/*
 * Copyright (C) 2014 Linaro Ltd.
 * Author: Rob Herring <robh@kernel.org>
 *
 * Based on 8250 earlycon:
 * (c) Copyright 2004 Hewlett-Packard Development Company, L.P.
 *      Bjorn Helgaas <bjorn.helgaas@hp.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt

#include <linux/console.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/serial_core.h>
#include <linux/sizes.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/acpi.h>

#ifdef CONFIG_FIX_EARLYCON_MEM
#include <asm/fixmap.h>
#endif

#include <asm/serial.h>

static struct console early_con = {
        .name =         "uart",         /* fixed up at earlycon registration */
        .flags =        CON_PRINTBUFFER | CON_BOOT,
        .index =        0,
};

static struct earlycon_device early_console_dev = {
        .con = &early_con,
};

static void __iomem * __init earlycon_map(resource_size_t paddr, size_t size)
{
        void __iomem *base;
#ifdef CONFIG_FIX_EARLYCON_MEM
        set_fixmap_io(FIX_EARLYCON_MEM_BASE, paddr & PAGE_MASK);
        base = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);
        base += paddr & ~PAGE_MASK;
#else
        base = ioremap(paddr, size);
#endif
        if (!base)
                pr_err("%s: Couldn't map %pa\n", __func__, &paddr);

        return base;
}

static void __init earlycon_init(struct earlycon_device *device,
                                 const char *name)
{
        struct console *earlycon = device->con;
        struct uart_port *port = &device->port;
        const char *s;
        size_t len;

        /* scan backwards from end of string for first non-numeral */
        for (s = name + strlen(name);
             s > name && s[-1] >= '0' && s[-1] <= '9';
             s--)
                ;
        if (*s)
                earlycon->index = simple_strtoul(s, NULL, 10);
        len = s - name;
        strlcpy(earlycon->name, name, min(len + 1, sizeof(earlycon->name)));
        earlycon->data = &early_console_dev;

        if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM16 ||
            port->iotype == UPIO_MEM32 || port->iotype == UPIO_MEM32BE)
                pr_info("%s%d at MMIO%s %pa (options '%s')\n",
                        earlycon->name, earlycon->index,
                        (port->iotype == UPIO_MEM) ? "" :
                        (port->iotype == UPIO_MEM16) ? "16" :
                        (port->iotype == UPIO_MEM32) ? "32" : "32be",
                        &port->mapbase, device->options);
        else
                pr_info("%s%d at I/O port 0x%lx (options '%s')\n",
                        earlycon->name, earlycon->index,
                        port->iobase, device->options);
}

static int __init parse_options(struct earlycon_device *device, char *options)
{
        struct uart_port *port = &device->port;
        int length;
        resource_size_t addr;

        if (uart_parse_earlycon(options, &port->iotype, &addr, &options))
                return -EINVAL;

        switch (port->iotype) {
        case UPIO_MEM:
                port->mapbase = addr;
                break;
        case UPIO_MEM16:
                port->regshift = 1;
                port->mapbase = addr;
                break;
        case UPIO_MEM32:
        case UPIO_MEM32BE:
                port->regshift = 2;
                port->mapbase = addr;
                break;
        case UPIO_PORT:
                port->iobase = addr;
                break;
        default:
                return -EINVAL;
        }

        if (options) {
                device->baud = simple_strtoul(options, NULL, 0);
                length = min(strcspn(options, " ") + 1,
                             (size_t)(sizeof(device->options)));
                strlcpy(device->options, options, length);
        }

        return 0;
}

static int __init register_earlycon(char *buf, const struct earlycon_id *match)
{
        int err;
        struct uart_port *port = &early_console_dev.port;

        /* On parsing error, pass the options buf to the setup function */
        if (buf && !parse_options(&early_console_dev, buf))
                buf = NULL;

        spin_lock_init(&port->lock);
        port->uartclk = BASE_BAUD * 16;
        if (port->mapbase)
                port->membase = earlycon_map(port->mapbase, 64);

        earlycon_init(&early_console_dev, match->name);
        err = match->setup(&early_console_dev, buf);
        if (err < 0)
                return err;
        if (!early_console_dev.con->write)
                return -ENODEV;

