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
to_ec_dev(struct device * dev)25 static 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
cros_ec_cmd_xfer_i2c(struct cros_ec_device * ec_dev,struct cros_ec_command * msg)32 static 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
cros_ec_i2c_probe(struct i2c_client * client,const struct i2c_device_id * dev_id)130 static 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
cros_ec_i2c_remove(struct i2c_client * client)159 static 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
cros_ec_i2c_suspend(struct device * dev)169 static 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
cros_ec_i2c_resume(struct device * dev)176 static 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
184 static SIMPLE_DEV_PM_OPS(cros_ec_i2c_pm_ops, cros_ec_i2c_suspend,
185 cros_ec_i2c_resume);
186
187 static const struct i2c_device_id cros_ec_i2c_id[] = {
188 { "cros-ec-i2c", 0 },
189 { }
190 };
191 MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
192
193 static 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
204 module_i2c_driver(cros_ec_driver);
205
206 MODULE_LICENSE("GPL");
207 MODULE_DESCRIPTION("ChromeOS EC multi function device");
208