[PATCH] PPC64 iSeries virtual disk driver

From: Stephen Rothwell <sfr@canb.auug.org.au>

Add the PPC64 iSeries virtual disk driver

arch/ppc64/Kconfig

@@ -271,15 +271,6 @@ config VIODASD
 	  If you are running on an iSeries system and you want to use
  	  virtual disks created and managed by OS/400, say Y.
 
-config VIODASD_IDE
-	bool "iSeries Virtual disk IDE emulation"
-	depends on VIODASD
-	help
-	  This causes the iSeries virtual disks to look like IDE disks.
-	  If you have programs or utilities that only support certain
-	  kinds of disks, this option will cause iSeries virtual disks
-	  to pretend to be IDE disks, which may satisfy the program.
-
 config VIOCD
 	tristate "iSeries Virtual I/O CD support"
 	help

arch/ppc64/kernel/pci_dma.c

@@ -67,10 +67,10 @@ struct iSeries_Device_Node iSeries_veth_dev_node = { .LogicalSlot = 0xFF, .DevTc
 struct iSeries_Device_Node iSeries_vio_dev_node  = { .LogicalSlot = 0xFF, .DevTceTable = &virtBusVioTceTable };
 
 struct pci_dev    iSeries_veth_dev_st = { .sysdata = &iSeries_veth_dev_node };
-struct pci_dev    iSeries_vio_dev_st  = { .sysdata = &iSeries_vio_dev_node  };
+struct pci_dev    iSeries_vio_dev_st  = { .sysdata = &iSeries_vio_dev_node, .dev.bus = &pci_bus_type };
 
 struct pci_dev  * iSeries_veth_dev = &iSeries_veth_dev_st;
-struct pci_dev  * iSeries_vio_dev  = &iSeries_vio_dev_st;
+struct device  * iSeries_vio_dev  = &iSeries_vio_dev_st.dev;
 
 /* Device TceTable is stored in Device Node */
 /* struct TceTable * tceTables[256]; */	/* Tce tables for 256 busses

arch/ppc64/kernel/viopath.c

@@ -35,7 +35,8 @@
 #include <linux/vmalloc.h>
 #include <linux/string.h>
 #include <linux/proc_fs.h>
-#include <linux/pci.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
 #include <linux/wait.h>
 
 #include <asm/hardirq.h>	/* for is_atomic */
@@ -48,7 +49,7 @@
 #include <asm/iSeries/iSeries_proc.h>
 #include <asm/iSeries/vio.h>
 
-extern struct pci_dev *iSeries_vio_dev;
+extern struct device *iSeries_vio_dev;
 
 /* Status of the path to each other partition in the system.
  * This is overkill, since we will only ever establish connections
@@ -194,8 +195,7 @@ static int proc_read(char *buf, char **start, off_t offset,
 	HvLpEvent_Rc hvrc;
 	DECLARE_MUTEX_LOCKED(Semaphore);
 	dma_addr_t dmaa =
-	    pci_map_single(iSeries_vio_dev, buf, PAGE_SIZE,
-			   PCI_DMA_FROMDEVICE);
+	    dma_map_single(iSeries_vio_dev, buf, PAGE_SIZE, DMA_FROM_DEVICE);
 	int len = PAGE_SIZE;
 
 	if (len > blen)
@@ -215,8 +215,7 @@ static int proc_read(char *buf, char **start, off_t offset,
 
 	down(&Semaphore);
 
-	pci_unmap_single(iSeries_vio_dev, dmaa, PAGE_SIZE,
-			 PCI_DMA_FROMDEVICE);
+	dma_unmap_single(iSeries_vio_dev, dmaa, PAGE_SIZE, DMA_FROM_DEVICE);
 
 	sprintf(buf + strlen(buf), "SRLNBR=");
 	buf[strlen(buf)] = e2a(xItExtVpdPanel.mfgID[2]);

drivers/block/Makefile

@@ -38,3 +38,5 @@ obj-$(CONFIG_BLK_DEV_DAC960)	+= DAC960.o
 obj-$(CONFIG_BLK_DEV_UMEM)	+= umem.o
 obj-$(CONFIG_BLK_DEV_NBD)	+= nbd.o
 obj-$(CONFIG_BLK_DEV_CRYPTOLOOP) += cryptoloop.o
+
+obj-$(CONFIG_VIODASD)		+= viodasd.o

