Hi, On 27/04/2015 at 15:59:46 +0200, Juergen Borleis wrote : > The built-in RTC unit on some i.MX SoCs isn't an RTC only. It is also a tamper > monitor unit which can keep some (secret) keys. When it does its tamper > detection job and a security violation is detected, the whole DryICE unit > including the real-time counter locks completely. In this state the whole unit > is completely useless. The only way to bring it out of this locked state is a > power cylce with a POR (most of the case) or additionally a battery power > cycle which includes the loss of the secret keys. > At the next boot time some flags signals the security violation and a specific > register access sequence must be done to finaly bring this unit into life > again. Until this is done, there is no way to use it again as an RTC. > > But also without any enabled tamper detection sometimes this unit tends to > lock. And in this case the same steps must be done to bring it into life > again. > > The current implementation of the DryIce driver isn't able to unlock the > device successfully in the case it is locked somehow. Only a full power cycle > including *battery power* can help in this case. > > The attached change set adds the required routines to be able to unlock the > DryIce unit in the case the driver detects a locked unit. This includes > unlocking it if it is locked by accident or malfunction and not by a real > security violation. > > The last patch of this series is for reference only and should not be part > of the kernel. It just adds some code to force a locked DryIce unit to check > if the new routines are able to unlock it again. This code was required > because I had no hardware which really uses the tamper detection features of > this unit. > > This is the 2nd version of the patch series. Hopefully I addressed all > comments > from Alexandre. > > In this version I added a new patch which replaces all __raw* register > functions > as recommended by Alexandre. > > Comments are welcome. >
I've applied 1-5 after fixing a few parenthesis alignments you missed. I've also reworked the commit subject prefix to the more concise "rtc: imdi:" and you forgot the commit message in patch 2, you can check it here: https://github.com/alexandrebelloni/linux/commit/eff76de33878687dc1877f40ac2cc34794f499e0 Tell me if you have any objection. BTW, I guess your email address has been recycled as patchwork recognize it has belonging to Juergen Beisert ;) -- Alexandre Belloni, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
