/* $Id: chmc.c,v 1.3 2001/04/03 12:49:47 davem Exp $
 * memctrlr.c: Driver for UltraSPARC-III memory controller.
 *
 * Copyright (C) 2001 David S. Miller (davem@redhat.com)
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/init.h>
#include <asm/spitfire.h>
#include <asm/chmctrl.h>
#include <asm/oplib.h>
#include <asm/io.h>

#define CHMCTRL_NDGRPS  2
#define CHMCTRL_NDIMMS  4

#define DIMMS_PER_MC    (CHMCTRL_NDGRPS * CHMCTRL_NDIMMS)

/* OBP memory-layout property format. */
struct obp_map {
        unsigned char   dimm_map[144];
        unsigned char   pin_map[576];
};

#define DIMM_LABEL_SZ   8

struct obp_mem_layout {
        /* One max 8-byte string label per DIMM.  Usually
         * this matches the label on the motherboard where
         * that DIMM resides.
         */
        char            dimm_labels[DIMMS_PER_MC][DIMM_LABEL_SZ];

        /* If symmetric use map[0], else it is
         * asymmetric and map[1] should be used.
         */
        char            symmetric;

        struct obp_map  map[2];
};

#define CHMCTRL_NBANKS  4

struct bank_info {
        struct mctrl_info       *mp;
        int                     bank_id;

        u64                     raw_reg;
        int                     valid;
        int                     uk;
        int                     um;
        int                     lk;
        int                     lm;
        int                     interleave;
        unsigned long           base;
        unsigned long           size;
};

struct mctrl_info {
        struct list_head        list;
        int                     portid;
        int                     index;

        struct obp_mem_layout   layout_prop;
        int                     layout_size;

        void                    *regs;

        u64                     timing_control1;
        u64                     timing_control2;
        u64                     timing_control3;
        u64                     timing_control4;
        u64                     memaddr_control;

        struct bank_info        logical_banks[CHMCTRL_NBANKS];
};

static LIST_HEAD(mctrl_list);

/* Does BANK decode PHYS_ADDR? */
static int bank_match(struct bank_info *bp, unsigned long phys_addr)
{
        unsigned long upper_bits = (phys_addr & PA_UPPER_BITS) >> PA_UPPER_BITS_SHIFT;
        unsigned long lower_bits = (phys_addr & PA_LOWER_BITS) >> PA_LOWER_BITS_SHIFT;

        /* Bank must be enabled to match. */
        if (bp->valid == 0)
                return 0;

        /* Would BANK match upper bits? */
        upper_bits ^= bp->um;           /* What bits are different? */
        upper_bits  = ~upper_bits;      /* Invert. */
        upper_bits |= bp->uk;           /* What bits don't matter for matching? */
        upper_bits  = ~upper_bits;      /* Invert. */

        if (upper_bits)
                return 0;

        /* Would BANK match lower bits? */
        lower_bits ^= bp->lm;           /* What bits are different? */
        lower_bits  = ~lower_bits;      /* Invert. */
        lower_bits |= bp->lk;           /* What bits don't matter for matching? */
        lower_bits  = ~lower_bits;      /* Invert. */

        if (lower_bits)
                return 0;

        /* I always knew you'd be the one. */
        return 1;
}

/* Given PHYS_ADDR, search memory controller banks for a match. */
static struct bank_info *find_bank(unsigned long phys_addr)
{
        struct list_head *mctrl_head = &mctrl_list;
        struct list_head *mctrl_entry = mctrl_head->next;

        for (;;) {
                struct mctrl_info *mp =
                        list_entry(mctrl_entry, struct mctrl_info, list);
                int bank_no;

                if (mctrl_entry == mctrl_head)
                        break;
                mctrl_entry = mctrl_entry->next;

                for (bank_no = 0; bank_no < CHMCTRL_NBANKS; bank_no++) {
                        struct bank_info *bp;

                        bp = &mp->logical_banks[bank_no];
                        if (bank_match(bp, phys_addr))
                                return bp;
                }
        }

        return NULL;
}

/* This is the main purpose of this driver. */
#define SYNDROME_MIN    -1
#define SYNDROME_MAX    144
int chmc_getunumber(int syndrome_code,
                    unsigned long phys_addr,
                    char *buf, int buflen)
{
        struct bank_info *bp;
        struct obp_mem_layout *prop;
        int bank_in_controller, first_dimm;

        bp = find_bank(phys_addr);
        if (bp == NULL ||
            syndrome_code < SYNDROME_MIN ||
            syndrome_code > SYNDROME_MAX) {
                buf[0] = '?';
                buf[1] = '?';
                buf[2] = '?';
                buf[3] = '\0';
                return 0;
        }

        prop = &bp->mp->layout_prop;
        bank_in_controller = bp->bank_id & (CHMCTRL_NBANKS - 1);
        first_dimm  = (bank_in_controller & (CHMCTRL_NDGRPS - 1));
        first_dimm *= CHMCTRL_NDIMMS;

        if (syndrome_code != SYNDROME_MIN) {
                struct obp_map *map;
                int qword, where_in_line, where, map_index, map_offset;
                unsigned int map_val;