drivers/block/viodasd.c

+/* -*- linux-c -*-
+ * viodasd.c
+ *  Authors: Dave Boutcher <boutcher@us.ibm.com>
+ *           Ryan Arnold <ryanarn@us.ibm.com>
+ *           Colin Devilbiss <devilbis@us.ibm.com>
+ *           Stephen Rothwell <sfr@au1.ibm.com>
+ *
+ * (C) Copyright 2000-2004 IBM Corporation
+ *
+ * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * This routine provides access to disk space (termed "DASD" in historical
+ * IBM terms) owned and managed by an OS/400 partition running on the
+ * same box as this Linux partition.
+ *
+ * All disk operations are performed by sending messages back and forth to
+ * the OS/400 partition.
+ */
+#include <linux/major.h>
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/blkdev.h>
+#include <linux/genhd.h>
+#include <linux/hdreg.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/completion.h>
+
+#include <asm/uaccess.h>
+#include <asm/iSeries/HvTypes.h>
+#include <asm/iSeries/HvLpEvent.h>
+#include <asm/iSeries/HvLpConfig.h>
+#include <asm/iSeries/vio.h>
+
+MODULE_DESCRIPTION("iSeries Virtual DASD");
+MODULE_AUTHOR("Dave Boutcher");
+MODULE_LICENSE("GPL");
+
+/*
+ * We only support 7 partitions per physical disk....so with minor
+ * numbers 0-255 we get a maximum of 32 disks.
+ */
+#define VIOD_GENHD_NAME		"iseries/vd"
+#define VIOD_GENHD_DEVFS_NAME	"iseries/disc"
+
+#define VIOD_VERS		"1.64"
+
+#define VIOD_KERN_WARNING	KERN_WARNING "viod: "
+#define VIOD_KERN_INFO		KERN_INFO "viod: "
+
+enum {
+	PARTITION_SHIFT = 3,
+	MAX_DISKNO = 32,
+	MAX_DISK_NAME = sizeof(((struct gendisk *)0)->disk_name)
+};
+
+static int		viodasd_max_disk;
+static spinlock_t	viodasd_spinlock = SPIN_LOCK_UNLOCKED;
+
+#define VIOMAXREQ		16
+#define VIOMAXBLOCKDMA		12
+
+#define DEVICE_NO(cell)	((struct viodasd_device *)(cell) - &viodasd_devices[0])
+
+extern struct device *iSeries_vio_dev;
+
+struct open_data {
+	u64	disk_size;
+	u16	max_disk;
+	u16	cylinders;
+	u16	tracks;
+	u16	sectors;
+	u16	bytes_per_sector;
+};
+
+struct rw_data {
+	u64	offset;
+	struct {
+		u32	token;
+		u32	reserved;
+		u64	len;
+	} dma_info[VIOMAXBLOCKDMA];
+};
+
+struct vioblocklpevent {
+	struct HvLpEvent	event;
+	u32			reserved;
+	u16			version;
+	u16			sub_result;
+	u16			disk;
+	u16			flags;
+	union {
+		struct open_data	open_data;
+		struct rw_data		rw_data;
+		u64			changed;
+	} u;
+};
+
+#define vioblockflags_ro   0x0001
+
+enum vioblocksubtype {
+	vioblockopen = 0x0001,
+	vioblockclose = 0x0002,
+	vioblockread = 0x0003,
+	vioblockwrite = 0x0004,
+	vioblockflush = 0x0005,
+	vioblockcheck = 0x0007
+};
+
+struct viodasd_waitevent {
+	struct completion	com;
+	int			rc;
+	u16			sub_result;
+	int			max_disk;	/* open */
+};
+
+static const struct vio_error_entry viodasd_err_table[] = {
+	{ 0x0201, EINVAL, "Invalid Range" },
+	{ 0x0202, EINVAL, "Invalid Token" },
+	{ 0x0203, EIO, "DMA Error" },
+	{ 0x0204, EIO, "Use Error" },
+	{ 0x0205, EIO, "Release Error" },
+	{ 0x0206, EINVAL, "Invalid Disk" },
+	{ 0x0207, EBUSY, "Cant Lock" },
+	{ 0x0208, EIO, "Already Locked" },
+	{ 0x0209, EIO, "Already Unlocked" },
+	{ 0x020A, EIO, "Invalid Arg" },
+	{ 0x020B, EIO, "Bad IFS File" },
