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mfd: Add ChromeOS EC I2C driver
This uses an I2C bus to talk to the ChromeOS EC. The protocol is defined by the EC and is fairly simple, with a length byte, checksum, command byte and version byte (to permit easy creation of new commands). Signed-off-by: Simon Glass <sjg@chromium.org> Signed-off-by: Che-Liang Chiou <clchiou@chromium.org> Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
This commit is contained in:
Simon Glass
Samuel Ortiz
parent
4ab6174e8c
commit
8996900948
@ -29,6 +29,16 @@ config MFD_CROS_EC
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You also ned to enable the driver for the bus you are using. The
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protocol for talking to the EC is defined by the bus driver.
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config MFD_CROS_EC_I2C
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tristate "ChromeOS Embedded Controller (I2C)"
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depends on MFD_CROS_EC && I2C
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help
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If you say Y here, you get support for talking to the ChromeOS
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EC through an I2C bus. This uses a simple byte-level protocol with
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a checksum. Failing accesses will be retried three times to
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improve reliability.
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config MFD_88PM800
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tristate "Support Marvell 88PM800"
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depends on I2C=y && GENERIC_HARDIRQS
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@ -9,6 +9,7 @@ obj-$(CONFIG_MFD_88PM805) += 88pm805.o 88pm80x.o
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obj-$(CONFIG_MFD_SM501) += sm501.o
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obj-$(CONFIG_MFD_ASIC3) += asic3.o tmio_core.o
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obj-$(CONFIG_MFD_CROS_EC) += cros_ec.o
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obj-$(CONFIG_MFD_CROS_EC_I2C) += cros_ec_i2c.o
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rtsx_pci-objs := rtsx_pcr.o rts5209.o rts5229.o rtl8411.o rts5227.o
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obj-$(CONFIG_MFD_RTSX_PCI) += rtsx_pci.o
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201
drivers/mfd/cros_ec_i2c.c
Normal file
201
drivers/mfd/cros_ec_i2c.c
Normal file
@ -0,0 +1,201 @@
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/*
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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_command_xfer(struct cros_ec_device *ec_dev,
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struct cros_ec_msg *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 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->in_len + 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->out_len + 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->cmd;
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out_buf[2] = msg->out_len;
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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->out_len; i++) {
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out_buf[3 + i] = msg->out_buf[i];
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sum += out_buf[3 + i];
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}
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out_buf[3 + msg->out_len] = 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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if (i2c_msg[1].buf[0]) {
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dev_warn(ec_dev->dev, "command 0x%02x returned an error %d\n",
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msg->cmd, i2c_msg[1].buf[0]);
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ret = -EINVAL;
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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 < msg->in_len; i++) {
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msg->in_buf[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 + msg->in_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 = 0;
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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_probe_i2c(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->name = "I2C";
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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->command_xfer = cros_ec_command_xfer;
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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_remove_i2c(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_probe_i2c,
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.remove = cros_ec_remove_i2c,
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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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