Re: [PATCH v5 6/9] cmd: rng: Add support for selecting RNG device

hi Heinrich,

On Mon, 14 Mar 2022 at 03:53, Simon Glass sjg@chromium.org wrote:

Hi Sughosh,

On Sun, 13 Mar 2022 at 08:49, Sughosh Ganu sughosh.ganu@linaro.org wrote:

...

The 'rng' u-boot command is used for printing a select number of random bytes on the console. Currently, the RNG device from which the random bytes are read is fixed. However, a platform can have multiple RNG devices, one example being qemu, which has a virtio RNG device and the RNG pseudo device through the TPM chip.

Extend the 'rng' command so that the user can provide the RNG device number from which the random bytes are to be read. This will be the device index under the RNG uclass.

Signed-off-by: Sughosh Ganu sughosh.ganu@linaro.org Tested-by: Heinrich Schuchardt xypron.glpk@gmx.de Reviewed-by: Ilias Apalodimas ilias.apalodimas@linaro.org

---

Changes since V4:

• Use uclass_get_device_by_seq API to get the RNG device as suggested by Simon

cmd/rng.c | 31 +++++++++++++++++++++++-------- 1 file changed, 23 insertions(+), 8 deletions(-)

Can you please pick this up, as this has been reviewed and is not related to the TPM RNG changes which are still under discussion. Thanks.

-sughosh

Reviewed-by: Simon Glass sjg@chromium.org

with the nit below fixed

...

diff --git a/cmd/rng.c b/cmd/rng.c index 1ad5a096c0..2ddf27545f 100644 --- a/cmd/rng.c +++ b/cmd/rng.c @@ -13,19 +13,34 @@

static int do_rng(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[]) {

•   size_t n = 0x40;
  

•   size_t n;
    struct udevice *dev;
    void *buf;
  

•   int devnum;
    int ret = CMD_RET_SUCCESS;
  
  

•   if (uclass_get_device(UCLASS_RNG, 0, &dev) || !dev) {
  

•   switch (argc) {
  

•   case 1:
  

•           devnum = 0;
  

•           n = 0x40;
  

•           break;
  

•   case 2:
  

•           devnum = hextoul(argv[1], NULL);
  

•           n = 0x40;
  

•           break;
  

•   case 3:
  

•           devnum = hextoul(argv[1], NULL);
  

•           n = hextoul(argv[2], NULL);
  

•           break;
  

•   default:
  

•           return CMD_RET_USAGE;
  

•   }
  

•   if (uclass_get_device_by_seq(UCLASS_RNG, devnum, &dev) || !dev) {
  

Please check the function comments: you can drop the '|| !dev' bit since it returns an error if no device is found.

...

            printf("No RNG device\n");
            return CMD_RET_FAILURE;
    }

•   if (argc >= 2)
  

•           n = hextoul(argv[1], NULL);
  

•   buf = malloc(n);
    if (!buf) {
            printf("Out of memory\n");
  

@@ -46,12 +61,12 @@ static int do_rng(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])

#ifdef CONFIG_SYS_LONGHELP static char rng_help_text[] =

•   "[n]\n"
  

•   "  - print n random bytes\n";
  

•   "[dev [n]]\n"
  

•   "  - print n random bytes read from dev\n";
  

#endif

U_BOOT_CMD(

•   rng, 2, 0, do_rng,
  

•   rng, 3, 0, do_rng,
    "print bytes from the hardware random number generator",
    rng_help_text
  

);

2.25.1

Regards, SImon