diff --git a/drivers/net/ieee802154/cc2520.c b/drivers/net/ieee802154/cc2520.c
index e65b605..d50add7 100644
--- a/drivers/net/ieee802154/cc2520.c
+++ b/drivers/net/ieee802154/cc2520.c
@@ -21,6 +21,8 @@
 #include <linux/skbuff.h>
 #include <linux/of_gpio.h>
 #include <linux/ieee802154.h>
+#include <linux/crc-ccitt.h>
+#include <asm/unaligned.h>
 
 #include <net/mac802154.h>
 #include <net/cfg802154.h>
@@ -189,6 +191,18 @@
 #define	CC2520_RXFIFOCNT		0x3E
 #define	CC2520_TXFIFOCNT		0x3F
 
+/* CC2520_FRMFILT0 */
+#define FRMFILT0_FRAME_FILTER_EN	BIT(0)
+#define FRMFILT0_PAN_COORDINATOR	BIT(1)
+
+/* CC2520_FRMCTRL0 */
+#define FRMCTRL0_AUTOACK		BIT(5)
+#define FRMCTRL0_AUTOCRC		BIT(6)
+
+/* CC2520_FRMCTRL1 */
+#define FRMCTRL1_SET_RXENMASK_ON_TX	BIT(0)
+#define FRMCTRL1_IGNORE_TX_UNDERF	BIT(1)
+
 /* Driver private information */
 struct cc2520_private {
 	struct spi_device *spi;		/* SPI device structure */
@@ -201,6 +215,7 @@ struct cc2520_private {
 	struct work_struct fifop_irqwork;/* Workqueue for FIFOP */
 	spinlock_t lock;		/* Lock for is_tx*/
 	struct completion tx_complete;	/* Work completion for Tx */
+	bool promiscuous;               /* Flag for promiscuous mode */
 };
 
 /* Generic Functions */
@@ -367,14 +382,14 @@ cc2520_read_register(struct cc2520_private *priv, u8 reg, u8 *data)
 }
 
 static int
-cc2520_write_txfifo(struct cc2520_private *priv, u8 *data, u8 len)
+cc2520_write_txfifo(struct cc2520_private *priv, u8 pkt_len, u8 *data, u8 len)
 {
 	int status;
 
 	/* length byte must include FCS even
 	 * if it is calculated in the hardware
 	 */
-	int len_byte = len + 2;
+	int len_byte = pkt_len;
 
 	struct spi_message msg;
 
@@ -414,7 +429,7 @@ cc2520_write_txfifo(struct cc2520_private *priv, u8 *data, u8 len)
 }
 
 static int
-cc2520_read_rxfifo(struct cc2520_private *priv, u8 *data, u8 len, u8 *lqi)
+cc2520_read_rxfifo(struct cc2520_private *priv, u8 *data, u8 len)
 {
 	int status;
 	struct spi_message msg;
@@ -470,12 +485,25 @@ cc2520_tx(struct ieee802154_hw *hw, struct sk_buff *skb)
 	unsigned long flags;
 	int rc;
 	u8 status = 0;
+	u8 pkt_len;
+
+	/* In promiscuous mode we disable AUTOCRC so we can get the raw CRC
+	 * values on RX. This means we need to manually add the CRC on TX.
+	 */
+	if (priv->promiscuous) {
+		u16 crc = crc_ccitt(0, skb->data, skb->len);
+
+		put_unaligned_le16(crc, skb_put(skb, 2));
+		pkt_len = skb->len;
+	} else {
+		pkt_len = skb->len + 2;
+	}
 
 	rc = cc2520_cmd_strobe(priv, CC2520_CMD_SFLUSHTX);
 	if (rc)
 		goto err_tx;
 
-	rc = cc2520_write_txfifo(priv, skb->data, skb->len);
+	rc = cc2520_write_txfifo(priv, pkt_len, skb->data, skb->len);
 	if (rc)
 		goto err_tx;
 
