128 lines
3.0 KiB
C
128 lines
3.0 KiB
C
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/*
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* Copyright (c) 2015 Qualcomm Atheros, Inc.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <linux/hw_random.h>
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#include <linux/kthread.h>
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#include "ath9k.h"
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#include "hw.h"
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#include "ar9003_phy.h"
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#define ATH9K_RNG_BUF_SIZE 320
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#define ATH9K_RNG_ENTROPY(x) (((x) * 8 * 320) >> 10) /* quality: 320/1024 */
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static int ath9k_rng_data_read(struct ath_softc *sc, u32 *buf, u32 buf_size)
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{
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int i, j;
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u32 v1, v2, rng_last = sc->rng_last;
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struct ath_hw *ah = sc->sc_ah;
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ath9k_ps_wakeup(sc);
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REG_RMW_FIELD(ah, AR_PHY_TEST, AR_PHY_TEST_BBB_OBS_SEL, 1);
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REG_CLR_BIT(ah, AR_PHY_TEST, AR_PHY_TEST_RX_OBS_SEL_BIT5);
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REG_RMW_FIELD(ah, AR_PHY_TEST_CTL_STATUS, AR_PHY_TEST_CTL_RX_OBS_SEL, 0);
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for (i = 0, j = 0; i < buf_size; i++) {
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v1 = REG_READ(ah, AR_PHY_TST_ADC) & 0xffff;
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v2 = REG_READ(ah, AR_PHY_TST_ADC) & 0xffff;
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/* wait for data ready */
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if (v1 && v2 && rng_last != v1 && v1 != v2 && v1 != 0xffff &&
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v2 != 0xffff)
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buf[j++] = (v1 << 16) | v2;
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rng_last = v2;
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}
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ath9k_ps_restore(sc);
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sc->rng_last = rng_last;
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return j << 2;
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}
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static u32 ath9k_rng_delay_get(u32 fail_stats)
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{
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u32 delay;
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if (fail_stats < 100)
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delay = 10;
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else if (fail_stats < 105)
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delay = 1000;
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else
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delay = 10000;
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return delay;
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}
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static int ath9k_rng_kthread(void *data)
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{
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int bytes_read;
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struct ath_softc *sc = data;
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u32 *rng_buf;
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u32 delay, fail_stats = 0;
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rng_buf = kmalloc_array(ATH9K_RNG_BUF_SIZE, sizeof(u32), GFP_KERNEL);
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if (!rng_buf)
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goto out;
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while (!kthread_should_stop()) {
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bytes_read = ath9k_rng_data_read(sc, rng_buf,
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ATH9K_RNG_BUF_SIZE);
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if (unlikely(!bytes_read)) {
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delay = ath9k_rng_delay_get(++fail_stats);
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msleep_interruptible(delay);
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continue;
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}
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fail_stats = 0;
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/* sleep until entropy bits under write_wakeup_threshold */
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add_hwgenerator_randomness((void *)rng_buf, bytes_read,
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ATH9K_RNG_ENTROPY(bytes_read));
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}
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kfree(rng_buf);
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out:
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sc->rng_task = NULL;
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return 0;
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}
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void ath9k_rng_start(struct ath_softc *sc)
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{
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struct ath_hw *ah = sc->sc_ah;
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if (sc->rng_task)
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return;
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if (!AR_SREV_9300_20_OR_LATER(ah))
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return;
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sc->rng_task = kthread_run(ath9k_rng_kthread, sc, "ath9k-hwrng");
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if (IS_ERR(sc->rng_task))
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sc->rng_task = NULL;
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}
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void ath9k_rng_stop(struct ath_softc *sc)
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{
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if (sc->rng_task) {
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kthread_stop(sc->rng_task);
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sc->rng_task = NULL;
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}
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}
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