cregit-Linux how code gets into the kernel

Release 4.8 net/nfc/digital_dep.c

Directory: net/nfc
/*
 * NFC Digital Protocol stack
 * Copyright (c) 2013, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 */


#define pr_fmt(fmt) "digital: %s: " fmt, __func__

#include "digital.h"


#define DIGITAL_NFC_DEP_N_RETRY_NACK	2

#define DIGITAL_NFC_DEP_N_RETRY_ATN	2


#define DIGITAL_NFC_DEP_FRAME_DIR_OUT 0xD4

#define DIGITAL_NFC_DEP_FRAME_DIR_IN  0xD5


#define DIGITAL_NFC_DEP_NFCA_SOD_SB   0xF0


#define DIGITAL_CMD_ATR_REQ 0x00

#define DIGITAL_CMD_ATR_RES 0x01

#define DIGITAL_CMD_PSL_REQ 0x04

#define DIGITAL_CMD_PSL_RES 0x05

#define DIGITAL_CMD_DEP_REQ 0x06

#define DIGITAL_CMD_DEP_RES 0x07


#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

#define DIGITAL_PAYLOAD_BITS_TO_PP(s)	(((s) & 0x3) << 4)

#define DIGITAL_PAYLOAD_PP_TO_BITS(s)	(((s) >> 4) & 0x3)

#define DIGITAL_PAYLOAD_BITS_TO_FSL(s)	((s) & 0x3)

#define DIGITAL_PAYLOAD_FSL_TO_BITS(s)	((s) & 0x3)


#define DIGITAL_GB_BIT	0x02


#define DIGITAL_NFC_DEP_REQ_RES_HEADROOM	2 
/* SoD: [SB (NFC-A)] + LEN */

#define DIGITAL_NFC_DEP_REQ_RES_TAILROOM	2 
/* EoD: 2-byte CRC */


#define DIGITAL_NFC_DEP_PFB_TYPE(pfb) ((pfb) & 0xE0)


#define DIGITAL_NFC_DEP_PFB_TIMEOUT_BIT 0x10

#define DIGITAL_NFC_DEP_PFB_MI_BIT	0x10

#define DIGITAL_NFC_DEP_PFB_NACK_BIT	0x10

#define DIGITAL_NFC_DEP_PFB_DID_BIT	0x04


#define DIGITAL_NFC_DEP_PFB_IS_TIMEOUT(pfb) \
				((pfb) & DIGITAL_NFC_DEP_PFB_TIMEOUT_BIT)

#define DIGITAL_NFC_DEP_MI_BIT_SET(pfb)  ((pfb) & DIGITAL_NFC_DEP_PFB_MI_BIT)

#define DIGITAL_NFC_DEP_NACK_BIT_SET(pfb) ((pfb) & DIGITAL_NFC_DEP_PFB_NACK_BIT)

#define DIGITAL_NFC_DEP_NAD_BIT_SET(pfb) ((pfb) & 0x08)

#define DIGITAL_NFC_DEP_DID_BIT_SET(pfb) ((pfb) & DIGITAL_NFC_DEP_PFB_DID_BIT)

#define DIGITAL_NFC_DEP_PFB_PNI(pfb)     ((pfb) & 0x03)


#define DIGITAL_NFC_DEP_RTOX_VALUE(data) ((data) & 0x3F)

#define DIGITAL_NFC_DEP_RTOX_MAX	 59


#define DIGITAL_NFC_DEP_PFB_I_PDU          0x00

#define DIGITAL_NFC_DEP_PFB_ACK_NACK_PDU   0x40

#define DIGITAL_NFC_DEP_PFB_SUPERVISOR_PDU 0x80


struct digital_atr_req {
	
u8 dir;
	
u8 cmd;
	
u8 nfcid3[10];
	
u8 did;
	
u8 bs;
	
u8 br;
	
u8 pp;
	
u8 gb[0];
} 
__packed;


struct digital_atr_res {
	
u8 dir;
	
u8 cmd;
	
u8 nfcid3[10];
	
u8 did;
	
u8 bs;
	
