1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Driver for the TAOS evaluation modules |
4 | * These devices include an I2C master 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 */ |
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(adap: adapter, info: &tsl2550_info); |
53 | } |
54 | |
55 | return ERR_PTR(error: -ENODEV); |
56 | } |
57 | |
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, "$" for the |
67 | SMBus command and "#" for the data. */ |
68 | p = taos->buffer; |
69 | |
70 | /* The device remembers the last used address, no need to send it |
71 | again if it's the same */ |
72 | if (addr != taos->addr) |
73 | p += sprintf(buf: p, fmt: "@%02X" , addr); |
74 | |
75 | switch (size) { |
76 | case I2C_SMBUS_BYTE: |
77 | if (read_write == I2C_SMBUS_WRITE) |
78 | sprintf(buf: p, fmt: "$#%02X" , command); |
79 | else |
80 | sprintf(buf: p, fmt: "$" ); |
81 | break; |
82 | case I2C_SMBUS_BYTE_DATA: |
83 | if (read_write == I2C_SMBUS_WRITE) |
84 | sprintf(buf: p, fmt: "$%02X#%02X" , command, data->byte); |
85 | else |
86 | sprintf(buf: p, fmt: "$%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, data: *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, data: 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(s: p + 1, base: 16, res: &data->byte)) |
131 | return -EPROTO; |
132 | return 0; |
133 | } |
134 | } |
135 | |
136 | return -EIO; |
137 | } |
138 | |
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 | |
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. */ |
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 | |
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(size: 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, data: 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(buffer: 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(adap: 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(objp: taos); |
269 | exit: |
270 | return err; |
271 | } |
272 | |
273 | static void taos_disconnect(struct serio *serio) |
274 | { |
275 | struct taos_data *taos = serio_get_drvdata(serio); |
276 | |
277 | i2c_unregister_device(client: taos->client); |
278 | i2c_del_adapter(adap: &taos->adapter); |
279 | serio_close(serio); |
280 | kfree(objp: 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 | |