+	{ 0x020C, EROFS, "Read Only Device" },
+	{ 0x02FF, EIO, "Internal Error" },
+	{ 0x0000, 0, NULL },
+};
+
+/*
+ * Figure out the biggest I/O request (in sectors) we can accept
+ */
+#define VIODASD_MAXSECTORS (4096 / 512 * VIOMAXBLOCKDMA)
+
+/*
+ * Number of disk I/O requests we've sent to OS/400
+ */
+static int num_req_outstanding;
+
+/*
+ * This is our internal structure for keeping track of disk devices
+ */
+struct viodasd_device {
+	u16		cylinders;
+	u16		tracks;
+	u16		sectors;
+	u16		bytes_per_sector;
+	u64		size;
+	int		read_only;
+	spinlock_t	q_lock;
+	struct gendisk	*disk;
+} viodasd_devices[MAX_DISKNO];
+
+/*
+ * External open entry point.
+ */
+static int viodasd_open(struct inode *ino, struct file *fil)
+{
+	struct viodasd_device *d = ino->i_bdev->bd_disk->private_data;
+	HvLpEvent_Rc hvrc;
+	struct viodasd_waitevent we;
+
+	init_completion(&we.com);
+
+	/* Send the open event to OS/400 */
+	hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
+			HvLpEvent_Type_VirtualIo,
+			viomajorsubtype_blockio | vioblockopen,
+			HvLpEvent_AckInd_DoAck, HvLpEvent_AckType_ImmediateAck,
+			viopath_sourceinst(viopath_hostLp),
+			viopath_targetinst(viopath_hostLp),
+			(u64)(unsigned long)&we, VIOVERSION << 16,
+			((u64)DEVICE_NO(d) << 48) /* | ((u64)flags << 32) */,
+			0, 0, 0);
+	if (hvrc != 0) {
+		printk(VIOD_KERN_WARNING "HV open failed %d\n", (int)hvrc);
+		return -EIO;
+	}
+
+	wait_for_completion(&we.com);
+
+	/* Check the return code */
+	if (we.rc != 0) {
+		const struct vio_error_entry *err =
+			vio_lookup_rc(viodasd_err_table, we.sub_result);
+
+		printk(VIOD_KERN_WARNING
+				"bad rc opening disk: %d:0x%04x (%s)\n",
+				(int)we.rc, we.sub_result, err->msg);
+		return -EIO;
+	}
+	viodasd_max_disk = we.max_disk;
+
+	return 0;
+}
+
+/*
+ * External release entry point.
+ */
+static int viodasd_release(struct inode *ino, struct file *fil)
+{
+	struct viodasd_device *d = ino->i_bdev->bd_disk->private_data;
+	HvLpEvent_Rc hvrc;
+
+	/* Send the event to OS/400.  We DON'T expect a response */
+	hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
+			HvLpEvent_Type_VirtualIo,
+			viomajorsubtype_blockio | vioblockclose,
+			HvLpEvent_AckInd_NoAck, HvLpEvent_AckType_ImmediateAck,
+			viopath_sourceinst(viopath_hostLp),
+			viopath_targetinst(viopath_hostLp),
+			0, VIOVERSION << 16,
+			((u64)DEVICE_NO(d) << 48) /* | ((u64)flags << 32) */,
+			0, 0, 0);
+	if (hvrc != 0)
+		printk(VIOD_KERN_WARNING "HV close call failed %d\n",
+				(int)hvrc);
+	return 0;
+}
+
+
+/* External ioctl entry point.
+ */
+static int viodasd_ioctl(struct inode *ino, struct file *fil,
+			 unsigned int cmd, unsigned long arg)
+{
+	int err;
+	unsigned char sectors;
+	unsigned char heads;
+	unsigned short cylinders;
+	struct hd_geometry *geo;
+	struct gendisk *gendisk;
+	struct viodasd_device *d;
+
+	switch (cmd) {
+	case HDIO_GETGEO:
+		geo = (struct hd_geometry *)arg;
+		if (geo == NULL)
+			return -EINVAL;
+		err = verify_area(VERIFY_WRITE, geo, sizeof(*geo));
+		if (err)
+			return err;
+		gendisk = ino->i_bdev->bd_disk;
+		d = gendisk->private_data;
+		sectors = d->sectors;
