ata: separate PATA timings code from libata-core.c

Separate PATA timings code from libata-core.c:

* add PATA_TIMINGS config option and make corresponding PATA
  host drivers (and ATA ACPI code) select it

* move following PATA timings code to libata-pata-timings.c:
  - ata_timing_quantize()
  - ata_timing_merge()
  - ata_timing_find_mode()
  - ata_timing_compute()

* group above functions together in <linux/libata.h>

* include libata-pata-timings.c in the build when PATA_TIMINGS
  config option is enabled

* cover ata_timing_cycle2mode() with CONFIG_ATA_ACPI ifdef (it
  depends on code from libata-core.c and libata-pata-timings.c
  while its only user is ATA ACPI)

Code size savings on m68k arch using (modified) atari_defconfig:

   text    data     bss     dec     hex filename
before:
  39688     573      40   40301    9d6d drivers/ata/libata-core.o
after:
  37820     572      40   38432    9620 drivers/ata/libata-core.o

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 192 insertions, 0 deletions

diff --git a/drivers/ata/libata-pata-timings.c b/drivers/ata/libata-pata-timings.c
new file mode 100644
index 000000000000..af341226cc64
--- /dev/null
+++ b/drivers/ata/libata-pata-timings.c
@@ -0,0 +1,192 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Helper library for PATA timings
+ *
+ *  Copyright 2003-2004 Red Hat, Inc.  All rights reserved.
+ *  Copyright 2003-2004 Jeff Garzik
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/libata.h>
+
+/*
+ * This mode timing computation functionality is ported over from
+ * drivers/ide/ide-timing.h and was originally written by Vojtech Pavlik
+ */
+/*
+ * PIO 0-4, MWDMA 0-2 and UDMA 0-6 timings (in nanoseconds).
+ * These were taken from ATA/ATAPI-6 standard, rev 0a, except
+ * for UDMA6, which is currently supported only by Maxtor drives.
+ *
+ * For PIO 5/6 MWDMA 3/4 see the CFA specification 3.0.
+ */
+
+static const struct ata_timing ata_timing[] = {
+/*	{ XFER_PIO_SLOW, 120, 290, 240, 960, 290, 240, 0,  960,   0 }, */
+	{ XFER_PIO_0,     70, 290, 240, 600, 165, 150, 0,  600,   0 },
+	{ XFER_PIO_1,     50, 290,  93, 383, 125, 100, 0,  383,   0 },
+	{ XFER_PIO_2,     30, 290,  40, 330, 100,  90, 0,  240,   0 },
+	{ XFER_PIO_3,     30,  80,  70, 180,  80,  70, 0,  180,   0 },
+	{ XFER_PIO_4,     25,  70,  25, 120,  70,  25, 0,  120,   0 },
+	{ XFER_PIO_5,     15,  65,  25, 100,  65,  25, 0,  100,   0 },
+	{ XFER_PIO_6,     10,  55,  20,  80,  55,  20, 0,   80,   0 },
+
+	{ XFER_SW_DMA_0, 120,   0,   0,   0, 480, 480, 50, 960,   0 },
+	{ XFER_SW_DMA_1,  90,   0,   0,   0, 240, 240, 30, 480,   0 },
+	{ XFER_SW_DMA_2,  60,   0,   0,   0, 120, 120, 20, 240,   0 },
+
+	{ XFER_MW_DMA_0,  60,   0,   0,   0, 215, 215, 20, 480,   0 },
+	{ XFER_MW_DMA_1,  45,   0,   0,   0,  80,  50, 5,  150,   0 },
+	{ XFER_MW_DMA_2,  25,   0,   0,   0,  70,  25, 5,  120,   0 },
+	{ XFER_MW_DMA_3,  25,   0,   0,   0,  65,  25, 5,  100,   0 },
+	{ XFER_MW_DMA_4,  25,   0,   0,   0,  55,  20, 5,   80,   0 },
+
+/*	{ XFER_UDMA_SLOW,  0,   0,   0,   0,   0,   0, 0,    0, 150 }, */
+	{ XFER_UDMA_0,     0,   0,   0,   0,   0,   0, 0,    0, 120 },
+	{ XFER_UDMA_1,     0,   0,   0,   0,   0,   0, 0,    0,  80 },
+	{ XFER_UDMA_2,     0,   0,   0,   0,   0,   0, 0,    0,  60 },
+	{ XFER_UDMA_3,     0,   0,   0,   0,   0,   0, 0,    0,  45 },
+	{ XFER_UDMA_4,     0,   0,   0,   0,   0,   0, 0,    0,  30 },
+	{ XFER_UDMA_5,     0,   0,   0,   0,   0,   0, 0,    0,  20 },
+	{ XFER_UDMA_6,     0,   0,   0,   0,   0,   0, 0,    0,  15 },
+
+	{ 0xFF }
+};
+
+#define ENOUGH(v, unit)		(((v)-1)/(unit)+1)
+#define EZ(v, unit)		((v)?ENOUGH(((v) * 1000), unit):0)
+
+static void ata_timing_quantize(const struct ata_timing *t,
