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1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * GeneSys GL620USB-A based links
4  * Copyright (C) 2001 by Jiun-Jie Huang <huangjj@genesyslogic.com.tw>
5  * Copyright (C) 2001 by Stanislav Brabec <utx@penguin.cz>
6  */
7 
8 // #define	DEBUG			// error path messages, extra info
9 // #define	VERBOSE			// more; success messages
10 
11 #include <linux/module.h>
12 #include <linux/netdevice.h>
13 #include <linux/etherdevice.h>
14 #include <linux/ethtool.h>
15 #include <linux/workqueue.h>
16 #include <linux/mii.h>
17 #include <linux/usb.h>
18 #include <linux/usb/usbnet.h>
19 #include <linux/gfp.h>
20 
21 
22 /*
23  * GeneSys GL620USB-A (www.genesyslogic.com.tw)
24  *
25  * ... should partially interop with the Win32 driver for this hardware.
26  * The GeneSys docs imply there's some NDIS issue motivating this framing.
27  *
28  * Some info from GeneSys:
29  *  - GL620USB-A is full duplex; GL620USB is only half duplex for bulk.
30  *    (Some cables, like the BAFO-100c, use the half duplex version.)
31  *  - For the full duplex model, the low bit of the version code says
32  *    which side is which ("left/right").
33  *  - For the half duplex type, a control/interrupt handshake settles
34  *    the transfer direction.  (That's disabled here, partially coded.)
35  *    A control URB would block until other side writes an interrupt.
36  *
37  * Original code from Jiun-Jie Huang <huangjj@genesyslogic.com.tw>
38  * and merged into "usbnet" by Stanislav Brabec <utx@penguin.cz>.
39  */
40 
41 // control msg write command
42 #define GENELINK_CONNECT_WRITE			0xF0
43 // interrupt pipe index
44 #define GENELINK_INTERRUPT_PIPE			0x03
45 // interrupt read buffer size
46 #define INTERRUPT_BUFSIZE			0x08
47 // interrupt pipe interval value
48 #define GENELINK_INTERRUPT_INTERVAL		0x10
49 // max transmit packet number per transmit
50 #define GL_MAX_TRANSMIT_PACKETS			32
51 // max packet length
52 #define GL_MAX_PACKET_LEN			1514
53 // max receive buffer size
54 #define GL_RCV_BUF_SIZE		\
55 	(((GL_MAX_PACKET_LEN + 4) * GL_MAX_TRANSMIT_PACKETS) + 4)
56 
57 struct gl_packet {
58 	__le32		packet_length;
59 	char		packet_data [1];
60 };
61 
62 struct gl_header {
63 	__le32			packet_count;
64 	struct gl_packet	packets;
65 };
66 
genelink_rx_fixup(struct usbnet * dev,struct sk_buff * skb)67 static int genelink_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
68 {
69 	struct gl_header	*header;
70 	struct gl_packet	*packet;
71 	struct sk_buff		*gl_skb;
72 	u32			size;
73 	u32			count;
74 
75 	/* This check is no longer done by usbnet */
76 	if (skb->len < dev->net->hard_header_len)
77 		return 0;
78 
79 	header = (struct gl_header *) skb->data;
80 
81 	// get the packet count of the received skb
82 	count = le32_to_cpu(header->packet_count);
83 	if (count > GL_MAX_TRANSMIT_PACKETS) {
84 		netdev_dbg(dev->net,
85 			   "genelink: invalid received packet count %u\n",
86 			   count);
87 		return 0;
88 	}
89 
90 	// set the current packet pointer to the first packet
91 	packet = &header->packets;
92 
93 	// decrement the length for the packet count size 4 bytes
94 	skb_pull(skb, 4);
95 
96 	while (count > 1) {
97 		// get the packet length
98 		size = le32_to_cpu(packet->packet_length);
99 
100 		// this may be a broken packet
101 		if (size > GL_MAX_PACKET_LEN) {
102 			netdev_dbg(dev->net, "genelink: invalid rx length %d\n",
103 				   size);
104 			return 0;
105 		}
106 
107 		// allocate the skb for the individual packet
