Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 932 insertions, 0 deletions

diff --git a/drivers/virt/fsl_hypervisor.c b/drivers/virt/fsl_hypervisor.c
new file mode 100644
index 000000000..07035249a
--- /dev/null
+++ b/drivers/virt/fsl_hypervisor.c
@@ -0,0 +1,932 @@
+/*
+ * Freescale Hypervisor Management Driver
+
+ * Copyright (C) 2008-2011 Freescale Semiconductor, Inc.
+ * Author: Timur Tabi <timur@freescale.com>
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2.  This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ *
+ * The Freescale hypervisor management driver provides several services to
+ * drivers and applications related to the Freescale hypervisor:
+ *
+ * 1. An ioctl interface for querying and managing partitions.
+ *
+ * 2. A file interface to reading incoming doorbells.
+ *
+ * 3. An interrupt handler for shutting down the partition upon receiving the
+ *    shutdown doorbell from a manager partition.
+ *
+ * 4. A kernel interface for receiving callbacks when a managed partition
+ *    shuts down.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/err.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/poll.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/reboot.h>
+#include <linux/uaccess.h>
+#include <linux/notifier.h>
+#include <linux/interrupt.h>
+
+#include <linux/io.h>
+#include <asm/fsl_hcalls.h>
+
+#include <linux/fsl_hypervisor.h>
+
+static BLOCKING_NOTIFIER_HEAD(failover_subscribers);
+
+/*
+ * Ioctl interface for FSL_HV_IOCTL_PARTITION_RESTART
+ *
+ * Restart a running partition
+ */
+static long ioctl_restart(struct fsl_hv_ioctl_restart __user *p)
+{
+	struct fsl_hv_ioctl_restart param;
+
+	/* Get the parameters from the user */
+	if (copy_from_user(&param, p, sizeof(struct fsl_hv_ioctl_restart)))
+		return -EFAULT;
+
+	param.ret = fh_partition_restart(param.partition);
+
+	if (copy_to_user(&p->ret, &param.ret, sizeof(__u32)))
+		return -EFAULT;
+
+	return 0;
+}
+
+/*
+ * Ioctl interface for FSL_HV_IOCTL_PARTITION_STATUS
+ *
+ * Query the status of a partition
+ */
+static long ioctl_status(struct fsl_hv_ioctl_status __user *p)
+{
+	struct fsl_hv_ioctl_status param;
+	u32 status;
+
+	/* Get the parameters from the user */
+	if (copy_from_user(&param, p, sizeof(struct fsl_hv_ioctl_status)))
+		return -EFAULT;
+
+	param.ret = fh_partition_get_status(param.partition, &status);
+	if (!param.ret)
+		param.status = status;
+
+	if (copy_to_user(p, &param, sizeof(struct fsl_hv_ioctl_status)))
+		return -EFAULT;
+
+	return 0;
+}
+
+/*
+ * Ioctl interface for FSL_HV_IOCTL_PARTITION_START
+ *
+ * Start a stopped partition.
+ */
+static long ioctl_start(struct fsl_hv_ioctl_start __user *p)
+{
+	struct fsl_hv_ioctl_start param;
+
+	/* Get the parameters from the user */
+	if (copy_from_user(&param, p, sizeof(struct fsl_hv_ioctl_start)))
+		return -EFAULT;
+
+	param.ret = fh_partition_start(param.partition, param.entry_point,
+				       param.load);
+
+	if (copy_to_user(&p->ret, &param.ret, sizeof(__u32)))
+		return -EFAULT;
+
+	return 0;
+}
+
+/*
+ * Ioctl interface for FSL_HV_IOCTL_PARTITION_STOP
+ *
+ * Stop a running partition
+ */
+static long ioctl_stop(struct fsl_hv_ioctl_stop __user *p)
+{
+	struct fsl_hv_ioctl_stop param;
+
+	/* Get the parameters from the user */
+	if (copy_from_user(&param, p, sizeof(struct fsl_hv_ioctl_stop)))
+		return -EFAULT;
+
+	param.ret = fh_partition_stop(param.partition);
+
+	if (copy_to_user(&p->ret, &param.ret, sizeof(__u32)))
+		return -EFAULT;
+
+	return 0;
+}
+
+/*
+ * Ioctl interface for FSL_HV_IOCTL_MEMCPY
+ *
+ * The FH_MEMCPY hypercall takes an array of address/address/size structures
+ * to represent the data being copied.  As a convenience to the user, this
+ * ioctl takes a user-create buffer and a pointer to a guest physically
+ * contiguous buffer in the remote partition, and creates the
+ * address/address/size array for the hypercall.
