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

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 <thierry.escande@collabora.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

diff --git a/include/net/nfc/digital.h b/include/net/nfc/digital.h
index f9a4e47..74fa7eb 100644 (file)
--- a/include/net/nfc/digital.h
+++ b/include/net/nfc/digital.h
@@ -226,6 +226,7 @@ struct nfc_digital_dev {
        u8 curr_rf_tech;
        u8 curr_nfc_dep_pni;
        u8 did;
+       u16 dep_rwt;
 
        u8 local_payload_max;
        u8 remote_payload_max;

diff --git a/net/nfc/digital_dep.c b/net/nfc/digital_dep.c
index ba52a5d..6cf2eeb 100644 (file)
--- a/net/nfc/digital_dep.c
+++ b/net/nfc/digital_dep.c
@@ -35,6 +35,8 @@
 #define DIGITAL_ATR_REQ_MIN_SIZE 16
 #define DIGITAL_ATR_REQ_MAX_SIZE 64
 
+#define DIGITAL_ATR_RES_TO_WT(s)       ((s) & 0xF)
+
 #define DIGITAL_DID_MAX        14
 
 #define DIGITAL_PAYLOAD_SIZE_MAX       254
@@ -122,6 +124,37 @@ static const u8 digital_payload_bits_map[4] = {
        [3] = 254
 };
 
+/* Response Waiting Time for ATR_RES PDU in ms
+ *
+ * RWT(ATR_RES) = RWT(nfcdep,activation) + dRWT(nfcdep) + dT(nfcdep,initiator)
+ *
+ * with:
+ *  RWT(nfcdep,activation) = 4096 * 2^12 / f(c) s
+ *  dRWT(nfcdep) = 16 / f(c) s
+ *  dT(nfcdep,initiator) = 100 ms
+ *  f(c) = 13560000 Hz
+ */
+#define DIGITAL_ATR_RES_RWT 1337
+
+/* Response Waiting Time for other DEP PDUs in ms
+ *
+ * max_rwt = rwt + dRWT(nfcdep) + dT(nfcdep,initiator)
+ *
+ * with:
+ *  rwt = (256 * 16 / f(c)) * 2^wt s
+ *  dRWT(nfcdep) = 16 / f(c) s
+ *  dT(nfcdep,initiator) = 100 ms
+ *  f(c) = 13560000 Hz
+ *  0 <= wt <= 14 (given by the target by the TO field of ATR_RES response)
+ */
+#define DIGITAL_NFC_DEP_IN_MAX_WT 14
+#define DIGITAL_NFC_DEP_TG_MAX_WT 8
+static const u16 digital_rwt_map[DIGITAL_NFC_DEP_IN_MAX_WT + 1] = {
+       100,  101,  101,  102,  105,
+       110,  119,  139,  177,  255,
+       409,  719, 1337, 2575, 5049,
+};
+
 static u8 digital_payload_bits_to_size(u8 payload_bits)
 {
        if (payload_bits >= ARRAY_SIZE(digital_payload_bits_map))
@@ -366,8 +399,8 @@ static int digital_in_send_psl_req(struct nfc_digital_dev *ddev,
 
        ddev->skb_add_crc(skb);
 
-       rc = digital_in_send_cmd(ddev, skb, 500, digital_in_recv_psl_res,
-                                target);
+       rc = digital_in_send_cmd(ddev, skb, ddev->dep_rwt,
+                                digital_in_recv_psl_res, target);
        if (rc)
                kfree_skb(skb);
 
@@ -380,6 +413,7 @@ static void digital_in_recv_atr_res(struct nfc_digital_dev *ddev, void *arg,
        struct nfc_target *target = arg;
        struct digital_atr_res *atr_res;
        u8 gb_len, payload_bits;
+       u8 wt;
        int rc;
 
        if (IS_ERR(resp)) {
@@ -409,6 +443,11 @@ static void digital_in_recv_atr_res(struct nfc_digital_dev *ddev, void *arg,
 
        atr_res = (struct digital_atr_res *)resp->data;
 
+       wt = DIGITAL_ATR_RES_TO_WT(atr_res->to);
+       if (wt > DIGITAL_NFC_DEP_IN_MAX_WT)
+               wt = DIGITAL_NFC_DEP_IN_MAX_WT;
+       ddev->dep_rwt = digital_rwt_map[wt];
+
        payload_bits = DIGITAL_PAYLOAD_PP_TO_BITS(atr_res->pp);
        ddev->remote_payload_max = digital_payload_bits_to_size(payload_bits);
 
