/*
 * Copyright (c) 2006-2009 Simtec Electronics
 *      http://armlinux.simtec.co.uk/
 *      Ben Dooks <ben@simtec.co.uk>
 *
 * S3C24XX CPU Frequency scaling - IO timing for S3C2410/S3C2440/S3C2442
 *
 * 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.
*/

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/cpufreq.h>
#include <linux/seq_file.h>
#include <linux/io.h>
#include <linux/slab.h>

#include <mach/map.h>
#include <mach/regs-clock.h>

#include <plat/cpu-freq-core.h>

#include "regs-mem.h"

#define print_ns(x) ((x) / 10), ((x) % 10)

/**
 * s3c2410_print_timing - print bank timing data for debug purposes
 * @pfx: The prefix to put on the output
 * @timings: The timing inforamtion to print.
*/
static void s3c2410_print_timing(const char *pfx,
                                 struct s3c_iotimings *timings)
{
        struct s3c2410_iobank_timing *bt;
        int bank;

        for (bank = 0; bank < MAX_BANKS; bank++) {
                bt = timings->bank[bank].io_2410;
                if (!bt)
                        continue;

                printk(KERN_DEBUG "%s %d: Tacs=%d.%d, Tcos=%d.%d, Tacc=%d.%d, "
                       "Tcoh=%d.%d, Tcah=%d.%d\n", pfx, bank,
                       print_ns(bt->tacs),
                       print_ns(bt->tcos),
                       print_ns(bt->tacc),
                       print_ns(bt->tcoh),
                       print_ns(bt->tcah));
        }
}

/**
 * bank_reg - convert bank number to pointer to the control register.
 * @bank: The IO bank number.
 */
static inline void __iomem *bank_reg(unsigned int bank)
{
        return S3C2410_BANKCON0 + (bank << 2);
}

/**
 * bank_is_io - test whether bank is used for IO
 * @bankcon: The bank control register.
 *
 * This is a simplistic test to see if any BANKCON[x] is not an IO
 * bank. It currently does not take into account whether BWSCON has
 * an illegal width-setting in it, or if the pin connected to nCS[x]
 * is actually being handled as a chip-select.
 */
static inline int bank_is_io(unsigned long bankcon)
{
        return !(bankcon & S3C2410_BANKCON_SDRAM);
}

/**
 * to_div - convert cycle time to divisor
 * @cyc: The cycle time, in 10ths of nanoseconds.
 * @hclk_tns: The cycle time for HCLK, in 10ths of nanoseconds.
 *
 * Convert the given cycle time into the divisor to use to obtain it from
 * HCLK.
*/
static inline unsigned int to_div(unsigned int cyc, unsigned int hclk_tns)
{
        if (cyc == 0)
                return 0;

        return DIV_ROUND_UP(cyc, hclk_tns);
}

/**
 * calc_0124 - calculate divisor control for divisors that do /0, /1. /2 and /4
 * @cyc: The cycle time, in 10ths of nanoseconds.
 * @hclk_tns: The cycle time for HCLK, in 10ths of nanoseconds.
 * @v: Pointer to register to alter.
 * @shift: The shift to get to the control bits.
 *
 * Calculate the divisor, and turn it into the correct control bits to
 * set in the result, @v.
 */
static unsigned int calc_0124(unsigned int cyc, unsigned long hclk_tns,
                              unsigned long *v, int shift)
{
        unsigned int div = to_div(cyc, hclk_tns);
        unsigned long val;

        s3c_freq_iodbg("%s: cyc=%d, hclk=%lu, shift=%d => div %d\n",
                       __func__, cyc, hclk_tns, shift, div);

        switch (div) {
        case 0:
                val = 0;
                break;
        case 1:
                val = 1;
                break;
        case 2:
                val = 2;
                break;
        case 3:
        case 4:
                val = 3;
                break;
        default:
                return -1;
        }

