Message-Id: <1200088609.6213.3.camel@localhost.localdomain>
Date:	Fri, 11 Jan 2008 21:56:49 +0000
From:	Adrian McMenamin <adrian@...golddream.dyndns.info>
To:	Jens Axboe <jens.axboe@...cle.com>
Cc:	Paul Mundt <lethal@...ux-sh.org>,
	linux-sh <linux-sh@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] SH/Dreamcast - add support for GD-Rom CDROM drive on
	SEGA Dreamcast


On Thu, 2008-01-10 at 23:25 +0000, Adrian McMenamin wrote:
> From: Adrian McMenamin <adrian@...en.demon.co.uk>
> 
> This patch adds support for the GD-Rom drive, SEGA's proprietary implementation of an IDE CD Rom for the SEGA Dreamcast. This driver implements Sega's Packet Interface (SPI) - at least partially. It will also read disks in SEGA's propreitary GD format.
> 
> Unlike previous drivers (which were never in mainline) this uses DMA and not PIO to read disks. It is a new driver, not a refactoring of old drivers. 
> 
> Signed-off by: Adrian McMenamin <adrian@...en.demon.co.uk>
> 
> (Jens - this awaits your ack before going in Paul's queue for the 2.6.25 window)
> 
> --------
> 
> 

Unfortunately, there was one small mistake (a repeated assignment), in
the patch posted yesterday. Here is a corrected version.

Signed-off by: Adrian McMenamin <adrian@...en.demon.co.uk>


diff -rupN a/drivers/block/Kconfig b/drivers/block/Kconfig
--- a/drivers/block/Kconfig	2008-01-11 21:33:18.000000000 +0000
+++ b/drivers/block/Kconfig	2008-01-11 20:55:40.000000000 +0000
@@ -105,6 +105,17 @@ config PARIDE
 	  "MicroSolutions backpack protocol", "DataStor Commuter protocol"
 	  etc.).
 
+config GDROM
+	tristate "SEGA Dreamcast GD-ROM drive"
+	depends on SH_DREAMCAST
+	help
+	  A standard SEGA Dreamcast comes with a modified CD ROM drive called a
+	  "GD-ROM" by SEGA to signify it is capable of reading special disks
+	  with up to 1 GB of data. This drive will also read standard CD ROM
+	  disks. Select this option to access any disks in your GD ROM drive.
+	  Most users will want to say "Y" here.
+	  You can also build this as a module which will be called gdrom.ko
+
 source "drivers/block/paride/Kconfig"
 
 config BLK_CPQ_DA
diff -rupN a/drivers/cdrom/gdrom.c b/drivers/cdrom/gdrom.c
--- a/drivers/cdrom/gdrom.c	1970-01-01 01:00:00.000000000 +0100
+++ b/drivers/cdrom/gdrom.c	2008-01-11 20:55:40.000000000 +0000
@@ -0,0 +1,785 @@
+/* GD ROM driver for the SEGA Dreamcast
+ * copyright Adrian McMenamin, 2007
+ * With thanks to Marcus Comstedt and Nathan Keynes
+ * for work in reversing PIO and DMA
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/dma-mapping.h>
+#include <linux/cdrom.h>
+#include <linux/genhd.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/interrupt.h>
+#include <linux/device.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
+#include <linux/platform_device.h>
+#include <scsi/scsi.h>
+#include <asm/io.h>
+#include <asm/dma.h>
+#include <asm/delay.h>
+#include <asm/mach/dma.h>
+#include <asm/mach/sysasic.h>
+
+#define GDROM_DEV_NAME "gdrom"
+#define GD_SESSION_OFFSET 150
+
+/* GD Rom commands */
