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
17struct 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 */
29static 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 */
41static 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 */
62static u16 gb_i2c_transfer_op_flags_map(u16 flags)
63{
64	return flags;	/* All flags the same for now */
65}
66
67static void
68gb_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
77static struct gb_operation *
78gb_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
146static 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 */
168static bool gb_i2c_expected_transfer_error(int errno)
169{
170	return errno == -EAGAIN || errno == -ENODEV;
171}
172
173static 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
202exit_operation_put:
203	gb_operation_put(operation);
204
205	return ret;
206}
207
208static 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
218static 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
225static const struct i2c_algorithm gb_i2c_algorithm = {
226	.master_xfer	= gb_i2c_master_xfer,
227	.functionality	= gb_i2c_functionality,
228};
229
230static 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
281exit_connection_disable:
282	gb_connection_disable(connection);
283exit_connection_destroy:
284	gb_connection_destroy(connection);
285exit_i2cdev_free:
286	kfree(gb_i2c_dev);
287
288	return ret;
289}
290
291static 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
307static const struct gbphy_device_id gb_i2c_id_table[] = {
308	{ GBPHY_PROTOCOL(GREYBUS_PROTOCOL_I2C) },
309	{ },
310};
311MODULE_DEVICE_TABLE(gbphy, gb_i2c_id_table);
312
313static 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
320module_gbphy_driver(i2c_driver);
321MODULE_LICENSE("GPL v2");
322