path: root/net/nfc/digital_dep.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * NFC Digital Protocol stack
 * Copyright (c) 2013, Intel Corporation.
 */

#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_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[];
} __packed;

struct digital_atr_res {
	u8 dir;
	u8 cmd;
	u8 nfcid3[10];
	u8 did;
	u8 bs;
	u8 br;
	u8 to;
	u8 pp;
	u8 gb[];
} __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 14
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];
}

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;
}

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)
		*(u8 *)skb_push(skb, sizeof(u8)) = DIGITAL_NFC_DEP_NFCA_SO