patch-1.3.21 linux/drivers/block/triton.c

• Lines: 353
• Date: Mon Aug 28 09:19:32 1995
• Orig file: v1.3.20/linux/drivers/block/triton.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.20/linux/drivers/block/triton.c linux/drivers/block/triton.c
@@ -0,0 +1,352 @@
+/*
+ *  linux/drivers/block/triton.c	Version 1.00  Aug 26, 1995
+ *
+ *  Copyright (c) 1995  Mark Lord
+ *  May be copied or modified under the terms of the GNU General Public License
+ */
+
+/*
+ * This module provides support for the Bus Master IDE DMA function
+ * of the Intel PCI Triton chipset (82371FB).
+ *
+ * DMA is currently supported only for hard disk drives (not cdroms).
+ *
+ * Support for cdroms will likely be added at a later date,
+ * after broader experience has been obtained with hard disks.
+ *
+ * Up to four drives may be enabled for DMA, and the Triton chipset will
+ * (hopefully) arbitrate the PCI bus among them.  Note that the 82371FB chip
+ * provides a single "line buffer" for the BM IDE function, so performance of
+ * multiple (two) drives doing DMA simultaneously will suffer somewhat,
+ * as they contest for that resource bottleneck.  This is handled transparently
+ * inside the 82371FB chip.
+ *
+ * By default, DMA support is prepared for use, but is currently enabled only
+ * for drives which support multi-word DMA mode2 (mword2), or which are
+ * recognized as "good" (see table below).  Drives with only mode0 or mode1
+ * (single or multi) DMA should also work with this chipset/driver (eg. MC2112A)
+ * but are not enabled by default.  Use "hdparm -i" to view supported modes
+ * for a given drive.
+ *
+ * The hdparm-2.4 (or later) utility can be used for manually enabling/disabling
+ * DMA support, but must be (re-)compiled against this kernel version or later.
+ *
+ * To enable DMA, use "hdparm -d1 /dev/hd?" on a per-drive basis after booting.
+ * If problems arise, ide.c will disable DMA operation after a few retries.
+ * This error recovery mechanism works and has been extremely well exercised.
+ *
+ * IDE drives, depending on their vintage, may support several different modes
+ * of DMA operation.  The boot-time modes are indicated with a "*" in
+ * the "hdparm -i" listing, and can be changed with *knowledgeable* use of
+ * the "hdparm -X" feature.  There is seldom a need to do this, as drives
+ * normally power-up with their "best" PIO/DMA modes enabled.
+ *
+ * Testing was done with an ASUS P55TP4XE/100 system and the following drives:
+ *
+ *   Quantum Fireball 1080A (1Gig w/83kB buffer), DMA mode2, PIO mode4.
+ *	- DMA mode2 works fine (7.4MB/sec), despite the tiny on-drive buffer.
+ *	- This drive also does PIO mode4, slightly slower than DMA mode2.
+ *
+ *   Micropolis MC2112A (1Gig w/512kB buffer), drive pre-dates EIDE, ATA2.
+ *	- DMA works fine (2.2MB/sec), probably due to the large on-drive buffer.
+ *	- This older drive can also be tweaked for fastPIO (3,7MB/sec) by using
+ *	  maximum clock settings (5,4) and setting all flags except prefetch.
+ *
+ *   Western Digital AC31000H (1Gig w/128kB buffer), DMA mode1, PIO mode3.
+ *	- DMA does not work reliably.  The drive appears to be somewhat tardy
+ *	  in deasserting DMARQ at the end of a sector.  This is evident in
+ *	  the observation that WRITEs work most of the time, depending on
+ *	  cache-buffer occupancy, but multi-sector reads seldom work.
+ *
+ * Drives like the AC31000H could likely be made to work if all DMA were done
+ * one sector at a time, but that would likely negate any advantage over PIO.
+ *
+ * If you have any drive models add, email your results to:  mlord@bnr.ca
+ * Keep an eye on your /var/adm/messages for "DMA disabled" messages.