u8 br;
	
u8 to;
	
u8 pp;
	
u8 gb[0];
} 
__packed;


struct digital_psl_req {
	
u8 dir;
	
u8 cmd;
	
u8 did;
	
u8 brs;
	
u8 fsl;
} 
__packed;


struct digital_psl_res {
	
u8 dir;
	
u8 cmd;
	
u8 did;
} 
__packed;


struct digital_dep_req_res {
	
u8 dir;
	
u8 cmd;
	
u8 pfb;
} 
__packed;

static void digital_in_recv_dep_res(struct nfc_digital_dev *ddev, void *arg,
				    struct sk_buff *resp);
static void digital_tg_recv_dep_req(struct nfc_digital_dev *ddev, void *arg,
				    struct sk_buff *resp);


static const u8 digital_payload_bits_map[4] = {
	[0] = 64,
	[1] = 128,
	[2] = 192,
	[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)) return 0; return digital_payload_bits_map[payload_bits]; }

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static u8 digital_payload_size_to_bits(u8 payload_size) { int i; for (i = 0; i < ARRAY_SIZE(digital_payload_bits_map); i++) if (digital_payload_bits_map[i] == payload_size) return i; return 0xff; }

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static void digital_skb_push_dep_sod(struct nfc_digital_dev *ddev, struct sk_buff *skb) { skb_push(skb, sizeof(u8)); skb->data[0] = skb->len; if (ddev->curr_rf_tech == NFC_DIGITAL_RF_TECH_106A) *skb_push(skb, sizeof(u8)) = DIGITAL_NFC_DEP_NFCA_SOD_SB; }

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static int digital_skb_pull_dep_sod(struct nfc_digital_dev *ddev, struct sk_buff *skb) { u8 size; if (skb->len < 2) return -EIO; if (ddev->curr_rf_tech == NFC_DIGITAL_RF_TECH_106A) skb_pull(skb, sizeof(u8)); size = skb->data[0]; if (size != skb->len) return -EIO; skb_pull(skb, sizeof(u8)); return 0; }

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static struct sk_buff * digital_send_dep_data_prep(struct nfc_digital_dev *ddev, struct sk_buff *skb, struct digital_dep_req_res *dep_req_res, struct digital_data_exch *data_exch) { struct sk_buff *new_skb; if (skb->len > ddev->remote_payload_max) { dep_req_res->pfb |= DIGITAL_NFC_DEP_PFB_MI_BIT; new_skb = digital_skb_alloc(ddev, ddev->remote_payload_max); if (!new_skb) { kfree_skb(ddev->chaining_skb); ddev->chaining_skb = NULL; return ERR_PTR(-ENOMEM); } memcpy(skb_put(new_skb, ddev->remote_payload_max), skb->data, ddev->remote_payload_max); skb_pull(skb, ddev->remote_payload_max); ddev->chaining_skb = skb; ddev->data_exch = data_exch; } else { ddev->chaining_skb = NULL; new_skb = skb; } return new_skb; }

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static struct sk_buff * digital_recv_dep_data_gather(struct nfc_digital_dev *ddev, u8 pfb, struct sk_buff *resp, int (*send_ack)(struct nfc_digital_dev *ddev, struct digital_data_exch *data_exch), struct digital_data_exch *data_exch) { struct sk_buff *new_skb; int rc; if (DIGITAL_NFC_DEP_MI_BIT_SET(pfb) && (!ddev->chaining_skb)) { ddev->chaining_skb = nfc_alloc_recv_skb(8 * ddev->local_payload_max, GFP_KERNEL); if (!ddev->chaining_skb) { rc = -ENOMEM; goto error; } } if (ddev->chaining_skb) { if (resp->len > skb_tailroom(ddev->chaining_skb)) { new_skb = skb_copy_expand(ddev->chaining_skb, skb_headroom( ddev->chaining_skb), 8 * ddev->local_payload_max, GFP_KERNEL); if (!new_skb) { rc = -ENOMEM; goto error; } kfree_skb(ddev->chaining_skb); ddev->chaining_skb = new_skb; } memcpy(skb_put(ddev->chaining_skb, resp->len), resp->data, resp->len); kfree_skb(resp); resp = NULL; if (DIGITAL_NFC_DEP_MI_BIT_SET(pfb)) { rc = send_ack(ddev, data_exch); if (rc) goto error; return NULL; } resp = ddev->chaining_skb; ddev->chaining_skb = NULL; } return resp; error: kfree_skb(resp); kfree_skb(ddev->chaining_skb); ddev->chaining_skb = NULL; return ERR_PTR(rc); }

