Hi Greg:
* Greg KH <greg at 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 at 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: Mark M. Hoffman <mhoffman at lightlink.com>
diff -Nru linux-2.6.9-rc1/Documentation/i2c/i2c-stub linux-2.6.9-rc1-mmh/Documentation/i2c/i2c-stub
--- linux-2.6.9-rc1/Documentation/i2c/i2c-stub 1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6.9-rc1-mmh/Documentation/i2c/i2c-stub 2004-08-26 22:29:42.744361522 -0400
@@ -0,0 +1,33 @@
+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.
+
diff -Nru linux-2.6.9-rc1/drivers/i2c/busses/i2c-stub.c linux-2.6.9-rc1-mmh/drivers/i2c/busses/i2c-stub.c
--- linux-2.6.9-rc1/drivers/i2c/busses/i2c-stub.c 1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6.9-rc1-mmh/drivers/i2c/busses/i2c-stub.c 2004-08-26 21:43:09.858725620 -0400
@@ -0,0 +1,125 @@
+/*
+ i2c-stub.c - Part of lm_sensors, Linux kernel modules for hardware
+ monitoring
+
+ Copyright (c) 2004 Mark M. Hoffman <mhoffman at 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 at lightlink.com>");
+MODULE_DESCRIPTION("I2C stub driver");
+MODULE_LICENSE("GPL");
+
+module_init(i2c_stub_init);
+module_exit(i2c_stub_exit);
+
diff -Nru linux-2.6.9-rc1/drivers/i2c/busses/Kconfig linux-2.6.9-rc1-mmh/drivers/i2c/busses/Kconfig
--- linux-2.6.9-rc1/drivers/i2c/busses/Kconfig 2004-08-24 09:52:39.000000000 -0400
+++ linux-2.6.9-rc1-mmh/drivers/i2c/busses/Kconfig 2004-08-26 22:00:48.295240107 -0400
@@ -376,6 +376,19 @@
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
diff -Nru linux-2.6.9-rc1/drivers/i2c/busses/Makefile linux-2.6.9-rc1-mmh/drivers/i2c/busses/Makefile
--- linux-2.6.9-rc1/drivers/i2c/busses/Makefile 2004-08-24 09:52:39.000000000 -0400
+++ linux-2.6.9-rc1-mmh/drivers/i2c/busses/Makefile 2004-08-26 21:44:13.404549498 -0400
@@ -30,6 +30,7 @@
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-$(CONFIG_I2C_VIA) += i2c-via.o
obj-$(CONFIG_I2C_VIAPRO) += i2c-viapro.o
obj-$(CONFIG_I2C_VOODOO3) += i2c-voodoo3.o
--
Mark M. Hoffman
mhoffman at lightlink.com
