platform/goldfish/goldfish_sync.c

// SPDX-License-Identifier: GPL-2.0+

/* The Goldfish sync driver is designed to provide a interface
 * between the underlying host's sync device and the kernel's
 * fence sync framework.
 *
 * The purpose of the device/driver is to enable lightweight creation and
 * signaling of timelines and fences in order to synchronize the guest with
 * host-side graphics events.
 *
 * Each time the interrupt trips, the driver may perform a sync operation.
 */

#include <linux/acpi.h>
#include <linux/dma-fence.h>
#include <linux/fdtable.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/miscdevice.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/sync_file.h>
#include <linux/syscalls.h>
#include <linux/types.h>
#include <linux/uaccess.h>

#include <uapi/linux/goldfish/goldfish_sync.h>

struct sync_pt {
	struct dma_fence base;	/* must be the first field in this struct */
	struct list_head active_list;	/* see active_list_head below */
};

struct goldfish_sync_state;

struct goldfish_sync_timeline {
	struct goldfish_sync_state *sync_state;

	/* This object is owned by userspace from open() calls and also each
	 * sync_pt refers to it.
	 */
	struct kref		kref;
	char			name[32];	/* for debugging */

	u64			context;
	unsigned int		seqno;
	/* list of active (unsignaled/errored) sync_pts */
	struct list_head	active_list_head;
	spinlock_t		lock;	/* protects the fields above */
};

/* The above definitions (command codes, register layout, ioctl definitions)
 * need to be in sync with the following files:
 *
 * Host-side (emulator):
 * external/qemu/android/emulation/goldfish_sync.h
 * external/qemu-android/hw/misc/goldfish_sync.c
 *
 * Guest-side (system image):
 * device/generic/goldfish-opengl/system/egl/goldfish_sync.h
 * device/generic/goldfish/ueventd.ranchu.rc
 * platform/build/target/board/generic/sepolicy/file_contexts
 */
struct goldfish_sync_hostcmd {
	/* sorted for alignment */
	u64 handle;
	u64 hostcmd_handle;
	u32 cmd;
	u32 time_arg;
};

struct goldfish_sync_guestcmd {
	u64 host_command; /* u64 for alignment */
	u64 glsync_handle;
	u64 thread_handle;
	u64 guest_timeline_handle;
};

/* The host operations are: */
enum cmd_id {
	/* Ready signal - used to mark when irq should lower */
	CMD_SYNC_READY			= 0,

	/* Create a new timeline. writes timeline handle */
	CMD_CREATE_SYNC_TIMELINE	= 1,

	/* Create a fence object. reads timeline handle and time argument.
	 * Writes fence fd to the SYNC_REG_HANDLE register.
	 */
	CMD_CREATE_SYNC_FENCE		= 2,

	/* Increments timeline. reads timeline handle and time argument */
	CMD_SYNC_TIMELINE_INC		= 3,

	/* Destroys a timeline. reads timeline handle */
	CMD_DESTROY_SYNC_TIMELINE	= 4,

	/* Starts a wait on the host with the given glsync object and
	 * sync thread handle.
	 */
	CMD_TRIGGER_HOST_WAIT		= 5,
};

/* The host register layout is: */
enum sync_reg_id {
	/* host->guest batch commands */
	SYNC_REG_BATCH_COMMAND			= 0x00,

	/* guest->host batch commands */
	SYNC_REG_BATCH_GUESTCOMMAND		= 0x04,

	/* communicate physical address of host->guest batch commands */
	SYNC_REG_BATCH_COMMAND_ADDR		= 0x08,
	SYNC_REG_BATCH_COMMAND_ADDR_HIGH	= 0x0C, /* 64-bit part */

	/* communicate physical address of guest->host commands */
	SYNC_REG_BATCH_GUESTCOMMAND_ADDR	= 0x10,
	SYNC_REG_BATCH_GUESTCOMMAND_ADDR_HIGH	= 0x14, /* 64-bit part */

	/* signals that the device has been probed */
	SYNC_REG_INIT				= 0x18,
};

#define GOLDFISH_SYNC_MAX_CMDS 256
#define GOLDFISH_SYNC_MAX_CMDS_STACK 32

/* The driver state: */
struct goldfish_sync_state {
	struct miscdevice miscdev;

	char __iomem *reg_base;
	int irq;

