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

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

#include <asm/mach/time.h>

#define IRQ_MASK                0xfe000000      /* read */
#define IRQ_MSET                0xfe000000      /* write */
#define IRQ_STAT                0xff000000      /* read */
#define IRQ_MCLR                0xff000000      /* write */

static void ebsa110_mask_irq(unsigned int irq)
{
        __raw_writeb(1 << irq, IRQ_MCLR);
}

static void ebsa110_unmask_irq(unsigned int irq)
{
        __raw_writeb(1 << irq, IRQ_MSET);
}

static struct irqchip ebsa110_irq_chip = {
        .ack    = ebsa110_mask_irq,
        .mask   = ebsa110_mask_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++) {
                set_irq_chip(irq, &ebsa110_irq_chip);
                set_irq_handler(irq, do_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,    TRICK4_PHYS, PGDIR_SIZE,  MT_DEVICE }, /* IRQ_STAT/IRQ_MCLR */
        { IRQ_MASK,    TRICK3_PHYS, PGDIR_SIZE,  MT_DEVICE }, /* IRQ_MASK/IRQ_MSET */
        { SOFT_BASE,   TRICK1_PHYS, PGDIR_SIZE,  MT_DEVICE }, /* SOFT_BASE */
        { PIT_BASE,    TRICK0_PHYS, PGDIR_SIZE,  MT_DEVICE }, /* PIT_BASE */

        /*
         * self-decode ISAIO space
         */
        { ISAIO_BASE,  ISAIO_PHYS,  ISAIO_SIZE,  MT_DEVICE },
        { ISAMEM_BASE, ISAMEM_PHYS, ISAMEM_SIZE, MT_DEVICE }
};

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


#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, struct pt_regs *regs)
{
        u32 count;

        write_seqlock(&xtime_lock);

        /* 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(regs);

        write_sequnlock(&xtime_lock);

        return IRQ_HANDLED;
}

static struct irqaction ebsa110_timer_irq = {
        .name           = "EBSA110 Timer Tick",
        .flags          = SA_INTERRUPT,
        .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                     = 0,
        .dev                    = {
                .platform_data  = serial_platform_data,
        },
};

static int __init ebsa110_init(void)
{
        return platform_device_register(&serial_device);
}

arch_initcall(ebsa110_init);

MACHINE_START(EBSA110, "EBSA110")
        MAINTAINER("Russell King")
        BOOT_MEM(0x00000000, 0xe0000000, 0xe0000000)
        BOOT_PARAMS(0x00000400)
        DISABLE_PARPORT(0)
        DISABLE_PARPORT(2)
        SOFT_REBOOT
        MAPIO(ebsa110_map_io)
        INITIRQ(ebsa110_init_irq)
        .timer          = &ebsa110_timer,
MACHINE_END