Messages in this thread | | | Date | Sun, 4 Dec 2011 12:47:41 +0100 | From | Wolfram Sang <> | Subject | Re: [PATCH] drivers, char: add U-Boot bootcount driver |
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On Sun, Dec 04, 2011 at 10:45:21AM +0100, Heiko Schocher wrote: > This driver implements the Linux kernel half of the boot count feature - > the boot counter can only be reset after it is clear that the > application has been started and is running correctly, which usually > can only be determined by the application code itself. Thus the reset > of the boot counter must be done by application code, which thus needs > an appropriate driver.
An appropriate mechanism, not necessarily a driver, see below.
> Required feature by the Carrier Grade Linux Requirements Definition; > see for example document "Carrier Grade Linux Requirements Definition > Overview V3.0" at > > http://www.linuxfoundation.org/collaborate/workgroups/cgl/requirements#SMM.6.0_Boot_Cycle_Detection > > Description: OSDL CGL specifies that carrier grade Linux > shall provide support for detecting a repeating reboot cycle > due to recurring failures. This detection should happen in > user space before system services are started.
So, technically, a flag would be enough, not necessarily a counter? Although a counter probably has more advantages...
> This driver provides read/write access to the U-Boot bootcounter > through PROC FS and/or sysFS file.
Why ProcFS? Why ProcFS and/or SysFS? Which has priority? Why not /dev?
> The bootcountregister gets configured via DTS. > for example on the enbw_cmc board: > > bootcount@0x23060 { > compatible = "uboot,bootcount";
No. I assume you are not the vendor of what is at 0x23060, the actual device. Only the device must be encoded in the compatible-entry which then implies the bootcount functionality. Also, keep in mind that your solution should be generic for bootloaders.
> reg = <0x23060 0x20>;
I assume that non-volatile memory would qualify as a boot-counter, so those could be tied to I2C busses etc? reg would not fit then.
I do wonder if it makes more sense to add such functionality to the watchdog-core to save the additional device (CCed). Needs a second thought, though...
Regards,
Wolfram
-- Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | [unhandled content-type:application/pgp-signature] | |