Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 842 insertions, 0 deletions

diff --git a/drivers/ide/cris/ide-v10.c b/drivers/ide/cris/ide-v10.c
new file mode 100644
index 0000000..5b40220
--- /dev/null
+++ b/drivers/ide/cris/ide-v10.c
@@ -0,0 +1,842 @@
+/* $Id: ide.c,v 1.4 2004/10/12 07:55:48 starvik Exp $
+ *
+ * Etrax specific IDE functions, like init and PIO-mode setting etc.
+ * Almost the entire ide.c is used for the rest of the Etrax ATA driver.
+ * Copyright (c) 2000-2004 Axis Communications AB
+ *
+ * Authors:    Bjorn Wesen        (initial version)
+ *             Mikael Starvik     (pio setup stuff, Linux 2.6 port)
+ */
+
+/* Regarding DMA:
+ *
+ * There are two forms of DMA - "DMA handshaking" between the interface and the drive,
+ * and DMA between the memory and the interface. We can ALWAYS use the latter, since it's
+ * something built-in in the Etrax. However only some drives support the DMA-mode handshaking
+ * on the ATA-bus. The normal PC driver and Triton interface disables memory-if DMA when the
+ * device can't do DMA handshaking for some stupid reason. We don't need to do that.
+ */
+
+#undef REALLY_SLOW_IO           /* most systems can safely undef this */
+
+#include <linux/config.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/blkdev.h>
+#include <linux/hdreg.h>
+#include <linux/ide.h>
+#include <linux/init.h>
+#include <linux/scatterlist.h>
+
+#include <asm/io.h>
+#include <asm/arch/svinto.h>
+#include <asm/dma.h>
+
+/* number of Etrax DMA descriptors */
+#define MAX_DMA_DESCRS 64
+
+/* number of times to retry busy-flags when reading/writing IDE-registers
+ * this can't be too high because a hung harddisk might cause the watchdog
+ * to trigger (sometimes INB and OUTB are called with irq's disabled)
+ */
+
+#define IDE_REGISTER_TIMEOUT 300
+
+static int e100_read_command = 0;
+
+#define LOWDB(x)
+#define D(x)
+
+static int e100_ide_build_dmatable (ide_drive_t *drive);
+static ide_startstop_t etrax_dma_intr (ide_drive_t *drive);
+
+void
+etrax100_ide_outw(unsigned short data, unsigned long reg) {
+	int timeleft;
+	LOWDB(printk("ow: data 0x%x, reg 0x%x\n", data, reg));
+
+	/* note the lack of handling any timeouts. we stop waiting, but we don't
+	 * really notify anybody.
+	 */
+
+	timeleft = IDE_REGISTER_TIMEOUT;
+	/* wait for busy flag */
+	while(timeleft && (*R_ATA_STATUS_DATA & IO_MASK(R_ATA_STATUS_DATA, busy)))
+		timeleft--;
+
+	/*
+	 * Fall through at a timeout, so the ongoing command will be
+	 * aborted by the write below, which is expected to be a dummy
+	 * command to the command register.  This happens when a faulty
+	 * drive times out on a command.  See comment on timeout in
+	 * INB.
+	 */
+	if(!timeleft)
+		printk("ATA timeout reg 0x%lx := 0x%x\n", reg, data);
+
+	*R_ATA_CTRL_DATA = reg | data; /* write data to the drive's register */
+
+	timeleft = IDE_REGISTER_TIMEOUT;
+	/* wait for transmitter ready */
+	while(timeleft && !(*R_ATA_STATUS_DATA &
+			    IO_MASK(R_ATA_STATUS_DATA, tr_rdy)))
+		timeleft--;
+}
+
+void
+etrax100_ide_outb(unsigned char data, unsigned long reg)
+{
+	etrax100_ide_outw(data, reg);
+}
+
+void
+etrax100_ide_outbsync(ide_drive_t *drive, u8 addr, unsigned long port)
+{
+	etrax100_ide_outw(addr, port);
+}
+
+unsigned short
+etrax100_ide_inw(unsigned long reg) {
+	int status;
+	int timeleft;
+
+	timeleft = IDE_REGISTER_TIMEOUT;
+	/* wait for busy flag */
+	while(timeleft && (*R_ATA_STATUS_DATA & IO_MASK(R_ATA_STATUS_DATA, busy)))
+		timeleft--;
+
+	if(!timeleft) {
+		/*
+		 * If we're asked to read the status register, like for
+		 * example when a command does not complete for an
+		 * extended time, but the ATA interface is stuck in a
+		 * busy state at the *ETRAX* ATA interface level (as has
+		 * happened repeatedly with at least one bad disk), then
+		 * the best thing to do is to pretend that we read
+		 * "busy" in the status register, so the IDE driver will
+		 * time-out, abort the ongoing command and perform a
+		 * reset sequence.  Note that the subsequent OUT_BYTE
+		 * call will also timeout on busy, but as long as the
+		 * write is still performed, everything will be fine.
