kernel/include/net/nfc/digital.h, branch linux-4.15.y

NFC: digital: Add support for NFC DEP Response Waiting Time

2016-07-11T00:01:14Z

When sending an ATR_REQ, the initiator must wait for the ATR_RES at least 'RWT(nfcdep,activation) + dRWT(nfcdep)' and no more than 'RWT(nfcdep,activation) + dRWT(nfcdep) + dT(nfcdep,initiator)'. This gives a timeout value between 1237 ms and 1337 ms. This patch defines DIGITAL_ATR_RES_RWT to 1337 used for the timeout value of ATR_REQ command. For other DEP PDUs, the initiator must wait between 'RWT + dRWT(nfcdep)' and 'RWT + dRWT(nfcdep) + dT(nfcdep,initiator)' where RWT is given by the following formula: '(256 * 16 / f(c)) * 2^wt' where wt is the value of the TO field in the ATR_RES response and is in the range between 0 and 14. This patch declares a mapping table for wt values and gives RWT max values between 100 ms and 5049 ms. This patch also defines DIGITAL_ATR_RES_TO_WT, the maximum wt value in target mode, to 8. Signed-off-by: Thierry Escande Signed-off-by: Samuel Ortiz

NFC: digital: Fix handling of saved PDU sk_buff pointers

2016-07-10T23:55:42Z

This patch fixes the way an I-PDU is saved in case it needs to be sent again. It is now copied using pskb_copy() and not simply referenced using skb_get() since it could be modified by the driver. digital_in_send_saved_skb() and digital_tg_send_saved_skb() still get a reference on the saved skb which is re-sent but release it if the send operation fails. That way the caller doesn't have to take care about skb ref in case of error. RTOX supervisor PDU must not be saved as this can override a previously saved I-PDU that should be re-sent later on. Signed-off-by: Thierry Escande Signed-off-by: Samuel Ortiz

NFC: digital: Add a delay between poll cycles

2016-07-04T10:26:27Z

This replaces the polling work struct with a delayed work struct and add a 10 ms delay between 2 poll cycles. This avoids to flood the device with 'switch off'/'switch on' commands. Signed-off-by: Thierry Escande Signed-off-by: Samuel Ortiz

NFC: digital: Add NFC-DEP Initiator-side ATN Support

2014-11-28T11:39:55Z

When an NFC-DEP Initiator times out when waiting for a DEP_RES from the Target, its supposed to send an ATN to the Target. The Target should respond to the ATN with a similar ATN PDU and the Initiator can then resend the last non-ATN PDU that it sent. No more than 'N(retry,atn)' are to be send where 2 <= 'N(retry,atn)' <= 5. If the Initiator had just sent a NACK PDU when the timeout occurred, it is to continue sending NACKs until 'N(retry,nack)' NACKs have been send. This is described in section 14.12.5.6 of the NFC-DEP Digital Protocol Spec. The digital layer's NFC-DEP code doesn't implement this so add that support. The value chosen for 'N(retry,atn)' is 2. Reviewed-by: Thierry Escande Tested-by: Thierry Escande Signed-off-by: Mark A. Greer Signed-off-by: Samuel Ortiz

NFC: digital: Add NFC-DEP Target-side NACK Support

2014-11-28T11:39:47Z

When an NFC-DEP Target receives a NACK PDU with a PNI equal to 1 less than the current PNI, it is supposed to re-send the last PDU. This is implied in section 14.12.5.4 of the NFC Digital Protocol Spec. The digital layer's NFC-DEP code doesn't implement Target-side NACK handing so add it. The last PDU that was sent is saved in the 'nfc_digital_dev' structure's 'saved_skb' member. The skb will have an additional reference taken to ensure that the skb isn't freed when the driver performs a kfree_skb() on the skb. The length of the skb/PDU is also saved so the length can be restored when re-sending the PDU in the skb (the driver will perform an skb_pull() so an skb_push() needs to be done to restore the skb's data pointer/length). Reviewed-by: Thierry Escande Tested-by: Thierry Escande Signed-off-by: Mark A. Greer Signed-off-by: Samuel Ortiz

