1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Helper library for PATA timings
4 *
5 * Copyright 2003-2004 Red Hat, Inc. All rights reserved.
6 * Copyright 2003-2004 Jeff Garzik
7 */
8
9#include <linux/kernel.h>
10#include <linux/module.h>
11#include <linux/libata.h>
12
13/*
14 * This mode timing computation functionality is ported over from
15 * drivers/ide/ide-timing.h and was originally written by Vojtech Pavlik
16 */
17/*
18 * PIO 0-4, MWDMA 0-2 and UDMA 0-6 timings (in nanoseconds).
19 * These were taken from ATA/ATAPI-6 standard, rev 0a, except
20 * for UDMA6, which is currently supported only by Maxtor drives.
21 *
22 * For PIO 5/6 MWDMA 3/4 see the CFA specification 3.0.
23 */
24
25static const struct ata_timing ata_timing[] = {
26/* { XFER_PIO_SLOW, 120, 290, 240, 960, 290, 240, 0, 960, 0 }, */
27 { XFER_PIO_0, 70, 290, 240, 600, 165, 150, 0, 600, 0 },
28 { XFER_PIO_1, 50, 290, 93, 383, 125, 100, 0, 383, 0 },
29 { XFER_PIO_2, 30, 290, 40, 330, 100, 90, 0, 240, 0 },
30 { XFER_PIO_3, 30, 80, 70, 180, 80, 70, 0, 180, 0 },
31 { XFER_PIO_4, 25, 70, 25, 120, 70, 25, 0, 120, 0 },
32 { XFER_PIO_5, 15, 65, 25, 100, 65, 25, 0, 100, 0 },
33 { XFER_PIO_6, 10, 55, 20, 80, 55, 20, 0, 80, 0 },
34
35 { XFER_SW_DMA_0, 120, 0, 0, 0, 480, 480, 50, 960, 0 },
36 { XFER_SW_DMA_1, 90, 0, 0, 0, 240, 240, 30, 480, 0 },
37 { XFER_SW_DMA_2, 60, 0, 0, 0, 120, 120, 20, 240, 0 },
38
39 { XFER_MW_DMA_0, 60, 0, 0, 0, 215, 215, 20, 480, 0 },
40 { XFER_MW_DMA_1, 45, 0, 0, 0, 80, 50, 5, 150, 0 },
41 { XFER_MW_DMA_2, 25, 0, 0, 0, 70, 25, 5, 120, 0 },
42 { XFER_MW_DMA_3, 25, 0, 0, 0, 65, 25, 5, 100, 0 },
43 { XFER_MW_DMA_4, 25, 0, 0, 0, 55, 20, 5, 80, 0 },
44
45/* { XFER_UDMA_SLOW, 0, 0, 0, 0, 0, 0, 0, 0, 150 }, */
46 { XFER_UDMA_0, 0, 0, 0, 0, 0, 0, 0, 0, 120 },
47 { XFER_UDMA_1, 0, 0, 0, 0, 0, 0, 0, 0, 80 },
48 { XFER_UDMA_2, 0, 0, 0, 0, 0, 0, 0, 0, 60 },
49 { XFER_UDMA_3, 0, 0, 0, 0, 0, 0, 0, 0, 45 },
50 { XFER_UDMA_4, 0, 0, 0, 0, 0, 0, 0, 0, 30 },
51 { XFER_UDMA_5, 0, 0, 0, 0, 0, 0, 0, 0, 20 },
52 { XFER_UDMA_6, 0, 0, 0, 0, 0, 0, 0, 0, 15 },
53
54 { 0xFF }
55};
56
57#define ENOUGH(v, unit) (((v)-1)/(unit)+1)
58#define EZ(v, unit) ((v)?ENOUGH(((v) * 1000), unit):0)
59
60static void ata_timing_quantize(const struct ata_timing *t,
61 struct ata_timing *q, int T, int UT)
62{
63 q->setup = EZ(t->setup, T);
64 q->act8b = EZ(t->act8b, T);
65 q->rec8b = EZ(t->rec8b, T);
66 q->cyc8b = EZ(t->cyc8b, T);
67 q->active = EZ(t->active, T);
68 q->recover = EZ(t->recover, T);
69 q->dmack_hold = EZ(t->dmack_hold, T);
70 q->cycle = EZ(t->cycle, T);
71 q->udma = EZ(t->udma, UT);
72}
73
74void ata_timing_merge(const struct ata_timing *a, const struct ata_timing *b,
75 struct ata_timing *m, unsigned int what)
76{
77 if (what & ATA_TIMING_SETUP)
78 m->setup = max(a->setup, b->setup);
79 if (what & ATA_TIMING_ACT8B)
80 m->act8b = max(a->act8b, b->act8b);
81 if (what & ATA_TIMING_REC8B)
82 m->rec8b = max(a->rec8b, b->rec8b);
83 if (what & ATA_TIMING_CYC8B)
84 m->cyc8b = max(a->cyc8b, b->cyc8b);
85 if (what & ATA_TIMING_ACTIVE)
