NFC: Remove crc generation from shdlc layer

Checksum is specific for a chip spcification and it varies
(in size and type) between different hardware. It should be
handled in the driver then.

Moreover, shdlc spec doesn't mention crc as a part of the frame.

Update pn544_hci driver as well.

Signed-off-by: Waldemar Rymarkiewicz <waldemar.rymarkiewicz@tieto.com>
Acked-by: Eric Lapuyade <eric.lapuyade@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 30 insertions, 2 deletions

diff --git a/drivers/nfc/pn544_hci.c b/drivers/nfc/pn544_hci.c
index 9458d53cdb59..d90aecfce739 100644
--- a/drivers/nfc/pn544_hci.c
+++ b/drivers/nfc/pn544_hci.c
@@ -128,6 +128,8 @@ static struct nfc_hci_gate pn544_gates[] = {
 
 /* Largest headroom needed for outgoing custom commands */
 #define PN544_CMDS_HEADROOM     2
+#define PN544_FRAME_HEADROOM 1
+#define PN544_FRAME_TAILROOM 2
 
 struct pn544_hci_info {
         struct i2c_client *i2c_dev;
@@ -576,15 +578,40 @@ static int pn544_hci_ready(struct nfc_shdlc *shdlc)
         return 0;
 }
 
+static void pn544_hci_add_len_crc(struct sk_buff *skb)
+{
+        u16 crc;
+        int len;
+
+        len = skb->len + 2;
+        *skb_push(skb, 1) = len;
+
+        crc = crc_ccitt(0xffff, skb->data, skb->len);
+        crc = ~crc;
+        *skb_put(skb, 1) = crc & 0xff;
+        *skb_put(skb, 1) = crc >> 8;
+}
+
+static void pn544_hci_remove_len_crc(struct sk_buff *skb)
+{
+        skb_pull(skb, PN544_FRAME_HEADROOM);
+        skb_trim(skb, PN544_FRAME_TAILROOM);
+}
+
 static int pn544_hci_xmit(struct nfc_shdlc *shdlc, struct sk_buff *skb)
 {
         struct pn544_hci_info *info = nfc_shdlc_get_clientdata(shdlc);
         struct i2c_client *client = info->i2c_dev;
+        int r;
 
         if (info->hard_fault != 0)
                 return info->hard_fault;
 
-        return pn544_hci_i2c_write(client, skb->data, skb->len);
+        pn544_hci_add_len_crc(skb);
+        r = pn544_hci_i2c_write(client, skb->data, skb->len);
+        pn544_hci_remove_len_crc(skb);
+
+        return r;
 }
 
 static int pn544_hci_start_poll(struct nfc_shdlc *shdlc,
@@ -874,7 +901,8 @@ static int __devinit pn544_hci_probe(struct i2c_client *client,
 
         info->shdlc = nfc_shdlc_allocate(&pn544_shdlc_ops,
                                          &init_data, protocols,
-                                         PN544_CMDS_HEADROOM, 0,
+                                         PN544_FRAME_HEADROOM + PN544_CMDS_HEADROOM,
+                                         PN544_FRAME_TAILROOM,
                                          PN544_HCI_LLC_MAX_PAYLOAD,
                                          dev_name(&client->dev));
         if (!info->shdlc) {