usbgecko_udbg.c

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/*
 * arch/powerpc/platforms/embedded6xx/usbgecko_udbg.c
 *
 * udbg serial input/output routines for the USB Gecko adapter.
 * Copyright (C) 2008-2009 The GameCube Linux Team
 * Copyright (C) 2008,2009 Albert Herranz
 *
 * 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 <mm/mmu_decl.h>

#include <asm/io.h>
#include <asm/prom.h>
#include <asm/udbg.h>
#include <asm/fixmap.h>

#include "usbgecko_udbg.h"


#define EXI_CLK_32MHZ           5

#define EXI_CSR                 0x00
#define   EXI_CSR_CLKMASK       (0x7<<4)
#define     EXI_CSR_CLK_32MHZ   (EXI_CLK_32MHZ<<4)
#define   EXI_CSR_CSMASK        (0x7<<7)
#define     EXI_CSR_CS_0        (0x1<<7)  /* Chip Select 001 */

#define EXI_CR                  0x0c
#define   EXI_CR_TSTART         (1<<0)
#define   EXI_CR_WRITE      (1<<2)
#define   EXI_CR_READ_WRITE     (2<<2)
#define   EXI_CR_TLEN(len)      (((len)-1)<<4)

#define EXI_DATA                0x10

#define UG_READ_ATTEMPTS    100
#define UG_WRITE_ATTEMPTS   100


static void __iomem *ug_io_base;

/*
 * Performs one input/output transaction between the exi host and the usbgecko.
 */
static u32 ug_io_transaction(u32 in)
{
    u32 __iomem *csr_reg = ug_io_base + EXI_CSR;
    u32 __iomem *data_reg = ug_io_base + EXI_DATA;
    u32 __iomem *cr_reg = ug_io_base + EXI_CR;
    u32 csr, data, cr;

    /* select */
    csr = EXI_CSR_CLK_32MHZ | EXI_CSR_CS_0;
    out_be32(csr_reg, csr);

    /* read/write */
    data = in;
    out_be32(data_reg, data);
    cr = EXI_CR_TLEN(2) | EXI_CR_READ_WRITE | EXI_CR_TSTART;
    out_be32(cr_reg, cr);

    while (in_be32(cr_reg) & EXI_CR_TSTART)
        barrier();

    /* deselect */
    out_be32(csr_reg, 0);

    /* result */
    data = in_be32(data_reg);

    return data;
}

/*
 * Returns true if an usbgecko adapter is found.
 */
static int ug_is_adapter_present(void)
{
    if (!ug_io_base)
        return 0;

    return ug_io_transaction(0x90000000) == 0x04700000;
}

/*
 * Returns true if the TX fifo is ready for transmission.
 */
static int ug_is_txfifo_ready(void)
{
    return ug_io_transaction(0xc0000000) & 0x04000000;
}

/*
 * Tries to transmit a character.
 * If the TX fifo is not ready the result is undefined.
 */
static void ug_raw_putc(char ch)
{
    ug_io_transaction(0xb0000000 | (ch << 20));
}

/*
 * Transmits a character.
 * It silently fails if the TX fifo is not ready after a number of retries.
 */
static void ug_putc(char ch)
{
    int count = UG_WRITE_ATTEMPTS;

    if (!ug_io_base)
        return;

    if (ch == '\n')
        ug_putc('\r');

    while (!ug_is_txfifo_ready() && count--)
        barrier();
    if (count >= 0)
        ug_raw_putc(ch);
}

/*
 * Returns true if the RX fifo is ready for transmission.
 */
static int ug_is_rxfifo_ready(void)
{
    return ug_io_transaction(0xd0000000) & 0x04000000;
}

/*
 * Tries to receive a character.
 * If a character is unavailable the function returns -1.
 */
static int ug_raw_getc(void)
{
    u32 data = ug_io_transaction(0xa0000000);
    if (data & 0x08000000)
        return (data >> 16) & 0xff;
    else
        return -1;
}

/*
 * Receives a character.
 * It fails if the RX fifo is not ready after a number of retries.
 */
static int ug_getc(void)
{
    int count = UG_READ_ATTEMPTS;

    if (!ug_io_base)
        return -1;

    while (!ug_is_rxfifo_ready() && count--)
        barrier();
    return ug_raw_getc();
}