+				struct ata_timing *q, int T, int UT)
+{
+	q->setup	= EZ(t->setup,       T);
+	q->act8b	= EZ(t->act8b,       T);
+	q->rec8b	= EZ(t->rec8b,       T);
+	q->cyc8b	= EZ(t->cyc8b,       T);
+	q->active	= EZ(t->active,      T);
+	q->recover	= EZ(t->recover,     T);
+	q->dmack_hold	= EZ(t->dmack_hold,  T);
+	q->cycle	= EZ(t->cycle,       T);
+	q->udma		= EZ(t->udma,       UT);
+}
+
+void ata_timing_merge(const struct ata_timing *a, const struct ata_timing *b,
+		      struct ata_timing *m, unsigned int what)
+{
+	if (what & ATA_TIMING_SETUP)
+		m->setup = max(a->setup, b->setup);
+	if (what & ATA_TIMING_ACT8B)
+		m->act8b = max(a->act8b, b->act8b);
+	if (what & ATA_TIMING_REC8B)
+		m->rec8b = max(a->rec8b, b->rec8b);
+	if (what & ATA_TIMING_CYC8B)
+		m->cyc8b = max(a->cyc8b, b->cyc8b);
+	if (what & ATA_TIMING_ACTIVE)
+		m->active = max(a->active, b->active);
+	if (what & ATA_TIMING_RECOVER)
+		m->recover = max(a->recover, b->recover);
+	if (what & ATA_TIMING_DMACK_HOLD)
+		m->dmack_hold = max(a->dmack_hold, b->dmack_hold);
+	if (what & ATA_TIMING_CYCLE)
+		m->cycle = max(a->cycle, b->cycle);
+	if (what & ATA_TIMING_UDMA)
+		m->udma = max(a->udma, b->udma);
+}
+EXPORT_SYMBOL_GPL(ata_timing_merge);
+
+const struct ata_timing *ata_timing_find_mode(u8 xfer_mode)
+{
+	const struct ata_timing *t = ata_timing;
+
+	while (xfer_mode > t->mode)
+		t++;
+
+	if (xfer_mode == t->mode)
+		return t;
+
+	WARN_ONCE(true, "%s: unable to find timing for xfer_mode 0x%x\n",
+			__func__, xfer_mode);
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(ata_timing_find_mode);
+
+int ata_timing_compute(struct ata_device *adev, unsigned short speed,
+		       struct ata_timing *t, int T, int UT)
+{
+	const u16 *id = adev->id;
+	const struct ata_timing *s;
+	struct ata_timing p;
+
+	/*
+	 * Find the mode.
+	 */
+	s = ata_timing_find_mode(speed);
+	if (!s)
+		return -EINVAL;
+
+	memcpy(t, s, sizeof(*s));
+
+	/*
+	 * If the drive is an EIDE drive, it can tell us it needs extended
+	 * PIO/MW_DMA cycle timing.
+	 */
+
+	if (id[ATA_ID_FIELD_VALID] & 2) {	/* EIDE drive */
+		memset(&p, 0, sizeof(p));
+
+		if (speed >= XFER_PIO_0 && speed < XFER_SW_DMA_0) {
+			if (speed <= XFER_PIO_2)
+				p.cycle = p.cyc8b = id[ATA_ID_EIDE_PIO];
+			else if ((speed <= XFER_PIO_4) ||
+				 (speed == XFER_PIO_5 && !ata_id_is_cfa(id)))
+				p.cycle = p.cyc8b = id[ATA_ID_EIDE_PIO_IORDY];
+		} else if (speed >= XFER_MW_DMA_0 && speed <= XFER_MW_DMA_2)
+			p.cycle = id[ATA_ID_EIDE_DMA_MIN];
+
+		ata_timing_merge(&p, t, t, ATA_TIMING_CYCLE | ATA_TIMING_CYC8B);
+	}
+
+	/*
+	 * Convert the timing to bus clock counts.
+	 */
+
+	ata_timing_quantize(t, t, T, UT);
+
+	/*
+	 * Even in DMA/UDMA modes we still use PIO access for IDENTIFY,
+	 * S.M.A.R.T * and some other commands. We have to ensure that the
+	 * DMA cycle timing is slower/equal than the fastest PIO timing.
+	 */
+
+	if (speed > XFER_PIO_6) {
+		ata_timing_compute(adev, adev->pio_mode, &p, T, UT);
+		ata_timing_merge(&p, t, t, ATA_TIMING_ALL);
+	}
+
+	/*
+	 * Lengthen active & recovery time so that cycle time is correct.
+	 */
+
+	if (t->act8b + t->rec8b < t->cyc8b) {
+		t->act8b += (t->cyc8b - (t->act8b + t->rec8b)) / 2;
+		t->rec8b = t->cyc8b - t->act8b;
+	}
+
+	if (t->active + t->recover < t->cycle) {
+		t->active += (t->cycle - (t->active + t->recover)) / 2;
+		t->recover = t->cycle - t->active;
+	}
+
+	/*
+	 * In a few cases quantisation may produce enough errors to
+	 * leave t->cycle too low for the sum of active and recovery
+	 * if so we must correct this.
+	 */
+	if (t->active + t->recover > t->cycle)
+		t->cycle = t->active + t->recover;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ata_timing_compute);