+#define GDROM_COM_SOFTRESET 0x08
+#define GDROM_COM_EXECDIAG 0x90
+#define GDROM_COM_PACKET 0xA0
+#define GDROM_COM_IDDEV 0xA1
+
+/* GD Rom registers */
+#define GDROM_BASE_REG 			0xA05F7000
+#define GDROM_ALTSTATUS_REG 		(GDROM_BASE_REG + 0x18)
+#define GDROM_DATA_REG 			(GDROM_BASE_REG + 0x80)
+#define GDROM_ERROR_REG 		(GDROM_BASE_REG + 0x84)
+#define GDROM_INTSEC_REG 		(GDROM_BASE_REG + 0x88)
+#define GDROM_SECNUM_REG 		(GDROM_BASE_REG + 0x8C)
+#define GDROM_BCL_REG  			(GDROM_BASE_REG + 0x90)
+#define GDROM_BCH_REG 			(GDROM_BASE_REG + 0x94)
+#define GDROM_DSEL_REG 			(GDROM_BASE_REG + 0x98)
+#define GDROM_STATUSCOMMAND_REG 	(GDROM_BASE_REG + 0x9C)
+#define GDROM_RESET_REG 		(GDROM_BASE_REG + 0x4E4)
+
+#define GDROM_DMA_STARTADDR_REG 	(GDROM_BASE_REG + 0x404)
+#define GDROM_DMA_LENGTH_REG 		(GDROM_BASE_REG + 0x408)
+#define GDROM_DMA_DIRECTION_REG 	(GDROM_BASE_REG + 0x40C)
+#define GDROM_DMA_ENABLE_REG 		(GDROM_BASE_REG + 0x414)
+#define GDROM_DMA_STATUS_REG 		(GDROM_BASE_REG + 0x418)
+#define GDROM_DMA_WAIT_REG 		(GDROM_BASE_REG + 0x4A0)
+#define GDROM_DMA_ACCESS_CTRL_REG 	(GDROM_BASE_REG + 0x4B8)
+
+#define GDROM_HARD_SECTOR 	2048
+#define BLOCK_LAYER_SECTOR 	512
+#define GD_TO_BLK 		4
+
+static const struct {
+	int sense_key;
+	const char * const text;
+} sense_texts[] = {
+	{NO_SENSE, "OK"},
+	{RECOVERED_ERROR, "Recovered from error"},
+	{NOT_READY, "Device not ready"},
+	{MEDIUM_ERROR, "Disk not ready"},
+	{HARDWARE_ERROR, "Hardware error"},
+	{ILLEGAL_REQUEST, "Command has failed"},
+	{UNIT_ATTENTION, "Device needs attention - disk may have been changed"},
+	{DATA_PROTECT, "Data protection error"},
+	{ABORTED_COMMAND, "Command aborted"},
+};
+
+static struct platform_device *pd;
+static int gdrom_major;
+static wait_queue_head_t command_queue;
+static wait_queue_head_t request_queue;
+
+static DEFINE_SPINLOCK(gdrom_lock);
+static void gdrom_readdisk_dma(struct work_struct *work);
+static DECLARE_WORK(work, gdrom_readdisk_dma);
+static LIST_HEAD(gdrom_deferred);
+
+struct gdromtoc {
+	unsigned int entry[99];
+	unsigned int first, last;
+	unsigned int leadout;
+};
+
+static struct gdrom_unit {
+	struct gendisk *disk;
+	struct cdrom_device_info *cd_info;
+	int status;
+	int pending;
+	int transfer;
+	char disk_type;
+	struct gdromtoc *toc;
+	struct request_queue *gdrom_rq;
+} gd;
+
+struct gdrom_id {
+	char mid;
+	char modid;
+	char verid;
+	char padA[13];
+	char mname[16];
+	char modname[16];
+	char firmver[16];
+	char padB[16];
+};
+
+static int gdrom_getsense(short *bufstring);
+static int gdrom_packetcommand(struct cdrom_device_info *cd_info, struct packet_command *command);
+static int gdrom_hardreset(struct cdrom_device_info *cd_info);
+
+static bool gdrom_is_busy(void)
+{
+	return (ctrl_inb(GDROM_ALTSTATUS_REG) & 0x80) != 0;
+}
+
+static bool gdrom_data_request(void)
+{
+ 	return (ctrl_inb(GDROM_ALTSTATUS_REG) & 0x88) == 8;
+}
+
+static void gdrom_wait_clrbusy(void)
+{
+	/* long timeouts - typical for a CD Rom */
+	unsigned long timeout = jiffies + HZ * 60;
