This patch adds checking the "CRC_OK" bit at the end of packets coming
from the CC2520 radio. It also adds support for putting the radio in
promiscuous mode (in which packets are not dropped if the CRC fails).
In order to provide monitors information about CRC pass/fail, the CRC is
recreated in the driver and appended to the packet before being passed
to higher layers. If the CRC failed, a dummy CRC is appended.
NOTE: This is an API breaking change for the CC2520 radio. The radio now
defaults to frame filtering (checking that the destination and PANID in
the incoming packet matches the local node). This matches the other
15.4 radios and is what a user would expect to be the default.
Other changes:
1. Adds LQI calculation
2. Makes #defines for relevant bit fields in CC2520 registers
Signed-off-by: Brad Campbell <bradjc5@xxxxxxxxx>
---
drivers/net/ieee802154/cc2520.c | 128 ++++++++++++++++++++++++++++++++++------
1 file changed, 111 insertions(+), 17 deletions(-)
diff --git a/drivers/net/ieee802154/cc2520.c b/drivers/net/ieee802154/cc2520.c
index e65b605..3d66717 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 */
@@ -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;
@@ -516,24 +531,67 @@ err_tx:
static int cc2520_rx(struct cc2520_private *priv)
{
u8 len = 0, lqi = 0, bytes = 1;
+ bool crc_ok;
+ u16 crc;
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);
+ /* Check if the CRC is valid and calculate LQI. 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. 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.
+ */
+ crc_ok = skb->data[len - 1] & BIT(7);
+ lqi = skb->data[len - 1] & 0x7f;
+ if (lqi < 50)
+ lqi = 50;
+ else if (lqi > 113)
+ lqi = 113;
+ lqi = (lqi - 50) * 4;
+
+ /* If we failed CRC and we are not in promiscuous mode, drop the
+ * packet in the driver layer.
+ */
+ if (!crc_ok && !priv->promiscuous) {
+ dev_dbg(&priv->spi->dev, "CRC check failed\n");
+ kfree_skb(skb);
+ return -EINVAL;
+ }
+
+ /* We pass the packet up to the mac layer if the CRC is valid or
+ * unconditionally in promiscuous mode. We do need to append the
+ * original CRC bytes for the upper layer, and we calculate them
+ * here so that we can ensure that we append a bad CRC if the check
+ * failed.
+ */
+ crc = crc_ccitt(0, skb->data, skb->len - 2);
+ if (!crc_ok)
+ crc = ~crc;
+ put_unaligned_le16(crc, skb->data + len - 2);
ieee802154_rx_irqsafe(priv->hw, skb, lqi);
@@ -619,14 +677,19 @@ 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 +786,30 @@ 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 and frame filtering. */
+ cc2520_write_register(priv, CC2520_FRMCTRL0, FRMCTRL0_AUTOCRC);
+ 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 +819,7 @@ 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 +837,8 @@ 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 +1008,11 @@ 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 +1049,15 @@ 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);
+ /* Configure registers correctly for this driver. */
+ ret = cc2520_write_register(priv, CC2520_FRMCTRL0, FRMCTRL0_AUTOACK |
+ FRMCTRL0_AUTOCRC);
if (ret)
goto err_ret;
- ret = cc2520_write_register(priv, CC2520_FRMFILT0, 0x00);
+ ret = cc2520_write_register(priv, CC2520_FRMCTRL1,
+ FRMCTRL1_SET_RXENMASK_ON_TX |
+ FRMCTRL1_IGNORE_TX_UNDERF);
if (ret)
goto err_ret;
--
2.6.3
--
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