+		if (sectors == 0)
+			sectors = 32;
+		heads = d->tracks;
+		if (heads == 0)
+			heads = 64;
+		cylinders = d->cylinders;
+		if (cylinders == 0)
+			cylinders = get_capacity(gendisk) / (sectors * heads);
+		if (__put_user(sectors, &geo->sectors) ||
+		    __put_user(heads, &geo->heads) ||
+		    __put_user(cylinders, &geo->cylinders) ||
+		    __put_user(get_start_sect(ino->i_bdev), &geo->start))
+			return -EFAULT;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+/*
+ * Our file operations table
+ */
+static struct block_device_operations viodasd_fops = {
+	.owner = THIS_MODULE,
+	.open = viodasd_open,
+	.release = viodasd_release,
+	.ioctl = viodasd_ioctl,
+};
+
+/*
+ * End a request
+ */
+static void viodasd_end_request(struct request *req, int uptodate,
+		int num_sectors)
+{
+	if (end_that_request_first(req, uptodate, num_sectors))
+		return;
+	add_disk_randomness(req->rq_disk);
+	end_that_request_last(req);
+}
+
+/*
+ * Send an actual I/O request to OS/400
+ */
+static int send_request(struct request *req)
+{
+	u64 start;
+	int direction;
+	int nsg;
+	u16 viocmd;
+	HvLpEvent_Rc hvrc;
+	struct vioblocklpevent *bevent;
+	struct scatterlist sg[VIOMAXBLOCKDMA];
+	int sgindex;
+	int statindex;
+	struct viodasd_device *d;
+	unsigned long flags;
+
+	start = (u64)req->sector << 9;
+
+	if (rq_data_dir(req) == READ) {
+		direction = DMA_FROM_DEVICE;
+		viocmd = viomajorsubtype_blockio | vioblockread;
+		statindex = 0;
+	} else {
+		direction = DMA_TO_DEVICE;
+		viocmd = viomajorsubtype_blockio | vioblockwrite;
+		statindex = 1;
+	}
+
+        d = req->rq_disk->private_data;
+
+	/* Now build the scatter-gather list */
+	nsg = blk_rq_map_sg(req->q, req, sg);
+	nsg = dma_map_sg(iSeries_vio_dev, sg, nsg, direction);
+
+	spin_lock_irqsave(&viodasd_spinlock, flags);
+	num_req_outstanding++;
+
+	/* This optimization handles a single DMA block */
+	if (nsg == 1)
+		hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
+				HvLpEvent_Type_VirtualIo, viocmd,
+				HvLpEvent_AckInd_DoAck,
+				HvLpEvent_AckType_ImmediateAck,
+				viopath_sourceinst(viopath_hostLp),
+				viopath_targetinst(viopath_hostLp),
+				(u64)(unsigned long)req, VIOVERSION << 16,
+				((u64)DEVICE_NO(d) << 48), start,
+				((u64)sg_dma_address(&sg[0])) << 32,
+				sg_dma_len(&sg[0]));
+	else {
+		bevent = (struct vioblocklpevent *)
+			vio_get_event_buffer(viomajorsubtype_blockio);
+		if (bevent == NULL) {
+			printk(VIOD_KERN_WARNING
+			       "error allocating disk event buffer\n");
+			goto error_ret;
+		}
+
+		/*
+		 * Now build up the actual request.  Note that we store
+		 * the pointer to the request in the correlation
+		 * token so we can match the response up later
+		 */
+		memset(bevent, 0, sizeof(struct vioblocklpevent));
+		bevent->event.xFlags.xValid = 1;
+		bevent->event.xFlags.xFunction = HvLpEvent_Function_Int;
+		bevent->event.xFlags.xAckInd = HvLpEvent_AckInd_DoAck;
+		bevent->event.xFlags.xAckType = HvLpEvent_AckType_ImmediateAck;
+		bevent->event.xType = HvLpEvent_Type_VirtualIo;
+		bevent->event.xSubtype = viocmd;
+		bevent->event.xSourceLp = HvLpConfig_getLpIndex();
