1 /*
2 * I2C bridge driver for the Greybus "generic" I2C module.
3 *
4 * Copyright 2014 Google Inc.
5 * Copyright 2014 Linaro Ltd.
6 *
7 * Released under the GPLv2 only.
8 */
9
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/slab.h>
13 #include <linux/i2c.h>
14
15 #include "greybus.h"
16 #include "gbphy.h"
17
18 struct gb_i2c_device {
19 struct gb_connection *connection;
20 struct gbphy_device *gbphy_dev;
21
22 u32 functionality;
23
24 struct i2c_adapter adapter;
25 };
26
27 /*
28 * Map Greybus i2c functionality bits into Linux ones
29 */
gb_i2c_functionality_map(u32 gb_i2c_functionality)30 static u32 gb_i2c_functionality_map(u32 gb_i2c_functionality)
31 {
32 return gb_i2c_functionality; /* All bits the same for now */
33 }
34
gb_i2c_functionality_operation(struct gb_i2c_device * gb_i2c_dev)35 static int gb_i2c_functionality_operation(struct gb_i2c_device *gb_i2c_dev)
36 {
37 struct gb_i2c_functionality_response response;
38 u32 functionality;
39 int ret;
40
41 ret = gb_operation_sync(gb_i2c_dev->connection,
42 GB_I2C_TYPE_FUNCTIONALITY,
43 NULL, 0, &response, sizeof(response));
44 if (ret)
45 return ret;
46
47 functionality = le32_to_cpu(response.functionality);
48 gb_i2c_dev->functionality = gb_i2c_functionality_map(functionality);
49
50 return 0;
51 }
52
53 /*
54 * Map Linux i2c_msg flags into Greybus i2c transfer op flags.
55 */
gb_i2c_transfer_op_flags_map(u16 flags)56 static u16 gb_i2c_transfer_op_flags_map(u16 flags)
57 {
58 return flags; /* All flags the same for now */
59 }
60
61 static void
gb_i2c_fill_transfer_op(struct gb_i2c_transfer_op * op,struct i2c_msg * msg)62 gb_i2c_fill_transfer_op(struct gb_i2c_transfer_op *op, struct i2c_msg *msg)
63 {
64 u16 flags = gb_i2c_transfer_op_flags_map(msg->flags);
65
66 op->addr = cpu_to_le16(msg->addr);
67 op->flags = cpu_to_le16(flags);
68 op->size = cpu_to_le16(msg->len);
69 }
70
71 static struct gb_operation *
gb_i2c_operation_create(struct gb_connection * connection,struct i2c_msg * msgs,u32 msg_count)72 gb_i2c_operation_create(struct gb_connection *connection,
73 struct i2c_msg *msgs, u32 msg_count)
74 {
75 struct gb_i2c_device *gb_i2c_dev = gb_connection_get_data(connection);
76 struct gb_i2c_transfer_request *request;
77 struct gb_operation *operation;
78 struct gb_i2c_transfer_op *op;
79 struct i2c_msg *msg;
80 u32 data_out_size = 0;
81 u32 data_in_size = 0;
82 size_t request_size;
83 void *data;
84 u16 op_count;
85 u32 i;
86
87 if (msg_count > (u32)U16_MAX) {
88 dev_err(&gb_i2c_dev->gbphy_dev->dev, "msg_count (%u) too big\n",
89 msg_count);
90 return NULL;
91 }
92 op_count = (u16)msg_count;
93
94 /*
95 * In addition to space for all message descriptors we need
96 * to have enough to hold all outbound message data.