+		 */
+		if ((reg & IO_MASK (R_ATA_CTRL_DATA, addr))
+		    == IO_FIELD (R_ATA_CTRL_DATA, addr, IDE_STATUS_OFFSET))
+			return BUSY_STAT;
+		else
+			/* For other rare cases we assume 0 is good enough.  */
+			return 0;
+	}
+
+	*R_ATA_CTRL_DATA = reg | IO_STATE(R_ATA_CTRL_DATA, rw, read); /* read data */
+
+	timeleft = IDE_REGISTER_TIMEOUT;
+	/* wait for available */
+	while(timeleft && !((status = *R_ATA_STATUS_DATA) &
+			    IO_MASK(R_ATA_STATUS_DATA, dav)))
+		timeleft--;
+
+	if(!timeleft)
+		return 0;
+
+	LOWDB(printk("inb: 0x%x from reg 0x%x\n", status & 0xff, reg));
+
+        return (unsigned short)status;
+}
+
+unsigned char
+etrax100_ide_inb(unsigned long reg)
+{
+	return (unsigned char)etrax100_ide_inw(reg);
+}
+
+/* PIO timing (in R_ATA_CONFIG)
+ *
+ *                        _____________________________
+ * ADDRESS :     ________/
+ *
+ *                            _______________
+ * DIOR    :     ____________/               \__________
+ *
+ *                               _______________
+ * DATA    :     XXXXXXXXXXXXXXXX_______________XXXXXXXX
+ *
+ *
+ * DIOR is unbuffered while address and data is buffered.
+ * This creates two problems:
+ * 1. The DIOR pulse is to early (because it is unbuffered)
+ * 2. The rise time of DIOR is long
+ *
+ * There are at least three different plausible solutions
+ * 1. Use a pad capable of larger currents in Etrax
+ * 2. Use an external buffer
+ * 3. Make the strobe pulse longer
+ *
+ * Some of the strobe timings below are modified to compensate
+ * for this. This implies a slight performance decrease.
+ *
+ * THIS SHOULD NEVER BE CHANGED!
+ *
+ * TODO: Is this true for the latest LX boards still ?
+ */
+
+#define ATA_DMA2_STROBE  4
+#define ATA_DMA2_HOLD    0
+#define ATA_DMA1_STROBE  4
+#define ATA_DMA1_HOLD    1
+#define ATA_DMA0_STROBE 12
+#define ATA_DMA0_HOLD    9
+#define ATA_PIO4_SETUP   1
+#define ATA_PIO4_STROBE  5
+#define ATA_PIO4_HOLD    0
+#define ATA_PIO3_SETUP   1
+#define ATA_PIO3_STROBE  5
+#define ATA_PIO3_HOLD    1
+#define ATA_PIO2_SETUP   1
+#define ATA_PIO2_STROBE  6
+#define ATA_PIO2_HOLD    2
+#define ATA_PIO1_SETUP   2
+#define ATA_PIO1_STROBE 11
+#define ATA_PIO1_HOLD    4
+#define ATA_PIO0_SETUP   4
+#define ATA_PIO0_STROBE 19
+#define ATA_PIO0_HOLD    4
+
+static int e100_dma_check (ide_drive_t *drive);
+static void e100_dma_start(ide_drive_t *drive);
+static int e100_dma_end (ide_drive_t *drive);
+static void e100_ide_input_data (ide_drive_t *drive, void *, unsigned int);
+static void e100_ide_output_data (ide_drive_t *drive, void *, unsigned int);
+static void e100_atapi_input_bytes(ide_drive_t *drive, void *, unsigned int);
+static void e100_atapi_output_bytes(ide_drive_t *drive, void *, unsigned int);
+static int e100_dma_off (ide_drive_t *drive);
+
+
+/*
+ * 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",
+				 "CONNER CTMA 4000",
+				 "CONNER CTT8000-A",
+				 NULL};
+
+static void tune_e100_ide(ide_drive_t *drive, byte pio)
