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NFC Digital: Add NFC-F technology support
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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>
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Thierry Escande authored and Samuel Ortiz committed Sep 25, 2013
1 parent 2c66dae commit 8c0695e
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1 change: 1 addition & 0 deletions net/nfc/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down
13 changes: 13 additions & 0 deletions net/nfc/digital.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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__)
Expand Down Expand Up @@ -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);
Expand All @@ -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);
Expand All @@ -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;
Expand All @@ -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;
Expand Down
18 changes: 18 additions & 0 deletions net/nfc/digital_core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;

Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;
Expand Down
121 changes: 121 additions & 0 deletions net/nfc/digital_technology.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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);

Expand Down Expand Up @@ -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;
}

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