97 */
98 msg = msgs;
99 for (i = 0; i < msg_count; i++, msg++)
100 if (msg->flags & I2C_M_RD)
101 data_in_size += (u32)msg->len;
102 else
103 data_out_size += (u32)msg->len;
104
105 request_size = sizeof(*request);
106 request_size += msg_count * sizeof(*op);
107 request_size += data_out_size;
108
109 /* Response consists only of incoming data */
110 operation = gb_operation_create(connection, GB_I2C_TYPE_TRANSFER,
111 request_size, data_in_size, GFP_KERNEL);
112 if (!operation)
113 return NULL;
114
115 request = operation->request->payload;
116 request->op_count = cpu_to_le16(op_count);
117 /* Fill in the ops array */
118 op = &request->ops[0];
119 msg = msgs;
120 for (i = 0; i < msg_count; i++)
121 gb_i2c_fill_transfer_op(op++, msg++);
122
123 if (!data_out_size)
124 return operation;
125
126 /* Copy over the outgoing data; it starts after the last op */
127 data = op;
128 msg = msgs;
129 for (i = 0; i < msg_count; i++) {
130 if (!(msg->flags & I2C_M_RD)) {
131 memcpy(data, msg->buf, msg->len);
132 data += msg->len;
133 }
134 msg++;
135 }
136
137 return operation;
138 }
139
gb_i2c_decode_response(struct i2c_msg * msgs,u32 msg_count,struct gb_i2c_transfer_response * response)140 static void gb_i2c_decode_response(struct i2c_msg *msgs, u32 msg_count,
141 struct gb_i2c_transfer_response *response)
142 {
143 struct i2c_msg *msg = msgs;
144 u8 *data;
145 u32 i;
146
147 if (!response)
148 return;
149 data = response->data;
150 for (i = 0; i < msg_count; i++) {
151 if (msg->flags & I2C_M_RD) {
152 memcpy(msg->buf, data, msg->len);
153 data += msg->len;
154 }
155 msg++;
156 }
157 }
158
159 /*
160 * Some i2c transfer operations return results that are expected.
161 */
gb_i2c_expected_transfer_error(int errno)162 static bool gb_i2c_expected_transfer_error(int errno)
163 {
164 return errno == -EAGAIN || errno == -ENODEV;
165 }
166
gb_i2c_transfer_operation(struct gb_i2c_device * gb_i2c_dev,struct i2c_msg * msgs,u32 msg_count)167 static int gb_i2c_transfer_operation(struct gb_i2c_device *gb_i2c_dev,
168 struct i2c_msg *msgs, u32 msg_count)
169 {
170 struct gb_connection *connection = gb_i2c_dev->connection;
171 struct device *dev = &gb_i2c_dev->gbphy_dev->dev;
172 struct gb_operation *operation;
173 int ret;
174
175 operation = gb_i2c_operation_create(connection, msgs, msg_count);
176 if (!operation)
177 return -ENOMEM;
178
179 ret = gbphy_runtime_get_sync(gb_i2c_dev->gbphy_dev);
180 if (ret)
181 goto exit_operation_put;
182
183 ret = gb_operation_request_send_sync(operation);
184 if (!ret) {
185 struct gb_i2c_transfer_response *response;
186
187 response = operation->response->payload;
188 gb_i2c_decode_response(msgs, msg_count, response);
189 ret = msg_count;
190 } else if (!gb_i2c_expected_transfer_error(ret)) {
191 dev_err(dev, "transfer operation failed (%d)\n", ret);
192 }
193
194 gbphy_runtime_put_autosuspend(gb_i2c_dev->gbphy_dev);
195
196 exit_operation_put:
197 gb_operation_put(operation);
198
199 return ret;
200 }
201
gb_i2c_master_xfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int msg_count)202 static int gb_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
203 int msg_count)
204 {
205 struct gb_i2c_device *gb_i2c_dev;
206
207 gb_i2c_dev = i2c_get_adapdata(adap);
208
209 return gb_i2c_transfer_operation(gb_i2c_dev, msgs, msg_count);
210 }
211
212 #if 0
213 /* Later */
214 static int gb_i2c_smbus_xfer(struct i2c_adapter *adap,
215 u16 addr, unsigned short flags, char read_write,
216 u8 command, int size, union i2c_smbus_data *data)
217 {
218 struct gb_i2c_device *gb_i2c_dev;
219
220 gb_i2c_dev = i2c_get_adapdata(adap);
221
222 return 0;
223 }
224 #endif
225
gb_i2c_functionality(struct i2c_adapter * adap)226 static u32 gb_i2c_functionality(struct i2c_adapter *adap)
227 {
228 struct gb_i2c_device *gb_i2c_dev = i2c_get_adapdata(adap);
229
230 return gb_i2c_dev->functionality;
231 }
232
233 static const struct i2c_algorithm gb_i2c_algorithm = {
234 .master_xfer = gb_i2c_master_xfer,
235 /* .smbus_xfer = gb_i2c_smbus_xfer, */
236 .functionality = gb_i2c_functionality,
237 };
238
239 /*
240 * Do initial setup of the i2c device. This includes verifying we
241 * can support it (based on the protocol version it advertises).
