1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * I2C bridge driver for the Greybus "generic" I2C module.
4  *
5  * Copyright 2014 Google Inc.
6  * Copyright 2014 Linaro Ltd.
7  */
8 
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/slab.h>
12 #include <linux/i2c.h>
13 #include <linux/greybus.h>
14 
15 #include "gbphy.h"
16 
17 struct gb_i2c_device {
18 	struct gb_connection	*connection;
19 	struct gbphy_device	*gbphy_dev;
20 
21 	u32			functionality;
22 
23 	struct i2c_adapter	adapter;
24 };
25 
26 /*
27  * Map Greybus i2c functionality bits into Linux ones
28  */
gb_i2c_functionality_map(u32 gb_i2c_functionality)29 static u32 gb_i2c_functionality_map(u32 gb_i2c_functionality)
30 {
31 	return gb_i2c_functionality;	/* All bits the same for now */
32 }
33 
34 /*
35  * Do initial setup of the i2c device.  This includes verifying we
36  * can support it (based on the protocol version it advertises).
37  * If that's OK, we get and cached its functionality bits.
38  *
39  * Note: gb_i2c_dev->connection is assumed to have been valid.
40  */
gb_i2c_device_setup(struct gb_i2c_device * gb_i2c_dev)41 static int gb_i2c_device_setup(struct gb_i2c_device *gb_i2c_dev)
42 {
43 	struct gb_i2c_functionality_response response;
44 	u32 functionality;
45 	int ret;
46 
47 	ret = gb_operation_sync(gb_i2c_dev->connection,
48 				GB_I2C_TYPE_FUNCTIONALITY,
49 				NULL, 0, &response, sizeof(response));
50 	if (ret)
51 		return ret;
52 
53 	functionality = le32_to_cpu(response.functionality);
54 	gb_i2c_dev->functionality = gb_i2c_functionality_map(functionality);
55 
56 	return 0;
57 }
58 
59 /*
60  * Map Linux i2c_msg flags into Greybus i2c transfer op flags.
61  */
gb_i2c_transfer_op_flags_map(u16 flags)62 static u16 gb_i2c_transfer_op_flags_map(u16 flags)
63 {
64 	return flags;	/* All flags the same for now */
65 }
66 
67 static void
gb_i2c_fill_transfer_op(struct gb_i2c_transfer_op * op,struct i2c_msg * msg)68 gb_i2c_fill_transfer_op(struct gb_i2c_transfer_op *op, struct i2c_msg *msg)
69 {
70 	u16 flags = gb_i2c_transfer_op_flags_map(msg->flags);
71 
72 	op->addr = cpu_to_le16(msg->addr);
73 	op->flags = cpu_to_le16(flags);
74 	op->size = cpu_to_le16(msg->len);
75 }
76 
77 static struct gb_operation *
gb_i2c_operation_create(struct gb_connection * connection,struct i2c_msg * msgs,u32 msg_count)78 gb_i2c_operation_create(struct gb_connection *connection,
79 			struct i2c_msg *msgs, u32 msg_count)
80 {
81 	struct gb_i2c_device *gb_i2c_dev = gb_connection_get_data(connection);
82 	struct gb_i2c_transfer_request *request;
83 	struct gb_operation *operation;
84 	struct gb_i2c_transfer_op *op;
85 	struct i2c_msg *msg;
86 	u32 data_out_size = 0;
87 	u32 data_in_size = 0;
88 	size_t request_size;
89 	void *data;
90 	u16 op_count;
91 	u32 i;
92 
93 	if (msg_count > (u32)U16_MAX) {
94 		dev_err(&gb_i2c_dev->gbphy_dev->dev, "msg_count (%u) too big\n",
95 			msg_count);
96 		return NULL;
97 	}
98 	op_count = (u16)msg_count;
99 
100 	/*
101 	 * In addition to space for all message descriptors we need
102 	 * to have enough to hold all outbound message data.
