1 /* 2 * Copyright (c) 2015 Qualcomm Atheros, Inc. 3 * 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. 7 * 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. 15 */ 16 17 #include <linux/hw_random.h> 18 #include <linux/kthread.h> 19 20 #include "ath9k.h" 21 #include "hw.h" 22 #include "ar9003_phy.h" 23 24 #define ATH9K_RNG_BUF_SIZE 320 25 #define ATH9K_RNG_ENTROPY(x) (((x) * 8 * 320) >> 10) /* quality: 320/1024 */ 26 27 static int ath9k_rng_data_read(struct ath_softc *sc, u32 *buf, u32 buf_size) 28 { 29 int i, j; 30 u32 v1, v2, rng_last = sc->rng_last; 31 struct ath_hw *ah = sc->sc_ah; 32 33 ath9k_ps_wakeup(sc); 34 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); 38 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; 42 43 /* wait for data ready */ 44 if (v1 && v2 && rng_last != v1 && v1 != v2 && v1 != 0xffff && 45 v2 != 0xffff) 46 buf[j++] = (v1 << 16) | v2; 47 48 rng_last = v2; 49 } 50 51 ath9k_ps_restore(sc); 52 53 sc->rng_last = rng_last; 54 55 return j << 2; 56 } 57 58 static int ath9k_rng_kthread(void *data) 59 { 60 int bytes_read; 61 struct ath_softc *sc = data; 62 u32 *rng_buf; 63 64 rng_buf = kmalloc_array(ATH9K_RNG_BUF_SIZE, sizeof(u32), GFP_KERNEL); 65 if (!rng_buf) 66 goto out; 67 68 while (!kthread_should_stop()) { 69 bytes_read = ath9k_rng_data_read(sc, rng_buf, 70 ATH9K_RNG_BUF_SIZE); 71 if (unlikely(!bytes_read)) { 72 msleep_interruptible(10); 73 continue; 74 } 75 76 /* sleep until entropy bits under write_wakeup_threshold */ 77 add_hwgenerator_randomness((void *)rng_buf, bytes_read, 78 ATH9K_RNG_ENTROPY(bytes_read)); 79 } 80 81 kfree(rng_buf); 82 out: 83 sc->rng_task = NULL; 84 85 return 0; 86 } 87 88 void ath9k_rng_start(struct ath_softc *sc) 89 { 90 struct ath_hw *ah = sc->sc_ah; 91 92 if (sc->rng_task) 93 return; 94 95 if (!AR_SREV_9300_20_OR_LATER(ah)) 96 return; 97 98 sc->rng_task = kthread_run(ath9k_rng_kthread, sc, "ath9k-hwrng"); 99 if (IS_ERR(sc->rng_task)) 100 sc->rng_task = NULL; 101 } 102 103 void ath9k_rng_stop(struct ath_softc *sc) 104 { 105 if (sc->rng_task) 106 kthread_stop(sc->rng_task); 107 } 108