+ */
+#define _TRITON_C
+#include <linux/config.h>
+#ifndef CONFIG_BLK_DEV_TRITON
+#define CONFIG_BLK_DEV_TRITON y
+#endif
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/mm.h>
+#include <linux/ioport.h>
+#include <linux/interrupt.h>
+#include <linux/blkdev.h>
+#include <linux/hdreg.h>
+#include <linux/pci.h>
+#include <linux/bios32.h>
+#include <asm/io.h>
+
+#include "ide.h"
+
+/*
+ * good_dma_drives() lists the model names (from "hdparm -i")
+ * of drives which do not support mword2 DMA but which are
+ * known to work fine with this interface under Linux.
+ */
+const char *good_dma_drives[] = {"Micropolis 2112A"};
+
+/*
+ * Our Physical Region Descriptor (PRD) table should be large enough
+ * to handle the biggest I/O request we are likely to see.  Since requests
+ * can have no more than 256 sectors, and since the typical blocksize is
+ * two sectors, we can get by with a limit of 128 entries here for the
+ * usual worst case.  Most requests seem to include some contiguous blocks,
+ * further reducing the number of table entries required.
+ *
+ * Note that the driver reverts to PIO mode for individual requests that exceed
+ * this limit (possible with 512 byte blocksizes, eg. MSDOS f/s), so handling
+ * 100% of all crazy scenarios here is not necessary.
+ */
+#define PRD_ENTRIES	128	/* max memory area count per DMA */
+
+/*
+ * dma_intr() is the handler for disk read/write DMA interrupts
+ */
+static void dma_intr (ide_drive_t *drive)
+{
+	byte stat, dma_stat;
+	int i;
+	struct request *rq = HWGROUP(drive)->rq;
+	unsigned short dma_base = HWIF(drive)->dma_base;
+
+	dma_stat = inb(dma_base+2);	/* get DMA status */
+	outb(inb(dma_base)&~1, dma_base);	/* stop DMA operation */
+	stat = GET_STAT();
+	if (OK_STAT(stat,DRIVE_READY,drive->bad_wstat|DRQ_STAT)) {
+		if ((dma_stat & 7) == 4) {	/* verify good DMA status */
+			rq = HWGROUP(drive)->rq;
+			for (i = rq->nr_sectors; i > 0;) {
+				i -= rq->current_nr_sectors;
+				ide_end_request(1, HWGROUP(drive));
+			}
+			IDE_DO_REQUEST;
+			return;
+		}
+		printk("%s: bad DMA status: 0x%02x\n", drive->name, dma_stat);
+	}
+	sti();
+	if (!ide_error(drive, "dma_intr", stat))
+		IDE_DO_REQUEST;
+}
+
+/*
+ * build_dmatable() prepares a dma request.
+ * Returns 0 if all went okay, returns 1 otherwise.
+ */
+static int build_dmatable (ide_drive_t *drive)
+{
+	struct request *rq = HWGROUP(drive)->rq;
+	struct buffer_head *bh = rq->bh;
+	unsigned long size, addr, *table = HWIF(drive)->dmatable;
+	unsigned int count = 0;
+
+	do {
+		/*
+		 * Determine addr and size of next buffer area.  We assume that
+		 * individual virtual buffers are always composed linearly in
+		 * physical memory.  For example, we assume that any 8kB buffer
+		 * is always composed of two adjacent physical 4kB pages rather
+		 * than two possibly non-adjacent physical 4kB pages.
+		 */
+		if (bh == NULL) {  /* paging requests have (rq->bh == NULL) */
+			addr = virt_to_bus (rq->buffer);
+			size = rq->nr_sectors << 9;
+		} else {
+			/* group sequential buffers into one large buffer */
+			addr = virt_to_bus (bh->b_data);
+			size = bh->b_size;
+			while ((bh = bh->b_reqnext) != NULL) {
+				if ((addr + size) != virt_to_bus (bh->b_data))
+					break;
+				size += bh->b_size;
+			}
+		}
+
+		/*
+		 * Fill in the dma table, without crossing any 64kB boundaries.
