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>

1 files changed, 893 insertions, 0 deletions

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
new file mode 100644
index 000000000000..5c60bf4423e6
--- /dev/null
+++ b/drivers/tee/tee_core.c
@@ -0,0 +1,893 @@
+/*
+ * 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.
+ *
+ */
+
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/idr.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/tee_drv.h>
+#include <linux/uaccess.h>
+#include "tee_private.h"
+
+#define TEE_NUM_DEVICES	32
+
+#define TEE_IOCTL_PARAM_SIZE(x) (sizeof(struct tee_param) * (x))
+
+/*
+ * Unprivileged devices in the lower half range and privileged devices in
+ * the upper half range.
+ */
+static DECLARE_BITMAP(dev_mask, TEE_NUM_DEVICES);
+static DEFINE_SPINLOCK(driver_lock);
+
+static struct class *tee_class;
+static dev_t tee_devt;
+
+static int tee_open(struct inode *inode, struct file *filp)
+{
+	int rc;
+	struct tee_device *teedev;
+	struct tee_context *ctx;
+
+	teedev = container_of(inode->i_cdev, struct tee_device, cdev);
+	if (!tee_device_get(teedev))
+		return -EINVAL;
+
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+	if (!ctx) {
+		rc = -ENOMEM;
+		goto err;
+	}
+
+	ctx->teedev = teedev;
+	INIT_LIST_HEAD(&ctx->list_shm);
+	filp->private_data = ctx;
+	rc = teedev->desc->ops->open(ctx);
+	if (rc)
+		goto err;
+
+	return 0;
+err:
+	kfree(ctx);
+	tee_device_put(teedev);
+	return rc;
+}
+
+static int tee_release(struct inode *inode, struct file *filp)
+{
+	struct tee_context *ctx = filp->private_data;
+	struct tee_device *teedev = ctx->teedev;
+	struct tee_shm *shm;
+
+	ctx->teedev->desc->ops->release(ctx);
+	mutex_lock(&ctx->teedev->mutex);
+	list_for_each_entry(shm, &ctx->list_shm, link)
+		shm->ctx = NULL;
+	mutex_unlock(&ctx->teedev->mutex);
+	kfree(ctx);
+	tee_device_put(teedev);
+	return 0;
+}
+
+static int tee_ioctl_version(struct tee_context *ctx,
+			     struct tee_ioctl_version_data __user *uvers)
+{
+	struct tee_ioctl_version_data vers;
+
+	ctx->teedev->desc->ops->get_version(ctx->teedev, &vers);
+	if (copy_to_user(uvers, &vers, sizeof(vers)))
+		return -EFAULT;
+	return 0;
+}
+
+static int tee_ioctl_shm_alloc(struct tee_context *ctx,
+			       struct tee_ioctl_shm_alloc_data __user *udata)
+{
+	long ret;
+	struct tee_ioctl_shm_alloc_data data;
+	struct tee_shm *shm;
+
+	if (copy_from_user(&data, udata, sizeof(data)))
+		return -EFAULT;
+
+	/* Currently no input flags are supported */
+	if (data.flags)
+		return -EINVAL;
+
+	data.id = -1;
+
+	shm = tee_shm_alloc(ctx, data.size, TEE_SHM_MAPPED | TEE_SHM_DMA_BUF);
+	if (IS_ERR(shm))
+		return PTR_ERR(shm);
+
+	data.id = shm->id;
+	data.flags = shm->flags;
+	data.size = shm->size;
+
+	if (copy_to_user(udata, &data, sizeof(data)))
+		ret = -EFAULT;
+	else
+		ret = tee_shm_get_fd(shm);
+
+	/*
+	 * When user space closes the file descriptor the shared memory
+	 * should be freed or if tee_shm_get_fd() failed then it will
+	 * be freed immediately.
