1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Driver for the TAOS evaluation modules
4 * These devices include an I2C controller which can be controlled over the
5 * serial port.
6 *
7 * Copyright (C) 2007 Jean Delvare <jdelvare@suse.de>
8 */
9
10 #include <linux/delay.h>
11 #include <linux/module.h>
12 #include <linux/slab.h>
13 #include <linux/interrupt.h>
14 #include <linux/input.h>
15 #include <linux/serio.h>
16 #include <linux/init.h>
17 #include <linux/i2c.h>
18
19 #define TAOS_BUFFER_SIZE 63
20
21 #define TAOS_STATE_INIT 0
22 #define TAOS_STATE_IDLE 1
23 #define TAOS_STATE_EOFF 2
24 #define TAOS_STATE_RECV 3
25
26 #define TAOS_CMD_RESET 0x12
27 #define TAOS_CMD_ECHO_ON '+'
28 #define TAOS_CMD_ECHO_OFF '-'
29
30 static DECLARE_WAIT_QUEUE_HEAD(wq);
31
32 struct taos_data {
33 struct i2c_adapter adapter;
34 struct i2c_client *client;
35 int state;
36 u8 addr; /* last used address */
37 unsigned char buffer[TAOS_BUFFER_SIZE];
38 unsigned int pos; /* position inside the buffer */
39 };
40
41 /* TAOS TSL2550 EVM */
42 static const struct i2c_board_info tsl2550_info = {
43 I2C_BOARD_INFO("tsl2550", 0x39),
44 };
45
46 /* Instantiate i2c devices based on the adapter name */
taos_instantiate_device(struct i2c_adapter * adapter)47 static struct i2c_client *taos_instantiate_device(struct i2c_adapter *adapter)
48 {
49 if (!strncmp(adapter->name, "TAOS TSL2550 EVM", 16)) {
50 dev_info(&adapter->dev, "Instantiating device %s at 0x%02x\n",
51 tsl2550_info.type, tsl2550_info.addr);
52 return i2c_new_client_device(adapter, &tsl2550_info);
53 }
54
55 return ERR_PTR(-ENODEV);
56 }
57
taos_smbus_xfer(struct i2c_adapter * adapter,u16 addr,unsigned short flags,char read_write,u8 command,int size,union i2c_smbus_data * data)58 static int taos_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
59 unsigned short flags, char read_write, u8 command,
60 int size, union i2c_smbus_data *data)
61 {
62 struct serio *serio = adapter->algo_data;
63 struct taos_data *taos = serio_get_drvdata(serio);
64 char *p;
65
66 /* Encode our transaction. "@" is for the device address, "$" for the
67 SMBus command and "#" for the data. */
68 p = taos->buffer;
69
70 /* The device remembers the last used address, no need to send it
71 again if it's the same */
72 if (addr != taos->addr)
73 p += sprintf(p, "@%02X", addr);
74
75 switch (size) {
76 case I2C_SMBUS_BYTE:
77 if (read_write == I2C_SMBUS_WRITE)
78 sprintf(p, "$#%02X", command);
79 else
80 sprintf(p, "$");
81 break;
82 case I2C_SMBUS_BYTE_DATA:
83 if (read_write == I2C_SMBUS_WRITE)
84 sprintf(p, "$%02X#%02X", command, data->byte);
85 else
86 sprintf(p, "$%02X", command);
87 break;
88 default:
89 dev_warn(&adapter->dev, "Unsupported transaction %d\n", size);
90 return -EOPNOTSUPP;
91 }
92
93 /* Send the transaction to the TAOS EVM */
94 dev_dbg(&adapter->dev, "Command buffer: %s\n", taos->buffer);
95 for (p = taos->buffer; *p; p++)
96 serio_write(serio, *p);
97
98 taos->addr = addr;
99
100 /* Start the transaction and read the answer */
101 taos->pos = 0;
102 taos->state = TAOS_STATE_RECV;
103 serio_write(serio, read_write == I2C_SMBUS_WRITE ? '>' : '<');
104 wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
105 msecs_to_jiffies(150));
106 if (taos->state != TAOS_STATE_IDLE
107 || taos->pos != 5) {
108 dev_err(&adapter->dev, "Transaction timeout (pos=%d)\n",
109 taos->pos);
110 return -EIO;
111 }
112 dev_dbg(&adapter->dev, "Answer buffer: %s\n", taos->buffer);
113
114 /* Interpret the returned string */
115 p = taos->buffer + 1;
116 p[3] = '\0';
117 if (!strcmp(p, "NAK"))
118 return -ENODEV;
119
120 if (read_write == I2C_SMBUS_WRITE) {
121 if (!strcmp(p, "ACK"))
122 return 0;
123 } else {
124 if (p[0] == 'x') {
125 /*
126 * Voluntarily dropping error code of kstrtou8 since all
127 * error code that it could return are invalid according
128 * to Documentation/i2c/fault-codes.rst.
