linux/drivers/i2c/busses/i2c-stub.c
Jean Delvare 3401b2fff3 i2c: Let bus drivers add SPD to their class
Let general purpose I2C/SMBus bus drivers add SPD to their class. Once
this is done, we will be able to tell the eeprom driver to only probe
for SPD EEPROMs and similar on these buses.

Note that I took a conservative approach here, adding I2C_CLASS_SPD to
many drivers that have no idea whether they can host SPD EEPROMs or not.
This is to make sure that the eeprom driver doesn't stop probing buses
where SPD EEPROMs or equivalent live.

So, bus driver maintainers and users should feel free to remove the SPD
class from drivers those buses never have SPD EEPROMs or they don't
want the eeprom driver to bind to them. Likewise, feel free to add the
SPD class to any bus driver I might have missed.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-07-14 22:38:29 +02:00

193 lines
4.8 KiB
C

/*
i2c-stub.c - I2C/SMBus chip emulator
Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>
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; either version 2 of the License, or
(at your option) any later version.
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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#define DEBUG 1
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#define MAX_CHIPS 10
static unsigned short chip_addr[MAX_CHIPS];
module_param_array(chip_addr, ushort, NULL, S_IRUGO);
MODULE_PARM_DESC(chip_addr,
"Chip addresses (up to 10, between 0x03 and 0x77)");
struct stub_chip {
u8 pointer;
u16 words[256]; /* Byte operations use the LSB as per SMBus
specification */
};
static struct stub_chip *stub_chips;
/* Return negative errno on error. */
static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
char read_write, u8 command, int size, union i2c_smbus_data * data)
{
s32 ret;
int i;
struct stub_chip *chip = NULL;
/* Search for the right chip */
for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
if (addr == chip_addr[i]) {
chip = stub_chips + i;
break;
}
}
if (!chip)
return -ENODEV;
switch (size) {
case I2C_SMBUS_QUICK:
dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr);
ret = 0;
break;
case I2C_SMBUS_BYTE:
if (read_write == I2C_SMBUS_WRITE) {
chip->pointer = command;
dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
"wrote 0x%02x.\n",
addr, command);
} else {
data->byte = chip->words[chip->pointer++] & 0xff;
dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
"read 0x%02x.\n",
addr, data->byte);
}
ret = 0;
break;
case I2C_SMBUS_BYTE_DATA:
if (read_write == I2C_SMBUS_WRITE) {
chip->words[command] &= 0xff00;
chip->words[command] |= data->byte;
dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
"wrote 0x%02x at 0x%02x.\n",
addr, data->byte, command);
} else {
data->byte = chip->words[command] & 0xff;
dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
"read 0x%02x at 0x%02x.\n",
addr, data->byte, command);
}
chip->pointer = command + 1;
ret = 0;
break;
case I2C_SMBUS_WORD_DATA:
if (read_write == I2C_SMBUS_WRITE) {
chip->words[command] = data->word;
dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
"wrote 0x%04x at 0x%02x.\n",
addr, data->word, command);
} else {
data->word = chip->words[command];
dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
"read 0x%04x at 0x%02x.\n",
addr, data->word, command);
}
ret = 0;
break;
default:
dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
ret = -EOPNOTSUPP;
break;
} /* switch (size) */
return ret;
}
static u32 stub_func(struct i2c_adapter *adapter)
{
return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA;
}
static const struct i2c_algorithm smbus_algorithm = {
.functionality = stub_func,
.smbus_xfer = stub_xfer,
};
static struct i2c_adapter stub_adapter = {
.owner = THIS_MODULE,
.class = I2C_CLASS_HWMON | I2C_CLASS_SPD,
.algo = &smbus_algorithm,
.name = "SMBus stub driver",
};
static int __init i2c_stub_init(void)
{
int i, ret;
if (!chip_addr[0]) {
printk(KERN_ERR "i2c-stub: Please specify a chip address\n");
return -ENODEV;
}
for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) {
printk(KERN_ERR "i2c-stub: Invalid chip address "
"0x%02x\n", chip_addr[i]);
return -EINVAL;
}
printk(KERN_INFO "i2c-stub: Virtual chip at 0x%02x\n",
chip_addr[i]);
}
/* Allocate memory for all chips at once */
stub_chips = kzalloc(i * sizeof(struct stub_chip), GFP_KERNEL);
if (!stub_chips) {
printk(KERN_ERR "i2c-stub: Out of memory\n");
return -ENOMEM;
}
ret = i2c_add_adapter(&stub_adapter);
if (ret)
kfree(stub_chips);
return ret;
}
static void __exit i2c_stub_exit(void)
{
i2c_del_adapter(&stub_adapter);
kfree(stub_chips);
}
MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
MODULE_DESCRIPTION("I2C stub driver");
MODULE_LICENSE("GPL");
module_init(i2c_stub_init);
module_exit(i2c_stub_exit);