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: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/carl9170/main.c b/drivers/net/wireless/ath/carl9170/main.c
index 85cb1bd..782b8f3 100644
--- a/drivers/net/wireless/ath/carl9170/main.c
+++ b/drivers/net/wireless/ath/carl9170/main.c
@@ -1468,6 +1468,109 @@
}
#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 @@
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 @@
}
#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);