+		 * We assume 16-bit alignment of all blocks.
+		 */
+		while (size) {
+			if (++count >= PRD_ENTRIES) {
+				printk("%s: DMA table too small\n", drive->name);
+				return 1; /* revert to PIO for this request */
+			} else {
+				unsigned long bcount = 0x10000 - (addr & 0xffff);
+				if (bcount > size)
+					bcount = size;
+				*table++ = addr;
+				*table++ = bcount;
+				addr += bcount;
+				size -= bcount;
+			}
+		}
+	} while (bh != NULL);
+	if (count) {
+		*--table |= 0x80000000;	/* set End-Of-Table (EOT) bit */
+		return 0;
+	}
+	printk("%s: empty DMA table?\n", drive->name);
+	return 1;	/* let the PIO routines handle this weirdness */
+}
+
+/*
+ * triton_dmaproc() initiates/aborts DMA read/write operations on a drive.
+ *
+ * The caller is assumed to have selected the drive and programmed the drive's
+ * sector address using CHS or LBA.  All that remains is to prepare for DMA
+ * and then issue the actual read/write DMA/PIO command to the drive.
+ *
+ * Returns 0 if all went well.
+ * Returns 1 if DMA read/write could not be started, in which case
+ * the caller should revert to PIO for the current request.
+ */
+static int triton_dmaproc (ide_dma_action_t func, ide_drive_t *drive)
+{
+	const char **list;
+	unsigned long dma_base = HWIF(drive)->dma_base;
+
+	if (func == ide_dma_abort) {
+		outb(inb(dma_base)&~1, dma_base);	/* stop DMA */
+		return 0;
+	}
+	if (func == ide_dma_check) {
+		struct hd_driveid *id = drive->id;
+		if (id && (id->capability & 1)) {
+			/* Enable DMA on any drive that supports mword2 DMA */
+			if ((id->field_valid & 2) && (id->dma_mword & 0x404) == 0x404) {
+				drive->using_dma = 1;
+				return 0;		/* DMA enabled */
+			}
+			/* Consult the list of known "good" drives */
+			list = good_dma_drives;
+			while (*list) {
+				if (!strcmp(*list++,id->model)) {
+					drive->using_dma = 1;
+					return 0;	/* DMA enabled */
+				}
+			}
+		}
+		return 1;	/* DMA not enabled */
+	}
+	if (build_dmatable (drive))
+		return 1;
+	outl(virt_to_bus (HWIF(drive)->dmatable), dma_base + 4); /* PRD table */
+	outb((!func) << 3, dma_base);			/* specify r/w */
+	outb(0x26, dma_base+2);				/* clear status bits */
+	ide_set_handler (drive, &dma_intr);		/* issue cmd to drive */
+	OUT_BYTE(func ? WIN_WRITEDMA : WIN_READDMA, IDE_COMMAND_REG);
+	outb(inb(dma_base)|1, dma_base);			/* begin DMA */
+	return 0;
+}
+
+/*
+ * print_triton_drive_flags() displays the currently programmed options
+ * in the Triton chipset for a given drive.
+ *
+ *	If fastDMA  is "no", then slow ISA timings are used for DMA data xfers.
+ *	If fastPIO  is "no", then slow ISA timings are used for PIO data xfers.
+ *	If IORDY    is "no", then IORDY is assumed to always be asserted.
+ *	If PreFetch is "no", then data pre-fetch/post are not used.
+ *
+ * When "fastPIO" and/or "fastDMA" are "yes", then faster PCI timings and
+ * back-to-back 16-bit data transfers are enabled, using the sample_CLKs
+ * and recovery_CLKs (PCI clock cycles) timing parameters for that interface.
