1/*
2 *	LAPB release 002
3 *
4 *	This code REQUIRES 2.1.15 or higher/ NET3.038
5 *
6 *	This module:
7 *		This module is free software; you can redistribute it and/or
8 *		modify it under the terms of the GNU General Public License
9 *		as published by the Free Software Foundation; either version
10 *		2 of the License, or (at your option) any later version.
11 *
12 *	History
13 *	LAPB 001	Jonathan Naylor	Started Coding
14 *	LAPB 002	Jonathan Naylor	New timer architecture.
15 */
16
17#include <linux/errno.h>
18#include <linux/types.h>
19#include <linux/socket.h>
20#include <linux/in.h>
21#include <linux/kernel.h>
22#include <linux/timer.h>
23#include <linux/string.h>
24#include <linux/sockios.h>
25#include <linux/net.h>
26#include <linux/inet.h>
27#include <linux/skbuff.h>
28#include <net/sock.h>
29#include <asm/uaccess.h>
30#include <asm/system.h>
31#include <linux/fcntl.h>
32#include <linux/mm.h>
33#include <linux/interrupt.h>
34#include <net/lapb.h>
35
36/*
37 *  This procedure is passed a buffer descriptor for an iframe. It builds
38 *  the rest of the control part of the frame and then writes it out.
39 */
40static void lapb_send_iframe(struct lapb_cb *lapb, struct sk_buff *skb, int poll_bit)
41{
42	unsigned char *frame;
43
44	if (!skb)
45		return;
46
47	if (lapb->mode & LAPB_EXTENDED) {
48		frame = skb_push(skb, 2);
49
50		frame[0] = LAPB_I;
51		frame[0] |= lapb->vs << 1;
52		frame[1] = poll_bit ? LAPB_EPF : 0;
53		frame[1] |= lapb->vr << 1;
54	} else {
55		frame = skb_push(skb, 1);
56
57		*frame = LAPB_I;
58		*frame |= poll_bit ? LAPB_SPF : 0;
59		*frame |= lapb->vr << 5;
60		*frame |= lapb->vs << 1;
61	}
62
63#if LAPB_DEBUG > 1
64	printk(KERN_DEBUG "lapb: (%p) S%d TX I(%d) S%d R%d\n",
65	       lapb->dev, lapb->state, poll_bit, lapb->vs, lapb->vr);
66#endif
67
68	lapb_transmit_buffer(lapb, skb, LAPB_COMMAND);
69}
70
71void lapb_kick(struct lapb_cb *lapb)
72{
73	struct sk_buff *skb, *skbn;
74	unsigned short modulus, start, end;
75
76	modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
77	start = !skb_peek(&lapb->ack_queue) ? lapb->va : lapb->vs;
78	end   = (lapb->va + lapb->window) % modulus;
79
80	if (!(lapb->condition & LAPB_PEER_RX_BUSY_CONDITION) &&
81	    start != end && skb_peek(&lapb->write_queue)) {
82		lapb->vs = start;
83
84		/*
85		 * Dequeue the frame and copy it.
86		 */
87		skb = skb_dequeue(&lapb->write_queue);
88
89		do {
90			if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
91				skb_queue_head(&lapb->write_queue, skb);
92				break;
93			}
94
95			if (skb->sk)
96				skb_set_owner_w(skbn, skb->sk);
97
98			/*
99			 * Transmit the frame copy.
100			 */
101			lapb_send_iframe(lapb, skbn, LAPB_POLLOFF);
102
103			lapb->vs = (lapb->vs + 1) % modulus;
104
105			/*
106			 * Requeue the original data frame.
107			 */
108			skb_queue_tail(&lapb->ack_queue, skb);
109
110		} while (lapb->vs != end && (skb = skb_dequeue(&lapb->write_queue)) != NULL);
111
112		lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
113
114		if (!lapb_t1timer_running(lapb))
115			lapb_start_t1timer(lapb);
116	}
117}
118
119void lapb_transmit_buffer(struct lapb_cb *lapb, struct sk_buff *skb, int type)
120{
121	unsigned char *ptr;
122
123	ptr = skb_push(skb, 1);
124
125	if (lapb->mode & LAPB_MLP) {
126		if (lapb->mode & LAPB_DCE) {
127			if (type == LAPB_COMMAND)
128				*ptr = LAPB_ADDR_C;
129			if (type == LAPB_RESPONSE)
130				*ptr = LAPB_ADDR_D;
131		} else {
132			if (type == LAPB_COMMAND)
133				*ptr = LAPB_ADDR_D;
134			if (type == LAPB_RESPONSE)
135				*ptr = LAPB_ADDR_C;
136		}
137	} else {
138		if (lapb->mode & LAPB_DCE) {
139			if (type == LAPB_COMMAND)
140				*ptr = LAPB_ADDR_A;
141			if (type == LAPB_RESPONSE)
142				*ptr = LAPB_ADDR_B;
143		} else {
144			if (type == LAPB_COMMAND)
145				*ptr = LAPB_ADDR_B;
146			if (type == LAPB_RESPONSE)
147				*ptr = LAPB_ADDR_A;
148		}
149	}
150
151#if LAPB_DEBUG > 2
152	printk(KERN_DEBUG "lapb: (%p) S%d TX %02X %02X %02X\n",
153	       lapb->dev, lapb->state,
154	       skb->data[0], skb->data[1], skb->data[2]);
155#endif
156
157	if (!lapb_data_transmit(lapb, skb))
158		kfree_skb(skb);
159}
160
161void lapb_establish_data_link(struct lapb_cb *lapb)
162{
163	lapb->condition = 0x00;
164	lapb->n2count   = 0;
165
166	if (lapb->mode & LAPB_EXTENDED) {
167#if LAPB_DEBUG > 1
168		printk(KERN_DEBUG "lapb: (%p) S%d TX SABME(1)\n",
169		       lapb->dev, lapb->state);
170#endif
171		lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
172	} else {
173#if LAPB_DEBUG > 1
174		printk(KERN_DEBUG "lapb: (%p) S%d TX SABM(1)\n",
175		       lapb->dev, lapb->state);
176#endif
177		lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
178	}
179
180	lapb_start_t1timer(lapb);
181	lapb_stop_t2timer(lapb);
182}
183
184void lapb_enquiry_response(struct lapb_cb *lapb)
185{
186#if LAPB_DEBUG > 1
187	printk(KERN_DEBUG "lapb: (%p) S%d TX RR(1) R%d\n",
188	       lapb->dev, lapb->state, lapb->vr);
189#endif
190
191	lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE);
192
193	lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
194}
195
196void lapb_timeout_response(struct lapb_cb *lapb)
197{
198#if LAPB_DEBUG > 1
199	printk(KERN_DEBUG "lapb: (%p) S%d TX RR(0) R%d\n",
200	       lapb->dev, lapb->state, lapb->vr);
201#endif
202	lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE);
203
204	lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
205}
206
207void lapb_check_iframes_acked(struct lapb_cb *lapb, unsigned short nr)
208{
209	if (lapb->vs == nr) {
210		lapb_frames_acked(lapb, nr);
211		lapb_stop_t1timer(lapb);
212		lapb->n2count = 0;
213	} else if (lapb->va != nr) {
214		lapb_frames_acked(lapb, nr);
215		lapb_start_t1timer(lapb);
216	}
217}
218
219void lapb_check_need_response(struct lapb_cb *lapb, int type, int pf)
220{
221	if (type == LAPB_COMMAND && pf)
222		lapb_enquiry_response(lapb);
223}
224