linux/drivers/ide/ide-timings.c
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   1/*
   2 *  Copyright (c) 1999-2001 Vojtech Pavlik
   3 *  Copyright (c) 2007-2008 Bartlomiej Zolnierkiewicz
   4 *
   5 * This program is free software; you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License as published by
   7 * the Free Software Foundation; either version 2 of the License, or
   8 * (at your option) any later version.
   9 *
  10 * This program is distributed in the hope that it will be useful,
  11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 * GNU General Public License for more details.
  14 *
  15 * You should have received a copy of the GNU General Public License
  16 * along with this program; if not, write to the Free Software
  17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  18 *
  19 * Should you need to contact me, the author, you can do so either by
  20 * e-mail - mail your message to <vojtech@ucw.cz>, or by paper mail:
  21 * Vojtech Pavlik, Simunkova 1594, Prague 8, 182 00 Czech Republic
  22 */
  23
  24#include <linux/kernel.h>
  25#include <linux/ide.h>
  26#include <linux/module.h>
  27
  28/*
  29 * PIO 0-5, MWDMA 0-2 and UDMA 0-6 timings (in nanoseconds).
  30 * These were taken from ATA/ATAPI-6 standard, rev 0a, except
  31 * for PIO 5, which is a nonstandard extension and UDMA6, which
  32 * is currently supported only by Maxtor drives.
  33 */
  34
  35static struct ide_timing ide_timing[] = {
  36
  37        { XFER_UDMA_6,     0,   0,   0,   0,   0,   0,   0,  15 },
  38        { XFER_UDMA_5,     0,   0,   0,   0,   0,   0,   0,  20 },
  39        { XFER_UDMA_4,     0,   0,   0,   0,   0,   0,   0,  30 },
  40        { XFER_UDMA_3,     0,   0,   0,   0,   0,   0,   0,  45 },
  41
  42        { XFER_UDMA_2,     0,   0,   0,   0,   0,   0,   0,  60 },
  43        { XFER_UDMA_1,     0,   0,   0,   0,   0,   0,   0,  80 },
  44        { XFER_UDMA_0,     0,   0,   0,   0,   0,   0,   0, 120 },
  45
  46        { XFER_MW_DMA_4,  25,   0,   0,   0,  55,  20,  80,   0 },
  47        { XFER_MW_DMA_3,  25,   0,   0,   0,  65,  25, 100,   0 },
  48        { XFER_MW_DMA_2,  25,   0,   0,   0,  70,  25, 120,   0 },
  49        { XFER_MW_DMA_1,  45,   0,   0,   0,  80,  50, 150,   0 },
  50        { XFER_MW_DMA_0,  60,   0,   0,   0, 215, 215, 480,   0 },
  51
  52        { XFER_SW_DMA_2,  60,   0,   0,   0, 120, 120, 240,   0 },
  53        { XFER_SW_DMA_1,  90,   0,   0,   0, 240, 240, 480,   0 },
  54        { XFER_SW_DMA_0, 120,   0,   0,   0, 480, 480, 960,   0 },
  55
  56        { XFER_PIO_6,     10,  55,  20,  80,  55,  20,  80,   0 },
  57        { XFER_PIO_5,     15,  65,  25, 100,  65,  25, 100,   0 },
  58        { XFER_PIO_4,     25,  70,  25, 120,  70,  25, 120,   0 },
  59        { XFER_PIO_3,     30,  80,  70, 180,  80,  70, 180,   0 },
  60
  61        { XFER_PIO_2,     30, 290,  40, 330, 100,  90, 240,   0 },
  62        { XFER_PIO_1,     50, 290,  93, 383, 125, 100, 383,   0 },
  63        { XFER_PIO_0,     70, 290, 240, 600, 165, 150, 600,   0 },
  64
  65        { XFER_PIO_SLOW, 120, 290, 240, 960, 290, 240, 960,   0 },
  66
  67        { 0xff }
  68};
  69
  70struct ide_timing *ide_timing_find_mode(u8 speed)
  71{
  72        struct ide_timing *t;
  73
  74        for (t = ide_timing; t->mode != speed; t++)
  75                if (t->mode == 0xff)
  76                        return NULL;
  77        return t;
  78}
  79EXPORT_SYMBOL_GPL(ide_timing_find_mode);
  80
  81u16 ide_pio_cycle_time(ide_drive_t *drive, u8 pio)
  82{
  83        u16 *id = drive->id;
  84        struct ide_timing *t = ide_timing_find_mode(XFER_PIO_0 + pio);
  85        u16 cycle = 0;
  86
  87        if (id[ATA_ID_FIELD_VALID] & 2) {
  88                if (ata_id_has_iordy(drive->id))
  89                        cycle = id[ATA_ID_EIDE_PIO_IORDY];
  90                else
  91                        cycle = id[ATA_ID_EIDE_PIO];
  92
  93                /* conservative "downgrade" for all pre-ATA2 drives */
  94                if (pio < 3 && cycle < t->cycle)
  95                        cycle = 0; /* use standard timing */
  96
  97                /* Use the standard timing for the CF specific modes too */
  98                if (pio > 4 && ata_id_is_cfa(id))
  99                        cycle = 0;
 100        }
 101
 102        return cycle ? cycle : t->cycle;
 103}
