[PATCH 2/4] crypto: xilinx-trng - Fix return value of xtrng_hwrng_trng_read()

[Eric Biggers]

Implementations of hwrng::read are expected to return the number of
bytes generated.  Update xtrng_hwrng_trng_read() to match that.

Fixes: 8979744aca80 ("crypto: xilinx - Add TRNG driver for Versal")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
 drivers/crypto/xilinx/xilinx-trng.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/crypto/xilinx/xilinx-trng.c b/drivers/crypto/xilinx/xilinx-trng.c
index a35643baa489..a30b0b3b3685 100644
--- a/drivers/crypto/xilinx/xilinx-trng.c
+++ b/drivers/crypto/xilinx/xilinx-trng.c
@@ -237,22 +237,25 @@ static int xtrng_random_bytes_generate(struct xilinx_rng *rng, u8 *rand_buf_ptr,
 
 static int xtrng_hwrng_trng_read(struct hwrng *hwrng, void *data, size_t max, bool wait)
 {
 	u8 buf[TRNG_SEC_STRENGTH_BYTES];
 	struct xilinx_rng *rng;
-	int ret = -EINVAL, i = 0;
+	int ret = 0, i = 0;
 
 	rng = container_of(hwrng, struct xilinx_rng, trng);
 	while (i < max) {
 		ret = xtrng_random_bytes_generate(rng, buf, TRNG_SEC_STRENGTH_BYTES, wait);
-		if (ret < 0)
+		if (ret < 0) {
+			if (i == 0)
+				return ret;
 			break;
+		}
 
 		memcpy(data + i, buf, min_t(int, ret, (max - i)));
 		i += min_t(int, ret, (max - i));
 	}
-	return ret;
+	return i;
 }
 
 static int xtrng_hwrng_register(struct hwrng *trng)
 {
 	int ret;
-- 
2.54.0