_BASE_TOP - p;
        }

        if (p < JSF_BASE_ALL && togo != 0) {
#if 0 /* __bzero XXX */
                size_t x = JSF_BASE_ALL - p;
                if (x > togo) x = togo;
                clear_user(tmp, x);
                tmp += x;
                p += x;
                togo -= x;
#else
                /*
                 * Implementation of clear_user() calls __bzero
                 * without regard to modversions,
                 * so we cannot build a module.
                 */
                return 0;
#endif
        }

        while (togo >= 4) {
                togo -= 4;
                b.n = jsf_inl(p);
                if (copy_to_user(tmp, b.s, 4))
                        return -EFAULT;
                tmp += 4;
                p += 4;
        }

        /*
         * XXX Small togo may remain if 1 byte is ordered.
         * It would be nice if we did a word size read and unpacked it.
         */

        *ppos = p;
        return tmp-buf;
}

static ssize_t jsf_write(struct file * file, const char __user * buf,
    size_t count, loff_t *ppos)
{
        return -ENOSPC;
}

/*
 */
static int jsf_ioctl_erase(unsigned long arg)
{
        unsigned long p;

        /* p = jsf0.base;       hits wrong bank */
        p = 0x20400000;

        jsf_outl(p, 0xAAAAAAAA);                /* Unlock 1 Write 1 */
        jsf_outl(p, 0x55555555);                /* Unlock 1 Write 2 */
        jsf_outl(p, 0x80808080);                /* Erase setup */
        jsf_outl(p, 0xAAAAAAAA);                /* Unlock 2 Write 1 */
        jsf_outl(p, 0x55555555);                /* Unlock 2 Write 2 */
        jsf_outl(p, 0x10101010);                /* Chip erase */

#if 0
        /*
         * This code is ok, except that counter based timeout
         * has no place in this world. Let's just drop timeouts...
         */
        {
                int i;
                __u32 x;
                for (i = 0; i < 1000000; i++) {
                        x = jsf_inl(p);
                        if ((x & 0x80808080) == 0x80808080) break;
                }
                if ((x & 0x80808080) != 0x80808080) {
                        printk("jsf0: erase timeout with 0x%08x\n", x);
                } else {
                        printk("jsf0: erase done with 0x%08x\n", x);
                }
        }
#else
        jsf_wait(p);
#endif

        return 0;
}

/*
 * Program a block of flash.
 * Very simple because we can do it byte by byte anyway.
 */
static int jsf_ioctl_program(void __user *arg)
{
        struct jsflash_program_arg abuf;
        char __user *uptr;
        unsigned long p;
        unsigned int togo;
        union {
                unsigned int n;
                char s[4];
        } b;

        if (copy_from_user(&abuf, arg, JSFPRGSZ))
                return -EFAULT; 
        p = abuf.off;
        togo = abuf.size;
        if ((togo & 3) || (p & 3)) return -EINVAL;

        uptr = (char __user *) (unsigned long) abuf.data;
        while (togo != 0) {
                togo -= 4;
                if (copy_from_user(&b.s[0], uptr, 4))
                        return -EFAULT;
                jsf_write4(p, b.n);
                p += 4;
                uptr += 4;
        }

        return 0;
}

static long jsf_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
{
        mutex_lock(&jsf_mutex);
        int error = -ENOTTY;
        void __user *argp = (void __user *)arg;

        if (!capable(CAP_SYS_ADMIN)) {
                mutex_unlock(&jsf_mutex);
                return -EPERM;
        }
        switch (cmd) {
        case JSFLASH_IDENT:
                if (copy_to_user(argp, &jsf0.id, JSFIDSZ)) {
                        mutex_unlock(&jsf_mutex);
                        return -EFAULT;
                }
                break;
        case JSFLASH_ERASE:
                error = jsf_ioctl_erase(arg);
                break;
        case JSFLASH_PROGRAM:
                error = jsf_ioctl_program(argp);
                break;
        }

        mutex_unlock(&jsf_mutex);
        return error;
}

static int jsf_mmap(struct file * file, struct vm_area_struct * vma)
{
        return -ENXIO;
}

static int jsf_open(struct inode * inode, struct file * filp)
{
        mutex_lock(&jsf_mutex);
        if (jsf0.base == 0) {
                mutex_unlock(&jsf_mutex);
                return -ENXIO;
        }
        if (test_and_set_bit(0, (void *)&jsf0.busy) != 0) {
                mutex_unlock(&jsf_mutex);
                return -EBUSY;
        }

        mutex_unlock(&jsf_mutex);
        return 0;       /* XXX What security? */
}

static int jsf_release(struct inode *inode, struct file *file)
{
        jsf0.busy = 0;
        return 0;
}

static const struct file_operations jsf_fops = {
        .owner =        THIS_MODULE,
        .llseek =       jsf_lseek,
        .read =         jsf_read,
        .write =        jsf_write,
        .unlocked_ioctl =       jsf_ioctl,
        .mmap =         jsf_mmap,
        .open =         jsf_open,
        .release =      jsf_release,
};

static struct miscdevice jsf_dev = { JSF_MINOR, "jsflash", &jsf_fops };

static const struct block_device_operations jsfd_fops = {
        .owner =        THIS_MODULE,
};

static int jsflash_init(void)
{
        int rc;
        struct jsflash *jsf;
        phandle node;
        char banner[128];
        struct linux_prom_registers reg0;

