drivers/mfd/cros_ec_i2c.c

   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
  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
  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
 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
 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
 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
 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");