On Wed, Feb 01, 2017 at 02:43:02AM +0800, Fu Wei wrote:
On 31 January 2017 at 01:49, Mark Rutland mark.rutland@arm.com wrote:
On Thu, Jan 26, 2017 at 01:49:03PM +0800, Fu Wei wrote:
On 26 January 2017 at 01:25, Mark Rutland mark.rutland@arm.com wrote:
On Wed, Jan 25, 2017 at 02:46:12PM +0800, Fu Wei wrote:
On 25 January 2017 at 01:24, Mark Rutland mark.rutland@arm.com wrote:
On Wed, Jan 18, 2017 at 09:25:32PM +0800, fu.wei@linaro.org wrote: > From: Fu Wei fu.wei@linaro.org
But according to another document(ARMv8-A Foundation Platform User Guide ARM DUI0677K), Table 3-2 ARMv8-A Foundation Platform memory map (continued)
AP_REFCLK CNTBase0, Generic Timer 64KB S AP_REFCLK CNTBase1, Generic Timer 64KB S/NS
Dose it means the timer frame 0 can be accessed in SECURE status only, and the timer frame 1 can be accessed in both status?
That does appear to be what it says.
I assume in this case CNTCTLBase.CNTSAR<0> is RES0.
And because Linux kernel is running on Non-secure EL1, so should we skip "SECURE" timer in Linux?
I guess you mean by checking the GTx Common flags, to see if the timer is secure? Yes, we must skip those.
Yes, exactly.
I think we can check the GTx Common flags, if the timer is set as SECURE, this driver should just skip this timer.
I completely agree that we must skip these.
Looking further at this, the ACPI spec is sorely lacking any statement as to the configuration of CNTCTLBase.{CNTSAR,CNTTIDR,CNTACR}, so it's not clear if we can access anything in a frame, even if it is listed as being a non-secure timer.
I think we need a stronger statement here. Otherwise, we will encounter problems. Linux currently assumes that CNTCTLBase.CNTACR<N> is writeable, given a non-secure frame N. This is only the case if CNTCTLBase.CNTSAR.NS<N> == 1.
the original driver has checked these registers, but the problem is: What if the timer frame is designed to be a secure timer, all the register in this frame is only can be accessed in secure status, just like foundation model? Note: for foundation model, Please check Table 3-1 Access permissions of 3.1 ARMv8-A Foundation Platform memory map in ARMv8-A Foundation Platform User Guide
So I think we should check the GTDT first, if it's not a secure timer, then we can go on checking CNTSAR. :-)
I've clearly confused matters here. I completely agree that we must skip timers the GTDT descrbies as secure.
My complaint here is that the spec does not explicitly state that CNTCTLBase.CNTSAR.NS<N> must be set for timers *not* marked as secure (though I believe that is the intent). That is a spec issue, not a code issue.
We unfortunately can't check CNTNSAR, as it is secure-only. :(
Thanks, Mark.