+	while ((ctrl_inb(GDROM_ALTSTATUS_REG) & 0x80) && (time_before(jiffies, timeout)))
+		cpu_relax();
+}
+
+static void gdrom_wait_busy_sleeps(void)
+{
+	unsigned long timeout;
+	/* Wait to get busy first */
+	timeout = jiffies + HZ * 60;
+	while (!gdrom_is_busy() && time_before(jiffies, timeout))
+		cpu_relax();
+	/* Now wait for busy to clear */
+	gdrom_wait_clrbusy();
+}
+
+static void gdrom_identifydevice(void *buf)
+{
+	int c;
+	short *data = buf;
+	gdrom_wait_clrbusy();
+	ctrl_outb(GDROM_COM_IDDEV, GDROM_STATUSCOMMAND_REG);
+	gdrom_wait_busy_sleeps();
+	/* now read in the data */
+	for (c = 0; c < 40; c++)
+		data[c] = ctrl_inw(GDROM_DATA_REG);
+}
+
+static void gdrom_spicommand(void *spi_string, int buflen)
+{
+	short *cmd = spi_string;
+	/* ensure IRQ_WAIT is set */
+	ctrl_outb(0x08, GDROM_ALTSTATUS_REG);
+	/* specify how many bytes we expect back */
+	ctrl_outb(buflen & 0xFF, GDROM_BCL_REG);
+	ctrl_outb((buflen >> 8) & 0xFF, GDROM_BCH_REG);
+	/* other parameters */
+	ctrl_outb(0, GDROM_INTSEC_REG);
+	ctrl_outb(0, GDROM_SECNUM_REG);
+	ctrl_outb(0, GDROM_ERROR_REG);
+	/* Wait until we can go */
+	gdrom_wait_clrbusy();
+	ctrl_outb(GDROM_COM_PACKET, GDROM_STATUSCOMMAND_REG);
+	while (!gdrom_data_request())
+		cpu_relax();
+	outsw(PHYSADDR(GDROM_DATA_REG), cmd, 6);
+}
+
+/* gdrom_command_executediagnostic:
+ * Used to probe for presence of working GDROM
+ * Restarts GDROM device and then applies standard ATA 3
+ * Execute Diagnostic Command: a return of '1' indicates device 0
+ * present and device 1 absent
+ */
+static char gdrom_execute_diagnostic(void)
+{
+	gdrom_hardreset(gd.cd_info);
+	gdrom_wait_clrbusy();
+	ctrl_outb(GDROM_COM_EXECDIAG, GDROM_STATUSCOMMAND_REG);
+	gdrom_wait_busy_sleeps();
+	return ctrl_inb(GDROM_ERROR_REG);
+}
+
+/*
+ * Prepare disk command
+ * byte 0 = 0x70
+ * byte 1 = 0x1f
+ */
+static int gdrom_preparedisk_cmd(void)
+{
+	struct packet_command *spin_command;
+	spin_command = kzalloc(sizeof(struct packet_command), GFP_KERNEL);
+	if (!spin_command)
+		return -ENOMEM;
+	spin_command->cmd[0] = 0x70;
+	spin_command->cmd[2] = 0x1f;
+	spin_command->buflen = 0;
+	gd.pending = 1;
+	gdrom_packetcommand(gd.cd_info, spin_command);
+	/* 60 second timeout */
+	wait_event_interruptible_timeout(command_queue, gd.pending == 0, HZ * 60);
+	gd.pending = 0;
+	kfree(spin_command);
+	if (gd.status & 0x01) {
+		/* log an error */
+		gdrom_getsense(NULL);
+		return -EIO;
+	}
+	return 0;
+}
+
+/*
+ * Read TOC command
+ * byte 0 = 0x14
+ * byte 1 = session
+ * byte 3 = sizeof TOC >> 8  ie upper byte
+ * byte 4 = sizeof TOC & 0xff ie lower byte
+ */
+static int gdrom_readtoc_cmd(struct gdromtoc *toc, int session)
+{
+	int tocsize;
+	struct packet_command *toc_command;
+	toc_command = kzalloc(sizeof(struct packet_command), GFP_KERNEL);
+	if (!toc_command)
+		return -ENOMEM;
+	tocsize = sizeof(struct gdromtoc);
+	toc_command->cmd[0] = 0x14;
+	toc_command->cmd[1] = session;
+	toc_command->cmd[3] = tocsize >> 8;
+	toc_command->cmd[4] = tocsize & 0xff;
+	toc_command->buflen = tocsize;