                /* Yaay, single bit error so we can figure out
                 * the exact dimm.
                 */
                if (prop->symmetric)
                        map = &prop->map[0];
                else
                        map = &prop->map[1];

                /* Covert syndrome code into the way the bits are
                 * positioned on the bus.
                 */
                if (syndrome_code < 144 - 16)
                        syndrome_code += 16;
                else if (syndrome_code < 144)
                        syndrome_code -= (144 - 7);
                else if (syndrome_code < (144 + 3))
                        syndrome_code -= (144 + 3 - 4);
                else
                        syndrome_code -= 144 + 3;

                /* All this magic has to do with how a cache line
                 * comes over the wire on Safari.  A 64-bit line
                 * comes over in 4 quadword cycles, each of which
                 * transmit ECC/MTAG info as well as the actual
                 * data.  144 bits per quadword, 576 total.
                 */
#define LINE_SIZE       64
#define LINE_ADDR_MSK   (LINE_SIZE - 1)
#define QW_PER_LINE     4
#define QW_BYTES        (LINE_SIZE / QW_PER_LINE)
#define QW_BITS         144
#define LAST_BIT        (576 - 1)

                qword = (phys_addr & LINE_ADDR_MSK) / QW_BYTES;
                where_in_line = ((3 - qword) * QW_BITS) + syndrome_code;
                where = (LAST_BIT - where_in_line);
                map_index = where >> 2;
                map_offset = where & 0x3;
                map_val = map->dimm_map[map_index];
                map_val = ((map_val >> ((3 - map_offset) << 1)) & (2 - 1));

                sprintf(buf, "%s, pin %3d",
                        prop->dimm_labels[first_dimm + map_val],
                        map->pin_map[where_in_line]);
        } else {
                int dimm;

                /* Multi-bit error, we just dump out all the
                 * dimm labels assosciated with this bank.
                 */
                for (dimm = 0; dimm < CHMCTRL_NDIMMS; dimm++) {
                        sprintf(buf, "%s ",
                                prop->dimm_labels[first_dimm + dimm]);
                        buf += strlen(buf);
                }
        }
        return 0;
}

/* Accessing the registers is slightly complicated.  If you want
 * to get at the memory controller which is on the same processor
 * the code is executing, you must use special ASI load/store else
 * you go through the global mapping.
 */
static u64 read_mcreg(struct mctrl_info *mp, unsigned long offset)
{
        unsigned long ret;

        if (mp->portid == smp_processor_id()) {
                __asm__ __volatile__("ldxa      [%1] %2, %0"
                                     : "=r" (ret)
                                     : "r" (offset), "i" (ASI_MCU_CTRL_REG));
        } else {
                __asm__ __volatile__("ldxa      [%1] %2, %0"
                                     : "=r" (ret)
                                     : "r" (mp->regs + offset),
                                       "i" (ASI_PHYS_BYPASS_EC_E));
        }
        return ret;
}

#if 0 /* currently unused */
static void write_mcreg(struct mctrl_info *mp, unsigned long offset, u64 val)
{
        if (mp->portid == smp_processor_id()) {
                __asm__ __volatile__("stxa      %0, [%1] %2"
                                     : : "r" (val),
                                         "r" (offset), "i" (ASI_MCU_CTRL_REG));
        } else {
                __asm__ __volatile__("ldxa      %0, [%1] %2"
                                     : : "r" (val),
                                         "r" (mp->regs + offset),
                                         "i" (ASI_PHYS_BYPASS_EC_E));
        }
}
#endif

static void interpret_one_decode_reg(struct mctrl_info *mp, int which_bank, u64 val)
{
        struct bank_info *p = &mp->logical_banks[which_bank];

        p->mp = mp;
        p->bank_id = (CHMCTRL_NBANKS * mp->portid) + which_bank;
        p->raw_reg = val;
        p->valid = (val & MEM_DECODE_VALID) >> MEM_DECODE_VALID_SHIFT;
        p->uk = (val & MEM_DECODE_UK) >> MEM_DECODE_UK_SHIFT;
        p->um = (val & MEM_DECODE_UM) >> MEM_DECODE_UM_SHIFT;
        p->lk = (val & MEM_DECODE_LK) >> MEM_DECODE_LK_SHIFT;
        p->lm = (val & MEM_DECODE_LM) >> MEM_DECODE_LM_SHIFT;

        p->base  =  (p->um);
        p->base &= ~(p->uk);
        p->base <<= PA_UPPER_BITS_SHIFT;

        switch(p->lk) {
        case 0xf:
        default:
                p->interleave = 1;
                break;

        case 0xe:
                p->interleave = 2;
                break;

        case 0xc:
                p->interleave = 4;
                break;

        case 0x8:
                p->interleave = 8;
                break;

        case 0x0:
                p->interleave = 16;
                break;
        };

