/*
 * xen console driver interface to hvc_console.c
 *
 * (c) 2007 Gerd Hoffmann <kraxel@suse.de>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/console.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/types.h>

#include <asm/xen/hypervisor.h>

#include <xen/xen.h>
#include <xen/page.h>
#include <xen/events.h>
#include <xen/interface/io/console.h>
#include <xen/hvc-console.h>

#include "hvc_console.h"

#define HVC_COOKIE   0x58656e /* "Xen" in hex */

static struct hvc_struct *hvc;
static int xencons_irq;

/* ------------------------------------------------------------------ */

static unsigned long console_pfn = ~0ul;

static inline struct xencons_interface *xencons_interface(void)
{
        if (console_pfn == ~0ul)
                return mfn_to_virt(xen_start_info->console.domU.mfn);
        else
                return __va(console_pfn << PAGE_SHIFT);
}

static inline void notify_daemon(void)
{
        /* Use evtchn: this is called early, before irq is set up. */
        notify_remote_via_evtchn(xen_start_info->console.domU.evtchn);
}

static int __write_console(const char *data, int len)
{
        struct xencons_interface *intf = xencons_interface();
        XENCONS_RING_IDX cons, prod;
        int sent = 0;

        cons = intf->out_cons;
        prod = intf->out_prod;
        mb();                   /* update queue values before going on */
        BUG_ON((prod - cons) > sizeof(intf->out));

        while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
                intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];

        wmb();                  /* write ring before updating pointer */
        intf->out_prod = prod;

        if (sent)
                notify_daemon();
        return sent;
}

static int domU_write_console(uint32_t vtermno, const char *data, int len)
{
        int ret = len;

        /*
         * Make sure the whole buffer is emitted, polling if
         * necessary.  We don't ever want to rely on the hvc daemon
         * because the most interesting console output is when the
         * kernel is crippled.
         */
        while (len) {
                int sent = __write_console(data, len);
                
                data += sent;
                len -= sent;

                if (unlikely(len))
                        HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
        }

        return ret;
}

static int domU_read_console(uint32_t vtermno, char *buf, int len)
{
        struct xencons_interface *intf = xencons_interface();
        XENCONS_RING_IDX cons, prod;
        int recv = 0;

        cons = intf->in_cons;
        prod = intf->in_prod;
        mb();                   /* get pointers before reading ring */
        BUG_ON((prod - cons) > sizeof(intf->in));

        while (cons != prod && recv < len)
                buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];

        mb();                   /* read ring before consuming */
        intf->in_cons = cons;

        notify_daemon();
        return recv;
}

static struct hv_ops domU_hvc_ops = {
        .get_chars = domU_read_console,
        .put_chars = domU_write_console,
        .notifier_add = notifier_add_irq,
        .notifier_del = notifier_del_irq,
        .notifier_hangup = notifier_hangup_irq,
};

static int dom0_read_console(uint32_t vtermno, char *buf, int len)
{
        return HYPERVISOR_console_io(CONSOLEIO_read, len, buf);
}

/*
 * Either for a dom0 to write to the system console, or a domU with a
 * debug version of Xen
 */
static int dom0_write_console(uint32_t vtermno, const char *str, int len)
{
        int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
        if (rc < 0)
                return 0;

        return len;
}

static struct hv_ops dom0_hvc_ops = {
        .get_chars = dom0_read_console,
        .put_chars = dom0_write_console,
        .notifier_add = notifier_add_irq,
        .notifier_del = notifier_del_irq,
        .notifier_hangup = notifier_hangup_irq,
};

static int __init xen_hvc_init(void)
{
        struct hvc_struct *hp;
        struct hv_ops *ops;

        if (!xen_pv_domain())
                return -ENODEV;

        if (xen_initial_domain()) {
                ops = &dom0_hvc_ops;
                xencons_irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
        } else {
                if (!xen_start_info->console.domU.evtchn)
                        return -ENODEV;

                ops = &domU_hvc_ops;
                xencons_irq = bind_evtchn_to_irq(xen_start_info->console.domU.evtchn);
        }
        if (xencons_irq < 0)
                xencons_irq = 0; /* NO_IRQ */

        hp = hvc_alloc(HVC_COOKIE, xencons_irq, ops, 256);
        if (IS_ERR(hp))
                return PTR_ERR(hp);

        hvc = hp;

        console_pfn = mfn_to_pfn(xen_start_info->console.domU.mfn);

        return 0;
}

void xen_console_resume(void)
{
        if (xencons_irq)
                rebind_evtchn_irq(xen_start_info->console.domU.evtchn, xencons_irq);
}

static void __exit xen_hvc_fini(void)
{
        if (hvc)
                hvc_remove(hvc);
}

static int xen_cons_init(void)
{
        struct hv_ops *ops;

        if (!xen_pv_domain())
                return 0;

        if (xen_initial_domain())
                ops = &dom0_hvc_ops;
        else
                ops = &domU_hvc_ops;

        hvc_instantiate(HVC_COOKIE, 0, ops);
        return 0;
}

module_init(xen_hvc_init);
module_exit(xen_hvc_fini);
console_initcall(xen_cons_init);

#ifdef CONFIG_EARLY_PRINTK
static void xenboot_write_console(struct console *console, const char *string,
                                  unsigned len)
{
        unsigned int linelen, off = 0;
        const char *pos;

        dom0_write_console(0, string, len);

        if (xen_initial_domain())
                return;

        domU_write_console(0, "(early) ", 8);
        while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
                linelen = pos-string+off;
                if (off + linelen > len)
                        break;
                domU_write_console(0, string+off, linelen);
                domU_write_console(0, "\r\n", 2);
                off += linelen + 1;
        }
        if (off < len)
                domU_write_console(0, string+off, len-off);
}

struct console xenboot_console = {
        .name           = "xenboot",
        .write          = xenboot_write_console,
        .flags          = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
};
#endif  /* CONFIG_EARLY_PRINTK */

void xen_raw_console_write(const char *str)
{
        dom0_write_console(0, str, strlen(str));
}

void xen_raw_printk(const char *fmt, ...)
{
        static char buf[512];
        va_list ap;

        va_start(ap, fmt);
        vsnprintf(buf, sizeof(buf), fmt, ap);
        va_end(ap);

        xen_raw_console_write(buf);
}