242 * If that's OK, we get and cached its functionality bits.
243 *
244 * Note: gb_i2c_dev->connection is assumed to have been valid.
245 */
gb_i2c_device_setup(struct gb_i2c_device * gb_i2c_dev)246 static int gb_i2c_device_setup(struct gb_i2c_device *gb_i2c_dev)
247 {
248 /* Assume the functionality never changes, just get it once */
249 return gb_i2c_functionality_operation(gb_i2c_dev);
250 }
251
gb_i2c_probe(struct gbphy_device * gbphy_dev,const struct gbphy_device_id * id)252 static int gb_i2c_probe(struct gbphy_device *gbphy_dev,
253 const struct gbphy_device_id *id)
254 {
255 struct gb_connection *connection;
256 struct gb_i2c_device *gb_i2c_dev;
257 struct i2c_adapter *adapter;
258 int ret;
259
260 gb_i2c_dev = kzalloc(sizeof(*gb_i2c_dev), GFP_KERNEL);
261 if (!gb_i2c_dev)
262 return -ENOMEM;
263
264 connection = gb_connection_create(gbphy_dev->bundle,
265 le16_to_cpu(gbphy_dev->cport_desc->id),
266 NULL);
267 if (IS_ERR(connection)) {
268 ret = PTR_ERR(connection);
269 goto exit_i2cdev_free;
270 }
271
272 gb_i2c_dev->connection = connection;
273 gb_connection_set_data(connection, gb_i2c_dev);
274 gb_i2c_dev->gbphy_dev = gbphy_dev;
275 gb_gbphy_set_data(gbphy_dev, gb_i2c_dev);
276
277 ret = gb_connection_enable(connection);
278 if (ret)
279 goto exit_connection_destroy;
280
281 ret = gb_i2c_device_setup(gb_i2c_dev);
282 if (ret)
283 goto exit_connection_disable;
284
285 /* Looks good; up our i2c adapter */
286 adapter = &gb_i2c_dev->adapter;
287 adapter->owner = THIS_MODULE;
288 adapter->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
289 adapter->algo = &gb_i2c_algorithm;
290 /* adapter->algo_data = what? */
291
292 adapter->dev.parent = &gbphy_dev->dev;
293 snprintf(adapter->name, sizeof(adapter->name), "Greybus i2c adapter");
294 i2c_set_adapdata(adapter, gb_i2c_dev);
295
296 ret = i2c_add_adapter(adapter);
297 if (ret)
298 goto exit_connection_disable;
299
300 gbphy_runtime_put_autosuspend(gbphy_dev);
301 return 0;
302
303 exit_connection_disable:
304 gb_connection_disable(connection);
305 exit_connection_destroy:
306 gb_connection_destroy(connection);
307 exit_i2cdev_free:
308 kfree(gb_i2c_dev);
309
310 return ret;
311 }
312
gb_i2c_remove(struct gbphy_device * gbphy_dev)313 static void gb_i2c_remove(struct gbphy_device *gbphy_dev)
314 {
315 struct gb_i2c_device *gb_i2c_dev = gb_gbphy_get_data(gbphy_dev);
316 struct gb_connection *connection = gb_i2c_dev->connection;
317 int ret;
318
319 ret = gbphy_runtime_get_sync(gbphy_dev);
320 if (ret)
321 gbphy_runtime_get_noresume(gbphy_dev);
322
323 i2c_del_adapter(&gb_i2c_dev->adapter);
324 gb_connection_disable(connection);
325 gb_connection_destroy(connection);
326 kfree(gb_i2c_dev);
327 }
328
329 static const struct gbphy_device_id gb_i2c_id_table[] = {
330 { GBPHY_PROTOCOL(GREYBUS_PROTOCOL_I2C) },
331 { },
332 };
333 MODULE_DEVICE_TABLE(gbphy, gb_i2c_id_table);
334
335 static struct gbphy_driver i2c_driver = {
336 .name = "i2c",
337 .probe = gb_i2c_probe,
338 .remove = gb_i2c_remove,
339 .id_table = gb_i2c_id_table,
340 };
341
342 module_gbphy_driver(i2c_driver);
343 MODULE_LICENSE("GPL v2");
344