/*
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include "linux/irqreturn.h"
#include "linux/kd.h"
#include "linux/sched.h"
#include "chan_kern.h"
#include "irq_kern.h"
#include "irq_user.h"
#include "kern_util.h"
#include "os.h"

#define LINE_BUFSIZE 4096

static irqreturn_t line_interrupt(int irq, void *data)
{
        struct chan *chan = data;
        struct line *line = chan->line;
        struct tty_struct *tty = line->tty;

        if (line)
                chan_interrupt(&line->chan_list, &line->task, tty, irq);
        return IRQ_HANDLED;
}

static void line_timer_cb(struct work_struct *work)
{
        struct line *line = container_of(work, struct line, task.work);

        if (!line->throttled)
                chan_interrupt(&line->chan_list, &line->task, line->tty,
                               line->driver->read_irq);
}

/*
 * Returns the free space inside the ring buffer of this line.
 *
 * Should be called while holding line->lock (this does not modify data).
 */
static int write_room(struct line *line)
{
        int n;

        if (line->buffer == NULL)
                return LINE_BUFSIZE - 1;

        /* This is for the case where the buffer is wrapped! */
        n = line->head - line->tail;

        if (n <= 0)
                n += LINE_BUFSIZE; /* The other case */
        return n - 1;
}

int line_write_room(struct tty_struct *tty)
{
        struct line *line = tty->driver_data;
        unsigned long flags;
        int room;

        spin_lock_irqsave(&line->lock, flags);
        room = write_room(line);
        spin_unlock_irqrestore(&line->lock, flags);

        return room;
}

int line_chars_in_buffer(struct tty_struct *tty)
{
        struct line *line = tty->driver_data;
        unsigned long flags;
        int ret;

        spin_lock_irqsave(&line->lock, flags);
        /* write_room subtracts 1 for the needed NULL, so we readd it.*/
        ret = LINE_BUFSIZE - (write_room(line) + 1);
        spin_unlock_irqrestore(&line->lock, flags);

        return ret;
}

/*
 * This copies the content of buf into the circular buffer associated with
 * this line.
 * The return value is the number of characters actually copied, i.e. the ones
 * for which there was space: this function is not supposed to ever flush out
 * the circular buffer.
 *
 * Must be called while holding line->lock!
 */
static int buffer_data(struct line *line, const char *buf, int len)
{
        int end, room;

        if (line->buffer == NULL) {
                line->buffer = kmalloc(LINE_BUFSIZE, GFP_ATOMIC);
                if (line->buffer == NULL) {
                        printk(KERN_ERR "buffer_data - atomic allocation "
                               "failed\n");
                        return 0;
                }
                line->head = line->buffer;
                line->tail = line->buffer;
        }

        room = write_room(line);
        len = (len > room) ? room : len;

        end = line->buffer + LINE_BUFSIZE - line->tail;

        if (len < end) {
                memcpy(line->tail, buf, len);
                line->tail += len;
        }
        else {
                /* The circular buffer is wrapping */
                memcpy(line->tail, buf, end);
                buf += end;
                memcpy(line->buffer, buf, len - end);
                line->tail = line->buffer + len - end;
        }

        return len;
}

/*
 * Flushes the ring buffer to the output channels. That is, write_chan is
 * called, passing it line->head as buffer, and an appropriate count.
 *
 * On exit, returns 1 when the buffer is empty,
 * 0 when the buffer is not empty on exit,
 * and -errno when an error occurred.
 *
 * Must be called while holding line->lock!*/
static int flush_buffer(struct line *line)
{
        int n, count;

        if ((line->buffer == NULL) || (line->head == line->tail))
                return 1;

        if (line->tail < line->head) {
                /* line->buffer + LINE_BUFSIZE is the end of the buffer! */
                count = line->buffer + LINE_BUFSIZE - line->head;

                n = write_chan(&line->chan_list, line->head, count,
                               line->driver->write_irq);
                if (n < 0)
                        return n;
                if (n == count) {
                        /*
                         * We have flushed from ->head to buffer end, now we
                         * must flush only from the beginning to ->tail.
                         */
                        line->head = line->buffer;
                } else {
                        line->head += n;
                        return 0;
                }
        }

        count = line->tail - line->head;
        n = write_chan(&line->chan_list, line->head, count,
                       line->driver->write_irq);

        if (n < 0)
                return n;

        line->head += n;
        return line->head == line->tail;
}

void line_flush_buffer(struct tty_struct *tty)
{
        struct line *line = tty->driver_data;
        unsigned long flags;
        int err;

        spin_lock_irqsave(&line->lock, flags);
        err = flush_buffer(line);
        spin_unlock_irqrestore(&line->lock, flags);
}