86 m->active = max(a->active, b->active);
87 if (what & ATA_TIMING_RECOVER)
88 m->recover = max(a->recover, b->recover);
89 if (what & ATA_TIMING_DMACK_HOLD)
90 m->dmack_hold = max(a->dmack_hold, b->dmack_hold);
91 if (what & ATA_TIMING_CYCLE)
92 m->cycle = max(a->cycle, b->cycle);
93 if (what & ATA_TIMING_UDMA)
94 m->udma = max(a->udma, b->udma);
95}
96EXPORT_SYMBOL_GPL(ata_timing_merge);
97
98const struct ata_timing *ata_timing_find_mode(u8 xfer_mode)
99{
100 const struct ata_timing *t = ata_timing;
101
102 while (xfer_mode > t->mode)
103 t++;
104
105 if (xfer_mode == t->mode)
106 return t;
107
108 WARN_ONCE(true, "%s: unable to find timing for xfer_mode 0x%x\n",
109 __func__, xfer_mode);
110
111 return NULL;
112}
113EXPORT_SYMBOL_GPL(ata_timing_find_mode);
114
115int ata_timing_compute(struct ata_device *adev, unsigned short speed,
116 struct ata_timing *t, int T, int UT)
117{
118 const u16 *id = adev->id;
119 const struct ata_timing *s;
120 struct ata_timing p;
121
122 /*
123 * Find the mode.
124 */
125 s = ata_timing_find_mode(speed);
126 if (!s)
127 return -EINVAL;
128
129 memcpy(to: t, from: s, len: sizeof(*s));
130
131 /*
132 * If the drive is an EIDE drive, it can tell us it needs extended
133 * PIO/MW_DMA cycle timing.
134 */
135
136 if (id[ATA_ID_FIELD_VALID] & 2) { /* EIDE drive */
137 memset(s: &p, c: 0, n: sizeof(p));
138
139 if (speed >= XFER_PIO_0 && speed < XFER_SW_DMA_0) {
140 if (speed <= XFER_PIO_2)
141 p.cycle = p.cyc8b = id[ATA_ID_EIDE_PIO];
142 else if ((speed <= XFER_PIO_4) ||
143 (speed == XFER_PIO_5 && !ata_id_is_cfa(id)))
144 p.cycle = p.cyc8b = id[ATA_ID_EIDE_PIO_IORDY];
145 } else if (speed >= XFER_MW_DMA_0 && speed <= XFER_MW_DMA_2)
146 p.cycle = id[ATA_ID_EIDE_DMA_MIN];
147
148 ata_timing_merge(&p, t, t, ATA_TIMING_CYCLE | ATA_TIMING_CYC8B);
149 }
150
151 /*
152 * Convert the timing to bus clock counts.
153 */
154
155 ata_timing_quantize(t, q: t, T, UT);
156
157 /*
158 * Even in DMA/UDMA modes we still use PIO access for IDENTIFY,
159 * S.M.A.R.T * and some other commands. We have to ensure that the
160 * DMA cycle timing is slower/equal than the fastest PIO timing.
161 */
162
163 if (speed > XFER_PIO_6) {
164 ata_timing_compute(adev, speed: adev->pio_mode, t: &p, T, UT);
165 ata_timing_merge(&p, t, t, ATA_TIMING_ALL);
166 }
167
168 /*
169 * Lengthen active & recovery time so that cycle time is correct.
170 */
171
172 if (t->act8b + t->rec8b < t->cyc8b) {
173 t->act8b += (t->cyc8b - (t->act8b + t->rec8b)) / 2;
174 t->rec8b = t->cyc8b - t->act8b;
175 }
176
177 if (t->active + t->recover < t->cycle) {
178 t->active += (t->cycle - (t->active + t->recover)) / 2;
179 t->recover = t->cycle - t->active;
180 }
181
182 /*
183 * In a few cases quantisation may produce enough errors to
184 * leave t->cycle too low for the sum of active and recovery
185 * if so we must correct this.
186 */
187 if (t->active + t->recover > t->cycle)
188 t->cycle = t->active + t->recover;
189
190 return 0;
191}
192EXPORT_SYMBOL_GPL(ata_timing_compute);
193