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_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
 123 static int cros_ec_probe_i2c(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
 153 static int cros_ec_remove_i2c(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
 163 static 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
 170 static 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
 178 static SIMPLE_DEV_PM_OPS(cros_ec_i2c_pm_ops, cros_ec_i2c_suspend,
 179                           cros_ec_i2c_resume);
 180
 181 static const struct i2c_device_id cros_ec_i2c_id[] = {
 182         { "cros-ec-i2c", 0 },
 183         { }
 184 };
 185 MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
 186
 187 static 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_probe_i2c,
 194         .remove         = cros_ec_remove_i2c,
 195         .id_table       = cros_ec_i2c_id,
 196 };
 197
 198 module_i2c_driver(cros_ec_driver);
 199
 200 MODULE_LICENSE("GPL");
 201 MODULE_DESCRIPTION("ChromeOS EC multi function device");