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static void digital_in_recv_psl_res(struct nfc_digital_dev *ddev, void *arg, struct sk_buff *resp) { struct nfc_target *target = arg; struct digital_psl_res *psl_res; int rc; if (IS_ERR(resp)) { rc = PTR_ERR(resp); resp = NULL; goto exit; } rc = ddev->skb_check_crc(resp); if (rc) { PROTOCOL_ERR("14.4.1.6"); goto exit; } rc = digital_skb_pull_dep_sod(ddev, resp); if (rc) { PROTOCOL_ERR("14.4.1.2"); goto exit; } psl_res = (struct digital_psl_res *)resp->data; if ((resp->len != sizeof(*psl_res)) || (psl_res->dir != DIGITAL_NFC_DEP_FRAME_DIR_IN) || (psl_res->cmd != DIGITAL_CMD_PSL_RES)) { rc = -EIO; goto exit; } rc = digital_in_configure_hw(ddev, NFC_DIGITAL_CONFIG_RF_TECH, NFC_DIGITAL_RF_TECH_424F); if (rc) goto exit; rc = digital_in_configure_hw(ddev, NFC_DIGITAL_CONFIG_FRAMING, NFC_DIGITAL_FRAMING_NFCF_NFC_DEP); if (rc) goto exit; if (!DIGITAL_DRV_CAPS_IN_CRC(ddev) && (ddev->curr_rf_tech == NFC_DIGITAL_RF_TECH_106A)) { ddev->skb_add_crc = digital_skb_add_crc_f; ddev->skb_check_crc = digital_skb_check_crc_f; } ddev->curr_rf_tech = NFC_DIGITAL_RF_TECH_424F; nfc_dep_link_is_up(ddev->nfc_dev, target->idx, NFC_COMM_ACTIVE, NFC_RF_INITIATOR); ddev->curr_nfc_dep_pni = 0; exit: dev_kfree_skb(resp); if (rc) ddev->curr_protocol = 0; }

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static int digital_in_send_psl_req(struct nfc_digital_dev *ddev, struct nfc_target *target) { struct sk_buff *skb; struct digital_psl_req *psl_req; int rc; u8 payload_size, payload_bits; skb = digital_skb_alloc(ddev, sizeof(*psl_req)); if (!skb) return -ENOMEM; skb_put(skb, sizeof(*psl_req)); psl_req = (struct digital_psl_req *)skb->data; psl_req->dir = DIGITAL_NFC_DEP_FRAME_DIR_OUT; psl_req->cmd = DIGITAL_CMD_PSL_REQ; psl_req->did = 0; psl_req->brs = (0x2 << 3) | 0x2; /* 424F both directions */ payload_size = min(ddev->local_payload_max, ddev->remote_payload_max); payload_bits = digital_payload_size_to_bits(payload_size); psl_req->fsl = DIGITAL_PAYLOAD_BITS_TO_FSL(payload_bits); ddev->local_payload_max = payload_size; ddev->remote_payload_max = payload_size; digital_skb_push_dep_sod(ddev, skb); ddev->skb_add_crc(skb); rc = digital_in_send_cmd(ddev, skb, ddev->dep_rwt, digital_in_recv_psl_res, target); if (rc) kfree_skb(skb); return rc; }

