1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Driver for RobotFuzz OSIF
4  *
5  * Copyright (c) 2013 Andrew Lunn <andrew@lunn.ch>
6  * Copyright (c) 2007 Barry Carter <Barry.Carter@robotfuzz.com>
7  *
8  * Based on the i2c-tiny-usb by
9  *
10  * Copyright (C) 2006 Til Harbaum (Till@Harbaum.org)
11  */
12 
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/errno.h>
16 #include <linux/i2c.h>
17 #include <linux/slab.h>
18 #include <linux/usb.h>
19 
20 #define OSIFI2C_READ		20
21 #define OSIFI2C_WRITE		21
22 #define OSIFI2C_STOP		22
23 #define OSIFI2C_STATUS		23
24 #define OSIFI2C_SET_BIT_RATE	24
25 
26 #define STATUS_ADDRESS_ACK	0
27 #define STATUS_ADDRESS_NAK	2
28 
29 struct osif_priv {
30 	struct usb_device *usb_dev;
31 	struct usb_interface *interface;
32 	struct i2c_adapter adapter;
33 	unsigned char status;
34 };
35 
36 static int osif_usb_read(struct i2c_adapter *adapter, int cmd,
37 			 int value, int index, void *data, int len)
38 {
39 	struct osif_priv *priv = adapter->algo_data;
40 
41 	return usb_control_msg(priv->usb_dev, usb_rcvctrlpipe(priv->usb_dev, 0),
42 			       cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
43 			       USB_DIR_IN, value, index, data, len, 2000);
44 }
45 
46 static int osif_usb_write(struct i2c_adapter *adapter, int cmd,
47 			  int value, int index, void *data, int len)
48 {
49 
50 	struct osif_priv *priv = adapter->algo_data;
51 
52 	return usb_control_msg(priv->usb_dev, usb_sndctrlpipe(priv->usb_dev, 0),
53 			       cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
54 			       value, index, data, len, 2000);
55 }
56 
57 static int osif_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
58 			 int num)
59 {
60 	struct osif_priv *priv = adapter->algo_data;
61 	struct i2c_msg *pmsg;
62 	int ret;
63 	int i;
64 
65 	for (i = 0; i < num; i++) {
66 		pmsg = &msgs[i];
67 
68 		if (pmsg->flags & I2C_M_RD) {
69 			ret = osif_usb_read(adapter, OSIFI2C_READ,
70 					    pmsg->flags, pmsg->addr,
71 					    pmsg->buf, pmsg->len);
72 			if (ret != pmsg->len) {
73 				dev_err(&adapter->dev, "failure reading data\n");
74 				return -EREMOTEIO;
75 			}
76 		} else {
77 			ret = osif_usb_write(adapter, OSIFI2C_WRITE,
78 					     pmsg->flags, pmsg->addr,
79 					     pmsg->buf, pmsg->len);
80 			if (ret != pmsg->len) {
81 				dev_err(&adapter->dev, "failure writing data\n");
82 				return -EREMOTEIO;
83 			}
84 		}
85 
86 		ret = osif_usb_read(adapter, OSIFI2C_STOP, 0, 0, NULL, 0);
87 		if (ret) {
88 			dev_err(&adapter->dev, "failure sending STOP\n");
89 			return -EREMOTEIO;
90 		}
91 
92 		/* read status */
93 		ret = osif_usb_read(adapter, OSIFI2C_STATUS, 0, 0,
94 				    &priv->status, 1);
95 		if (ret != 1) {
96 			dev_err(&adapter->dev, "failure reading status\n");
97 			return -EREMOTEIO;
98 		}
99 
100 		if (priv->status != STATUS_ADDRESS_ACK) {
101 			dev_dbg(&adapter->dev, "status = %d\n", priv->status);
102 			return -EREMOTEIO;
103 		}
104 	}
105 
106 	return i;
107 }
108 
109 static u32 osif_func(struct i2c_adapter *adapter)
110 {
111 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
112 }
113 
114 static const struct i2c_algorithm osif_algorithm = {
115 	.master_xfer	= osif_xfer,
116 	.functionality	= osif_func,
117 };
118 
119 #define USB_OSIF_VENDOR_ID	0x1964
120 #define USB_OSIF_PRODUCT_ID	0x0001
121 
122 static const struct usb_device_id osif_table[] = {
123 	{ USB_DEVICE(USB_OSIF_VENDOR_ID, USB_OSIF_PRODUCT_ID) },
124 	{ }
125 };
126 MODULE_DEVICE_TABLE(usb, osif_table);
127 
128 static int osif_probe(struct usb_interface *interface,
129 			     const struct usb_device_id *id)
130 {
131 	int ret;
132 	struct osif_priv *priv;
133 	u16 version;
134 
135 	priv = devm_kzalloc(&interface->dev, sizeof(*priv), GFP_KERNEL);
136 	if (!priv)
137 		return -ENOMEM;
138 
139 	priv->usb_dev = usb_get_dev(interface_to_usbdev(interface));
140 	priv->interface = interface;
141 
142 	usb_set_intfdata(interface, priv);
143 
144 	priv->adapter.owner = THIS_MODULE;
145 	priv->adapter.class = I2C_CLASS_HWMON;
146 	priv->adapter.algo = &osif_algorithm;
147 	priv->adapter.algo_data = priv;
148 	snprintf(priv->adapter.name, sizeof(priv->adapter.name),
149 		 "OSIF at bus %03d device %03d",
150 		 priv->usb_dev->bus->busnum, priv->usb_dev->devnum);
151 
152 	/*
153 	 * Set bus frequency. The frequency is:
154 	 * 120,000,000 / ( 16 + 2 * div * 4^prescale).
155 	 * Using dev = 52, prescale = 0 give 100KHz */
156 	ret = osif_usb_read(&priv->adapter, OSIFI2C_SET_BIT_RATE, 52, 0,
157 			    NULL, 0);
158 	if (ret) {
159 		dev_err(&interface->dev, "failure sending bit rate");
160 		usb_put_dev(priv->usb_dev);
161 		return ret;
162 	}
163 
164 	i2c_add_adapter(&(priv->adapter));
165 
166 	version = le16_to_cpu(priv->usb_dev->descriptor.bcdDevice);
167 	dev_info(&interface->dev,
168 		 "version %x.%02x found at bus %03d address %03d",
169 		 version >> 8, version & 0xff,
170 		 priv->usb_dev->bus->busnum, priv->usb_dev->devnum);
171 
172 	return 0;
173 }
174 
175 static void osif_disconnect(struct usb_interface *interface)
176 {
177 	struct osif_priv *priv = usb_get_intfdata(interface);
178 
179 	i2c_del_adapter(&(priv->adapter));
180 	usb_set_intfdata(interface, NULL);
181 	usb_put_dev(priv->usb_dev);
182 }
183 
184 static struct usb_driver osif_driver = {
185 	.name		= "RobotFuzz Open Source InterFace, OSIF",
186 	.probe		= osif_probe,
187 	.disconnect	= osif_disconnect,
188 	.id_table	= osif_table,
189 };
190 
191 module_usb_driver(osif_driver);
192 
193 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
194 MODULE_AUTHOR("Barry Carter <barry.carter@robotfuzz.com>");
195 MODULE_DESCRIPTION("RobotFuzz OSIF driver");
196 MODULE_LICENSE("GPL v2");
197