        register_console(early_console_dev.con);
        return 0;
}

/**
 *      setup_earlycon - match and register earlycon console
 *      @buf:   earlycon param string
 *
 *      Registers the earlycon console matching the earlycon specified
 *      in the param string @buf. Acceptable param strings are of the form
 *         <name>,io|mmio|mmio32|mmio32be,<addr>,<options>
 *         <name>,0x<addr>,<options>
 *         <name>,<options>
 *         <name>
 *
 *      Only for the third form does the earlycon setup() method receive the
 *      <options> string in the 'options' parameter; all other forms set
 *      the parameter to NULL.
 *
 *      Returns 0 if an attempt to register the earlycon was made,
 *      otherwise negative error code
 */
int __init setup_earlycon(char *buf)
{
        const struct earlycon_id *match;

        if (!buf || !buf[0])
                return -EINVAL;

        if (early_con.flags & CON_ENABLED)
                return -EALREADY;

        for (match = __earlycon_table; match < __earlycon_table_end; match++) {
                size_t len = strlen(match->name);

                if (strncmp(buf, match->name, len))
                        continue;

                if (buf[len]) {
                        if (buf[len] != ',')
                                continue;
                        buf += len + 1;
                } else
                        buf = NULL;

                return register_earlycon(buf, match);
        }

        return -ENOENT;
}

/*
 * When CONFIG_ACPI_SPCR_TABLE is defined, "earlycon" without parameters in
 * command line does not start DT earlycon immediately, instead it defers
 * starting it until DT/ACPI decision is made.  At that time if ACPI is enabled
 * call parse_spcr(), else call early_init_dt_scan_chosen_stdout()
 */
bool earlycon_init_is_deferred __initdata;

/* early_param wrapper for setup_earlycon() */
static int __init param_setup_earlycon(char *buf)
{
        int err;

        /*
         * Just 'earlycon' is a valid param for devicetree earlycons;
         * don't generate a warning from parse_early_params() in that case
         */
        if (!buf || !buf[0]) {
                if (IS_ENABLED(CONFIG_ACPI_SPCR_TABLE)) {
                        earlycon_init_is_deferred = true;
                        return 0;
                } else {
                        return early_init_dt_scan_chosen_stdout();
                }
        }

        err = setup_earlycon(buf);
        if (err == -ENOENT || err == -EALREADY)
                return 0;
        return err;
}
early_param("earlycon", param_setup_earlycon);

#ifdef CONFIG_OF_EARLY_FLATTREE

int __init of_setup_earlycon(const struct earlycon_id *match,
                             unsigned long node,
                             const char *options)
{
        int err;
        struct uart_port *port = &early_console_dev.port;
        const __be32 *val;
        bool big_endian;
        u64 addr;

        spin_lock_init(&port->lock);
        port->iotype = UPIO_MEM;
        addr = of_flat_dt_translate_address(node);
        if (addr == OF_BAD_ADDR) {
                pr_warn("[%s] bad address\n", match->name);
                return -ENXIO;
        }
        port->mapbase = addr;
        port->uartclk = BASE_BAUD * 16;
        port->membase = earlycon_map(port->mapbase, SZ_4K);

        val = of_get_flat_dt_prop(node, "reg-offset", NULL);
        if (val)
                port->mapbase += be32_to_cpu(*val);
        val = of_get_flat_dt_prop(node, "reg-shift", NULL);
        if (val)
                port->regshift = be32_to_cpu(*val);
        big_endian = of_get_flat_dt_prop(node, "big-endian", NULL) != NULL ||
                (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) &&
                 of_get_flat_dt_prop(node, "native-endian", NULL) != NULL);
        val = of_get_flat_dt_prop(node, "reg-io-width", NULL);
        if (val) {
                switch (be32_to_cpu(*val)) {
                case 1:
                        port->iotype = UPIO_MEM;
                        break;
                case 2:
                        port->iotype = UPIO_MEM16;
                        break;
                case 4:
                        port->iotype = (big_endian) ? UPIO_MEM32BE : UPIO_MEM32;
                        break;
                default:
                        pr_warn("[%s] unsupported reg-io-width\n", match->name);
                        return -EINVAL;
                }
        }

        if (options) {
                strlcpy(early_console_dev.options, options,
                        sizeof(early_console_dev.options));
        }
        earlycon_init(&early_console_dev, match->name);
        err = match->setup(&early_console_dev, options);
        if (err < 0)
                return err;
        if (!early_console_dev.con->write)
                return -ENODEV;


        register_console(early_console_dev.con);
        return 0;
}

#endif /* CONFIG_OF_EARLY_FLATTREE */