+{
+	pio = 4;
+	/* pio = ide_get_best_pio_mode(drive, pio, 4, NULL); */
+
+	/* set pio mode! */
+
+	switch(pio) {
+		case 0:
+			*R_ATA_CONFIG = ( IO_FIELD( R_ATA_CONFIG, enable,     1 ) |
+					  IO_FIELD( R_ATA_CONFIG, dma_strobe, ATA_DMA2_STROBE ) |
+					  IO_FIELD( R_ATA_CONFIG, dma_hold,   ATA_DMA2_HOLD ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_setup,  ATA_PIO0_SETUP ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_strobe, ATA_PIO0_STROBE ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_hold,   ATA_PIO0_HOLD ) );
+			break;
+		case 1:
+			*R_ATA_CONFIG = ( IO_FIELD( R_ATA_CONFIG, enable,     1 ) |
+					  IO_FIELD( R_ATA_CONFIG, dma_strobe, ATA_DMA2_STROBE ) |
+					  IO_FIELD( R_ATA_CONFIG, dma_hold,   ATA_DMA2_HOLD ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_setup,  ATA_PIO1_SETUP ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_strobe, ATA_PIO1_STROBE ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_hold,   ATA_PIO1_HOLD ) );
+			break;
+		case 2:
+			*R_ATA_CONFIG = ( IO_FIELD( R_ATA_CONFIG, enable,     1 ) |
+					  IO_FIELD( R_ATA_CONFIG, dma_strobe, ATA_DMA2_STROBE ) |
+					  IO_FIELD( R_ATA_CONFIG, dma_hold,   ATA_DMA2_HOLD ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_setup,  ATA_PIO2_SETUP ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_strobe, ATA_PIO2_STROBE ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_hold,   ATA_PIO2_HOLD ) );
+			break;
+		case 3:
+			*R_ATA_CONFIG = ( IO_FIELD( R_ATA_CONFIG, enable,     1 ) |
+					  IO_FIELD( R_ATA_CONFIG, dma_strobe, ATA_DMA2_STROBE ) |
+					  IO_FIELD( R_ATA_CONFIG, dma_hold,   ATA_DMA2_HOLD ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_setup,  ATA_PIO3_SETUP ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_strobe, ATA_PIO3_STROBE ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_hold,   ATA_PIO3_HOLD ) );
+			break;
+		case 4:
+			*R_ATA_CONFIG = ( IO_FIELD( R_ATA_CONFIG, enable,     1 ) |
+					  IO_FIELD( R_ATA_CONFIG, dma_strobe, ATA_DMA2_STROBE ) |
+					  IO_FIELD( R_ATA_CONFIG, dma_hold,   ATA_DMA2_HOLD ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_setup,  ATA_PIO4_SETUP ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_strobe, ATA_PIO4_STROBE ) |
+					  IO_FIELD( R_ATA_CONFIG, pio_hold,   ATA_PIO4_HOLD ) );
+			break;
+	}
+}
+
+static int e100_dma_setup(ide_drive_t *drive)
+{
+	struct request *rq = drive->hwif->hwgroup->rq;
+
+	if (rq_data_dir(rq)) {
+		e100_read_command = 0;
+
+		RESET_DMA(ATA_TX_DMA_NBR); /* sometimes the DMA channel get stuck so we need to do this */
+		WAIT_DMA(ATA_TX_DMA_NBR);
+	} else {
+		e100_read_command = 1;
+
+		RESET_DMA(ATA_RX_DMA_NBR); /* sometimes the DMA channel get stuck so we need to do this */
+		WAIT_DMA(ATA_RX_DMA_NBR);
+	}
+
+	/* set up the Etrax DMA descriptors */
+	if (e100_ide_build_dmatable(drive)) {
+		ide_map_sg(drive, rq);
+		return 1;
+	}
+
+	return 0;
+}
+
