/*
 * MIPS SPRAM support
 *
 * 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.
 *
 * Copyright (C) 2007, 2008 MIPS Technologies, Inc.
 */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/stddef.h>

#include <asm/cpu.h>
#include <asm/fpu.h>
#include <asm/mipsregs.h>
#include <asm/system.h>
#include <asm/r4kcache.h>
#include <asm/hazards.h>

/*
 * These definitions are correct for the 24K/34K/74K SPRAM sample
 * implementation. The 4KS interpreted the tags differently...
 */
#define SPRAM_TAG0_ENABLE       0x00000080
#define SPRAM_TAG0_PA_MASK      0xfffff000
#define SPRAM_TAG1_SIZE_MASK    0xfffff000

#define SPRAM_TAG_STRIDE        8

#define ERRCTL_SPRAM            (1 << 28)

/* errctl access */
#define read_c0_errctl(x) read_c0_ecc(x)
#define write_c0_errctl(x) write_c0_ecc(x)

/*
 * Different semantics to the set_c0_* function built by __BUILD_SET_C0
 */
static __cpuinit unsigned int bis_c0_errctl(unsigned int set)
{
        unsigned int res;
        res = read_c0_errctl();
        write_c0_errctl(res | set);
        return res;
}

static __cpuinit void ispram_store_tag(unsigned int offset, unsigned int data)
{
        unsigned int errctl;

        /* enable SPRAM tag access */
        errctl = bis_c0_errctl(ERRCTL_SPRAM);
        ehb();

        write_c0_taglo(data);
        ehb();

        cache_op(Index_Store_Tag_I, CKSEG0|offset);
        ehb();

        write_c0_errctl(errctl);
        ehb();
}


static __cpuinit unsigned int ispram_load_tag(unsigned int offset)
{
        unsigned int data;
        unsigned int errctl;

        /* enable SPRAM tag access */
        errctl = bis_c0_errctl(ERRCTL_SPRAM);
        ehb();
        cache_op(Index_Load_Tag_I, CKSEG0 | offset);
        ehb();
        data = read_c0_taglo();
        ehb();
        write_c0_errctl(errctl);
        ehb();

        return data;
}

static __cpuinit void dspram_store_tag(unsigned int offset, unsigned int data)
{
        unsigned int errctl;

        /* enable SPRAM tag access */
        errctl = bis_c0_errctl(ERRCTL_SPRAM);
        ehb();
        write_c0_dtaglo(data);
        ehb();
        cache_op(Index_Store_Tag_D, CKSEG0 | offset);
        ehb();
        write_c0_errctl(errctl);
        ehb();
}


static __cpuinit unsigned int dspram_load_tag(unsigned int offset)
{
        unsigned int data;
        unsigned int errctl;

        errctl = bis_c0_errctl(ERRCTL_SPRAM);
        ehb();
        cache_op(Index_Load_Tag_D, CKSEG0 | offset);
        ehb();
        data = read_c0_dtaglo();
        ehb();
        write_c0_errctl(errctl);
        ehb();

        return data;
}

static __cpuinit void probe_spram(char *type,
            unsigned int base,
            unsigned int (*read)(unsigned int),
            void (*write)(unsigned int, unsigned int))
{
        unsigned int firstsize = 0, lastsize = 0;
        unsigned int firstpa = 0, lastpa = 0, pa = 0;
        unsigned int offset = 0;
        unsigned int size, tag0, tag1;
        unsigned int enabled;
        int i;

        /*
         * The limit is arbitrary but avoids the loop running away if
         * the SPRAM tags are implemented differently
         */

        for (i = 0; i < 8; i++) {
                tag0 = read(offset);
                tag1 = read(offset+SPRAM_TAG_STRIDE);
                pr_debug("DBG %s%d: tag0=%08x tag1=%08x\n",
                         type, i, tag0, tag1);

                size = tag1 & SPRAM_TAG1_SIZE_MASK;

                if (size == 0)
                        break;

                if (i != 0) {
                        /* tags may repeat... */
                        if ((pa == firstpa && size == firstsize) ||
                            (pa == lastpa && size == lastsize))
                                break;
                }

                /* Align base with size */
                base = (base + size - 1) & ~(size-1);

                /* reprogram the base address base address and enable */
                tag0 = (base & SPRAM_TAG0_PA_MASK) | SPRAM_TAG0_ENABLE;
                write(offset, tag0);

                base += size;

                /* reread the tag */
                tag0 = read(offset);
                pa = tag0 & SPRAM_TAG0_PA_MASK;
                enabled = tag0 & SPRAM_TAG0_ENABLE;

                if (i == 0) {
                        firstpa = pa;
                        firstsize = size;
                }

                lastpa = pa;
                lastsize = size;

                if (strcmp(type, "DSPRAM") == 0) {
                        unsigned int *vp = (unsigned int *)(CKSEG1 | pa);
                        unsigned int v;
#define TDAT    0x5a5aa5a5
                        vp[0] = TDAT;
                        vp[1] = ~TDAT;

                        mb();

                        v = vp[0];
                        if (v != TDAT)
                                printk(KERN_ERR "vp=%p wrote=%08x got=%08x\n",
                                       vp, TDAT, v);
                        v = vp[1];
                        if (v != ~TDAT)
                                printk(KERN_ERR "vp=%p wrote=%08x got=%08x\n",
                                       vp+1, ~TDAT, v);
                }

                pr_info("%s%d: PA=%08x,Size=%08x%s\n",
                        type, i, pa, size, enabled ? ",enabled" : "");
                offset += 2 * SPRAM_TAG_STRIDE;
        }
}

__cpuinit void spram_config(void)
{
        struct cpuinfo_mips *c = &current_cpu_data;
        unsigned int config0;

        switch (c->cputype) {
        case CPU_24K:
        case CPU_34K:
        case CPU_74K:
                config0 = read_c0_config();
                /* FIXME: addresses are Malta specific */
                if (config0 & (1<<24)) {
                        probe_spram("ISPRAM", 0x1c000000,
                                    &ispram_load_tag, &ispram_store_tag);
                }
                if (config0 & (1<<23))
                        probe_spram("DSPRAM", 0x1c100000,
                                    &dspram_load_tag, &dspram_store_tag);
        }
}