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Commit 00044f17 authored by Christian Lamparter's avatar Christian Lamparter Committed by John W. Linville
Browse files

carl9170: export HW random number generator 



All AR9170 hardware have a 16-Bit random number generator.
The documentation claims the values are suitable for
"security keys".

The "throughput" is around 320Kibit/s. It's slow, but it
does work without introducing any special offload
firmware commands.

Signed-off-by: default avatarChristian Lamparter <chunkeey@googlemail.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent acf17712

drivers/net/wireless/ath/carl9170/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -39,3 +39,17 @@ config CARL9170_WPC 
	bool

	depends on CARL9170 && (INPUT = y || INPUT = CARL9170)

	default y



config CARL9170_HWRNG

        bool "Random number generator"

        depends on CARL9170 && (HW_RANDOM = y || HW_RANDOM = CARL9170)

        default n

	help

	  Provides a hardware random number generator to the kernel.



	  SECURITY WARNING: It's relatively easy to eavesdrop all

	  generated random numbers from the transport stream with

	  usbmon [software] or special usb sniffer hardware.



	  Say N, unless your setup[i.e.: embedded system] has no

	  other rng source and you can afford to take the risk.

drivers/net/wireless/ath/carl9170/carl9170.h

+12 −0
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ 
#include <linux/firmware.h>

#include <linux/completion.h>

#include <linux/spinlock.h>

#include <linux/hw_random.h>

#include <net/cfg80211.h>

#include <net/mac80211.h>

#include <linux/usb.h>
@@ -449,6 +450,17 @@ struct ar9170 { 
		unsigned int off_override;

		bool state;

	} ps;



#ifdef CONFIG_CARL9170_HWRNG

# define CARL9170_HWRNG_CACHE_SIZE	CARL9170_MAX_CMD_PAYLOAD_LEN

	struct {

		struct hwrng rng;

		bool initialized;

		char name[30 + 1];

		u16 cache[CARL9170_HWRNG_CACHE_SIZE / sizeof(u16)];

		unsigned int cache_idx;

	} rng;

#endif /* CONFIG_CARL9170_HWRNG */

};



enum carl9170_ps_off_override_reasons {

drivers/net/wireless/ath/carl9170/main.c

+113 −0
Original line number Diff line number Diff line
@@ -1468,6 +1468,109 @@ static int carl9170_register_wps_button(struct ar9170 *ar) 
}

#endif /* CONFIG_CARL9170_WPC */



#ifdef CONFIG_CARL9170_HWRNG

static int carl9170_rng_get(struct ar9170 *ar)

{



#define RW	(CARL9170_MAX_CMD_PAYLOAD_LEN / sizeof(u32))

#define RB	(CARL9170_MAX_CMD_PAYLOAD_LEN)



	static const __le32 rng_load[RW] = {

		[0 ... (RW - 1)] = cpu_to_le32(AR9170_RAND_REG_NUM)};



	u32 buf[RW];



	unsigned int i, off = 0, transfer, count;

	int err;



	BUILD_BUG_ON(RB > CARL9170_MAX_CMD_PAYLOAD_LEN);



	if (!IS_ACCEPTING_CMD(ar) || !ar->rng.initialized)

		return -EAGAIN;



	count = ARRAY_SIZE(ar->rng.cache);

	while (count) {

		err = carl9170_exec_cmd(ar, CARL9170_CMD_RREG,

					RB, (u8 *) rng_load,

					RB, (u8 *) buf);

		if (err)

			return err;



		transfer = min_t(unsigned int, count, RW);

		for (i = 0; i < transfer; i++)

			ar->rng.cache[off + i] = buf[i];



		off += transfer;

		count -= transfer;

	}



	ar->rng.cache_idx = 0;



#undef RW

#undef RB

	return 0;

}



static int carl9170_rng_read(struct hwrng *rng, u32 *data)

{

	struct ar9170 *ar = (struct ar9170 *)rng->priv;

	int ret = -EIO;



	mutex_lock(&ar->mutex);

	if (ar->rng.cache_idx >= ARRAY_SIZE(ar->rng.cache)) {

		ret = carl9170_rng_get(ar);

		if (ret) {

			mutex_unlock(&ar->mutex);

			return ret;

		}

	}



	*data = ar->rng.cache[ar->rng.cache_idx++];

	mutex_unlock(&ar->mutex);



	return sizeof(u16);

}



static void carl9170_unregister_hwrng(struct ar9170 *ar)

{

	if (ar->rng.initialized) {

		hwrng_unregister(&ar->rng.rng);

		ar->rng.initialized = false;

	}

}



static int carl9170_register_hwrng(struct ar9170 *ar)

{

	int err;



	snprintf(ar->rng.name, ARRAY_SIZE(ar->rng.name),

		 "%s_%s", KBUILD_MODNAME, wiphy_name(ar->hw->wiphy));

	ar->rng.rng.name = ar->rng.name;

	ar->rng.rng.data_read = carl9170_rng_read;

	ar->rng.rng.priv = (unsigned long)ar;



	if (WARN_ON(ar->rng.initialized))

		return -EALREADY;



	err = hwrng_register(&ar->rng.rng);

	if (err) {

		dev_err(&ar->udev->dev, "Failed to register the random "

			"number generator (%d)\n", err);

		return err;

	}



	ar->rng.initialized = true;



	err = carl9170_rng_get(ar);

	if (err) {

		carl9170_unregister_hwrng(ar);

		return err;

	}



	return 0;

}

#endif /* CONFIG_CARL9170_HWRNG */



static int carl9170_op_get_survey(struct ieee80211_hw *hw, int idx,

				struct survey_info *survey)

{
@@ -1878,6 +1981,12 @@ int carl9170_register(struct ar9170 *ar) 
		goto err_unreg;

#endif /* CONFIG_CARL9170_WPC */



#ifdef CONFIG_CARL9170_HWRNG

	err = carl9170_register_hwrng(ar);

	if (err)

		goto err_unreg;

#endif /* CONFIG_CARL9170_HWRNG */



	dev_info(&ar->udev->dev, "Atheros AR9170 is registered as '%s'\n",

		 wiphy_name(ar->hw->wiphy));
@@ -1910,6 +2019,10 @@ void carl9170_unregister(struct ar9170 *ar) 
	}

#endif /* CONFIG_CARL9170_WPC */



#ifdef CONFIG_CARL9170_HWRNG

	carl9170_unregister_hwrng(ar);

#endif /* CONFIG_CARL9170_HWRNG */



	carl9170_cancel_worker(ar);

	cancel_work_sync(&ar->restart_work);