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 u32 ath9k_rng_delay_get(u32 fail_stats) 59 { 60 u32 delay; 61 62 if (fail_stats < 100) 63 delay = 10; 64 else if (fail_stats < 105) 65 delay = 1000; 66 else 67 delay = 10000; 68 69 return delay; 70 } 71 72 static int ath9k_rng_kthread(void *data) 73 { 74 int bytes_read; 75 struct ath_softc *sc = data; 76 u32 *rng_buf; 77 u32 delay, fail_stats = 0; 78 79 rng_buf = kmalloc_array(ATH9K_RNG_BUF_SIZE, sizeof(u32), GFP_KERNEL); 80 if (!rng_buf) 81 goto out; 82 83 while (!kthread_should_stop()) { 84 bytes_read = ath9k_rng_data_read(sc, rng_buf, 85 ATH9K_RNG_BUF_SIZE); 86 if (unlikely(!bytes_read)) { 87 delay = ath9k_rng_delay_get(++fail_stats); 88 msleep_interruptible(delay); 89 continue; 90 } 91 92 fail_stats = 0; 93 94 /* sleep until entropy bits under write_wakeup_threshold */ 95 add_hwgenerator_randomness((void *)rng_buf, bytes_read, 96 ATH9K_RNG_ENTROPY(bytes_read)); 97 } 98 99 kfree(rng_buf); 100 out: 101 sc->rng_task = NULL; 102 103 return 0; 104 } 105 106 void ath9k_rng_start(struct ath_softc *sc) 107 { 108 struct ath_hw *ah = sc->sc_ah; 109 110 if (sc->rng_task) 111 return; 112 113 if (!AR_SREV_9300_20_OR_LATER(ah)) 114 return; 115 116 sc->rng_task = kthread_run(ath9k_rng_kthread, sc, "ath9k-hwrng"); 117 if (IS_ERR(sc->rng_task)) 118 sc->rng_task = NULL; 119 } 120 121 void ath9k_rng_stop(struct ath_softc *sc) 122 { 123 if (sc->rng_task) 124 kthread_stop(sc->rng_task); 125 } 126