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authorSimon Glass <sjg@chromium.org>2013-02-25 14:08:38 -0800
committerSamuel Ortiz <sameo@linux.intel.com>2013-04-05 11:20:13 +0200
commit89969009485fa9e62814afaa438c12c45d7d2def (patch)
tree91fda02a31a094727ade6f8bb35aebdd392b9e61 /drivers/mfd/cros_ec_i2c.c
parent4ab6174e8cdb007cf500e484bdf454b8d14d524a (diff)
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>
Diffstat (limited to 'drivers/mfd/cros_ec_i2c.c')
-rw-r--r--drivers/mfd/cros_ec_i2c.c201
1 files changed, 201 insertions, 0 deletions
diff --git a/drivers/mfd/cros_ec_i2c.c b/drivers/mfd/cros_ec_i2c.c
new file mode 100644
index 000000000000..123044608b63
--- /dev/null
+++ b/drivers/mfd/cros_ec_i2c.c
@@ -0,0 +1,201 @@
+/*
+ * ChromeOS EC multi-function device (I2C)
+ *
+ * Copyright (C) 2012 Google, Inc
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/cros_ec.h>
+#include <linux/mfd/cros_ec_commands.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+static inline struct cros_ec_device *to_ec_dev(struct device *dev)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+
+ return i2c_get_clientdata(client);
+}
+
+static int cros_ec_command_xfer(struct cros_ec_device *ec_dev,
+ struct cros_ec_msg *msg)
+{
+ struct i2c_client *client = ec_dev->priv;
+ int ret = -ENOMEM;
+ int i;
+ int packet_len;
+ u8 *out_buf = NULL;
+ u8 *in_buf = NULL;
+ u8 sum;
+ struct i2c_msg i2c_msg[2];
+
+ i2c_msg[0].addr = client->addr;
+ i2c_msg[0].flags = 0;
+ i2c_msg[1].addr = client->addr;
+ i2c_msg[1].flags = I2C_M_RD;
+
+ /*
+ * allocate larger packet (one byte for checksum, one byte for
+ * length, and one for result code)
+ */
+ packet_len = msg->in_len + 3;
+ in_buf = kzalloc(packet_len, GFP_KERNEL);
+ if (!in_buf)
+ goto done;
+ i2c_msg[1].len = packet_len;
+ i2c_msg[1].buf = (char *)in_buf;
+
+ /*
+ * allocate larger packet (one byte for checksum, one for
+ * command code, one for length, and one for command version)
+ */
+ packet_len = msg->out_len + 4;
+ out_buf = kzalloc(packet_len, GFP_KERNEL);
+ if (!out_buf)
+ goto done;
+ i2c_msg[0].len = packet_len;
+ i2c_msg[0].buf = (char *)out_buf;
+
+ out_buf[0] = EC_CMD_VERSION0 + msg->version;
+ out_buf[1] = msg->cmd;
+ out_buf[2] = msg->out_len;
+
+ /* copy message payload and compute checksum */
+ sum = out_buf[0] + out_buf[1] + out_buf[2];
+ for (i = 0; i < msg->out_len; i++) {
+ out_buf[3 + i] = msg->out_buf[i];
+ sum += out_buf[3 + i];
+ }
+ out_buf[3 + msg->out_len] = sum;
+
+ /* send command to EC and read answer */
+ ret = i2c_transfer(client->adapter, i2c_msg, 2);
+ if (ret < 0) {
+ dev_err(ec_dev->dev, "i2c transfer failed: %d\n", ret);
+ goto done;
+ } else if (ret != 2) {
+ dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
+ ret = -EIO;
+ goto done;
+ }
+
+ /* check response error code */
+ if (i2c_msg[1].buf[0]) {
+ dev_warn(ec_dev->dev, "command 0x%02x returned an error %d\n",
+ msg->cmd, i2c_msg[1].buf[0]);
+ ret = -EINVAL;
+ goto done;
+ }
+
+ /* copy response packet payload and compute checksum */
+ sum = in_buf[0] + in_buf[1];
+ for (i = 0; i < msg->in_len; i++) {
+ msg->in_buf[i] = in_buf[2 + i];
+ sum += in_buf[2 + i];
+ }
+ dev_dbg(ec_dev->dev, "packet: %*ph, sum = %02x\n",
+ i2c_msg[1].len, in_buf, sum);
+ if (sum != in_buf[2 + msg->in_len]) {
+ dev_err(ec_dev->dev, "bad packet checksum\n");
+ ret = -EBADMSG;
+ goto done;
+ }
+
+ ret = 0;
+ done:
+ kfree(in_buf);
+ kfree(out_buf);
+ return ret;
+}
+
+static int cros_ec_probe_i2c(struct i2c_client *client,
+ const struct i2c_device_id *dev_id)
+{
+ struct device *dev = &client->dev;
+ struct cros_ec_device *ec_dev = NULL;
+ int err;
+
+ ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
+ if (!ec_dev)
+ return -ENOMEM;
+
+ i2c_set_clientdata(client, ec_dev);
+ ec_dev->name = "I2C";
+ ec_dev->dev = dev;
+ ec_dev->priv = client;
+ ec_dev->irq = client->irq;
+ ec_dev->command_xfer = cros_ec_command_xfer;
+ ec_dev->ec_name = client->name;
+ ec_dev->phys_name = client->adapter->name;
+ ec_dev->parent = &client->dev;
+
+ err = cros_ec_register(ec_dev);
+ if (err) {
+ dev_err(dev, "cannot register EC\n");
+ return err;
+ }
+
+ return 0;
+}
+
+static int cros_ec_remove_i2c(struct i2c_client *client)
+{
+ struct cros_ec_device *ec_dev = i2c_get_clientdata(client);
+
+ cros_ec_remove(ec_dev);
+
+ return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int cros_ec_i2c_suspend(struct device *dev)
+{
+ struct cros_ec_device *ec_dev = to_ec_dev(dev);
+
+ return cros_ec_suspend(ec_dev);
+}
+
+static int cros_ec_i2c_resume(struct device *dev)
+{
+ struct cros_ec_device *ec_dev = to_ec_dev(dev);
+
+ return cros_ec_resume(ec_dev);
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(cros_ec_i2c_pm_ops, cros_ec_i2c_suspend,
+ cros_ec_i2c_resume);
+
+static const struct i2c_device_id cros_ec_i2c_id[] = {
+ { "cros-ec-i2c", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
+
+static struct i2c_driver cros_ec_driver = {
+ .driver = {
+ .name = "cros-ec-i2c",
+ .owner = THIS_MODULE,
+ .pm = &cros_ec_i2c_pm_ops,
+ },
+ .probe = cros_ec_probe_i2c,
+ .remove = cros_ec_remove_i2c,
+ .id_table = cros_ec_i2c_id,
+};
+
+module_i2c_driver(cros_ec_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ChromeOS EC multi function device");