On 11/1/23 15:49, Alexey Romanov wrote:

Add dm_rng_read_default() function, which obtain a series of random bytes. In some cases, such function would be useful because it allows the caller to abstract away from RNG device.

Signed-off-by: Alexey Romanov avromanov@salutedevices.com

drivers/rng/rng-uclass.c | 20 ++++++++++++++++++++ include/rng.h | 10 ++++++++++ 2 files changed, 30 insertions(+)

diff --git a/drivers/rng/rng-uclass.c b/drivers/rng/rng-uclass.c index 53108e1b31..3a8fb7d276 100644 --- a/drivers/rng/rng-uclass.c +++ b/drivers/rng/rng-uclass.c @@ -19,6 +19,26 @@ int dm_rng_read(struct udevice *dev, void *buffer, size_t size) return ops->read(dev, buffer, size); }

+int dm_rng_read_default(void *buffer, size_t size) +{

• struct udevice *rng;
• int ret;
• ret = uclass_get_device(UCLASS_RNG, 0, &rng);

This function will give you the first RNG device and not the first successfully probed RNG device.

We already have a weak function platform_get_rng_device() which allows a board to provide a different device. I think we should move platform_get_rng_device() to rng-uclass.c and use it here.

platform_get_rng_device should be re-implemented to provide the first successfully probed RNG device.

• if (ret) {

• pr_err("Can't get RNG device (%d)\n", ret);
  

• return ret;
  

• }
• ret = dm_rng_read(rng, buffer, size);

Here you are using a device which may not have been probed yet.

Best regards

Heinrich

• if (ret) {

• pr_err("Can't read from RNG device (%d)\n", ret);
  

• return ret;
  

• }
• return 0;

+}

• UCLASS_DRIVER(rng) = { .name = "rng", .id = UCLASS_RNG,

diff --git a/include/rng.h b/include/rng.h index 37af554363..5537daae88 100644 --- a/include/rng.h +++ b/include/rng.h @@ -20,6 +20,16 @@ struct udevice; */ int dm_rng_read(struct udevice *dev, void *buffer, size_t size);

+/**

• • dm_rng_read_default() - same as dm_rng_read(), except that caller
• • don't need to pass an argument with RNG udevice.
• • @buffer: input buffer to put the read random seed into
• • @size: number of bytes of random seed read
• • Return: 0 if OK, -ve on error
• */

+int dm_rng_read_default(void *buffer, size_t size);

• /**
  • struct dm_rng_ops - operations for the hwrng uclass