Date:   Fri, 16 Sep 2016 16:20:33 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org
Cc:     Johan Hovold <johan@...oldconsulting.com>,
        Rui Miguel Silva <rmfrfs@...il.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Sandeep Patil <sspatil@...gle.com>,
        Matt Porter <mporter@...nel.crashing.org>,
        John Stultz <john.stultz@...aro.org>,
        Rob Herring <robh@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Alex Elder <elder@...aro.org>, David Lin <dtwlin@...gle.com>,
        Bryan O'Donoghue <pure.logic@...us-software.ie>,
        Vaibhav Agarwal <vaibhav.agarwal@...aro.org>,
        Mark Greer <mgreer@...malcreek.com>
Subject: [patch 24/32] greybus: bridged phy i2c driver

This driver implements the Greybus bridged phy i2c class protocol.

Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/greybus/i2c.c |  343 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 343 insertions(+)

--- /dev/null
+++ b/drivers/greybus/i2c.c
@@ -0,0 +1,343 @@
+/*
+ * I2C bridge driver for the Greybus "generic" I2C module.
+ *
+ * Copyright 2014 Google Inc.
+ * Copyright 2014 Linaro Ltd.
+ *
+ * Released under the GPLv2 only.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+
+#include "greybus.h"
+#include "gbphy.h"
+
+struct gb_i2c_device {
+	struct gb_connection	*connection;
+	struct gbphy_device	*gbphy_dev;
+
+	u32			functionality;
+
+	struct i2c_adapter	adapter;
+};
+
+/*
+ * Map Greybus i2c functionality bits into Linux ones
+ */
+static u32 gb_i2c_functionality_map(u32 gb_i2c_functionality)
+{
+	return gb_i2c_functionality;	/* All bits the same for now */
+}
+
+static int gb_i2c_functionality_operation(struct gb_i2c_device *gb_i2c_dev)
+{
+	struct gb_i2c_functionality_response response;
+	u32 functionality;
+	int ret;
+
+	ret = gb_operation_sync(gb_i2c_dev->connection,
+				GB_I2C_TYPE_FUNCTIONALITY,
+				NULL, 0, &response, sizeof(response));
+	if (ret)
+		return ret;
+
+	functionality = le32_to_cpu(response.functionality);
+	gb_i2c_dev->functionality = gb_i2c_functionality_map(functionality);
+
+	return 0;
+}
+
+/*
+ * Map Linux i2c_msg flags into Greybus i2c transfer op flags.
+ */
+static u16 gb_i2c_transfer_op_flags_map(u16 flags)
+{
+	return flags;	/* All flags the same for now */
+}
+
+static void
+gb_i2c_fill_transfer_op(struct gb_i2c_transfer_op *op, struct i2c_msg *msg)
+{
+	u16 flags = gb_i2c_transfer_op_flags_map(msg->flags);
+
+	op->addr = cpu_to_le16(msg->addr);
+	op->flags = cpu_to_le16(flags);
+	op->size = cpu_to_le16(msg->len);
+}
+
+static struct gb_operation *
+gb_i2c_operation_create(struct gb_connection *connection,
+			struct i2c_msg *msgs, u32 msg_count)
+{
+	struct gb_i2c_device *gb_i2c_dev = gb_connection_get_data(connection);
+	struct gb_i2c_transfer_request *request;
+	struct gb_operation *operation;
+	struct gb_i2c_transfer_op *op;
+	struct i2c_msg *msg;
+	u32 data_out_size = 0;
+	u32 data_in_size = 0;
+	size_t request_size;
+	void *data;
+	u16 op_count;
+	u32 i;
+
+	if (msg_count > (u32)U16_MAX) {
+		dev_err(&gb_i2c_dev->gbphy_dev->dev, "msg_count (%u) too big\n",
+			msg_count);
+		return NULL;
+	}
+	op_count = (u16)msg_count;
+
+	/*
+	 * In addition to space for all message descriptors we need
+	 * to have enough to hold all outbound message data.