103 	 */
104 	msg = msgs;
105 	for (i = 0; i < msg_count; i++, msg++)
106 		if (msg->flags & I2C_M_RD)
107 			data_in_size += (u32)msg->len;
108 		else
109 			data_out_size += (u32)msg->len;
110 
111 	request_size = sizeof(*request);
112 	request_size += msg_count * sizeof(*op);
113 	request_size += data_out_size;
114 
115 	/* Response consists only of incoming data */
116 	operation = gb_operation_create(connection, GB_I2C_TYPE_TRANSFER,
117 					request_size, data_in_size, GFP_KERNEL);
118 	if (!operation)
119 		return NULL;
120 
121 	request = operation->request->payload;
122 	request->op_count = cpu_to_le16(op_count);
123 	/* Fill in the ops array */
124 	op = &request->ops[0];
125 	msg = msgs;
126 	for (i = 0; i < msg_count; i++)
127 		gb_i2c_fill_transfer_op(op++, msg++);
128 
129 	if (!data_out_size)
130 		return operation;
131 
132 	/* Copy over the outgoing data; it starts after the last op */
133 	data = op;
134 	msg = msgs;
135 	for (i = 0; i < msg_count; i++) {
136 		if (!(msg->flags & I2C_M_RD)) {
137 			memcpy(data, msg->buf, msg->len);
138 			data += msg->len;
139 		}
140 		msg++;
141 	}
142 
143 	return operation;
144 }
145 
gb_i2c_decode_response(struct i2c_msg * msgs,u32 msg_count,struct gb_i2c_transfer_response * response)146 static void gb_i2c_decode_response(struct i2c_msg *msgs, u32 msg_count,
147 				   struct gb_i2c_transfer_response *response)
148 {
149 	struct i2c_msg *msg = msgs;
150 	u8 *data;
151 	u32 i;
152 
153 	if (!response)
154 		return;
155 	data = response->data;
156 	for (i = 0; i < msg_count; i++) {
157 		if (msg->flags & I2C_M_RD) {
158 			memcpy(msg->buf, data, msg->len);
159 			data += msg->len;
160 		}
161 		msg++;
162 	}
163 }
164 
165 /*
166  * Some i2c transfer operations return results that are expected.
167  */
gb_i2c_expected_transfer_error(int errno)168 static bool gb_i2c_expected_transfer_error(int errno)
169 {
170 	return errno == -EAGAIN || errno == -ENODEV;
171 }
172 
gb_i2c_transfer_operation(struct gb_i2c_device * gb_i2c_dev,struct i2c_msg * msgs,u32 msg_count)173 static int gb_i2c_transfer_operation(struct gb_i2c_device *gb_i2c_dev,
174 				     struct i2c_msg *msgs, u32 msg_count)
175 {
176 	struct gb_connection *connection = gb_i2c_dev->connection;
177 	struct device *dev = &gb_i2c_dev->gbphy_dev->dev;
178 	struct gb_operation *operation;
179 	int ret;
180 
181 	operation = gb_i2c_operation_create(connection, msgs, msg_count);
182 	if (!operation)
183 		return -ENOMEM;
184 
185 	ret = gbphy_runtime_get_sync(gb_i2c_dev->gbphy_dev);
186 	if (ret)
187 		goto exit_operation_put;
188 
189 	ret = gb_operation_request_send_sync(operation);
190 	if (!ret) {
191 		struct gb_i2c_transfer_response *response;
192 
193 		response = operation->response->payload;
194 		gb_i2c_decode_response(msgs, msg_count, response);
195 		ret = msg_count;
196 	} else if (!gb_i2c_expected_transfer_error(ret)) {
197 		dev_err(dev, "transfer operation failed (%d)\n", ret);
198 	}
199 
200 	gbphy_runtime_put_autosuspend(gb_i2c_dev->gbphy_dev);
201 
202 exit_operation_put:
203 	gb_operation_put(operation);
204 
205 	return ret;
206 }
207 
gb_i2c_master_xfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int msg_count)208 static int gb_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
209 			      int msg_count)
210 {
211 	struct gb_i2c_device *gb_i2c_dev;
212 