+		bevent->event.xTargetLp = viopath_hostLp;
+		bevent->event.xSizeMinus1 =
+			offsetof(struct vioblocklpevent, u.rw_data.dma_info) +
+			(sizeof(bevent->u.rw_data.dma_info[0]) * nsg) - 1;
+		bevent->event.xSourceInstanceId =
+			viopath_sourceinst(viopath_hostLp);
+		bevent->event.xTargetInstanceId =
+			viopath_targetinst(viopath_hostLp);
+		bevent->event.xCorrelationToken = (u64)req;
+		bevent->version = VIOVERSION;
+		bevent->disk = DEVICE_NO(d);
+		bevent->u.rw_data.offset = start;
+
+		/*
+		 * Copy just the dma information from the sg list
+		 * into the request
+		 */
+		for (sgindex = 0; sgindex < nsg; sgindex++) {
+			bevent->u.rw_data.dma_info[sgindex].token =
+				sg_dma_address(&sg[sgindex]);
+			bevent->u.rw_data.dma_info[sgindex].len =
+				sg_dma_len(&sg[sgindex]);
+		}
+
+		/* Send the request */
+		hvrc = HvCallEvent_signalLpEvent(&bevent->event);
+		vio_free_event_buffer(viomajorsubtype_blockio, bevent);
+	}
+
+	if (hvrc != HvLpEvent_Rc_Good) {
+		printk(VIOD_KERN_WARNING
+		       "error sending disk event to OS/400 (rc %d)\n",
+		       (int)hvrc);
+		goto error_ret;
+	}
+	spin_unlock_irqrestore(&viodasd_spinlock, flags);
+	return 0;
+
+error_ret:
+	num_req_outstanding--;
+	spin_unlock_irqrestore(&viodasd_spinlock, flags);
+	dma_unmap_sg(iSeries_vio_dev, sg, nsg, direction);
+	return -1;
+}
+
+/*
+ * This is the external request processing routine
+ */
+static void do_viodasd_request(request_queue_t *q)
+{
+	struct request *req;
+
+	/*
+	 * If we already have the maximum number of requests
+	 * outstanding to OS/400 just bail out. We'll come
+	 * back later.
+	 */
+	while (num_req_outstanding < VIOMAXREQ) {
+		req = elv_next_request(q);
+		if (req == NULL)
+			return;
+		/* dequeue the current request from the queue */
+		blkdev_dequeue_request(req);
+		/* check that request contains a valid command */
+		if (!blk_fs_request(req)) {
+			viodasd_end_request(req, 0, req->hard_nr_sectors);
+			continue;
+		}
+		/* Try sending the request */
+		if (send_request(req) != 0)
+			viodasd_end_request(req, 0, req->hard_nr_sectors);
+	}
+}
+
+/*
+ * Probe a single disk and fill in the viodasd_device structure
+ * for it.
+ */
+static void probe_disk(struct viodasd_device *d)
+{
+	HvLpEvent_Rc hvrc;
+	struct viodasd_waitevent we;
+	int dev_no = DEVICE_NO(d);
+	struct gendisk *g;
+	struct request_queue *q;
+
+	init_completion(&we.com);
+
+	/* Send the open event to OS/400 */
+	hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
+			HvLpEvent_Type_VirtualIo,
+			viomajorsubtype_blockio | vioblockopen,
+			HvLpEvent_AckInd_DoAck, HvLpEvent_AckType_ImmediateAck,
+			viopath_sourceinst(viopath_hostLp),
+			viopath_targetinst(viopath_hostLp),
+			(u64)(unsigned long)&we, VIOVERSION << 16,
+			((u64)dev_no << 48) | ((u64)vioblockflags_ro << 32),
+			0, 0, 0);
+	if (hvrc != 0) {
+		printk(VIOD_KERN_WARNING "bad rc on HV open %d\n", (int)hvrc);
+		return;
+	}
+
+	wait_for_completion(&we.com);
+
+	if (we.rc != 0)
+		return;
+	viodasd_max_disk = we.max_disk;
+
+	/* Send the close event to OS/400.  We DON'T expect a response */
+	hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
