// SPDX-License-Identifier: GPL-2.0-or-later
/* 
 *    PDC Console support - ie use firmware to dump text via boot console
 *
 *    Copyright (C) 1999-2003 Matthew Wilcox <willy at parisc-linux.org>
 *    Copyright (C) 2000 Martin K Petersen <mkp at mkp.net>
 *    Copyright (C) 2000 John Marvin <jsm at parisc-linux.org>
 *    Copyright (C) 2000-2003 Paul Bame <bame at parisc-linux.org>
 *    Copyright (C) 2000 Philipp Rumpf <prumpf with tux.org>
 *    Copyright (C) 2000 Michael Ang <mang with subcarrier.org>
 *    Copyright (C) 2000 Grant Grundler <grundler with parisc-linux.org>
 *    Copyright (C) 2001-2002 Ryan Bradetich <rbrad at parisc-linux.org>
 *    Copyright (C) 2001 Helge Deller <deller at parisc-linux.org>
 *    Copyright (C) 2001 Thomas Bogendoerfer <tsbogend at parisc-linux.org>
 *    Copyright (C) 2002 Randolph Chung <tausq with parisc-linux.org>
 *    Copyright (C) 2010 Guy Martin <gmsoft at tuxicoman.be>
 */

/*
 *  The PDC console is a simple console, which can be used for debugging 
 *  boot related problems on HP PA-RISC machines. It is also useful when no
 *  other console works.
 *
 *  This code uses the ROM (=PDC) based functions to read and write characters
 *  from and to PDC's boot path.
 */

/* Define EARLY_BOOTUP_DEBUG to debug kernel related boot problems. 
 * On production kernels EARLY_BOOTUP_DEBUG should be undefined. */
#define EARLY_BOOTUP_DEBUG


#include <linux/kernel.h>
#include <linux/console.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/major.h>
#include <linux/tty.h>
#include <asm/page.h>           /* for PAGE0 */
#include <asm/pdc.h>            /* for iodc_call() proto and friends */

static DEFINE_SPINLOCK(pdc_console_lock);
static struct console pdc_cons;

static void pdc_console_write(struct console *co, const char *s, unsigned count)
{
        int i = 0;
        unsigned long flags;

        spin_lock_irqsave(&pdc_console_lock, flags);
        do {
                i += pdc_iodc_print(s + i, count - i);
        } while (i < count);
        spin_unlock_irqrestore(&pdc_console_lock, flags);
}

int pdc_console_poll_key(struct console *co)
{
        int c;
        unsigned long flags;

        spin_lock_irqsave(&pdc_console_lock, flags);
        c = pdc_iodc_getc();
        spin_unlock_irqrestore(&pdc_console_lock, flags);

        return c;
}

static int pdc_console_setup(struct console *co, char *options)
{
        return 0;
}

#if defined(CONFIG_PDC_CONSOLE)
#include <linux/vt_kern.h>
#include <linux/tty_flip.h>

#define PDC_CONS_POLL_DELAY (30 * HZ / 1000)

static void pdc_console_poll(struct timer_list *unused);
static DEFINE_TIMER(pdc_console_timer, pdc_console_poll);
static struct tty_port tty_port;

static int pdc_console_tty_open(struct tty_struct *tty, struct file *filp)
{
        tty_port_tty_set(&tty_port, tty);
        mod_timer(&pdc_console_timer, jiffies + PDC_CONS_POLL_DELAY);

        return 0;
}

static void pdc_console_tty_close(struct tty_struct *tty, struct file *filp)
{
        if (tty->count == 1) {
                del_timer_sync(&pdc_console_timer);
                tty_port_tty_set(&tty_port, NULL);
        }
}

static int pdc_console_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
        pdc_console_write(NULL, buf, count);
        return count;
}

static int pdc_console_tty_write_room(struct tty_struct *tty)
{
        return 32768; /* no limit, no buffer used */
}

static int pdc_console_tty_chars_in_buffer(struct tty_struct *tty)
{
        return 0; /* no buffer */
}

static const struct tty_operations pdc_console_tty_ops = {
        .open = pdc_console_tty_open,
        .close = pdc_console_tty_close,
        .write = pdc_console_tty_write,
        .write_room = pdc_console_tty_write_room,
        .chars_in_buffer = pdc_console_tty_chars_in_buffer,
};

static void pdc_console_poll(struct timer_list *unused)
{
        int data, count = 0;

        while (1) {
                data = pdc_console_poll_key(NULL);
                if (data == -1)
                        break;
                tty_insert_flip_char(&tty_port, data & 0xFF, TTY_NORMAL);
                count ++;
        }

        if (count)
                tty_flip_buffer_push(&tty_port);

        if (pdc_cons.flags & CON_ENABLED)
                mod_timer(&pdc_console_timer, jiffies + PDC_CONS_POLL_DELAY);
}

static struct tty_driver *pdc_console_tty_driver;

static int __init pdc_console_tty_driver_init(void)
{
        int err;