129 */
130 if (kstrtou8(p + 1, 16, &data->byte))
131 return -EPROTO;
132 return 0;
133 }
134 }
135
136 return -EIO;
137 }
138
taos_smbus_func(struct i2c_adapter * adapter)139 static u32 taos_smbus_func(struct i2c_adapter *adapter)
140 {
141 return I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA;
142 }
143
144 static const struct i2c_algorithm taos_algorithm = {
145 .smbus_xfer = taos_smbus_xfer,
146 .functionality = taos_smbus_func,
147 };
148
taos_interrupt(struct serio * serio,unsigned char data,unsigned int flags)149 static irqreturn_t taos_interrupt(struct serio *serio, unsigned char data,
150 unsigned int flags)
151 {
152 struct taos_data *taos = serio_get_drvdata(serio);
153
154 switch (taos->state) {
155 case TAOS_STATE_INIT:
156 taos->buffer[taos->pos++] = data;
157 if (data == ':'
158 || taos->pos == TAOS_BUFFER_SIZE - 1) {
159 taos->buffer[taos->pos] = '\0';
160 taos->state = TAOS_STATE_IDLE;
161 wake_up_interruptible(&wq);
162 }
163 break;
164 case TAOS_STATE_EOFF:
165 taos->state = TAOS_STATE_IDLE;
166 wake_up_interruptible(&wq);
167 break;
168 case TAOS_STATE_RECV:
169 taos->buffer[taos->pos++] = data;
170 if (data == ']') {
171 taos->buffer[taos->pos] = '\0';
172 taos->state = TAOS_STATE_IDLE;
173 wake_up_interruptible(&wq);
174 }
175 break;
176 }
177
178 return IRQ_HANDLED;
179 }
180
181 /* Extract the adapter name from the buffer received after reset.
182 The buffer is modified and a pointer inside the buffer is returned. */
taos_adapter_name(char * buffer)183 static char *taos_adapter_name(char *buffer)
184 {
185 char *start, *end;
186
187 start = strstr(buffer, "TAOS ");
188 if (!start)
189 return NULL;
190
191 end = strchr(start, '\r');
192 if (!end)
193 return NULL;
194 *end = '\0';
195
196 return start;
197 }
198
taos_connect(struct serio * serio,struct serio_driver * drv)199 static int taos_connect(struct serio *serio, struct serio_driver *drv)
200 {
201 struct taos_data *taos;
202 struct i2c_adapter *adapter;
203 char *name;
204 int err;
205
206 taos = kzalloc(sizeof(struct taos_data), GFP_KERNEL);
207 if (!taos) {
208 err = -ENOMEM;
209 goto exit;
210 }
211 taos->state = TAOS_STATE_INIT;
212 serio_set_drvdata(serio, taos);
213
214 err = serio_open(serio, drv);
215 if (err)
216 goto exit_kfree;
217
218 adapter = &taos->adapter;
219 adapter->owner = THIS_MODULE;
220 adapter->algo = &taos_algorithm;
221 adapter->algo_data = serio;
222 adapter->dev.parent = &serio->dev;
223
224 /* Reset the TAOS evaluation module to identify it */
225 serio_write(serio, TAOS_CMD_RESET);
226 wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
227 msecs_to_jiffies(2000));
228
229 if (taos->state != TAOS_STATE_IDLE) {
230 err = -ENODEV;
231 dev_err(&serio->dev, "TAOS EVM reset failed (state=%d, "
232 "pos=%d)\n", taos->state, taos->pos);
233 goto exit_close;
234 }
235
236 name = taos_adapter_name(taos->buffer);
237 if (!name) {
238 err = -ENODEV;
239 dev_err(&serio->dev, "TAOS EVM identification failed\n");
240 goto exit_close;
241 }
242 strscpy(adapter->name, name, sizeof(adapter->name));
243
244 /* Turn echo off for better performance */
245 taos->state = TAOS_STATE_EOFF;
246 serio_write(serio, TAOS_CMD_ECHO_OFF);
247
248 wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
249 msecs_to_jiffies(250));
250 if (taos->state != TAOS_STATE_IDLE) {
251 err = -ENODEV;
252 dev_err(&serio->dev, "TAOS EVM echo off failed "
253 "(state=%d)\n", taos->state);
254 goto exit_close;
255 }
256
257 err = i2c_add_adapter(adapter);
258 if (err)
259 goto exit_close;
260 dev_info(&serio->dev, "Connected to TAOS EVM\n");
261
262 taos->client = taos_instantiate_device(adapter);
263 return 0;
264
265 exit_close:
266 serio_close(serio);
267 exit_kfree:
268 kfree(taos);
269 exit:
270 return err;
271 }
272
taos_disconnect(struct serio * serio)273 static void taos_disconnect(struct serio *serio)
274 {
275 struct taos_data *taos = serio_get_drvdata(serio);
276
277 i2c_unregister_device(taos->client);
278 i2c_del_adapter(&taos->adapter);
279 serio_close(serio);
280 kfree(taos);
281
282 dev_info(&serio->dev, "Disconnected from TAOS EVM\n");
283 }
284
285 static const struct serio_device_id taos_serio_ids[] = {
286 {
287 .type = SERIO_RS232,
288 .proto = SERIO_TAOSEVM,
289 .id = SERIO_ANY,
290 .extra = SERIO_ANY,
291 },
292 { 0 }
293 };
294 MODULE_DEVICE_TABLE(serio, taos_serio_ids);
295
296 static struct serio_driver taos_drv = {
297 .driver = {
298 .name = "taos-evm",
299 },
300 .description = "TAOS evaluation module driver",
301 .id_table = taos_serio_ids,
302 .connect = taos_connect,
303 .disconnect = taos_disconnect,
304 .interrupt = taos_interrupt,
305 };
306
307 module_serio_driver(taos_drv);
308
309 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
310 MODULE_DESCRIPTION("TAOS evaluation module driver");
311 MODULE_LICENSE("GPL");
312