1 /*
2 * Driver for the TAOS evaluation modules
3 * These devices include an I2C master which can be controlled over the
4 * serial port.
5 *
6 * Copyright (C) 2007 Jean Delvare <jdelvare@suse.de>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; version 2 of the License.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 */
17
18 #include <linux/delay.h>
19 #include <linux/module.h>
20 #include <linux/slab.h>
21 #include <linux/interrupt.h>
22 #include <linux/input.h>
23 #include <linux/serio.h>
24 #include <linux/init.h>
25 #include <linux/i2c.h>
26
27 #define TAOS_BUFFER_SIZE 63
28
29 #define TAOS_STATE_INIT 0
30 #define TAOS_STATE_IDLE 1
31 #define TAOS_STATE_EOFF 2
32 #define TAOS_STATE_RECV 3
33
34 #define TAOS_CMD_RESET 0x12
35 #define TAOS_CMD_ECHO_ON '+'
36 #define TAOS_CMD_ECHO_OFF '-'
37
38 static DECLARE_WAIT_QUEUE_HEAD(wq);
39
40 struct taos_data {
41 struct i2c_adapter adapter;
42 struct i2c_client *client;
43 int state;
44 u8 addr; /* last used address */
45 unsigned char buffer[TAOS_BUFFER_SIZE];
46 unsigned int pos; /* position inside the buffer */
47 };
48
49 /* TAOS TSL2550 EVM */
50 static struct i2c_board_info tsl2550_info = {
51 I2C_BOARD_INFO("tsl2550", 0x39),
52 };
53
54 /* Instantiate i2c devices based on the adapter name */
taos_instantiate_device(struct i2c_adapter * adapter)55 static struct i2c_client *taos_instantiate_device(struct i2c_adapter *adapter)
56 {
57 if (!strncmp(adapter->name, "TAOS TSL2550 EVM", 16)) {
58 dev_info(&adapter->dev, "Instantiating device %s at 0x%02x\n",
59 tsl2550_info.type, tsl2550_info.addr);
60 return i2c_new_device(adapter, &tsl2550_info);
61 }
62
63 return NULL;
64 }
65
taos_smbus_xfer(struct i2c_adapter * adapter,u16 addr,unsigned short flags,char read_write,u8 command,int size,union i2c_smbus_data * data)66 static int taos_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
67 unsigned short flags, char read_write, u8 command,
68 int size, union i2c_smbus_data *data)
69 {
70 struct serio *serio = adapter->algo_data;
71 struct taos_data *taos = serio_get_drvdata(serio);
72 char *p;
73
74 /* Encode our transaction. "@" is for the device address, "$" for the
75 SMBus command and "#" for the data. */
76 p = taos->buffer;
77
78 /* The device remembers the last used address, no need to send it
79 again if it's the same */
80 if (addr != taos->addr)
81 p += sprintf(p, "@%02X", addr);
82
83 switch (size) {
84 case I2C_SMBUS_BYTE:
85 if (read_write == I2C_SMBUS_WRITE)
86 sprintf(p, "$#%02X", command);
87 else
88 sprintf(p, "$");
89 break;
90 case I2C_SMBUS_BYTE_DATA:
91 if (read_write == I2C_SMBUS_WRITE)
92 sprintf(p, "$%02X#%02X", command, data->byte);
93 else
94 sprintf(p, "$%02X", command);
95 break;
96 default:
97 dev_warn(&adapter->dev, "Unsupported transaction %d\n", size);
98 return -EOPNOTSUPP;
99 }
100
101 /* Send the transaction to the TAOS EVM */
102 dev_dbg(&adapter->dev, "Command buffer: %s\n", taos->buffer);
103 for (p = taos->buffer; *p; p++)
104 serio_write(serio, *p);
105
106 taos->addr = addr;
107
108 /* Start the transaction and read the answer */
109 taos->pos = 0;
110 taos->state = TAOS_STATE_RECV;
111 serio_write(serio, read_write == I2C_SMBUS_WRITE ? '>' : '<');
112 wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
113 msecs_to_jiffies(150));
114 if (taos->state != TAOS_STATE_IDLE
115 || taos->pos != 5) {
116 dev_err(&adapter->dev, "Transaction timeout (pos=%d)\n",
117 taos->pos);
118 return -EIO;
119 }
120 dev_dbg(&adapter->dev, "Answer buffer: %s\n", taos->buffer);
121
122 /* Interpret the returned string */
123 p = taos->buffer + 1;
124 p[3] = '\0';
125 if (!strcmp(p, "NAK"))
126 return -ENODEV;
127
128 if (read_write == I2C_SMBUS_WRITE) {
129 if (!strcmp(p, "ACK"))
130 return 0;
131 } else {
132 if (p[0] == 'x') {
133 /*
134 * Voluntarily dropping error code of kstrtou8 since all
135 * error code that it could return are invalid according
136 * to Documentation/i2c/fault-codes.