+	 */
+	tee_shm_put(shm);
+	return ret;
+}
+
+static int params_from_user(struct tee_context *ctx, struct tee_param *params,
+			    size_t num_params,
+			    struct tee_ioctl_param __user *uparams)
+{
+	size_t n;
+
+	for (n = 0; n < num_params; n++) {
+		struct tee_shm *shm;
+		struct tee_ioctl_param ip;
+
+		if (copy_from_user(&ip, uparams + n, sizeof(ip)))
+			return -EFAULT;
+
+		/* All unused attribute bits has to be zero */
+		if (ip.attr & ~TEE_IOCTL_PARAM_ATTR_TYPE_MASK)
+			return -EINVAL;
+
+		params[n].attr = ip.attr;
+		switch (ip.attr) {
+		case TEE_IOCTL_PARAM_ATTR_TYPE_NONE:
+		case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT:
+			break;
+		case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT:
+		case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT:
+			params[n].u.value.a = ip.a;
+			params[n].u.value.b = ip.b;
+			params[n].u.value.c = ip.c;
+			break;
+		case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT:
+		case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT:
+		case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT:
+			/*
+			 * If we fail to get a pointer to a shared memory
+			 * object (and increase the ref count) from an
+			 * identifier we return an error. All pointers that
+			 * has been added in params have an increased ref
+			 * count. It's the callers responibility to do
+			 * tee_shm_put() on all resolved pointers.
+			 */
+			shm = tee_shm_get_from_id(ctx, ip.c);
+			if (IS_ERR(shm))
+				return PTR_ERR(shm);
+
+			params[n].u.memref.shm_offs = ip.a;
+			params[n].u.memref.size = ip.b;
+			params[n].u.memref.shm = shm;
+			break;
+		default:
+			/* Unknown attribute */
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+
+static int params_to_user(struct tee_ioctl_param __user *uparams,
+			  size_t num_params, struct tee_param *params)
+{
+	size_t n;
+
+	for (n = 0; n < num_params; n++) {
+		struct tee_ioctl_param __user *up = uparams + n;
+		struct tee_param *p = params + n;
+
+		switch (p->attr) {
+		case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT:
+		case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT:
+			if (put_user(p->u.value.a, &up->a) ||
+			    put_user(p->u.value.b, &up->b) ||
+			    put_user(p->u.value.c, &up->c))
+				return -EFAULT;
+			break;
+		case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT:
+		case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT:
+			if (put_user((u64)p->u.memref.size, &up->b))
+				return -EFAULT;
+		default:
+			break;
+		}
+	}
+	return 0;
+}
+
+static bool param_is_memref(struct tee_param *param)
+{
+	switch (param->attr & TEE_IOCTL_PARAM_ATTR_TYPE_MASK) {
+	case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT:
+	case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT:
+	case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static int tee_ioctl_open_session(struct tee_context *ctx,
+				  struct tee_ioctl_buf_data __user *ubuf)
+{
+	int rc;
+	size_t n;
+	struct tee_ioctl_buf_data buf;
+	struct tee_ioctl_open_session_arg __user *uarg;
+	struct tee_ioctl_open_session_arg arg;
+	struct tee_ioctl_param __user *uparams = NULL;
+	struct tee_param *params = NULL;
+	bool have_session = false;
+
+	if (!ctx->teedev->desc->ops->open_session)
+		return -EINVAL;
+
+	if (copy_from_user(&buf, ubuf, sizeof(buf)))
+		return -EFAULT;
+
+	if (buf.buf_len > TEE_MAX_ARG_SIZE ||
+	    buf.buf_len < sizeof(struct tee_ioctl_open_session_arg))
+		return -EINVAL;
+
+	uarg = u64_to_user_ptr(buf.buf_ptr);
+	if (copy_from_user(&arg, uarg, sizeof(arg)))
+		return -EFAULT;
+
+	if (sizeof(arg) + TEE_IOCTL_PARAM_SIZE(arg.num_params) != buf.buf_len)
+		return -EINVAL;
+
+	if (arg.num_params) {
+		params = kcalloc(arg.num_params, sizeof(struct tee_param),
+				 GFP_KERNEL);
+		if (!params)
+			return -ENOMEM;
+		uparams = uarg->params;
+		rc = params_from_user(ctx, params, arg.num_params, uparams);
+		if (rc)
+			goto out;
+	}
+
+	rc = ctx->teedev->desc->ops->open_session(ctx, &arg, params);
+	if (rc)
+		goto out;
+	have_session = true;
+
+	if (put_user(arg.session, &uarg->session) ||
+	    put_user(arg.ret, &uarg->ret) ||
+	    put_user(arg.ret_origin, &uarg->ret_origin)) {
+		rc = -EFAULT;
+		goto out;
+	}
+	rc = params_to_user(uparams, arg.num_params, params);
+out:
+	/*
+	 * If we've succeeded to open the session but failed to communicate
+	 * it back to user space, close the session again to avoid leakage.
