linux-kernel - Reading temperature from another Kernel modules

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Date:	Tue, 26 Oct 2010 11:01:56 +0200
From:	Matthias Dunda <user254@...17.greatnet.de>
To:	linux-kernel@...r.kernel.org
Subject: Reading temperature from another Kernel modules

Hi everybody,

I need to read out the current system temperature from inside my custom kernel module.

My system works with the jc42.c driver and I can read the temperature perfectly via the proc filesystem in user space.

How do I query the temperature from another kernel driver?

First of all I added a new function and exported the symbol

int jc42_get_temperature()
{
   int temp;
   // TODO get the correct temp
   temp = jc42_read_value(my_local_client, JC42_REG_TEMP);
   return temp;
}
EXPORT_SYMBOL(jc42_get_temperature);

BUT: how do I get the temp? Most of the internal functions require a struct device or a struct i2c_client, which - I assume - are perfectly provided by the kernel when going the way over the proc file system.

I tried to statically save such a struct during the probing process (this is the above my_local_client), but this works neither. When I use the saved struct to call jc42_read_value, I always get a temperature value which is not correct at all.

Kernel is 2.6.29.6-rt24 (yes, jc42 is originally not included there - we ported it from a newer kernel release.)

Thanks for any help!
Matthias

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