Re: [PATCH v5 1/8] dm: rng: Add random number generator(rng) uclass

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

diff --git a/drivers/Kconfig b/drivers/Kconfig index 9d99ce0..e34a227 100644 --- a/drivers/Kconfig +++ b/drivers/Kconfig @@ -90,6 +90,8 @@ source "drivers/remoteproc/Kconfig"

source "drivers/reset/Kconfig"

+source "drivers/rng/Kconfig"

• source "drivers/rtc/Kconfig"

  source "drivers/scsi/Kconfig"

diff --git a/drivers/Makefile b/drivers/Makefile index e977f19..6c619b1 100644 --- a/drivers/Makefile +++ b/drivers/Makefile @@ -115,4 +115,5 @@ obj-$(CONFIG_W1_EEPROM) += w1-eeprom/

obj-$(CONFIG_MACH_PIC32) += ddr/microchip/ obj-$(CONFIG_DM_HWSPINLOCK) += hwspinlock/ +obj-$(CONFIG_DM_RNG) += rng/ endif diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig new file mode 100644 index 0000000..dd44cc0 --- /dev/null +++ b/drivers/rng/Kconfig @@ -0,0 +1,7 @@ +config DM_RNG

• bool "Driver support for Random Number Generator devices"
• depends on DM
• help

•  Enable driver model for random number generator(rng) devices.
  

•  This interface is used to initialise the rng device and to
  

•  read the random seed from the device.
  

diff --git a/drivers/rng/Makefile b/drivers/rng/Makefile new file mode 100644 index 0000000..311705b --- /dev/null +++ b/drivers/rng/Makefile @@ -0,0 +1,6 @@ +# SPDX-License-Identifier: GPL-2.0+ +# +# Copyright (c) 2019, Linaro Limited +#

+obj-$(CONFIG_DM_RNG) += rng-uclass.o diff --git a/drivers/rng/rng-uclass.c b/drivers/rng/rng-uclass.c new file mode 100644 index 0000000..b6af3b8 --- /dev/null +++ b/drivers/rng/rng-uclass.c @@ -0,0 +1,23 @@ +// SPDX-License-Identifier: GPL-2.0+ +/*

• • Copyright (c) 2019, Linaro Limited
• */

+#include <common.h> +#include <dm.h> +#include <rng.h>

+int dm_rng_read(struct udevice *dev, void *buffer, size_t size) +{

• const struct dm_rng_ops *ops = device_get_ops(dev);
• if (!ops->read)

• return -ENOSYS;
  

• return ops->read(dev, buffer, size);

+}

+UCLASS_DRIVER(rng) = {

• .name = "rng",
• .id = UCLASS_RNG,

+}; diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h index 0c563d8..192202d 100644 --- a/include/dm/uclass-id.h +++ b/include/dm/uclass-id.h @@ -86,6 +86,7 @@ enum uclass_id { UCLASS_REGULATOR, /* Regulator device */ UCLASS_REMOTEPROC, /* Remote Processor device */ UCLASS_RESET, /* Reset controller device */

• UCLASS_RNG, /* Random Number Generator */ UCLASS_RTC, /* Real time clock device */ UCLASS_SCSI, /* SCSI device */ UCLASS_SERIAL, /* Serial UART */

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.

Best regards

Heinrich

+};

+#endi.f /* _RNG_H_ */