Commit b9cdad74 authored by Jean Delvare's avatar Jean Delvare Committed by Jean Delvare
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i2c: New bus driver for the TAOS evaluation modules



This is a new I2C bus driver for the TAOS evaluation modules. Developped
and tested on the TAOS TSL2550 EVM.
Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent 7edcb9ab
Kernel driver i2c-taos-evm
Author: Jean Delvare <khali@linux-fr.org>
This is a driver for the evaluation modules for TAOS I2C/SMBus chips.
The modules include an SMBus master with limited capabilities, which can
be controlled over the serial port. Virtually all evaluation modules
are supported, but a few lines of code need to be added for each new
module to instantiate the right I2C chip on the bus. Obviously, a driver
for the chip in question is also needed.
Currently supported devices are:
* TAOS TSL2550 EVM
For addtional information on TAOS products, please see
http://www.taosinc.com/
Using this driver
-----------------
In order to use this driver, you'll need the serport driver, and the
inputattach tool, which is part of the input-utils package. The following
commands will tell the kernel that you have a TAOS EVM on the first
serial port:
# modprobe serport
# inputattach --taos-evm /dev/ttyS0
Technical details
-----------------
Only 4 SMBus transaction types are supported by the TAOS evaluation
modules:
* Receive Byte
* Send Byte
* Read Byte
* Write Byte
The communication protocol is text-based and pretty simple. It is
described in a PDF document on the CD which comes with the evaluation
module. The communication is rather slow, because the serial port has
to operate at 1200 bps. However, I don't think this is a big concern in
practice, as these modules are meant for evaluation and testing only.
......@@ -513,6 +513,22 @@ config I2C_SIS96X
This driver can also be built as a module. If so, the module
will be called i2c-sis96x.
config I2C_TAOS_EVM
tristate "TAOS evaluation module"
depends on EXPERIMENTAL
select SERIO
select SERIO_SERPORT
default n
help
This supports TAOS evaluation modules on serial port. In order to
use this driver, you will need the inputattach tool, which is part
of the input-utils package.
If unsure, say N.
This support is also available as a module. If so, the module
will be called i2c-taos-evm.
config I2C_STUB
tristate "I2C/SMBus Test Stub"
depends on EXPERIMENTAL && m
......
......@@ -44,6 +44,7 @@ obj-$(CONFIG_I2C_SIS5595) += i2c-sis5595.o
obj-$(CONFIG_I2C_SIS630) += i2c-sis630.o
obj-$(CONFIG_I2C_SIS96X) += i2c-sis96x.o
obj-$(CONFIG_I2C_STUB) += i2c-stub.o
obj-$(CONFIG_I2C_TAOS_EVM) += i2c-taos-evm.o
obj-$(CONFIG_I2C_TINY_USB) += i2c-tiny-usb.o
obj-$(CONFIG_I2C_VERSATILE) += i2c-versatile.o
obj-$(CONFIG_I2C_ACORN) += i2c-acorn.o
......
/*
* Driver for the TAOS evaluation modules
* These devices include an I2C master which can be controlled over the
* serial port.
