/*
 *  linux/arch/arm/mach-sa1100/cpu-sa1110.c
 *
 *  Copyright (C) 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.
 *
 * Note: there are two erratas that apply to the SA1110 here:
 *  7 - SDRAM auto-power-up failure (rev A0)
 * 13 - Corruption of internal register reads/writes following
 *      SDRAM reads (rev A0, B0, B1)
 *
 * We ignore rev. A0 and B0 devices; I don't think they're worth supporting.
 *
 * The SDRAM type can be passed on the command line as cpu_sa1110.sdram=type
 */
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/moduleparam.h>
#include <linux/types.h>

#include <asm/cputype.h>
#include <asm/mach-types.h>

#include <mach/generic.h>
#include <mach/hardware.h>

#undef DEBUG

struct sdram_params {
        const char name[20];
        u_char  rows;           /* bits                          */
        u_char  cas_latency;    /* cycles                        */
        u_char  tck;            /* clock cycle time (ns)         */
        u_char  trcd;           /* activate to r/w (ns)          */
        u_char  trp;            /* precharge to activate (ns)    */
        u_char  twr;            /* write recovery time (ns)      */
        u_short refresh;        /* refresh time for array (us)   */
};

struct sdram_info {
        u_int   mdcnfg;
        u_int   mdrefr;
        u_int   mdcas[3];
};

static struct sdram_params sdram_tbl[] __initdata = {
        {       /* Toshiba TC59SM716 CL2 */
                .name           = "TC59SM716-CL2",
                .rows           = 12,
                .tck            = 10,
                .trcd           = 20,
                .trp            = 20,
                .twr            = 10,
                .refresh        = 64000,
                .cas_latency    = 2,
        }, {    /* Toshiba TC59SM716 CL3 */
                .name           = "TC59SM716-CL3",
                .rows           = 12,
                .tck            = 8,
                .trcd           = 20,
                .trp            = 20,
                .twr            = 8,
                .refresh        = 64000,
                .cas_latency    = 3,
        }, {    /* Samsung K4S641632D TC75 */
                .name           = "K4S641632D",
                .rows           = 14,
                .tck            = 9,
                .trcd           = 27,
                .trp            = 20,
                .twr            = 9,
                .refresh        = 64000,
                .cas_latency    = 3,
        }, {    /* Samsung K4S281632B-1H */
                .name           = "K4S281632B-1H",
                .rows           = 12,
                .tck            = 10,
                .trp            = 20,
                .twr            = 10,
                .refresh        = 64000,
                .cas_latency    = 3,
        }, {    /* Samsung KM416S4030CT */
                .name           = "KM416S4030CT",
                .rows           = 13,
                .tck            = 8,
                .trcd           = 24,   /* 3 CLKs */
                .trp            = 24,   /* 3 CLKs */
                .twr            = 16,   /* Trdl: 2 CLKs */
                .refresh        = 64000,
                .cas_latency    = 3,
        }, {    /* Winbond W982516AH75L CL3 */
                .name           = "W982516AH75L",
                .rows           = 16,
                .tck            = 8,
                .trcd           = 20,
                .trp            = 20,
                .twr            = 8,
                .refresh        = 64000,
                .cas_latency    = 3,
        }, {    /* Micron MT48LC8M16A2TG-75 */
                .name           = "MT48LC8M16A2TG-75",
                .rows           = 12,
                .tck            = 8,
                .trcd           = 20,
                .trp            = 20,
                .twr            = 8,
                .refresh        = 64000,
                .cas_latency    = 3,
        },
};

static struct sdram_params sdram_params;

/*
 * Given a period in ns and frequency in khz, calculate the number of
 * cycles of frequency in period.  Note that we round up to the next
 * cycle, even if we are only slightly over.
 */
static inline u_int ns_to_cycles(u_int ns, u_int khz)
{
        return (ns * khz + 999999) / 1000000;
}

