// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * udbg for zilog scc ports as found on Apple PowerMacs
 *
 * Copyright (C) 2001-2005 PPC 64 Team, IBM Corp
 */
#include <linux/types.h>
#include <linux/of.h>
#include <asm/udbg.h>
#include <asm/processor.h>
#include <asm/io.h>
#include <asm/pmac_feature.h>

extern u8 real_readb(volatile u8 __iomem  *addr);
extern void real_writeb(u8 data, volatile u8 __iomem *addr);

#define SCC_TXRDY       4
#define SCC_RXRDY       1

static volatile u8 __iomem *sccc;
static volatile u8 __iomem *sccd;

static void udbg_scc_putc(char c)
{
        if (sccc) {
                while ((in_8(sccc) & SCC_TXRDY) == 0)
                        ;
                out_8(sccd,  c);
                if (c == '\n')
                        udbg_scc_putc('\r');
        }
}

static int udbg_scc_getc_poll(void)
{
        if (sccc) {
                if ((in_8(sccc) & SCC_RXRDY) != 0)
                        return in_8(sccd);
                else
                        return -1;
        }
        return -1;
}

static int udbg_scc_getc(void)
{
        if (sccc) {
                while ((in_8(sccc) & SCC_RXRDY) == 0)
                        ;
                return in_8(sccd);
        }
        return -1;
}

static unsigned char scc_inittab[] = {
    13, 0,              /* set baud rate divisor */
    12, 0,
    14, 1,              /* baud rate gen enable, src=rtxc */
    11, 0x50,           /* clocks = br gen */
    5,  0xea,           /* tx 8 bits, assert DTR & RTS */
    4,  0x46,           /* x16 clock, 1 stop */
    3,  0xc1,           /* rx enable, 8 bits */
};

void __init udbg_scc_init(int force_scc)
{
        const u32 *reg;
        unsigned long addr;
        struct device_node *stdout = NULL, *escc = NULL, *macio = NULL;
        struct device_node *ch, *ch_def = NULL, *ch_a = NULL;
        const char *path;
        int i;

        escc = of_find_node_by_name(NULL, "escc");
        if (escc == NULL)
                goto bail;
        macio = of_get_parent(escc);
        if (macio == NULL)
                goto bail;
        path = of_get_property(of_chosen, "linux,stdout-path", NULL);
        if (path != NULL)
                stdout = of_find_node_by_path(path);
        for_each_child_of_node(escc, ch) {
                if (ch == stdout) {
                        of_node_put(ch_def);
                        ch_def = of_node_get(ch);
                }
                if (of_node_name_eq(ch, "ch-a")) {
                        of_node_put(ch_a);
                        ch_a = of_node_get(ch);
                }
        }
        if (ch_def == NULL && !force_scc)
                goto bail;

        ch = ch_def ? ch_def : ch_a;

        /* Get address within mac-io ASIC */
        reg = of_get_property(escc, "reg", NULL);
        if (reg == NULL)
                goto bail;
        addr = reg[0];

        /* Get address of mac-io PCI itself */
        reg = of_get_property(macio, "assigned-addresses", NULL);
        if (reg == NULL)
                goto bail;
        addr += reg[2];

        /* Lock the serial port */
        pmac_call_feature(PMAC_FTR_SCC_ENABLE, ch,
                          PMAC_SCC_ASYNC | PMAC_SCC_FLAG_XMON, 1);

        if (ch == ch_a)
                addr += 0x20;
        sccc = ioremap(addr & PAGE_MASK, PAGE_SIZE) ;
        sccc += addr & ~PAGE_MASK;
        sccd = sccc + 0x10;

        mb();

        for (i = 20000; i != 0; --i)
                in_8(sccc);
        out_8(sccc, 0x09);              /* reset A or B side */
        out_8(sccc, 0xc0);

        /* If SCC was the OF output port, read the BRG value, else
         * Setup for 38400 or 57600 8N1 depending on the machine
         */
        if (ch_def != NULL) {
                out_8(sccc, 13);
                scc_inittab[1] = in_8(sccc);
                out_8(sccc, 12);
                scc_inittab[3] = in_8(sccc);
        } else if (of_machine_is_compatible("RackMac1,1")
                   || of_machine_is_compatible("RackMac1,2")
                   || of_machine_is_compatible("MacRISC4")) {
                /* Xserves and G5s default to 57600 */
                scc_inittab[1] = 0;
                scc_inittab[3] = 0;
        } else {
                /* Others default to 38400 */
                scc_inittab[1] = 0;
                scc_inittab[3] = 1;
        }

        for (i = 0; i < sizeof(scc_inittab); ++i)
                out_8(sccc, scc_inittab[i]);


        udbg_putc = udbg_scc_putc;
        udbg_getc = udbg_scc_getc;
        udbg_getc_poll = udbg_scc_getc_poll;

        udbg_puts("Hello World !\n");

 bail:
        of_node_put(macio);
        of_node_put(escc);
        of_node_put(stdout);
        of_node_put(ch_def);
        of_node_put(ch_a);
}

#ifdef CONFIG_PPC64
static void udbg_real_scc_putc(char c)
{
        while ((real_readb(sccc) & SCC_TXRDY) == 0)
                ;
        real_writeb(c, sccd);
        if (c == '\n')
                udbg_real_scc_putc('\r');
}

void __init udbg_init_pmac_realmode(void)
{
        sccc = (volatile u8 __iomem *)0x80013020ul;
        sccd = (volatile u8 __iomem *)0x80013030ul;

        udbg_putc = udbg_real_scc_putc;
        udbg_getc = NULL;
        udbg_getc_poll = NULL;
}
#endif /* CONFIG_PPC64 */