@@ -518,22 +546,62 @@ static int cc2520_rx(struct cc2520_private *priv)
 	u8 len = 0, lqi = 0, bytes = 1;
 	struct sk_buff *skb;
 
-	cc2520_read_rxfifo(priv, &len, bytes, &lqi);
+	/* Read single length byte from the radio. */
+	cc2520_read_rxfifo(priv, &len, bytes);
 
-	if (len < 2 || len > IEEE802154_MTU)
-		return -EINVAL;
+	if (!ieee802154_is_valid_psdu_len(len)) {
+		/* Corrupted frame received, clear frame buffer by
+		 * reading entire buffer.
+		 */
+		dev_dbg(&priv->spi->dev, "corrupted frame received\n");
+		len = IEEE802154_MTU;
+	}
 
 	skb = dev_alloc_skb(len);
 	if (!skb)
 		return -ENOMEM;
 
-	if (cc2520_read_rxfifo(priv, skb_put(skb, len), len, &lqi)) {
+	if (cc2520_read_rxfifo(priv, skb_put(skb, len), len)) {
 		dev_dbg(&priv->spi->dev, "frame reception failed\n");
 		kfree_skb(skb);
 		return -EINVAL;
 	}
 
-	skb_trim(skb, skb->len - 2);
+	/* In promiscuous mode, we configure the radio to include the
+	 * CRC (AUTOCRC==0) and we pass on the packet unconditionally. If not
+	 * in promiscuous mode, we check the CRC here, but leave the
+	 * RSSI/LQI/CRC_OK bytes as they will get removed in the mac layer.
+	 */
+	if (!priv->promiscuous) {
+		bool crc_ok;
+
+		/* Check if the CRC is valid. With AUTOCRC set, the most
+		 * significant bit of the last byte returned from the CC2520
+		 * is CRC_OK flag. See section 20.3.4 of the datasheet.
+		 */
+		crc_ok = skb->data[len - 1] & BIT(7);
+
+		/* If we failed CRC drop the packet in the driver layer. */
+		if (!crc_ok) {
+			dev_dbg(&priv->spi->dev, "CRC check failed\n");
+			kfree_skb(skb);
+			return -EINVAL;
+		}
+
+		/* To calculate LQI, the lower 7 bits of the last byte (the
+		 * correlation value provided by the radio) must be scaled to
+		 * the range 0-255. According to section 20.6, the correlation
+		 * value ranges from 50-110. Ideally this would be calibrated
+		 * per hardware design, but we use roughly the datasheet values
+		 * to get close enough while avoiding floating point.
+		 */
+		lqi = skb->data[len - 1] & 0x7f;
+		if (lqi < 50)
+			lqi = 50;
+		else if (lqi > 113)
+			lqi = 113;
+		lqi = (lqi - 50) * 4;
+	}
 
 	ieee802154_rx_irqsafe(priv->hw, skb, lqi);
 
@@ -619,14 +687,19 @@ cc2520_filter(struct ieee802154_hw *hw,
 	}
 
 	if (changed & IEEE802154_AFILT_PANC_CHANGED) {
+		u8 frmfilt0;
+
 		dev_vdbg(&priv->spi->dev,
 			 "cc2520_filter called for panc change\n");
+
+		cc2520_read_register(priv, CC2520_FRMFILT0, &frmfilt0);
+
 		if (filt->pan_coord)
-			ret = cc2520_write_register(priv, CC2520_FRMFILT0,
-						    0x02);
+			frmfilt0 |= FRMFILT0_PAN_COORDINATOR;
 		else
-			ret = cc2520_write_register(priv, CC2520_FRMFILT0,
-						    0x00);
+			frmfilt0 &= ~FRMFILT0_PAN_COORDINATOR;
+
+		ret = cc2520_write_register(priv, CC2520_FRMFILT0, frmfilt0);
 	}
 
 	return ret;
@@ -723,6 +796,30 @@ cc2520_set_txpower(struct ieee802154_hw *hw, s32 mbm)
 	return cc2520_cc2591_set_tx_power(priv, mbm);
 }
 