/*
 * We map both ->flush_chars and ->put_char (which go in pair) onto
 * ->flush_buffer and ->write. Hope it's not that bad.
 */
void line_flush_chars(struct tty_struct *tty)
{
        line_flush_buffer(tty);
}

int line_put_char(struct tty_struct *tty, unsigned char ch)
{
        return line_write(tty, &ch, sizeof(ch));
}

int line_write(struct tty_struct *tty, const unsigned char *buf, int len)
{
        struct line *line = tty->driver_data;
        unsigned long flags;
        int n, ret = 0;

        spin_lock_irqsave(&line->lock, flags);
        if (line->head != line->tail)
                ret = buffer_data(line, buf, len);
        else {
                n = write_chan(&line->chan_list, buf, len,
                               line->driver->write_irq);
                if (n < 0) {
                        ret = n;
                        goto out_up;
                }

                len -= n;
                ret += n;
                if (len > 0)
                        ret += buffer_data(line, buf + n, len);
        }
out_up:
        spin_unlock_irqrestore(&line->lock, flags);
        return ret;
}

void line_set_termios(struct tty_struct *tty, struct ktermios * old)
{
        /* nothing */
}

static const struct {
        int  cmd;
        char *level;
        char *name;
} tty_ioctls[] = {
        /* don't print these, they flood the log ... */
        { TCGETS,      NULL,       "TCGETS"      },
        { TCSETS,      NULL,       "TCSETS"      },
        { TCSETSW,     NULL,       "TCSETSW"     },
        { TCFLSH,      NULL,       "TCFLSH"      },
        { TCSBRK,      NULL,       "TCSBRK"      },

        /* general tty stuff */
        { TCSETSF,     KERN_DEBUG, "TCSETSF"     },
        { TCGETA,      KERN_DEBUG, "TCGETA"      },
        { TIOCMGET,    KERN_DEBUG, "TIOCMGET"    },
        { TCSBRKP,     KERN_DEBUG, "TCSBRKP"     },
        { TIOCMSET,    KERN_DEBUG, "TIOCMSET"    },

        /* linux-specific ones */
        { TIOCLINUX,   KERN_INFO,  "TIOCLINUX"   },
        { KDGKBMODE,   KERN_INFO,  "KDGKBMODE"   },
        { KDGKBTYPE,   KERN_INFO,  "KDGKBTYPE"   },
        { KDSIGACCEPT, KERN_INFO,  "KDSIGACCEPT" },
};

int line_ioctl(struct tty_struct *tty, struct file * file,
               unsigned int cmd, unsigned long arg)
{
        int ret;
        int i;

        ret = 0;
        switch(cmd) {
#ifdef TIOCGETP
        case TIOCGETP:
        case TIOCSETP:
        case TIOCSETN:
#endif
#ifdef TIOCGETC
        case TIOCGETC:
        case TIOCSETC:
#endif
#ifdef TIOCGLTC
        case TIOCGLTC:
        case TIOCSLTC:
#endif
        /* Note: these are out of date as we now have TCGETS2 etc but this
           whole lot should probably go away */
        case TCGETS:
        case TCSETSF:
        case TCSETSW:
        case TCSETS:
        case TCGETA:
        case TCSETAF:
        case TCSETAW:
        case TCSETA:
        case TCXONC:
        case TCFLSH:
        case TIOCOUTQ:
        case TIOCINQ:
        case TIOCGLCKTRMIOS:
        case TIOCSLCKTRMIOS:
        case TIOCPKT:
        case TIOCGSOFTCAR:
        case TIOCSSOFTCAR:
                return -ENOIOCTLCMD;
#if 0
        case TCwhatever:
                /* do something */
                break;
#endif
        default:
                for (i = 0; i < ARRAY_SIZE(tty_ioctls); i++)
                        if (cmd == tty_ioctls[i].cmd)
                                break;
                if (i == ARRAY_SIZE(tty_ioctls)) {
                        printk(KERN_ERR "%s: %s: unknown ioctl: 0x%x\n",
                               __func__, tty->name, cmd);
                }
                ret = -ENOIOCTLCMD;
                break;
        }
        return ret;
}

void line_throttle(struct tty_struct *tty)
{
        struct line *line = tty->driver_data;

        deactivate_chan(&line->chan_list, line->driver->read_irq);
        line->throttled = 1;
}

void line_unthrottle(struct tty_struct *tty)
{
        struct line *line = tty->driver_data;

        line->throttled = 0;
        chan_interrupt(&line->chan_list, &line->task, tty,
                       line->driver->read_irq);