+ */
+static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
+{
+	struct fsl_hv_ioctl_memcpy param;
+
+	struct page **pages = NULL;
+	void *sg_list_unaligned = NULL;
+	struct fh_sg_list *sg_list = NULL;
+
+	unsigned int num_pages;
+	unsigned long lb_offset; /* Offset within a page of the local buffer */
+
+	unsigned int i;
+	long ret = 0;
+	int num_pinned = 0; /* return value from get_user_pages_fast() */
+	phys_addr_t remote_paddr; /* The next address in the remote buffer */
+	uint32_t count; /* The number of bytes left to copy */
+
+	/* Get the parameters from the user */
+	if (copy_from_user(&param, p, sizeof(struct fsl_hv_ioctl_memcpy)))
+		return -EFAULT;
+
+	/*
+	 * One partition must be local, the other must be remote.  In other
+	 * words, if source and target are both -1, or are both not -1, then
+	 * return an error.
+	 */
+	if ((param.source == -1) == (param.target == -1))
+		return -EINVAL;
+
+	/*
+	 * The array of pages returned by get_user_pages_fast() covers only
+	 * page-aligned memory.  Since the user buffer is probably not
+	 * page-aligned, we need to handle the discrepancy.
+	 *
+	 * We calculate the offset within a page of the S/G list, and make
+	 * adjustments accordingly.  This will result in a page list that looks
+	 * like this:
+	 *
+	 *      ----    <-- first page starts before the buffer
+	 *     |    |
+	 *     |////|-> ----
+	 *     |////|  |    |
+	 *      ----   |    |
+	 *             |    |
+	 *      ----   |    |
+	 *     |////|  |    |
+	 *     |////|  |    |
+	 *     |////|  |    |
+	 *      ----   |    |
+	 *             |    |
+	 *      ----   |    |
+	 *     |////|  |    |
+	 *     |////|  |    |
+	 *     |////|  |    |
+	 *      ----   |    |
+	 *             |    |
+	 *      ----   |    |
+	 *     |////|  |    |
+	 *     |////|-> ----
+	 *     |    |   <-- last page ends after the buffer
+	 *      ----
+	 *
+	 * The distance between the start of the first page and the start of the
+	 * buffer is lb_offset.  The hashed (///) areas are the parts of the
+	 * page list that contain the actual buffer.
+	 *
+	 * The advantage of this approach is that the number of pages is
+	 * equal to the number of entries in the S/G list that we give to the
+	 * hypervisor.
+	 */
+	lb_offset = param.local_vaddr & (PAGE_SIZE - 1);
+	if (param.count == 0 ||
+	    param.count > U64_MAX - lb_offset - PAGE_SIZE + 1)
+		return -EINVAL;
+	num_pages = (param.count + lb_offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+	/* Allocate the buffers we need */
+
+	/*
+	 * 'pages' is an array of struct page pointers that's initialized by
+	 * get_user_pages_fast().
+	 */
+	pages = kcalloc(num_pages, sizeof(struct page *), GFP_KERNEL);
+	if (!pages) {
+		pr_debug("fsl-hv: could not allocate page list\n");
+		return -ENOMEM;
+	}
+
+	/*
+	 * sg_list is the list of fh_sg_list objects that we pass to the
+	 * hypervisor.
+	 */
+	sg_list_unaligned = kmalloc(num_pages * sizeof(struct fh_sg_list) +
+		sizeof(struct fh_sg_list) - 1, GFP_KERNEL);
+	if (!sg_list_unaligned) {
+		pr_debug("fsl-hv: could not allocate S/G list\n");
+		ret = -ENOMEM;
+		goto free_pages;
+	}
+	sg_list = PTR_ALIGN(sg_list_unaligned, sizeof(struct fh_sg_list));
+
+	/* Get the physical addresses of the source buffer */
+	num_pinned = get_user_pages_fast(param.local_vaddr - lb_offset,
+		num_pages, param.source != -1 ? FOLL_WRITE : 0, pages);
+
+	if (num_pinned != num_pages) {
+		pr_debug("fsl-hv: could not lock source buffer\n");
+		ret = (num_pinned < 0) ? num_pinned : -EFAULT;
+		goto exit;
+	}
+
+	/*
+	 * Build the fh_sg_list[] array.  The first page is special
+	 * because it's misaligned.