+	 */
+	if (rc && have_session && ctx->teedev->desc->ops->close_session)
+		ctx->teedev->desc->ops->close_session(ctx, arg.session);
+
+	if (params) {
+		/* Decrease ref count for all valid shared memory pointers */
+		for (n = 0; n < arg.num_params; n++)
+			if (param_is_memref(params + n) &&
+			    params[n].u.memref.shm)
+				tee_shm_put(params[n].u.memref.shm);
+		kfree(params);
+	}
+
+	return rc;
+}
+
+static int tee_ioctl_invoke(struct tee_context *ctx,
+			    struct tee_ioctl_buf_data __user *ubuf)
+{
+	int rc;
+	size_t n;
+	struct tee_ioctl_buf_data buf;
+	struct tee_ioctl_invoke_arg __user *uarg;
+	struct tee_ioctl_invoke_arg arg;
+	struct tee_ioctl_param __user *uparams = NULL;
+	struct tee_param *params = NULL;
+
+	if (!ctx->teedev->desc->ops->invoke_func)
+		return -EINVAL;
+
+	if (copy_from_user(&buf, ubuf, sizeof(buf)))
+		return -EFAULT;
+
+	if (buf.buf_len > TEE_MAX_ARG_SIZE ||
+	    buf.buf_len < sizeof(struct tee_ioctl_invoke_arg))
+		return -EINVAL;
+
+	uarg = u64_to_user_ptr(buf.buf_ptr);
+	if (copy_from_user(&arg, uarg, sizeof(arg)))
+		return -EFAULT;
+
+	if (sizeof(arg) + TEE_IOCTL_PARAM_SIZE(arg.num_params) != buf.buf_len)
+		return -EINVAL;
+
+	if (arg.num_params) {
+		params = kcalloc(arg.num_params, sizeof(struct tee_param),
+				 GFP_KERNEL);
+		if (!params)
+			return -ENOMEM;
+		uparams = uarg->params;
+		rc = params_from_user(ctx, params, arg.num_params, uparams);
+		if (rc)
+			goto out;
+	}
+
+	rc = ctx->teedev->desc->ops->invoke_func(ctx, &arg, params);
+	if (rc)
+		goto out;
+
+	if (put_user(arg.ret, &uarg->ret) ||
+	    put_user(arg.ret_origin, &uarg->ret_origin)) {
+		rc = -EFAULT;
+		goto out;
+	}
+	rc = params_to_user(uparams, arg.num_params, params);
+out:
+	if (params) {
+		/* Decrease ref count for all valid shared memory pointers */
+		for (n = 0; n < arg.num_params; n++)
+			if (param_is_memref(params + n) &&
+			    params[n].u.memref.shm)
+				tee_shm_put(params[n].u.memref.shm);
+		kfree(params);
+	}
+	return rc;
+}
+
+static int tee_ioctl_cancel(struct tee_context *ctx,
+			    struct tee_ioctl_cancel_arg __user *uarg)
+{
+	struct tee_ioctl_cancel_arg arg;
+
+	if (!ctx->teedev->desc->ops->cancel_req)
+		return -EINVAL;
+
+	if (copy_from_user(&arg, uarg, sizeof(arg)))
+		return -EFAULT;
+
+	return ctx->teedev->desc->ops->cancel_req(ctx, arg.cancel_id,
+						  arg.session);
+}
+
+static int
+tee_ioctl_close_session(struct tee_context *ctx,
+			struct tee_ioctl_close_session_arg __user *uarg)
+{
+	struct tee_ioctl_close_session_arg arg;
+
+	if (!ctx->teedev->desc->ops->close_session)
+		return -EINVAL;
+
+	if (copy_from_user(&arg, uarg, sizeof(arg)))
+		return -EFAULT;
+
+	return ctx->teedev->desc->ops->close_session(ctx, arg.session);
+}
+
+static int params_to_supp(struct tee_context *ctx,
+			  struct tee_ioctl_param __user *uparams,
+			  size_t num_params, struct tee_param *params)
+{
+	size_t n;
+
+	for (n = 0; n < num_params; n++) {
+		struct tee_ioctl_param ip;
+		struct tee_param *p = params + n;
+
+		ip.attr = p->attr & TEE_IOCTL_PARAM_ATTR_TYPE_MASK;
