Hi Richard,
sorry for the late reply.
> > I'm curious if there have ever been any attempts to emulate i2c devices
> > under uml in order to facilitate driver development by using stub
> > drivers.
> I know none.
> If there is a use case, why not. :-)
Thanks for your encouraging words ;)
I had a look around and found the nice CONFIG_I2C_STUB driver,
which is described in detail at
http://www.kernel.org/doc/Documentation/i2c/i2c-stub
"""This module is a very simple fake I2C/SMBus driver. It implements five
types of SMBus commands: write quick, (r/w) byte, (r/w) byte data, (r/w)
word data, and (r/w) I2C block data."""
which more or less exactly fits my need.
The only thing that was missing was general support for I2C which is dependent
on CONFIG_HAS_IOMEM which unfortunately isn't available on UML,
but I simply added a || UML to the Kconfig and was now able to build the I2C
Support, the i2c-dev module (for userspace access) and the i2c-stub driver.
If I know load the i2c_stub module I have a emulated i2c device ;)
I adapted the stub driver to my needs and was now able to create my own
emulated i2c device and start with driver and tools development for it ;)
I added the patch, in case you're interested.
Unfortunately some I2C drivers fail to build if CONFIG_HAS_IOMEM = n, but
don't have that dependency in Kconfig - I simply added it to prevent them from
inclusion.
Do you think I should try to push this mainline via the i2c subsystem?
Thanks,
Peter
From 44d8ec6fa1466c226b605baae9483749ea9de200 Mon Sep 17 00:00:00 2001
From: Peter Huewe <peterhu...@gmx.de>
Date: Sun, 9 Sep 2012 03:03:29 +0200
Subject: [PATCH] i2c: Fix/Change dependencies to make I2C available on UML
This patch overwrites the HAS_IOMEM dependency for I2C on UML, as it is not
really necessary to have HAS_IOMEM in order build the generic I2C part.
In addition to that, every I2C modules available in UML which really
needs HAS_IOMEM was given this dependency to its KConfig.
The I2C subsystem can now be used, e.g. by the i2c-stub driver, for
development of I2C device drivers.
Signed-off-by: Peter Huewe <peterhu...@gmx.de>
---
drivers/i2c/Kconfig | 2 +-
drivers/i2c/busses/Kconfig | 6 ++++--
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 5a3bb3d..03ce0cb 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -4,7 +4,7 @@
menuconfig I2C
tristate "I2C support"
- depends on HAS_IOMEM
+ depends on HAS_IOMEM || UML
select RT_MUTEXES
---help---
I2C (pronounce: I-squared-C) is a slow serial bus protocol used in
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index b4aaa1b..1e61ad9 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -498,7 +498,7 @@ config I2C_NUC900
config I2C_OCORES
tristate "OpenCores I2C Controller"
- depends on EXPERIMENTAL
+ depends on EXPERIMENTAL && HAS_IOMEM
help
If you say yes to this option, support will be included for the
OpenCores I2C controller. For details see
@@ -525,6 +525,7 @@ config I2C_PASEMI
config I2C_PCA_PLATFORM
tristate "PCA9564/PCA9665 as platform device"
+ depends on HAS_IOMEM
select I2C_ALGOPCA
default n
help
@@ -628,6 +629,7 @@ config I2C_SH_MOBILE
config I2C_SIMTEC
tristate "Simtec Generic I2C interface"
+ depends on HAS_IOMEM
select I2C_ALGOBIT
help
If you say yes to this option, support will be included for
@@ -772,7 +774,7 @@ config I2C_PARPORT_LIGHT
config I2C_TAOS_EVM
tristate "TAOS evaluation module"
- depends on EXPERIMENTAL
+ depends on EXPERIMENTAL && HAS_IOMEM
select SERIO
select SERIO_SERPORT
default n
--
1.7.8.6
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