        *v |= val << shift;
        return 0;
}

int calc_tacp(unsigned int cyc, unsigned long hclk, unsigned long *v)
{
        /* Currently no support for Tacp calculations. */
        return 0;
}

/**
 * calc_tacc - calculate divisor control for tacc.
 * @cyc: The cycle time, in 10ths of nanoseconds.
 * @nwait_en: IS nWAIT enabled for this bank.
 * @hclk_tns: The cycle time for HCLK, in 10ths of nanoseconds.
 * @v: Pointer to register to alter.
 *
 * Calculate the divisor control for tACC, taking into account whether
 * the bank has nWAIT enabled. The result is used to modify the value
 * pointed to by @v.
*/
static int calc_tacc(unsigned int cyc, int nwait_en,
                     unsigned long hclk_tns, unsigned long *v)
{
        unsigned int div = to_div(cyc, hclk_tns);
        unsigned long val;

        s3c_freq_iodbg("%s: cyc=%u, nwait=%d, hclk=%lu => div=%u\n",
                       __func__, cyc, nwait_en, hclk_tns, div);

        /* if nWait enabled on an bank, Tacc must be at-least 4 cycles. */
        if (nwait_en && div < 4)
                div = 4;

        switch (div) {
        case 0:
                val = 0;
                break;

        case 1:
        case 2:
        case 3:
        case 4:
                val = div - 1;
                break;

        case 5:
        case 6:
                val = 4;
                break;

        case 7:
        case 8:
                val = 5;
                break;

        case 9:
        case 10:
                val = 6;
                break;

        case 11:
        case 12:
        case 13:
        case 14:
                val = 7;
                break;

        default:
                return -1;
        }

        *v |= val << 8;
        return 0;
}

/**
 * s3c2410_calc_bank - calculate bank timing infromation
 * @cfg: The configuration we need to calculate for.
 * @bt: The bank timing information.
 *
 * Given the cycle timine for a bank @bt, calculate the new BANKCON
 * setting for the @cfg timing. This updates the timing information
 * ready for the cpu frequency change.
 */
static int s3c2410_calc_bank(struct s3c_cpufreq_config *cfg,
                             struct s3c2410_iobank_timing *bt)
{
        unsigned long hclk = cfg->freq.hclk_tns;
        unsigned long res;
        int ret;

        res  = bt->bankcon;
        res &= (S3C2410_BANKCON_SDRAM | S3C2410_BANKCON_PMC16);

        /* tacp: 2,3,4,5 */
        /* tcah: 0,1,2,4 */
        /* tcoh: 0,1,2,4 */
        /* tacc: 1,2,3,4,6,7,10,14 (>4 for nwait) */
        /* tcos: 0,1,2,4 */
        /* tacs: 0,1,2,4 */

        ret  = calc_0124(bt->tacs, hclk, &res, S3C2410_BANKCON_Tacs_SHIFT);
        ret |= calc_0124(bt->tcos, hclk, &res, S3C2410_BANKCON_Tcos_SHIFT);
        ret |= calc_0124(bt->tcah, hclk, &res, S3C2410_BANKCON_Tcah_SHIFT);
        ret |= calc_0124(bt->tcoh, hclk, &res, S3C2410_BANKCON_Tcoh_SHIFT);

        if (ret)
                return -EINVAL;

        ret |= calc_tacp(bt->tacp, hclk, &res);
        ret |= calc_tacc(bt->tacc, bt->nwait_en, hclk, &res);

        if (ret)
                return -EINVAL;

        bt->bankcon = res;
        return 0;
}

static unsigned int tacc_tab[] = {
        [0]     = 1,
        [1]     = 2,
        [2]     = 3,
        [3]     = 4,
        [4]     = 6,
        [5]     = 9,
        [6]     = 10,
        [7]     = 14,
};

