NFC Digital: Add NFC-F technology support

This adds polling support for NFC-F technology at 212 kbits/s and 424
kbits/s. A user space application like neard can send type 3 tag
commands through the NFC core.

Process flow for NFC-F detection is as follow:

1 - The digital stack sends the SENSF_REQ command to the NFC device.
2 - A peer device replies with a SENSF_RES response.
3   - The digital stack notifies the NFC core of the presence of a
      target in the operation field and passes the target NFCID2.

This also adds support for CRC calculation of type CRC-F. The CRC
calculation is handled by the digital stack if the NFC device doesn't
support it.

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

4 files changed, 153 insertions, 0 deletions

diff --git a/net/nfc/Kconfig b/net/nfc/Kconfig
index 4f4d2481325a..6e0fa0cce198 100644
--- a/net/nfc/Kconfig
+++ b/net/nfc/Kconfig
@@ -17,6 +17,7 @@ menuconfig NFC
 config NFC_DIGITAL
 	depends on NFC
 	select CRC_CCITT
+	select CRC_ITU_T
 	tristate "NFC Digital Protocol stack support"
 	default n
 	help
diff --git a/net/nfc/digital.h b/net/nfc/digital.h
index fb5324b792de..85bc74c988f8 100644
--- a/net/nfc/digital.h
+++ b/net/nfc/digital.h
@@ -20,6 +20,7 @@
 #include <net/nfc/digital.h>
 
 #include <linux/crc-ccitt.h>
+#include <linux/crc-itu-t.h>
 
 #define PR_DBG(fmt, ...)  pr_debug("%s: " fmt "\n", __func__, ##__VA_ARGS__)
 #define PR_ERR(fmt, ...)  pr_err("%s: " fmt "\n", __func__, ##__VA_ARGS__)
@@ -64,6 +65,7 @@ static inline int digital_in_send_cmd(struct nfc_digital_dev *ddev,
 void digital_poll_next_tech(struct nfc_digital_dev *ddev);
 
 int digital_in_send_sens_req(struct nfc_digital_dev *ddev, u8 rf_tech);
+int digital_in_send_sensf_req(struct nfc_digital_dev *ddev, u8 rf_tech);
 
 int digital_target_found(struct nfc_digital_dev *ddev,
 			 struct nfc_target *target, u8 protocol);
@@ -74,6 +76,7 @@ typedef u16 (*crc_func_t)(u16, const u8 *, size_t);
 
 #define CRC_A_INIT 0x6363
 #define CRC_B_INIT 0xFFFF
+#define CRC_F_INIT 0x0000
 
 void digital_skb_add_crc(struct sk_buff *skb, crc_func_t crc_func, u16 init,
 			 u8 bitwise_inv, u8 msb_first);
@@ -88,6 +91,11 @@ static inline void digital_skb_add_crc_b(struct sk_buff *skb)
 	digital_skb_add_crc(skb, crc_ccitt, CRC_B_INIT, 1, 0);
 }
 
+static inline void digital_skb_add_crc_f(struct sk_buff *skb)
+{
+	digital_skb_add_crc(skb, crc_itu_t, CRC_F_INIT, 0, 1);
+}
+
 static inline void digital_skb_add_crc_none(struct sk_buff *skb)
 {
 	return;
@@ -106,6 +114,11 @@ static inline int digital_skb_check_crc_b(struct sk_buff *skb)
 	return digital_skb_check_crc(skb, crc_ccitt, CRC_B_INIT, 1, 0);
 }
 
+static inline int digital_skb_check_crc_f(struct sk_buff *skb)
+{
+	return digital_skb_check_crc(skb, crc_itu_t, CRC_F_INIT, 0, 1);
+}
+
 static inline int digital_skb_check_crc_none(struct sk_buff *skb)
 {
 	return 0;
diff --git a/net/nfc/digital_core.c b/net/nfc/digital_core.c
index 4b3ceb45834b..25e5bcb946e0 100644
--- a/net/nfc/digital_core.c
+++ b/net/nfc/digital_core.c
@@ -20,6 +20,8 @@
 #define DIGITAL_PROTO_NFCA_RF_TECH \
 	(NFC_PROTO_JEWEL_MASK | NFC_PROTO_MIFARE_MASK)
 