/*
 * Create the MDCAS register bit pattern.
 */
static inline void set_mdcas(u_int *mdcas, int delayed, u_int rcd)
{
        u_int shift;

        rcd = 2 * rcd - 1;
        shift = delayed + 1 + rcd;

        mdcas[0]  = (1 << rcd) - 1;
        mdcas[0] |= 0x55555555 << shift;
        mdcas[1]  = mdcas[2] = 0x55555555 << (shift & 1);
}

static void
sdram_calculate_timing(struct sdram_info *sd, u_int cpu_khz,
                       struct sdram_params *sdram)
{
        u_int mem_khz, sd_khz, trp, twr;

        mem_khz = cpu_khz / 2;
        sd_khz = mem_khz;

        /*
         * If SDCLK would invalidate the SDRAM timings,
         * run SDCLK at half speed.
         *
         * CPU steppings prior to B2 must either run the memory at
         * half speed or use delayed read latching (errata 13).
         */
        if ((ns_to_cycles(sdram->tck, sd_khz) > 1) ||
            (read_cpuid_revision() < ARM_CPU_REV_SA1110_B2 && sd_khz < 62000))
                sd_khz /= 2;

        sd->mdcnfg = MDCNFG & 0x007f007f;

        twr = ns_to_cycles(sdram->twr, mem_khz);

        /* trp should always be >1 */
        trp = ns_to_cycles(sdram->trp, mem_khz) - 1;
        if (trp < 1)
                trp = 1;

        sd->mdcnfg |= trp << 8;
        sd->mdcnfg |= trp << 24;
        sd->mdcnfg |= sdram->cas_latency << 12;
        sd->mdcnfg |= sdram->cas_latency << 28;
        sd->mdcnfg |= twr << 14;
        sd->mdcnfg |= twr << 30;

        sd->mdrefr = MDREFR & 0xffbffff0;
        sd->mdrefr |= 7;

        if (sd_khz != mem_khz)
                sd->mdrefr |= MDREFR_K1DB2;

        /* initial number of '1's in MDCAS + 1 */
        set_mdcas(sd->mdcas, sd_khz >= 62000,
                ns_to_cycles(sdram->trcd, mem_khz));

#ifdef DEBUG
        printk(KERN_DEBUG "MDCNFG: %08x MDREFR: %08x MDCAS0: %08x MDCAS1: %08x MDCAS2: %08x\n",
                sd->mdcnfg, sd->mdrefr, sd->mdcas[0], sd->mdcas[1],
                sd->mdcas[2]);
#endif
}

/*
 * Set the SDRAM refresh rate.
 */
static inline void sdram_set_refresh(u_int dri)
{
        MDREFR = (MDREFR & 0xffff000f) | (dri << 4);
        (void) MDREFR;
}

/*
 * Update the refresh period.  We do this such that we always refresh
 * the SDRAMs within their permissible period.  The refresh period is
 * always a multiple of the memory clock (fixed at cpu_clock / 2).
 *
 * FIXME: we don't currently take account of burst accesses here,
 * but neither do Intels DM nor Angel.
 */
static void
sdram_update_refresh(u_int cpu_khz, struct sdram_params *sdram)
{
        u_int ns_row = (sdram->refresh * 1000) >> sdram->rows;
        u_int dri = ns_to_cycles(ns_row, cpu_khz / 2) / 32;

#ifdef DEBUG
        mdelay(250);
        printk(KERN_DEBUG "new dri value = %d\n", dri);
#endif

        sdram_set_refresh(dri);
}

/*
 * Ok, set the CPU frequency.
 */
static int sa1110_target(struct cpufreq_policy *policy, unsigned int ppcr)
{
        struct sdram_params *sdram = &sdram_params;
        struct sdram_info sd;
        unsigned long flags;
        unsigned int unused;

        sdram_calculate_timing(&sd, sa11x0_freq_table[ppcr].frequency, sdram);

#if 0
        /*
         * These values are wrong according to the SA1110 documentation
         * and errata, but they seem to work.  Need to get a storage
         * scope on to the SDRAM signals to work out why.
         */
        if (policy->max < 147500) {
                sd.mdrefr |= MDREFR_K1DB2;
                sd.mdcas[0] = 0xaaaaaa7f;
        } else {
                sd.mdrefr &= ~MDREFR_K1DB2;
                sd.mdcas[0] = 0xaaaaaa9f;
        }
        sd.mdcas[1] = 0xaaaaaaaa;
        sd.mdcas[2] = 0xaaaaaaaa;
#endif

