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 <khali@linux-fr.org>
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  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, write to the Free Software
19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20  */
21 
22 #include <linux/delay.h>
23 #include <linux/module.h>
24 #include <linux/slab.h>
25 #include <linux/interrupt.h>
26 #include <linux/input.h>
27 #include <linux/serio.h>
28 #include <linux/init.h>
29 #include <linux/i2c.h>
30 
31 #define TAOS_BUFFER_SIZE	63
32 
33 #define TAOS_STATE_INIT		0
34 #define TAOS_STATE_IDLE		1
35 #define TAOS_STATE_EOFF		2
36 #define TAOS_STATE_RECV		3
37 
38 #define TAOS_CMD_RESET		0x12
39 #define TAOS_CMD_ECHO_ON	'+'
40 #define TAOS_CMD_ECHO_OFF	'-'
41 
42 static DECLARE_WAIT_QUEUE_HEAD(wq);
43 
44 struct taos_data {
45 	struct i2c_adapter adapter;
46 	struct i2c_client *client;
47 	int state;
48 	u8 addr;		/* last used address */
49 	unsigned char buffer[TAOS_BUFFER_SIZE];
50 	unsigned int pos;	/* position inside the buffer */
51 };
52 
53 /* TAOS TSL2550 EVM */
54 static struct i2c_board_info tsl2550_info = {
55 	I2C_BOARD_INFO("tsl2550", 0x39),
56 };
57 
58 /* Instantiate i2c devices based on the adapter name */
59 static struct i2c_client *taos_instantiate_device(struct i2c_adapter *adapter)
60 {
61 	if (!strncmp(adapter->name, "TAOS TSL2550 EVM", 16)) {
62 		dev_info(&adapter->dev, "Instantiating device %s at 0x%02x\n",
63 			tsl2550_info.type, tsl2550_info.addr);
64 		return i2c_new_device(adapter, &tsl2550_info);
65 	}
66 
67 	return NULL;
68 }
69 
70 static int taos_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
71 			   unsigned short flags, char read_write, u8 command,
72 			   int size, union i2c_smbus_data *data)
73 {
74 	struct serio *serio = adapter->algo_data;
75 	struct taos_data *taos = serio_get_drvdata(serio);
76 	char *p;
77 
78 	/* Encode our transaction. "@" is for the device address, "$" for the
79 	   SMBus command and "#" for the data. */
80 	p = taos->buffer;
81 
82 	/* The device remembers the last used address, no need to send it
83 	   again if it's the same */
84 	if (addr != taos->addr)
85 		p += sprintf(p, "@%02X", addr);
86 
87 	switch (size) {
88 	case I2C_SMBUS_BYTE:
89 		if (read_write == I2C_SMBUS_WRITE)
90 			sprintf(p, "$#%02X", command);
91 		else
92 			sprintf(p, "$");
93 		break;
94 	case I2C_SMBUS_BYTE_DATA:
95 		if (read_write == I2C_SMBUS_WRITE)
96 			sprintf(p, "$%02X#%02X", command, data->byte);
97 		else
98 			sprintf(p, "$%02X", command);
99 		break;
100 	default:
101 		dev_warn(&adapter->dev, "Unsupported transaction %d\n", size);
102 		return -EOPNOTSUPP;
103 	}
104 
105 	/* Send the transaction to the TAOS EVM */
106 	dev_dbg(&adapter->dev, "Command buffer: %s\n", taos->buffer);
107 	for (p = taos->buffer; *p; p++)
108 		serio_write(serio, *p);
109 
110 	taos->addr = addr;
111 
112 	/* Start the transaction and read the answer */
113 	taos->pos = 0;
114 	taos->state = TAOS_STATE_RECV;
115 	serio_write(serio, read_write == I2C_SMBUS_WRITE ? '>' : '<');
116 	wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
117 					 msecs_to_jiffies(150));
118 	if (taos->state != TAOS_STATE_IDLE
119 	 || taos->pos != 5) {
120 		dev_err(&adapter->dev, "Transaction timeout (pos=%d)\n",
121 			taos->pos);
122 		return -EIO;
123 	}
124 	dev_dbg(&adapter->dev, "Answer buffer: %s\n", taos->buffer);
125 
126 	/* Interpret the returned string */
127 	p = taos->buffer + 1;
128 	p[3] = '\0';
129 	if (!strcmp(p, "NAK"))
130 		return -ENODEV;
131 
132 	if (read_write == I2C_SMBUS_WRITE) {
133 		if (!strcmp(p, "ACK"))
134 			return 0;
135 	} else {
136 		if (p[0] == 'x') {
137 			data->byte = simple_strtol(p + 1, NULL, 16);
138 			return 0;
139 		}
140 	}
141 
142 	return -EIO;
143 }
144 
145 static u32 taos_smbus_func(struct i2c_adapter *adapter)
146 {
147 	return I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA;
148 }
149 
150 static const struct i2c_algorithm taos_algorithm = {
151 	.smbus_xfer	= taos_smbus_xfer,
152 	.functionality	= taos_smbus_func,
153 };
154 
155 static irqreturn_t taos_interrupt(struct serio *serio, unsigned char data,
156 				  unsigned int flags)
157 {
158 	struct taos_data *taos = serio_get_drvdata(serio);
159 
160 	switch (taos->state) {
161 	case TAOS_STATE_INIT:
162 		taos->buffer[taos->pos++] = data;
163 		if (data == ':'
164 		 || taos->pos == TAOS_BUFFER_SIZE - 1) {
165 			taos->buffer[taos->pos] = '\0';
166 			taos->state = TAOS_STATE_IDLE;
167 			wake_up_interruptible(&wq);
168 		}
169 		break;
170 	case TAOS_STATE_EOFF:
171 		taos->state = TAOS_STATE_IDLE;
172 		wake_up_interruptible(&wq);
173 		break;
174 	case TAOS_STATE_RECV:
175 		taos->buffer[taos->pos++] = data;
176 		if (data == ']') {
177 			taos->buffer[taos->pos] = '\0';
178 			taos->state = TAOS_STATE_IDLE;
179 			wake_up_interruptible(&wq);
180 		}
181 		break;
182 	}
183 
184 	return IRQ_HANDLED;
185 }
186 
187 /* Extract the adapter name from the buffer received after reset.