        /*
         * Maybe there is enough stuff pending that calling the interrupt
         * throttles us again.  In this case, line->throttled will be 1
         * again and we shouldn't turn the interrupt back on.
         */
        if (!line->throttled)
                reactivate_chan(&line->chan_list, line->driver->read_irq);
}

static irqreturn_t line_write_interrupt(int irq, void *data)
{
        struct chan *chan = data;
        struct line *line = chan->line;
        struct tty_struct *tty = line->tty;
        int err;

        /*
         * Interrupts are disabled here because we registered the interrupt with
         * IRQF_DISABLED (see line_setup_irq).
         */

        spin_lock(&line->lock);
        err = flush_buffer(line);
        if (err == 0) {
                return IRQ_NONE;
        } else if (err < 0) {
                line->head = line->buffer;
                line->tail = line->buffer;
        }
        spin_unlock(&line->lock);

        if (tty == NULL)
                return IRQ_NONE;

        tty_wakeup(tty);
        return IRQ_HANDLED;
}

int line_setup_irq(int fd, int input, int output, struct line *line, void *data)
{
        const struct line_driver *driver = line->driver;
        int err = 0, flags = IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM;

        if (input)
                err = um_request_irq(driver->read_irq, fd, IRQ_READ,
                                       line_interrupt, flags,
                                       driver->read_irq_name, data);
        if (err)
                return err;
        if (output)
                err = um_request_irq(driver->write_irq, fd, IRQ_WRITE,
                                        line_write_interrupt, flags,
                                        driver->write_irq_name, data);
        line->have_irq = 1;
        return err;
}

/*
 * Normally, a driver like this can rely mostly on the tty layer
 * locking, particularly when it comes to the driver structure.
 * However, in this case, mconsole requests can come in "from the
 * side", and race with opens and closes.
 *
 * mconsole config requests will want to be sure the device isn't in
 * use, and get_config, open, and close will want a stable
 * configuration.  The checking and modification of the configuration
 * is done under a spinlock.  Checking whether the device is in use is
 * line->tty->count > 1, also under the spinlock.
 *
 * tty->count serves to decide whether the device should be enabled or
 * disabled on the host.  If it's equal to 1, then we are doing the
 * first open or last close.  Otherwise, open and close just return.
 */

int line_open(struct line *lines, struct tty_struct *tty)
{
        struct line *line = &lines[tty->index];
        int err = -ENODEV;

        spin_lock(&line->count_lock);
        if (!line->valid)
                goto out_unlock;

        err = 0;
        if (tty->count > 1)
                goto out_unlock;

        spin_unlock(&line->count_lock);

        tty->driver_data = line;
        line->tty = tty;

        err = enable_chan(line);
        if (err)
                return err;

        INIT_DELAYED_WORK(&line->task, line_timer_cb);

        if (!line->sigio) {
                chan_enable_winch(&line->chan_list, tty);
                line->sigio = 1;
        }

        chan_window_size(&line->chan_list, &tty->winsize.ws_row,
                         &tty->winsize.ws_col);

        return err;

out_unlock:
        spin_unlock(&line->count_lock);
        return err;
}

static void unregister_winch(struct tty_struct *tty);

void line_close(struct tty_struct *tty, struct file * filp)
{
        struct line *line = tty->driver_data;

        /*
         * If line_open fails (and tty->driver_data is never set),
         * tty_open will call line_close.  So just return in this case.
         */
        if (line == NULL)
                return;

        /* We ignore the error anyway! */
        flush_buffer(line);

        spin_lock(&line->count_lock);
        if (!line->valid)
                goto out_unlock;

        if (tty->count > 1)
                goto out_unlock;

        spin_unlock(&line->count_lock);

        line->tty = NULL;
        tty->driver_data = NULL;

        if (line->sigio) {
                unregister_winch(tty);
                line->sigio = 0;
        }

        return;

out_unlock:
        spin_unlock(&line->count_lock);
}

void close_lines(struct line *lines, int nlines)
{
        int i;

        for(i = 0; i < nlines; i++)
                close_chan(&lines[i].chan_list, 0);
}

static int setup_one_line(struct line *lines, int n, char *init, int init_prio,
                          char **error_out)
{
        struct line *line = &lines[n];
        int err = -EINVAL;

        spin_lock(&line->count_lock);

        if (line->tty != NULL) {
                *error_out = "Device is already open";
                goto out;
        }

        if (line->init_pri <= init_prio) {
                line->init_pri = init_prio;
                if (!strcmp(init, "none"))
                        line->valid = 0;
                else {
                        line->init_str = init;
                        line->valid = 1;
                }
        }
        err = 0;
out:
        spin_unlock(&line->count_lock);
        return err;
}

