Re: [PATCH v4] tee: optee: rework TA bus scanning code

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 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@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-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, 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.

Thanks /Ilias

Regards, Simon