Hi Simon,
On 9/12/22 20:31, Simon Glass wrote:
Hi Ilias,
On Wed, 7 Sept 2022 at 15:32, Ilias Apalodimas ilias.apalodimas@linaro.org wrote:
Hi Simon,
On Thu, 8 Sept 2022 at 00:11, Simon Glass sjg@chromium.org wrote:
Hi Ilias,
On Tue, 6 Sept 2022 at 15:23, Ilias Apalodimas ilias.apalodimas@linaro.org wrote:
Hi Simon,
On Tue, Sep 06, 2022 at 03:18:28PM -0600, Simon Glass wrote:
Hi,
On Tue, 6 Sept 2022 at 03:37, Ilias Apalodimas ilias.apalodimas@linaro.org wrote:
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 whichwe 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@linaro.org Reviewed-by: Jens Wiklander jens.wiklander@linaro.org Reviewed-by: Etienne Carriere etienne.carriere@linaro.org
Changes since v3:
- Use NULL instead of a child ptr on device_bind_driver(), since
it's not really needed
- Changed the style of the optee_bus_probe[] definition to
{.drv_name = xxx, .dev_name = yyy }
Changes since v2:
- Fixed typo on driver name ftpm-tee -> ftpm_tee
Changes since v1:
- remove a macro and use ARRAY_SIZE directly
drivers/tee/optee/core.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-)
diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c index a89d62aaf0b3..c201a4635e6b 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
- { .drv_name = "optee-rng", .dev_name = "optee-rng" },
+#endif +#ifdef CONFIG_TPM2_FTPM_TEE
- { .drv_name = "ftpm_tee", .dev_name = "ftpm_tee" },
+#endif +};
struct rpc_param { u32 a0; u32 a1; @@ -642,8 +654,7 @@ 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 +683,13 @@ 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-TEETA
*/
- 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, NULL);
if (ret)
- return ret;
- dev_warn(dev, "Failed to bind device %s\n",
- optee_bus_probe[i].dev_name);
Please add device tree nodes for these and all this code can go away.
That's the exact opposite of what the commit message describes. OP-TEE supports a scannable bus ifor TAs that behave like hardware blocks and doesn't need a DT entry. Since it's really the TAs compilation decision to support that or not having them as a DT node is not always the right choice.
This is continuing the perversion of how things are supposed to work in driver model.
Which is not the only thing we need to keep in mind though.
We need to talk about this because it is simply the wrong way to be approaching this.
This is already part of other software components though, e.g it's already in the kernel. So I don't think it's the wrong approach.
There is nothing wrong with putting things in the DT and this is how U-Boot works. For now, please create a binding and get it reviewed. You don't need all the internal objects but you do need an OP-TEE driver and node, as we have with PCI.
Some things *are* working without a DT entry. You had similar concerns on FF-A (where you requested a DT node again) and people gave the exact same response. As long as a bus is scanable in any way, it's preferable to than adding a DT entry. Moreover this code does not prevent anyone from adding a DT entry.
To make things even worse if the TA is compiled as 'scanable' and has a DT entry, it might cause issues down the road when being probed by the kernel. So really this is just a patch that makes u-boot behave and plug in properly to the rest of the ecosystem
Calling device_bind() is supposed to be used in extremis. I don't see any scanning of an OP-TEE bus here. I just see it binding two child devices which are hard-coded in U-Boot. What am I missing?
The tee bus is supported in Linux kernel (each TA have a UUID and
is discoverable by the TEE driver).
see drivers/tee/optee/core.c::optee_bus_scan()
and "struct tee_client_driver" with TA UUID
It wasn't supported in U-Boot is the first TEE/OP-TEE driver implementation
=> TA support was hardcoded, under the associated CONFIG
and the probe failed when the TA is not present.
for example, I add this binding for TA_RNG in drivers/rng/optee_rng.c
The TEE bus feature is added by the Etienne in the serie [1].
This bus is more flexible and avoid OP-TEE to dynamically modify the device tree
to add/remove the supported SW component (TA support are activated during OP-TEE
compilation) as the binding is managed dynamically in OP-TEE as it is done in Linux.
For information, on STM32MP15 platform, I have the trace "can't open session:" for
RNG TA for each 'rng' command when this TA is not supported in OP-TEE but
OP-TEE RNG driver is activated in U-Boot, because the driver is binding.
[1] drivers: tee: optee: remove unused probe local variable
http://patchwork.ozlabs.org/project/uboot/list/?series=311351&state=*
This appears to be a Linaro binding, so you should be able to update it easily enough.
Regards, Simon
Regards Patrick