 104EXPORT_SYMBOL_GPL(ide_pio_cycle_time);
 105
 106#define ENOUGH(v, unit)         (((v) - 1) / (unit) + 1)
 107#define EZ(v, unit)             ((v) ? ENOUGH(v, unit) : 0)
 108
 109static void ide_timing_quantize(struct ide_timing *t, struct ide_timing *q,
 110                                int T, int UT)
 111{
 112        q->setup   = EZ(t->setup   * 1000,  T);
 113        q->act8b   = EZ(t->act8b   * 1000,  T);
 114        q->rec8b   = EZ(t->rec8b   * 1000,  T);
 115        q->cyc8b   = EZ(t->cyc8b   * 1000,  T);
 116        q->active  = EZ(t->active  * 1000,  T);
 117        q->recover = EZ(t->recover * 1000,  T);
 118        q->cycle   = EZ(t->cycle   * 1000,  T);
 119        q->udma    = EZ(t->udma    * 1000, UT);
 120}
 121
 122void ide_timing_merge(struct ide_timing *a, struct ide_timing *b,
 123                      struct ide_timing *m, unsigned int what)
 124{
 125        if (what & IDE_TIMING_SETUP)
 126                m->setup   = max(a->setup,   b->setup);
 127        if (what & IDE_TIMING_ACT8B)
 128                m->act8b   = max(a->act8b,   b->act8b);
 129        if (what & IDE_TIMING_REC8B)
 130                m->rec8b   = max(a->rec8b,   b->rec8b);
 131        if (what & IDE_TIMING_CYC8B)
 132                m->cyc8b   = max(a->cyc8b,   b->cyc8b);
 133        if (what & IDE_TIMING_ACTIVE)
 134                m->active  = max(a->active,  b->active);
 135        if (what & IDE_TIMING_RECOVER)
 136                m->recover = max(a->recover, b->recover);
 137        if (what & IDE_TIMING_CYCLE)
 138                m->cycle   = max(a->cycle,   b->cycle);
 139        if (what & IDE_TIMING_UDMA)
 140                m->udma    = max(a->udma,    b->udma);
 141}
 142EXPORT_SYMBOL_GPL(ide_timing_merge);
 143
 144int ide_timing_compute(ide_drive_t *drive, u8 speed,
 145                       struct ide_timing *t, int T, int UT)
 146{
 147        u16 *id = drive->id;
 148        struct ide_timing *s, p;
 149
 150        /*
 151         * Find the mode.
 152         */
 153        s = ide_timing_find_mode(speed);
 154        if (s == NULL)
 155                return -EINVAL;
 156
 157        /*
 158         * Copy the timing from the table.
 159         */
 160        *t = *s;
 161
 162        /*
 163         * If the drive is an EIDE drive, it can tell us it needs extended
 164         * PIO/MWDMA cycle timing.
 165         */
 166        if (id[ATA_ID_FIELD_VALID] & 2) {       /* EIDE drive */
 167                memset(&p, 0, sizeof(p));
 168
 169                if (speed >= XFER_PIO_0 && speed < XFER_SW_DMA_0) {
 170                        if (speed <= XFER_PIO_2)
 171                                p.cycle = p.cyc8b = id[ATA_ID_EIDE_PIO];
 172                        else if ((speed <= XFER_PIO_4) ||
 173                                 (speed == XFER_PIO_5 && !ata_id_is_cfa(id)))
 174                                p.cycle = p.cyc8b = id[ATA_ID_EIDE_PIO_IORDY];
 175                } else if (speed >= XFER_MW_DMA_0 && speed <= XFER_MW_DMA_2)
 176                        p.cycle = id[ATA_ID_EIDE_DMA_MIN];
 177
 178                ide_timing_merge(&p, t, t, IDE_TIMING_CYCLE | IDE_TIMING_CYC8B);
 179        }
 180
 181        /*
 182         * Convert the timing to bus clock counts.
 183         */
 184        ide_timing_quantize(t, t, T, UT);
 185
 186        /*
 187         * Even in DMA/UDMA modes we still use PIO access for IDENTIFY,
 188         * S.M.A.R.T and some other commands. We have to ensure that the
 189         * DMA cycle timing is slower/equal than the current PIO timing.
 190         */
 191        if (speed >= XFER_SW_DMA_0) {
 192                ide_timing_compute(drive, drive->pio_mode, &p, T, UT);
 193                ide_timing_merge(&p, t, t, IDE_TIMING_ALL);
 194        }
 195
 196        /*
 197         * Lengthen active & recovery time so that cycle time is correct.
 198         */
 199        if (t->act8b + t->rec8b < t->cyc8b) {
 200                t->act8b += (t->cyc8b - (t->act8b + t->rec8b)) / 2;
 201                t->rec8b = t->cyc8b - t->act8b;
 202        }
 203
 204        if (t->active + t->recover < t->cycle) {
 205                t->active += (t->cycle - (t->active + t->recover)) / 2;
 206                t->recover = t->cycle - t->active;
 207        }
 208
 209        return 0;
 210}
 211EXPORT_SYMBOL_GPL(ide_timing_compute);
 212
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