lkml.org 
[lkml]   [2011]   [Nov]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 8/9] bq27x00: Add miscdevice for each battery with ioctl for reading registers
2011/11/1 Lars-Peter Clausen <lars@metafoo.de>:
> On 11/01/2011 01:23 PM, Pali Rohár wrote:
>> 2011/11/1 Lars-Peter Clausen <lars@metafoo.de>:
>>> On 11/01/2011 01:43 AM, Pali Rohár wrote:
>>>> * When bq27x00_battery module is loaded it take control of bq27200 i2c battery chip and then it is not possible to use i2cget program from user space (returns -EBUSY)
>>>> * This patch adds new miscdevice for each battery which has ioctl BQ27X00_READ_REG for reading battery registers from user space
>>>>
>>>> * ioctl cmd:
>>>>   #define BQ27X00_READ_REG _IO(MISC_MAJOR, 0)
>>>>
>>>> * ioctl arg:
>>>>   struct bq27x00_reg_parms {
>>>>     int reg; /* battery register (in) */
>>>>     int single; /* 1 - 8bit register, 0 - 16bit register (in) */
>>>>     int ret; /* register status, negative indicate error (out) */
>>>>   };
>>>>
>>>> Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
>>>
>>> I'm not sure if this is such a good idea. Why do you need to read the registers
>>> from userspace? Shouldn't all relevant information be available in a
>>> standardized format through the power_supply userspace API? If you want to use
>>> it for debugging it might be a better idea to provide a debugfs file.
>>>
>>> - Lars
>>>
>>
>> bq27200 chip has a lot of registers (for diagnostic) which is usefull
>> on Nokia N900. power_supply interface is not very abstract to handle
>> all of them.
>
> Which registers are we talking about here. And if this generally useful
> information does it make sense to add a new property to the power_supply interface?

I think it is usefull only for bq, see shell script
http://enivax.net/jk/n900/bq.tar

>
>> Also on Nokia N900 is needed proprietary pogram BME for
>> battery charging which need to access to bq27200 registers. A simple
>> LD_PRELOAD library which wrap i2c-dev access to this device provided
>> by this patch is here:
>> https://code.launchpad.net/~pali/+junk/maemo_libbqioctl
>
> Yes, but that really is a hack to work around the closed source nature of the
> BME program. I don't think we should put such hacks into the kernel.
>

Not only BME. All programs (and shell scripts and all which use
i2cget) need this interface, bacuse loading bq module will block
ic2-dev.

--
Pali Rohár
pali.rohar@gmail.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2011-11-01 13:57    [W:0.049 / U:12.444 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site