tee: implement protected DMA-heap

Implement DMA heap for protected DMA-buf allocation in the TEE
subsystem.

Protected memory refers to memory buffers behind a hardware enforced
firewall. It is not accessible to the kernel during normal circumstances
but rather only accessible to certain hardware IPs or CPUs executing in
higher or differently privileged mode than the kernel itself. This
interface allows to allocate and manage such protected memory buffers
via interaction with a TEE implementation.

The protected memory is allocated for a specific use-case, like Secure
Video Playback, Trusted UI, or Secure Video Recording where certain
hardware devices can access the memory.

The DMA-heaps are enabled explicitly by the TEE backend driver. The TEE
backend drivers needs to implement protected memory pool to manage the
protected memory.

Reviewed-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

1 files changed, 53 insertions, 0 deletions

diff --git a/include/linux/tee_core.h b/include/linux/tee_core.h
index a38494d6b5f4..28b65010b9ed 100644
--- a/include/linux/tee_core.h
+++ b/include/linux/tee_core.h
@@ -8,9 +8,11 @@
 
 #include <linux/cdev.h>
 #include <linux/device.h>
+#include <linux/dma-buf.h>
 #include <linux/idr.h>
 #include <linux/kref.h>
 #include <linux/list.h>
+#include <linux/scatterlist.h>
 #include <linux/tee.h>
 #include <linux/tee_drv.h>
 #include <linux/types.h>
@@ -30,6 +32,12 @@
 #define TEE_DEVICE_FLAG_REGISTERED	0x1
 #define TEE_MAX_DEV_NAME_LEN		32
 
+enum tee_dma_heap_id {
+	TEE_DMA_HEAP_SECURE_VIDEO_PLAY = 1,
+	TEE_DMA_HEAP_TRUSTED_UI,
+	TEE_DMA_HEAP_SECURE_VIDEO_RECORD,
+};
+
 /**
  * struct tee_device - TEE Device representation
  * @name:	name of device
@@ -117,6 +125,36 @@ struct tee_desc {
 };
 
 /**
+ * struct tee_protmem_pool - protected memory pool
+ * @ops:		operations
+ *
+ * This is an abstract interface where this struct is expected to be
+ * embedded in another struct specific to the implementation.
+ */
+struct tee_protmem_pool {
+	const struct tee_protmem_pool_ops *ops;
+};
+
+/**
+ * struct tee_protmem_pool_ops - protected memory pool operations
+ * @alloc:		called when allocating protected memory
+ * @free:		called when freeing protected memory
+ * @update_shm:		called when registering a dma-buf to update the @shm
+ *			with physical address of the buffer or to return the
+ *			@parent_shm of the memory pool
+ * @destroy_pool:	called when destroying the pool
+ */
+struct tee_protmem_pool_ops {
+	int (*alloc)(struct tee_protmem_pool *pool, struct sg_table *sgt,
+		     size_t size, size_t *offs);
+	void (*free)(struct tee_protmem_pool *pool, struct sg_table *sgt);
+	int (*update_shm)(struct tee_protmem_pool *pool, struct sg_table *sgt,
+			  size_t offs, struct tee_shm *shm,
+			  struct tee_shm **parent_shm);
+	void (*destroy_pool)(struct tee_protmem_pool *pool);
+};
+
+/**
  * tee_device_alloc() - Allocate a new struct tee_device instance
  * @teedesc:	Descriptor for this driver
  * @dev:	Parent device for this device
@@ -154,6 +192,11 @@ int tee_device_register(struct tee_device *teedev);
  */
 void tee_device_unregister(struct tee_device *teedev);
 
+int tee_device_register_dma_heap(struct tee_device *teedev,
+				 enum tee_dma_heap_id id,
+				 struct tee_protmem_pool *pool);
+void tee_device_put_all_dma_heaps(struct tee_device *teedev);
+
 /**
  * tee_device_set_dev_groups() - Set device attribute groups
  * @teedev:	Device to register
@@ -230,6 +273,16 @@ static inline void tee_shm_pool_free(struct tee_shm_pool *pool)
 }
 
 /**
+ * tee_protmem_static_pool_alloc() - Create a protected memory manager
+ * @paddr:	Physical address of start of pool
+ * @size:	Size in bytes of the pool
+ *
+ * @returns pointer to a 'struct tee_protmem_pool' or an ERR_PTR on failure.
+ */
+struct tee_protmem_pool *tee_protmem_static_pool_alloc(phys_addr_t paddr,
+						       size_t size);
+
+/**
  * tee_get_drvdata() - Return driver_data pointer
  * @returns the driver_data pointer supplied to tee_register().
  */