// SPDX-License-Identifier: GPL-2.0-only
/*
 * Joshua Henderson <joshua.henderson@microchip.com>
 * Copyright (C) 2015 Microchip Technology Inc.  All rights reserved.
 */
#include <linux/io.h>
#include <linux/platform_data/pic32.h>
#include <asm/fw/fw.h>
#include <asm/setup.h>

#include "pic32mzda.h"
#include "early_pin.h"

/* Default early console parameters */
#define EARLY_CONSOLE_PORT      1
#define EARLY_CONSOLE_BAUDRATE  115200

#define UART_ENABLE             BIT(15)
#define UART_ENABLE_RX          BIT(12)
#define UART_ENABLE_TX          BIT(10)
#define UART_TX_FULL            BIT(9)

/* UART1(x == 0) - UART6(x == 5) */
#define UART_BASE(x)    ((x) * 0x0200)
#define U_MODE(x)       UART_BASE(x)
#define U_STA(x)        (UART_BASE(x) + 0x10)
#define U_TXR(x)        (UART_BASE(x) + 0x20)
#define U_BRG(x)        (UART_BASE(x) + 0x40)

static void __iomem *uart_base;
static int console_port = -1;

static int __init configure_uart_pins(int port)
{
        switch (port) {
        case 1:
                pic32_pps_input(IN_FUNC_U2RX, IN_RPB0);
                pic32_pps_output(OUT_FUNC_U2TX, OUT_RPG9);
                break;
        case 5:
                pic32_pps_input(IN_FUNC_U6RX, IN_RPD0);
                pic32_pps_output(OUT_FUNC_U6TX, OUT_RPB8);
                break;
        default:
                return -1;
        }

        return 0;
}

static void __init configure_uart(int port, int baud)
{
        u32 pbclk;

        pbclk = pic32_get_pbclk(2);

        __raw_writel(0, uart_base + U_MODE(port));
        __raw_writel(((pbclk / baud) / 16) - 1, uart_base + U_BRG(port));
        __raw_writel(UART_ENABLE, uart_base + U_MODE(port));
        __raw_writel(UART_ENABLE_TX | UART_ENABLE_RX,
                     uart_base + PIC32_SET(U_STA(port)));
}

static void __init setup_early_console(int port, int baud)
{
        if (configure_uart_pins(port))
                return;

        console_port = port;
        configure_uart(console_port, baud);
}

static char * __init pic32_getcmdline(void)
{
        /*
         * arch_mem_init() has not been called yet, so we don't have a real
         * command line setup if using CONFIG_CMDLINE_BOOL.
         */
#ifdef CONFIG_CMDLINE_OVERRIDE
        return CONFIG_CMDLINE;
#else
        return fw_getcmdline();
#endif
}

static int __init get_port_from_cmdline(char *arch_cmdline)
{
        char *s;
        int port = -1;

        if (!arch_cmdline || *arch_cmdline == '\0')
                goto _out;

        s = strstr(arch_cmdline, "earlyprintk=");
        if (s) {
                s = strstr(s, "ttyS");
                if (s)
                        s += 4;
                else
                        goto _out;

                port = (*s) - '0';
        }

_out:
        return port;
}

static int __init get_baud_from_cmdline(char *arch_cmdline)
{
        char *s;
        int baud = -1;

        if (!arch_cmdline || *arch_cmdline == '\0')
                goto _out;

        s = strstr(arch_cmdline, "earlyprintk=");
        if (s) {
                s = strstr(s, "ttyS");
                if (s)
                        s += 6;
                else
                        goto _out;

                baud = 0;
                while (*s >= '0' && *s <= '9')
                        baud = baud * 10 + *s++ - '0';
        }

_out:
        return baud;
}

void __init fw_init_early_console(void)
{
        char *arch_cmdline = pic32_getcmdline();
        int baud, port;

        uart_base = ioremap(PIC32_BASE_UART, 0xc00);

        baud = get_baud_from_cmdline(arch_cmdline);
        port = get_port_from_cmdline(arch_cmdline);

        if (port == -1)
                port = EARLY_CONSOLE_PORT;

        if (baud == -1)
                baud = EARLY_CONSOLE_BAUDRATE;

        setup_early_console(port, baud);
}

void prom_putchar(char c)
{
        if (console_port >= 0) {
                while (__raw_readl(
                                uart_base + U_STA(console_port)) & UART_TX_FULL)
                        ;

                __raw_writel(c, uart_base + U_TXR(console_port));
        }
}