linux/drivers/mfd/cros_ec_i2c.c
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   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_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
 153static 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
 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_probe_i2c,
 194        .remove         = cros_ec_remove_i2c,
 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");
 202
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