+		switch (p->attr) {
+		case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT:
+		case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT:
+			ip.a = p->u.value.a;
+			ip.b = p->u.value.b;
+			ip.c = p->u.value.c;
+			break;
+		case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT:
+		case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT:
+		case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT:
+			ip.b = p->u.memref.size;
+			if (!p->u.memref.shm) {
+				ip.a = 0;
+				ip.c = (u64)-1; /* invalid shm id */
+				break;
+			}
+			ip.a = p->u.memref.shm_offs;
+			ip.c = p->u.memref.shm->id;
+			break;
+		default:
+			ip.a = 0;
+			ip.b = 0;
+			ip.c = 0;
+			break;
+		}
+
+		if (copy_to_user(uparams + n, &ip, sizeof(ip)))
+			return -EFAULT;
+	}
+
+	return 0;
+}
+
+static int tee_ioctl_supp_recv(struct tee_context *ctx,
+			       struct tee_ioctl_buf_data __user *ubuf)
+{
+	int rc;
+	struct tee_ioctl_buf_data buf;
+	struct tee_iocl_supp_recv_arg __user *uarg;
+	struct tee_param *params;
+	u32 num_params;
+	u32 func;
+
+	if (!ctx->teedev->desc->ops->supp_recv)
+		return -EINVAL;
+
+	if (copy_from_user(&buf, ubuf, sizeof(buf)))
+		return -EFAULT;
+
+	if (buf.buf_len > TEE_MAX_ARG_SIZE ||
+	    buf.buf_len < sizeof(struct tee_iocl_supp_recv_arg))
+		return -EINVAL;
+
+	uarg = u64_to_user_ptr(buf.buf_ptr);
+	if (get_user(num_params, &uarg->num_params))
+		return -EFAULT;
+
+	if (sizeof(*uarg) + TEE_IOCTL_PARAM_SIZE(num_params) != buf.buf_len)
+		return -EINVAL;
+
+	params = kcalloc(num_params, sizeof(struct tee_param), GFP_KERNEL);
+	if (!params)
+		return -ENOMEM;
+
+	rc = ctx->teedev->desc->ops->supp_recv(ctx, &func, &num_params, params);
+	if (rc)
+		goto out;
+
+	if (put_user(func, &uarg->func) ||
+	    put_user(num_params, &uarg->num_params)) {
+		rc = -EFAULT;
+		goto out;
+	}
+
+	rc = params_to_supp(ctx, uarg->params, num_params, params);
+out:
+	kfree(params);
+	return rc;
+}
+
+static int params_from_supp(struct tee_param *params, size_t num_params,
+			    struct tee_ioctl_param __user *uparams)
+{
+	size_t n;
+
+	for (n = 0; n < num_params; n++) {
+		struct tee_param *p = params + n;
+		struct tee_ioctl_param ip;
+
+		if (copy_from_user(&ip, uparams + n, sizeof(ip)))
+			return -EFAULT;
+
+		/* All unused attribute bits has to be zero */
+		if (ip.attr & ~TEE_IOCTL_PARAM_ATTR_TYPE_MASK)
+			return -EINVAL;
+
+		p->attr = ip.attr;
+		switch (ip.attr) {
+		case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT:
+		case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT:
+			/* Only out and in/out values can be updated */
+			p->u.value.a = ip.a;
+			p->u.value.b = ip.b;
+			p->u.value.c = ip.c;
+			break;
+		case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT:
+		case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT:
+			/*
+			 * Only the size of the memref can be updated.
+			 * Since we don't have access to the original
+			 * parameters here, only store the supplied size.
+			 * The driver will copy the updated size into the
+			 * original parameters.
