tee: optee: add TEE bus device enumeration support

OP-TEE provides a pseudo TA to enumerate TAs which can act as devices/
services for TEE bus. So implement device enumeration using invoke
function: PTA_CMD_GET_DEVICES provided by pseudo TA to fetch array of
device UUIDs. Also register these enumerated devices with TEE bus as
"optee-clntX" device.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
[jw: fix optee_enumerate_devices() with no devices found]
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

drivers/tee/optee/Makefile

@@ -5,3 +5,4 @@ optee-objs += call.o
 optee-objs += rpc.o
 optee-objs += supp.o
 optee-objs += shm_pool.o
+optee-objs += device.o

drivers/tee/optee/core.c

@@ -634,6 +634,10 @@ static struct optee *optee_probe(struct device_node *np)
 	if (optee->sec_caps & OPTEE_SMC_SEC_CAP_DYNAMIC_SHM)
 		pr_info("dynamic shared memory is enabled\n");
 
+	rc = optee_enumerate_devices();
+	if (rc)
+		goto err;
+
 	pr_info("initialized driver\n");
 	return optee;
 err:

drivers/tee/optee/device.c

@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Linaro Ltd.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/tee_drv.h>
+#include <linux/uuid.h>
+#include "optee_private.h"
+
+/*
+ * Get device UUIDs
+ *
+ * [out]     memref[0]        Array of device UUIDs
+ *
+ * Return codes:
+ * TEE_SUCCESS - Invoke command success
+ * TEE_ERROR_BAD_PARAMETERS - Incorrect input param
+ * TEE_ERROR_SHORT_BUFFER - Output buffer size less than required
+ */
+#define PTA_CMD_GET_DEVICES		0x0
+
+static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
+{
+	if (ver->impl_id == TEE_IMPL_ID_OPTEE)
+		return 1;
+	else
+		return 0;
+}
+
+static int get_devices(struct tee_context *ctx, u32 session,
+		       struct tee_shm *device_shm, u32 *shm_size)
+{
+	u32 ret = 0;
+	struct tee_ioctl_invoke_arg inv_arg = {0};
+	struct tee_param param[4] = {0};
+
+	/* Invoke PTA_CMD_GET_DEVICES function */
+	inv_arg.func = PTA_CMD_GET_DEVICES;
+	inv_arg.session = session;
+	inv_arg.num_params = 4;
+
+	/* Fill invoke cmd params */
+	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
+	param[0].u.memref.shm = device_shm;
+	param[0].u.memref.size = *shm_size;
+	param[0].u.memref.shm_offs = 0;
+
+	ret = tee_client_invoke_func(ctx, &inv_arg, param);
+	if ((ret < 0) || ((inv_arg.ret != TEEC_SUCCESS) &&
+			  (inv_arg.ret != TEEC_ERROR_SHORT_BUFFER))) {
+		pr_err("PTA_CMD_GET_DEVICES invoke function err: %x\n",
+		       inv_arg.ret);
+		return -EINVAL;
+	}
+
+	*shm_size = param[0].u.memref.size;
+
+	return 0;
+}
+
+static int optee_register_device(const uuid_t *device_uuid, u32 device_id)
+{
+	struct tee_client_device *optee_device = NULL;
+	int rc;
+
+	optee_device = kzalloc(sizeof(*optee_device), GFP_KERNEL);
+	if (!optee_device)
+		return -ENOMEM;
+
+	optee_device->dev.bus = &tee_bus_type;
+	dev_set_name(&optee_device->dev, "optee-clnt%u", device_id);
+	uuid_copy(&optee_device->id.uuid, device_uuid);
+
+	rc = device_register(&optee_device->dev);
+	if (rc) {
+		pr_err("device registration failed, err: %d\n", rc);
+		kfree(optee_device);
+	}
+
+	return rc;
+}
+
+int optee_enumerate_devices(void)
+{
+	const uuid_t pta_uuid =
+		UUID_INIT(0x7011a688, 0xddde, 0x4053,
+			  0xa5, 0xa9, 0x7b, 0x3c, 0x4d, 0xdf, 0x13, 0xb8);
+	struct tee_ioctl_open_session_arg sess_arg = {0};
+	struct tee_shm *device_shm = NULL;
+	const uuid_t *device_uuid = NULL;
+	struct tee_context *ctx = NULL;
+	u32 shm_size = 0, idx, num_devices = 0;
+	int rc;
+
+	/* Open context with OP-TEE driver */
+	ctx = tee_client_open_context(NULL, optee_ctx_match, NULL, NULL);
+	if (IS_ERR(ctx))
+		return -ENODEV;
+
+	/* Open session with device enumeration pseudo TA */
+	memcpy(sess_arg.uuid, pta_uuid.b, TEE_IOCTL_UUID_LEN);
+	sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC;
+	sess_arg.num_params = 0;
+
+	rc = tee_client_open_session(ctx, &sess_arg, NULL);
+	if ((rc < 0) || (sess_arg.ret != TEEC_SUCCESS)) {
+		/* Device enumeration pseudo TA not found */
+		rc = 0;
+		goto out_ctx;
+	}
+
+	rc = get_devices(ctx, sess_arg.session, NULL, &shm_size);
+	if (rc < 0 || !shm_size)
+		goto out_sess;
+
+	device_shm = tee_shm_alloc(ctx, shm_size,
+				   TEE_SHM_MAPPED | TEE_SHM_DMA_BUF);
+	if (IS_ERR(device_shm)) {
+		pr_err("tee_shm_alloc failed\n");
+		rc = PTR_ERR(device_shm);
+		goto out_sess;
+	}
+
+	rc = get_devices(ctx, sess_arg.session, device_shm, &shm_size);
+	if (rc < 0)
+		goto out_shm;
+
+	device_uuid = tee_shm_get_va(device_shm, 0);
+	if (IS_ERR(device_uuid)) {
+		pr_err("tee_shm_get_va failed\n");
+		rc = PTR_ERR(device_uuid);
+		goto out_shm;
+	}
+
+	num_devices = shm_size / sizeof(uuid_t);
+
+	for (idx = 0; idx < num_devices; idx++) {
+		rc = optee_register_device(&device_uuid[idx], idx);
+		if (rc)
+			goto out_shm;
+	}
+
+out_shm:
+	tee_shm_free(device_shm);
+out_sess:
+	tee_client_close_session(ctx, sess_arg.session);
+out_ctx:
+	tee_client_close_context(ctx);
+
+	return rc;
+}

drivers/tee/optee/optee_private.h

@@ -28,6 +28,7 @@
 #define TEEC_ERROR_BAD_PARAMETERS	0xFFFF0006
 #define TEEC_ERROR_COMMUNICATION	0xFFFF000E
 #define TEEC_ERROR_OUT_OF_MEMORY	0xFFFF000C
+#define TEEC_ERROR_SHORT_BUFFER		0xFFFF0010
 
 #define TEEC_ORIGIN_COMMS		0x00000002
 
@@ -181,6 +182,8 @@ void optee_free_pages_list(void *array, size_t num_entries);
 void optee_fill_pages_list(u64 *dst, struct page **pages, int num_pages,
 			   size_t page_offset);
 
+int optee_enumerate_devices(void);
+
 /*
  * Small helpers
  */