+	 */
+	msg = msgs;
+	for (i = 0; i < msg_count; i++, msg++)
+		if (msg->flags & I2C_M_RD)
+			data_in_size += (u32)msg->len;
+		else
+			data_out_size += (u32)msg->len;
+
+	request_size = sizeof(*request);
+	request_size += msg_count * sizeof(*op);
+	request_size += data_out_size;
+
+	/* Response consists only of incoming data */
+	operation = gb_operation_create(connection, GB_I2C_TYPE_TRANSFER,
+				request_size, data_in_size, GFP_KERNEL);
+	if (!operation)
+		return NULL;
+
+	request = operation->request->payload;
+	request->op_count = cpu_to_le16(op_count);
+	/* Fill in the ops array */
+	op = &request->ops[0];
+	msg = msgs;
+	for (i = 0; i < msg_count; i++)
+		gb_i2c_fill_transfer_op(op++, msg++);
+
+	if (!data_out_size)
+		return operation;
+
+	/* Copy over the outgoing data; it starts after the last op */
+	data = op;
+	msg = msgs;
+	for (i = 0; i < msg_count; i++) {
+		if (!(msg->flags & I2C_M_RD)) {
+			memcpy(data, msg->buf, msg->len);
+			data += msg->len;
+		}
+		msg++;
+	}
+
+	return operation;
+}
+
+static void gb_i2c_decode_response(struct i2c_msg *msgs, u32 msg_count,
+				struct gb_i2c_transfer_response *response)
+{
+	struct i2c_msg *msg = msgs;
+	u8 *data;
+	u32 i;
+
+	if (!response)
+		return;
+	data = response->data;
+	for (i = 0; i < msg_count; i++) {
+		if (msg->flags & I2C_M_RD) {
+			memcpy(msg->buf, data, msg->len);
+			data += msg->len;
+		}
+		msg++;
+	}
+}
+
+/*
+ * Some i2c transfer operations return results that are expected.
+ */
+static bool gb_i2c_expected_transfer_error(int errno)
+{
+	return errno == -EAGAIN || errno == -ENODEV;
+}
+
+static int gb_i2c_transfer_operation(struct gb_i2c_device *gb_i2c_dev,
+					struct i2c_msg *msgs, u32 msg_count)
+{
+	struct gb_connection *connection = gb_i2c_dev->connection;
+	struct device *dev = &gb_i2c_dev->gbphy_dev->dev;
+	struct gb_operation *operation;
+	int ret;
+
+	operation = gb_i2c_operation_create(connection, msgs, msg_count);
+	if (!operation)
+		return -ENOMEM;
+
+	ret = gbphy_runtime_get_sync(gb_i2c_dev->gbphy_dev);
+	if (ret)
+		goto exit_operation_put;
+
+	ret = gb_operation_request_send_sync(operation);
+	if (!ret) {
+		struct gb_i2c_transfer_response *response;
+
+		response = operation->response->payload;
+		gb_i2c_decode_response(msgs, msg_count, response);
+		ret = msg_count;
+	} else if (!gb_i2c_expected_transfer_error(ret)) {
+		dev_err(dev, "transfer operation failed (%d)\n", ret);
+	}
+
+	gbphy_runtime_put_autosuspend(gb_i2c_dev->gbphy_dev);
+
+exit_operation_put:
+	gb_operation_put(operation);
+
+	return ret;
+}
+
+static int gb_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+		int msg_count)
+{
+	struct gb_i2c_device *gb_i2c_dev;
+
+	gb_i2c_dev = i2c_get_adapdata(adap);
+
+	return gb_i2c_transfer_operation(gb_i2c_dev, msgs, msg_count);
+}
+
+#if 0
+/* Later */
+static int gb_i2c_smbus_xfer(struct i2c_adapter *adap,
+			u16 addr, unsigned short flags, char read_write,
+			u8 command, int size, union i2c_smbus_data *data)
+{
+	struct gb_i2c_device *gb_i2c_dev;
+
+	gb_i2c_dev = i2c_get_adapdata(adap);
+
+	return 0;
+}
+#endif
+
+static u32 gb_i2c_functionality(struct i2c_adapter *adap)
+{
+	struct gb_i2c_device *gb_i2c_dev = i2c_get_adapdata(adap);
+
+	return gb_i2c_dev->functionality;
+}
+
+static const struct i2c_algorithm gb_i2c_algorithm = {
+	.master_xfer	= gb_i2c_master_xfer,
+	/* .smbus_xfer	= gb_i2c_smbus_xfer, */
+	.functionality	= gb_i2c_functionality,
+};
+
+/*
+ * Do initial setup of the i2c device.  This includes verifying we
+ * can support it (based on the protocol version it advertises).
