udbg_scc.c

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/*
 * udbg for zilog scc ports as found on Apple PowerMacs
 *
 * Copyright (C) 2001-2005 PPC 64 Team, IBM Corp
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */
#include <linux/types.h>
#include <asm/udbg.h>
#include <asm/processor.h>
#include <asm/io.h>
#include <asm/prom.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 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, x;

    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 (ch = NULL; (ch = of_get_next_child(escc, ch)) != NULL;) {
        if (ch == stdout)
            ch_def = of_node_get(ch);
        if (strcmp(ch->name, "ch-a") == 0)
            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)
        x = 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 */