+static void e100_dma_exec_cmd(ide_drive_t *drive, u8 command)
+{
+	/* set the irq handler which will finish the request when DMA is done */
+	ide_set_handler(drive, &etrax_dma_intr, WAIT_CMD, NULL);
+
+	/* issue cmd to drive */
+	etrax100_ide_outb(command, IDE_COMMAND_REG);
+}
+
+void __init
+init_e100_ide (void)
+{
+	volatile unsigned int dummy;
+	int h;
+
+	printk("ide: ETRAX 100LX built-in ATA DMA controller\n");
+
+	/* first fill in some stuff in the ide_hwifs fields */
+
+	for(h = 0; h < MAX_HWIFS; h++) {
+		ide_hwif_t *hwif = &ide_hwifs[h];
+		hwif->mmio = 2;
+		hwif->chipset = ide_etrax100;
+		hwif->tuneproc = &tune_e100_ide;
+                hwif->ata_input_data = &e100_ide_input_data;
+                hwif->ata_output_data = &e100_ide_output_data;
+                hwif->atapi_input_bytes = &e100_atapi_input_bytes;
+                hwif->atapi_output_bytes = &e100_atapi_output_bytes;
+                hwif->ide_dma_check = &e100_dma_check;
+                hwif->ide_dma_end = &e100_dma_end;
+		hwif->dma_setup = &e100_dma_setup;
+		hwif->dma_exec_cmd = &e100_dma_exec_cmd;
+		hwif->dma_start = &e100_dma_start;
+		hwif->OUTB = &etrax100_ide_outb;
+		hwif->OUTW = &etrax100_ide_outw;
+		hwif->OUTBSYNC = &etrax100_ide_outbsync;
+		hwif->INB = &etrax100_ide_inb;
+		hwif->INW = &etrax100_ide_inw;
+		hwif->ide_dma_off_quietly = &e100_dma_off;
+	}
+
+	/* actually reset and configure the etrax100 ide/ata interface */
+
+	*R_ATA_CTRL_DATA = 0;
+	*R_ATA_TRANSFER_CNT = 0;
+	*R_ATA_CONFIG = 0;
+
+	genconfig_shadow = (genconfig_shadow &
+			    ~IO_MASK(R_GEN_CONFIG, dma2) &
+			    ~IO_MASK(R_GEN_CONFIG, dma3) &
+			    ~IO_MASK(R_GEN_CONFIG, ata)) |
+		( IO_STATE( R_GEN_CONFIG, dma3, ata    ) |
+		  IO_STATE( R_GEN_CONFIG, dma2, ata    ) |
+		  IO_STATE( R_GEN_CONFIG, ata,  select ) );
+
+	*R_GEN_CONFIG = genconfig_shadow;
+
+        /* pull the chosen /reset-line low */
+
+#ifdef CONFIG_ETRAX_IDE_G27_RESET
+        REG_SHADOW_SET(R_PORT_G_DATA, port_g_data_shadow, 27, 0);
+#endif
+#ifdef CONFIG_ETRAX_IDE_CSE1_16_RESET
+        REG_SHADOW_SET(port_cse1_addr, port_cse1_shadow, 16, 0);
+#endif
+#ifdef CONFIG_ETRAX_IDE_CSP0_8_RESET
+        REG_SHADOW_SET(port_csp0_addr, port_csp0_shadow, 8, 0);
+#endif
+#ifdef CONFIG_ETRAX_IDE_PB7_RESET
+	port_pb_dir_shadow = port_pb_dir_shadow |
+		IO_STATE(R_PORT_PB_DIR, dir7, output);
+	*R_PORT_PB_DIR = port_pb_dir_shadow;
+	REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, 7, 1);
+#endif
+
+	/* wait some */
+
+	udelay(25);
+
+	/* de-assert bus-reset */
+
+#ifdef CONFIG_ETRAX_IDE_CSE1_16_RESET
+	REG_SHADOW_SET(port_cse1_addr, port_cse1_shadow, 16, 1);
+#endif
+#ifdef CONFIG_ETRAX_IDE_CSP0_8_RESET
+	REG_SHADOW_SET(port_csp0_addr, port_csp0_shadow, 8, 1);
+#endif
+#ifdef CONFIG_ETRAX_IDE_G27_RESET
+	REG_SHADOW_SET(R_PORT_G_DATA, port_g_data_shadow, 27, 1);
+#endif
+
+	/* make a dummy read to set the ata controller in a proper state */
+	dummy = *R_ATA_STATUS_DATA;
+
+	*R_ATA_CONFIG = ( IO_FIELD( R_ATA_CONFIG, enable,     1 ) |
