[PATCH v3] tee: optee: rework TA bus scanning code

[Ilias Apalodimas]

Late versions of OP-TEE support a pseudo bus.  TAs that behave as
hardware blocks (e.g TPM, RNG etc) present themselves on a bus which we can
scan.  Unfortunately U-Boot doesn't support that yet. It's worth noting
that we already have a workaround for RNG.  The details are in
commit 70812bb83da6 ("tee: optee: bind rng optee driver")

So let's add a list of devices based on U-Boot Kconfig options that we will
scan until we properly implement the tee-bus functionality.

While at it change the behaviour of the tee core itself wrt to device
binding.  If some device binding fails, print a warning instead of
disabling OP-TEE.

Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander at linaro.org>
---
Changes since v:2
- Fixed typo on driver name ftpm-tee -> ftpm_tee

Changes since v1:
- remove a macro and use ARRAY_SIZE directly
- print a warning instead of disabling op-tee if a driver binding fails
 drivers/tee/optee/core.c | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
index a89d62aaf0b3..1437ba1b676b 100644
--- a/drivers/tee/optee/core.c
+++ b/drivers/tee/optee/core.c
@@ -31,6 +31,18 @@ struct optee_pdata {
 	optee_invoke_fn *invoke_fn;
 };
 
+static const struct {
+	const char *drv_name;
+	const char *dev_name;
+} optee_bus_probe[] = {
+#ifdef CONFIG_RNG_OPTEE
+	{ "optee-rng", "optee-rng" },
+#endif
+#ifdef CONFIG_TPM2_FTPM_TEE
+	{ "ftpm_tee", "ftpm_tee" },
+#endif
+};
+
 struct rpc_param {
 	u32	a0;
 	u32	a1;
@@ -643,7 +655,7 @@ static int optee_probe(struct udevice *dev)
 	struct optee_pdata *pdata = dev_get_plat(dev);
 	u32 sec_caps;
 	struct udevice *child;
-	int ret;
+	int ret, i;
 
 	if (!is_optee_api(pdata->invoke_fn)) {
 		dev_err(dev, "OP-TEE api uid mismatch\n");
@@ -672,10 +684,13 @@ static int optee_probe(struct udevice *dev)
 	 * in U-Boot, the discovery of TA on the TEE bus is not supported:
 	 * only bind the drivers associated to the supported OP-TEE TA
 	 */
-	if (IS_ENABLED(CONFIG_RNG_OPTEE)) {
-		ret = device_bind_driver(dev, "optee-rng", "optee-rng", &child);
+
+	for (i = 0; i < ARRAY_SIZE(optee_bus_probe); i++) {
+		ret = device_bind_driver(dev, optee_bus_probe[i].drv_name,
+					 optee_bus_probe[i].dev_name, &child);
 		if (ret)
-			return ret;
+			dev_warn(dev, "Failed to bind device %s\n",
+				 optee_bus_probe[i].dev_name);
 	}
 
 	return 0;
-- 
2.34.1