	/* Used to generate unique names, see goldfish_sync_timeline::name. */
	u64 id_counter;

	/* |mutex_lock| protects all concurrent access
	 * to timelines for both kernel and user space.
	 */
	struct mutex mutex_lock;

	/* Buffer holding commands issued from host. */
	struct goldfish_sync_hostcmd to_do[GOLDFISH_SYNC_MAX_CMDS];
	u16 to_do_begin;
	u16 to_do_end;
	/* Protects the to_do fields */
	spinlock_t to_do_lock;

	/* Buffers for the reading or writing
	 * of individual commands. The host can directly write
	 * to |batch_hostcmd| (and then this driver immediately
	 * copies contents to |to_do|). This driver either replies
	 * through |batch_hostcmd| or simply issues a
	 * guest->host command through |batch_guestcmd|.
	 */
	struct goldfish_sync_hostcmd batch_hostcmd;
	struct goldfish_sync_guestcmd batch_guestcmd;

	/* Used to give this struct itself to a work queue
	 * function for executing actual sync commands.
	 */
	struct work_struct work_item;
};

static struct goldfish_sync_timeline
*goldfish_dma_fence_parent(struct dma_fence *fence)
{
	return container_of(fence->lock, struct goldfish_sync_timeline, lock);
}

static struct sync_pt *goldfish_sync_fence_to_sync_pt(struct dma_fence *fence)
{
	return container_of(fence, struct sync_pt, base);
}

/* sync_state->mutex_lock must be locked. */
struct goldfish_sync_timeline __must_check
*goldfish_sync_timeline_create(struct goldfish_sync_state *sync_state)
{
	struct goldfish_sync_timeline *tl;

	tl = kzalloc(sizeof(*tl), GFP_KERNEL);
	if (!tl)
		return NULL;

	tl->sync_state = sync_state;
	kref_init(&tl->kref);
	snprintf(tl->name, sizeof(tl->name),
		 "%s:%llu", GOLDFISH_SYNC_DEVICE_NAME,
		 ++sync_state->id_counter);
	tl->context = dma_fence_context_alloc(1);
	tl->seqno = 0;
	INIT_LIST_HEAD(&tl->active_list_head);
	spin_lock_init(&tl->lock);

	return tl;
}

static void goldfish_sync_timeline_free(struct kref *kref)
{
	struct goldfish_sync_timeline *tl =
		container_of(kref, struct goldfish_sync_timeline, kref);

	kfree(tl);
}

static void goldfish_sync_timeline_get(struct goldfish_sync_timeline *tl)
{
	kref_get(&tl->kref);
}

void goldfish_sync_timeline_put(struct goldfish_sync_timeline *tl)
{
	kref_put(&tl->kref, goldfish_sync_timeline_free);
}

void goldfish_sync_timeline_signal(struct goldfish_sync_timeline *tl,
				   unsigned int inc)
{
	unsigned long flags;
	struct sync_pt *pt, *next;

	spin_lock_irqsave(&tl->lock, flags);
	tl->seqno += inc;

	list_for_each_entry_safe(pt, next, &tl->active_list_head, active_list) {
		/* dma_fence_is_signaled_locked has side effects */
		if (dma_fence_is_signaled_locked(&pt->base))
			list_del_init(&pt->active_list);
	}
	spin_unlock_irqrestore(&tl->lock, flags);
}

static const struct dma_fence_ops goldfish_sync_timeline_fence_ops;

static struct sync_pt __must_check
*goldfish_sync_pt_create(struct goldfish_sync_timeline *tl,
			 unsigned int value)
{
	struct sync_pt *pt = kzalloc(sizeof(*pt), GFP_KERNEL);

	if (!pt)
		return NULL;

	dma_fence_init(&pt->base,
		       &goldfish_sync_timeline_fence_ops,
		       &tl->lock,
		       tl->context,
		       value);
	INIT_LIST_HEAD(&pt->active_list);
	goldfish_sync_timeline_get(tl);	/* pt refers to tl */

	return pt;
}

static void goldfish_sync_pt_destroy(struct sync_pt *pt)
{
	struct goldfish_sync_timeline *tl =
		goldfish_dma_fence_parent(&pt->base);
	unsigned long flags;

