Ok so, I grabbed the kernel source, built and installed kernel with
loadable module support and had it built the i2c modules. I then
insmod the i2c-dev.ko and it worked fine. It created a character
special file 89 0 under /dev/i2c-0.
I can open the file just fine with file = open("/dev/i2c-0", O_RDWR),
however the ioctl(file, I2C_SLAVE, address) fails with error code -1.
I looked at (i think) error.h and all errors were positive. I have not
been able to find a list of ioctl error codes, nor do I know what I am
doing wrong here.
Also, a big thanks to everyone here, you pointed me in the right
direction and helped me out!
On Oct 30, 7:18 am, Deva R <[email protected]> wrote:
> now, what exactly is the blocking issue?
>
> On Wed, Oct 27, 2010 at 10:30 PM, shootingatshadow <
>
> [email protected]> wrote:
> > Thanks for your help, I spent the last few weeks doing more research
> > and am still stuck.
>
> > 1.) I went to The Linux Documentation Project, and was unable to find
> > anything on I2C development, any suggestions on where to go would be
> > appreciated.
>
> its right in ./Documentation/i2c folder.. did u miss more than
> that?http://lxr.linux.no/linux+v2.6.36/Documentation/i2c/dev-interface
>
>
>
> > 2.) My second question, is that the i2c-dev.h header, which from my
> > understanding is required for user space i2c access, is distributed in
> > the lm-sensors project for Debian based systems. Is their an
> > alternative for an Arm based Android system?
>
> <linux/*.h> are generic headers which are platform agnostic..
> if at all a header is architecture specific (say cpu.h, cache.h) - goes into
> arch/x86/include/asm/, arch/arm/include/asm/
>
> only platform specific driver implementation goes under ./arch/arm/<>/<i2c>
>
>
>
> > Thanks again!
>
> > On Oct 13, 2:15 am, kavitha bk <[email protected]> wrote:
> > > Hi,
> > > U can go through Linux Documentation for i2c
> > > Plain I2C communication
> > > -----------------------
> > > int i2c_master_send(struct i2c_client *client, const char *buf,
> > > int count);
> > > int i2c_master_recv(struct i2c_client *client, char *buf, int
> > > count);
> > > These routines read and write some bytes from/to a client. The client
> > > contains the i2c address, so you do not have to include it. The second
> > > parameter contains the bytes to read/write, the third the number of bytes
> > > to read/write (must be less than the length of the buffer.) Returned is
> > > the actual number of bytes read/written.
> > > int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msg,
> > > int num);
> > > This is if u r doing from kernel.
>
> > > If u want to communicate to a i2c device from user space
>
> > > I2C device files are character device files with major device number
> > > 89 and a minor device number corresponding to the number assigned as
> > > explained above. They should be called "i2c-%d" (i2c-0, i2c-1, ...,
>
> > > i2c-10, ...). All 256 minor device numbers are reserved for i2c.
>
> > > Usually, i2c devices are controlled by a kernel driver. But it is also
> > > possible to access all devices on an adapter from userspace, through
> > > the /dev interface. You need to load module i2c-dev for this.
>
> > > Each registered i2c adapter gets a number, counting from 0. You can
> > > examine /sys/class/i2c-dev/ to see what number corresponds to which
> > > adapter.
>
> > > int file = open(/dev/i2c-0, O_RDWR);
>
> > > When you have opened the device, you must specify with what device
> > > address you want to communicate:
>
> > > int addr = 0x40; /* The I2C address */
>
> > > ioctl(file, I2C_SLAVE, addr)
>
> > > Then u can communicate with the device
>
> > > Regards,
>
> > > Kavitha
>
> > > On Tue, Oct 12, 2010 at 5:42 PM, shootingatshadow <
> > [email protected]
>
> > > > wrote:
> > > > I am a bit new to Linux device drivers, been doing some research and
> > > > trying things out. (Read Linux Device Drivers Book, digging around
> > > > forums)
>
> > > > So I have found at i2c address 0x38 a chip which I would like to talk
> > > > to. There is already a driver in place for that chip. I have the spec
> > > > sheet in hand for that chip as well. However, the device shows up
> > > > under /proc/bus and in the devices file. How can I access this device
> > > > and send it information? My only other experience is opening a file
> > > > under /dev/DEVICE and read and write bytes to it, any suggestions
> > > > would be greatly appreciated.
>
> > > > --
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> > > > [email protected]<android-porting%[email protected]>
> > <android-porting%[email protected]<android-porting%[email protected]>
>
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>
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> --
> Regards,
> Devawww.bittoggler.com
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