+	gd.pending = 1;
+	gdrom_packetcommand(gd.cd_info, toc_command);
+	wait_event_interruptible_timeout(command_queue, gd.pending == 0, HZ * 60);
+	gd.pending = 0;
+	insw(PHYSADDR(GDROM_DATA_REG), toc, tocsize/2);
+	kfree(toc_command);
+	if (gd.status & 0x01)
+		return -EINVAL;
+	return 0;
+}
+
+/* TOC helpers */
+static int get_entry_lba(int track)
+{
+	return (cpu_to_be32(track & 0xffffff00) - GD_SESSION_OFFSET);
+}
+
+static int get_entry_q_ctrl(int track)
+{
+	return (track & 0x000000f0) >> 4;
+}
+
+static int get_entry_track(int track)
+{
+	return (track & 0x0000ff00) >> 8;
+}
+
+static int gdrom_get_last_session(struct cdrom_device_info *cd_info, struct cdrom_multisession *ms_info)
+{
+	int fentry, lentry, track, data, tocuse, err;
+	if (!gd.toc)
+		return -ENOMEM;
+	tocuse = 1;
+	/* Check if GD-ROM */
+	err = gdrom_readtoc_cmd(gd.toc, 1);
+	/* Not a GD-ROM so check if standard CD-ROM */
+	if (err) {
+		tocuse = 0;
+		err = gdrom_readtoc_cmd(gd.toc, 0);
+		if (err) {
+			printk(KERN_INFO "GDROM: Could not get CD table of contents\n");
+			return -ENXIO;
+		}
+	}
+
+	fentry = get_entry_track(gd.toc->first);
+	lentry = get_entry_track(gd.toc->last);
+	/* Find the first data track */
+	track = get_entry_track(gd.toc->last);
+	do {
+		data = gd.toc->entry[track - 1];
+		if (get_entry_q_ctrl(data))
+			break;	/* ie a real data track */
+		track--;
+	} while (track >= fentry);
+
+	if ((track > 100) || (track < get_entry_track(gd.toc->first))) {
+		gdrom_getsense(NULL);
+		printk(KERN_INFO "GDROM: No data on the last session of the CD\n");
+		return -ENXIO;
+	}
+
+	ms_info->addr_format = CDROM_LBA;
+	ms_info->addr.lba = get_entry_lba(data);
+	ms_info->xa_flag = 1;
+	return 0;
+}
+
+static int gdrom_open(struct cdrom_device_info *cd_info, int purpose)
+{
+	/* spin up the disk */
+	return gdrom_preparedisk_cmd();
+}
+
+/* this function is required even if empty */
+static void gdrom_release(struct cdrom_device_info *cd_info)
+{
+}
+
+static int gdrom_drivestatus(struct cdrom_device_info *cd_info, int ignore)
+{
+	/* read the sense key */
+	char sense = ctrl_inb(GDROM_ERROR_REG);
+	sense &= 0xF0;
+	if (sense == 0)
+		return CDS_DISC_OK;
+	if (sense == 0x20)
+		return CDS_DRIVE_NOT_READY;
+	/* default */
+	return CDS_NO_INFO;
+}
+
+static int gdrom_mediachanged(struct cdrom_device_info *cd_info, int ignore)
+{
+	/* check the sense key */
+	return (ctrl_inb(GDROM_ERROR_REG) & 0xF0) == 0x60;
+}
+
+/* reset the G1 bus */
+static int gdrom_hardreset(struct cdrom_device_info *cd_info)
+{
+	int count;
+	ctrl_outl(0x1fffff, GDROM_RESET_REG);
+	for (count = 0xa0000000; count < 0xa0200000; count += 4)
+		ctrl_inl(count);
+	return 0;
+}
+
+/* keep the function looking like the universal CD Rom specification - returning int*/
+static int gdrom_packetcommand(struct cdrom_device_info *cd_info, struct packet_command *command)
+{
+	gdrom_spicommand(&command->cmd, command->buflen);
+	return 0;
+}
+
+/* Get Sense SPI command
+ * From Marcus Comstedt
+ * cmd = 0x13
+ * cmd + 4 = length of returned buffer