/**
 * get_tacc - turn tACC value into cycle time
 * @hclk_tns: The cycle time for HCLK, in 10ths of nanoseconds.
 * @val: The bank timing register value, shifed down.
 */
static unsigned int get_tacc(unsigned long hclk_tns,
                             unsigned long val)
{
        val &= 7;
        return hclk_tns * tacc_tab[val];
}

/**
 * get_0124 - turn 0/1/2/4 divider into cycle time
 * @hclk_tns: The cycle time for HCLK, in 10ths of nanoseconds.
 * @val: The bank timing register value, shifed down.
 */
static unsigned int get_0124(unsigned long hclk_tns,
                             unsigned long val)
{
        val &= 3;
        return hclk_tns * ((val == 3) ? 4 : val);
}

/**
 * s3c2410_iotiming_getbank - turn BANKCON into cycle time information
 * @cfg: The frequency configuration
 * @bt: The bank timing to fill in (uses cached BANKCON)
 *
 * Given the BANKCON setting in @bt and the current frequency settings
 * in @cfg, update the cycle timing information.
 */
void s3c2410_iotiming_getbank(struct s3c_cpufreq_config *cfg,
                              struct s3c2410_iobank_timing *bt)
{
        unsigned long bankcon = bt->bankcon;
        unsigned long hclk = cfg->freq.hclk_tns;

        bt->tcah = get_0124(hclk, bankcon >> S3C2410_BANKCON_Tcah_SHIFT);
        bt->tcoh = get_0124(hclk, bankcon >> S3C2410_BANKCON_Tcoh_SHIFT);
        bt->tcos = get_0124(hclk, bankcon >> S3C2410_BANKCON_Tcos_SHIFT);
        bt->tacs = get_0124(hclk, bankcon >> S3C2410_BANKCON_Tacs_SHIFT);
        bt->tacc = get_tacc(hclk, bankcon >> S3C2410_BANKCON_Tacc_SHIFT);
}

/**
 * s3c2410_iotiming_debugfs - debugfs show io bank timing information
 * @seq: The seq_file to write output to using seq_printf().
 * @cfg: The current configuration.
 * @iob: The IO bank information to decode.
 */
void s3c2410_iotiming_debugfs(struct seq_file *seq,
                              struct s3c_cpufreq_config *cfg,
                              union s3c_iobank *iob)
{
        struct s3c2410_iobank_timing *bt = iob->io_2410;
        unsigned long bankcon = bt->bankcon;
        unsigned long hclk = cfg->freq.hclk_tns;
        unsigned int tacs;
        unsigned int tcos;
        unsigned int tacc;
        unsigned int tcoh;
        unsigned int tcah;

        seq_printf(seq, "BANKCON=0x%08lx\n", bankcon);

        tcah = get_0124(hclk, bankcon >> S3C2410_BANKCON_Tcah_SHIFT);
        tcoh = get_0124(hclk, bankcon >> S3C2410_BANKCON_Tcoh_SHIFT);
        tcos = get_0124(hclk, bankcon >> S3C2410_BANKCON_Tcos_SHIFT);
        tacs = get_0124(hclk, bankcon >> S3C2410_BANKCON_Tacs_SHIFT);
        tacc = get_tacc(hclk, bankcon >> S3C2410_BANKCON_Tacc_SHIFT);

        seq_printf(seq,
                   "\tRead: Tacs=%d.%d, Tcos=%d.%d, Tacc=%d.%d, Tcoh=%d.%d, Tcah=%d.%d\n",
                   print_ns(bt->tacs),
                   print_ns(bt->tcos),
                   print_ns(bt->tacc),
                   print_ns(bt->tcoh),
                   print_ns(bt->tcah));

        seq_printf(seq,
                   "\t Set: Tacs=%d.%d, Tcos=%d.%d, Tacc=%d.%d, Tcoh=%d.%d, Tcah=%d.%d\n",
                   print_ns(tacs),
                   print_ns(tcos),
                   print_ns(tacc),
                   print_ns(tcoh),
                   print_ns(tcah));
}

