blob: 5a5af36570c876bbc8192e7b7506d9114c342ed4 [file] [log] [blame]
/*
* 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);