hwrng: optee - remove redundant initialization to variable rng_size

Variable rng_size is being initialized with a value that is never read,
the variable is being re-assigned later on. The initialization is
redundant and can be removed.

Cleans up cppcheck warning:
Variable 'rng_size' is assigned a value that is never used.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: optee-rng: use tee_shm_alloc_kernel_buf()

Uses the new simplified tee_shm_alloc_kernel_buf() function instead of
the old deprecated tee_shm_alloc() function which required specific
TEE_SHM-flags.

Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

hwrng: optee - Use device-managed registration API

Use devm_hwrng_register to get rid of manual unregistration.

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: optee - fix wait use case

The current code waits for data to be available before attempting a
second read. However the second read would not be executed as the
while loop will exit.

This fix does not wait if all data has been read (skips the call to
msleep(0)) and reads a second time if partial data was retrieved on
the first read.

Worth noticing that since msleep(0) schedules a one jiffy timeout is
better to skip such a call.

Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: optee - handle unlimited data rates

Data rates of MAX_UINT32 will schedule an unnecessary one jiffy
timeout on the call to msleep. Avoid this scenario by using 0 as the
unlimited data rate.

Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: optee - Use UUID API for exporting the UUID

There is export_uuid() function which exports uuid_t to the u8 array.
Use it instead of open coding variant.

This allows to hide the uuid_t internals.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: make symbol 'optee_rng_id_table' static

Fixes the following sparse warning:

drivers/char/hw_random/optee-rng.c:265:35: warning:
symbol 'optee_rng_id_table' was not declared. Should it be static?

Fixes: 5fe8b1cc6a03 ("hwrng: add OP-TEE based rng driver")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

hwrng: Fix unsigned comparison with less than zero

The return from the call to tee_client_invoke_func can be a
negative error code however this is being assigned to an
unsigned variable 'ret' hence the check is always false.
Fix this by making 'ret' an int.

Detected by Coccinelle ("Unsigned expression compared with zero:
ret < 0")

Fixes: 5fe8b1cc6a03 ("hwrng: add OP-TEE based rng driver")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

hwrng: optee: Initialize some structs using memset instead of braces

Clang warns:

drivers/char/hw_random/optee-rng.c:80:31: warning: suggest braces around
initialization of subobject [-Wmissing-braces]
struct tee_param param[4] = {0};
^
{}
drivers/char/hw_random/optee-rng.c:177:31: warning: suggest braces
around initialization of subobject [-Wmissing-braces]
struct tee_param param[4] = {0};
^
{}
drivers/char/hw_random/optee-rng.c:212:48: warning: suggest braces
around initialization of subobject [-Wmissing-braces]
struct tee_ioctl_open_session_arg sess_arg = {0};
^
{}
3 warnings generated.

One way to fix these warnings is to add additional braces like Clang
suggests; however, there has been a bit of push back from some
maintainers, who just prefer memset as it is unambiguous, doesn't
depend on a particular compiler version, and properly initializes all
subobjects [1][2]. Do that here so there are no more warnings.

[1]: https://lore.kernel.org/lkml/022e41c0-8465-dc7a-a45c-64187ecd9684@amd.com/
[2]: https://lore.kernel.org/lkml/20181128.215241.702406654469517539.davem@davemloft.net/

Fixes: 5fe8b1cc6a03 ("hwrng: add OP-TEE based rng driver")
Link: https://github.com/ClangBuiltLinux/linux/issues/369
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

hwrng: add OP-TEE based rng driver

On ARM SoC's with TrustZone enabled, peripherals like entropy sources
might not be accessible to normal world (linux in this case) and rather
accessible to secure world (OP-TEE in this case) only. So this driver
aims to provides a generic interface to OP-TEE based random number
generator service.

This driver registers on TEE bus to interact with OP-TEE based rng
device/service.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>