+	 */
+	if (param.source == -1) {
+		sg_list[0].source = page_to_phys(pages[0]) + lb_offset;
+		sg_list[0].target = param.remote_paddr;
+	} else {
+		sg_list[0].source = param.remote_paddr;
+		sg_list[0].target = page_to_phys(pages[0]) + lb_offset;
+	}
+	sg_list[0].size = min_t(uint64_t, param.count, PAGE_SIZE - lb_offset);
+
+	remote_paddr = param.remote_paddr + sg_list[0].size;
+	count = param.count - sg_list[0].size;
+
+	for (i = 1; i < num_pages; i++) {
+		if (param.source == -1) {
+			/* local to remote */
+			sg_list[i].source = page_to_phys(pages[i]);
+			sg_list[i].target = remote_paddr;
+		} else {
+			/* remote to local */
+			sg_list[i].source = remote_paddr;
+			sg_list[i].target = page_to_phys(pages[i]);
+		}
+		sg_list[i].size = min_t(uint64_t, count, PAGE_SIZE);
+
+		remote_paddr += sg_list[i].size;
+		count -= sg_list[i].size;
+	}
+
+	param.ret = fh_partition_memcpy(param.source, param.target,
+		virt_to_phys(sg_list), num_pages);
+
+exit:
+	if (pages && (num_pinned > 0)) {
+		for (i = 0; i < num_pinned; i++)
+			put_page(pages[i]);
+	}
+
+	kfree(sg_list_unaligned);
+free_pages:
+	kfree(pages);
+
+	if (!ret)
+		if (copy_to_user(&p->ret, &param.ret, sizeof(__u32)))
+			return -EFAULT;
+
+	return ret;
+}
+
+/*
+ * Ioctl interface for FSL_HV_IOCTL_DOORBELL
+ *
+ * Ring a doorbell
+ */
+static long ioctl_doorbell(struct fsl_hv_ioctl_doorbell __user *p)
+{
+	struct fsl_hv_ioctl_doorbell param;
+
+	/* Get the parameters from the user. */
+	if (copy_from_user(&param, p, sizeof(struct fsl_hv_ioctl_doorbell)))
+		return -EFAULT;
+
+	param.ret = ev_doorbell_send(param.doorbell);
+
+	if (copy_to_user(&p->ret, &param.ret, sizeof(__u32)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static long ioctl_dtprop(struct fsl_hv_ioctl_prop __user *p, int set)
+{
+	struct fsl_hv_ioctl_prop param;
+	char __user *upath, *upropname;
+	void __user *upropval;
+	char *path, *propname;
+	void *propval;
+	int ret = 0;
+
+	/* Get the parameters from the user. */
+	if (copy_from_user(&param, p, sizeof(struct fsl_hv_ioctl_prop)))
+		return -EFAULT;
+
+	upath = (char __user *)(uintptr_t)param.path;
+	upropname = (char __user *)(uintptr_t)param.propname;
+	upropval = (void __user *)(uintptr_t)param.propval;
+
+	path = strndup_user(upath, FH_DTPROP_MAX_PATHLEN);
+	if (IS_ERR(path))
+		return PTR_ERR(path);
+
+	propname = strndup_user(upropname, FH_DTPROP_MAX_PATHLEN);
+	if (IS_ERR(propname)) {
+		ret = PTR_ERR(propname);
+		goto err_free_path;
+	}
+
+	if (param.proplen > FH_DTPROP_MAX_PROPLEN) {
+		ret = -EINVAL;
+		goto err_free_propname;
+	}
+
+	propval = kmalloc(param.proplen, GFP_KERNEL);
+	if (!propval) {
+		ret = -ENOMEM;
+		goto err_free_propname;
+	}
+
+	if (set) {
+		if (copy_from_user(propval, upropval, param.proplen)) {
+			ret = -EFAULT;
+			goto err_free_propval;
+		}
+
+		param.ret = fh_partition_set_dtprop(param.handle,
+						    virt_to_phys(path),
+						    virt_to_phys(propname),
+						    virt_to_phys(propval),
+						    param.proplen);
+	} else {
+		param.ret = fh_partition_get_dtprop(param.handle,
+						    virt_to_phys(path),
+						    virt_to_phys(propname),
+						    virt_to_phys(propval),
