drivers/staging/greybus/i2c.c - linux - Git at Google

 /*
  * 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"

 struct gb_i2c_device {
 	struct gb_connection	*connection;

 	u32			functionality;
 	u16			timeout_msec;
 	u8			retries;

 	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;
 }

 static int gb_i2c_timeout_operation(struct gb_i2c_device *gb_i2c_dev, u16 msec)
 {
 	struct gb_i2c_timeout_request request;
 	int ret;

 	request.msec = cpu_to_le16(msec);
 	ret = gb_operation_sync(gb_i2c_dev->connection, GB_I2C_TYPE_TIMEOUT,
 				&request, sizeof(request), NULL, 0);
 	if (ret)
 		pr_err("timeout operation failed (%d)\n", ret);
 	else
 		gb_i2c_dev->timeout_msec = msec;

 	return ret;
 }

 static int gb_i2c_retries_operation(struct gb_i2c_device *gb_i2c_dev,
 				u8 retries)
 {
 	struct gb_i2c_retries_request request;
 	int ret;

 	request.retries = retries;
 	ret = gb_operation_sync(gb_i2c_dev->connection, GB_I2C_TYPE_RETRIES,
 				&request, sizeof(request), NULL, 0);
 	if (ret)
 		pr_err("retries operation failed (%d)\n", ret);
 	else
 		gb_i2c_dev->retries = retries;

 	return ret;
 }


 /*
  * 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_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(&connection->bundle->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 gb_operation *operation;
 	int ret;

 	operation = gb_i2c_operation_create(connection, msgs, msg_count);
 	if (!operation)
 		return -ENOMEM;

 	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)) {
 		pr_err("transfer operation failed (%d)\n", ret);
 	}

 	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, and
  * set up the retry count and timeout.
  *
  * Note: gb_i2c_dev->connection is assumed to have been valid.
  */
 static int gb_i2c_device_setup(struct gb_i2c_device *gb_i2c_dev)
 {
 	int ret;

 	/* Assume the functionality never changes, just get it once */
 	ret = gb_i2c_functionality_operation(gb_i2c_dev);
 	if (ret)
 		return ret;

 	/* Set up our default retry count and timeout */
 	ret = gb_i2c_retries_operation(gb_i2c_dev, GB_I2C_RETRIES_DEFAULT);
 	if (ret)
 		return ret;

 	return gb_i2c_timeout_operation(gb_i2c_dev, GB_I2C_TIMEOUT_DEFAULT);
 }

 static int gb_i2c_connection_init(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;

 	gb_i2c_dev->connection = connection;	/* refcount? */
 	connection->private = gb_i2c_dev;

 	ret = gb_i2c_device_setup(gb_i2c_dev);
 	if (ret)
 		goto out_err;

 	/* 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->timeout = gb_i2c_dev->timeout_msec * HZ / 1000;
 	adapter->retries = gb_i2c_dev->retries;

 	adapter->dev.parent = &connection->bundle->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 out_err;

 	return 0;
 out_err:
 	/* kref_put(gb_i2c_dev->connection) */
 	kfree(gb_i2c_dev);

 	return ret;
 }

 static void gb_i2c_connection_exit(struct gb_connection *connection)
 {
 	struct gb_i2c_device *gb_i2c_dev = connection->private;

 	i2c_del_adapter(&gb_i2c_dev->adapter);
 	/* kref_put(gb_i2c_dev->connection) */
 	kfree(gb_i2c_dev);
 }

 static struct gb_protocol i2c_protocol = {
 	.name			= "i2c",
 	.id			= GREYBUS_PROTOCOL_I2C,
 	.major			= GB_I2C_VERSION_MAJOR,
 	.minor			= GB_I2C_VERSION_MINOR,
 	.connection_init	= gb_i2c_connection_init,
 	.connection_exit	= gb_i2c_connection_exit,
 	.request_recv		= NULL,	/* no incoming requests */
 };

 gb_builtin_protocol_driver(i2c_protocol);
	/*
	* 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"

	struct gb_i2c_device {
	struct gb_connection *connection;

	u32 functionality;
	u16 timeout_msec;
	u8 retries;

	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;
	}

	static int gb_i2c_timeout_operation(struct gb_i2c_device *gb_i2c_dev, u16 msec)
	{
	struct gb_i2c_timeout_request request;
	int ret;

	request.msec = cpu_to_le16(msec);
	ret = gb_operation_sync(gb_i2c_dev->connection, GB_I2C_TYPE_TIMEOUT,
	&request, sizeof(request), NULL, 0);
	if (ret)
	pr_err("timeout operation failed (%d)\n", ret);
	else
	gb_i2c_dev->timeout_msec = msec;

	return ret;
	}

	static int gb_i2c_retries_operation(struct gb_i2c_device *gb_i2c_dev,
	u8 retries)
	{
	struct gb_i2c_retries_request request;
	int ret;

	request.retries = retries;
	ret = gb_operation_sync(gb_i2c_dev->connection, GB_I2C_TYPE_RETRIES,
	&request, sizeof(request), NULL, 0);
	if (ret)
	pr_err("retries operation failed (%d)\n", ret);
	else
	gb_i2c_dev->retries = retries;

	return ret;
	}


	/*
	* 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_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(&connection->bundle->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 gb_operation *operation;
	int ret;

	operation = gb_i2c_operation_create(connection, msgs, msg_count);
	if (!operation)
	return -ENOMEM;

	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)) {
	pr_err("transfer operation failed (%d)\n", ret);
	}

	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, and
	* set up the retry count and timeout.
	*
	* Note: gb_i2c_dev->connection is assumed to have been valid.
	*/
	static int gb_i2c_device_setup(struct gb_i2c_device *gb_i2c_dev)
	{
	int ret;

	/* Assume the functionality never changes, just get it once */
	ret = gb_i2c_functionality_operation(gb_i2c_dev);
	if (ret)
	return ret;

	/* Set up our default retry count and timeout */
	ret = gb_i2c_retries_operation(gb_i2c_dev, GB_I2C_RETRIES_DEFAULT);
	if (ret)
	return ret;

	return gb_i2c_timeout_operation(gb_i2c_dev, GB_I2C_TIMEOUT_DEFAULT);
	}

	static int gb_i2c_connection_init(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;

	gb_i2c_dev->connection = connection; /* refcount? */
	connection->private = gb_i2c_dev;

	ret = gb_i2c_device_setup(gb_i2c_dev);
	if (ret)
	goto out_err;

	/* 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->timeout = gb_i2c_dev->timeout_msec * HZ / 1000;
	adapter->retries = gb_i2c_dev->retries;

	adapter->dev.parent = &connection->bundle->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 out_err;

	return 0;
	out_err:
	/* kref_put(gb_i2c_dev->connection) */
	kfree(gb_i2c_dev);

	return ret;
	}

	static void gb_i2c_connection_exit(struct gb_connection *connection)
	{
	struct gb_i2c_device *gb_i2c_dev = connection->private;

	i2c_del_adapter(&gb_i2c_dev->adapter);
	/* kref_put(gb_i2c_dev->connection) */
	kfree(gb_i2c_dev);
	}

	static struct gb_protocol i2c_protocol = {
	.name = "i2c",
	.id = GREYBUS_PROTOCOL_I2C,
	.major = GB_I2C_VERSION_MAJOR,
	.minor = GB_I2C_VERSION_MINOR,
	.connection_init = gb_i2c_connection_init,
	.connection_exit = gb_i2c_connection_exit,
	.request_recv = NULL, /* no incoming requests */
	};

	gb_builtin_protocol_driver(i2c_protocol);