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![Doug Anderson](/assets/img/avatar_default.png)
We know how many bytes the EC should be sending us (which is also the number of bytes transferred) and also how many bytes the EC actually wanted to send to us. When computing the checksum and copying back data let's make sure we take the lesser of the two of those. We'll also complain if the EC tried to send us too many bytes. The EC sending us too few bytes is legit for when we send the EC an invalid command. This is based on similar code in cros_ec_spi. Signed-off-by: Doug Anderson <dianders@chromium.org> Reviewed-by: Simon Glass <sjg@chromium.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
207 lines
4.9 KiB
C
207 lines
4.9 KiB
C
/*
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* ChromeOS EC multi-function device (I2C)
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*
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* Copyright (C) 2012 Google, Inc
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*
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* This software is licensed under the terms of the GNU General Public
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* License version 2, as published by the Free Software Foundation, and
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* may be copied, distributed, and modified under those terms.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/i2c.h>
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#include <linux/interrupt.h>
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#include <linux/mfd/cros_ec.h>
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#include <linux/mfd/cros_ec_commands.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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static inline struct cros_ec_device *to_ec_dev(struct device *dev)
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{
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struct i2c_client *client = to_i2c_client(dev);
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return i2c_get_clientdata(client);
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}
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static int cros_ec_cmd_xfer_i2c(struct cros_ec_device *ec_dev,
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struct cros_ec_command *msg)
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{
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struct i2c_client *client = ec_dev->priv;
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int ret = -ENOMEM;
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int i;
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int len;
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int packet_len;
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u8 *out_buf = NULL;
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u8 *in_buf = NULL;
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u8 sum;
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struct i2c_msg i2c_msg[2];
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i2c_msg[0].addr = client->addr;
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i2c_msg[0].flags = 0;
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i2c_msg[1].addr = client->addr;
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i2c_msg[1].flags = I2C_M_RD;
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/*
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* allocate larger packet (one byte for checksum, one byte for
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* length, and one for result code)
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*/
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packet_len = msg->insize + 3;
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in_buf = kzalloc(packet_len, GFP_KERNEL);
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if (!in_buf)
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goto done;
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i2c_msg[1].len = packet_len;
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i2c_msg[1].buf = (char *)in_buf;
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/*
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* allocate larger packet (one byte for checksum, one for
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* command code, one for length, and one for command version)
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*/
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packet_len = msg->outsize + 4;
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out_buf = kzalloc(packet_len, GFP_KERNEL);
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if (!out_buf)
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goto done;
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i2c_msg[0].len = packet_len;
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i2c_msg[0].buf = (char *)out_buf;
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out_buf[0] = EC_CMD_VERSION0 + msg->version;
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out_buf[1] = msg->command;
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out_buf[2] = msg->outsize;
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/* copy message payload and compute checksum */
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sum = out_buf[0] + out_buf[1] + out_buf[2];
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for (i = 0; i < msg->outsize; i++) {
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out_buf[3 + i] = msg->outdata[i];
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sum += out_buf[3 + i];
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}
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out_buf[3 + msg->outsize] = sum;
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/* send command to EC and read answer */
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ret = i2c_transfer(client->adapter, i2c_msg, 2);
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if (ret < 0) {
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dev_err(ec_dev->dev, "i2c transfer failed: %d\n", ret);
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goto done;
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} else if (ret != 2) {
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dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
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ret = -EIO;
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goto done;
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}
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/* check response error code */
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msg->result = i2c_msg[1].buf[0];
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ret = cros_ec_check_result(ec_dev, msg);
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if (ret)
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goto done;
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len = in_buf[1];
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if (len > msg->insize) {
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dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
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len, msg->insize);
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ret = -ENOSPC;
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goto done;
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}
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/* copy response packet payload and compute checksum */
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sum = in_buf[0] + in_buf[1];
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for (i = 0; i < len; i++) {
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msg->indata[i] = in_buf[2 + i];
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sum += in_buf[2 + i];
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}
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dev_dbg(ec_dev->dev, "packet: %*ph, sum = %02x\n",
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i2c_msg[1].len, in_buf, sum);
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if (sum != in_buf[2 + len]) {
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dev_err(ec_dev->dev, "bad packet checksum\n");
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ret = -EBADMSG;
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goto done;
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}
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ret = len;
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done:
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kfree(in_buf);
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kfree(out_buf);
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return ret;
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}
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static int cros_ec_i2c_probe(struct i2c_client *client,
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const struct i2c_device_id *dev_id)
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{
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struct device *dev = &client->dev;
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struct cros_ec_device *ec_dev = NULL;
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int err;
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ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
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if (!ec_dev)
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return -ENOMEM;
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i2c_set_clientdata(client, ec_dev);
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ec_dev->dev = dev;
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ec_dev->priv = client;
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ec_dev->irq = client->irq;
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ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
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ec_dev->ec_name = client->name;
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ec_dev->phys_name = client->adapter->name;
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ec_dev->parent = &client->dev;
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err = cros_ec_register(ec_dev);
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if (err) {
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dev_err(dev, "cannot register EC\n");
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return err;
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}
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return 0;
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}
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static int cros_ec_i2c_remove(struct i2c_client *client)
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{
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struct cros_ec_device *ec_dev = i2c_get_clientdata(client);
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cros_ec_remove(ec_dev);
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return 0;
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}
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#ifdef CONFIG_PM_SLEEP
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static int cros_ec_i2c_suspend(struct device *dev)
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{
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struct cros_ec_device *ec_dev = to_ec_dev(dev);
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return cros_ec_suspend(ec_dev);
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}
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static int cros_ec_i2c_resume(struct device *dev)
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{
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struct cros_ec_device *ec_dev = to_ec_dev(dev);
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return cros_ec_resume(ec_dev);
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}
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#endif
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static SIMPLE_DEV_PM_OPS(cros_ec_i2c_pm_ops, cros_ec_i2c_suspend,
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cros_ec_i2c_resume);
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static const struct i2c_device_id cros_ec_i2c_id[] = {
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{ "cros-ec-i2c", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
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static struct i2c_driver cros_ec_driver = {
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.driver = {
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.name = "cros-ec-i2c",
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.owner = THIS_MODULE,
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.pm = &cros_ec_i2c_pm_ops,
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},
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.probe = cros_ec_i2c_probe,
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.remove = cros_ec_i2c_remove,
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.id_table = cros_ec_i2c_id,
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};
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module_i2c_driver(cros_ec_driver);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("ChromeOS EC multi function device");
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