2 * Copyright (c) 2015 Qualcomm Atheros, Inc.
4 * Permission to use, copy, modify, and/or distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 #include <linux/hw_random.h>
18 #include <linux/kthread.h>
22 #include "ar9003_phy.h"
24 #define ATH9K_RNG_BUF_SIZE 320
25 #define ATH9K_RNG_ENTROPY(x) (((x) * 8 * 320) >> 10) /* quality: 320/1024 */
27 static int ath9k_rng_data_read(struct ath_softc *sc, u32 *buf, u32 buf_size)
30 u32 v1, v2, rng_last = sc->rng_last;
31 struct ath_hw *ah = sc->sc_ah;
35 REG_RMW_FIELD(ah, AR_PHY_TEST, AR_PHY_TEST_BBB_OBS_SEL, 1);
36 REG_CLR_BIT(ah, AR_PHY_TEST, AR_PHY_TEST_RX_OBS_SEL_BIT5);
37 REG_RMW_FIELD(ah, AR_PHY_TEST_CTL_STATUS, AR_PHY_TEST_CTL_RX_OBS_SEL, 0);
39 for (i = 0, j = 0; i < buf_size; i++) {
40 v1 = REG_READ(ah, AR_PHY_TST_ADC) & 0xffff;
41 v2 = REG_READ(ah, AR_PHY_TST_ADC) & 0xffff;
43 /* wait for data ready */
44 if (v1 && v2 && rng_last != v1 && v1 != v2 && v1 != 0xffff &&
46 buf[j++] = (v1 << 16) | v2;
53 sc->rng_last = rng_last;
58 static u32 ath9k_rng_delay_get(u32 fail_stats)
64 else if (fail_stats < 105)
72 static int ath9k_rng_kthread(void *data)
75 struct ath_softc *sc = data;
77 u32 delay, fail_stats = 0;
79 rng_buf = kmalloc_array(ATH9K_RNG_BUF_SIZE, sizeof(u32), GFP_KERNEL);
83 while (!kthread_should_stop()) {
84 bytes_read = ath9k_rng_data_read(sc, rng_buf,
86 if (unlikely(!bytes_read)) {
87 delay = ath9k_rng_delay_get(++fail_stats);
88 msleep_interruptible(delay);
94 /* sleep until entropy bits under write_wakeup_threshold */
95 add_hwgenerator_randomness((void *)rng_buf, bytes_read,
96 ATH9K_RNG_ENTROPY(bytes_read));
106 void ath9k_rng_start(struct ath_softc *sc)
108 struct ath_hw *ah = sc->sc_ah;
113 if (!AR_SREV_9300_20_OR_LATER(ah))
116 sc->rng_task = kthread_run(ath9k_rng_kthread, sc, "ath9k-hwrng");
117 if (IS_ERR(sc->rng_task))
121 void ath9k_rng_stop(struct ath_softc *sc)
124 kthread_stop(sc->rng_task);