core.c

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/*
 *  linux/arch/arm/mach-ebsa110/core.c
 *
 *  Copyright (C) 1998-2001 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  Extra MM routines for the EBSA-110 architecture
 */
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/serial_8250.h>
#include <linux/init.h>
#include <linux/io.h>

#include <mach/hardware.h>
#include <asm/irq.h>
#include <asm/setup.h>
#include <asm/mach-types.h>
#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/system_misc.h>

#include <asm/mach/arch.h>
#include <asm/mach/irq.h>
#include <asm/mach/map.h>

#include <asm/mach/time.h>

#include "core.h"

static void ebsa110_mask_irq(struct irq_data *d)
{
    __raw_writeb(1 << d->irq, IRQ_MCLR);
}

static void ebsa110_unmask_irq(struct irq_data *d)
{
    __raw_writeb(1 << d->irq, IRQ_MSET);
}

static struct irq_chip ebsa110_irq_chip = {
    .irq_ack    = ebsa110_mask_irq,
    .irq_mask   = ebsa110_mask_irq,
    .irq_unmask = ebsa110_unmask_irq,
};
 
static void __init ebsa110_init_irq(void)
{
    unsigned long flags;
    unsigned int irq;

    local_irq_save(flags);
    __raw_writeb(0xff, IRQ_MCLR);
    __raw_writeb(0x55, IRQ_MSET);
    __raw_writeb(0x00, IRQ_MSET);
    if (__raw_readb(IRQ_MASK) != 0x55)
        while (1);
    __raw_writeb(0xff, IRQ_MCLR);   /* clear all interrupt enables */
    local_irq_restore(flags);

    for (irq = 0; irq < NR_IRQS; irq++) {
        irq_set_chip_and_handler(irq, &ebsa110_irq_chip,
                     handle_level_irq);
        set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
    }
}

static struct map_desc ebsa110_io_desc[] __initdata = {
    /*
     * sparse external-decode ISAIO space
     */
    {   /* IRQ_STAT/IRQ_MCLR */
        .virtual    = (unsigned long)IRQ_STAT,
        .pfn        = __phys_to_pfn(TRICK4_PHYS),
        .length     = TRICK4_SIZE,
        .type       = MT_DEVICE
    }, {    /* IRQ_MASK/IRQ_MSET */
        .virtual    = (unsigned long)IRQ_MASK,
        .pfn        = __phys_to_pfn(TRICK3_PHYS),
        .length     = TRICK3_SIZE,
        .type       = MT_DEVICE
    }, {    /* SOFT_BASE */
        .virtual    = (unsigned long)SOFT_BASE,
        .pfn        = __phys_to_pfn(TRICK1_PHYS),
        .length     = TRICK1_SIZE,
        .type       = MT_DEVICE
    }, {    /* PIT_BASE */
        .virtual    = (unsigned long)PIT_BASE,
        .pfn        = __phys_to_pfn(TRICK0_PHYS),
        .length     = TRICK0_SIZE,
        .type       = MT_DEVICE
    },

    /*
     * self-decode ISAIO space
     */
    {
        .virtual    = ISAIO_BASE,
        .pfn        = __phys_to_pfn(ISAIO_PHYS),
        .length     = ISAIO_SIZE,
        .type       = MT_DEVICE
    }, {
        .virtual    = ISAMEM_BASE,
        .pfn        = __phys_to_pfn(ISAMEM_PHYS),
        .length     = ISAMEM_SIZE,
        .type       = MT_DEVICE
    }
};

static void __init ebsa110_map_io(void)
{
    iotable_init(ebsa110_io_desc, ARRAY_SIZE(ebsa110_io_desc));
}

static void __iomem *ebsa110_ioremap_caller(unsigned long cookie, size_t size,
                        unsigned int flags, void *caller)
{
    return (void __iomem *)cookie;
}

static void ebsa110_iounmap(volatile void __iomem *io_addr)
{}

static void __init ebsa110_init_early(void)
{
    arch_ioremap_caller = ebsa110_ioremap_caller;
    arch_iounmap = ebsa110_iounmap;
}

#define PIT_CTRL        (PIT_BASE + 0x0d)
#define PIT_T2          (PIT_BASE + 0x09)
#define PIT_T1          (PIT_BASE + 0x05)
#define PIT_T0          (PIT_BASE + 0x01)

/*
 * This is the rate at which your MCLK signal toggles (in Hz)
 * This was measured on a 10 digit frequency counter sampling
 * over 1 second.
 */
#define MCLK    47894000

/*
 * This is the rate at which the PIT timers get clocked
 */
#define CLKBY7  (MCLK / 7)

/*
 * This is the counter value.  We tick at 200Hz on this platform.
 */
#define COUNT   ((CLKBY7 + (HZ / 2)) / HZ)

/*
 * Get the time offset from the system PIT.  Note that if we have missed an
 * interrupt, then the PIT counter will roll over (ie, be negative).
 * This actually works out to be convenient.
 */
static unsigned long ebsa110_gettimeoffset(void)
{
    unsigned long offset, count;

