[PATCH v7 06/11] firmware: qcom: scm: add support for object invocation

[Amirreza Zarrabi <amirreza.zarrabi@oss.qualcomm.com>]

Qualcomm TEE (QTEE) hosts Trusted Applications (TAs) and services in
the secure world, accessed via objects. A QTEE client can invoke these
objects to request services. Similarly, QTEE can request services from
the nonsecure world using objects exported to the secure world.

Add low-level primitives to facilitate the invocation of objects hosted
in QTEE, as well as those hosted in the nonsecure world.

If support for object invocation is available, the qcom_scm allocates
a dedicated child platform device. The driver for this device communicates
with QTEE using low-level primitives.

Tested-by: Neil Armstrong <neil.armstrong@linaro.org>
Tested-by: Harshal Dev <quic_hdev@quicinc.com>
Signed-off-by: Amirreza Zarrabi <amirreza.zarrabi@oss.qualcomm.com>
---
 drivers/firmware/qcom/qcom_scm.c       | 128 +++++++++++++++++++++++++++++++++
 drivers/firmware/qcom/qcom_scm.h       |   7 ++
 include/linux/firmware/qcom/qcom_scm.h |   6 ++
 3 files changed, 141 insertions(+)

diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
index edeae6cdcf31..96d5cf40a74c 100644
--- a/drivers/firmware/qcom/qcom_scm.c
+++ b/drivers/firmware/qcom/qcom_scm.c
@@ -2094,6 +2094,124 @@ static int qcom_scm_qseecom_init(struct qcom_scm *scm)
 
 #endif /* CONFIG_QCOM_QSEECOM */
 
+/**
+ * qcom_scm_qtee_invoke_smc() - Invoke a QTEE object.
+ * @inbuf: start address of memory area used for inbound buffer.
+ * @inbuf_size: size of the memory area used for inbound buffer.
+ * @outbuf: start address of memory area used for outbound buffer.
+ * @outbuf_size: size of the memory area used for outbound buffer.
+ * @result: result of QTEE object invocation.
+ * @response_type: response type returned by QTEE.
+ *
+ * @response_type determines how the contents of @inbuf and @outbuf
+ * should be processed.
+ *
+ * Return: On success, return 0 or <0 on failure.
+ */
+int qcom_scm_qtee_invoke_smc(phys_addr_t inbuf, size_t inbuf_size,
+			     phys_addr_t outbuf, size_t outbuf_size,
+			     u64 *result, u64 *response_type)
+{
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_SMCINVOKE,
+		.cmd = QCOM_SCM_SMCINVOKE_INVOKE,
+		.owner = ARM_SMCCC_OWNER_TRUSTED_OS,
+		.args[0] = inbuf,
+		.args[1] = inbuf_size,
+		.args[2] = outbuf,
+		.args[3] = outbuf_size,
+		.arginfo = QCOM_SCM_ARGS(4, QCOM_SCM_RW, QCOM_SCM_VAL,
+					 QCOM_SCM_RW, QCOM_SCM_VAL),
+	};
+	struct qcom_scm_res res;
+	int ret;
+
+	ret = qcom_scm_call(__scm->dev, &desc, &res);
+	if (ret)
+		return ret;
+
+	*response_type = res.result[0];
+	*result = res.result[1];
+
+	return 0;
+}
+EXPORT_SYMBOL(qcom_scm_qtee_invoke_smc);
+
+/**
+ * qcom_scm_qtee_callback_response() - Submit response for callback request.
+ * @buf: start address of memory area used for outbound buffer.
+ * @buf_size: size of the memory area used for outbound buffer.
+ * @result: Result of QTEE object invocation.
+ * @response_type: Response type returned by QTEE.
+ *
+ * @response_type determines how the contents of @buf should be processed.
+ *
+ * Return: On success, return 0 or <0 on failure.
+ */
+int qcom_scm_qtee_callback_response(phys_addr_t buf, size_t buf_size,
+				    u64 *result, u64 *response_type)
+{
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_SMCINVOKE,
+		.cmd = QCOM_SCM_SMCINVOKE_CB_RSP,
+		.owner = ARM_SMCCC_OWNER_TRUSTED_OS,
+		.args[0] = buf,
+		.args[1] = buf_size,
+		.arginfo = QCOM_SCM_ARGS(2, QCOM_SCM_RW, QCOM_SCM_VAL),
+	};
+	struct qcom_scm_res res;
+	int ret;
+
+	ret = qcom_scm_call(__scm->dev, &desc, &res);
+	if (ret)
+		return ret;
+
+	*response_type = res.result[0];
+	*result = res.result[1];
+
+	return 0;
+}
+EXPORT_SYMBOL(qcom_scm_qtee_callback_response);
+
+static void qcom_scm_qtee_free(void *data)
+{
+	struct platform_device *qtee_dev = data;
+
+	platform_device_unregister(qtee_dev);
+}
+
+static int qcom_scm_qtee_init(struct qcom_scm *scm)
+{
+	struct platform_device *qtee_dev;
+	u64 result, response_type;
+	int ret;
+
+	/*
+	 * Check if QTEE supports smcinvoke:
+	 * This will fail with -EINVAL due to invalid buffers, but first,
+	 * it checks whether the call is supported in QTEE syscall handler.
+	 * If not supported, -EIO is returned.
+	 */
+	ret = qcom_scm_qtee_invoke_smc(0, 0, 0, 0, &result, &response_type);
+	if (ret == -EIO)
+		return -EIO;
+
+	/* Setup QTEE interface device. */
+	qtee_dev = platform_device_alloc("qcomtee", -1);
+	if (!qtee_dev)
+		return -ENOMEM;
+
+	qtee_dev->dev.parent = scm->dev;
+
+	ret = platform_device_add(qtee_dev);
+	if (ret) {
+		platform_device_put(qtee_dev);
+		return ret;
+	}
+
+	return devm_add_action_or_reset(scm->dev, qcom_scm_qtee_free, qtee_dev);
+}
+
 /**
  * qcom_scm_is_available() - Checks if SCM is available
  */
@@ -2326,6 +2444,16 @@ static int qcom_scm_probe(struct platform_device *pdev)
 	ret = qcom_scm_qseecom_init(scm);
 	WARN(ret < 0, "failed to initialize qseecom: %d\n", ret);
 