+#define DIGITAL_PROTO_NFCF_RF_TECH (NFC_PROTO_FELICA_MASK)
+
 struct digital_cmd {
 	struct list_head queue;
 
@@ -252,6 +254,12 @@ int digital_target_found(struct nfc_digital_dev *ddev,
 		add_crc = digital_skb_add_crc_a;
 		break;
 
+	case NFC_PROTO_FELICA:
+		framing = NFC_DIGITAL_FRAMING_NFCF_T3T;
+		check_crc = digital_skb_check_crc_f;
+		add_crc = digital_skb_add_crc_f;
+		break;
+
 	default:
 		PR_ERR("Invalid protocol %d", protocol);
 		return -EINVAL;
@@ -383,6 +391,14 @@ static int digital_start_poll(struct nfc_dev *nfc_dev, __u32 im_protocols,
 		digital_add_poll_tech(ddev, NFC_DIGITAL_RF_TECH_106A,
 				      digital_in_send_sens_req);
 
+	if (im_protocols & DIGITAL_PROTO_NFCF_RF_TECH) {
+		digital_add_poll_tech(ddev, NFC_DIGITAL_RF_TECH_212F,
+				      digital_in_send_sensf_req);
+
+		digital_add_poll_tech(ddev, NFC_DIGITAL_RF_TECH_424F,
+				      digital_in_send_sensf_req);
+	}
+
 	if (!ddev->poll_tech_count) {
 		PR_ERR("Unsupported protocols: im=0x%x, tm=0x%x",
 		       matching_im_protocols, matching_tm_protocols);
@@ -560,6 +576,8 @@ struct nfc_digital_dev *nfc_digital_allocate_device(struct nfc_digital_ops *ops,
 		ddev->protocols |= NFC_PROTO_JEWEL_MASK;
 	if (supported_protocols & NFC_PROTO_MIFARE_MASK)
 		ddev->protocols |= NFC_PROTO_MIFARE_MASK;
+	if (supported_protocols & NFC_PROTO_FELICA_MASK)
+		ddev->protocols |= NFC_PROTO_FELICA_MASK;
 
 	ddev->tx_headroom = tx_headroom + DIGITAL_MAX_HEADER_LEN;
 	ddev->tx_tailroom = tx_tailroom + DIGITAL_CRC_LEN;
diff --git a/net/nfc/digital_technology.c b/net/nfc/digital_technology.c
index 0cad38001c5f..bfe5ae17909e 100644
--- a/net/nfc/digital_technology.c
+++ b/net/nfc/digital_technology.c
@@ -37,6 +37,17 @@
 #define DIGITAL_MIFARE_READ_RES_LEN 16
 #define DIGITAL_MIFARE_ACK_RES	0x0A
 
+#define DIGITAL_CMD_SENSF_REQ	0x00
+#define DIGITAL_CMD_SENSF_RES	0x01
+
+#define DIGITAL_SENSF_RES_MIN_LENGTH 17
+#define DIGITAL_SENSF_RES_RD_AP_B1   0x00
+#define DIGITAL_SENSF_RES_RD_AP_B2   0x8F
+
+#define DIGITAL_SENSF_REQ_RC_NONE 0
+#define DIGITAL_SENSF_REQ_RC_SC   1
+#define DIGITAL_SENSF_REQ_RC_AP   2
+
 struct digital_sdd_res {
 	u8 nfcid1[4];
 	u8 bcc;
@@ -49,6 +60,25 @@ struct digital_sel_req {
 	u8 bcc;
 } __packed;
 