+ * Returns 5 16 bit words
+ */
+static int gdrom_getsense(short *bufstring)
+{
+	struct packet_command *sense_command;
+	short sense[5];
+	int sense_key;
+	if (gd.pending)
+		return -EIO;
+
+	/* allocate command and buffer */
+	sense_command = kzalloc(sizeof(struct packet_command), GFP_KERNEL);
+	if (!sense_command)
+		return -ENOMEM;
+
+	sense_command->cmd[0] = 0x13;
+	sense_command->cmd[4] = 10;
+	sense_command->buflen = 10;
+
+	gd.pending = 1;
+	gdrom_packetcommand(gd.cd_info, sense_command);
+	/* 60 second timeout */
+	wait_event_interruptible_timeout(command_queue, gd.pending == 0, HZ * 60);
+	gd.pending = 0;
+	kfree(sense_command);
+	insw(PHYSADDR(GDROM_DATA_REG), &sense, 5);
+	if (sense[1] & 40) {
+		printk(KERN_INFO "GDROM: Drive not ready - command aborted\n");
+		return -EIO;
+	}
+	sense_key = sense[1] & 0x0F;
+	if (sense_key < ARRAY_SIZE(sense_texts))
+ 		printk(KERN_INFO "GDROM: %s\n", sense_texts[sense_key].text);
+ 	else
+ 		printk(KERN_ERR "GDROM: Unknown sense key: %d\n", sense_key);
+  
+ 	if (bufstring)			/* return additional sense data */
+		memcpy(bufstring, &sense[4], 2); /* return additional sense data */
+
+	if (sense_key < 2)
+		return 0;
+	return -EIO;
+}
+
+static struct cdrom_device_ops gdrom_ops = {
+	.open			= gdrom_open,
+	.release		= gdrom_release,
+	.drive_status		= gdrom_drivestatus,
+	.media_changed		= gdrom_mediachanged,
+	.get_last_session	= gdrom_get_last_session,
+	.reset			= gdrom_hardreset,
+	.capability		= CDC_MULTI_SESSION | CDC_MEDIA_CHANGED |
+				  CDC_RESET | CDC_DRIVE_STATUS | CDC_CD_R,
+	.n_minors		= 1,
+};
+
+static int gdrom_bdops_open(struct inode *inode, struct file *file)
+{
+	return cdrom_open(gd.cd_info, inode, file);
+}
+
+static int gdrom_bdops_release(struct inode *inode, struct file *file)
+{
+	return cdrom_release(gd.cd_info, file);
+}
+
+static int gdrom_bdops_mediachanged(struct gendisk *disk)
+{
+	return cdrom_media_changed(gd.cd_info);
+}
+
+static int gdrom_bdops_ioctl(struct inode *inode, struct file *file, unsigned cmd, unsigned long arg)
+{
+	return cdrom_ioctl(file, gd.cd_info, inode, cmd, arg);
+}
+
+static struct block_device_operations gdrom_bdops = {
+	.owner			= THIS_MODULE,
+	.open			= gdrom_bdops_open,
+	.release		= gdrom_bdops_release,
+	.media_changed		= gdrom_bdops_mediachanged,
+	.ioctl			= gdrom_bdops_ioctl,
+};
+
+static irqreturn_t gdrom_command_interrupt(int irq, void *dev_id)
+{
+	gd.status = ctrl_inb(GDROM_STATUSCOMMAND_REG);
+	if (gd.pending != 1)
+		return IRQ_HANDLED;
+	gd.pending = 0;
+	wake_up_interruptible(&command_queue);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t gdrom_dma_interrupt(int irq, void *dev_id)
+{
+	gd.status = ctrl_inb(GDROM_STATUSCOMMAND_REG);
+	if (gd.transfer != 1)
+		return IRQ_HANDLED;
+	gd.transfer = 0;
+	wake_up_interruptible(&request_queue);
+	return IRQ_HANDLED;
+}
+
+static int __devinit gdrom_set_interrupt_handlers(void)
+{
+	int err;
+	init_waitqueue_head(&command_queue);
+	err = request_irq(HW_EVENT_GDROM_CMD, gdrom_command_interrupt, IRQF_DISABLED, "gdrom_command", &gd);