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static void digital_in_recv_atr_res(struct nfc_digital_dev *ddev, void *arg, struct sk_buff *resp) { struct nfc_target *target = arg; struct digital_atr_res *atr_res; u8 gb_len, payload_bits; u8 wt; int rc; if (IS_ERR(resp)) { rc = PTR_ERR(resp); resp = NULL; goto exit; } rc = ddev->skb_check_crc(resp); if (rc) { PROTOCOL_ERR("14.4.1.6"); goto exit; } rc = digital_skb_pull_dep_sod(ddev, resp); if (rc) { PROTOCOL_ERR("14.4.1.2"); goto exit; } if (resp->len < sizeof(struct digital_atr_res)) { rc = -EIO; goto exit; } gb_len = resp->len - sizeof(struct digital_atr_res); 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); if (!ddev->remote_payload_max) { rc = -EINVAL; goto exit; } rc = nfc_set_remote_general_bytes(ddev->nfc_dev, atr_res->gb, gb_len); if (rc) goto exit; if ((ddev->protocols & NFC_PROTO_FELICA_MASK) && (ddev->curr_rf_tech != NFC_DIGITAL_RF_TECH_424F)) { rc = digital_in_send_psl_req(ddev, target); if (!rc) goto exit; } rc = nfc_dep_link_is_up(ddev->nfc_dev, target->idx, NFC_COMM_ACTIVE, NFC_RF_INITIATOR); ddev->curr_nfc_dep_pni = 0; exit: dev_kfree_skb(resp); if (rc) ddev->curr_protocol = 0; }

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int digital_in_send_atr_req(struct nfc_digital_dev *ddev, struct nfc_target *target, __u8 comm_mode, __u8 *gb, size_t gb_len) { struct sk_buff *skb; struct digital_atr_req *atr_req; uint size; int rc; u8 payload_bits; size = DIGITAL_ATR_REQ_MIN_SIZE + gb_len; if (size > DIGITAL_ATR_REQ_MAX_SIZE) { PROTOCOL_ERR("14.6.1.1"); return -EINVAL; } skb = digital_skb_alloc(ddev, size); if (!skb) return -ENOMEM; skb_put(skb, sizeof(struct digital_atr_req)); atr_req = (struct digital_atr_req *)skb->data; memset(atr_req, 0, sizeof(struct digital_atr_req)); atr_req->dir = DIGITAL_NFC_DEP_FRAME_DIR_OUT; atr_req->cmd = DIGITAL_CMD_ATR_REQ; if (target->nfcid2_len) memcpy(atr_req->nfcid3, target->nfcid2, NFC_NFCID2_MAXSIZE); else get_random_bytes(atr_req->nfcid3, NFC_NFCID3_MAXSIZE); atr_req->did = 0; atr_req->bs = 0; atr_req->br = 0; ddev->local_payload_max = DIGITAL_PAYLOAD_SIZE_MAX; payload_bits = digital_payload_size_to_bits(ddev->local_payload_max); atr_req->pp = DIGITAL_PAYLOAD_BITS_TO_PP(payload_bits); if (gb_len) { atr_req->pp |= DIGITAL_GB_BIT; memcpy(skb_put(skb, gb_len), gb, gb_len); } digital_skb_push_dep_sod(ddev, skb); ddev->skb_add_crc(skb); rc = digital_in_send_cmd(ddev, skb, DIGITAL_ATR_RES_RWT, digital_in_recv_atr_res, target); if (rc) kfree_skb(skb); return rc; }

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static int digital_in_send_ack(struct nfc_digital_dev *ddev, struct digital_data_exch *data_exch) { struct digital_dep_req_res *dep_req; struct sk_buff *skb; int rc; skb = digital_skb_alloc(ddev, 1); if (!skb) return -ENOMEM; skb_push(skb, sizeof(struct digital_dep_req_res)); dep_req = (struct digital_dep_req_res *)skb->data; dep_req->dir = DIGITAL_NFC_DEP_FRAME_DIR_OUT; dep_req->cmd = DIGITAL_CMD_DEP_REQ; dep_req->pfb = DIGITAL_NFC_DEP_PFB_ACK_NACK_PDU | ddev->curr_nfc_dep_pni; digital_skb_push_dep_sod(ddev, skb); ddev->skb_add_crc(skb); ddev->saved_skb = pskb_copy(skb, GFP_KERNEL); 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); ddev->saved_skb = NULL; } return rc; }