+			 */
+			p->u.memref.shm = NULL;
+			p->u.memref.shm_offs = 0;
+			p->u.memref.size = ip.b;
+			break;
+		default:
+			memset(&p->u, 0, sizeof(p->u));
+			break;
+		}
+	}
+	return 0;
+}
+
+static int tee_ioctl_supp_send(struct tee_context *ctx,
+			       struct tee_ioctl_buf_data __user *ubuf)
+{
+	long rc;
+	struct tee_ioctl_buf_data buf;
+	struct tee_iocl_supp_send_arg __user *uarg;
+	struct tee_param *params;
+	u32 num_params;
+	u32 ret;
+
+	/* Not valid for this driver */
+	if (!ctx->teedev->desc->ops->supp_send)
+		return -EINVAL;
+
+	if (copy_from_user(&buf, ubuf, sizeof(buf)))
+		return -EFAULT;
+
+	if (buf.buf_len > TEE_MAX_ARG_SIZE ||
+	    buf.buf_len < sizeof(struct tee_iocl_supp_send_arg))
+		return -EINVAL;
+
+	uarg = u64_to_user_ptr(buf.buf_ptr);
+	if (get_user(ret, &uarg->ret) ||
+	    get_user(num_params, &uarg->num_params))
+		return -EFAULT;
+
+	if (sizeof(*uarg) + TEE_IOCTL_PARAM_SIZE(num_params) > buf.buf_len)
+		return -EINVAL;
+
+	params = kcalloc(num_params, sizeof(struct tee_param), GFP_KERNEL);
+	if (!params)
+		return -ENOMEM;
+
+	rc = params_from_supp(params, num_params, uarg->params);
+	if (rc)
+		goto out;
+
+	rc = ctx->teedev->desc->ops->supp_send(ctx, ret, num_params, params);
+out:
+	kfree(params);
+	return rc;
+}
+
+static long tee_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	struct tee_context *ctx = filp->private_data;
+	void __user *uarg = (void __user *)arg;
+
+	switch (cmd) {
+	case TEE_IOC_VERSION:
+		return tee_ioctl_version(ctx, uarg);
+	case TEE_IOC_SHM_ALLOC:
+		return tee_ioctl_shm_alloc(ctx, uarg);
+	case TEE_IOC_OPEN_SESSION:
+		return tee_ioctl_open_session(ctx, uarg);
+	case TEE_IOC_INVOKE:
+		return tee_ioctl_invoke(ctx, uarg);
+	case TEE_IOC_CANCEL:
+		return tee_ioctl_cancel(ctx, uarg);
+	case TEE_IOC_CLOSE_SESSION:
+		return tee_ioctl_close_session(ctx, uarg);
+	case TEE_IOC_SUPPL_RECV:
+		return tee_ioctl_supp_recv(ctx, uarg);
+	case TEE_IOC_SUPPL_SEND:
+		return tee_ioctl_supp_send(ctx, uarg);
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct file_operations tee_fops = {
+	.owner = THIS_MODULE,
+	.open = tee_open,
+	.release = tee_release,
+	.unlocked_ioctl = tee_ioctl,
+	.compat_ioctl = tee_ioctl,
+};
+
+static void tee_release_device(struct device *dev)
+{
+	struct tee_device *teedev = container_of(dev, struct tee_device, dev);
+
+	spin_lock(&driver_lock);
+	clear_bit(teedev->id, dev_mask);
+	spin_unlock(&driver_lock);
+	mutex_destroy(&teedev->mutex);
+	idr_destroy(&teedev->idr);
+	kfree(teedev);
+}
+
+/**
+ * tee_device_alloc() - Allocate a new struct tee_device instance
+ * @teedesc:	Descriptor for this driver
+ * @dev:	Parent device for this device
+ * @pool:	Shared memory pool, NULL if not used
+ * @driver_data: Private driver data for this device
+ *
+ * Allocates a new struct tee_device instance. The device is
+ * removed by tee_device_unregister().