+	if (err)
+		return err;
+	init_waitqueue_head(&request_queue);
+	err = request_irq(HW_EVENT_GDROM_DMA, gdrom_dma_interrupt, IRQF_DISABLED, "gdrom_dma", &gd);
+	if (err)
+		free_irq(HW_EVENT_GDROM_CMD, &gd);
+	return err;
+}
+
+/* Implement DMA read using SPI command
+ * 0 -> 0x30
+ * 1 -> mode
+ * 2 -> block >> 16
+ * 3 -> block >> 8
+ * 4 -> block
+ * 8 -> sectors >> 16
+ * 9 -> sectors >> 8
+ * 10 -> sectors
+ */
+static void gdrom_readdisk_dma(struct work_struct *work)
+{
+	int err, block, block_cnt;
+	struct packet_command *read_command;
+	struct list_head *elem, *next;
+	struct request *req;
+	unsigned long timeout;
+	if (list_empty(&gdrom_deferred))
+		return;
+	read_command = kzalloc(sizeof(struct packet_command), GFP_KERNEL);
+	if (!read_command)
+		return; /* get more memory later? */
+	read_command->cmd[0] = 0x30;
+	read_command->cmd[1] = 0x20;
+	spin_lock(&gdrom_lock);
+	list_for_each_safe(elem, next, &gdrom_deferred) {
+		req = list_entry(elem, struct request, queuelist);
+		spin_unlock(&gdrom_lock);
+		block = req->sector/GD_TO_BLK + GD_SESSION_OFFSET;
+		block_cnt = req->nr_sectors/GD_TO_BLK;
+		ctrl_outl(PHYSADDR(req->buffer), GDROM_DMA_STARTADDR_REG);
+		ctrl_outl(block_cnt * GDROM_HARD_SECTOR, GDROM_DMA_LENGTH_REG);
+		ctrl_outl(1, GDROM_DMA_DIRECTION_REG);
+		ctrl_outl(1, GDROM_DMA_ENABLE_REG);
+		read_command->cmd[2] = (block >> 16) & 0xFF;
+		read_command->cmd[3] = (block >> 8) & 0xFF;
+		read_command->cmd[4] = block & 0xFF;
+		read_command->cmd[8] = (block_cnt >> 16) & 0xFF;
+		read_command->cmd[9] = (block_cnt >> 8) & 0xFF;
+		read_command->cmd[10] = block_cnt & 0xFF;
+		/* set for DMA */
+		ctrl_outb(1, GDROM_ERROR_REG);
+		/* other registers */
+		ctrl_outb(0, GDROM_SECNUM_REG);
+		ctrl_outb(0, GDROM_BCL_REG);
+		ctrl_outb(0, GDROM_BCH_REG);
+		ctrl_outb(0, GDROM_DSEL_REG);
+		ctrl_outb(0, GDROM_INTSEC_REG);
+		/* In multiple DMA transfers need to wait */
+		timeout = jiffies + HZ / 2;
+		while (gdrom_is_busy() && time_before(jiffies, timeout))
+			cpu_relax();
+		ctrl_outb(GDROM_COM_PACKET, GDROM_STATUSCOMMAND_REG);
+		timeout = jiffies + HZ / 2;
+		while (gdrom_is_busy() && time_before(jiffies, timeout))
+			cpu_relax();
+		gd.pending = 1;
+		gd.transfer = 1;
+		outsw(PHYSADDR(GDROM_DATA_REG), &read_command->cmd, 6);
+		timeout = jiffies + HZ / 2;
+		while (ctrl_inb(GDROM_DMA_STATUS_REG) &&
+ 		       time_before(jiffies, timeout))
+			cpu_relax();
+		ctrl_outb(1, GDROM_DMA_STATUS_REG);
+		/* 5 second error margin here seems more reasonable */
+		wait_event_interruptible_timeout(request_queue, gd.transfer == 0, HZ * 5);
+		err = gd.transfer;
+		gd.transfer = 0;
+		gd.pending = 0;
+		/* now seek to take the request spinlock
+ 		 * before handling ending the request */
+		spin_lock(&gdrom_lock);
+		list_del_init(&req->queuelist);
+		end_dequeued_request(req, 1 - err);
+	}
+	spin_unlock(&gdrom_lock);
+	kfree(read_command);
+}
+
+static void gdrom_request_handler_dma(struct request *req)
+{
+	/* dequeue, add to list of deferred work
