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/*
* Copyright (c) 2015 Qualcomm Atheros, Inc.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <linux/hw_random.h>
#include <linux/kthread.h>
#include "ath9k.h"
#include "hw.h"
#include "ar9003_phy.h"
static int ath9k_rng_data_read(struct ath_softc *sc, u32 *buf, u32 buf_size)
{
int i, j;
u32 v1, v2, rng_last = sc->rng_last;
struct ath_hw *ah = sc->sc_ah;
ath9k_ps_wakeup(sc);
REG_RMW_FIELD(ah, AR_PHY_TEST(ah), AR_PHY_TEST_BBB_OBS_SEL, 1);
REG_CLR_BIT(ah, AR_PHY_TEST(ah), AR_PHY_TEST_RX_OBS_SEL_BIT5);
REG_RMW_FIELD(ah, AR_PHY_TEST_CTL_STATUS(ah), AR_PHY_TEST_CTL_RX_OBS_SEL, 0);
for (i = 0, j = 0; i < buf_size; i++) {
v1 = REG_READ(ah, AR_PHY_TST_ADC) & 0xffff;
v2 = REG_READ(ah, AR_PHY_TST_ADC) & 0xffff;
/* wait for data ready */
if (v1 && v2 && rng_last != v1 && v1 != v2 && v1 != 0xffff &&
v2 != 0xffff)
buf[j++] = (v1 << 16) | v2;
rng_last = v2;
}
ath9k_ps_restore(sc);
sc->rng_last = rng_last;
return j << 2;
}
static u32 ath9k_rng_delay_get(u32 fail_stats)
{
u32 delay;
if (fail_stats < 100)
delay = 10;
else if (fail_stats < 105)
delay = 1000;
else
delay = 10000;
return delay;
}
static int ath9k_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
{
struct ath_softc *sc = container_of(rng, struct ath_softc, rng_ops);
u32 fail_stats = 0, word;
int bytes_read = 0;
for (;;) {
if (max & ~3UL)
bytes_read = ath9k_rng_data_read(sc, buf, max >> 2);
if ((max & 3UL) && ath9k_rng_data_read(sc, &word, 1)) {
memcpy(buf + bytes_read, &word, max & 3UL);
bytes_read += max & 3UL;
memzero_explicit(&word, sizeof(word));
}
if (!wait || !max || likely(bytes_read) || fail_stats > 110)
break;
if (hwrng_msleep(rng, ath9k_rng_delay_get(++fail_stats)))
break;
}
if (wait && !bytes_read && max)
bytes_read = -EIO;
return bytes_read;
}
void ath9k_rng_start(struct ath_softc *sc)
{
static atomic_t serial = ATOMIC_INIT(0);
struct ath_hw *ah = sc->sc_ah;
if (sc->rng_ops.read)
return;
if (!AR_SREV_9300_20_OR_LATER(ah))
return;
snprintf(sc->rng_name, sizeof(sc->rng_name), "ath9k_%u",
(atomic_inc_return(&serial) - 1) & U16_MAX);
sc->rng_ops.name = sc->rng_name;
sc->rng_ops.read = ath9k_rng_read;
sc->rng_ops.quality = 320;
if (devm_hwrng_register(sc->dev, &sc->rng_ops))
sc->rng_ops.read = NULL;
}
void ath9k_rng_stop(struct ath_softc *sc)
{
if (sc->rng_ops.read) {
devm_hwrng_unregister(sc->dev, &sc->rng_ops);
sc->rng_ops.read = NULL;
}
}
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