        /*
         * The clock could be going away for some time.  Set the SDRAMs
         * to refresh rapidly (every 64 memory clock cycles).  To get
         * through the whole array, we need to wait 262144 mclk cycles.
         * We wait 20ms to be safe.
         */
        sdram_set_refresh(2);
        if (!irqs_disabled())
                msleep(20);
        else
                mdelay(20);

        /*
         * Reprogram the DRAM timings with interrupts disabled, and
         * ensure that we are doing this within a complete cache line.
         * This means that we won't access SDRAM for the duration of
         * the programming.
         */
        local_irq_save(flags);
        asm("mcr p15, 0, %0, c7, c10, 4" : : "r" (0));
        udelay(10);
        __asm__ __volatile__("\n\
                b       2f                                      \n\
                .align  5                                       \n\
1:              str     %3, [%1, #0]            @ MDCNFG        \n\
                str     %4, [%1, #28]           @ MDREFR        \n\
                str     %5, [%1, #4]            @ MDCAS0        \n\
                str     %6, [%1, #8]            @ MDCAS1        \n\
                str     %7, [%1, #12]           @ MDCAS2        \n\
                str     %8, [%2, #0]            @ PPCR          \n\
                ldr     %0, [%1, #0]                            \n\
                b       3f                                      \n\
2:              b       1b                                      \n\
3:              nop                                             \n\
                nop"
                : "=&r" (unused)
                : "r" (&MDCNFG), "r" (&PPCR), "0" (sd.mdcnfg),
                  "r" (sd.mdrefr), "r" (sd.mdcas[0]),
                  "r" (sd.mdcas[1]), "r" (sd.mdcas[2]), "r" (ppcr));
        local_irq_restore(flags);

        /*
         * Now, return the SDRAM refresh back to normal.
         */
        sdram_update_refresh(sa11x0_freq_table[ppcr].frequency, sdram);

        return 0;
}

static int __init sa1110_cpu_init(struct cpufreq_policy *policy)
{
        return cpufreq_generic_init(policy, sa11x0_freq_table, 0);
}

/* sa1110_driver needs __refdata because it must remain after init registers
 * it with cpufreq_register_driver() */
static struct cpufreq_driver sa1110_driver __refdata = {
        .flags          = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK |
                          CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
        .verify         = cpufreq_generic_frequency_table_verify,
        .target_index   = sa1110_target,
        .get            = sa11x0_getspeed,
        .init           = sa1110_cpu_init,
        .name           = "sa1110",
};

static struct sdram_params *sa1110_find_sdram(const char *name)
{
        struct sdram_params *sdram;

        for (sdram = sdram_tbl; sdram < sdram_tbl + ARRAY_SIZE(sdram_tbl);
             sdram++)
                if (strcmp(name, sdram->name) == 0)
                        return sdram;

        return NULL;
}

static char sdram_name[16];

static int __init sa1110_clk_init(void)
{
        struct sdram_params *sdram;
        const char *name = sdram_name;

        if (!cpu_is_sa1110())
                return -ENODEV;

        if (!name[0]) {
                if (machine_is_assabet())
                        name = "TC59SM716-CL3";
                if (machine_is_pt_system3())
                        name = "K4S641632D";
                if (machine_is_h3100())
                        name = "KM416S4030CT";
                if (machine_is_jornada720() || machine_is_h3600())
                        name = "K4S281632B-1H";
                if (machine_is_nanoengine())
                        name = "MT48LC8M16A2TG-75";
        }

        sdram = sa1110_find_sdram(name);
        if (sdram) {
                printk(KERN_DEBUG "SDRAM: tck: %d trcd: %d trp: %d"
                        " twr: %d refresh: %d cas_latency: %d\n",
                        sdram->tck, sdram->trcd, sdram->trp,
                        sdram->twr, sdram->refresh, sdram->cas_latency);

                memcpy(&sdram_params, sdram, sizeof(sdram_params));

                return cpufreq_register_driver(&sa1110_driver);
        }

        return 0;
}

module_param_string(sdram, sdram_name, sizeof(sdram_name), 0);
arch_initcall(sa1110_clk_init);