+			  IO_FIELD( R_ATA_CONFIG, dma_strobe, ATA_DMA2_STROBE ) |
+			  IO_FIELD( R_ATA_CONFIG, dma_hold,   ATA_DMA2_HOLD ) |
+			  IO_FIELD( R_ATA_CONFIG, pio_setup,  ATA_PIO4_SETUP ) |
+			  IO_FIELD( R_ATA_CONFIG, pio_strobe, ATA_PIO4_STROBE ) |
+			  IO_FIELD( R_ATA_CONFIG, pio_hold,   ATA_PIO4_HOLD ) );
+
+	*R_ATA_CTRL_DATA = ( IO_STATE( R_ATA_CTRL_DATA, rw,   read) |
+			     IO_FIELD( R_ATA_CTRL_DATA, addr, 1   ) );
+
+	while(*R_ATA_STATUS_DATA & IO_MASK(R_ATA_STATUS_DATA, busy)); /* wait for busy flag*/
+
+	*R_IRQ_MASK0_SET = ( IO_STATE( R_IRQ_MASK0_SET, ata_irq0, set ) |
+			     IO_STATE( R_IRQ_MASK0_SET, ata_irq1, set ) |
+			     IO_STATE( R_IRQ_MASK0_SET, ata_irq2, set ) |
+			     IO_STATE( R_IRQ_MASK0_SET, ata_irq3, set ) );
+
+	printk("ide: waiting %d seconds for drives to regain consciousness\n",
+	       CONFIG_ETRAX_IDE_DELAY);
+
+	h = jiffies + (CONFIG_ETRAX_IDE_DELAY * HZ);
+	while(time_before(jiffies, h)) /* nothing */ ;
+
+	/* reset the dma channels we will use */
+
+	RESET_DMA(ATA_TX_DMA_NBR);
+	RESET_DMA(ATA_RX_DMA_NBR);
+	WAIT_DMA(ATA_TX_DMA_NBR);
+	WAIT_DMA(ATA_RX_DMA_NBR);
+
+}
+
+static int e100_dma_off (ide_drive_t *drive)
+{
+	return 0;
+}
+
+static etrax_dma_descr mydescr;
+
+/*
+ * The following routines are mainly used by the ATAPI drivers.
+ *
+ * These routines will round up any request for an odd number of bytes,
+ * so if an odd bytecount is specified, be sure that there's at least one
+ * extra byte allocated for the buffer.
+ */
+static void
+e100_atapi_input_bytes (ide_drive_t *drive, void *buffer, unsigned int bytecount)
+{
+	unsigned long data_reg = IDE_DATA_REG;
+
+	D(printk("atapi_input_bytes, dreg 0x%x, buffer 0x%x, count %d\n",
+		 data_reg, buffer, bytecount));
+
+	if(bytecount & 1) {
+		printk("warning, odd bytecount in cdrom_in_bytes = %d.\n", bytecount);
+		bytecount++; /* to round off */
+	}
+
+	/* make sure the DMA channel is available */
+	RESET_DMA(ATA_RX_DMA_NBR);
+	WAIT_DMA(ATA_RX_DMA_NBR);
+
+	/* setup DMA descriptor */
+
+	mydescr.sw_len = bytecount;
+	mydescr.ctrl   = d_eol;
+	mydescr.buf    = virt_to_phys(buffer);
+
+	/* start the dma channel */
+
+	*R_DMA_CH3_FIRST = virt_to_phys(&mydescr);
+	*R_DMA_CH3_CMD   = IO_STATE(R_DMA_CH3_CMD, cmd, start);
+
+	/* initiate a multi word dma read using PIO handshaking */
+
+	*R_ATA_TRANSFER_CNT = IO_FIELD(R_ATA_TRANSFER_CNT, count, bytecount >> 1);
+
+	*R_ATA_CTRL_DATA = data_reg |
+		IO_STATE(R_ATA_CTRL_DATA, rw,       read) |
+		IO_STATE(R_ATA_CTRL_DATA, src_dst,  dma) |
+		IO_STATE(R_ATA_CTRL_DATA, handsh,   pio) |
+		IO_STATE(R_ATA_CTRL_DATA, multi,    on) |
+		IO_STATE(R_ATA_CTRL_DATA, dma_size, word);
+
+	/* wait for completion */
+
+	LED_DISK_READ(1);
+	WAIT_DMA(ATA_RX_DMA_NBR);
+	LED_DISK_READ(0);
+
+#if 0
+        /* old polled transfer code
+	 * this should be moved into a new function that can do polled
+	 * transfers if DMA is not available
+	 */
+
+        /* initiate a multi word read */