/**
 * s3c2410_iotiming_calc - Calculate bank timing for frequency change.
 * @cfg: The frequency configuration
 * @iot: The IO timing information to fill out.
 *
 * Calculate the new values for the banks in @iot based on the new
 * frequency information in @cfg. This is then used by s3c2410_iotiming_set()
 * to update the timing when necessary.
 */
int s3c2410_iotiming_calc(struct s3c_cpufreq_config *cfg,
                          struct s3c_iotimings *iot)
{
        struct s3c2410_iobank_timing *bt;
        unsigned long bankcon;
        int bank;
        int ret;

        for (bank = 0; bank < MAX_BANKS; bank++) {
                bankcon = __raw_readl(bank_reg(bank));
                bt = iot->bank[bank].io_2410;

                if (!bt)
                        continue;

                bt->bankcon = bankcon;

                ret = s3c2410_calc_bank(cfg, bt);
                if (ret) {
                        printk(KERN_ERR "%s: cannot calculate bank %d io\n",
                               __func__, bank);
                        goto err;
                }

                s3c_freq_iodbg("%s: bank %d: con=%08lx\n",
                               __func__, bank, bt->bankcon);
        }

        return 0;
 err:
        return ret;
}

/**
 * s3c2410_iotiming_set - set the IO timings from the given setup.
 * @cfg: The frequency configuration
 * @iot: The IO timing information to use.
 *
 * Set all the currently used IO bank timing information generated
 * by s3c2410_iotiming_calc() once the core has validated that all
 * the new values are within permitted bounds.
 */
void s3c2410_iotiming_set(struct s3c_cpufreq_config *cfg,
                          struct s3c_iotimings *iot)
{
        struct s3c2410_iobank_timing *bt;
        int bank;

        /* set the io timings from the specifier */

        for (bank = 0; bank < MAX_BANKS; bank++) {
                bt = iot->bank[bank].io_2410;
                if (!bt)
                        continue;

                __raw_writel(bt->bankcon, bank_reg(bank));
        }
}

/**
 * s3c2410_iotiming_get - Get the timing information from current registers.
 * @cfg: The frequency configuration
 * @timings: The IO timing information to fill out.
 *
 * Calculate the @timings timing information from the current frequency
 * information in @cfg, and the new frequency configur
 * through all the IO banks, reading the state and then updating @iot
 * as necessary.
 *
 * This is used at the moment on initialisation to get the current
 * configuration so that boards do not have to carry their own setup
 * if the timings are correct on initialisation.
 */

int s3c2410_iotiming_get(struct s3c_cpufreq_config *cfg,
                         struct s3c_iotimings *timings)
{
        struct s3c2410_iobank_timing *bt;
        unsigned long bankcon;
        unsigned long bwscon;
        int bank;

        bwscon = __raw_readl(S3C2410_BWSCON);

        /* look through all banks to see what is currently set. */

        for (bank = 0; bank < MAX_BANKS; bank++) {
                bankcon = __raw_readl(bank_reg(bank));

                if (!bank_is_io(bankcon))
                        continue;

                s3c_freq_iodbg("%s: bank %d: con %08lx\n",
                               __func__, bank, bankcon);

                bt = kzalloc(sizeof(struct s3c2410_iobank_timing), GFP_KERNEL);
                if (!bt) {
                        printk(KERN_ERR "%s: no memory for bank\n", __func__);
                        return -ENOMEM;
                }

                /* find out in nWait is enabled for bank. */

                if (bank != 0) {
                        unsigned long tmp  = S3C2410_BWSCON_GET(bwscon, bank);
                        if (tmp & S3C2410_BWSCON_WS)
                                bt->nwait_en = 1;
                }

                timings->bank[bank].io_2410 = bt;
                bt->bankcon = bankcon;

                s3c2410_iotiming_getbank(cfg, bt);
        }

        s3c2410_print_timing("get", timings);
        return 0;
}