+ * If that's OK, we get and cached its functionality bits.
+ *
+ * Note: gb_i2c_dev->connection is assumed to have been valid.
+ */
+static int gb_i2c_device_setup(struct gb_i2c_device *gb_i2c_dev)
+{
+	/* Assume the functionality never changes, just get it once */
+	return gb_i2c_functionality_operation(gb_i2c_dev);
+}
+
+static int gb_i2c_probe(struct gbphy_device *gbphy_dev,
+			 const struct gbphy_device_id *id)
+{
+	struct gb_connection *connection;
+	struct gb_i2c_device *gb_i2c_dev;
+	struct i2c_adapter *adapter;
+	int ret;
+
+	gb_i2c_dev = kzalloc(sizeof(*gb_i2c_dev), GFP_KERNEL);
+	if (!gb_i2c_dev)
+		return -ENOMEM;
+
+	connection = gb_connection_create(gbphy_dev->bundle,
+					  le16_to_cpu(gbphy_dev->cport_desc->id),
+					  NULL);
+	if (IS_ERR(connection)) {
+		ret = PTR_ERR(connection);
+		goto exit_i2cdev_free;
+	}
+
+	gb_i2c_dev->connection = connection;
+	gb_connection_set_data(connection, gb_i2c_dev);
+	gb_i2c_dev->gbphy_dev = gbphy_dev;
+	gb_gbphy_set_data(gbphy_dev, gb_i2c_dev);
+
+	ret = gb_connection_enable(connection);
+	if (ret)
+		goto exit_connection_destroy;
+
+	ret = gb_i2c_device_setup(gb_i2c_dev);
+	if (ret)
+		goto exit_connection_disable;
+
+	/* Looks good; up our i2c adapter */
+	adapter = &gb_i2c_dev->adapter;
+	adapter->owner = THIS_MODULE;
+	adapter->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
+	adapter->algo = &gb_i2c_algorithm;
+	/* adapter->algo_data = what? */
+
+	adapter->dev.parent = &gbphy_dev->dev;
+	snprintf(adapter->name, sizeof(adapter->name), "Greybus i2c adapter");
+	i2c_set_adapdata(adapter, gb_i2c_dev);
+
+	ret = i2c_add_adapter(adapter);
+	if (ret)
+		goto exit_connection_disable;
+
+	gbphy_runtime_put_autosuspend(gbphy_dev);
+	return 0;
+
+exit_connection_disable:
+	gb_connection_disable(connection);
+exit_connection_destroy:
+	gb_connection_destroy(connection);
+exit_i2cdev_free:
+	kfree(gb_i2c_dev);
+
+	return ret;
+}
+
+static void gb_i2c_remove(struct gbphy_device *gbphy_dev)
+{
+	struct gb_i2c_device *gb_i2c_dev = gb_gbphy_get_data(gbphy_dev);
+	struct gb_connection *connection = gb_i2c_dev->connection;
+	int ret;
+
+	ret = gbphy_runtime_get_sync(gbphy_dev);
+	if (ret)
+		gbphy_runtime_get_noresume(gbphy_dev);
+
+	i2c_del_adapter(&gb_i2c_dev->adapter);
+	gb_connection_disable(connection);
+	gb_connection_destroy(connection);
+	kfree(gb_i2c_dev);
+}
+
+static const struct gbphy_device_id gb_i2c_id_table[] = {
+	{ GBPHY_PROTOCOL(GREYBUS_PROTOCOL_I2C) },
+	{ },
+};
+MODULE_DEVICE_TABLE(gbphy, gb_i2c_id_table);
+
+static struct gbphy_driver i2c_driver = {
+	.name		= "i2c",
+	.probe		= gb_i2c_probe,
+	.remove		= gb_i2c_remove,
+	.id_table	= gb_i2c_id_table,
+};
+
+module_gbphy_driver(i2c_driver);
+MODULE_LICENSE("GPL v2");

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