+			HvLpEvent_Type_VirtualIo,
+			viomajorsubtype_blockio | vioblockclose,
+			HvLpEvent_AckInd_NoAck, HvLpEvent_AckType_ImmediateAck,
+			viopath_sourceinst(viopath_hostLp),
+			viopath_targetinst(viopath_hostLp),
+			0, VIOVERSION << 16,
+			((u64)dev_no << 48) | ((u64)vioblockflags_ro << 32),
+			0, 0, 0);
+	if (hvrc != 0) {
+		printk(VIOD_KERN_WARNING
+		       "bad rc sending event to OS/400 %d\n", (int)hvrc);
+		return;
+	}
+	printk(VIOD_KERN_INFO "disk %d: %lu sectors (%lu MB) "
+			"CHS=%d/%d/%d sector size %d\n",
+			dev_no, (unsigned long)(d->size >> 9),
+			(unsigned long)(d->size >> 20),
+			(int)d->cylinders, (int)d->tracks,
+			(int)d->sectors, (int)d->bytes_per_sector);
+	/* create the request queue for the disk */
+	spin_lock_init(&d->q_lock);
+	q = blk_init_queue(do_viodasd_request, &d->q_lock);
+	if (q == NULL) {
+		printk(VIOD_KERN_WARNING "cannot allocate queue for disk %d\n",
+				dev_no);
+		return;
+	}
+	g = alloc_disk(1 << PARTITION_SHIFT);
+	if (g == NULL) {
+		printk(VIOD_KERN_WARNING
+				"cannot allocate disk structure for disk %d\n",
+				dev_no);
+		blk_cleanup_queue(q);
+		return;
+	}
+
+	d->disk = g;
+	blk_queue_max_hw_segments(q, VIOMAXBLOCKDMA);
+	blk_queue_max_phys_segments(q, VIOMAXBLOCKDMA);
+	blk_queue_max_sectors(q, VIODASD_MAXSECTORS);
+	g->major = VIODASD_MAJOR;
+	g->first_minor = dev_no << PARTITION_SHIFT;
+	if (dev_no >= 26)
+		snprintf(g->disk_name, sizeof(g->disk_name),
+				VIOD_GENHD_NAME "%c%c",
+				'a' + (dev_no / 26) - 1, 'a' + (dev_no % 26));
+	else
+		snprintf(g->disk_name, sizeof(g->disk_name),
+				VIOD_GENHD_NAME "%c", 'a' + (dev_no % 26));
+	snprintf(g->devfs_name, sizeof(g->devfs_name),
+			"%s%d", VIOD_GENHD_DEVFS_NAME, dev_no);
+	g->fops = &viodasd_fops;
+	g->queue = q;
+	g->private_data = d;
+	set_capacity(g, d->size >> 9);
+
+	/* register us in the global list */
+	add_disk(g);
+}
+
+/* returns the total number of scatterlist elements converted */
+static int block_event_to_scatterlist(const struct vioblocklpevent *bevent,
+		struct scatterlist *sg, int *total_len)
+{
+	int i, numsg;
+	const struct rw_data *rw_data = &bevent->u.rw_data;
+	static const int offset =
+		offsetof(struct vioblocklpevent, u.rw_data.dma_info);
+	static const int element_size = sizeof(rw_data->dma_info[0]);
+
+	numsg = ((bevent->event.xSizeMinus1 + 1) - offset) / element_size;
+	if (numsg > VIOMAXBLOCKDMA)
+		numsg = VIOMAXBLOCKDMA;
+
+	*total_len = 0;
+	memset(sg, 0, sizeof(sg[0]) * VIOMAXBLOCKDMA);
+
+	for (i = 0; (i < numsg) && (rw_data->dma_info[i].len > 0); ++i) {
+		sg_dma_address(&sg[i]) = rw_data->dma_info[i].token;
+		sg_dma_len(&sg[i]) = rw_data->dma_info[i].len;
+		*total_len += rw_data->dma_info[i].len;
+	}
+	return i;
+}
+
+/*
+ * Restart all queues, starting with the one _after_ the disk given,
+ * thus reducing the chance of starvation of higher numbered disks.
+ */
+static void viodasd_restart_all_queues_starting_from(int first_index)
+{
+	int i;
+
+	for (i = first_index + 1; i < MAX_DISKNO; ++i)
+		if (viodasd_devices[i].disk)
+			blk_run_queue(viodasd_devices[i].disk->queue);
+	for (i = 0; i <= first_index; ++i)
+		if (viodasd_devices[i].disk)