+ 	 * and then schedule workqueue */
+	blkdev_dequeue_request(req);
+	list_add_tail(&req->queuelist, &gdrom_deferred);
+	schedule_work(&work);
+}
+
+static void gdrom_request(struct request_queue *rq)
+{
+	struct request *req;
+	while ((req = elv_next_request(rq)) != NULL) {
+		if (!blk_fs_request(req)) {
+			printk(KERN_DEBUG "GDROM: Non-fs request ignored\n");
+			end_request(req, 0);
+		}
+		if (rq_data_dir(req) != READ) {
+			printk(KERN_NOTICE "GDROM: Read only device - write request ignored\n");
+			end_request(req, 0);
+		}
+		if (req->nr_sectors)
+			gdrom_request_handler_dma(req);
+		else
+			end_request(req, 0);
+	}
+}
+
+/* Print string identifying GD ROM device */
+static int __devinit gdrom_outputversion(void)
+{
+	struct gdrom_id *id;
+	char *model_name, *manuf_name, *firmw_ver;
+	int err = -ENOMEM;
+	/* query device ID */
+	id = kzalloc(sizeof(struct gdrom_id), GFP_KERNEL);
+	if (!id)
+		return err;
+	gdrom_identifydevice(id);
+	model_name = kstrndup(id->modname, 16, GFP_KERNEL);
+	if (!model_name)
+		goto free_id;
+	manuf_name = kstrndup(id->mname, 16, GFP_KERNEL);
+	if (!manuf_name)
+		goto free_model_name;
+	firmw_ver = kstrndup(id->firmver, 16, GFP_KERNEL);
+	if (!firmw_ver)
+		goto free_manuf_name;
+	printk(KERN_INFO "GDROM: %s from %s with firmware %s\n", model_name, manuf_name, firmw_ver);
+	err = 0;
+	kfree(firmw_ver);
+free_manuf_name:
+	kfree(manuf_name);
+free_model_name:
+	kfree(model_name);
+free_id:
+	kfree(id);
+	return err;
+}
+
+/* set the default mode for DMA transfer */
+static void __devinit gdrom_init_dma_mode(void)
+{
+	ctrl_outb(0x13, GDROM_ERROR_REG);
+	ctrl_outb(0x22, GDROM_INTSEC_REG);
+	gdrom_wait_clrbusy();
+	ctrl_outb(0xEF, GDROM_STATUSCOMMAND_REG);
+	gdrom_wait_busy_sleeps();
+	ctrl_outl(0x8843407F, GDROM_DMA_ACCESS_CTRL_REG); /* memory setting */
+	ctrl_outl(9, GDROM_DMA_WAIT_REG); /* DMA word setting */
+}
+
+static void __devinit probe_gdrom_setupcd(void)
+{
+	gd.cd_info->ops = &gdrom_ops;
+	gd.cd_info->capacity = 1;
+	strcpy(gd.cd_info->name, GDROM_DEV_NAME);
+	gd.cd_info->mask = CDC_CLOSE_TRAY|CDC_OPEN_TRAY|CDC_LOCK|CDC_SELECT_DISC;
+}
+
+static void __devinit probe_gdrom_setupdisk(void)
+{
+	gd.disk->major = gdrom_major;
+	gd.disk->first_minor = 1;
+	gd.disk->minors = 1;
+	strcpy(gd.disk->disk_name, GDROM_DEV_NAME);
+}
+
+static void __devinit probe_gdrom_setupqueue(void)
+{
+	blk_queue_hardsect_size(gd.gdrom_rq, GDROM_HARD_SECTOR);
+	/* using DMA so memory will need to be contiguous */
+	blk_queue_max_hw_segments(gd.gdrom_rq, 1);
+	/* set a large max size to get most from DMA */
+	blk_queue_max_segment_size(gd.gdrom_rq, 0x40000);
+	gd.disk->queue = gd.gdrom_rq;
+	gdrom_init_dma_mode();
+}
+
+/*
+ * register this as a block device and as compliant with the
+ * universal CD Rom driver interface
+ */
+static int __devinit probe_gdrom(struct platform_device *devptr)
+{
+	int err;
+	if (gdrom_execute_diagnostic() != 1) {
+		printk(KERN_WARNING "GDROM: ATA Probe for GDROM failed.\n");
+		return -ENODEV;
+	}
+	if (gdrom_outputversion())
