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hwrng: imx-rngc - use automatic seeding

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The rngc requires a new seed for its prng after generating 2^20 160-bit
words of random data. At the moment, we seed the prng only once during
initalisation.

Set the rngc to auto seed mode so that it kicks off the internal
reseeding operation when a new seed is required.

Keep the manual calculation of the initial seed when the device is
probed and switch to automatic seeding afterwards.

Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Martin Kaiser 2020-03-05 21:58:21 +01:00 committed by Herbert Xu
parent 47a1f8e8b3
commit 3acd9ea933
1 changed files with 14 additions and 2 deletions
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16
drivers/char/hw_random/imx-rngc.c
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@ -31,6 +31,7 @@
#define RNGC_CTRL_MASK_ERROR 0x00000040
#define RNGC_CTRL_MASK_DONE 0x00000020
#define RNGC_CTRL_AUTO_SEED 0x00000010
#define RNGC_STATUS_ERROR 0x00010000
#define RNGC_STATUS_FIFO_LEVEL_MASK 0x00000f00
@ -167,7 +168,7 @@ static irqreturn_t imx_rngc_irq(int irq, void *priv)
static int imx_rngc_init(struct hwrng *rng)
{
struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng);
u32 cmd;
u32 cmd, ctrl;
int ret;
/* clear error */
@ -192,7 +193,18 @@ static int imx_rngc_init(struct hwrng *rng)
} while (rngc->err_reg == RNGC_ERROR_STATUS_STAT_ERR);
return rngc->err_reg ? -EIO : 0;
if (rngc->err_reg)
return -EIO;
/*
* enable automatic seeding, the rngc creates a new seed automatically
* after serving 2^20 random 160-bit words
*/
ctrl = readl(rngc->base + RNGC_CONTROL);
ctrl |= RNGC_CTRL_AUTO_SEED;
writel(ctrl, rngc->base + RNGC_CONTROL);
return 0;
}
static int imx_rngc_probe(struct platform_device *pdev)