137 */
138 if (kstrtou8(p + 1, 16, &data->byte))
139 return -EPROTO;
140 return 0;
141 }
142 }
143
144 return -EIO;
145 }
146
taos_smbus_func(struct i2c_adapter * adapter)147 static u32 taos_smbus_func(struct i2c_adapter *adapter)
148 {
149 return I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA;
150 }
151
152 static const struct i2c_algorithm taos_algorithm = {
153 .smbus_xfer = taos_smbus_xfer,
154 .functionality = taos_smbus_func,
155 };
156
taos_interrupt(struct serio * serio,unsigned char data,unsigned int flags)157 static irqreturn_t taos_interrupt(struct serio *serio, unsigned char data,
158 unsigned int flags)
159 {
160 struct taos_data *taos = serio_get_drvdata(serio);
161
162 switch (taos->state) {
163 case TAOS_STATE_INIT:
164 taos->buffer[taos->pos++] = data;
165 if (data == ':'
166 || taos->pos == TAOS_BUFFER_SIZE - 1) {
167 taos->buffer[taos->pos] = '\0';
168 taos->state = TAOS_STATE_IDLE;
169 wake_up_interruptible(&wq);
170 }
171 break;
172 case TAOS_STATE_EOFF:
173 taos->state = TAOS_STATE_IDLE;
174 wake_up_interruptible(&wq);
175 break;
176 case TAOS_STATE_RECV:
177 taos->buffer[taos->pos++] = data;
178 if (data == ']') {
179 taos->buffer[taos->pos] = '\0';
180 taos->state = TAOS_STATE_IDLE;
181 wake_up_interruptible(&wq);
182 }
183 break;
184 }
185
186 return IRQ_HANDLED;
187 }
188
189 /* Extract the adapter name from the buffer received after reset.
190 The buffer is modified and a pointer inside the buffer is returned. */
taos_adapter_name(char * buffer)191 static char *taos_adapter_name(char *buffer)
192 {
193 char *start, *end;
194
195 start = strstr(buffer, "TAOS ");
196 if (!start)
197 return NULL;
198
199 end = strchr(start, '\r');
200 if (!end)
201 return NULL;
202 *end = '\0';
203
204 return start;
205 }
206
taos_connect(struct serio * serio,struct serio_driver * drv)207 static int taos_connect(struct serio *serio, struct serio_driver *drv)
208 {
209 struct taos_data *taos;
210 struct i2c_adapter *adapter;
211 char *name;
212 int err;
213
214 taos = kzalloc(sizeof(struct taos_data), GFP_KERNEL);
215 if (!taos) {
216 err = -ENOMEM;
217 goto exit;
218 }
219 taos->state = TAOS_STATE_INIT;
220 serio_set_drvdata(serio, taos);
221
222 err = serio_open(serio, drv);
223 if (err)
224 goto exit_kfree;
225
226 adapter = &taos->adapter;
227 adapter->owner = THIS_MODULE;
228 adapter->algo = &taos_algorithm;
229 adapter->algo_data = serio;
230 adapter->dev.parent = &serio->dev;
231
232 /* Reset the TAOS evaluation module to identify it */
233 serio_write(serio, TAOS_CMD_RESET);
234 wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
235 msecs_to_jiffies(2000));
236
237 if (taos->state != TAOS_STATE_IDLE) {
238 err = -ENODEV;
239 dev_err(&serio->dev, "TAOS EVM reset failed (state=%d, "
240 "pos=%d)\n", taos->state, taos->pos);
241 goto exit_close;
242 }
243
244 name = taos_adapter_name(taos->buffer);
245 if (!name) {
246 err = -ENODEV;
247 dev_err(&serio->dev, "TAOS EVM identification failed\n");
248 goto exit_close;
249 }
250 strlcpy(adapter->name, name, sizeof(adapter->name));
251
252 /* Turn echo off for better performance */
253 taos->state = TAOS_STATE_EOFF;
254 serio_write(serio, TAOS_CMD_ECHO_OFF);
255
256 wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
257 msecs_to_jiffies(250));
258 if (taos->state != TAOS_STATE_IDLE) {
259 err = -ENODEV;
260 dev_err(&serio->dev, "TAOS EVM echo off failed "
261 "(state=%d)\n", taos->state);
262 goto exit_close;
263 }
264
265 err = i2c_add_adapter(adapter);
266 if (err)
267 goto exit_close;
268 dev_info(&serio->dev, "Connected to TAOS EVM\n");
269
270 taos->client = taos_instantiate_device(adapter);
271 return 0;
272
273 exit_close:
274 serio_close(serio);
275 exit_kfree:
276 kfree(taos);
277 exit:
278 return err;
279 }
280
taos_disconnect(struct serio * serio)281 static void taos_disconnect(struct serio *serio)
282 {
283 struct taos_data *taos = serio_get_drvdata(serio);
284
285 i2c_unregister_device(taos->client);
286 i2c_del_adapter(&taos->adapter);
287 serio_close(serio);
288 kfree(taos);
289
290 dev_info(&serio->dev, "Disconnected from TAOS EVM\n");
291 }
292
293 static const struct serio_device_id taos_serio_ids[] = {
294 {
295 .type = SERIO_RS232,
296 .proto = SERIO_TAOSEVM,
297 .id = SERIO_ANY,
298 .extra = SERIO_ANY,
299 },
300 { 0 }
301 };
302 MODULE_DEVICE_TABLE(serio, taos_serio_ids);
303
304 static struct serio_driver taos_drv = {
305 .driver = {
306 .name = "taos-evm",
307 },
308 .description = "TAOS evaluation module driver",
309 .id_table = taos_serio_ids,
310 .connect = taos_connect,
311 .disconnect = taos_disconnect,
312 .interrupt = taos_interrupt,
313 };
314
315 module_serio_driver(taos_drv);
316
317 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
318 MODULE_DESCRIPTION("TAOS evaluation module driver");
319 MODULE_LICENSE("GPL");
320