+ *
+ * @returns a pointer to a 'struct tee_device' or an ERR_PTR on failure
+ */
+struct tee_device *tee_device_alloc(const struct tee_desc *teedesc,
+				    struct device *dev,
+				    struct tee_shm_pool *pool,
+				    void *driver_data)
+{
+	struct tee_device *teedev;
+	void *ret;
+	int rc;
+	int offs = 0;
+
+	if (!teedesc || !teedesc->name || !teedesc->ops ||
+	    !teedesc->ops->get_version || !teedesc->ops->open ||
+	    !teedesc->ops->release || !pool)
+		return ERR_PTR(-EINVAL);
+
+	teedev = kzalloc(sizeof(*teedev), GFP_KERNEL);
+	if (!teedev) {
+		ret = ERR_PTR(-ENOMEM);
+		goto err;
+	}
+
+	if (teedesc->flags & TEE_DESC_PRIVILEGED)
+		offs = TEE_NUM_DEVICES / 2;
+
+	spin_lock(&driver_lock);
+	teedev->id = find_next_zero_bit(dev_mask, TEE_NUM_DEVICES, offs);
+	if (teedev->id < TEE_NUM_DEVICES)
+		set_bit(teedev->id, dev_mask);
+	spin_unlock(&driver_lock);
+
+	if (teedev->id >= TEE_NUM_DEVICES) {
+		ret = ERR_PTR(-ENOMEM);
+		goto err;
+	}
+
+	snprintf(teedev->name, sizeof(teedev->name), "tee%s%d",
+		 teedesc->flags & TEE_DESC_PRIVILEGED ? "priv" : "",
+		 teedev->id - offs);
+
+	teedev->dev.class = tee_class;
+	teedev->dev.release = tee_release_device;
+	teedev->dev.parent = dev;
+
+	teedev->dev.devt = MKDEV(MAJOR(tee_devt), teedev->id);
+
+	rc = dev_set_name(&teedev->dev, "%s", teedev->name);
+	if (rc) {
+		ret = ERR_PTR(rc);
+		goto err_devt;
+	}
+
+	cdev_init(&teedev->cdev, &tee_fops);
+	teedev->cdev.owner = teedesc->owner;
+	teedev->cdev.kobj.parent = &teedev->dev.kobj;
+
+	dev_set_drvdata(&teedev->dev, driver_data);
+	device_initialize(&teedev->dev);
+
+	/* 1 as tee_device_unregister() does one final tee_device_put() */
+	teedev->num_users = 1;
+	init_completion(&teedev->c_no_users);
+	mutex_init(&teedev->mutex);
+	idr_init(&teedev->idr);
+
+	teedev->desc = teedesc;
+	teedev->pool = pool;
+
+	return teedev;
+err_devt:
+	unregister_chrdev_region(teedev->dev.devt, 1);
+err:
+	pr_err("could not register %s driver\n",
+	       teedesc->flags & TEE_DESC_PRIVILEGED ? "privileged" : "client");
+	if (teedev && teedev->id < TEE_NUM_DEVICES) {
+		spin_lock(&driver_lock);
+		clear_bit(teedev->id, dev_mask);
+		spin_unlock(&driver_lock);
+	}
+	kfree(teedev);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(tee_device_alloc);
+
+static ssize_t implementation_id_show(struct device *dev,
+				      struct device_attribute *attr, char *buf)
+{
+	struct tee_device *teedev = container_of(dev, struct tee_device, dev);
+	struct tee_ioctl_version_data vers;
+
+	teedev->desc->ops->get_version(teedev, &vers);
+	return scnprintf(buf, PAGE_SIZE, "%d\n", vers.impl_id);
+}
+static DEVICE_ATTR_RO(implementation_id);
+
+static struct attribute *tee_dev_attrs[] = {
+	&dev_attr_implementation_id.attr,
+	NULL
+};
+
+static const struct attribute_group tee_dev_group = {
+	.attrs = tee_dev_attrs,
+};
+
+/**
+ * tee_device_register() - Registers a TEE device
+ * @teedev:	Device to register
+ *
+ * tee_device_unregister() need to be called to remove the @teedev if
+ * this function fails.