+		return -ENOMEM;
+	gdrom_major = register_blkdev(0, GDROM_DEV_NAME);
+	if (gdrom_major <= 0)
+		return gdrom_major;
+	printk(KERN_INFO "GDROM: Block device is registered with major number %d\n", gdrom_major);
+	gd.cd_info = kzalloc(sizeof(struct cdrom_device_info), GFP_KERNEL);
+	if (!gd.cd_info) {
+		err = -ENOMEM;
+		goto probe_fail_no_mem;
+	}
+	probe_gdrom_setupcd();
+	gd.disk = alloc_disk(1);
+	if (!gd.disk) {
+		err = -ENODEV;
+		goto probe_fail_no_disk;
+	}
+	probe_gdrom_setupdisk();
+	if (register_cdrom(gd.cd_info)) {
+		err = -ENODEV;
+		goto probe_fail_cdrom_register;
+	}
+	gd.disk->fops = &gdrom_bdops;
+	/* latch on to the interrupt */
+	err = gdrom_set_interrupt_handlers();
+	if (err)
+		goto probe_fail_cmdirq_register;
+	gd.gdrom_rq = blk_init_queue(gdrom_request, &gdrom_lock);
+	if (!gd.gdrom_rq)
+		goto probe_fail_requestq;
+	probe_gdrom_setupqueue();
+	gd.toc = kzalloc(sizeof(struct gdromtoc), GFP_KERNEL);
+	if (!gd.toc)
+		goto probe_fail_toc;
+	add_disk(gd.disk);
+	return 0;
+
+probe_fail_toc:
+	blk_cleanup_queue(gd.gdrom_rq);
+probe_fail_requestq:
+	free_irq(HW_EVENT_GDROM_DMA, &gd);
+	free_irq(HW_EVENT_GDROM_CMD, &gd);
+probe_fail_cmdirq_register:
+probe_fail_cdrom_register:
+	del_gendisk(gd.disk);
+probe_fail_no_disk:
+	kfree(gd.cd_info);
+	unregister_blkdev(gdrom_major, GDROM_DEV_NAME);
+	gdrom_major = 0;
+probe_fail_no_mem:
+	printk(KERN_WARNING "GDROM: Could not probe for device - error is 0x%X\n", err);
+	return err;
+}
+
+static int remove_gdrom(struct platform_device *devptr)
+{
+	blk_cleanup_queue(gd.gdrom_rq);
+	free_irq(HW_EVENT_GDROM_CMD, &gd);
+	free_irq(HW_EVENT_GDROM_DMA, &gd);
+	del_gendisk(gd.disk);
+	if (gdrom_major)
+		unregister_blkdev(gdrom_major, GDROM_DEV_NAME);
+	return unregister_cdrom(gd.cd_info);
+}
+
+static struct platform_driver gdrom_driver = {
+	.probe = probe_gdrom,
+	.remove = remove_gdrom,
+	.driver = {
+			.name = GDROM_DEV_NAME,
+	},
+};
+
+static int __init init_gdrom(void)
+{
+	int rc;
+	gd.toc = NULL;
+	rc = platform_driver_register(&gdrom_driver);
+	if (rc)
+		return rc;
+	pd = platform_device_register_simple(GDROM_DEV_NAME, -1, NULL, 0);
+	if (IS_ERR(pd)) {
+		platform_driver_unregister(&gdrom_driver);
+		return PTR_ERR(pd);
+	}
+	return 0;
+}
+
+static void __exit exit_gdrom(void)
+{
+	platform_device_unregister(pd);
+	platform_driver_unregister(&gdrom_driver);
+	kfree(gd.toc);
+}
+
+module_init(init_gdrom);
+module_exit(exit_gdrom);
+MODULE_AUTHOR("Adrian McMenamin <adrian@...en.demon.co.uk>");
+MODULE_DESCRIPTION("SEGA Dreamcast GD-ROM Driver");
+MODULE_LICENSE("GPL");
diff -rupN a/drivers/cdrom/Makefile b/drivers/cdrom/Makefile
--- a/drivers/cdrom/Makefile	2008-01-11 21:33:18.000000000 +0000
+++ b/drivers/cdrom/Makefile	2008-01-11 20:55:40.000000000 +0000
@@ -11,3 +11,4 @@ obj-$(CONFIG_PARIDE_PCD)	+=		cdrom.o
 obj-$(CONFIG_CDROM_PKTCDVD)	+=		cdrom.o
 
 obj-$(CONFIG_VIOCD)		+= viocd.o      cdrom.o
+obj-$(CONFIG_GDROM)		+= gdrom.o      cdrom.o



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