/*
 * Common setup code for both startup command line and mconsole initialization.
 * @lines contains the array (of size @num) to modify;
 * @init is the setup string;
 * @error_out is an error string in the case of failure;
 */

int line_setup(struct line *lines, unsigned int num, char *init,
               char **error_out)
{
        int i, n, err;
        char *end;

        if (*init == '=') {
                /*
                 * We said con=/ssl= instead of con#=, so we are configuring all
                 * consoles at once.
                 */
                n = -1;
        }
        else {
                n = simple_strtoul(init, &end, 0);
                if (*end != '=') {
                        *error_out = "Couldn't parse device number";
                        return -EINVAL;
                }
                init = end;
        }
        init++;

        if (n >= (signed int) num) {
                *error_out = "Device number out of range";
                return -EINVAL;
        }
        else if (n >= 0) {
                err = setup_one_line(lines, n, init, INIT_ONE, error_out);
                if (err)
                        return err;
        }
        else {
                for(i = 0; i < num; i++) {
                        err = setup_one_line(lines, i, init, INIT_ALL,
                                             error_out);
                        if (err)
                                return err;
                }
        }
        return n == -1 ? num : n;
}

int line_config(struct line *lines, unsigned int num, char *str,
                const struct chan_opts *opts, char **error_out)
{
        struct line *line;
        char *new;
        int n;

        if (*str == '=') {
                *error_out = "Can't configure all devices from mconsole";
                return -EINVAL;
        }

        new = kstrdup(str, GFP_KERNEL);
        if (new == NULL) {
                *error_out = "Failed to allocate memory";
                return -ENOMEM;
        }
        n = line_setup(lines, num, new, error_out);
        if (n < 0)
                return n;

        line = &lines[n];
        return parse_chan_pair(line->init_str, line, n, opts, error_out);
}

int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
                    int size, char **error_out)
{
        struct line *line;
        char *end;
        int dev, n = 0;

        dev = simple_strtoul(name, &end, 0);
        if ((*end != '\0') || (end == name)) {
                *error_out = "line_get_config failed to parse device number";
                return 0;
        }

        if ((dev < 0) || (dev >= num)) {
                *error_out = "device number out of range";
                return 0;
        }

        line = &lines[dev];

        spin_lock(&line->count_lock);
        if (!line->valid)
                CONFIG_CHUNK(str, size, n, "none", 1);
        else if (line->tty == NULL)
                CONFIG_CHUNK(str, size, n, line->init_str, 1);
        else n = chan_config_string(&line->chan_list, str, size, error_out);
        spin_unlock(&line->count_lock);

        return n;
}

int line_id(char **str, int *start_out, int *end_out)
{
        char *end;
        int n;

        n = simple_strtoul(*str, &end, 0);
        if ((*end != '\0') || (end == *str))
                return -1;

        *str = end;
        *start_out = n;
        *end_out = n;
        return n;
}

int line_remove(struct line *lines, unsigned int num, int n, char **error_out)
{
        int err;
        char config[sizeof("conxxxx=none\0")];

        sprintf(config, "%d=none", n);
        err = line_setup(lines, num, config, error_out);
        if (err >= 0)
                err = 0;
        return err;
}

struct tty_driver *register_lines(struct line_driver *line_driver,
                                  const struct tty_operations *ops,
                                  struct line *lines, int nlines)
{
        int i;
        struct tty_driver *driver = alloc_tty_driver(nlines);

        if (!driver)
                return NULL;

        driver->driver_name = line_driver->name;
        driver->name = line_driver->device_name;
        driver->major = line_driver->major;
        driver->minor_start = line_driver->minor_start;
        driver->type = line_driver->type;
        driver->subtype = line_driver->subtype;
        driver->flags = TTY_DRIVER_REAL_RAW;
        driver->init_termios = tty_std_termios;
        tty_set_operations(driver, ops);

        if (tty_register_driver(driver)) {
                printk(KERN_ERR "register_lines : can't register %s driver\n",
                       line_driver->name);
                put_tty_driver(driver);
                return NULL;
        }

        for(i = 0; i < nlines; i++) {
                if (!lines[i].valid)
                        tty_unregister_device(driver, i);
        }

        mconsole_register_dev(&line_driver->mc);
        return driver;
}

static DEFINE_SPINLOCK(winch_handler_lock);
static LIST_HEAD(winch_handlers);

void lines_init(struct line *lines, int nlines, struct chan_opts *opts)
{
        struct line *line;
        char *error;
        int i;

        for(i = 0; i < nlines; i++) {
                line = &lines[i];
                INIT_LIST_HEAD(&line->chan_list);