    __raw_writeb(0x40, PIT_CTRL);
    count = __raw_readb(PIT_T1);
    count |= __raw_readb(PIT_T1) << 8;

    /*
     * If count > COUNT, make the number negative.
     */
    if (count > COUNT)
        count |= 0xffff0000;

    offset = COUNT;
    offset -= count;

    /*
     * `offset' is in units of timer counts.  Convert
     * offset to units of microseconds.
     */
    offset = offset * (1000000 / HZ) / COUNT;

    return offset;
}

static irqreturn_t
ebsa110_timer_interrupt(int irq, void *dev_id)
{
    u32 count;

    /* latch and read timer 1 */
    __raw_writeb(0x40, PIT_CTRL);
    count = __raw_readb(PIT_T1);
    count |= __raw_readb(PIT_T1) << 8;

    count += COUNT;

    __raw_writeb(count & 0xff, PIT_T1);
    __raw_writeb(count >> 8, PIT_T1);

    timer_tick();

    return IRQ_HANDLED;
}

static struct irqaction ebsa110_timer_irq = {
    .name       = "EBSA110 Timer Tick",
    .flags      = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
    .handler    = ebsa110_timer_interrupt,
};

/*
 * Set up timer interrupt.
 */
static void __init ebsa110_timer_init(void)
{
    /*
     * Timer 1, mode 2, LSB/MSB
     */
    __raw_writeb(0x70, PIT_CTRL);
    __raw_writeb(COUNT & 0xff, PIT_T1);
    __raw_writeb(COUNT >> 8, PIT_T1);

    setup_irq(IRQ_EBSA110_TIMER0, &ebsa110_timer_irq);
}

static struct sys_timer ebsa110_timer = {
    .init       = ebsa110_timer_init,
    .offset     = ebsa110_gettimeoffset,
};

static struct plat_serial8250_port serial_platform_data[] = {
    {
        .iobase     = 0x3f8,
        .irq        = 1,
        .uartclk    = 1843200,
        .regshift   = 0,
        .iotype     = UPIO_PORT,
        .flags      = UPF_BOOT_AUTOCONF | UPF_SKIP_TEST,
    },
    {
        .iobase     = 0x2f8,
        .irq        = 2,
        .uartclk    = 1843200,
        .regshift   = 0,
        .iotype     = UPIO_PORT,
        .flags      = UPF_BOOT_AUTOCONF | UPF_SKIP_TEST,
    },
    { },
};

static struct platform_device serial_device = {
    .name           = "serial8250",
    .id         = PLAT8250_DEV_PLATFORM,
    .dev            = {
        .platform_data  = serial_platform_data,
    },
};

static struct resource am79c961_resources[] = {
    {
        .start      = 0x220,
        .end        = 0x238,
        .flags      = IORESOURCE_IO,
    }, {
        .start      = IRQ_EBSA110_ETHERNET,
        .end        = IRQ_EBSA110_ETHERNET,
        .flags      = IORESOURCE_IRQ,
    },
};

static struct platform_device am79c961_device = {
    .name           = "am79c961",
    .id         = -1,
    .num_resources      = ARRAY_SIZE(am79c961_resources),
    .resource       = am79c961_resources,
};

static struct platform_device *ebsa110_devices[] = {
    &serial_device,
    &am79c961_device,
};

/*
 * EBSA110 idling methodology:
 *
 * We can not execute the "wait for interrupt" instruction since that
 * will stop our MCLK signal (which provides the clock for the glue
 * logic, and therefore the timer interrupt).
 *
 * Instead, we spin, polling the IRQ_STAT register for the occurrence
 * of any interrupt with core clock down to the memory clock.
 */
static void ebsa110_idle(void)
{
    const char *irq_stat = (char *)0xff000000;

    /* disable clock switching */
    asm volatile ("mcr p15, 0, ip, c15, c2, 2" : : : "cc");

    /* wait for an interrupt to occur */
    while (!*irq_stat);

    /* enable clock switching */
    asm volatile ("mcr p15, 0, ip, c15, c1, 2" : : : "cc");
}

static int __init ebsa110_init(void)
{
    arm_pm_idle = ebsa110_idle;
    return platform_add_devices(ebsa110_devices, ARRAY_SIZE(ebsa110_devices));
}

arch_initcall(ebsa110_init);

static void ebsa110_restart(char mode, const char *cmd)
{
    soft_restart(0x80000000);
}

MACHINE_START(EBSA110, "EBSA110")
    /* Maintainer: Russell King */
    .atag_offset    = 0x400,
    .reserve_lp0    = 1,
    .reserve_lp2    = 1,
    .restart_mode   = 's',
    .map_io     = ebsa110_map_io,
    .init_early = ebsa110_init_early,
    .init_irq   = ebsa110_init_irq,
    .timer      = &ebsa110_timer,
    .restart    = ebsa110_restart,
MACHINE_END