	spin_lock_irqsave(&tl->lock, flags);
	if (!list_empty(&pt->active_list))
		list_del(&pt->active_list);
	spin_unlock_irqrestore(&tl->lock, flags);

	goldfish_sync_timeline_put(tl);	/* unref pt from tl */
	dma_fence_free(&pt->base);
}

static const char
*goldfish_sync_timeline_fence_get_driver_name(struct dma_fence *fence)
{
	return "sw_sync";
}

static const char
*goldfish_sync_timeline_fence_get_timeline_name(struct dma_fence *fence)
{
	struct goldfish_sync_timeline *tl = goldfish_dma_fence_parent(fence);

	return tl->name;
}

static void goldfish_sync_timeline_fence_release(struct dma_fence *fence)
{
	goldfish_sync_pt_destroy(goldfish_sync_fence_to_sync_pt(fence));
}

static bool goldfish_sync_timeline_fence_signaled(struct dma_fence *fence)
{
	struct goldfish_sync_timeline *tl = goldfish_dma_fence_parent(fence);

	return tl->seqno >= fence->seqno;
}

static bool
goldfish_sync_timeline_fence_enable_signaling(struct dma_fence *fence)
{
	struct sync_pt *pt;
	struct goldfish_sync_timeline *tl;

	if (goldfish_sync_timeline_fence_signaled(fence))
		return false;

	pt = goldfish_sync_fence_to_sync_pt(fence);
	tl = goldfish_dma_fence_parent(fence);
	list_add_tail(&pt->active_list, &tl->active_list_head);
	return true;
}

static void goldfish_sync_timeline_fence_value_str(struct dma_fence *fence,
						   char *str, int size)
{
	snprintf(str, size, "%d", fence->seqno);
}

static void goldfish_sync_timeline_fence_timeline_value_str(
				struct dma_fence *fence,
				char *str, int size)
{
	struct goldfish_sync_timeline *tl = goldfish_dma_fence_parent(fence);

	snprintf(str, size, "%d", tl->seqno);
}

static const struct dma_fence_ops goldfish_sync_timeline_fence_ops = {
	.get_driver_name = goldfish_sync_timeline_fence_get_driver_name,
	.get_timeline_name = goldfish_sync_timeline_fence_get_timeline_name,
	.enable_signaling = goldfish_sync_timeline_fence_enable_signaling,
	.signaled = goldfish_sync_timeline_fence_signaled,
	.wait = dma_fence_default_wait,
	.release = goldfish_sync_timeline_fence_release,
	.fence_value_str = goldfish_sync_timeline_fence_value_str,
	.timeline_value_str = goldfish_sync_timeline_fence_timeline_value_str,
};

struct fence_data {
	struct sync_pt *pt;
	struct sync_file *sync_file_obj;
	int fd;
};

static int __must_check
goldfish_sync_fence_create(struct goldfish_sync_timeline *tl, u32 val,
			   struct fence_data *fence)
{
	struct sync_pt *pt;
	struct sync_file *sync_file_obj = NULL;
	int fd;

	pt = goldfish_sync_pt_create(tl, val);
	if (!pt)
		return -1;

	fd = get_unused_fd_flags(O_CLOEXEC);
	if (fd < 0)
		goto err_cleanup_pt;

	sync_file_obj = sync_file_create(&pt->base);
	if (!sync_file_obj)
		goto err_cleanup_fd_pt;

	fd_install(fd, sync_file_obj->file);

	dma_fence_put(&pt->base);	/* sync_file_obj now owns the fence */

	fence->pt = pt;
	fence->sync_file_obj = sync_file_obj;
	fence->fd = fd;

	return 0;

err_cleanup_fd_pt:
	put_unused_fd(fd);
err_cleanup_pt:
	goldfish_sync_pt_destroy(pt);

	return -1;
}

static void goldfish_sync_fence_destroy(const struct fence_data *fence)
{
	fput(fence->sync_file_obj->file);
	goldfish_sync_pt_destroy(fence->pt);
}

static inline bool
goldfish_sync_cmd_queue(struct goldfish_sync_state *sync_state,
			u32 cmd,
			u64 handle,
			u32 time_arg,
			u64 hostcmd_handle)
{
	unsigned int to_do_end = sync_state->to_do_end;
	struct goldfish_sync_hostcmd *to_do = sync_state->to_do;
	struct goldfish_sync_hostcmd *to_add;

	if (to_do_end >= GOLDFISH_SYNC_MAX_CMDS) {
		const unsigned int to_do_begin = sync_state->to_do_begin;
		const unsigned int to_do_size = to_do_end - to_do_begin;