+						    &param.proplen);
+
+		if (param.ret == 0) {
+			if (copy_to_user(upropval, propval, param.proplen) ||
+			    put_user(param.proplen, &p->proplen)) {
+				ret = -EFAULT;
+				goto err_free_propval;
+			}
+		}
+	}
+
+	if (put_user(param.ret, &p->ret))
+		ret = -EFAULT;
+
+err_free_propval:
+	kfree(propval);
+err_free_propname:
+	kfree(propname);
+err_free_path:
+	kfree(path);
+
+	return ret;
+}
+
+/*
+ * Ioctl main entry point
+ */
+static long fsl_hv_ioctl(struct file *file, unsigned int cmd,
+			 unsigned long argaddr)
+{
+	void __user *arg = (void __user *)argaddr;
+	long ret;
+
+	switch (cmd) {
+	case FSL_HV_IOCTL_PARTITION_RESTART:
+		ret = ioctl_restart(arg);
+		break;
+	case FSL_HV_IOCTL_PARTITION_GET_STATUS:
+		ret = ioctl_status(arg);
+		break;
+	case FSL_HV_IOCTL_PARTITION_START:
+		ret = ioctl_start(arg);
+		break;
+	case FSL_HV_IOCTL_PARTITION_STOP:
+		ret = ioctl_stop(arg);
+		break;
+	case FSL_HV_IOCTL_MEMCPY:
+		ret = ioctl_memcpy(arg);
+		break;
+	case FSL_HV_IOCTL_DOORBELL:
+		ret = ioctl_doorbell(arg);
+		break;
+	case FSL_HV_IOCTL_GETPROP:
+		ret = ioctl_dtprop(arg, 0);
+		break;
+	case FSL_HV_IOCTL_SETPROP:
+		ret = ioctl_dtprop(arg, 1);
+		break;
+	default:
+		pr_debug("fsl-hv: bad ioctl dir=%u type=%u cmd=%u size=%u\n",
+			 _IOC_DIR(cmd), _IOC_TYPE(cmd), _IOC_NR(cmd),
+			 _IOC_SIZE(cmd));
+		return -ENOTTY;
+	}
+
+	return ret;
+}
+
+/* Linked list of processes that have us open */
+static struct list_head db_list;
+
+/* spinlock for db_list */
+static DEFINE_SPINLOCK(db_list_lock);
+
+/* The size of the doorbell event queue.  This must be a power of two. */
+#define QSIZE	16
+
+/* Returns the next head/tail pointer, wrapping around the queue if necessary */
+#define nextp(x) (((x) + 1) & (QSIZE - 1))
+
+/* Per-open data structure */
+struct doorbell_queue {
+	struct list_head list;
+	spinlock_t lock;
+	wait_queue_head_t wait;
+	unsigned int head;
+	unsigned int tail;
+	uint32_t q[QSIZE];
+};
+
+/* Linked list of ISRs that we registered */
+struct list_head isr_list;
+
+/* Per-ISR data structure */
+struct doorbell_isr {
+	struct list_head list;
+	unsigned int irq;
+	uint32_t doorbell;	/* The doorbell handle */
+	uint32_t partition;	/* The partition handle, if used */
+};
+
+/*
+ * Add a doorbell to all of the doorbell queues
+ */
+static void fsl_hv_queue_doorbell(uint32_t doorbell)
+{
+	struct doorbell_queue *dbq;
+	unsigned long flags;
+
+	/* Prevent another core from modifying db_list */
+	spin_lock_irqsave(&db_list_lock, flags);
+
+	list_for_each_entry(dbq, &db_list, list) {
+		if (dbq->head != nextp(dbq->tail)) {
+			dbq->q[dbq->tail] = doorbell;
+			/*
+			 * This memory barrier eliminates the need to grab
+			 * the spinlock for dbq.
+			 */
+			smp_wmb();
+			dbq->tail = nextp(dbq->tail);
+			wake_up_interruptible(&dbq->wait);
+		}
+	}
+
+	spin_unlock_irqrestore(&db_list_lock, flags);
+}
+
+/*
+ * Interrupt handler for all doorbells
+ *
+ * We use the same interrupt handler for all doorbells.  Whenever a doorbell
+ * is rung, and we receive an interrupt, we just put the handle for that
+ * doorbell (passed to us as *data) into all of the queues.