+
+        *R_ATA_TRANSFER_CNT = wcount << 1;
+
+        *R_ATA_CTRL_DATA = data_reg |
+                IO_STATE(R_ATA_CTRL_DATA, rw,       read) |
+                IO_STATE(R_ATA_CTRL_DATA, src_dst,  register) |
+                IO_STATE(R_ATA_CTRL_DATA, handsh,   pio) |
+                IO_STATE(R_ATA_CTRL_DATA, multi,    on) |
+                IO_STATE(R_ATA_CTRL_DATA, dma_size, word);
+
+        /* svinto has a latency until the busy bit actually is set */
+
+        nop(); nop();
+        nop(); nop();
+        nop(); nop();
+        nop(); nop();
+        nop(); nop();
+
+        /* unit should be busy during multi transfer */
+        while((status = *R_ATA_STATUS_DATA) & IO_MASK(R_ATA_STATUS_DATA, busy)) {
+                while(!(status & IO_MASK(R_ATA_STATUS_DATA, dav)))
+                        status = *R_ATA_STATUS_DATA;
+                *ptr++ = (unsigned short)(status & 0xffff);
+        }
+#endif
+}
+
+static void
+e100_atapi_output_bytes (ide_drive_t *drive, void *buffer, unsigned int bytecount)
+{
+	unsigned long data_reg = IDE_DATA_REG;
+
+	D(printk("atapi_output_bytes, dreg 0x%x, buffer 0x%x, count %d\n",
+		 data_reg, buffer, bytecount));
+
+	if(bytecount & 1) {
+		printk("odd bytecount %d in atapi_out_bytes!\n", bytecount);
+		bytecount++;
+	}
+
+	/* make sure the DMA channel is available */
+	RESET_DMA(ATA_TX_DMA_NBR);
+	WAIT_DMA(ATA_TX_DMA_NBR);
+
+	/* setup DMA descriptor */
+
+	mydescr.sw_len = bytecount;
+	mydescr.ctrl   = d_eol;
+	mydescr.buf    = virt_to_phys(buffer);
+
+	/* start the dma channel */
+
+	*R_DMA_CH2_FIRST = virt_to_phys(&mydescr);
+	*R_DMA_CH2_CMD   = IO_STATE(R_DMA_CH2_CMD, cmd, start);
+
+	/* initiate a multi word dma write using PIO handshaking */
+
+	*R_ATA_TRANSFER_CNT = IO_FIELD(R_ATA_TRANSFER_CNT, count, bytecount >> 1);
+
+	*R_ATA_CTRL_DATA = data_reg |
+		IO_STATE(R_ATA_CTRL_DATA, rw,       write) |
+		IO_STATE(R_ATA_CTRL_DATA, src_dst,  dma) |
+		IO_STATE(R_ATA_CTRL_DATA, handsh,   pio) |
+		IO_STATE(R_ATA_CTRL_DATA, multi,    on) |
+		IO_STATE(R_ATA_CTRL_DATA, dma_size, word);
+
+	/* wait for completion */
+
+	LED_DISK_WRITE(1);
+	WAIT_DMA(ATA_TX_DMA_NBR);
+	LED_DISK_WRITE(0);
+
+#if 0
+        /* old polled write code - see comment in input_bytes */
+
+	/* wait for busy flag */
+        while(*R_ATA_STATUS_DATA & IO_MASK(R_ATA_STATUS_DATA, busy));
+
+        /* initiate a multi word write */
+
+        *R_ATA_TRANSFER_CNT = bytecount >> 1;
+
+        ctrl = data_reg |
+                IO_STATE(R_ATA_CTRL_DATA, rw,       write) |
+                IO_STATE(R_ATA_CTRL_DATA, src_dst,  register) |
+                IO_STATE(R_ATA_CTRL_DATA, handsh,   pio) |
+                IO_STATE(R_ATA_CTRL_DATA, multi,    on) |
+                IO_STATE(R_ATA_CTRL_DATA, dma_size, word);
+
+        LED_DISK_WRITE(1);
+
+        /* Etrax will set busy = 1 until the multi pio transfer has finished
+         * and tr_rdy = 1 after each successful word transfer.
