drivers/ide/ide-timings.c

   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
  35 static 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_2,  25,   0,   0,   0,  70,  25, 120,   0 },
  47         { XFER_MW_DMA_1,  45,   0,   0,   0,  80,  50, 150,   0 },
  48         { XFER_MW_DMA_0,  60,   0,   0,   0, 215, 215, 480,   0 },
  49
  50         { XFER_SW_DMA_2,  60,   0,   0,   0, 120, 120, 240,   0 },
  51         { XFER_SW_DMA_1,  90,   0,   0,   0, 240, 240, 480,   0 },
  52         { XFER_SW_DMA_0, 120,   0,   0,   0, 480, 480, 960,   0 },
  53
  54         { XFER_PIO_5,     20,  50,  30, 100,  50,  30, 100,   0 },
  55         { XFER_PIO_4,     25,  70,  25, 120,  70,  25, 120,   0 },
  56         { XFER_PIO_3,     30,  80,  70, 180,  80,  70, 180,   0 },
  57
  58         { XFER_PIO_2,     30, 290,  40, 330, 100,  90, 240,   0 },
  59         { XFER_PIO_1,     50, 290,  93, 383, 125, 100, 383,   0 },
  60         { XFER_PIO_0,     70, 290, 240, 600, 165, 150, 600,   0 },
  61
  62         { XFER_PIO_SLOW, 120, 290, 240, 960, 290, 240, 960,   0 },
  63
  64         { 0xff }
  65 };
  66
  67 struct ide_timing *ide_timing_find_mode(u8 speed)
  68 {
  69         struct ide_timing *t;
  70
  71         for (t = ide_timing; t->mode != speed; t++)
  72                 if (t->mode == 0xff)
  73                         return NULL;
  74         return t;
  75 }
  76 EXPORT_SYMBOL_GPL(ide_timing_find_mode);
  77
  78 u16 ide_pio_cycle_time(ide_drive_t *drive, u8 pio)
  79 {
  80         u16 *id = drive->id;
  81         struct ide_timing *t = ide_timing_find_mode(XFER_PIO_0 + pio);
  82         u16 cycle = 0;
  83
  84         if (id[ATA_ID_FIELD_VALID] & 2) {
  85                 if (ata_id_has_iordy(drive->id))
  86                         cycle = id[ATA_ID_EIDE_PIO_IORDY];
  87                 else
  88                         cycle = id[ATA_ID_EIDE_PIO];
  89
  90                 /* conservative "downgrade" for all pre-ATA2 drives */
  91                 if (pio < 3 && cycle < t->cycle)
  92                         cycle = 0; /* use standard timing */
  93         }
  94
  95         return cycle ? cycle : t->cycle;
  96 }
  97 EXPORT_SYMBOL_GPL(ide_pio_cycle_time);
  98
  99 #define ENOUGH(v, unit)         (((v) - 1) / (unit) + 1)
 100 #define EZ(v, unit)             ((v) ? ENOUGH(v, unit) : 0)
 101
 102 static void ide_timing_quantize(struct ide_timing *t, struct ide_timing *q,
 103                                 int T, int UT)
 104 {
 105         q->setup   = EZ(t->setup   * 1000,  T);
 106         q->act8b   = EZ(t->act8b   * 1000,  T);
 107         q->rec8b   = EZ(t->rec8b   * 1000,  T);
 108         q->cyc8b   = EZ(t->cyc8b   * 1000,  T);
 109         q->active  = EZ(t->active  * 1000,  T);
 110         q->recover = EZ(t->recover * 1000,  T);
 111         q->cycle   = EZ(t->cycle   * 1000,  T);
 112         q->udma    = EZ(t->udma    * 1000, UT);
 113 }
 114
 115 void ide_timing_merge(struct ide_timing *a, struct ide_timing *b,
 116                       struct ide_timing *m, unsigned int what)
 117 {
 118         if (what & IDE_TIMING_SETUP)
 119                 m->setup   = max(a->setup,   b->setup);
 120         if (what & IDE_TIMING_ACT8B)