                if (line->init_str == NULL)
                        continue;

                line->init_str = kstrdup(line->init_str, GFP_KERNEL);
                if (line->init_str == NULL)
                        printk(KERN_ERR "lines_init - kstrdup returned NULL\n");

                if (parse_chan_pair(line->init_str, line, i, opts, &error)) {
                        printk(KERN_ERR "parse_chan_pair failed for "
                               "device %d : %s\n", i, error);
                        line->valid = 0;
                }
        }
}

struct winch {
        struct list_head list;
        int fd;
        int tty_fd;
        int pid;
        struct tty_struct *tty;
        unsigned long stack;
};

static void free_winch(struct winch *winch, int free_irq_ok)
{
        list_del(&winch->list);

        if (winch->pid != -1)
                os_kill_process(winch->pid, 1);
        if (winch->fd != -1)
                os_close_file(winch->fd);
        if (winch->stack != 0)
                free_stack(winch->stack, 0);
        if (free_irq_ok)
                free_irq(WINCH_IRQ, winch);
        kfree(winch);
}

static irqreturn_t winch_interrupt(int irq, void *data)
{
        struct winch *winch = data;
        struct tty_struct *tty;
        struct line *line;
        int err;
        char c;

        if (winch->fd != -1) {
                err = generic_read(winch->fd, &c, NULL);
                if (err < 0) {
                        if (err != -EAGAIN) {
                                printk(KERN_ERR "winch_interrupt : "
                                       "read failed, errno = %d\n", -err);
                                printk(KERN_ERR "fd %d is losing SIGWINCH "
                                       "support\n", winch->tty_fd);
                                free_winch(winch, 0);
                                return IRQ_HANDLED;
                        }
                        goto out;
                }
        }
        tty = winch->tty;
        if (tty != NULL) {
                line = tty->driver_data;
                if (line != NULL) {
                        chan_window_size(&line->chan_list, &tty->winsize.ws_row,
                                         &tty->winsize.ws_col);
                        kill_pgrp(tty->pgrp, SIGWINCH, 1);
                }
        }
 out:
        if (winch->fd != -1)
                reactivate_fd(winch->fd, WINCH_IRQ);
        return IRQ_HANDLED;
}

void register_winch_irq(int fd, int tty_fd, int pid, struct tty_struct *tty,
                        unsigned long stack)
{
        struct winch *winch;

        winch = kmalloc(sizeof(*winch), GFP_KERNEL);
        if (winch == NULL) {
                printk(KERN_ERR "register_winch_irq - kmalloc failed\n");
                goto cleanup;
        }

        *winch = ((struct winch) { .list        = LIST_HEAD_INIT(winch->list),
                                   .fd          = fd,
                                   .tty_fd      = tty_fd,
                                   .pid         = pid,
                                   .tty         = tty,
                                   .stack       = stack });

        if (um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
                           IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,
                           "winch", winch) < 0) {
                printk(KERN_ERR "register_winch_irq - failed to register "
                       "IRQ\n");
                goto out_free;
        }

        spin_lock(&winch_handler_lock);
        list_add(&winch->list, &winch_handlers);
        spin_unlock(&winch_handler_lock);

        return;

 out_free:
        kfree(winch);
 cleanup:
        os_kill_process(pid, 1);
        os_close_file(fd);
        if (stack != 0)
                free_stack(stack, 0);
}

static void unregister_winch(struct tty_struct *tty)
{
        struct list_head *ele;
        struct winch *winch;

        spin_lock(&winch_handler_lock);

        list_for_each(ele, &winch_handlers) {
                winch = list_entry(ele, struct winch, list);
                if (winch->tty == tty) {
                        free_winch(winch, 1);
                        break;
                }
        }
        spin_unlock(&winch_handler_lock);
}

static void winch_cleanup(void)
{
        struct list_head *ele, *next;
        struct winch *winch;

        spin_lock(&winch_handler_lock);

        list_for_each_safe(ele, next, &winch_handlers) {
                winch = list_entry(ele, struct winch, list);
                free_winch(winch, 1);
        }

        spin_unlock(&winch_handler_lock);
}
__uml_exitcall(winch_cleanup);

char *add_xterm_umid(char *base)
{
        char *umid, *title;
        int len;

        umid = get_umid();
        if (*umid == '\0')
                return base;

        len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
        title = kmalloc(len, GFP_KERNEL);
        if (title == NULL) {
                printk(KERN_ERR "Failed to allocate buffer for xterm title\n");
                return base;
        }

        snprintf(title, len, "%s (%s)", base, umid);
        return title;
}