+			blk_run_queue(viodasd_devices[i].disk->queue);
+}
+
+/*
+ * For read and write requests, decrement the number of outstanding requests,
+ * Free the DMA buffers we allocated.
+ */
+static int viodasd_handle_read_write(struct vioblocklpevent *bevent)
+{
+	int num_sg, num_sect, pci_direction, total_len;
+	struct request *req;
+	struct scatterlist sg[VIOMAXBLOCKDMA];
+	struct HvLpEvent *event = &bevent->event;
+	unsigned long irq_flags;
+	int device_no;
+	int error;
+	spinlock_t *qlock;
+
+	num_sg = block_event_to_scatterlist(bevent, sg, &total_len);
+	num_sect = total_len >> 9;
+	if (event->xSubtype == (viomajorsubtype_blockio | vioblockread))
+		pci_direction = DMA_FROM_DEVICE;
+	else
+		pci_direction = DMA_TO_DEVICE;
+	dma_unmap_sg(iSeries_vio_dev, sg, num_sg, pci_direction);
+
+	/*
+	 * Since this is running in interrupt mode, we need to make sure
+	 * we're not stepping on any global I/O operations
+	 */
+	spin_lock_irqsave(&viodasd_spinlock, irq_flags);
+	num_req_outstanding--;
+	spin_unlock_irqrestore(&viodasd_spinlock, irq_flags);
+
+	req = (struct request *)bevent->event.xCorrelationToken;
+	device_no = DEVICE_NO(req->rq_disk->private_data);
+
+	error = event->xRc != HvLpEvent_Rc_Good;
+	if (error) {
+		const struct vio_error_entry *err;
+		err = vio_lookup_rc(viodasd_err_table, bevent->sub_result);
+		printk(VIOD_KERN_WARNING "read/write error %d:0x%04x (%s)\n",
+				event->xRc, bevent->sub_result, err->msg);
+		num_sect = req->hard_nr_sectors;
+	}
+	qlock = req->q->queue_lock;
+	spin_lock_irqsave(qlock, irq_flags);
+	viodasd_end_request(req, !error, num_sect);
+	spin_unlock_irqrestore(qlock, irq_flags);
+
+	/* Finally, try to get more requests off of this device's queue */
+	viodasd_restart_all_queues_starting_from(device_no);
+
+	return 0;
+}
+
+/* This routine handles incoming block LP events */
+static void handle_block_event(struct HvLpEvent *event)
+{
+	struct vioblocklpevent *bevent = (struct vioblocklpevent *)event;
+	struct viodasd_waitevent *pwe;
+
+	if (event == NULL)
+		/* Notification that a partition went away! */
+		return;
+	/* First, we should NEVER get an int here...only acks */
+	if (event->xFlags.xFunction == HvLpEvent_Function_Int) {
+		printk(VIOD_KERN_WARNING
+		       "Yikes! got an int in viodasd event handler!\n");
+		if (event->xFlags.xAckInd == HvLpEvent_AckInd_DoAck) {
+			event->xRc = HvLpEvent_Rc_InvalidSubtype;
+			HvCallEvent_ackLpEvent(event);
+		}
+	}
+
+	switch (event->xSubtype & VIOMINOR_SUBTYPE_MASK) {
+	case vioblockopen:
+		/*
+		 * Handle a response to an open request.  We get all the
+		 * disk information in the response, so update it.  The
+		 * correlation token contains a pointer to a waitevent
+		 * structure that has a completion in it.  update the
+		 * return code in the waitevent structure and post the
+		 * completion to wake up the guy who sent the request
+		 */
+		pwe = (struct viodasd_waitevent *)event->xCorrelationToken;
+		pwe->rc = event->xRc;
+		pwe->sub_result = bevent->sub_result;
+		if (event->xRc == HvLpEvent_Rc_Good) {
+			const struct open_data *data = &bevent->u.open_data;
