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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"
#define ATH9K_RNG_BUF_SIZE 320
#define ATH9K_RNG_ENTROPY(x) (((x) * 8 * 10) >> 5) /* quality: 10/32 */
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, AR_PHY_TEST_BBB_OBS_SEL, 1);
REG_CLR_BIT(ah, AR_PHY_TEST, AR_PHY_TEST_RX_OBS_SEL_BIT5);
REG_RMW_FIELD(ah, AR_PHY_TEST_CTL_STATUS, 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_kthread(void *data)
{
int bytes_read;
struct ath_softc *sc = data;
u32 *rng_buf;
u32 delay, fail_stats = 0;
rng_buf = kmalloc_array(ATH9K_RNG_BUF_SIZE, sizeof(u32), GFP_KERNEL);
if (!rng_buf)
goto out;
while (!kthread_should_stop()) {
bytes_read = ath9k_rng_data_read(sc, rng_buf,
ATH9K_RNG_BUF_SIZE);
if (unlikely(!bytes_read)) {
delay = ath9k_rng_delay_get(++fail_stats);
msleep_interruptible(delay);
continue;
}
fail_stats = 0;
/* sleep until entropy bits under write_wakeup_threshold */
add_hwgenerator_randomness((void *)rng_buf, bytes_read,
ATH9K_RNG_ENTROPY(bytes_read));
}
kfree(rng_buf);
out:
sc->rng_task = NULL;
return 0;
}
void ath9k_rng_start(struct ath_softc *sc)
{
struct ath_hw *ah = sc->sc_ah;
if (sc->rng_task)
return;
if (!AR_SREV_9300_20_OR_LATER(ah))
return;
sc->rng_task = kthread_run(ath9k_rng_kthread, sc, "ath9k-hwrng");
if (IS_ERR(sc->rng_task))
sc->rng_task = NULL;
}
void ath9k_rng_stop(struct ath_softc *sc)
{
if (sc->rng_task)
kthread_stop(sc->rng_task);
}
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