+struct digital_sensf_req {
+	u8 cmd;
+	u8 sc1;
+	u8 sc2;
+	u8 rc;
+	u8 tsn;
+} __packed;
+
+struct digital_sensf_res {
+	u8 cmd;
+	u8 nfcid2[8];
+	u8 pad0[2];
+	u8 pad1[3];
+	u8 mrti_check;
+	u8 mrti_update;
+	u8 pad2;
+	u8 rd[2];
+} __packed;
+
 static int digital_in_send_sdd_req(struct nfc_digital_dev *ddev,
 				   struct nfc_target *target);
 
@@ -344,3 +374,94 @@ int digital_in_recv_mifare_res(struct sk_buff *resp)
 	/* NACK and any other responses are treated as error. */
 	return -EIO;
 }
+
+static void digital_in_recv_sensf_res(struct nfc_digital_dev *ddev, void *arg,
+				   struct sk_buff *resp)
+{
+	int rc;
+	struct nfc_target target;
+	struct digital_sensf_res *sensf_res;
+
+	if (IS_ERR(resp)) {
+		rc = PTR_ERR(resp);
+		resp = NULL;
+		goto exit;
+	}
+
+	if (resp->len < DIGITAL_SENSF_RES_MIN_LENGTH) {
+		rc = -EIO;
+		goto exit;
+	}
+
+	if (!DIGITAL_DRV_CAPS_IN_CRC(ddev)) {
+		rc = digital_skb_check_crc_f(resp);
+		if (rc) {
+			PROTOCOL_ERR("6.4.1.8");
+			goto exit;
+		}
+	}
+
+	skb_pull(resp, 1);
+
+	memset(&target, 0, sizeof(struct nfc_target));
+
+	sensf_res = (struct digital_sensf_res *)resp->data;
+
+	memcpy(target.sensf_res, sensf_res, resp->len);
+	target.sensf_res_len = resp->len;
+
+	memcpy(target.nfcid2, sensf_res->nfcid2, NFC_NFCID2_MAXSIZE);
+	target.nfcid2_len = NFC_NFCID2_MAXSIZE;
+
+	rc = digital_target_found(ddev, &target, NFC_PROTO_FELICA);
+
+exit:
+	dev_kfree_skb(resp);
+
+	if (rc)
+		digital_poll_next_tech(ddev);
+}
+
+int digital_in_send_sensf_req(struct nfc_digital_dev *ddev, u8 rf_tech)
+{
+	struct digital_sensf_req *sensf_req;
+	struct sk_buff *skb;
+	int rc;
+	u8 size;
+
+	rc = digital_in_configure_hw(ddev, NFC_DIGITAL_CONFIG_RF_TECH, rf_tech);
+	if (rc)
+		return rc;
+
+	rc = digital_in_configure_hw(ddev, NFC_DIGITAL_CONFIG_FRAMING,
+				     NFC_DIGITAL_FRAMING_NFCF);
+	if (rc)
+		return rc;
+
+	size = sizeof(struct digital_sensf_req);
+
+	skb = digital_skb_alloc(ddev, size);
+	if (!skb)
+		return -ENOMEM;
+
+	skb_put(skb, size);
+
+	sensf_req = (struct digital_sensf_req *)skb->data;
+	sensf_req->cmd = DIGITAL_CMD_SENSF_REQ;
+	sensf_req->sc1 = 0xFF;
+	sensf_req->sc2 = 0xFF;
+	sensf_req->rc = 0;
+	sensf_req->tsn = 0;
+
+	*skb_push(skb, 1) = size + 1;
+
+	if (!DIGITAL_DRV_CAPS_IN_CRC(ddev))
+		digital_skb_add_crc_f(skb);
+
+	rc = digital_in_send_cmd(ddev, skb, 30, digital_in_recv_sensf_res,
+				 NULL);
+	if (rc)
+		kfree_skb(skb);
+
+	return rc;
+}