mfd: cros_ec: Move protocol helpers out of the MFD driver

The MFD driver should only have the logic to instantiate its child devices
and setup any shared resources that will be used by the subdevices drivers.

The cros_ec MFD is more complex than expected since it also has helpers to
communicate with the EC. So the driver will only get more bigger as other
protocols are supported in the future. So move the communication protocol
helpers to its own driver as drivers/platform/chrome/cros_ec_proto.c.

Suggested-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

1 files changed, 115 insertions, 0 deletions

diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
new file mode 100644
index 000000000000..58e98a24fd08
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -0,0 +1,115 @@
+/*
+ * ChromeOS EC communication protocol helper functions
+ *
+ * Copyright (C) 2015 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/mfd/cros_ec.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#define EC_COMMAND_RETRIES	50
+
+int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
+		       struct cros_ec_command *msg)
+{
+	uint8_t *out;
+	int csum, i;
+
+	BUG_ON(msg->outsize > EC_PROTO2_MAX_PARAM_SIZE);
+	out = ec_dev->dout;
+	out[0] = EC_CMD_VERSION0 + msg->version;
+	out[1] = msg->command;
+	out[2] = msg->outsize;
+	csum = out[0] + out[1] + out[2];
+	for (i = 0; i < msg->outsize; i++)
+		csum += out[EC_MSG_TX_HEADER_BYTES + i] = msg->data[i];
+	out[EC_MSG_TX_HEADER_BYTES + msg->outsize] = (uint8_t)(csum & 0xff);
+
+	return EC_MSG_TX_PROTO_BYTES + msg->outsize;
+}
+EXPORT_SYMBOL(cros_ec_prepare_tx);
+
+int cros_ec_check_result(struct cros_ec_device *ec_dev,
+			 struct cros_ec_command *msg)
+{
+	switch (msg->result) {
+	case EC_RES_SUCCESS:
+		return 0;
+	case EC_RES_IN_PROGRESS:
+		dev_dbg(ec_dev->dev, "command 0x%02x in progress\n",
+			msg->command);
+		return -EAGAIN;
+	default:
+		dev_dbg(ec_dev->dev, "command 0x%02x returned %d\n",
+			msg->command, msg->result);
+		return 0;
+	}
+}
+EXPORT_SYMBOL(cros_ec_check_result);
+
+int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
+		     struct cros_ec_command *msg)
+{
+	int ret;
+
+	mutex_lock(&ec_dev->lock);
+	ret = ec_dev->cmd_xfer(ec_dev, msg);
+	if (msg->result == EC_RES_IN_PROGRESS) {
+		int i;
+		struct cros_ec_command *status_msg;
+		struct ec_response_get_comms_status *status;
+
+		status_msg = kmalloc(sizeof(*status_msg) + sizeof(*status),
+				     GFP_KERNEL);
+		if (!status_msg) {
+			ret = -ENOMEM;
+			goto exit;
+		}
+
+		status_msg->version = 0;
+		status_msg->command = EC_CMD_GET_COMMS_STATUS;
+		status_msg->insize = sizeof(*status);
+		status_msg->outsize = 0;
+
+		/*
+		 * Query the EC's status until it's no longer busy or
+		 * we encounter an error.
+		 */
+		for (i = 0; i < EC_COMMAND_RETRIES; i++) {
+			usleep_range(10000, 11000);
+
+			ret = ec_dev->cmd_xfer(ec_dev, status_msg);
+			if (ret < 0)
+				break;
+
+			msg->result = status_msg->result;
+			if (status_msg->result != EC_RES_SUCCESS)
+				break;
+
+			status = (struct ec_response_get_comms_status *)
+				 status_msg->data;
+			if (!(status->flags & EC_COMMS_STATUS_PROCESSING))
+				break;
+		}
+
+		kfree(status_msg);
+	}
+exit:
+	mutex_unlock(&ec_dev->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(cros_ec_cmd_xfer);