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_command_xfer(struct cros_ec_device *ec_dev,
 33				struct cros_ec_msg *msg)
 34{
 35	struct i2c_client *client = ec_dev->priv;
 36	int ret = -ENOMEM;
 37	int i;
 38	int packet_len;
 39	u8 *out_buf = NULL;
 40	u8 *in_buf = NULL;
 41	u8 sum;
 42	struct i2c_msg i2c_msg[2];
 43
 44	i2c_msg[0].addr = client->addr;
 45	i2c_msg[0].flags = 0;
 46	i2c_msg[1].addr = client->addr;
 47	i2c_msg[1].flags = I2C_M_RD;
 48
 49	/*
 50	 * allocate larger packet (one byte for checksum, one byte for
 51	 * length, and one for result code)
 52	 */
 53	packet_len = msg->in_len + 3;
 54	in_buf = kzalloc(packet_len, GFP_KERNEL);
 55	if (!in_buf)
 56		goto done;
 57	i2c_msg[1].len = packet_len;
 58	i2c_msg[1].buf = (char *)in_buf;
 59
 60	/*
 61	 * allocate larger packet (one byte for checksum, one for
 62	 * command code, one for length, and one for command version)
 63	 */
 64	packet_len = msg->out_len + 4;
 65	out_buf = kzalloc(packet_len, GFP_KERNEL);
 66	if (!out_buf)
 67		goto done;
 68	i2c_msg[0].len = packet_len;
 69	i2c_msg[0].buf = (char *)out_buf;
 70
 71	out_buf[0] = EC_CMD_VERSION0 + msg->version;
 72	out_buf[1] = msg->cmd;
 73	out_buf[2] = msg->out_len;
 74
 75	/* copy message payload and compute checksum */
 76	sum = out_buf[0] + out_buf[1] + out_buf[2];
 77	for (i = 0; i < msg->out_len; i++) {
 78		out_buf[3 + i] = msg->out_buf[i];
 79		sum += out_buf[3 + i];
 80	}
 81	out_buf[3 + msg->out_len] = sum;
 82
 83	/* send command to EC and read answer */
 84	ret = i2c_transfer(client->adapter, i2c_msg, 2);
 85	if (ret < 0) {
 86		dev_err(ec_dev->dev, "i2c transfer failed: %d\n", ret);
 87		goto done;
 88	} else if (ret != 2) {
 89		dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
 90		ret = -EIO;
 91		goto done;
 92	}
 93
 94	/* check response error code */
 95	if (i2c_msg[1].buf[0]) {
 96		dev_warn(ec_dev->dev, "command 0x%02x returned an error %d\n",
 97			 msg->cmd, i2c_msg[1].buf[0]);
 98		ret = -EINVAL;
 99		goto done;
100	}
101
102	/* copy response packet payload and compute checksum */
103	sum = in_buf[0] + in_buf[1];
104	for (i = 0; i < msg->in_len; i++) {
105		msg->in_buf[i] = in_buf[2 + i];
106		sum += in_buf[2 + i];
107	}
108	dev_dbg(ec_dev->dev, "packet: %*ph, sum = %02x\n",
109		i2c_msg[1].len, in_buf, sum);
110	if (sum != in_buf[2 + msg->in_len]) {
111		dev_err(ec_dev->dev, "bad packet checksum\n");
112		ret = -EBADMSG;
113		goto done;
114	}
115
116	ret = 0;
117 done:
118	kfree(in_buf);
119	kfree(out_buf);
120	return ret;
121}
122
123static int cros_ec_i2c_probe(struct i2c_client *client,
124			     const struct i2c_device_id *dev_id)
125{
126	struct device *dev = &client->dev;
127	struct cros_ec_device *ec_dev = NULL;
128	int err;
129
130 	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
131	if (!ec_dev)
132		return -ENOMEM;
133
134	i2c_set_clientdata(client, ec_dev);
135	ec_dev->name = "I2C";
136	ec_dev->dev = dev;
137	ec_dev->priv = client;
138	ec_dev->irq = client->irq;
139	ec_dev->command_xfer = cros_ec_command_xfer;
140	ec_dev->ec_name = client->name;
141	ec_dev->phys_name = client->adapter->name;
142	ec_dev->parent = &client->dev;
143
144	err = cros_ec_register(ec_dev);
145	if (err) {
146		dev_err(dev, "cannot register EC\n");
147		return err;
148	}
149
150	return 0;
151}
152
153static int cros_ec_i2c_remove(struct i2c_client *client)
154{
155	struct cros_ec_device *ec_dev = i2c_get_clientdata(client);
156
157	cros_ec_remove(ec_dev);
158
159	return 0;
160}
161
162#ifdef CONFIG_PM_SLEEP
163static int cros_ec_i2c_suspend(struct device *dev)
164{
165	struct cros_ec_device *ec_dev = to_ec_dev(dev);
166
167	return cros_ec_suspend(ec_dev);
168}
169
170static int cros_ec_i2c_resume(struct device *dev)
171{
172	struct cros_ec_device *ec_dev = to_ec_dev(dev);
173
174	return cros_ec_resume(ec_dev);
175}
176#endif
177
178static SIMPLE_DEV_PM_OPS(cros_ec_i2c_pm_ops, cros_ec_i2c_suspend,
179			  cros_ec_i2c_resume);
180
181static const struct i2c_device_id cros_ec_i2c_id[] = {
182	{ "cros-ec-i2c", 0 },
183	{ }
184};
185MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
186
187static struct i2c_driver cros_ec_driver = {
188	.driver	= {
189		.name	= "cros-ec-i2c",
190		.owner	= THIS_MODULE,
191		.pm	= &cros_ec_i2c_pm_ops,
192	},
193	.probe		= cros_ec_i2c_probe,
194	.remove		= cros_ec_i2c_remove,
195	.id_table	= cros_ec_i2c_id,
196};
197
198module_i2c_driver(cros_ec_driver);
199
200MODULE_LICENSE("GPL");
201MODULE_DESCRIPTION("ChromeOS EC multi function device");