 121                 m->act8b   = max(a->act8b,   b->act8b);
 122         if (what & IDE_TIMING_REC8B)
 123                 m->rec8b   = max(a->rec8b,   b->rec8b);
 124         if (what & IDE_TIMING_CYC8B)
 125                 m->cyc8b   = max(a->cyc8b,   b->cyc8b);
 126         if (what & IDE_TIMING_ACTIVE)
 127                 m->active  = max(a->active,  b->active);
 128         if (what & IDE_TIMING_RECOVER)
 129                 m->recover = max(a->recover, b->recover);
 130         if (what & IDE_TIMING_CYCLE)
 131                 m->cycle   = max(a->cycle,   b->cycle);
 132         if (what & IDE_TIMING_UDMA)
 133                 m->udma    = max(a->udma,    b->udma);
 134 }
 135 EXPORT_SYMBOL_GPL(ide_timing_merge);
 136
 137 int ide_timing_compute(ide_drive_t *drive, u8 speed,
 138                        struct ide_timing *t, int T, int UT)
 139 {
 140         u16 *id = drive->id;
 141         struct ide_timing *s, p;
 142
 143         /*
 144          * Find the mode.
 145          */
 146         s = ide_timing_find_mode(speed);
 147         if (s == NULL)
 148                 return -EINVAL;
 149
 150         /*
 151          * Copy the timing from the table.
 152          */
 153         *t = *s;
 154
 155         /*
 156          * If the drive is an EIDE drive, it can tell us it needs extended
 157          * PIO/MWDMA cycle timing.
 158          */
 159         if (id[ATA_ID_FIELD_VALID] & 2) {       /* EIDE drive */
 160                 memset(&p, 0, sizeof(p));
 161
 162                 if (speed <= XFER_PIO_2)
 163                         p.cycle = p.cyc8b = id[ATA_ID_EIDE_PIO];
 164                 else if (speed <= XFER_PIO_5)
 165                         p.cycle = p.cyc8b = id[ATA_ID_EIDE_PIO_IORDY];
 166                 else if (speed >= XFER_MW_DMA_0 && speed <= XFER_MW_DMA_2)
 167                         p.cycle = id[ATA_ID_EIDE_DMA_MIN];
 168
 169                 ide_timing_merge(&p, t, t, IDE_TIMING_CYCLE | IDE_TIMING_CYC8B);
 170         }
 171
 172         /*
 173          * Convert the timing to bus clock counts.
 174          */
 175         ide_timing_quantize(t, t, T, UT);
 176
 177         /*
 178          * Even in DMA/UDMA modes we still use PIO access for IDENTIFY,
 179          * S.M.A.R.T and some other commands. We have to ensure that the
 180          * DMA cycle timing is slower/equal than the fastest PIO timing.
 181          */
 182         if (speed >= XFER_SW_DMA_0) {
 183                 u8 pio = ide_get_best_pio_mode(drive, 255, 5);
 184                 ide_timing_compute(drive, XFER_PIO_0 + pio, &p, T, UT);
 185                 ide_timing_merge(&p, t, t, IDE_TIMING_ALL);
 186         }
 187
 188         /*
 189          * Lengthen active & recovery time so that cycle time is correct.
 190          */
 191         if (t->act8b + t->rec8b < t->cyc8b) {
 192                 t->act8b += (t->cyc8b - (t->act8b + t->rec8b)) / 2;
 193                 t->rec8b = t->cyc8b - t->act8b;
 194         }
 195
 196         if (t->active + t->recover < t->cycle) {
 197                 t->active += (t->cycle - (t->active + t->recover)) / 2;
 198                 t->recover = t->cycle - t->active;
 199         }
 200
 201         return 0;
 202 }
 203 EXPORT_SYMBOL_GPL(ide_timing_compute);