[PATCHv4] arm: l2x0: add PMU support

[Russell King - ARM Linux]

On Wed, Aug 31, 2016 at 03:23:36PM +0100, Mark Rutland wrote:
> The L2C-220 (AKA L220) and L2C-310 (AKA PL310) cache controllers feature
> a Performance Monitoring Unit (PMU), which can be useful for tuning
> and/or debugging. This hardware is always present and the relevant
> registers are accessible to non-secure accesses. Thus, no special
> firmware interface is necessary.
> 
> This patch adds support for the PMU, plugging into the usual perf
> infrastructure. The overflow interrupt is not always available (e.g. on
> RealView PBX A9 it is not wired up at all), and the hardware counters
> saturate, so the driver does not make use of this. Instead, the driver
> periodically polls and reset counters as required to avoid losing
> events due to saturation.
> 
> Signed-off-by: Mark Rutland <mark.rutland at arm.com>
> Acked-by: Pawel Moll <pawel.moll at arm.com>
> Cc: Kim Phillips <kim.phillips at arm.com>
> Cc: Russell King <linux at armlinux.org.uk>
> Cc: Will Deacon <will.deacon at arm.com>

Much better, thanks.  When you're happy, please put it in the patch
system, thanks.

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