+ */
+static irqreturn_t fsl_hv_isr(int irq, void *data)
+{
+	fsl_hv_queue_doorbell((uintptr_t) data);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * State change thread function
+ *
+ * The state change notification arrives in an interrupt, but we can't call
+ * blocking_notifier_call_chain() in an interrupt handler.  We could call
+ * atomic_notifier_call_chain(), but that would require the clients' call-back
+ * function to run in interrupt context.  Since we don't want to impose that
+ * restriction on the clients, we use a threaded IRQ to process the
+ * notification in kernel context.
+ */
+static irqreturn_t fsl_hv_state_change_thread(int irq, void *data)
+{
+	struct doorbell_isr *dbisr = data;
+
+	blocking_notifier_call_chain(&failover_subscribers, dbisr->partition,
+				     NULL);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * Interrupt handler for state-change doorbells
+ */
+static irqreturn_t fsl_hv_state_change_isr(int irq, void *data)
+{
+	unsigned int status;
+	struct doorbell_isr *dbisr = data;
+	int ret;
+
+	/* It's still a doorbell, so add it to all the queues. */
+	fsl_hv_queue_doorbell(dbisr->doorbell);
+
+	/* Determine the new state, and if it's stopped, notify the clients. */
+	ret = fh_partition_get_status(dbisr->partition, &status);
+	if (!ret && (status == FH_PARTITION_STOPPED))
+		return IRQ_WAKE_THREAD;
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * Returns a bitmask indicating whether a read will block
+ */
+static __poll_t fsl_hv_poll(struct file *filp, struct poll_table_struct *p)
+{
+	struct doorbell_queue *dbq = filp->private_data;
+	unsigned long flags;
+	__poll_t mask;
+
+	spin_lock_irqsave(&dbq->lock, flags);
+
+	poll_wait(filp, &dbq->wait, p);
+	mask = (dbq->head == dbq->tail) ? 0 : (EPOLLIN | EPOLLRDNORM);
+
+	spin_unlock_irqrestore(&dbq->lock, flags);
+
+	return mask;
+}
+
+/*
+ * Return the handles for any incoming doorbells
+ *
+ * If there are doorbell handles in the queue for this open instance, then
+ * return them to the caller as an array of 32-bit integers.  Otherwise,
+ * block until there is at least one handle to return.
+ */
+static ssize_t fsl_hv_read(struct file *filp, char __user *buf, size_t len,
+			   loff_t *off)
+{
+	struct doorbell_queue *dbq = filp->private_data;
+	uint32_t __user *p = (uint32_t __user *) buf; /* for put_user() */
+	unsigned long flags;
+	ssize_t count = 0;
+
+	/* Make sure we stop when the user buffer is full. */
+	while (len >= sizeof(uint32_t)) {
+		uint32_t dbell;	/* Local copy of doorbell queue data */
+
+		spin_lock_irqsave(&dbq->lock, flags);
+
+		/*
+		 * If the queue is empty, then either we're done or we need
+		 * to block.  If the application specified O_NONBLOCK, then
+		 * we return the appropriate error code.
+		 */
+		if (dbq->head == dbq->tail) {
+			spin_unlock_irqrestore(&dbq->lock, flags);
+			if (count)
+				break;
+			if (filp->f_flags & O_NONBLOCK)
+				return -EAGAIN;
+			if (wait_event_interruptible(dbq->wait,
+						     dbq->head != dbq->tail))
+				return -ERESTARTSYS;
+			continue;
+		}
+
+		/*
+		 * Even though we have an smp_wmb() in the ISR, the core
+		 * might speculatively execute the "dbell = ..." below while
+		 * it's evaluating the if-statement above.  In that case, the
+		 * value put into dbell could be stale if the core accepts the
+		 * speculation. To prevent that, we need a read memory barrier
+		 * here as well.
+		 */
+		smp_rmb();
+
+		/* Copy the data to a temporary local buffer, because
+		 * we can't call copy_to_user() from inside a spinlock
+		 */
+		dbell = dbq->q[dbq->head];
+		dbq->head = nextp(dbq->head);
+
+		spin_unlock_irqrestore(&dbq->lock, flags);
+
+		if (put_user(dbell, p))
+			return -EFAULT;
+		p++;
+		count += sizeof(uint32_t);
+		len -= sizeof(uint32_t);
+	}
+
+	return count;
+}
+
+/*
+ * Open the driver and prepare for reading doorbells.
