On Fri, 27 Dec 2019 at 12:39, Heinrich Schuchardt xypron.glpk@gmx.de wrote:
On 12/26/19 6:25 PM, Sughosh Ganu wrote:
Add a uclass for reading a random number seed from a random number generator device.
Signed-off-by: Sughosh Ganu sughosh.ganu@linaro.org Reviewed-by: Patrice Chotard patrice.chotard@st.com
Changes since V4:
Use Sphinx syntax for Return value in the read function
Return number of bytes read on a successful read, and a -ve value on error.
drivers/Kconfig | 2 ++ drivers/Makefile | 1 + drivers/rng/Kconfig | 7 +++++++ drivers/rng/Makefile | 6 ++++++ drivers/rng/rng-uclass.c | 23 +++++++++++++++++++++++ include/dm/uclass-id.h | 1 + include/rng.h | 33 +++++++++++++++++++++++++++++++++ 7 files changed, 73 insertions(+) create mode 100644 drivers/rng/Kconfig create mode 100644 drivers/rng/Makefile create mode 100644 drivers/rng/rng-uclass.c create mode 100644 include/rng.h
<snip>
diff --git a/include/rng.h b/include/rng.h new file mode 100644 index 0000000..9a71e81 --- /dev/null +++ b/include/rng.h @@ -0,0 +1,33 @@ +// SPDX-License-Identifier: GPL-2.0+ +/*
- Copyright (c) 2019, Linaro Limited
- */
+#if !defined _RNG_H_ +#define _RNG_H_
+#include <dm.h>
+/**
- dm_rng_read() - read a random number seed from the rng device
- @buffer: input buffer to put the read random seed into
- @size: number of bytes of random seed read
- Return: number of bytes read if OK, -ve on error
- */
+int dm_rng_read(struct udevice *dev, void *buffer, size_t size);
+/* struct dm_rng_ops - Operations for the hwrng uclass */ +struct dm_rng_ops {
/*** @read() - read a random number seed** @data: input buffer to read the random seed* @max: total number of bytes to read** Return: number of bytes read if OK, -ve on error*/int (*read)(struct udevice *dev, void *data, size_t max);With this interface definition the caller has to check the return value and to call read() again and again until all bytes needed are requested. The EFI_RNG_PROTOCOL will not be the only consumer of the hardware RNG so we will have to rewrite that logic in multiple places. In U-Boot we are very tight on the binary size. So I would really appreciate to avoid such code duplication by making it the drivers duty to return exactly the number of bytes requested.
Ok. I had tested the code with the loop inside the virtio driver yesterday, and with more than max-bytes requested, the system would freeze for a pretty longish bit before returning the data. I mistook this for a system hang, which is why I moved the loop out of the driver. Testing again, after putting the loop inside the driver, i see that this works. I will send an updated version with the loop inside the driver as you ask. The read function will return 0 on a successful read, and a -ve error on failure.
-sughosh