[EARLY RFC][PATCH 2/4] ion: Initial hack to create per heap devices

[John Stultz via dri-devel <dri-devel@lists.freedesktop.org>]

One of the issues w/ the /dev/ion interface is that we have to
provide the complexity of a heap query interface and we end up
multiplexing all the heap access through that one interface via
a bit mask (which currently limits the heaps to 32).

There has been a long running todo to provide per-heap devices
which would make the heap discovery/query interface "ls", and
would allow for different heaps to have different permisisons
and sepolicy rules.

TODOs:
* Android doesn't use udev so "ion_heaps/%s" names don't
  automatically create a /dev/ subdir. I need to rework
  from miscdev to creating a proper device class and add
  a "subsystem" entry for the DeviceHandler to match with

* Each CMA region is exposed via a separate heap, not sure
  if this is desired or not, and we may need to improve the
  naming.

Cc: Laura Abbott <labbott@redhat.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Liam Mark <lmark@codeaurora.org>
Cc: Brian Starkey <Brian.Starkey@arm.com>
Cc: Andrew F. Davis <afd@ti.com>
Cc: Alistair Strachan <astrachan@google.com>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
 drivers/staging/android/ion/ion-ioctl.c | 62 +++++++++++++++++++++++++++++++++
 drivers/staging/android/ion/ion.c       | 18 ++++++++++
 drivers/staging/android/ion/ion.h       |  2 ++
 drivers/staging/android/uapi/ion.h      | 28 +++++++++++++++
 4 files changed, 110 insertions(+)

diff --git a/drivers/staging/android/ion/ion-ioctl.c b/drivers/staging/android/ion/ion-ioctl.c
index 458a9f2..ea8d263 100644
--- a/drivers/staging/android/ion/ion-ioctl.c
+++ b/drivers/staging/android/ion/ion-ioctl.c
@@ -12,6 +12,7 @@
 
 union ion_ioctl_arg {
 	struct ion_allocation_data allocation;
+	struct ion_heap_allocation_data heap_allocation;
 	struct ion_heap_query query;
 	u32 version;
 };
@@ -100,3 +101,64 @@ long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	}
 	return ret;
 }
+
+long ion_heap_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	int ret = 0;
+	unsigned int dir;
+	union ion_ioctl_arg data;
+
+	dir = ion_ioctl_dir(cmd);
+
+	if (_IOC_SIZE(cmd) > sizeof(data))
+		return -EINVAL;
+
+	/*
+	 * The copy_from_user is unconditional here for both read and write
+	 * to do the validate. If there is no write for the ioctl, the
+	 * buffer is cleared
+	 */
+	if (copy_from_user(&data, (void __user *)arg, _IOC_SIZE(cmd)))
+		return -EFAULT;
+
+	ret = validate_ioctl_arg(cmd, &data);
+	if (ret) {
+		pr_warn_once("%s: ioctl validate failed\n", __func__);
+		return ret;
+	}
+
+	if (!(dir & _IOC_WRITE))
+		memset(&data, 0, sizeof(data));
+
+	switch (cmd) {
+	case ION_IOC_HEAP_ALLOC:
+	{
+		struct miscdevice *miscdev = filp->private_data;
+		struct ion_heap *heap;
+		int fd;
+
+		heap = container_of(miscdev, struct ion_heap, heap_dev);
+
+		fd = ion_alloc(data.heap_allocation.len,
+			       (1 << heap->id),
+			       data.heap_allocation.flags);
+		if (fd < 0)
+			return fd;
+
+		data.heap_allocation.fd = fd;
+
+		break;
+	}
+	case ION_IOC_VERSION:
+		data.version = ION_VERSION;
+		break;
+	default:
+		return -ENOTTY;
+	}
+
+	if (dir & _IOC_READ) {
+		if (copy_to_user((void __user *)arg, &data, _IOC_SIZE(cmd)))
+			return -EFAULT;
+	}
+	return ret;
+}
diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 6f5afab..1f7c893 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -492,6 +492,14 @@ int ion_query_heaps(struct ion_heap_query *query)
 	return ret;
 }
 