*
* Copyright (C) 2007 Jean Delvare <khali@linux-fr.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/input.h>
#include <linux/serio.h>
#include <linux/init.h>
#include <linux/i2c.h>
#define TAOS_BUFFER_SIZE 63
#define TAOS_STATE_INIT 0
#define TAOS_STATE_IDLE 1
#define TAOS_STATE_SEND 2
#define TAOS_STATE_RECV 3
#define TAOS_CMD_RESET 0x12
static DECLARE_WAIT_QUEUE_HEAD(wq);
struct taos_data {
struct i2c_adapter adapter;
struct i2c_client *client;
int state;
u8 addr; /* last used address */
unsigned char buffer[TAOS_BUFFER_SIZE];
unsigned int pos; /* position inside the buffer */
};
/* TAOS TSL2550 EVM */
static struct i2c_board_info tsl2550_info = {
I2C_BOARD_INFO("tsl2550", 0x39),
.type = "tsl2550",
};
/* Instantiate i2c devices based on the adapter name */
static struct i2c_client *taos_instantiate_device(struct i2c_adapter *adapter)
{
if (!strncmp(adapter->name, "TAOS TSL2550 EVM", 16)) {
dev_info(&adapter->dev, "Instantiating device %s at 0x%02x\n",
tsl2550_info.driver_name, tsl2550_info.addr);
return i2c_new_device(adapter, &tsl2550_info);
}
return NULL;
}
static int taos_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
unsigned short flags, char read_write, u8 command,
int size, union i2c_smbus_data *data)
{
struct serio *serio = adapter->algo_data;
struct taos_data *taos = serio_get_drvdata(serio);
char *p;
/* Encode our transaction. "@" is for the device address, "$" for the
SMBus command and "#" for the data. */
p = taos->buffer;
/* The device remembers the last used address, no need to send it
again if it's the same */
if (addr != taos->addr)
p += sprintf(p, "@%02X", addr);
switch (size) {
case I2C_SMBUS_BYTE:
if (read_write == I2C_SMBUS_WRITE)
sprintf(p, "$#%02X", command);
else
sprintf(p, "$");
break;
case I2C_SMBUS_BYTE_DATA:
if (read_write == I2C_SMBUS_WRITE)
sprintf(p, "$%02X#%02X", command, data->byte);
else
sprintf(p, "$%02X", command);
break;
default:
dev_dbg(&adapter->dev, "Unsupported transaction size %d\n",
size);
return -EINVAL;
}
/* Send the transaction to the TAOS EVM */
dev_dbg(&adapter->dev, "Command buffer: %s\n", taos->buffer);
taos->pos = 0;
taos->state = TAOS_STATE_SEND;
serio_write(serio, taos->buffer[0]);
wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
msecs_to_jiffies(250));
if (taos->state != TAOS_STATE_IDLE) {
dev_err(&adapter->dev, "Transaction failed "
"(state=%d, pos=%d)\n", taos->state, taos->pos);
taos->addr = 0;
return -EIO;
}
taos->addr = addr;
/* Start the transaction and read the answer */
taos->pos = 0;
taos->state = TAOS_STATE_RECV;
serio_write(serio, read_write == I2C_SMBUS_WRITE ? '>' : '<');
wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
msecs_to_jiffies(150));
if (taos->state != TAOS_STATE_IDLE
|| taos->pos != 6) {
dev_err(&adapter->dev, "Transaction timeout (pos=%d)\n",
taos->pos);
return -EIO;
}
dev_dbg(&adapter->dev, "Answer buffer: %s\n", taos->buffer);
/* Interpret the returned string */
p = taos->buffer + 2;
p[3] = '\0';
if (!strcmp(p, "NAK"))
return -ENODEV;
if (read_write == I2C_SMBUS_WRITE) {
if (!strcmp(p, "ACK"))
return 0;
} else {
if (p[0] == 'x') {
data->byte = simple_strtol(p + 1, NULL, 16);
return 0;
}
}
return -EIO;
}
static u32 taos_smbus_func(struct i2c_adapter *adapter)
{
return I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA;
}
static const struct i2c_algorithm taos_algorithm = {
.smbus_xfer = taos_smbus_xfer,
.functionality = taos_smbus_func,
};
static irqreturn_t taos_interrupt(struct serio *serio, unsigned char data,
unsigned int flags)
{
struct taos_data *taos = serio_get_drvdata(serio);
switch (taos->state) {
case TAOS_STATE_INIT:
taos->buffer[taos->pos++] = data;
if (data == ':'
|| taos->pos == TAOS_BUFFER_SIZE - 1) {
taos->buffer[taos->pos] = '\0';
taos->state = TAOS_STATE_IDLE;
wake_up_interruptible(&wq);
}
break;
case TAOS_STATE_SEND:
if (taos->buffer[++taos->pos])
serio_write(serio, taos->buffer[taos->pos]);
else {
taos->state = TAOS_STATE_IDLE;
wake_up_interruptible(&wq);
}
break;
case TAOS_STATE_RECV:
taos->buffer[taos->pos++] = data;
if (data == ']') {
taos->buffer[taos->pos] = '\0';
taos->state = TAOS_STATE_IDLE;
wake_up_interruptible(&wq);
}
break;
}
return IRQ_HANDLED;
}
/* Extract the adapter name from the buffer received after reset.