+static int
+cc2520_set_promiscuous_mode(struct ieee802154_hw *hw, bool on)
+{
+	struct cc2520_private *priv = hw->priv;
+	u8 frmfilt0;
+
+	dev_dbg(&priv->spi->dev, "%s : mode %d\n", __func__, on);
+
+	priv->promiscuous = on;
+
+	cc2520_read_register(priv, CC2520_FRMFILT0, &frmfilt0);
+
+	if (on) {
+		/* Disable automatic ACK, automatic CRC, and frame filtering. */
+		cc2520_write_register(priv, CC2520_FRMCTRL0, 0);
+		frmfilt0 &= ~FRMFILT0_FRAME_FILTER_EN;
+	} else {
+		cc2520_write_register(priv, CC2520_FRMCTRL0, FRMCTRL0_AUTOACK |
+							     FRMCTRL0_AUTOCRC);
+		frmfilt0 |= FRMFILT0_FRAME_FILTER_EN;
+	}
+	return cc2520_write_register(priv, CC2520_FRMFILT0, frmfilt0);
+}
+
 static const struct ieee802154_ops cc2520_ops = {
 	.owner = THIS_MODULE,
 	.start = cc2520_start,
@@ -732,6 +829,7 @@ static const struct ieee802154_ops cc2520_ops = {
 	.set_channel = cc2520_set_channel,
 	.set_hw_addr_filt = cc2520_filter,
 	.set_txpower = cc2520_set_txpower,
+	.set_promiscuous_mode = cc2520_set_promiscuous_mode,
 };
 
 static int cc2520_register(struct cc2520_private *priv)
@@ -749,7 +847,8 @@ static int cc2520_register(struct cc2520_private *priv)
 
 	/* We do support only 2.4 Ghz */
 	priv->hw->phy->supported.channels[0] = 0x7FFF800;
-	priv->hw->flags = IEEE802154_HW_OMIT_CKSUM | IEEE802154_HW_AFILT;
+	priv->hw->flags = IEEE802154_HW_TX_OMIT_CKSUM | IEEE802154_HW_AFILT |
+			  IEEE802154_HW_PROMISCUOUS;
 
 	priv->hw->phy->flags = WPAN_PHY_FLAG_TXPOWER;
 
@@ -919,6 +1018,11 @@ static int cc2520_hw_init(struct cc2520_private *priv)
 	}
 
 	/* Registers default value: section 28.1 in Datasheet */
+
+	/* Set the CCA threshold to -50 dBm. This seems to have been copied
+	 * from the TinyOS CC2520 driver and is much higher than the -84 dBm
+	 * threshold suggested in the datasheet.
+	 */
 	ret = cc2520_write_register(priv, CC2520_CCACTRL0, 0x1A);
 	if (ret)
 		goto err_ret;
@@ -955,15 +1059,10 @@ static int cc2520_hw_init(struct cc2520_private *priv)
 	if (ret)
 		goto err_ret;
 
-	ret = cc2520_write_register(priv, CC2520_FRMCTRL0, 0x60);
-	if (ret)
-		goto err_ret;
-
-	ret = cc2520_write_register(priv, CC2520_FRMCTRL1, 0x03);
-	if (ret)
-		goto err_ret;
-
-	ret = cc2520_write_register(priv, CC2520_FRMFILT0, 0x00);
+	/* Configure registers correctly for this driver. */
+	ret = cc2520_write_register(priv, CC2520_FRMCTRL1,
+				    FRMCTRL1_SET_RXENMASK_ON_TX |
+				    FRMCTRL1_IGNORE_TX_UNDERF);
 	if (ret)
 		goto err_ret;
 
