tee: generic TEE subsystem

Initial patch for generic TEE subsystem.
This subsystem provides:
* Registration/un-registration of TEE drivers.
* Shared memory between normal world and secure world.
* Ioctl interface for interaction with user space.
* Sysfs implementation_id of TEE driver

A TEE (Trusted Execution Environment) driver is a driver that interfaces
with a trusted OS running in some secure environment, for example,
TrustZone on ARM cpus, or a separate secure co-processor etc.

The TEE subsystem can serve a TEE driver for a Global Platform compliant
TEE, but it's not limited to only Global Platform TEEs.

This patch builds on other similar implementations trying to solve
the same problem:
* "optee_linuxdriver" by among others
  Jean-michel DELORME<jean-michel.delorme@st.com> and
  Emmanuel MICHEL <emmanuel.michel@st.com>
* "Generic TrustZone Driver" by Javier González <javier@javigon.com>

Acked-by: Andreas Dannenberg <dannenberg@ti.com>
Tested-by: Jerome Forissier <jerome.forissier@linaro.org> (HiKey)
Tested-by: Volodymyr Babchuk <vlad.babchuk@gmail.com> (RCAR H3)
Tested-by: Scott Branden <scott.branden@broadcom.com>
Reviewed-by: Javier González <javier@javigon.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

drivers/tee/tee_private.h

@@ -0,0 +1,129 @@
+/*
+ * Copyright (c) 2015-2016, Linaro Limited
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+#ifndef TEE_PRIVATE_H
+#define TEE_PRIVATE_H
+
+#include <linux/cdev.h>
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/kref.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+
+struct tee_device;
+
+/**
+ * struct tee_shm - shared memory object
+ * @teedev:	device used to allocate the object
+ * @ctx:	context using the object, if NULL the context is gone
+ * @link	link element
+ * @paddr:	physical address of the shared memory
+ * @kaddr:	virtual address of the shared memory
+ * @size:	size of shared memory
+ * @dmabuf:	dmabuf used to for exporting to user space
+ * @flags:	defined by TEE_SHM_* in tee_drv.h
+ * @id:		unique id of a shared memory object on this device
+ */
+struct tee_shm {
+	struct tee_device *teedev;
+	struct tee_context *ctx;
+	struct list_head link;
+	phys_addr_t paddr;
+	void *kaddr;
+	size_t size;
+	struct dma_buf *dmabuf;
+	u32 flags;
+	int id;
+};
+
+struct tee_shm_pool_mgr;
+
+/**
+ * struct tee_shm_pool_mgr_ops - shared memory pool manager operations
+ * @alloc:	called when allocating shared memory
+ * @free:	called when freeing shared memory
+ */
+struct tee_shm_pool_mgr_ops {
+	int (*alloc)(struct tee_shm_pool_mgr *poolmgr, struct tee_shm *shm,
+		     size_t size);
+	void (*free)(struct tee_shm_pool_mgr *poolmgr, struct tee_shm *shm);
+};
+
+/**
+ * struct tee_shm_pool_mgr - shared memory manager
+ * @ops:		operations
+ * @private_data:	private data for the shared memory manager
+ */
+struct tee_shm_pool_mgr {
+	const struct tee_shm_pool_mgr_ops *ops;
+	void *private_data;
+};
+
+/**
+ * struct tee_shm_pool - shared memory pool
+ * @private_mgr:	pool manager for shared memory only between kernel
+ *			and secure world
+ * @dma_buf_mgr:	pool manager for shared memory exported to user space
+ * @destroy:		called when destroying the pool
+ * @private_data:	private data for the pool
+ */
+struct tee_shm_pool {
+	struct tee_shm_pool_mgr private_mgr;
+	struct tee_shm_pool_mgr dma_buf_mgr;
+	void (*destroy)(struct tee_shm_pool *pool);
+	void *private_data;
+};
+
+#define TEE_DEVICE_FLAG_REGISTERED	0x1
+#define TEE_MAX_DEV_NAME_LEN		32
+
+/**
+ * struct tee_device - TEE Device representation
+ * @name:	name of device
+ * @desc:	description of device
+ * @id:		unique id of device
+ * @flags:	represented by TEE_DEVICE_FLAG_REGISTERED above
+ * @dev:	embedded basic device structure
+ * @cdev:	embedded cdev
+ * @num_users:	number of active users of this device
+ * @c_no_user:	completion used when unregistering the device
+ * @mutex:	mutex protecting @num_users and @idr
+ * @idr:	register of shared memory object allocated on this device
+ * @pool:	shared memory pool
+ */
+struct tee_device {
+	char name[TEE_MAX_DEV_NAME_LEN];
+	const struct tee_desc *desc;
+	int id;
+	unsigned int flags;
+
+	struct device dev;
+	struct cdev cdev;
+
+	size_t num_users;
+	struct completion c_no_users;
+	struct mutex mutex;	/* protects num_users and idr */
+
+	struct idr idr;
+	struct tee_shm_pool *pool;
+};
+
+int tee_shm_init(void);
+
+int tee_shm_get_fd(struct tee_shm *shm);
+
+bool tee_device_get(struct tee_device *teedev);
+void tee_device_put(struct tee_device *teedev);
+
+#endif /*TEE_PRIVATE_H*/