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static int digital_in_send_nack(struct nfc_digital_dev *ddev, struct digital_data_exch *data_exch) { struct digital_dep_req_res *dep_req; struct sk_buff *skb; int rc; skb = digital_skb_alloc(ddev, 1); if (!skb) return -ENOMEM; skb_push(skb, sizeof(struct digital_dep_req_res)); dep_req = (struct digital_dep_req_res *)skb->data; dep_req->dir = DIGITAL_NFC_DEP_FRAME_DIR_OUT; dep_req->cmd = DIGITAL_CMD_DEP_REQ; dep_req->pfb = DIGITAL_NFC_DEP_PFB_ACK_NACK_PDU | DIGITAL_NFC_DEP_PFB_NACK_BIT | ddev->curr_nfc_dep_pni; digital_skb_push_dep_sod(ddev, skb); ddev->skb_add_crc(skb); rc = digital_in_send_cmd(ddev, skb, ddev->dep_rwt, digital_in_recv_dep_res, data_exch); if (rc) kfree_skb(skb); return rc; }

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static int digital_in_send_atn(struct nfc_digital_dev *ddev, struct digital_data_exch *data_exch) { struct digital_dep_req_res *dep_req; struct sk_buff *skb; int rc; skb = digital_skb_alloc(ddev, 1); if (!skb) return -ENOMEM; skb_push(skb, sizeof(struct digital_dep_req_res)); dep_req = (struct digital_dep_req_res *)skb->data; dep_req->dir = DIGITAL_NFC_DEP_FRAME_DIR_OUT; dep_req->cmd = DIGITAL_CMD_DEP_REQ; dep_req->pfb = DIGITAL_NFC_DEP_PFB_SUPERVISOR_PDU; digital_skb_push_dep_sod(ddev, skb); ddev->skb_add_crc(skb); rc = digital_in_send_cmd(ddev, skb, ddev->dep_rwt, digital_in_recv_dep_res, data_exch); if (rc) kfree_skb(skb); return rc; }

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static int digital_in_send_rtox(struct nfc_digital_dev *ddev, struct digital_data_exch *data_exch, u8 rtox) { struct digital_dep_req_res *dep_req; struct sk_buff *skb; int rc; u16 rwt_int; rwt_int = ddev->dep_rwt * rtox; if (rwt_int > digital_rwt_map[DIGITAL_NFC_DEP_IN_MAX_WT]) rwt_int = digital_rwt_map[DIGITAL_NFC_DEP_IN_MAX_WT]; skb = digital_skb_alloc(ddev, 1); if (!skb) return -ENOMEM; *skb_put(skb, 1) = rtox; skb_push(skb, sizeof(struct digital_dep_req_res)); dep_req = (struct digital_dep_req_res *)skb->data; dep_req->dir = DIGITAL_NFC_DEP_FRAME_DIR_OUT; dep_req->cmd = DIGITAL_CMD_DEP_REQ; dep_req->pfb = DIGITAL_NFC_DEP_PFB_SUPERVISOR_PDU | DIGITAL_NFC_DEP_PFB_TIMEOUT_BIT; digital_skb_push_dep_sod(ddev, skb); ddev->skb_add_crc(skb); rc = digital_in_send_cmd(ddev, skb, rwt_int, digital_in_recv_dep_res, data_exch); if (rc) kfree_skb(skb); return rc; }

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static int digital_in_send_saved_skb(struct nfc_digital_dev *ddev, struct digital_data_exch *data_exch) { int rc; if (!ddev->saved_skb) return -EINVAL; skb_get(ddev->saved_skb); 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); return rc; }

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static void digital_in_recv_dep_res(struct nfc_digital_dev *ddev, void *arg, struct sk_buff *resp) { struct digital_data_exch *data_exch = arg; struct digital_dep_req_res *dep_res; u8 pfb; uint size; int rc; u8 rtox; if (IS_ERR(resp)) { rc = PTR_ERR(resp); resp = NULL; if ((rc == -EIO || (rc