@@ -490,8 +529,8 @@ int digital_in_send_atr_req(struct nfc_digital_dev *ddev,
 
        ddev->skb_add_crc(skb);
 
-       rc = digital_in_send_cmd(ddev, skb, 500, digital_in_recv_atr_res,
-                                target);
+       rc = digital_in_send_cmd(ddev, skb, DIGITAL_ATR_RES_RWT,
+                                digital_in_recv_atr_res, target);
        if (rc)
                kfree_skb(skb);
 
@@ -524,8 +563,8 @@ static int digital_in_send_ack(struct nfc_digital_dev *ddev,
 
        ddev->saved_skb = pskb_copy(skb, GFP_KERNEL);
 
-       rc = digital_in_send_cmd(ddev, skb, 1500, digital_in_recv_dep_res,
-                                data_exch);
+       rc = digital_in_send_cmd(ddev, skb, ddev->dep_rwt,
+                                digital_in_recv_dep_res, data_exch);
        if (rc) {
                kfree_skb(skb);
                kfree_skb(ddev->saved_skb);
@@ -559,8 +598,8 @@ static int digital_in_send_nack(struct nfc_digital_dev *ddev,
 
        ddev->skb_add_crc(skb);
 
-       rc = digital_in_send_cmd(ddev, skb, 1500, digital_in_recv_dep_res,
-                                data_exch);
+       rc = digital_in_send_cmd(ddev, skb, ddev->dep_rwt,
+                                digital_in_recv_dep_res, data_exch);
        if (rc)
                kfree_skb(skb);
 
@@ -590,8 +629,8 @@ static int digital_in_send_atn(struct nfc_digital_dev *ddev,
 
        ddev->skb_add_crc(skb);
 
-       rc = digital_in_send_cmd(ddev, skb, 1500, digital_in_recv_dep_res,
-                                data_exch);
+       rc = digital_in_send_cmd(ddev, skb, ddev->dep_rwt,
+                                digital_in_recv_dep_res, data_exch);
        if (rc)
                kfree_skb(skb);
 
@@ -624,8 +663,8 @@ static int digital_in_send_rtox(struct nfc_digital_dev *ddev,
 
        ddev->skb_add_crc(skb);
 
-       rc = digital_in_send_cmd(ddev, skb, 1500, digital_in_recv_dep_res,
-                                data_exch);
+       rc = digital_in_send_cmd(ddev, skb, ddev->dep_rwt,
+                                digital_in_recv_dep_res, data_exch);
        if (rc)
                kfree_skb(skb);
 
@@ -642,7 +681,7 @@ static int digital_in_send_saved_skb(struct nfc_digital_dev *ddev,
 
        skb_get(ddev->saved_skb);
 
-       rc = digital_in_send_cmd(ddev, ddev->saved_skb, 1500,
+       rc = digital_in_send_cmd(ddev, ddev->saved_skb, ddev->dep_rwt,
                                 digital_in_recv_dep_res, data_exch);
        if (rc)
                kfree_skb(ddev->saved_skb);
@@ -885,8 +924,8 @@ int digital_in_send_dep_req(struct nfc_digital_dev *ddev,
 
        ddev->saved_skb = pskb_copy(tmp_skb, GFP_KERNEL);
 
-       rc = digital_in_send_cmd(ddev, tmp_skb, 1500, digital_in_recv_dep_res,
-                                data_exch);
+       rc = digital_in_send_cmd(ddev, tmp_skb, ddev->dep_rwt,
+                                digital_in_recv_dep_res, data_exch);
        if (rc) {
                if (tmp_skb != skb)
                        kfree_skb(tmp_skb);
@@ -1465,7 +1504,7 @@ static int digital_tg_send_atr_res(struct nfc_digital_dev *ddev,
        atr_res->dir = DIGITAL_NFC_DEP_FRAME_DIR_IN;
        atr_res->cmd = DIGITAL_CMD_ATR_RES;
        memcpy(atr_res->nfcid3, atr_req->nfcid3, sizeof(atr_req->nfcid3));
-       atr_res->to = 8;
+       atr_res->to = DIGITAL_NFC_DEP_TG_MAX_WT;
 
        ddev->local_payload_max = DIGITAL_PAYLOAD_SIZE_MAX;
        payload_bits = digital_payload_size_to_bits(ddev->local_payload_max);