Commit 0edcebec authored by Mark M. Hoffman's avatar Mark M. Hoffman Committed by Greg Kroah-Hartman

[PATCH] I2C/SMBus stub for driver testing

* Greg KH <greg@kroah.com> [2004-08-24 16:44:32 -0700]:
> > > Why not?  It looks useful to me.  Care to send me a patch adding
> > > this to the main kernel tree?

* Mark M. Hoffman <mhoffman@lightlink.com> [2004-08-25 10:25:02 -0400]:
> Later today, sure.

Well here it is, one day later because I really didn't want to do this
with printk.  I spent some time looking around and relayfs seems like
a good fit.  Do you think relayfs will ever get merged?  Meanwhile...

* * * * *

This patch, applied to 2.6.9-rc1, adds an I2C/SMBus test stub that is useful
for developing sensors drivers.
Signed-off-by: default avatarMark M. Hoffman <mhoffman@lightlink.com>
Signed-off-by: default avatarGreg Kroah-Hartman <greg@kroah.com>
parent 14188442
MODULE: i2c-stub
DESCRIPTION:
This module is a very simple fake I2C/SMBus driver. It implements three
types of SMBus commands: write quick, (r/w) byte data, and (r/w) word data.
No hardware is needed nor associated with this module. It will accept write
quick commands to all addresses; it will respond to the other commands (also
to all addresses) by reading from or writing to an array in memory. It will
also spam the kernel logs for every command it handles.
The typical use-case is like this:
1. load this module
2. use i2cset (from lm_sensors project) to pre-load some data
3. load the target sensors chip driver module
4. observe its behavior in the kernel log
CAVEATS:
There are independent arrays for byte/data and word/data commands. Depending
on if/how a target driver mixes them, you'll need to be careful.
If your target driver polls some byte or word waiting for it to change, the
stub could lock it up. Use i2cset to unlock it.
If the hardware for your driver has banked registers (e.g. Winbond sensors
chips) this module will not work well - although it could be extended to
support that pretty easily.
If you spam it hard enough, printk can be lossy. This module really wants
something like relayfs.
......@@ -376,6 +376,19 @@ config I2C_SIS96X
This driver can also be built as a module. If so, the module
will be called i2c-sis96x.
config I2C_STUB
tristate "I2C/SMBus Test Stub"
depends on I2C && EXPERIMENTAL && 'm'
default 'n'
help
This module may be useful to developers of SMBus client drivers,
especially for certain kinds of sensor chips.
If you do build this module, be sure to read the notes and warnings
in Documentation/i2c/i2c-stub.
If you don't know what to do here, definitely say N.
config I2C_VIA
tristate "VIA 82C586B"
depends on I2C && PCI && EXPERIMENTAL
......
......@@ -30,6 +30,7 @@ obj-$(CONFIG_I2C_SAVAGE4) += i2c-savage4.o
obj-$(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_VIA) += i2c-via.o
obj-$(CONFIG_I2C_VIAPRO) += i2c-viapro.o
obj-$(CONFIG_I2C_VOODOO3) += i2c-voodoo3.o
......
/*
i2c-stub.c - Part of lm_sensors, Linux kernel modules for hardware
monitoring
Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>
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/config.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/i2c.h>
static u8 stub_bytes[256];
static u16 stub_words[256];
/* Return -1 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;
switch (size) {
case I2C_SMBUS_QUICK:
dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr);
ret = 0;
break;
case I2C_SMBUS_BYTE_DATA:
if (read_write == I2C_SMBUS_WRITE) {
stub_bytes[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 = stub_bytes[command];
dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
"read 0x%02x at 0x%02x.\n",
addr, data->byte, command);
}
ret = 0;
break;
case I2C_SMBUS_WORD_DATA:
if (read_write == I2C_SMBUS_WRITE) {
stub_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 = stub_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 = -1;
break;
} /* switch (size) */
return ret;
}
static u32 stub_func(struct i2c_adapter *adapter)
{
return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE_DATA |
I2C_FUNC_SMBUS_WORD_DATA;
}
static struct i2c_algorithm smbus_algorithm = {
.name = "Non-I2C SMBus adapter",
.id = I2C_ALGO_SMBUS,
.functionality = stub_func,
.smbus_xfer = stub_xfer,
};
static struct i2c_adapter stub_adapter = {
.owner = THIS_MODULE,
.class = I2C_CLASS_HWMON,
.algo = &smbus_algorithm,
.name = "SMBus stub driver",
};
static int __init i2c_stub_init(void)
{
printk(KERN_INFO "i2c-stub loaded\n");
return i2c_add_adapter(&stub_adapter);
}
static void __exit i2c_stub_exit(void)
{
i2c_del_adapter(&stub_adapter);
}
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);
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