        /* UK[10] is reserved, and UK[11] is not set for the SDRAM
         * bank size definition.
         */
        p->size = (((unsigned long)p->uk &
                    ((1UL << 10UL) - 1UL)) + 1UL) << PA_UPPER_BITS_SHIFT;
        p->size /= p->interleave;
}

static void fetch_decode_regs(struct mctrl_info *mp)
{
        if (mp->layout_size == 0)
                return;

        interpret_one_decode_reg(mp, 0,
                                 read_mcreg(mp, CHMCTRL_DECODE1));
        interpret_one_decode_reg(mp, 1,
                                 read_mcreg(mp, CHMCTRL_DECODE2));
        interpret_one_decode_reg(mp, 2,
                                 read_mcreg(mp, CHMCTRL_DECODE3));
        interpret_one_decode_reg(mp, 3,
                                 read_mcreg(mp, CHMCTRL_DECODE4));
}

static int init_one_mctrl(int node, int index)
{
        struct mctrl_info *mp = kmalloc(sizeof(*mp), GFP_KERNEL);
        int portid = prom_getintdefault(node, "portid", -1);
        struct linux_prom64_registers p_reg_prop;
        int t;

        if (!mp)
                return -1;
        memset(mp, 0, sizeof(*mp));
        if (portid == -1)
                goto fail;

        mp->portid = portid;
        mp->layout_size = prom_getproplen(node, "memory-layout");
        if (mp->layout_size < 0)
                mp->layout_size = 0;
        if (mp->layout_size > sizeof(mp->layout_prop))
                goto fail;

        if (mp->layout_size > 0)
                prom_getproperty(node, "memory-layout",
                                 (char *) &mp->layout_prop,
                                 mp->layout_size);

        t = prom_getproperty(node, "reg",
                             (char *) &p_reg_prop,
                             sizeof(p_reg_prop));
        if (t < 0 || p_reg_prop.reg_size != 0x48)
                goto fail;

        mp->regs = ioremap(p_reg_prop.phys_addr, p_reg_prop.reg_size);
        if (mp->regs == NULL)
                goto fail;

        if (mp->layout_size != 0UL) {
                mp->timing_control1 = read_mcreg(mp, CHMCTRL_TCTRL1);
                mp->timing_control2 = read_mcreg(mp, CHMCTRL_TCTRL2);
                mp->timing_control3 = read_mcreg(mp, CHMCTRL_TCTRL3);
                mp->timing_control4 = read_mcreg(mp, CHMCTRL_TCTRL4);
                mp->memaddr_control = read_mcreg(mp, CHMCTRL_MACTRL);
        }

        fetch_decode_regs(mp);

        mp->index = index;

        list_add(&mp->list, &mctrl_list);

        /* Report the device. */
        printk(KERN_INFO "chmc%d: US3 memory controller at %p [%s]\n",
               mp->index,
               mp->regs, (mp->layout_size ? "ACTIVE" : "INACTIVE"));

        return 0;

fail:
        if (mp) {
                if (mp->regs != NULL)
                        iounmap(mp->regs);
                kfree(mp);
        }
        return -1;
}

static int __init probe_for_string(char *name, int index)
{
        int node = prom_getchild(prom_root_node);

        while ((node = prom_searchsiblings(node, name)) != 0) {
                int ret = init_one_mctrl(node, index);

                if (!ret)
                        index++;

                node = prom_getsibling(node);
                if (!node)
                        break;
        }

        return index;
}

static int __init chmc_init(void)
{
        int index;

        /* This driver is only for cheetah platforms. */
        if (tlb_type != cheetah && tlb_type != cheetah_plus)
                return -ENODEV;

        index = probe_for_string("memory-controller", 0);
        index = probe_for_string("mc-us3", index);

        return 0;
}

static void __exit chmc_cleanup(void)
{
        struct list_head *head = &mctrl_list;
        struct list_head *tmp = head->next;

        for (;;) {
                struct mctrl_info *p =
                        list_entry(tmp, struct mctrl_info, list);
                if (tmp == head)
                        break;
                tmp = tmp->next;

                list_del(&p->list);
                iounmap(p->regs);
                kfree(p);
        }
}

module_init(chmc_init);
module_exit(chmc_cleanup);