coresight: etm: retrieve and handle atclk
authorLinus Walleij <linus.walleij@linaro.org>
Tue, 19 May 2015 16:55:14 +0000 (10:55 -0600)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sun, 24 May 2015 18:12:08 +0000 (11:12 -0700)
commitd1839e68777316cc607d1d3f82579046ca945958
tree0b02b9f0e59571e903e81d9984f42539220c61cb
parent32398ef6f4745b2098d93f32e2c89e0286ab45fe
coresight: etm: retrieve and handle atclk

As can be seen from the datasheet of the CoreSight
Components, DDI0401C A.1.1 the ETM has a clock signal
apart from the AHB interconnect ("amba_pclk", that we're
already handling) called ATCLK, ARM Trace Clock, that SoC
implementers may provide from an entirely different clock
source. So to model this correctly create an optional
path for handling ATCLK alongside the PCLK so we don't
break old platforms that only define PCLK ("amba_pclk") but
still makes it possible for SoCs that have both clock signals
(such as the DB8500) to fetch and prepare/enable/disable/
unprepare both clocks.

The ATCLK is enabled and disabled using the runtime PM
callbacks.

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/hwtracing/coresight/coresight-etm.h
drivers/hwtracing/coresight/coresight-etm3x.c