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hwrng: atmel - add wait for ready support on read

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Add wait for ready support on read.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Claudiu Beznea 2022-02-21 09:59:22 +02:00 committed by Herbert Xu
parent 0a2a464f86
commit 0934683dd1
1 changed files with 30 additions and 13 deletions
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43
drivers/char/hw_random/atmel-rng.c
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@ -13,6 +13,7 @@
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/hw_random.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
@ -20,6 +21,7 @@
#define TRNG_CR 0x00
#define TRNG_MR 0x04
#define TRNG_ISR 0x1c
#define TRNG_ISR_DATRDY BIT(0)
#define TRNG_ODATA 0x50
#define TRNG_KEY 0x524e4700 /* RNG */
@ -36,25 +38,40 @@ struct atmel_trng {
struct hwrng rng;
};
static bool atmel_trng_wait_ready(struct atmel_trng *trng, bool wait)
{
int ready;
ready = readl(trng->base + TRNG_ISR) & TRNG_ISR_DATRDY;
if (!ready && wait)
readl_poll_timeout(trng->base + TRNG_ISR, ready,
ready & TRNG_ISR_DATRDY, 1000, 20000);
return !!ready;
}
static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
bool wait)
{
struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);
u32 *data = buf;
int ret;
/* data ready? */
if (readl(trng->base + TRNG_ISR) & 1) {
*data = readl(trng->base + TRNG_ODATA);
/*
ensure data ready is only set again AFTER the next data
word is ready in case it got set between checking ISR
and reading ODATA, so we don't risk re-reading the
same word
*/
readl(trng->base + TRNG_ISR);
return 4;
} else
return 0;
ret = atmel_trng_wait_ready(trng, wait);
if (!ret)
goto out;
*data = readl(trng->base + TRNG_ODATA);
/*
* ensure data ready is only set again AFTER the next data word is ready
* in case it got set between checking ISR and reading ODATA, so we
* don't risk re-reading the same word
*/
readl(trng->base + TRNG_ISR);
ret = 4;
out:
return ret;
}
static void atmel_trng_enable(struct atmel_trng *trng)