On Wed, Apr 05, 2017 at 10:25:26AM +0530, Rajendra Nayak wrote: > Each of the CPU clusters (Power and Perf) on msm8996 are > clocked via 2 PLLs, a primary and alternate. There are also > 2 Mux'es, a primary and secondary all connected together > as shown below > > +-------+ > XO | | > +------------------>0 | > | | > PLL/2 | SMUX +----+ > +------->1 | | > | | | | > | +-------+ | +-------+ > | +---->0 | > | | | > +---------------+ | +----------->1 | CPU clk > |Primary PLL +----+ PLL_EARLY | | +------> > | +------+-----------+ +------>2 PMUX | > +---------------+ | | | | > | +------+ | +-->3 | > +--^+ ACD +-----+ | +-------+ > +---------------+ +------+ | > |Alt PLL | | > | +---------------------------+ > +---------------+ PLL_EARLY > > The primary PLL is what drives the CPU clk, except for times > when we are reprogramming the PLL itself (for rate changes) when > we temporarily switch to an alternate PLL. A subsequent patch adds > support to switch between primary and alternate PLL during rate > changes. > > The primary PLL operates on a single VCO range, between 600Mhz > and 3Ghz. However the CPUs do support OPPs with frequencies > between 300Mhz and 600Mhz. In order to support running the CPUs > at those frequencies we end up having to lock the PLL at twice > the rate and drive the CPU clk via the PLL/2 output and SMUX. > > So for frequencies above 600Mhz we follow the following path > Primary PLL --> PLL_EARLY --> PMUX(1) --> CPU clk > and for frequencies between 300Mhz and 600Mhz we follow > Primary PLL --> PLL/2 --> SMUX(1) --> PMUX(0) --> CPU clk > Support for this is added in a subsequent patch as well. > > ACD stands for Adaptive Clock Distribution and is used to > detect voltage droops. We do not add support for ACD as yet. > This can be added at a later point as needed. > > Signed-off-by: Rajendra Nayak <rnayak@xxxxxxxxxxxxxx> > --- > .../devicetree/bindings/clock/qcom,kryocc.txt | 17 + Acked-by: Rob Herring <robh@xxxxxxxxxx> > drivers/clk/qcom/Kconfig | 8 + > drivers/clk/qcom/Makefile | 1 + > drivers/clk/qcom/clk-cpu-8996.c | 388 +++++++++++++++++++++ > 4 files changed, 414 insertions(+) > create mode 100644 Documentation/devicetree/bindings/clock/qcom,kryocc.txt > create mode 100644 drivers/clk/qcom/clk-cpu-8996.c -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
