1 /*
2  * Driver for RobotFuzz OSIF
3  *
4  * Copyright (c) 2013 Andrew Lunn <andrew@lunn.ch>
5  * Copyright (c) 2007 Barry Carter <Barry.Carter@robotfuzz.com>
6  *
7  * Based on the i2c-tiny-usb by
8  *
9  * Copyright (C) 2006 Til Harbaum (Till@Harbaum.org)
10  *
11  *	This program is free software; you can redistribute it and/or
12  *	modify it under the terms of the GNU General Public License as
13  *	published by the Free Software Foundation, version 2.
14  */
15 
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/errno.h>
19 #include <linux/i2c.h>
20 #include <linux/slab.h>
21 #include <linux/usb.h>
22 
23 #define OSIFI2C_READ		20
24 #define OSIFI2C_WRITE		21
25 #define OSIFI2C_STOP		22
26 #define OSIFI2C_STATUS		23
27 #define OSIFI2C_SET_BIT_RATE	24
28 
29 #define STATUS_ADDRESS_ACK	0
30 #define STATUS_ADDRESS_NAK	2
31 
32 struct osif_priv {
33 	struct usb_device *usb_dev;
34 	struct usb_interface *interface;
35 	struct i2c_adapter adapter;
36 	unsigned char status;
37 };
38 
39 static int osif_usb_read(struct i2c_adapter *adapter, int cmd,
40 			 int value, int index, void *data, int len)
41 {
42 	struct osif_priv *priv = adapter->algo_data;
43 
44 	return usb_control_msg(priv->usb_dev, usb_rcvctrlpipe(priv->usb_dev, 0),
45 			       cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
46 			       USB_DIR_IN, value, index, data, len, 2000);
47 }
48 
49 static int osif_usb_write(struct i2c_adapter *adapter, int cmd,
50 			  int value, int index, void *data, int len)
51 {
52 
53 	struct osif_priv *priv = adapter->algo_data;
54 
55 	return usb_control_msg(priv->usb_dev, usb_sndctrlpipe(priv->usb_dev, 0),
56 			       cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
57 			       value, index, data, len, 2000);
58 }
59 
60 static int osif_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
61 			 int num)
62 {
63 	struct osif_priv *priv = adapter->algo_data;
64 	struct i2c_msg *pmsg;
65 	int ret = 0;
66 	int i, cmd;
67 
68 	for (i = 0; ret >= 0 && i < num; i++) {
69 		pmsg = &msgs[i];
70 
71 		if (pmsg->flags & I2C_M_RD) {
72 			cmd = OSIFI2C_READ;
73 
74 			ret = osif_usb_read(adapter, cmd, pmsg->flags,
75 					    pmsg->addr, pmsg->buf,
76 					    pmsg->len);
77 			if (ret != pmsg->len) {
78 				dev_err(&adapter->dev, "failure reading data\n");
79 				return -EREMOTEIO;
80 			}
81 		} else {
82 			cmd = OSIFI2C_WRITE;
83 
84 			ret = osif_usb_write(adapter, cmd, pmsg->flags,
85 					     pmsg->addr, pmsg->buf, pmsg->len);
86 			if (ret != pmsg->len) {
87 				dev_err(&adapter->dev, "failure writing data\n");
88 				return -EREMOTEIO;
89 			}
90 		}
91 
92 		ret = osif_usb_read(adapter, OSIFI2C_STOP, 0, 0, NULL, 0);
93 		if (ret) {
94 			dev_err(&adapter->dev, "failure sending STOP\n");
95 			return -EREMOTEIO;
96 		}
97 
98 		/* read status */
99 		ret = osif_usb_read(adapter, OSIFI2C_STATUS, 0, 0,
100 				    &priv->status, 1);
101 		if (ret != 1) {
102 			dev_err(&adapter->dev, "failure reading status\n");
103 			return -EREMOTEIO;
104 		}
105 
106 		if (priv->status != STATUS_ADDRESS_ACK) {
107 			dev_dbg(&adapter->dev, "status = %d\n", priv->status);
108 			return -EREMOTEIO;
109 		}
110 	}
111 
112 	return i;
113 }
114 
115 static u32 osif_func(struct i2c_adapter *adapter)
116 {
117 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
118 }
119 
120 static struct i2c_algorithm osif_algorithm = {
121 	.master_xfer	= osif_xfer,
122 	.functionality	= osif_func,
123 };
124 
125 #define USB_OSIF_VENDOR_ID	0x1964
126 #define USB_OSIF_PRODUCT_ID	0x0001
127 
128 static struct usb_device_id osif_table[] = {
129 	{ USB_DEVICE(USB_OSIF_VENDOR_ID, USB_OSIF_PRODUCT_ID) },
130 	{ }
131 };
132 MODULE_DEVICE_TABLE(usb, osif_table);
133 
134 static int osif_probe(struct usb_interface *interface,
135 			     const struct usb_device_id *id)
136 {
137 	int ret;
138 	struct osif_priv *priv;
139 	u16 version;
140 
141 	priv = devm_kzalloc(&interface->dev, sizeof(*priv), GFP_KERNEL);
142 	if (!priv)
143 		return -ENOMEM;
144 
145 	priv->usb_dev = usb_get_dev(interface_to_usbdev(interface));
146 	priv->interface = interface;
147 
148 	usb_set_intfdata(interface, priv);
149 
150 	priv->adapter.owner = THIS_MODULE;
151 	priv->adapter.class = I2C_CLASS_HWMON;
152 	priv->adapter.algo = &osif_algorithm;
153 	priv->adapter.algo_data = priv;
154 	snprintf(priv->adapter.name, sizeof(priv->adapter.name),
155 		 "OSIF at bus %03d device %03d",
156 		 priv->usb_dev->bus->busnum, priv->usb_dev->devnum);
157 
158 	/*
159 	 * Set bus frequency. The frequency is:
160 	 * 120,000,000 / ( 16 + 2 * div * 4^prescale).
161 	 * Using dev = 52, prescale = 0 give 100KHz */
162 	ret = osif_usb_read(&priv->adapter, OSIFI2C_SET_BIT_RATE, 52, 0,
163 			    NULL, 0);
164 	if (ret) {
165 		dev_err(&interface->dev, "failure sending bit rate");
166 		usb_put_dev(priv->usb_dev);
167 		return ret;
168 	}
169 
170 	i2c_add_adapter(&(priv->adapter));
171 
172 	version = le16_to_cpu(priv->usb_dev->descriptor.bcdDevice);
173 	dev_info(&interface->dev,
174 		 "version %x.%02x found at bus %03d address %03d",
175 		 version >> 8, version & 0xff,
176 		 priv->usb_dev->bus->busnum, priv->usb_dev->devnum);
177 
178 	return 0;
179 }
180 
181 static void osif_disconnect(struct usb_interface *interface)
182 {
183 	struct osif_priv *priv = usb_get_intfdata(interface);
184 
185 	i2c_del_adapter(&(priv->adapter));
186 	usb_set_intfdata(interface, NULL);
187 	usb_put_dev(priv->usb_dev);
188 }
189 
190 static struct usb_driver osif_driver = {
191 	.name		= "RobotFuzz Open Source InterFace, OSIF",
192 	.probe		= osif_probe,
193 	.disconnect	= osif_disconnect,
194 	.id_table	= osif_table,
195 };
196 
197 module_usb_driver(osif_driver);
198 
199 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
200 MODULE_AUTHOR("Barry Carter <barry.carter@robotfuzz.com>");
201 MODULE_DESCRIPTION("RobotFuzz OSIF driver");
202 MODULE_LICENSE("GPL v2");
203