+         * When the last byte has been transferred Etrax will first set tr_tdy = 1
+         * and then busy = 0 (not in the same cycle). If we read busy before it
+         * has been set to 0 we will think that we should transfer more bytes
+         * and then tr_rdy would be 0 forever. This is solved by checking busy
+         * in the inner loop.
+         */
+
+        do {
+                *R_ATA_CTRL_DATA = ctrl | *ptr++;
+                while(!(*R_ATA_STATUS_DATA & IO_MASK(R_ATA_STATUS_DATA, tr_rdy)) &&
+                      (*R_ATA_STATUS_DATA & IO_MASK(R_ATA_STATUS_DATA, busy)));
+        } while(*R_ATA_STATUS_DATA & IO_MASK(R_ATA_STATUS_DATA, busy));
+
+        LED_DISK_WRITE(0);
+#endif
+
+}
+
+/*
+ * This is used for most PIO data transfers *from* the IDE interface
+ */
+static void
+e100_ide_input_data (ide_drive_t *drive, void *buffer, unsigned int wcount)
+{
+	e100_atapi_input_bytes(drive, buffer, wcount << 2);
+}
+
+/*
+ * This is used for most PIO data transfers *to* the IDE interface
+ */
+static void
+e100_ide_output_data (ide_drive_t *drive, void *buffer, unsigned int wcount)
+{
+	e100_atapi_output_bytes(drive, buffer, wcount << 2);
+}
+
+/* we only have one DMA channel on the chip for ATA, so we can keep these statically */
+static etrax_dma_descr ata_descrs[MAX_DMA_DESCRS];
+static unsigned int ata_tot_size;
+
+/*
+ * e100_ide_build_dmatable() prepares a dma request.
+ * Returns 0 if all went okay, returns 1 otherwise.
+ */
+static int e100_ide_build_dmatable (ide_drive_t *drive)
+{
+	ide_hwif_t *hwif = HWIF(drive);
+	struct scatterlist* sg;
+	struct request *rq  = HWGROUP(drive)->rq;
+	unsigned long size, addr;
+	unsigned int count = 0;
+	int i = 0;
+
+	sg = hwif->sg_table;
+
+	ata_tot_size = 0;
+
+	ide_map_sg(drive, rq);
+
+	i = hwif->sg_nents;
+
+	while(i) {
+		/*
+		 * 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.
+		 */
+		/* group sequential buffers into one large buffer */
+		addr = page_to_phys(sg->page) + sg->offset;
+		size = sg_dma_len(sg);
+		while (sg++, --i) {
+			if ((addr + size) != page_to_phys(sg->page) + sg->offset)
+				break;
+			size += sg_dma_len(sg);
+		}
+
+		/* did we run out of descriptors? */
+
+		if(count >= MAX_DMA_DESCRS) {
+			printk("%s: too few DMA descriptors\n", drive->name);
+			return 1;
+		}
+
+		/* however, this case is more difficult - R_ATA_TRANSFER_CNT cannot be more
+		   than 65536 words per transfer, so in that case we need to either
+		   1) use a DMA interrupt to re-trigger R_ATA_TRANSFER_CNT and continue with
+		      the descriptors, or
+		   2) simply do the request here, and get dma_intr to only ide_end_request on
+		      those blocks that were actually set-up for transfer.