		/*
		 * this memmove should not run often if
		 * goldfish_sync_work_item_fn grabs commands faster than they
		 * arrive.
		 */
		memmove(&to_do[0], &to_do[to_do_begin],
			sizeof(*to_do) * to_do_size);
		to_do_end = to_do_size;
		sync_state->to_do_begin = 0;

		if (to_do_end >= GOLDFISH_SYNC_MAX_CMDS)
			return false;
	}

	to_add = &to_do[to_do_end];

	to_add->cmd = cmd;
	to_add->handle = handle;
	to_add->time_arg = time_arg;
	to_add->hostcmd_handle = hostcmd_handle;

	sync_state->to_do_end = to_do_end + 1;
	return true;
}

static inline void
goldfish_sync_hostcmd_reply(struct goldfish_sync_state *sync_state,
			    u32 cmd,
			    u64 handle,
			    u32 time_arg,
			    u64 hostcmd_handle)
{
	unsigned long irq_flags;
	struct goldfish_sync_hostcmd *batch_hostcmd =
		&sync_state->batch_hostcmd;

	spin_lock_irqsave(&sync_state->to_do_lock, irq_flags);

	batch_hostcmd->cmd = cmd;
	batch_hostcmd->handle = handle;
	batch_hostcmd->time_arg = time_arg;
	batch_hostcmd->hostcmd_handle = hostcmd_handle;
	writel(0, sync_state->reg_base + SYNC_REG_BATCH_COMMAND);

	spin_unlock_irqrestore(&sync_state->to_do_lock, irq_flags);
}

static inline void
goldfish_sync_send_guestcmd(struct goldfish_sync_state *sync_state,
			    u32 cmd,
			    u64 glsync_handle,
			    u64 thread_handle,
			    u64 timeline_handle)
{
	unsigned long irq_flags;
	struct goldfish_sync_guestcmd *batch_guestcmd =
		&sync_state->batch_guestcmd;

	spin_lock_irqsave(&sync_state->to_do_lock, irq_flags);

	batch_guestcmd->host_command = cmd;
	batch_guestcmd->glsync_handle = glsync_handle;
	batch_guestcmd->thread_handle = thread_handle;
	batch_guestcmd->guest_timeline_handle = timeline_handle;
	writel(0, sync_state->reg_base + SYNC_REG_BATCH_GUESTCOMMAND);

	spin_unlock_irqrestore(&sync_state->to_do_lock, irq_flags);
}

/* |goldfish_sync_interrupt| handles IRQ raises from the virtual device.
 * In the context of OpenGL, this interrupt will fire whenever we need
 * to signal a fence fd in the guest, with the command
 * |CMD_SYNC_TIMELINE_INC|.
 * However, because this function will be called in an interrupt context,
 * it is necessary to do the actual work of signaling off of interrupt context.
 * The shared work queue is used for this purpose. At the end when
 * all pending commands are intercepted by the interrupt handler,
 * we call |schedule_work|, which will later run the actual
 * desired sync command in |goldfish_sync_work_item_fn|.
 */
static irqreturn_t
goldfish_sync_interrupt_impl(struct goldfish_sync_state *sync_state)
{
	struct goldfish_sync_hostcmd *batch_hostcmd =
			&sync_state->batch_hostcmd;

	spin_lock(&sync_state->to_do_lock);
	for (;;) {
		u32 nextcmd;
		u32 command_r;
		u64 handle_rw;
		u32 time_r;
		u64 hostcmd_handle_rw;

		readl(sync_state->reg_base + SYNC_REG_BATCH_COMMAND);
		nextcmd = batch_hostcmd->cmd;

		if (nextcmd == 0)
			break;

		command_r = nextcmd;
		handle_rw = batch_hostcmd->handle;
		time_r = batch_hostcmd->time_arg;
		hostcmd_handle_rw = batch_hostcmd->hostcmd_handle;