213 	gb_i2c_dev = i2c_get_adapdata(adap);
214 
215 	return gb_i2c_transfer_operation(gb_i2c_dev, msgs, msg_count);
216 }
217 
gb_i2c_functionality(struct i2c_adapter * adap)218 static u32 gb_i2c_functionality(struct i2c_adapter *adap)
219 {
220 	struct gb_i2c_device *gb_i2c_dev = i2c_get_adapdata(adap);
221 
222 	return gb_i2c_dev->functionality;
223 }
224 
225 static const struct i2c_algorithm gb_i2c_algorithm = {
226 	.master_xfer	= gb_i2c_master_xfer,
227 	.functionality	= gb_i2c_functionality,
228 };
229 
gb_i2c_probe(struct gbphy_device * gbphy_dev,const struct gbphy_device_id * id)230 static int gb_i2c_probe(struct gbphy_device *gbphy_dev,
231 			const struct gbphy_device_id *id)
232 {
233 	struct gb_connection *connection;
234 	struct gb_i2c_device *gb_i2c_dev;
235 	struct i2c_adapter *adapter;
236 	int ret;
237 
238 	gb_i2c_dev = kzalloc(sizeof(*gb_i2c_dev), GFP_KERNEL);
239 	if (!gb_i2c_dev)
240 		return -ENOMEM;
241 
242 	connection =
243 		gb_connection_create(gbphy_dev->bundle,
244 				     le16_to_cpu(gbphy_dev->cport_desc->id),
245 				     NULL);
246 	if (IS_ERR(connection)) {
247 		ret = PTR_ERR(connection);
248 		goto exit_i2cdev_free;
249 	}
250 
251 	gb_i2c_dev->connection = connection;
252 	gb_connection_set_data(connection, gb_i2c_dev);
253 	gb_i2c_dev->gbphy_dev = gbphy_dev;
254 	gb_gbphy_set_data(gbphy_dev, gb_i2c_dev);
255 
256 	ret = gb_connection_enable(connection);
257 	if (ret)
258 		goto exit_connection_destroy;
259 
260 	ret = gb_i2c_device_setup(gb_i2c_dev);
261 	if (ret)
262 		goto exit_connection_disable;
263 
264 	/* Looks good; up our i2c adapter */
265 	adapter = &gb_i2c_dev->adapter;
266 	adapter->owner = THIS_MODULE;
267 	adapter->class = I2C_CLASS_HWMON;
268 	adapter->algo = &gb_i2c_algorithm;
269 
270 	adapter->dev.parent = &gbphy_dev->dev;
271 	snprintf(adapter->name, sizeof(adapter->name), "Greybus i2c adapter");
272 	i2c_set_adapdata(adapter, gb_i2c_dev);
273 
274 	ret = i2c_add_adapter(adapter);
275 	if (ret)
276 		goto exit_connection_disable;
277 
278 	gbphy_runtime_put_autosuspend(gbphy_dev);
279 	return 0;
280 
281 exit_connection_disable:
282 	gb_connection_disable(connection);
283 exit_connection_destroy:
284 	gb_connection_destroy(connection);
285 exit_i2cdev_free:
286 	kfree(gb_i2c_dev);
287 
288 	return ret;
289 }
290 
gb_i2c_remove(struct gbphy_device * gbphy_dev)291 static void gb_i2c_remove(struct gbphy_device *gbphy_dev)
292 {
293 	struct gb_i2c_device *gb_i2c_dev = gb_gbphy_get_data(gbphy_dev);
294 	struct gb_connection *connection = gb_i2c_dev->connection;
295 	int ret;
296 
297 	ret = gbphy_runtime_get_sync(gbphy_dev);
298 	if (ret)
299 		gbphy_runtime_get_noresume(gbphy_dev);
300 
301 	i2c_del_adapter(&gb_i2c_dev->adapter);
302 	gb_connection_disable(connection);
303 	gb_connection_destroy(connection);
304 	kfree(gb_i2c_dev);
305 }
306 
307 static const struct gbphy_device_id gb_i2c_id_table[] = {
308 	{ GBPHY_PROTOCOL(GREYBUS_PROTOCOL_I2C) },
309 	{ },
310 };
311 MODULE_DEVICE_TABLE(gbphy, gb_i2c_id_table);
312 
313 static struct gbphy_driver i2c_driver = {
314 	.name		= "i2c",
315 	.probe		= gb_i2c_probe,
316 	.remove		= gb_i2c_remove,
317 	.id_table	= gb_i2c_id_table,
318 };
319 
320 module_gbphy_driver(i2c_driver);
321 MODULE_DESCRIPTION("I2C bridge driver for the Greybus 'generic' I2C module");
322 MODULE_LICENSE("GPL v2");
323