+		*/
+
+		if(ata_tot_size + size > 131072) {
+			printk("too large total ATA DMA request, %d + %d!\n", ata_tot_size, (int)size);
+			return 1;
+		}
+
+		/* If size > 65536 it has to be splitted into new descriptors. Since we don't handle
+                   size > 131072 only one split is necessary */
+
+		if(size > 65536) {
+ 		        /* ok we want to do IO at addr, size bytes. set up a new descriptor entry */
+                        ata_descrs[count].sw_len = 0;  /* 0 means 65536, this is a 16-bit field */
+                        ata_descrs[count].ctrl = 0;
+                        ata_descrs[count].buf = addr;
+                        ata_descrs[count].next = virt_to_phys(&ata_descrs[count + 1]);
+                        count++;
+                        ata_tot_size += 65536;
+                        /* size and addr should refere to not handled data */
+                        size -= 65536;
+                        addr += 65536;
+                }
+		/* ok we want to do IO at addr, size bytes. set up a new descriptor entry */
+                if(size == 65536) {
+			ata_descrs[count].sw_len = 0;  /* 0 means 65536, this is a 16-bit field */
+                } else {
+			ata_descrs[count].sw_len = size;
+                }
+		ata_descrs[count].ctrl = 0;
+		ata_descrs[count].buf = addr;
+		ata_descrs[count].next = virt_to_phys(&ata_descrs[count + 1]);
+		count++;
+		ata_tot_size += size;
+	}
+
+	if (count) {
+		/* set the end-of-list flag on the last descriptor */
+		ata_descrs[count - 1].ctrl |= d_eol;
+		/* return and say all is ok */
+		return 0;
+	}
+
+	printk("%s: empty DMA table?\n", drive->name);
+	return 1;	/* let the PIO routines handle this weirdness */
+}
+
+static int config_drive_for_dma (ide_drive_t *drive)
+{
+        const char **list;
+        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 */
+}
+
+/*
+ * etrax_dma_intr() is the handler for disk read/write DMA interrupts
+ */
+static ide_startstop_t etrax_dma_intr (ide_drive_t *drive)
+{
+	LED_DISK_READ(0);
+	LED_DISK_WRITE(0);
+
+	return ide_dma_intr(drive);
+}
+
+/*
+ * Functions below 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 e100_dma_check(ide_drive_t *drive)
+{
+	return config_drive_for_dma (drive);
+}
+
+static int e100_dma_end(ide_drive_t *drive)
+{
+	/* TODO: check if something went wrong with the DMA */
+	return 0;
+}
+
+static void e100_dma_start(ide_drive_t *drive)
+{
+	if (e100_read_command) {
+		/* begin DMA */
+
+		/* need to do this before RX DMA due to a chip bug
+		 * it is enough to just flush the part of the cache that
+		 * corresponds to the buffers we start, but since HD transfers
+		 * usually are more than 8 kB, it is easier to optimize for the
+		 * normal case and just flush the entire cache. its the only
+		 * way to be sure! (OB movie quote)
+		 */
+		flush_etrax_cache();
+		*R_DMA_CH3_FIRST = virt_to_phys(ata_descrs);
+		*R_DMA_CH3_CMD   = IO_STATE(R_DMA_CH3_CMD, cmd, start);
+
+		/* initiate a multi word dma read using DMA handshaking */
+
+		*R_ATA_TRANSFER_CNT =
+			IO_FIELD(R_ATA_TRANSFER_CNT, count, ata_tot_size >> 1);
+
+		*R_ATA_CTRL_DATA =
+			IO_FIELD(R_ATA_CTRL_DATA, data, IDE_DATA_REG) |
+			IO_STATE(R_ATA_CTRL_DATA, rw,       read) |
+			IO_STATE(R_ATA_CTRL_DATA, src_dst,  dma)  |
+			IO_STATE(R_ATA_CTRL_DATA, handsh,   dma)  |
+			IO_STATE(R_ATA_CTRL_DATA, multi,    on)   |
+			IO_STATE(R_ATA_CTRL_DATA, dma_size, word);
+
+		LED_DISK_READ(1);
+
+		D(printk("dma read of %d bytes.\n", ata_tot_size));
+
+	} else {
+		/* writing */
+		/* begin DMA */
+
+		*R_DMA_CH2_FIRST = virt_to_phys(ata_descrs);
+		*R_DMA_CH2_CMD   = IO_STATE(R_DMA_CH2_CMD, cmd, start);
+
+		/* initiate a multi word dma write using DMA handshaking */
+
+		*R_ATA_TRANSFER_CNT =
+			IO_FIELD(R_ATA_TRANSFER_CNT, count, ata_tot_size >> 1);
+
+		*R_ATA_CTRL_DATA =
+			IO_FIELD(R_ATA_CTRL_DATA, data,     IDE_DATA_REG) |
+			IO_STATE(R_ATA_CTRL_DATA, rw,       write) |
+			IO_STATE(R_ATA_CTRL_DATA, src_dst,  dma) |
+			IO_STATE(R_ATA_CTRL_DATA, handsh,   dma) |
+			IO_STATE(R_ATA_CTRL_DATA, multi,    on) |
+			IO_STATE(R_ATA_CTRL_DATA, dma_size, word);
+
+		LED_DISK_WRITE(1);
+
+		D(printk("dma write of %d bytes.\n", ata_tot_size));
+	}
+}