+			struct viodasd_device *device =
+				&viodasd_devices[bevent->disk];
+			device->read_only =
+				bevent->flags & vioblockflags_ro;
+			device->size = data->disk_size;
+			device->cylinders = data->cylinders;
+			device->tracks = data->tracks;
+			device->sectors = data->sectors;
+			device->bytes_per_sector = data->bytes_per_sector;
+			pwe->max_disk = data->max_disk;
+		}
+		complete(&pwe->com);
+		break;
+	case vioblockclose:
+		break;
+	case vioblockread:
+	case vioblockwrite:
+		viodasd_handle_read_write(bevent);
+		break;
+
+	default:
+		printk(VIOD_KERN_WARNING "invalid subtype!");
+		if (event->xFlags.xAckInd == HvLpEvent_AckInd_DoAck) {
+			event->xRc = HvLpEvent_Rc_InvalidSubtype;
+			HvCallEvent_ackLpEvent(event);
+		}
+	}
+}
+
+/*
+ * Initialize the whole device driver.  Handle module and non-module
+ * versions
+ */
+static int __init viodasd_init(void)
+{
+	int i;
+
+	/* Try to open to our host lp */
+	if (viopath_hostLp == HvLpIndexInvalid)
+		vio_set_hostlp();
+
+	if (viopath_hostLp == HvLpIndexInvalid) {
+		printk(VIOD_KERN_WARNING "invalid hosting partition\n");
+		return -EIO;
+	}
+
+	printk(VIOD_KERN_INFO "vers " VIOD_VERS ", hosting partition %d\n",
+			viopath_hostLp);
+
+        /* register the block device */
+	if (register_blkdev(VIODASD_MAJOR, VIOD_GENHD_NAME)) {
+		printk(VIOD_KERN_WARNING
+				"Unable to get major number %d for %s\n",
+				VIODASD_MAJOR, VIOD_GENHD_NAME);
+		return -EIO;
+	}
+	/* Actually open the path to the hosting partition */
+	if (viopath_open(viopath_hostLp, viomajorsubtype_blockio,
+				VIOMAXREQ + 2)) {
+		printk(VIOD_KERN_WARNING
+		       "error opening path to host partition %d\n",
+		       viopath_hostLp);
+		unregister_blkdev(VIODASD_MAJOR, VIOD_GENHD_NAME);
+		return -EIO;
+	}
+
+	/* Initialize our request handler */
+	vio_setHandler(viomajorsubtype_blockio, handle_block_event);
+
+	viodasd_max_disk = MAX_DISKNO - 1;
+	for (i = 0; (i <= viodasd_max_disk) && (i < MAX_DISKNO); i++) {
+		/*
+		 * Note that probe_disk has side effects:
+		 *  a) it updates the size of the disk
+		 *  b) it updates viodasd_max_disk
+		 *  c) it registers the disk if it has not done so already
+		 */
+		probe_disk(&viodasd_devices[i]);
+	}
+
+	if (viodasd_max_disk > (MAX_DISKNO - 1))
+		printk(VIOD_KERN_INFO
+			"Only examining the first %d of %d disks connected\n",
+			MAX_DISKNO, viodasd_max_disk + 1);
+
+	return 0;
+}
+module_init(viodasd_init);
+
+void viodasd_exit(void)
+{
+	int i;
+	struct viodasd_device *d;
+
+        for (i = 0; i < MAX_DISKNO; i++) {
+		d = &viodasd_devices[i];
+		if (d->disk) {
+			del_gendisk(d->disk);
+			put_disk(d->disk);
+			blk_cleanup_queue(d->disk->queue);
+			d->disk = NULL;
+		}
+	}
+	vio_clearHandler(viomajorsubtype_blockio);
+	unregister_blkdev(VIODASD_MAJOR, VIOD_GENHD_NAME);
+	viopath_close(viopath_hostLp, viomajorsubtype_blockio, VIOMAXREQ + 2);
+}
+
+module_exit(viodasd_exit);

include/linux/major.h

@@ -126,6 +126,9 @@
 #define COMPAQ_CISS_MAJOR6      110
 #define COMPAQ_CISS_MAJOR7      111
 
+#define VIODASD_MAJOR		112
+#define VIOCD_MAJOR		113
+
 #define ATARAID_MAJOR		114
 
 #define SCSI_DISK8_MAJOR	128