NFC: digital: Add NFC-DEP Initiator-side NACK Support

2014-11-28T11:39:33Z

When an NFC-DEP Initiator receives a frame with an incorrect CRC or with a parity error, and the frame is at least 4 bytes long, its supposed to send a NACK to the Target. The Initiator can send up to 'N(retry,nack)' consecutive NACKs where 2 <= 'N(retry,nack)' <= 5. When the limit is exceeded, a PROTOCOL EXCEPTION is raised. Any other type of transmission error is to be ignored and the Initiator should continue waiting for a new frame. This is described in section 14.12.5.4 of the NFC Digital Protocol Spec. The digital layer's NFC-DEP code doesn't implement any of this so add it. This support diverges from the spec in two significant ways: a) NACKs will be sent for ANY error reported by the driver except a timeout. This is done because there is currently no way for the digital layer to distinguish a CRC or parity error from any other type of error reported by the driver. b) All other errors will cause a PROTOCOL EXCEPTION even frames with CRC errors that are less than 4 bytes. The value chosen for 'N(retry,nack)' is 2. Targets do not send NACK PDUs. Reviewed-by: Thierry Escande Tested-by: Thierry Escande Signed-off-by: Mark A. Greer Signed-off-by: Samuel Ortiz

NFC: digital: Add NFC-DEP Send Chaining Support

2014-11-28T11:39:10Z

When the NFC-DEP code is given a packet to send that is larger than the peer's maximum payload, its supposed to set the 'MI' bit in the 'I' PDU's Protocol Frame Byte (PFB). Setting this bit indicates that NFC-DEP chaining is to occur. When NFC-DEP chaining is progress, sender 'I' PDUs are acknowledged with 'ACK' PDUs until the last 'I' PDU in the chain (which has the 'MI' bit cleared) is responded to with a normal 'I' PDU. This can occur while in Initiator mode or in Target mode. Sender NFC-DEP chaining is currently not implemented in the digital layer so add that support. Unfortunately, since sending a frame may require writing the CRC to the end of the data, the relevant data part of the original skb must be copied for each intermediate frame. Reviewed-by: Thierry Escande Tested-by: Thierry Escande Signed-off-by: Mark A. Greer Signed-off-by: Samuel Ortiz

NFC: digital: Implement NFC-DEP max payload lengths

2014-11-28T11:38:59Z

The maximum payload for NFC-DEP exchanges (i.e., the number of bytes between SoD and EoD) is negotiated using the ATR_REQ, ATR_RES, and PSL_REQ commands. The valid maximum lengths are 64, 128, 192, and 254 bytes. Currently, NFC-DEP code assumes that both sides are always using 254 byte maximums and ignores attempts by the peer to change it. Instead, implement the negotiation code, enforce the local maximum when receiving data from the peer, and don't send payloads that exceed the remote's maximum. The default local maximum is 254 bytes. Reviewed-by: Thierry Escande Tested-by: Thierry Escande Signed-off-by: Mark A. Greer Signed-off-by: Samuel Ortiz

NFC: digital: Add Target-mode NFC-DEP DID Support

2014-11-28T11:38:24Z

When in Target mode, the Initiator specifies whether subsequent DEP_REQ and DEP_RES frames will include a DID byte by the value passed in the ATR_REQ. If the DID value in the ATR_REQ is '0' then no DID byte will be included. If the DID value is between '1' and '14' then a DID byte containing the same value must be included in subsequent DEP_REQ and DEP_RES frames. Any other DID value is invalid. This is specified in sections 14.8.1.2 and 14.8.2.2 of the NFC Digital Protocol Spec. Checking the DID value (if it should be there at all), is not currently supported by the digital layer's NFC-DEP code. Add this support by remembering the DID value in the ATR_REQ, checking the DID value of received DEP_REQ frames (if it should be there at all), and including the remembered DID value in DEP_RES frames when appropriate. Reviewed-by: Thierry Escande Tested-by: Thierry Escande Signed-off-by: Mark A. Greer Signed-off-by: Samuel Ortiz

NFC: digital: Add 'tg_listen_md' and 'tg_get_rf_tech' driver hooks

2014-07-22T23:17:31Z

The digital layer of the NFC subsystem currently supports a 'tg_listen_mdaa' driver hook that supports devices that can do mode detection and automatic anticollision. However, there are some devices that can do mode detection but not automatic anitcollision so add the 'tg_listen_md' hook to support those devices. In order for the digital layer to get the RF technology detected by the device from the driver, add the 'tg_get_rf_tech' hook. It is only valid to call this hook immediately after a successful call to 'tg_listen_md'. CC: Thierry Escande Signed-off-by: Mark A. Greer Signed-off-by: Samuel Ortiz