        node = prom_getchild(prom_root_node);
        node = prom_searchsiblings(node, "flash-memory");
        if (node != 0 && (s32)node != -1) {
                if (prom_getproperty(node, "reg",
                    (char *)&reg0, sizeof(reg0)) == -1) {
                        printk("jsflash: no \"reg\" property\n");
                        return -ENXIO;
                }
                if (reg0.which_io != 0) {
                        printk("jsflash: bus number nonzero: 0x%x:%x\n",
                            reg0.which_io, reg0.phys_addr);
                        return -ENXIO;
                }
                /*
                 * Flash may be somewhere else, for instance on Ebus.
                 * So, don't do the following check for IIep flash space.
                 */
#if 0
                if ((reg0.phys_addr >> 24) != 0x20) {
                        printk("jsflash: suspicious address: 0x%x:%x\n",
                            reg0.which_io, reg0.phys_addr);
                        return -ENXIO;
                }
#endif
                if ((int)reg0.reg_size <= 0) {
                        printk("jsflash: bad size 0x%x\n", (int)reg0.reg_size);
                        return -ENXIO;
                }
        } else {
                /* XXX Remove this code once PROLL ID12 got widespread */
                printk("jsflash: no /flash-memory node, use PROLL >= 12\n");
                prom_getproperty(prom_root_node, "banner-name", banner, 128);
                if (strcmp (banner, "JavaStation-NC") != 0 &&
                    strcmp (banner, "JavaStation-E") != 0) {
                        return -ENXIO;
                }
                reg0.which_io = 0;
                reg0.phys_addr = 0x20400000;
                reg0.reg_size  = 0x00800000;
        }

        /* Let us be really paranoid for modifications to probing code. */
        /* extern enum sparc_cpu sparc_cpu_model; */ /* in <asm/system.h> */
        if (sparc_cpu_model != sun4m) {
                /* We must be on sun4m because we use MMU Bypass ASI. */
                return -ENXIO;
        }

        if (jsf0.base == 0) {
                jsf = &jsf0;

                jsf->base = reg0.phys_addr;
                jsf->size = reg0.reg_size;

                /* XXX Redo the userland interface. */
                jsf->id.off = JSF_BASE_ALL;
                jsf->id.size = 0x01000000;      /* 16M - all segments */
                strcpy(jsf->id.name, "Krups_all");

                jsf->dv[0].dbase = jsf->base;
                jsf->dv[0].dsize = jsf->size;
                jsf->dv[1].dbase = jsf->base + 1024;
                jsf->dv[1].dsize = jsf->size - 1024;
                jsf->dv[2].dbase = JSF_BASE_ALL;
                jsf->dv[2].dsize = 0x01000000;

                printk("Espresso Flash @0x%lx [%d MB]\n", jsf->base,
                    (int) (jsf->size / (1024*1024)));
        }

        if ((rc = misc_register(&jsf_dev)) != 0) {
                printk(KERN_ERR "jsf: unable to get misc minor %d\n",
                    JSF_MINOR);
                jsf0.base = 0;
                return rc;
        }

        return 0;
}

static struct request_queue *jsf_queue;

static int jsfd_init(void)
{
        static DEFINE_SPINLOCK(lock);
        struct jsflash *jsf;
        struct jsfd_part *jdp;
        int err;
        int i;

        if (jsf0.base == 0)
                return -ENXIO;

        err = -ENOMEM;
        for (i = 0; i < JSF_MAX; i++) {
                struct gendisk *disk = alloc_disk(1);
                if (!disk)
                        goto out;
                jsfd_disk[i] = disk;
        }

        if (register_blkdev(JSFD_MAJOR, "jsfd")) {
                err = -EIO;
                goto out;
        }

        jsf_queue = blk_init_queue(jsfd_do_request, &lock);
        if (!jsf_queue) {
                err = -ENOMEM;
                unregister_blkdev(JSFD_MAJOR, "jsfd");
                goto out;
        }

        for (i = 0; i < JSF_MAX; i++) {
                struct gendisk *disk = jsfd_disk[i];
                if ((i & JSF_PART_MASK) >= JSF_NPART) continue;
                jsf = &jsf0;    /* actually, &jsfv[i >> JSF_PART_BITS] */
                jdp = &jsf->dv[i&JSF_PART_MASK];

                disk->major = JSFD_MAJOR;
                disk->first_minor = i;
                sprintf(disk->disk_name, "jsfd%d", i);
                disk->fops = &jsfd_fops;
                set_capacity(disk, jdp->dsize >> 9);
                disk->private_data = jdp;
                disk->queue = jsf_queue;
                add_disk(disk);
                set_disk_ro(disk, 1);
        }
        return 0;
out:
        while (i--)
                put_disk(jsfd_disk[i]);
        return err;
}

MODULE_LICENSE("GPL");

static int __init jsflash_init_module(void) {
        int rc;

        if ((rc = jsflash_init()) == 0) {
                jsfd_init();
                return 0;
        }
        return rc;
}

static void __exit jsflash_cleanup_module(void)
{
        int i;

        for (i = 0; i < JSF_MAX; i++) {
                if ((i & JSF_PART_MASK) >= JSF_NPART) continue;
                del_gendisk(jsfd_disk[i]);
                put_disk(jsfd_disk[i]);
        }
        if (jsf0.busy)
                printk("jsf0: cleaning busy unit\n");
        jsf0.base = 0;
        jsf0.busy = 0;

        misc_deregister(&jsf_dev);
        unregister_blkdev(JSFD_MAJOR, "jsfd");
        blk_cleanup_queue(jsf_queue);
}

module_init(jsflash_init_module);
module_exit(jsflash_cleanup_module);