+ */
+static void print_triton_drive_flags (unsigned int unit, byte flags)
+{
+	printk("         %s ", unit ? "slave :" : "master:");
+	printk( "fastDMA=%s",	(flags&9)	? "on " : "off");
+	printk(" PreFetch=%s",	(flags&4)	? "on " : "off");
+	printk(" IORDY=%s",	(flags&2)	? "on " : "off");
+	printk(" fastPIO=%s\n",	((flags&9)==1)	? "on " : "off");
+}
+
+/*
+ * ide_init_triton() uses the PCI BIOS to scan for a Triton i82371FB chip,
+ * and prepares the IDE driver for DMA operation if one is found.
+ * This routine is called from ide.c during driver initialization.
+ */
+void ide_init_triton (ide_hwif_t  hwifs[])
+{
+	int rc = 0, h;
+	unsigned short bmiba, pcicmd;
+	unsigned int timings;
+	unsigned char bus, fn;
+
+	if (pcibios_find_device (PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82371, 0, &bus, &fn))
+		goto quit;
+	++fn;	/* IDE is second function on this chip */
+
+	/*
+	 * See if IDE and BM-DMA features are enabled:
+	 */
+	if ((rc = pcibios_read_config_word(bus, fn, 0x04, &pcicmd)))
+		goto quit;
+	if ((pcicmd & 5) != 5) {
+		if ((pcicmd & 1) == 0)
+			printk("ide: Triton IDE ports are not enabled\n");
+		else
+			printk("ide: Triton BM-DMA feature is not enabled\n");
+		goto quit;
+	}
+#if 0
+	(void) pcibios_write_config_word(bus, fn, 0x42, 0x8037); /* for my MC2112A */
+#endif
+	/*
+	 * See if ide port(s) are enabled
+	 */
+	if ((rc = pcibios_read_config_dword(bus, fn, 0x40, &timings)))
+		goto quit;
+	if (!(timings & 0x80008000)) {
+		printk("ide: Triton IDE ports are not enabled\n");
+		goto quit;
+	}
+	printk("ide: Triton BM-IDE on PCI bus %d function %d\n", bus, fn);
+
+	/*
+	 * Get the bmiba base address
+	 */
+	if ((rc = pcibios_read_config_word(bus, fn, 0x20, &bmiba)))
+		goto quit;
+	bmiba &= 0xfff0;	/* extract port base address */
+
+	/*
+	 * Save the dma_base port addr for each interface
+	 */
+	for (h = 0; h < MAX_HWIFS; ++h) {
+		ide_hwif_t *hwif = &hwifs[h];
+		unsigned short base, time;
+		if (hwif->io_base == 0x1f0 && (timings & 0x8000)) {
+			time = timings & 0xffff;
+			base = bmiba;
+		} else if (hwif->io_base == 0x170 && (timings & 0x80000000)) {
+			time = timings >> 16;
+			base = bmiba + 8;
+		} else
+			continue;
+		printk("    %s: BusMaster DMA at 0x%04x-0x%04x", hwif->name, base, base+5);
+		if (check_region(base, 6)) {
+			printk(" -- ERROR, PORTS ALREADY IN USE");
+		} else {
+			unsigned long *table;
+			request_region(base, 8, hwif->name);
+			hwif->dma_base  = base;
+			table = ide_alloc(2 * PRD_ENTRIES * sizeof(long), 4096);
+			hwif->dmatable = table;
+			outl((unsigned long) table, base + 4);
+			hwif->dmaproc  = &triton_dmaproc;
+		}
+		printk("\n    %s timing: (0x%04x) sample_CLKs=%d, recovery_CLKs=%d\n",
+		 hwif->name, time, ((~time>>12)&3)+2, ((~time>>8)&3)+1);
+		print_triton_drive_flags (0, time & 0xf);
+		print_triton_drive_flags (1, (time >> 4) & 0xf);
+	}
+
+quit: if (rc) printk("ide: pcibios access failed - %s\n", pcibios_strerror(rc));
+}
+