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 * 10) >> 5) /* quality: 10/32 */ 26 27 static DECLARE_WAIT_QUEUE_HEAD(rng_queue); 28 29 static int ath9k_rng_data_read(struct ath_softc *sc, u32 *buf, u32 buf_size) 30 { 31 int i, j; 32 u32 v1, v2, rng_last = sc->rng_last; 33 struct ath_hw *ah = sc->sc_ah; 34 35 ath9k_ps_wakeup(sc); 36 37 REG_RMW_FIELD(ah, AR_PHY_TEST, AR_PHY_TEST_BBB_OBS_SEL, 1); 38 REG_CLR_BIT(ah, AR_PHY_TEST, AR_PHY_TEST_RX_OBS_SEL_BIT5); 39 REG_RMW_FIELD(ah, AR_PHY_TEST_CTL_STATUS, AR_PHY_TEST_CTL_RX_OBS_SEL, 0); 40 41 for (i = 0, j = 0; i < buf_size; i++) { 42 v1 = REG_READ(ah, AR_PHY_TST_ADC) & 0xffff; 43 v2 = REG_READ(ah, AR_PHY_TST_ADC) & 0xffff; 44 45 /* wait for data ready */ 46 if (v1 && v2 && rng_last != v1 && v1 != v2 && v1 != 0xffff && 47 v2 != 0xffff) 48 buf[j++] = (v1 << 16) | v2; 49 50 rng_last = v2; 51 } 52 53 ath9k_ps_restore(sc); 54 55 sc->rng_last = rng_last; 56 57 return j << 2; 58 } 59 60 static u32 ath9k_rng_delay_get(u32 fail_stats) 61 { 62 u32 delay; 63 64 if (fail_stats < 100) 65 delay = 10; 66 else if (fail_stats < 105) 67 delay = 1000; 68 else 69 delay = 10000; 70 71 return delay; 72 } 73 74 static int ath9k_rng_kthread(void *data) 75 { 76 int bytes_read; 77 struct ath_softc *sc = data; 78 u32 *rng_buf; 79 u32 delay, fail_stats = 0; 80 81 rng_buf = kmalloc_array(ATH9K_RNG_BUF_SIZE, sizeof(u32), GFP_KERNEL); 82 if (!rng_buf) 83 goto out; 84 85 while (!kthread_should_stop()) { 86 bytes_read = ath9k_rng_data_read(sc, rng_buf, 87 ATH9K_RNG_BUF_SIZE); 88 if (unlikely(!bytes_read)) { 89 delay = ath9k_rng_delay_get(++fail_stats); 90 wait_event_interruptible_timeout(rng_queue, 91 kthread_should_stop(), 92 msecs_to_jiffies(delay)); 93 continue; 94 } 95 96 fail_stats = 0; 97 98 /* sleep until entropy bits under write_wakeup_threshold */ 99 add_hwgenerator_randomness((void *)rng_buf, bytes_read, 100 ATH9K_RNG_ENTROPY(bytes_read)); 101 } 102 103 kfree(rng_buf); 104 out: 105 sc->rng_task = NULL; 106 107 return 0; 108 } 109 110 void ath9k_rng_start(struct ath_softc *sc) 111 { 112 struct ath_hw *ah = sc->sc_ah; 113 114 if (sc->rng_task) 115 return; 116 117 if (!AR_SREV_9300_20_OR_LATER(ah)) 118 return; 119 120 sc->rng_task = kthread_run(ath9k_rng_kthread, sc, "ath9k-hwrng"); 121 if (IS_ERR(sc->rng_task)) 122 sc->rng_task = NULL; 123 } 124 125 void ath9k_rng_stop(struct ath_softc *sc) 126 { 127 if (sc->rng_task) { 128 kthread_stop(sc->rng_task); 129 sc->rng_task = NULL; 130 } 131 } 132