		BUG_ON(!goldfish_sync_cmd_queue(sync_state,
						command_r,
						handle_rw,
						time_r,
						hostcmd_handle_rw));
	}
	spin_unlock(&sync_state->to_do_lock);

	schedule_work(&sync_state->work_item);
	return IRQ_HANDLED;
}

static const struct file_operations goldfish_sync_fops;

static irqreturn_t goldfish_sync_interrupt(int irq, void *dev_id)
{
	struct goldfish_sync_state *sync_state = dev_id;

	return (sync_state->miscdev.fops == &goldfish_sync_fops) ?
		goldfish_sync_interrupt_impl(sync_state) : IRQ_NONE;
}

/* We expect that commands will come in at a slow enough rate
 * so that incoming items will not be more than
 * GOLDFISH_SYNC_MAX_CMDS.
 *
 * This is because the way the sync device is used,
 * it's only for managing buffer data transfers per frame,
 * with a sequential dependency between putting things in
 * to_do and taking them out. Once a set of commands is
 * queued up in to_do, the user of the device waits for
 * them to be processed before queuing additional commands,
 * which limits the rate at which commands come in
 * to the rate at which we take them out here.
 *
 * We also don't expect more than MAX_CMDS to be issued
 * at once; there is a correspondence between
 * which buffers need swapping to the (display / buffer queue)
 * to particular commands, and we don't expect there to be
 * enough display or buffer queues in operation at once
 * to overrun GOLDFISH_SYNC_MAX_CMDS.
 */
static u32 __must_check
goldfish_sync_grab_commands(struct goldfish_sync_state *sync_state,
			    struct goldfish_sync_hostcmd *dst,
			    const u32 dst_size)
{
	u32 result;
	unsigned int to_do_begin;
	unsigned int to_do_end;
	unsigned int to_do_size;
	struct goldfish_sync_hostcmd *to_do;
	unsigned long irq_flags;

	spin_lock_irqsave(&sync_state->to_do_lock, irq_flags);

	to_do = sync_state->to_do;
	to_do_begin = sync_state->to_do_begin;
	to_do_end = sync_state->to_do_end;
	to_do_size = to_do_end - to_do_begin;

	if (to_do_size > dst_size) {
		memcpy(dst, &to_do[to_do_begin], sizeof(*to_do) * dst_size);
		sync_state->to_do_begin = to_do_begin + dst_size;
		result = dst_size;
	} else {
		memcpy(dst, &to_do[to_do_begin], sizeof(*to_do) * to_do_size);
		sync_state->to_do_begin = 0;
		sync_state->to_do_end = 0;
		result = to_do_size;
	}

	spin_unlock_irqrestore(&sync_state->to_do_lock, irq_flags);

	return result;
}

void goldfish_sync_run_hostcmd(struct goldfish_sync_state *sync_state,
			       struct goldfish_sync_hostcmd *todo)
{
	struct goldfish_sync_timeline *tl =
		(struct goldfish_sync_timeline *)(uintptr_t)todo->handle;
	struct fence_data fence;

	switch (todo->cmd) {
	case CMD_SYNC_READY:
		break;

	case CMD_CREATE_SYNC_TIMELINE:
		tl = goldfish_sync_timeline_create(sync_state);
		WARN_ON(!tl);
		goldfish_sync_hostcmd_reply(sync_state,
					    CMD_CREATE_SYNC_TIMELINE,
					    (uintptr_t)tl,
					    0,
					    todo->hostcmd_handle);
		break;

	case CMD_CREATE_SYNC_FENCE:
		WARN_ON(!tl);
		if (goldfish_sync_fence_create(tl, todo->time_arg, &fence)) {
			fence.fd = -1;
		}
		goldfish_sync_hostcmd_reply(sync_state,
					    CMD_CREATE_SYNC_FENCE,
					    fence.fd,
					    0,
					    todo->hostcmd_handle);
		break;

	case CMD_SYNC_TIMELINE_INC:
		WARN_ON(!tl);
		goldfish_sync_timeline_signal(tl, todo->time_arg);
		break;

	case CMD_DESTROY_SYNC_TIMELINE:
		WARN_ON(!tl);
		goldfish_sync_timeline_put(tl);
		break;
	}
}

