// SPDX-License-Identifier: GPL-2.0+
/*
 * IBM RTAS driver interface to hvc_console.c
 *
 * (C) Copyright IBM Corporation 2001-2005
 * (C) Copyright Red Hat, Inc. 2005
 *
 * Author(s): Maximino Augilar <IBM STI Design Center>
 *          : Ryan S. Arnold <rsa@us.ibm.com>
 *          : Utz Bacher <utz.bacher@de.ibm.com>
 *          : David Woodhouse <dwmw2@infradead.org>
 *
 *    inspired by drivers/char/hvc_console.c
 *    written by Anton Blanchard and Paul Mackerras
 */

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

#include <asm/irq.h>
#include <asm/rtas.h>
#include "hvc_console.h"

#define hvc_rtas_cookie 0x67781e15
static struct hvc_struct *hvc_rtas_dev;

static int rtascons_put_char_token = RTAS_UNKNOWN_SERVICE;
static int rtascons_get_char_token = RTAS_UNKNOWN_SERVICE;

static ssize_t hvc_rtas_write_console(uint32_t vtermno, const u8 *buf,
                                      size_t count)
{
        size_t i;

        for (i = 0; i < count; i++) {
                if (rtas_call(rtascons_put_char_token, 1, 1, NULL, buf[i]))
                        break;
        }

        return i;
}

static ssize_t hvc_rtas_read_console(uint32_t vtermno, u8 *buf, size_t count)
{
        size_t i;
        int c;

        for (i = 0; i < count; i++) {
                if (rtas_call(rtascons_get_char_token, 0, 2, &c))
                        break;

                buf[i] = c;
        }

        return i;
}

static const struct hv_ops hvc_rtas_get_put_ops = {
        .get_chars = hvc_rtas_read_console,
        .put_chars = hvc_rtas_write_console,
};

static int __init hvc_rtas_init(void)
{
        struct hvc_struct *hp;

        if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
                rtascons_put_char_token = rtas_token("put-term-char");
        if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
                return -EIO;

        if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
                rtascons_get_char_token = rtas_token("get-term-char");
        if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
                return -EIO;

        BUG_ON(hvc_rtas_dev);

        /* Allocate an hvc_struct for the console device we instantiated
         * earlier.  Save off hp so that we can return it on exit */
        hp = hvc_alloc(hvc_rtas_cookie, 0, &hvc_rtas_get_put_ops, 16);
        if (IS_ERR(hp))
                return PTR_ERR(hp);

        hvc_rtas_dev = hp;

        return 0;
}
device_initcall(hvc_rtas_init);

/* This will happen prior to module init.  There is no tty at this time? */
static int __init hvc_rtas_console_init(void)
{
        rtascons_put_char_token = rtas_token("put-term-char");
        if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
                return -EIO;

        rtascons_get_char_token = rtas_token("get-term-char");
        if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
                return -EIO;

        hvc_instantiate(hvc_rtas_cookie, 0, &hvc_rtas_get_put_ops);
        add_preferred_console("hvc", 0, NULL);

        return 0;
}
console_initcall(hvc_rtas_console_init);