Revert "ath9k: export HW random number generator"

This reverts commit 6301566e. Oleksij Rempel
noticed that the randomness doesn't look to be good enough and Stephan Mueller
commented:

"I would say that the discussed RNG does not seem fit for hooking it up with the
hwrandom framework."

http://lkml.kernel.org/g/3945775.m5HblJPgiO@tauon.atsec.com

So let's the revert the patch until we are sure that we can trust this random
generator.
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ath/ath9k/Kconfig

@@ -176,10 +176,3 @@ config ATH9K_HTC_DEBUGFS
 	depends on ATH9K_HTC && DEBUG_FS
 	---help---
 	  Say Y, if you need access to ath9k_htc's statistics.
-
-config ATH9K_HWRNG
-	bool "Random number generator support"
-	depends on ATH9K && (HW_RANDOM = y || HW_RANDOM = ATH9K)
-	default y
-	---help---
-	  Provides a hardware random number generator to the kernel.

drivers/net/wireless/ath/ath9k/Makefile

@@ -15,7 +15,6 @@ ath9k-$(CONFIG_ATH9K_DFS_DEBUGFS) += dfs_debug.o
 ath9k-$(CONFIG_ATH9K_DFS_CERTIFIED) += dfs.o
 ath9k-$(CONFIG_ATH9K_TX99) += tx99.o
 ath9k-$(CONFIG_ATH9K_WOW) += wow.o
-ath9k-$(CONFIG_ATH9K_HWRNG) += rng.o
 
 ath9k-$(CONFIG_ATH9K_DEBUGFS) += debug.o
 

drivers/net/wireless/ath/ath9k/ath9k.h

@@ -23,7 +23,6 @@
 #include <linux/leds.h>
 #include <linux/completion.h>
 #include <linux/time.h>
-#include <linux/hw_random.h>
 
 #include "common.h"
 #include "debug.h"
@@ -1042,12 +1041,6 @@ struct ath_softc {
 	u32 wow_intr_before_sleep;
 	bool force_wow;
 #endif
-
-#ifdef CONFIG_ATH9K_HWRNG
-	struct hwrng rng;
-	bool rng_initialized;
-	u32 rng_last;
-#endif
 };
 
 /********/
@@ -1070,22 +1063,6 @@ static inline int ath9k_tx99_send(struct ath_softc *sc,
 }
 #endif /* CONFIG_ATH9K_TX99 */
 
-/***************************/
-/* Random Number Generator */
-/***************************/
-#ifdef CONFIG_ATH9K_HWRNG
-void ath9k_rng_register(struct ath_softc *sc);
-void ath9k_rng_unregister(struct ath_softc *sc);
-#else
-static inline void ath9k_rng_register(struct ath_softc *sc)
-{
-}
-
-static inline void ath9k_rng_unregister(struct ath_softc *sc)
-{
-}
-#endif
-
 static inline void ath_read_cachesize(struct ath_common *common, int *csz)
 {
 	common->bus_ops->read_cachesize(common, csz);

drivers/net/wireless/ath/ath9k/main.c

@@ -739,8 +739,6 @@ static int ath9k_start(struct ieee80211_hw *hw)
 
 	ath9k_ps_restore(sc);
 
-	ath9k_rng_register(sc);
-
 	return 0;
 }
 
@@ -830,8 +828,6 @@ static void ath9k_stop(struct ieee80211_hw *hw)
 
 	ath9k_deinit_channel_context(sc);
 
-	ath9k_rng_unregister(sc);
-
 	mutex_lock(&sc->mutex);
 
 	ath_cancel_work(sc);

drivers/net/wireless/ath/ath9k/rng.c

-/*
- * Copyright (c) 2015 Qualcomm Atheros, Inc.
- *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- */
-
-#include "ath9k.h"
-#include "hw.h"
-#include "ar9003_phy.h"
-
-static int ath9k_rng_data_read(struct hwrng *rng, u32 *data)
-{
-	u32 v1, v2;
-	struct ath_softc *sc = (struct ath_softc *)rng->priv;
-	struct ath_hw *ah = sc->sc_ah;
-
-	ath9k_ps_wakeup(sc);
-
-	REG_RMW_FIELD(ah, AR_PHY_TEST, AR_PHY_TEST_BBB_OBS_SEL, 5);
-	REG_CLR_BIT(ah, AR_PHY_TEST, AR_PHY_TEST_RX_OBS_SEL_BIT5);
-	REG_RMW_FIELD(ah, AR_PHY_TEST_CTL_STATUS, AR_PHY_TEST_CTL_RX_OBS_SEL, 0);
-
-	v1 = REG_READ(ah, AR_PHY_TST_ADC);
-	v2 = REG_READ(ah, AR_PHY_TST_ADC);
-
-	ath9k_ps_restore(sc);
-
-	/* wait for data ready */
-	if (v1 && v2 && sc->rng_last != v1 && v1 != v2) {
-		*data = (v1 & 0xffff) | (v2 << 16);
-		sc->rng_last = v2;
-
-		return sizeof(u32);
-	}
-
-	sc->rng_last = v2;
-
-	return 0;
-}
-
-void ath9k_rng_register(struct ath_softc *sc)
-{
-	struct ath_hw *ah = sc->sc_ah;
-
-	if (WARN_ON(sc->rng_initialized))
-		return;
-
-	if (!AR_SREV_9300_20_OR_LATER(ah))
-		return;
-
-	sc->rng.name = "ath9k";
-	sc->rng.data_read = ath9k_rng_data_read;
-	sc->rng.priv = (unsigned long)sc;
-
-	if (!hwrng_register(&sc->rng))
-		sc->rng_initialized = true;
-}
-
-void ath9k_rng_unregister(struct ath_softc *sc)
-{
-	if (sc->rng_initialized) {
-		hwrng_unregister(&sc->rng);
-		sc->rng_initialized = false;
-	}
-}