/* |goldfish_sync_work_item_fn| does the actual work of servicing
 * host->guest sync commands. This function is triggered whenever
 * the IRQ for the goldfish sync device is raised. Once it starts
 * running, it grabs the contents of the buffer containing the
 * commands it needs to execute (there may be multiple, because
 * our IRQ is active high and not edge triggered), and then
 * runs all of them one after the other.
 */
static void goldfish_sync_work_item_fn(struct work_struct *input)
{
	struct goldfish_sync_state *sync_state =
		container_of(input, struct goldfish_sync_state, work_item);

	struct goldfish_sync_hostcmd to_run[GOLDFISH_SYNC_MAX_CMDS_STACK];

	mutex_lock(&sync_state->mutex_lock);

	while (true) {
		u32 i;
		u32 to_do_end =
			goldfish_sync_grab_commands(sync_state, to_run,
						    ARRAY_SIZE(to_run));

		for (i = 0; i < to_do_end; i++)
			goldfish_sync_run_hostcmd(sync_state, &to_run[i]);

		if (to_do_end < ARRAY_SIZE(to_run))
			break;
	}

	mutex_unlock(&sync_state->mutex_lock);
}

static int goldfish_sync_open(struct inode *inode, struct file *filp)
{
	struct goldfish_sync_state *sync_state =
		container_of(filp->private_data,
			     struct goldfish_sync_state,
			     miscdev);

	if (mutex_lock_interruptible(&sync_state->mutex_lock))
		return -ERESTARTSYS;

	filp->private_data = goldfish_sync_timeline_create(sync_state);
	mutex_unlock(&sync_state->mutex_lock);

	return filp->private_data ? 0 : -ENOMEM;
}

static int goldfish_sync_release(struct inode *inode, struct file *filp)
{
	struct goldfish_sync_timeline *tl = filp->private_data;

	goldfish_sync_timeline_put(tl);
	return 0;
}

/* |goldfish_sync_ioctl| is the guest-facing interface of goldfish sync
 * and is used in conjunction with eglCreateSyncKHR to queue up the
 * actual work of waiting for the EGL sync command to complete,
 * possibly returning a fence fd to the guest.
 */
static long
goldfish_sync_ioctl_locked(struct goldfish_sync_timeline *tl,
			   unsigned int cmd,
			   unsigned long arg)
{
	struct goldfish_sync_ioctl_info ioctl_data;
	struct fence_data fence;

	switch (cmd) {
	case GOLDFISH_SYNC_IOC_QUEUE_WORK:
		if (copy_from_user(&ioctl_data,
				   (void __user *)arg,
				   sizeof(ioctl_data)))
			return -EFAULT;

		if (!ioctl_data.host_syncthread_handle_in)
			return -EFAULT;

		if (goldfish_sync_fence_create(tl, tl->seqno + 1, &fence))
			return -EAGAIN;

		ioctl_data.fence_fd_out = fence.fd;
		if (copy_to_user((void __user *)arg,
				 &ioctl_data,
				 sizeof(ioctl_data))) {
			goldfish_sync_fence_destroy(&fence);
			return -EFAULT;
		}

		/* We are now about to trigger a host-side wait;
		 * accumulate on |pending_waits|.
		 */
		goldfish_sync_send_guestcmd(tl->sync_state,
				CMD_TRIGGER_HOST_WAIT,
				ioctl_data.host_glsync_handle_in,
				ioctl_data.host_syncthread_handle_in,
				(u64)(uintptr_t)tl);
		return 0;

	default:
		return -ENOTTY;
	}
}

static long goldfish_sync_ioctl(struct file *filp,
				unsigned int cmd,
				unsigned long arg)
{
	struct goldfish_sync_timeline *tl = filp->private_data;
	struct goldfish_sync_state *x = tl->sync_state;
	long res;

	if (mutex_lock_interruptible(&x->mutex_lock))
		return -ERESTARTSYS;

	res = goldfish_sync_ioctl_locked(tl, cmd, arg);
	mutex_unlock(&x->mutex_lock);

	return res;
}

static bool setup_verify_batch_cmd_addr(char *reg_base,
					void *batch_addr,
					u32 addr_offset,
					u32 addr_offset_high)
{
	u64 batch_addr_phys;
	u64 batch_addr_phys_test_lo;
	u64 batch_addr_phys_test_hi;

	batch_addr_phys = virt_to_phys(batch_addr);
	writel(lower_32_bits(batch_addr_phys), reg_base + addr_offset);
	writel(upper_32_bits(batch_addr_phys), reg_base + addr_offset_high);

