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
--- a/include/net/nfc/digital.h
+++ b/include/net/nfc/digital.h
@@ -226,6 +226,7 @@
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
--- 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 @@
[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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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);