+ *
+ * Every time an application opens the driver, we create a doorbell queue
+ * for that file handle.  This queue is used for any incoming doorbells.
+ */
+static int fsl_hv_open(struct inode *inode, struct file *filp)
+{
+	struct doorbell_queue *dbq;
+	unsigned long flags;
+
+	dbq = kzalloc(sizeof(struct doorbell_queue), GFP_KERNEL);
+	if (!dbq) {
+		pr_err("fsl-hv: out of memory\n");
+		return -ENOMEM;
+	}
+
+	spin_lock_init(&dbq->lock);
+	init_waitqueue_head(&dbq->wait);
+
+	spin_lock_irqsave(&db_list_lock, flags);
+	list_add(&dbq->list, &db_list);
+	spin_unlock_irqrestore(&db_list_lock, flags);
+
+	filp->private_data = dbq;
+
+	return 0;
+}
+
+/*
+ * Close the driver
+ */
+static int fsl_hv_close(struct inode *inode, struct file *filp)
+{
+	struct doorbell_queue *dbq = filp->private_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&db_list_lock, flags);
+	list_del(&dbq->list);
+	spin_unlock_irqrestore(&db_list_lock, flags);
+
+	kfree(dbq);
+
+	return 0;
+}
+
+static const struct file_operations fsl_hv_fops = {
+	.owner = THIS_MODULE,
+	.open = fsl_hv_open,
+	.release = fsl_hv_close,
+	.poll = fsl_hv_poll,
+	.read = fsl_hv_read,
+	.unlocked_ioctl = fsl_hv_ioctl,
+	.compat_ioctl = compat_ptr_ioctl,
+};
+
+static struct miscdevice fsl_hv_misc_dev = {
+	MISC_DYNAMIC_MINOR,
+	"fsl-hv",
+	&fsl_hv_fops
+};
+
+static irqreturn_t fsl_hv_shutdown_isr(int irq, void *data)
+{
+	orderly_poweroff(false);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * Returns the handle of the parent of the given node
+ *
+ * The handle is the value of the 'hv-handle' property
+ */
+static int get_parent_handle(struct device_node *np)
+{
+	struct device_node *parent;
+	const uint32_t *prop;
+	uint32_t handle;
+	int len;
+
+	parent = of_get_parent(np);
+	if (!parent)
+		/* It's not really possible for this to fail */
+		return -ENODEV;
+
+	/*
+	 * The proper name for the handle property is "hv-handle", but some
+	 * older versions of the hypervisor used "reg".
+	 */
+	prop = of_get_property(parent, "hv-handle", &len);
+	if (!prop)
+		prop = of_get_property(parent, "reg", &len);
+
+	if (!prop || (len != sizeof(uint32_t))) {
+		/* This can happen only if the node is malformed */
+		of_node_put(parent);
+		return -ENODEV;
+	}
+
+	handle = be32_to_cpup(prop);
+	of_node_put(parent);
+
+	return handle;
+}
+
+/*
+ * Register a callback for failover events
+ *
+ * This function is called by device drivers to register their callback
+ * functions for fail-over events.
+ */
+int fsl_hv_failover_register(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&failover_subscribers, nb);
+}
+EXPORT_SYMBOL(fsl_hv_failover_register);
+
+/*
+ * Unregister a callback for failover events
+ */
+int fsl_hv_failover_unregister(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&failover_subscribers, nb);
+}
+EXPORT_SYMBOL(fsl_hv_failover_unregister);
+
+/*
+ * Return TRUE if we're running under FSL hypervisor
+ *
+ * This function checks to see if we're running under the Freescale
+ * hypervisor, and returns zero if we're not, or non-zero if we are.
+ *
+ * First, it checks if MSR[GS]==1, which means we're running under some
+ * hypervisor.  Then it checks if there is a hypervisor node in the device
+ * tree.  Currently, that means there needs to be a node in the root called
+ * "hypervisor" and which has a property named "fsl,hv-version".
+ */
+static int has_fsl_hypervisor(void)
+{
+	struct device_node *node;
+	int ret;
+
+	node = of_find_node_by_path("/hypervisor");
+	if (!node)
+		return 0;
+
+	ret = of_find_property(node, "fsl,hv-version", NULL) != NULL;
+
+	of_node_put(node);
+
+	return ret;
+}
+
+/*
+ * Freescale hypervisor management driver init
+ *
+ * This function is called when this module is loaded.