+	/*
+	 * Initialize the QTEE object interface.
+	 *
+	 * This only represents the availability for QTEE object invocation
+	 * and callback support. On failure, ignore the result. Any subsystem
+	 * depending on it may fail if it tries to access this interface.
+	 */
+	ret = qcom_scm_qtee_init(scm);
+	WARN(ret < 0, "failed to initialize qcomtee: %d\n", ret);
+
 	return 0;
 }
 
diff --git a/drivers/firmware/qcom/qcom_scm.h b/drivers/firmware/qcom/qcom_scm.h
index 0e8dd838099e..a56c8212cc0c 100644
--- a/drivers/firmware/qcom/qcom_scm.h
+++ b/drivers/firmware/qcom/qcom_scm.h
@@ -156,6 +156,13 @@ int qcom_scm_shm_bridge_enable(struct device *scm_dev);
 #define QCOM_SCM_SVC_GPU			0x28
 #define QCOM_SCM_SVC_GPU_INIT_REGS		0x01
 
+/* ARM_SMCCC_OWNER_TRUSTED_OS calls */
+
+#define QCOM_SCM_SVC_SMCINVOKE			0x06
+#define QCOM_SCM_SMCINVOKE_INVOKE_LEGACY	0x00
+#define QCOM_SCM_SMCINVOKE_CB_RSP		0x01
+#define QCOM_SCM_SMCINVOKE_INVOKE		0x02
+
 /* common error codes */
 #define QCOM_SCM_V2_EBUSY	-12
 #define QCOM_SCM_ENOMEM		-5
diff --git a/include/linux/firmware/qcom/qcom_scm.h b/include/linux/firmware/qcom/qcom_scm.h
index 0f667bf1d4d9..a55ca771286b 100644
--- a/include/linux/firmware/qcom/qcom_scm.h
+++ b/include/linux/firmware/qcom/qcom_scm.h
@@ -175,4 +175,10 @@ static inline int qcom_scm_qseecom_app_send(u32 app_id,
 
 #endif /* CONFIG_QCOM_QSEECOM */
 
+int qcom_scm_qtee_invoke_smc(phys_addr_t inbuf, size_t inbuf_size,
+			     phys_addr_t outbuf, size_t outbuf_size,
+			     u64 *result, u64 *response_type);
+int qcom_scm_qtee_callback_response(phys_addr_t buf, size_t buf_size,
+				    u64 *result, u64 *response_type);
+
 #endif

-- 
2.34.1