        /* Check if the console driver is still registered.
         * It is unregistered if the pdc console was not selected as the
         * primary console. */

        struct console *tmp;

        console_lock();
        for_each_console(tmp)
                if (tmp == &pdc_cons)
                        break;
        console_unlock();

        if (!tmp) {
                printk(KERN_INFO "PDC console driver not registered anymore, not creating %s\n", pdc_cons.name);
                return -ENODEV;
        }

        printk(KERN_INFO "The PDC console driver is still registered, removing CON_BOOT flag\n");
        pdc_cons.flags &= ~CON_BOOT;

        pdc_console_tty_driver = alloc_tty_driver(1);

        if (!pdc_console_tty_driver)
                return -ENOMEM;

        tty_port_init(&tty_port);

        pdc_console_tty_driver->driver_name = "pdc_cons";
        pdc_console_tty_driver->name = "ttyB";
        pdc_console_tty_driver->major = MUX_MAJOR;
        pdc_console_tty_driver->minor_start = 0;
        pdc_console_tty_driver->type = TTY_DRIVER_TYPE_SYSTEM;
        pdc_console_tty_driver->init_termios = tty_std_termios;
        pdc_console_tty_driver->flags = TTY_DRIVER_REAL_RAW |
                TTY_DRIVER_RESET_TERMIOS;
        tty_set_operations(pdc_console_tty_driver, &pdc_console_tty_ops);
        tty_port_link_device(&tty_port, pdc_console_tty_driver, 0);

        err = tty_register_driver(pdc_console_tty_driver);
        if (err) {
                printk(KERN_ERR "Unable to register the PDC console TTY driver\n");
                tty_port_destroy(&tty_port);
                return err;
        }

        return 0;
}
device_initcall(pdc_console_tty_driver_init);

static struct tty_driver * pdc_console_device (struct console *c, int *index)
{
        *index = c->index;
        return pdc_console_tty_driver;
}
#else
#define pdc_console_device NULL
#endif

static struct console pdc_cons = {
        .name =         "ttyB",
        .write =        pdc_console_write,
        .device =       pdc_console_device,
        .setup =        pdc_console_setup,
        .flags =        CON_BOOT | CON_PRINTBUFFER,
        .index =        -1,
};

static int pdc_console_initialized;

static void pdc_console_init_force(void)
{
        if (pdc_console_initialized)
                return;
        ++pdc_console_initialized;
        
        /* If the console is duplex then copy the COUT parameters to CIN. */
        if (PAGE0->mem_cons.cl_class == CL_DUPLEX)
                memcpy(&PAGE0->mem_kbd, &PAGE0->mem_cons, sizeof(PAGE0->mem_cons));

        /* register the pdc console */
        register_console(&pdc_cons);
}

void __init pdc_console_init(void)
{
#if defined(EARLY_BOOTUP_DEBUG) || defined(CONFIG_PDC_CONSOLE)
        pdc_console_init_force();
#endif
#ifdef EARLY_BOOTUP_DEBUG
        printk(KERN_INFO "Initialized PDC Console for debugging.\n");
#endif
}


/*
 * Used for emergencies. Currently only used if an HPMC occurs. If an
 * HPMC occurs, it is possible that the current console may not be
 * properly initialised after the PDC IO reset. This routine unregisters
 * all of the current consoles, reinitializes the pdc console and
 * registers it.
 */

void pdc_console_restart(void)
{
        struct console *console;

        if (pdc_console_initialized)
                return;

        /* If we've already seen the output, don't bother to print it again */
        if (console_drivers != NULL)
                pdc_cons.flags &= ~CON_PRINTBUFFER;

        while ((console = console_drivers) != NULL)
                unregister_console(console_drivers);

        /* force registering the pdc console */
        pdc_console_init_force();
}