The buffer is modified and a pointer inside the buffer is returned. */
static char *taos_adapter_name(char *buffer)
{
char *start, *end;
start = strstr(buffer, "TAOS ");
if (!start)
return NULL;
end = strchr(start, '\r');
if (!end)
return NULL;
*end = '\0';
return start;
}
static int taos_connect(struct serio *serio, struct serio_driver *drv)
{
struct taos_data *taos;
struct i2c_adapter *adapter;
char *name;
int err;
taos = kzalloc(sizeof(struct taos_data), GFP_KERNEL);
if (!taos) {
err = -ENOMEM;
goto exit;
}
taos->state = TAOS_STATE_INIT;
serio_set_drvdata(serio, taos);
err = serio_open(serio, drv);
if (err)
goto exit_kfree;
adapter = &taos->adapter;
adapter->owner = THIS_MODULE;
adapter->algo = &taos_algorithm;
adapter->algo_data = serio;
adapter->dev.parent = &serio->dev;
/* Reset the TAOS evaluation module to identify it */
serio_write(serio, TAOS_CMD_RESET);
wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
msecs_to_jiffies(2000));
if (taos->state != TAOS_STATE_IDLE) {
err = -ENODEV;
dev_dbg(&serio->dev, "TAOS EVM reset failed (state=%d, "
"pos=%d)\n", taos->state, taos->pos);
goto exit_close;
}
name = taos_adapter_name(taos->buffer);
if (!name) {
err = -ENODEV;
dev_err(&serio->dev, "TAOS EVM identification failed\n");
goto exit_close;
}
strlcpy(adapter->name, name, sizeof(adapter->name));
err = i2c_add_adapter(adapter);
if (err)
goto exit_close;
dev_dbg(&serio->dev, "Connected to TAOS EVM\n");
taos->client = taos_instantiate_device(adapter);
return 0;
exit_close:
serio_close(serio);
exit_kfree:
serio_set_drvdata(serio, NULL);
kfree(taos);
exit:
return err;
}
static void taos_disconnect(struct serio *serio)
{
struct taos_data *taos = serio_get_drvdata(serio);
if (taos->client)
i2c_unregister_device(taos->client);
i2c_del_adapter(&taos->adapter);
serio_close(serio);
serio_set_drvdata(serio, NULL);
kfree(taos);
dev_dbg(&serio->dev, "Disconnected from TAOS EVM\n");
}
static struct serio_device_id taos_serio_ids[] = {
{
.type = SERIO_RS232,
.proto = SERIO_TAOSEVM,
.id = SERIO_ANY,
.extra = SERIO_ANY,
},
{ 0 }
};
MODULE_DEVICE_TABLE(serio, taos_serio_ids);
static struct serio_driver taos_drv = {
.driver = {
.name = "taos-evm",
},
.description = "TAOS evaluation module driver",
.id_table = taos_serio_ids,
.connect = taos_connect,
.disconnect = taos_disconnect,
.interrupt = taos_interrupt,
};
static int __init taos_init(void)
{
return serio_register_driver(&taos_drv);
}
static void __exit taos_exit(void)
{
serio_unregister_driver(&taos_drv);
}
MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
MODULE_DESCRIPTION("TAOS evaluation module driver");
MODULE_LICENSE("GPL");
module_init(taos_init);
module_exit(taos_exit);
......@@ -209,5 +209,6 @@ static inline void serio_unpin_driver(struct serio *serio)
#define SERIO_PENMOUNT 0x31
#define SERIO_TOUCHRIGHT 0x32
#define SERIO_TOUCHWIN 0x33
#define SERIO_TAOSEVM 0x34
#endif
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