188    The buffer is modified and a pointer inside the buffer is returned. */
189 static char *taos_adapter_name(char *buffer)
190 {
191 	char *start, *end;
192 
193 	start = strstr(buffer, "TAOS ");
194 	if (!start)
195 		return NULL;
196 
197 	end = strchr(start, '\r');
198 	if (!end)
199 		return NULL;
200 	*end = '\0';
201 
202 	return start;
203 }
204 
205 static int taos_connect(struct serio *serio, struct serio_driver *drv)
206 {
207 	struct taos_data *taos;
208 	struct i2c_adapter *adapter;
209 	char *name;
210 	int err;
211 
212 	taos = kzalloc(sizeof(struct taos_data), GFP_KERNEL);
213 	if (!taos) {
214 		err = -ENOMEM;
215 		goto exit;
216 	}
217 	taos->state = TAOS_STATE_INIT;
218 	serio_set_drvdata(serio, taos);
219 
220 	err = serio_open(serio, drv);
221 	if (err)
222 		goto exit_kfree;
223 
224 	adapter = &taos->adapter;
225 	adapter->owner = THIS_MODULE;
226 	adapter->algo = &taos_algorithm;
227 	adapter->algo_data = serio;
228 	adapter->dev.parent = &serio->dev;
229 
230 	/* Reset the TAOS evaluation module to identify it */
231 	serio_write(serio, TAOS_CMD_RESET);
232 	wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
233 					 msecs_to_jiffies(2000));
234 
235 	if (taos->state != TAOS_STATE_IDLE) {
236 		err = -ENODEV;
237 		dev_err(&serio->dev, "TAOS EVM reset failed (state=%d, "
238 			"pos=%d)\n", taos->state, taos->pos);
239 		goto exit_close;
240 	}
241 
242 	name = taos_adapter_name(taos->buffer);
243 	if (!name) {
244 		err = -ENODEV;
245 		dev_err(&serio->dev, "TAOS EVM identification failed\n");
246 		goto exit_close;
247 	}
248 	strlcpy(adapter->name, name, sizeof(adapter->name));
249 
250 	/* Turn echo off for better performance */
251 	taos->state = TAOS_STATE_EOFF;
252 	serio_write(serio, TAOS_CMD_ECHO_OFF);
253 
254 	wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
255 					 msecs_to_jiffies(250));
256 	if (taos->state != TAOS_STATE_IDLE) {
257 		err = -ENODEV;
258 		dev_err(&serio->dev, "TAOS EVM echo off failed "
259 			"(state=%d)\n", taos->state);
260 		goto exit_close;
261 	}
262 
263 	err = i2c_add_adapter(adapter);
264 	if (err)
265 		goto exit_close;
266 	dev_info(&serio->dev, "Connected to TAOS EVM\n");
267 
268 	taos->client = taos_instantiate_device(adapter);
269 	return 0;
270 
271  exit_close:
272 	serio_close(serio);
273  exit_kfree:
274 	kfree(taos);
275  exit:
276 	return err;
277 }
278 
279 static void taos_disconnect(struct serio *serio)
280 {
281 	struct taos_data *taos = serio_get_drvdata(serio);
282 
283 	if (taos->client)
284 		i2c_unregister_device(taos->client);
285 	i2c_del_adapter(&taos->adapter);
286 	serio_close(serio);
287 	kfree(taos);
288 
289 	dev_info(&serio->dev, "Disconnected from TAOS EVM\n");
290 }
291 
292 static struct serio_device_id taos_serio_ids[] = {
293 	{
294 		.type	= SERIO_RS232,
295 		.proto	= SERIO_TAOSEVM,
296 		.id	= SERIO_ANY,
297 		.extra	= SERIO_ANY,
298 	},
299 	{ 0 }
300 };
301 MODULE_DEVICE_TABLE(serio, taos_serio_ids);
302 
303 static struct serio_driver taos_drv = {
304 	.driver		= {
305 		.name	= "taos-evm",
306 	},
307 	.description	= "TAOS evaluation module driver",
308 	.id_table	= taos_serio_ids,
309 	.connect	= taos_connect,
310 	.disconnect	= taos_disconnect,
311 	.interrupt	= taos_interrupt,
312 };
313 
314 static int __init taos_init(void)
315 {
316 	return serio_register_driver(&taos_drv);
317 }
318 
319 static void __exit taos_exit(void)
320 {
321 	serio_unregister_driver(&taos_drv);
322 }
323 
324 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
325 MODULE_DESCRIPTION("TAOS evaluation module driver");
326 MODULE_LICENSE("GPL");
327 
328 module_init(taos_init);
329 module_exit(taos_exit);
330