1/*
2 * ChromeOS EC multi-function device (I2C)
3 *
4 * Copyright (C) 2012 Google, Inc
5 *
6 * This software is licensed under the terms of the GNU General Public
7 * License version 2, as published by the Free Software Foundation, and
8 * may be copied, distributed, and modified under those terms.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 */
15
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/i2c.h>
19#include <linux/interrupt.h>
20#include <linux/mfd/cros_ec.h>
21#include <linux/mfd/cros_ec_commands.h>
22#include <linux/platform_device.h>
23#include <linux/slab.h>
24
25static inline struct cros_ec_device *to_ec_dev(struct device *dev)
26{
27	struct i2c_client *client = to_i2c_client(dev);
28
29	return i2c_get_clientdata(client);
30}
31
32static int cros_ec_cmd_xfer_i2c(struct cros_ec_device *ec_dev,
33				struct cros_ec_command *msg)
34{
35	struct i2c_client *client = ec_dev->priv;
36	int ret = -ENOMEM;
37	int i;
38	int len;
39	int packet_len;
40	u8 *out_buf = NULL;
41	u8 *in_buf = NULL;
42	u8 sum;
43	struct i2c_msg i2c_msg[2];
44
45	i2c_msg[0].addr = client->addr;
46	i2c_msg[0].flags = 0;
47	i2c_msg[1].addr = client->addr;
48	i2c_msg[1].flags = I2C_M_RD;
49
50	/*
51	 * allocate larger packet (one byte for checksum, one byte for
52	 * length, and one for result code)
53	 */
54	packet_len = msg->insize + 3;
55	in_buf = kzalloc(packet_len, GFP_KERNEL);
56	if (!in_buf)
57		goto done;
58	i2c_msg[1].len = packet_len;
59	i2c_msg[1].buf = (char *)in_buf;
60
61	/*
62	 * allocate larger packet (one byte for checksum, one for
63	 * command code, one for length, and one for command version)
64	 */
65	packet_len = msg->outsize + 4;
66	out_buf = kzalloc(packet_len, GFP_KERNEL);
67	if (!out_buf)
68		goto done;
69	i2c_msg[0].len = packet_len;
70	i2c_msg[0].buf = (char *)out_buf;
71
72	out_buf[0] = EC_CMD_VERSION0 + msg->version;
73	out_buf[1] = msg->command;
74	out_buf[2] = msg->outsize;
75
76	/* copy message payload and compute checksum */
77	sum = out_buf[0] + out_buf[1] + out_buf[2];
78	for (i = 0; i < msg->outsize; i++) {
79		out_buf[3 + i] = msg->outdata[i];
80		sum += out_buf[3 + i];
81	}
82	out_buf[3 + msg->outsize] = sum;
83
84	/* send command to EC and read answer */
85	ret = i2c_transfer(client->adapter, i2c_msg, 2);
86	if (ret < 0) {
87		dev_err(ec_dev->dev, "i2c transfer failed: %d\n", ret);
88		goto done;
89	} else if (ret != 2) {
90		dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
91		ret = -EIO;
92		goto done;
93	}
94
95	/* check response error code */
96	msg->result = i2c_msg[1].buf[0];
97	ret = cros_ec_check_result(ec_dev, msg);
98	if (ret)
99		goto done;
100
101	len = in_buf[1];
102	if (len > msg->insize) {
103		dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
104			len, msg->insize);
105		ret = -ENOSPC;
106		goto done;
107	}
108
109	/* copy response packet payload and compute checksum */
110	sum = in_buf[0] + in_buf[1];
111	for (i = 0; i < len; i++) {
112		msg->indata[i] = in_buf[2 + i];
113		sum += in_buf[2 + i];
114	}
115	dev_dbg(ec_dev->dev, "packet: %*ph, sum = %02x\n",
116		i2c_msg[1].len, in_buf, sum);
117	if (sum != in_buf[2 + len]) {
118		dev_err(ec_dev->dev, "bad packet checksum\n");
119		ret = -EBADMSG;
120		goto done;
121	}
122
123	ret = len;
124 done:
125	kfree(in_buf);
126	kfree(out_buf);
127	return ret;
128}
129
130static int cros_ec_i2c_probe(struct i2c_client *client,
131			     const struct i2c_device_id *dev_id)
132{
133	struct device *dev = &client->dev;
134	struct cros_ec_device *ec_dev = NULL;
135	int err;
136
137 	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
138	if (!ec_dev)
139		return -ENOMEM;
140
141	i2c_set_clientdata(client, ec_dev);
142	ec_dev->dev = dev;
143	ec_dev->priv = client;
144	ec_dev->irq = client->irq;
145	ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
146	ec_dev->ec_name = client->name;
147	ec_dev->phys_name = client->adapter->name;
148	ec_dev->parent = &client->dev;
149
150	err = cros_ec_register(ec_dev);
151	if (err) {
152		dev_err(dev, "cannot register EC\n");
153		return err;
154	}
155
156	return 0;
157}
158
159static int cros_ec_i2c_remove(struct i2c_client *client)
160{
161	struct cros_ec_device *ec_dev = i2c_get_clientdata(client);
162
163	cros_ec_remove(ec_dev);
164
165	return 0;
166}
167
168#ifdef CONFIG_PM_SLEEP
169static int cros_ec_i2c_suspend(struct device *dev)
170{
171	struct cros_ec_device *ec_dev = to_ec_dev(dev);
172
173	return cros_ec_suspend(ec_dev);
174}
175
176static int cros_ec_i2c_resume(struct device *dev)
177{
178	struct cros_ec_device *ec_dev = to_ec_dev(dev);
179
180	return cros_ec_resume(ec_dev);
181}
182#endif
183
184static SIMPLE_DEV_PM_OPS(cros_ec_i2c_pm_ops, cros_ec_i2c_suspend,
185			  cros_ec_i2c_resume);
186
187static const struct i2c_device_id cros_ec_i2c_id[] = {
188	{ "cros-ec-i2c", 0 },
189	{ }
190};
191MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
192
193static struct i2c_driver cros_ec_driver = {
194	.driver	= {
195		.name	= "cros-ec-i2c",
196		.owner	= THIS_MODULE,
197		.pm	= &cros_ec_i2c_pm_ops,
198	},
199	.probe		= cros_ec_i2c_probe,
200	.remove		= cros_ec_i2c_remove,
201	.id_table	= cros_ec_i2c_id,
202};
203
204module_i2c_driver(cros_ec_driver);
205
206MODULE_LICENSE("GPL");
207MODULE_DESCRIPTION("ChromeOS EC multi function device");
208