+ *
+ * @returns < 0 on failure
+ */
+int tee_device_register(struct tee_device *teedev)
+{
+	int rc;
+
+	if (teedev->flags & TEE_DEVICE_FLAG_REGISTERED) {
+		dev_err(&teedev->dev, "attempt to register twice\n");
+		return -EINVAL;
+	}
+
+	rc = cdev_add(&teedev->cdev, teedev->dev.devt, 1);
+	if (rc) {
+		dev_err(&teedev->dev,
+			"unable to cdev_add() %s, major %d, minor %d, err=%d\n",
+			teedev->name, MAJOR(teedev->dev.devt),
+			MINOR(teedev->dev.devt), rc);
+		return rc;
+	}
+
+	rc = device_add(&teedev->dev);
+	if (rc) {
+		dev_err(&teedev->dev,
+			"unable to device_add() %s, major %d, minor %d, err=%d\n",
+			teedev->name, MAJOR(teedev->dev.devt),
+			MINOR(teedev->dev.devt), rc);
+		goto err_device_add;
+	}
+
+	rc = sysfs_create_group(&teedev->dev.kobj, &tee_dev_group);
+	if (rc) {
+		dev_err(&teedev->dev,
+			"failed to create sysfs attributes, err=%d\n", rc);
+		goto err_sysfs_create_group;
+	}
+
+	teedev->flags |= TEE_DEVICE_FLAG_REGISTERED;
+	return 0;
+
+err_sysfs_create_group:
+	device_del(&teedev->dev);
+err_device_add:
+	cdev_del(&teedev->cdev);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(tee_device_register);
+
+void tee_device_put(struct tee_device *teedev)
+{
+	mutex_lock(&teedev->mutex);
+	/* Shouldn't put in this state */
+	if (!WARN_ON(!teedev->desc)) {
+		teedev->num_users--;
+		if (!teedev->num_users) {
+			teedev->desc = NULL;
+			complete(&teedev->c_no_users);
+		}
+	}
+	mutex_unlock(&teedev->mutex);
+}
+
+bool tee_device_get(struct tee_device *teedev)
+{
+	mutex_lock(&teedev->mutex);
+	if (!teedev->desc) {
+		mutex_unlock(&teedev->mutex);
+		return false;
+	}
+	teedev->num_users++;
+	mutex_unlock(&teedev->mutex);
+	return true;
+}
+
+/**
+ * tee_device_unregister() - Removes a TEE device
+ * @teedev:	Device to unregister
+ *
+ * This function should be called to remove the @teedev even if
+ * tee_device_register() hasn't been called yet. Does nothing if
+ * @teedev is NULL.
+ */
+void tee_device_unregister(struct tee_device *teedev)
+{
+	if (!teedev)
+		return;
+
+	if (teedev->flags & TEE_DEVICE_FLAG_REGISTERED) {
+		sysfs_remove_group(&teedev->dev.kobj, &tee_dev_group);
+		cdev_del(&teedev->cdev);
+		device_del(&teedev->dev);
+	}
+
+	tee_device_put(teedev);
+	wait_for_completion(&teedev->c_no_users);
+
+	/*
+	 * No need to take a mutex any longer now since teedev->desc was
+	 * set to NULL before teedev->c_no_users was completed.
+	 */
+
+	teedev->pool = NULL;
+
+	put_device(&teedev->dev);
+}
+EXPORT_SYMBOL_GPL(tee_device_unregister);
+
+/**
+ * tee_get_drvdata() - Return driver_data pointer
+ * @teedev:	Device containing the driver_data pointer
+ * @returns the driver_data pointer supplied to tee_register().
+ */
+void *tee_get_drvdata(struct tee_device *teedev)
+{
+	return dev_get_drvdata(&teedev->dev);
+}
+EXPORT_SYMBOL_GPL(tee_get_drvdata);
+
+static int __init tee_init(void)
+{
+	int rc;
+
+	tee_class = class_create(THIS_MODULE, "tee");
+	if (IS_ERR(tee_class)) {
+		pr_err("couldn't create class\n");
+		return PTR_ERR(tee_class);
+	}
+
+	rc = alloc_chrdev_region(&tee_devt, 0, TEE_NUM_DEVICES, "tee");
+	if (rc) {
+		pr_err("failed to allocate char dev region\n");
+		class_destroy(tee_class);
+		tee_class = NULL;
+	}
+
+	return rc;
+}
+
+static void __exit tee_exit(void)
+{
+	class_destroy(tee_class);
+	tee_class = NULL;
+	unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
+}
+
+subsys_initcall(tee_init);
+module_exit(tee_exit);
+
+MODULE_AUTHOR("Linaro");
+MODULE_DESCRIPTION("TEE Driver");
+MODULE_VERSION("1.0");
+MODULE_LICENSE("GPL v2");