108 		gl_skb = alloc_skb(size, GFP_ATOMIC);
109 		if (gl_skb) {
110 
111 			// copy the packet data to the new skb
112 			skb_put_data(gl_skb, packet->packet_data, size);
113 			usbnet_skb_return(dev, gl_skb);
114 		}
115 
116 		// advance to the next packet
117 		packet = (struct gl_packet *)&packet->packet_data[size];
118 		count--;
119 
120 		// shift the data pointer to the next gl_packet
121 		skb_pull(skb, size + 4);
122 	}
123 
124 	// skip the packet length field 4 bytes
125 	skb_pull(skb, 4);
126 
127 	if (skb->len > GL_MAX_PACKET_LEN) {
128 		netdev_dbg(dev->net, "genelink: invalid rx length %d\n",
129 			   skb->len);
130 		return 0;
131 	}
132 	return 1;
133 }
134 
135 static struct sk_buff *
genelink_tx_fixup(struct usbnet * dev,struct sk_buff * skb,gfp_t flags)136 genelink_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
137 {
138 	int 	padlen;
139 	int	length = skb->len;
140 	int	headroom = skb_headroom(skb);
141 	int	tailroom = skb_tailroom(skb);
142 	__le32	*packet_count;
143 	__le32	*packet_len;
144 
145 	// FIXME:  magic numbers, bleech
146 	padlen = ((skb->len + (4 + 4*1)) % 64) ? 0 : 1;
147 
148 	if ((!skb_cloned(skb))
149 			&& ((headroom + tailroom) >= (padlen + (4 + 4*1)))) {
150 		if ((headroom < (4 + 4*1)) || (tailroom < padlen)) {
151 			skb->data = memmove(skb->head + (4 + 4*1),
152 					     skb->data, skb->len);
153 			skb_set_tail_pointer(skb, skb->len);
154 		}
155 	} else {
156 		struct sk_buff	*skb2;
157 		skb2 = skb_copy_expand(skb, (4 + 4*1) , padlen, flags);
158 		dev_kfree_skb_any(skb);
159 		skb = skb2;
160 		if (!skb)
161 			return NULL;
162 	}
163 
164 	// attach the packet count to the header
165 	packet_count = skb_push(skb, (4 + 4 * 1));
166 	packet_len = packet_count + 1;
167 
168 	*packet_count = cpu_to_le32(1);
169 	*packet_len = cpu_to_le32(length);
170 
171 	// add padding byte
172 	if ((skb->len % dev->maxpacket) == 0)
173 		skb_put(skb, 1);
174 
175 	return skb;
176 }
177 
genelink_bind(struct usbnet * dev,struct usb_interface * intf)178 static int genelink_bind(struct usbnet *dev, struct usb_interface *intf)
179 {
180 	dev->hard_mtu = GL_RCV_BUF_SIZE;
181 	dev->net->hard_header_len += 4;
182 	dev->in = usb_rcvbulkpipe(dev->udev, dev->driver_info->in);
183 	dev->out = usb_sndbulkpipe(dev->udev, dev->driver_info->out);
184 	return 0;
185 }
186 
187 static const struct driver_info	genelink_info = {
188 	.description =	"Genesys GeneLink",
189 	.flags =	FLAG_POINTTOPOINT | FLAG_FRAMING_GL | FLAG_NO_SETINT,
190 	.bind =		genelink_bind,
191 	.rx_fixup =	genelink_rx_fixup,
192 	.tx_fixup =	genelink_tx_fixup,
193 
194 	.in = 1, .out = 2,
195 
196 #ifdef	GENELINK_ACK
197 	.check_connect =genelink_check_connect,
198 #endif
199 };
200 
201 static const struct usb_device_id	products [] = {
202 
203 {
204 	USB_DEVICE(0x05e3, 0x0502),	// GL620USB-A
205 	.driver_info =	(unsigned long) &genelink_info,
206 },
207 	/* NOT: USB_DEVICE(0x05e3, 0x0501),	// GL620USB
208 	 * that's half duplex, not currently supported
209 	 */
210 	{ },		// END
211 };
212 MODULE_DEVICE_TABLE(usb, products);
213 
214 static struct usb_driver gl620a_driver = {
215 	.name =		"gl620a",
216 	.id_table =	products,
217 	.probe =	usbnet_probe,
218 	.disconnect =	usbnet_disconnect,
219 	.suspend =	usbnet_suspend,
220 	.resume =	usbnet_resume,
221 	.disable_hub_initiated_lpm = 1,
222 };
223 
224 module_usb_driver(gl620a_driver);
225 
226 MODULE_AUTHOR("Jiun-Jie Huang");
227 MODULE_DESCRIPTION("GL620-USB-A Host-to-Host Link cables");
228 MODULE_LICENSE("GPL");
229 
230