/*
 * udbg functions.
 *
 */

/*
 * Transmits a character.
 */
void ug_udbg_putc(char ch)
{
    ug_putc(ch);
}

/*
 * Receives a character. Waits until a character is available.
 */
static int ug_udbg_getc(void)
{
    int ch;

    while ((ch = ug_getc()) == -1)
        barrier();
    return ch;
}

/*
 * Receives a character. If a character is not available, returns -1.
 */
static int ug_udbg_getc_poll(void)
{
    if (!ug_is_rxfifo_ready())
        return -1;
    return ug_getc();
}

/*
 * Retrieves and prepares the virtual address needed to access the hardware.
 */
static void __iomem *ug_udbg_setup_exi_io_base(struct device_node *np)
{
    void __iomem *exi_io_base = NULL;
    phys_addr_t paddr;
    const unsigned int *reg;

    reg = of_get_property(np, "reg", NULL);
    if (reg) {
        paddr = of_translate_address(np, reg);
        if (paddr)
            exi_io_base = ioremap(paddr, reg[1]);
    }
    return exi_io_base;
}

/*
 * Checks if a USB Gecko adapter is inserted in any memory card slot.
 */
static void __iomem *ug_udbg_probe(void __iomem *exi_io_base)
{
    int i;

    /* look for a usbgecko on memcard slots A and B */
    for (i = 0; i < 2; i++) {
        ug_io_base = exi_io_base + 0x14 * i;
        if (ug_is_adapter_present())
            break;
    }
    if (i == 2)
        ug_io_base = NULL;
    return ug_io_base;

}

/*
 * USB Gecko udbg support initialization.
 */
void __init ug_udbg_init(void)
{
    struct device_node *np;
    void __iomem *exi_io_base;

    if (ug_io_base)
        udbg_printf("%s: early -> final\n", __func__);

    np = of_find_compatible_node(NULL, NULL, "nintendo,flipper-exi");
    if (!np) {
        udbg_printf("%s: EXI node not found\n", __func__);
        goto done;
    }

    exi_io_base = ug_udbg_setup_exi_io_base(np);
    if (!exi_io_base) {
        udbg_printf("%s: failed to setup EXI io base\n", __func__);
        goto done;
    }

    if (!ug_udbg_probe(exi_io_base)) {
        udbg_printf("usbgecko_udbg: not found\n");
        iounmap(exi_io_base);
    } else {
        udbg_putc = ug_udbg_putc;
        udbg_getc = ug_udbg_getc;
        udbg_getc_poll = ug_udbg_getc_poll;
        udbg_printf("usbgecko_udbg: ready\n");
    }

done:
    if (np)
        of_node_put(np);
    return;
}

#ifdef CONFIG_PPC_EARLY_DEBUG_USBGECKO

static phys_addr_t __init ug_early_grab_io_addr(void)
{
#if defined(CONFIG_GAMECUBE)
    return 0x0c000000;
#elif defined(CONFIG_WII)
    return 0x0d000000;
#else
#error Invalid platform for USB Gecko based early debugging.
#endif
}

/*
 * USB Gecko early debug support initialization for udbg.
 */
void __init udbg_init_usbgecko(void)
{
    void __iomem *early_debug_area;
    void __iomem *exi_io_base;

    /*
     * At this point we have a BAT already setup that enables I/O
     * to the EXI hardware.
     *
     * The BAT uses a virtual address range reserved at the fixmap.
     * This must match the virtual address configured in
     * head_32.S:setup_usbgecko_bat().
     */
    early_debug_area = (void __iomem *)__fix_to_virt(FIX_EARLY_DEBUG_BASE);
    exi_io_base = early_debug_area + 0x00006800;

    /* try to detect a USB Gecko */
    if (!ug_udbg_probe(exi_io_base))
        return;

    /* we found a USB Gecko, load udbg hooks */
    udbg_putc = ug_udbg_putc;
    udbg_getc = ug_udbg_getc;
    udbg_getc_poll = ug_udbg_getc_poll;

    /*
     * Prepare again the same BAT for MMU_init.
     * This allows udbg I/O to continue working after the MMU is
     * turned on for real.
     * It is safe to continue using the same virtual address as it is
     * a reserved fixmap area.
     */
    setbat(1, (unsigned long)early_debug_area,
           ug_early_grab_io_addr(), 128*1024, PAGE_KERNEL_NCG);
}

#endif /* CONFIG_PPC_EARLY_DEBUG_USBGECKO */