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
38static DECLARE_WAIT_QUEUE_HEAD(wq);
39
40struct 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 */
50static struct i2c_board_info tsl2550_info = {
51	I2C_BOARD_INFO("tsl2550", 0x39),
52};
53
54/* Instantiate i2c devices based on the adapter name */
55static 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
66static 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			data->byte = simple_strtol(p + 1, NULL, 16);
134			return 0;
135		}
136	}
137
138	return -EIO;
139}
140
141static u32 taos_smbus_func(struct i2c_adapter *adapter)
142{
143	return I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA;
144}
145
146static const struct i2c_algorithm taos_algorithm = {
147	.smbus_xfer	= taos_smbus_xfer,
148	.functionality	= taos_smbus_func,
149};
150
151static irqreturn_t taos_interrupt(struct serio *serio, unsigned char data,
152				  unsigned int flags)
153{
154	struct taos_data *taos = serio_get_drvdata(serio);
155
156	switch (taos->state) {
157	case TAOS_STATE_INIT:
158		taos->buffer[taos->pos++] = data;
159		if (data == ':'
160		 || taos->pos == TAOS_BUFFER_SIZE - 1) {
161			taos->buffer[taos->pos] = '\0';
162			taos->state = TAOS_STATE_IDLE;
163			wake_up_interruptible(&wq);
164		}
165		break;
166	case TAOS_STATE_EOFF:
167		taos->state = TAOS_STATE_IDLE;
168		wake_up_interruptible(&wq);
169		break;
170	case TAOS_STATE_RECV:
171		taos->buffer[taos->pos++] = data;
172		if (data == ']') {
173			taos->buffer[taos->pos] = '\0';
174			taos->state = TAOS_STATE_IDLE;
175			wake_up_interruptible(&wq);
176		}
177		break;
178	}
179
180	return IRQ_HANDLED;
181}
182
183/* Extract the adapter name from the buffer received after reset.
184   The buffer is modified and a pointer inside the buffer is returned. */
185static char *taos_adapter_name(char *buffer)
186{
187	char *start, *end;
188
189	start = strstr(buffer, "TAOS ");
190	if (!start)
191		return NULL;
192
193	end = strchr(start, '\r');
194	if (!end)
195		return NULL;
196	*end = '\0';
197
198	return start;
199}
200
201static int taos_connect(struct serio *serio, struct serio_driver *drv)
202{
203	struct taos_data *taos;
204	struct i2c_adapter *adapter;
205	char *name;
206	int err;
207
208	taos = kzalloc(sizeof(struct taos_data), GFP_KERNEL);
209	if (!taos) {
210		err = -ENOMEM;
211		goto exit;
212	}
213	taos->state = TAOS_STATE_INIT;
214	serio_set_drvdata(serio, taos);
215
216	err = serio_open(serio, drv);
217	if (err)
218		goto exit_kfree;
219
220	adapter = &taos->adapter;
221	adapter->owner = THIS_MODULE;
222	adapter->algo = &taos_algorithm;
223	adapter->algo_data = serio;
224	adapter->dev.parent = &serio->dev;
225
226	/* Reset the TAOS evaluation module to identify it */
227	serio_write(serio, TAOS_CMD_RESET);
228	wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
229					 msecs_to_jiffies(2000));
230
231	if (taos->state != TAOS_STATE_IDLE) {
232		err = -ENODEV;
233		dev_err(&serio->dev, "TAOS EVM reset failed (state=%d, "
234			"pos=%d)\n", taos->state, taos->pos);
235		goto exit_close;
236	}
237
238	name = taos_adapter_name(taos->buffer);
239	if (!name) {
240		err = -ENODEV;
241		dev_err(&serio->dev, "TAOS EVM identification failed\n");
242		goto exit_close;
243	}
244	strlcpy(adapter->name, name, sizeof(adapter->name));
245
246	/* Turn echo off for better performance */
247	taos->state = TAOS_STATE_EOFF;
248	serio_write(serio, TAOS_CMD_ECHO_OFF);
249
250	wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
251					 msecs_to_jiffies(250));
252	if (taos->state != TAOS_STATE_IDLE) {
253		err = -ENODEV;
254		dev_err(&serio->dev, "TAOS EVM echo off failed "
255			"(state=%d)\n", taos->state);
256		goto exit_close;
257	}
258
259	err = i2c_add_adapter(adapter);
260	if (err)
261		goto exit_close;
262	dev_info(&serio->dev, "Connected to TAOS EVM\n");
263
264	taos->client = taos_instantiate_device(adapter);
265	return 0;
266
267 exit_close:
268	serio_close(serio);
269 exit_kfree:
270	kfree(taos);
271 exit:
272	return err;
273}
274
275static void taos_disconnect(struct serio *serio)
276{
277	struct taos_data *taos = serio_get_drvdata(serio);
278
279	if (taos->client)
280		i2c_unregister_device(taos->client);
281	i2c_del_adapter(&taos->adapter);
282	serio_close(serio);
283	kfree(taos);
284
285	dev_info(&serio->dev, "Disconnected from TAOS EVM\n");
286}
287
288static struct serio_device_id taos_serio_ids[] = {
289	{
290		.type	= SERIO_RS232,
291		.proto	= SERIO_TAOSEVM,
292		.id	= SERIO_ANY,
293		.extra	= SERIO_ANY,
294	},
295	{ 0 }
296};
297MODULE_DEVICE_TABLE(serio, taos_serio_ids);
298
299static struct serio_driver taos_drv = {
300	.driver		= {
301		.name	= "taos-evm",
302	},
303	.description	= "TAOS evaluation module driver",
304	.id_table	= taos_serio_ids,
305	.connect	= taos_connect,
306	.disconnect	= taos_disconnect,
307	.interrupt	= taos_interrupt,
308};
309
310module_serio_driver(taos_drv);
311
312MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
313MODULE_DESCRIPTION("TAOS evaluation module driver");
314MODULE_LICENSE("GPL");
315