+ *
+ * Register ourselves as a miscellaneous driver.  This will register the
+ * fops structure and create the right sysfs entries for udev.
+ */
+static int __init fsl_hypervisor_init(void)
+{
+	struct device_node *np;
+	struct doorbell_isr *dbisr, *n;
+	int ret;
+
+	pr_info("Freescale hypervisor management driver\n");
+
+	if (!has_fsl_hypervisor()) {
+		pr_info("fsl-hv: no hypervisor found\n");
+		return -ENODEV;
+	}
+
+	ret = misc_register(&fsl_hv_misc_dev);
+	if (ret) {
+		pr_err("fsl-hv: cannot register device\n");
+		return ret;
+	}
+
+	INIT_LIST_HEAD(&db_list);
+	INIT_LIST_HEAD(&isr_list);
+
+	for_each_compatible_node(np, NULL, "epapr,hv-receive-doorbell") {
+		unsigned int irq;
+		const uint32_t *handle;
+
+		handle = of_get_property(np, "interrupts", NULL);
+		irq = irq_of_parse_and_map(np, 0);
+		if (!handle || (irq == NO_IRQ)) {
+			pr_err("fsl-hv: no 'interrupts' property in %pOF node\n",
+				np);
+			continue;
+		}
+
+		dbisr = kzalloc(sizeof(*dbisr), GFP_KERNEL);
+		if (!dbisr)
+			goto out_of_memory;
+
+		dbisr->irq = irq;
+		dbisr->doorbell = be32_to_cpup(handle);
+
+		if (of_device_is_compatible(np, "fsl,hv-shutdown-doorbell")) {
+			/* The shutdown doorbell gets its own ISR */
+			ret = request_irq(irq, fsl_hv_shutdown_isr, 0,
+					  np->name, NULL);
+		} else if (of_device_is_compatible(np,
+			"fsl,hv-state-change-doorbell")) {
+			/*
+			 * The state change doorbell triggers a notification if
+			 * the state of the managed partition changes to
+			 * "stopped". We need a separate interrupt handler for
+			 * that, and we also need to know the handle of the
+			 * target partition, not just the handle of the
+			 * doorbell.
+			 */
+			dbisr->partition = ret = get_parent_handle(np);
+			if (ret < 0) {
+				pr_err("fsl-hv: node %pOF has missing or "
+				       "malformed parent\n", np);
+				kfree(dbisr);
+				continue;
+			}
+			ret = request_threaded_irq(irq, fsl_hv_state_change_isr,
+						   fsl_hv_state_change_thread,
+						   0, np->name, dbisr);
+		} else
+			ret = request_irq(irq, fsl_hv_isr, 0, np->name, dbisr);
+
+		if (ret < 0) {
+			pr_err("fsl-hv: could not request irq %u for node %pOF\n",
+			       irq, np);
+			kfree(dbisr);
+			continue;
+		}
+
+		list_add(&dbisr->list, &isr_list);
+
+		pr_info("fsl-hv: registered handler for doorbell %u\n",
+			dbisr->doorbell);
+	}
+
+	return 0;
+
+out_of_memory:
+	list_for_each_entry_safe(dbisr, n, &isr_list, list) {
+		free_irq(dbisr->irq, dbisr);
+		list_del(&dbisr->list);
+		kfree(dbisr);
+	}
+
+	misc_deregister(&fsl_hv_misc_dev);
+
+	return -ENOMEM;
+}
+
+/*
+ * Freescale hypervisor management driver termination
+ *
+ * This function is called when this driver is unloaded.
+ */
+static void __exit fsl_hypervisor_exit(void)
+{
+	struct doorbell_isr *dbisr, *n;
+
+	list_for_each_entry_safe(dbisr, n, &isr_list, list) {
+		free_irq(dbisr->irq, dbisr);
+		list_del(&dbisr->list);
+		kfree(dbisr);
+	}
+
+	misc_deregister(&fsl_hv_misc_dev);
+}
+
+module_init(fsl_hypervisor_init);
+module_exit(fsl_hypervisor_exit);
+
+MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
+MODULE_DESCRIPTION("Freescale hypervisor management driver");
+MODULE_LICENSE("GPL v2");