	batch_addr_phys_test_lo = readl(reg_base + addr_offset);
	batch_addr_phys_test_hi = readl(reg_base + addr_offset_high);

	batch_addr_phys = batch_addr_phys_test_lo |
		(batch_addr_phys_test_hi << 32);

	return virt_to_phys(batch_addr) == batch_addr_phys;
}

static const struct file_operations goldfish_sync_fops = {
	.owner = THIS_MODULE,
	.open = goldfish_sync_open,
	.release = goldfish_sync_release,
	.unlocked_ioctl = goldfish_sync_ioctl,
	.compat_ioctl = goldfish_sync_ioctl,
};

static void fill_miscdevice(struct miscdevice *misc)
{
	misc->name = GOLDFISH_SYNC_DEVICE_NAME;
	misc->minor = MISC_DYNAMIC_MINOR;
	misc->fops = &goldfish_sync_fops;
}

static int goldfish_sync_probe(struct platform_device *pdev)
{
	struct goldfish_sync_state *sync_state;
	struct resource *ioresource;
	int result;

	sync_state = devm_kzalloc(&pdev->dev, sizeof(*sync_state), GFP_KERNEL);
	if (!sync_state)
		return -ENOMEM;

	spin_lock_init(&sync_state->to_do_lock);
	mutex_init(&sync_state->mutex_lock);
	INIT_WORK(&sync_state->work_item, goldfish_sync_work_item_fn);

	ioresource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!ioresource)
		return -ENODEV;

	sync_state->reg_base =
		devm_ioremap(&pdev->dev, ioresource->start, PAGE_SIZE);
	if (!sync_state->reg_base)
		return -ENOMEM;

	result = platform_get_irq(pdev, 0);
	if (result < 0)
		return -ENODEV;

	sync_state->irq = result;

	result = devm_request_irq(&pdev->dev,
				  sync_state->irq,
				  goldfish_sync_interrupt,
				  IRQF_SHARED,
				  pdev->name,
				  sync_state);
	if (result)
		return -ENODEV;

	if (!setup_verify_batch_cmd_addr(sync_state->reg_base,
				&sync_state->batch_hostcmd,
				SYNC_REG_BATCH_COMMAND_ADDR,
				SYNC_REG_BATCH_COMMAND_ADDR_HIGH))
		return -ENODEV;

	if (!setup_verify_batch_cmd_addr(sync_state->reg_base,
				&sync_state->batch_guestcmd,
				SYNC_REG_BATCH_GUESTCOMMAND_ADDR,
				SYNC_REG_BATCH_GUESTCOMMAND_ADDR_HIGH))
		return -ENODEV;

	fill_miscdevice(&sync_state->miscdev);
	result = misc_register(&sync_state->miscdev);
	if (result)
		return -ENODEV;

	writel(0, sync_state->reg_base + SYNC_REG_INIT);

	platform_set_drvdata(pdev, sync_state);

	return 0;
}

static int goldfish_sync_remove(struct platform_device *pdev)
{
	struct goldfish_sync_state *sync_state = platform_get_drvdata(pdev);

	misc_deregister(&sync_state->miscdev);
	return 0;
}

static const struct of_device_id goldfish_sync_of_match[] = {
	{ .compatible = "google,goldfish-sync", },
	{},
};
MODULE_DEVICE_TABLE(of, goldfish_sync_of_match);

static const struct acpi_device_id goldfish_sync_acpi_match[] = {
	{ "GFSH0006", 0 },
	{ },
};
MODULE_DEVICE_TABLE(acpi, goldfish_sync_acpi_match);

static struct platform_driver goldfish_sync = {
	.probe = goldfish_sync_probe,
	.remove = goldfish_sync_remove,
	.driver = {
		.name = GOLDFISH_SYNC_DEVICE_NAME,
		.of_match_table = goldfish_sync_of_match,
		.acpi_match_table = ACPI_PTR(goldfish_sync_acpi_match),
	}
};
module_platform_driver(goldfish_sync);

MODULE_AUTHOR("Google, Inc.");
MODULE_DESCRIPTION("Android QEMU Sync Driver");
MODULE_LICENSE("GPL");
MODULE_VERSION("2.0");