Messages in this thread | | | From | Pali Rohár <> | Date | Tue, 1 Nov 2011 13:53:26 +0100 | Subject | Re: [PATCH 8/9] bq27x00: Add miscdevice for each battery with ioctl for reading registers |
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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/
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