[RFC PATCH 1/2] optee: model OP-TEE as a platform device/driver

[Ard Biesheuvel]

To simplify adding ACPI support to the OP-TEE driver, model it as
a platform driver. This will permit us to use the generic device
property layer for parsing additional properties, regardless of
whether DT or ACPI is being used.

Note that this change will result in the OP-TEE driver to be loaded
automatically on systems that advertise the presence of OP-TEE via
the device tree.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
 drivers/tee/optee/core.c | 86 ++++++++------------
 1 file changed, 32 insertions(+), 54 deletions(-)

diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
index e1aafe842d66..61ea65cfaedd 100644
--- a/drivers/tee/optee/core.c
+++ b/drivers/tee/optee/core.c
@@ -529,13 +529,13 @@ static void optee_smccc_hvc(unsigned long a0, unsigned long a1,
 	arm_smccc_hvc(a0, a1, a2, a3, a4, a5, a6, a7, res);
 }
 
-static optee_invoke_fn *get_invoke_func(struct device_node *np)
+static optee_invoke_fn *get_invoke_func(struct device *dev)
 {
 	const char *method;
 
-	pr_info("probing for conduit method from DT.\n");
+	pr_info("probing for conduit method.\n");
 
-	if (of_property_read_string(np, "method", &method)) {
+	if (device_property_read_string(dev, "method", &method)) {
 		pr_warn("missing \"method\" property\n");
 		return ERR_PTR(-ENXIO);
 	}
@@ -549,7 +549,7 @@ static optee_invoke_fn *get_invoke_func(struct device_node *np)
 	return ERR_PTR(-EINVAL);
 }
 
-static struct optee *optee_probe(struct device_node *np)
+static int optee_probe(struct platform_device *pdev)
 {
 	optee_invoke_fn *invoke_fn;
 	struct tee_shm_pool *pool;
@@ -559,25 +559,25 @@ static struct optee *optee_probe(struct device_node *np)
 	u32 sec_caps;
 	int rc;
 
-	invoke_fn = get_invoke_func(np);
+	invoke_fn = get_invoke_func(&pdev->dev);
 	if (IS_ERR(invoke_fn))
-		return (void *)invoke_fn;
+		return PTR_ERR(invoke_fn);
 
 	if (!optee_msg_api_uid_is_optee_api(invoke_fn)) {
 		pr_warn("api uid mismatch\n");
-		return ERR_PTR(-EINVAL);
+		return -EINVAL;
 	}
 
 	optee_msg_get_os_revision(invoke_fn);
 
 	if (!optee_msg_api_revision_is_compatible(invoke_fn)) {
 		pr_warn("api revision mismatch\n");
-		return ERR_PTR(-EINVAL);
+		return -EINVAL;
 	}
 
 	if (!optee_msg_exchange_capabilities(invoke_fn, &sec_caps)) {
 		pr_warn("capabilities mismatch\n");
-		return ERR_PTR(-EINVAL);
+		return -EINVAL;
 	}
 
 	/*
@@ -585,11 +585,11 @@ static struct optee *optee_probe(struct device_node *np)
 	 * doesn't have any reserved memory we can use we can't continue.
 	 */
 	if (!(sec_caps & OPTEE_SMC_SEC_CAP_HAVE_RESERVED_SHM))
-		return ERR_PTR(-EINVAL);
+		return -EINVAL;
 
 	pool = optee_config_shm_memremap(invoke_fn, &memremaped_shm, sec_caps);
 	if (IS_ERR(pool))
-		return (void *)pool;
+		return PTR_ERR(pool);
 
 	optee = kzalloc(sizeof(*optee), GFP_KERNEL);
 	if (!optee) {
@@ -600,6 +600,8 @@ static struct optee *optee_probe(struct device_node *np)
 	optee->invoke_fn = invoke_fn;
 	optee->sec_caps = sec_caps;
 
+	platform_set_drvdata(pdev, optee);
+
 	teedev = tee_device_alloc(&optee_desc, NULL, pool, optee);
 	if (IS_ERR(teedev)) {
 		rc = PTR_ERR(teedev);
@@ -632,7 +634,7 @@ static struct optee *optee_probe(struct device_node *np)
 	optee_enable_shm_cache(optee);
 
 	pr_info("initialized driver\n");
-	return optee;
+	return 0;
 err:
 	if (optee) {
 		/*
@@ -648,11 +650,13 @@ static struct optee *optee_probe(struct device_node *np)
 		tee_shm_pool_free(pool);
 	if (memremaped_shm)
 		memunmap(memremaped_shm);
-	return ERR_PTR(rc);
+	return rc;
 }
 
-static void optee_remove(struct optee *optee)
+static int optee_remove(struct platform_device *pdev)
 {
+	struct optee *optee = platform_get_drvdata(pdev);
+
 	/*
 	 * Ask OP-TEE to free all cached shared memory objects to decrease
 	 * reference counters and also avoid wild pointers in secure world
@@ -675,51 +679,25 @@ static void optee_remove(struct optee *optee)
 	mutex_destroy(&optee->call_queue.mutex);
 
 	kfree(optee);
+
+	return 0;
 }
 
-static const struct of_device_id optee_match[] = {
+static const struct of_device_id optee_dt_match[] = {
 	{ .compatible = "linaro,optee-tz" },
 	{},
 };
-
-static struct optee *optee_svc;
-
-static int __init optee_driver_init(void)
-{
-	struct device_node *fw_np;
-	struct device_node *np;
-	struct optee *optee;
-
-	/* Node is supposed to be below /firmware */
-	fw_np = of_find_node_by_name(NULL, "firmware");
-	if (!fw_np)
-		return -ENODEV;
-
-	np = of_find_matching_node(fw_np, optee_match);
-	if (!np)
-		return -ENODEV;
-
-	optee = optee_probe(np);
-	of_node_put(np);
-
-	if (IS_ERR(optee))
-		return PTR_ERR(optee);
-
-	optee_svc = optee;
-
-	return 0;
-}
-module_init(optee_driver_init);
-
-static void __exit optee_driver_exit(void)
-{
-	struct optee *optee = optee_svc;
-
-	optee_svc = NULL;
-	if (optee)
-		optee_remove(optee);
-}
-module_exit(optee_driver_exit);
+MODULE_DEVICE_TABLE(of, optee_dt_match);
+
+static struct platform_driver optee_driver = {
+	.probe  = optee_probe,
+	.remove = optee_remove,
+	.driver = {
+		.name = "optee",
+		.of_match_table = optee_dt_match,
+	},
+};
+module_platform_driver(optee_driver);
 
 MODULE_AUTHOR("Linaro");
 MODULE_DESCRIPTION("OP-TEE driver");
-- 
2.19.2