py-console.c

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/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2001, 2002, 2004 Ralf Baechle
 */
#include <linux/init.h>
#include <linux/console.h>
#include <linux/kdev_t.h>
#include <linux/major.h>
#include <linux/termios.h>
#include <linux/sched.h>
#include <linux/tty.h>

#include <linux/serial.h>
#include <linux/serial_core.h>
#include <asm/serial.h>
#include <asm/io.h>

/* SUPERIO uart register map */
struct yo_uartregs {
    union {
        volatile u8 rbr;    /* read only, DLAB == 0 */
        volatile u8 thr;    /* write only, DLAB == 0 */
        volatile u8 dll;    /* DLAB == 1 */
    } u1;
    union {
        volatile u8 ier;    /* DLAB == 0 */
        volatile u8 dlm;    /* DLAB == 1 */
    } u2;
    union {
        volatile u8 iir;    /* read only */
        volatile u8 fcr;    /* write only */
    } u3;
    volatile u8 iu_lcr;
    volatile u8 iu_mcr;
    volatile u8 iu_lsr;
    volatile u8 iu_msr;
    volatile u8 iu_scr;
} yo_uregs_t;

#define iu_rbr u1.rbr
#define iu_thr u1.thr
#define iu_dll u1.dll
#define iu_ier u2.ier
#define iu_dlm u2.dlm
#define iu_iir u3.iir
#define iu_fcr u3.fcr

#define ssnop()     __asm__ __volatile__("sll   $0, $0, 1\n");
#define ssnop_4()   do { ssnop(); ssnop(); ssnop(); ssnop(); } while (0)

#define IO_BASE_64  0x9000000000000000ULL

static unsigned char readb_outer_space(unsigned long long phys)
{
    unsigned long long vaddr = IO_BASE_64 | phys;
    unsigned char res;
    unsigned int sr;

    sr = read_c0_status();
    write_c0_status((sr | ST0_KX) & ~ ST0_IE);
    ssnop_4();

    __asm__ __volatile__ (
    "   .set    mips3       \n"
    "   ld  %0, %1      \n"
    "   lbu %0, (%0)    \n"
    "   .set    mips0       \n"
    : "=r" (res)
    : "m" (vaddr));

    write_c0_status(sr);
    ssnop_4();

    return res;
}

static void writeb_outer_space(unsigned long long phys, unsigned char c)
{
    unsigned long long vaddr = IO_BASE_64 | phys;
    unsigned long tmp;
    unsigned int sr;

    sr = read_c0_status();
    write_c0_status((sr | ST0_KX) & ~ ST0_IE);
    ssnop_4();

    __asm__ __volatile__ (
    "   .set    mips3       \n"
    "   ld  %0, %1      \n"
    "   sb  %2, (%0)    \n"
    "   .set    mips0       \n"
    : "=&r" (tmp)
    : "m" (vaddr), "r" (c));

    write_c0_status(sr);
    ssnop_4();
}

void prom_putchar(char c)
{
    unsigned long lsr = 0xfd000008ULL + offsetof(struct yo_uartregs, iu_lsr);
    unsigned long thr = 0xfd000008ULL + offsetof(struct yo_uartregs, iu_thr);

    while ((readb_outer_space(lsr) & 0x20) == 0);
    writeb_outer_space(thr, c);
}