ath9k: use hw_random API instead of directly dumping into random.c

Hardware random number generators are supposed to use the hw_random
framework. This commit turns ath9k's kthread-based design into a proper
hw_random driver.

Cc: Toke Høiland-Jørgensen <toke@redhat.com>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: Rui Salvaterra <rsalvaterra@gmail.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Tested-by: Rui Salvaterra <rsalvaterra@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220216113323.53332-1-Jason@zx2c4.com

diff --git a/drivers/net/wireless/ath/ath9k/ath9k.h b/drivers/net/wireless/ath/ath9k/ath9k.h
index ef6f5ea06c1f53d2bd3b118f43e7444cf0090dec..3ccf8cfc6b6338f16624a731d943007318b9cf95 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -1071,8 +1071,9 @@ struct ath_softc {
 #endif
 
 #ifdef CONFIG_ATH9K_HWRNG
+       struct hwrng rng_ops;
        u32 rng_last;
-       struct task_struct *rng_task;
+       char rng_name[sizeof("ath9k_65535")];
 #endif
 };
 

diff --git a/drivers/net/wireless/ath/ath9k/rng.c b/drivers/net/wireless/ath/ath9k/rng.c
index f9d3d6eedd3cd994d8b9b2e7fbcdf0a13c8cdbab..cb5414265a9b53577f33c02edbb3a935f0321921 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/rng.c
+++ b/drivers/net/wireless/ath/ath9k/rng.c
@@ -21,11 +21,6 @@
 #include "hw.h"
 #include "ar9003_phy.h"
 
-#define ATH9K_RNG_BUF_SIZE     320
-#define ATH9K_RNG_ENTROPY(x)   (((x) * 8 * 10) >> 5) /* quality: 10/32 */
-
-static DECLARE_WAIT_QUEUE_HEAD(rng_queue);
-
 static int ath9k_rng_data_read(struct ath_softc *sc, u32 *buf, u32 buf_size)
 {
        int i, j;
@@ -71,61 +66,56 @@ static u32 ath9k_rng_delay_get(u32 fail_stats)
        return delay;
 }
 
-static int ath9k_rng_kthread(void *data)
+static int ath9k_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
 {
-       int bytes_read;
-       struct ath_softc *sc = data;
-       u32 *rng_buf;
-       u32 delay, fail_stats = 0;
-
-       rng_buf = kmalloc_array(ATH9K_RNG_BUF_SIZE, sizeof(u32), GFP_KERNEL);
-       if (!rng_buf)
-               goto out;
-
-       while (!kthread_should_stop()) {
-               bytes_read = ath9k_rng_data_read(sc, rng_buf,
-                                                ATH9K_RNG_BUF_SIZE);
-               if (unlikely(!bytes_read)) {
-                       delay = ath9k_rng_delay_get(++fail_stats);
-                       wait_event_interruptible_timeout(rng_queue,
-                                                        kthread_should_stop(),
-                                                        msecs_to_jiffies(delay));
-                       continue;
+       struct ath_softc *sc = container_of(rng, struct ath_softc, rng_ops);
+       u32 fail_stats = 0, word;
+       int bytes_read = 0;
+
+       for (;;) {
+               if (max & ~3UL)
+                       bytes_read = ath9k_rng_data_read(sc, buf, max >> 2);
+               if ((max & 3UL) && ath9k_rng_data_read(sc, &word, 1)) {
+                       memcpy(buf + bytes_read, &word, max & 3UL);
+                       bytes_read += max & 3UL;
+                       memzero_explicit(&word, sizeof(word));
                }
+               if (!wait || !max || likely(bytes_read) || fail_stats > 110)
+                       break;
 
-               fail_stats = 0;
-
-               /* sleep until entropy bits under write_wakeup_threshold */
-               add_hwgenerator_randomness((void *)rng_buf, bytes_read,
-                                          ATH9K_RNG_ENTROPY(bytes_read));
+               msleep_interruptible(ath9k_rng_delay_get(++fail_stats));
        }
 
-       kfree(rng_buf);
-out:
-       sc->rng_task = NULL;
-
-       return 0;
+       if (wait && !bytes_read && max)
+               bytes_read = -EIO;
+       return bytes_read;
 }
 
 void ath9k_rng_start(struct ath_softc *sc)
 {
+       static atomic_t serial = ATOMIC_INIT(0);
        struct ath_hw *ah = sc->sc_ah;
 
-       if (sc->rng_task)
+       if (sc->rng_ops.read)
                return;
 
        if (!AR_SREV_9300_20_OR_LATER(ah))
                return;
 
-       sc->rng_task = kthread_run(ath9k_rng_kthread, sc, "ath9k-hwrng");
-       if (IS_ERR(sc->rng_task))
-               sc->rng_task = NULL;
+       snprintf(sc->rng_name, sizeof(sc->rng_name), "ath9k_%u",
+                (atomic_inc_return(&serial) - 1) & U16_MAX);
+       sc->rng_ops.name = sc->rng_name;
+       sc->rng_ops.read = ath9k_rng_read;
+       sc->rng_ops.quality = 320;
+
+       if (devm_hwrng_register(sc->dev, &sc->rng_ops))
+               sc->rng_ops.read = NULL;
 }
 
 void ath9k_rng_stop(struct ath_softc *sc)
 {
-       if (sc->rng_task) {
-               kthread_stop(sc->rng_task);
-               sc->rng_task = NULL;
+       if (sc->rng_ops.read) {
+               devm_hwrng_unregister(sc->dev, &sc->rng_ops);
+               sc->rng_ops.read = NULL;
        }
 }