+static const struct file_operations ion_heap_fops = {
+	.owner          = THIS_MODULE,
+	.unlocked_ioctl = ion_heap_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= ion_heap_ioctl,
+#endif
+};
+
 static const struct file_operations ion_fops = {
 	.owner          = THIS_MODULE,
 	.unlocked_ioctl = ion_ioctl,
@@ -540,12 +548,22 @@ void ion_device_add_heap(struct ion_heap *heap)
 	struct ion_device *dev = internal_dev;
 	int ret;
 	struct dentry *heap_root;
+	char *heap_name;
 	char debug_name[64];
 
 	if (!heap->ops->allocate || !heap->ops->free)
 		pr_err("%s: can not add heap with invalid ops struct.\n",
 		       __func__);
 
+	heap_name = kasprintf(GFP_KERNEL, "ion_heaps/%s", heap->name);
+	heap->heap_dev.name = heap_name;
+	heap->heap_dev.minor = MISC_DYNAMIC_MINOR;
+	heap->heap_dev.fops = &ion_heap_fops;
+	heap->heap_dev.parent = NULL;
+	ret = misc_register(&heap->heap_dev);
+	if (ret)
+		pr_err("ion: failed to register misc device.\n");
+
 	spin_lock_init(&heap->free_lock);
 	spin_lock_init(&heap->stat_lock);
 	heap->free_list_size = 0;
diff --git a/drivers/staging/android/ion/ion.h b/drivers/staging/android/ion/ion.h
index 439e682..7ed4a6a 100644
--- a/drivers/staging/android/ion/ion.h
+++ b/drivers/staging/android/ion/ion.h
@@ -170,6 +170,7 @@ struct ion_heap_ops {
  */
 struct ion_heap {
 	struct plist_node node;
+	struct miscdevice heap_dev;
 	struct ion_device *dev;
 	enum ion_heap_type type;
 	struct ion_heap_ops *ops;
@@ -333,6 +334,7 @@ int ion_page_pool_shrink(struct ion_page_pool *pool, gfp_t gfp_mask,
 			 int nr_to_scan);
 
 long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
+long ion_heap_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
 
 int ion_query_heaps(struct ion_heap_query *query);
 
diff --git a/drivers/staging/android/uapi/ion.h b/drivers/staging/android/uapi/ion.h
index c480448..20db09f 100644
--- a/drivers/staging/android/uapi/ion.h
+++ b/drivers/staging/android/uapi/ion.h
@@ -57,6 +57,25 @@ enum ion_heap_type {
  */
 
 /**
+ * struct ion_heap_allocation_data - metadata passed from userspace for
+ *                                   allocations
+ * @len:		size of the allocation
+ * @heap_id_mask:	mask of heap ids to allocate from
+ * @flags:		flags passed to heap
+ * @handle:		pointer that will be populated with a cookie to use to
+ *			refer to this allocation
+ *
+ * Provided by userspace as an argument to the ioctl
+ */
+struct ion_heap_allocation_data {
+	__u64 len;
+	__u32 flags;
+	__u32 fd;
+	__u32 reserved0;
+	__u32 reserved1;
+};
+
+/**
  * struct ion_allocation_data - metadata passed from userspace for allocations
  * @len:		size of the allocation
  * @heap_id_mask:	mask of heap ids to allocate from
@@ -131,4 +150,13 @@ struct ion_heap_query {
  */
 #define ION_IOC_VERSION		_IOR(ION_IOC_MAGIC, 9, u32)
 
+/**
+ * DOC: ION_IOC_HEAP_ALLOC - allocate memory from heap
+ *
+ * Takes an ion_heap_allocation_data struct and returns it with the handle field
+ * populated with the opaque handle for the allocation.
+ */
+#define ION_IOC_HEAP_ALLOC	_IOWR(ION_IOC_MAGIC, 10, \
+				      struct ion_heap_allocation_data)
+
 #endif /* _UAPI_LINUX_ION_H */
-- 
2.7.4

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