On Fri, Jul 29, 2016 at 11:24:50PM +0200, Rafał Miłecki wrote:

On 29 July 2016 at 15:15, Mark Rutland [off-list ref] wrote:

quoted

On Fri, Jul 29, 2016 at 02:58:32PM +0200, Rafał Miłecki wrote:

quoted

From: Rafał Miłecki <rafal@milecki.pl>

This clock is present on cheaper Northstar devices like BCM53573 or
BCM47189 using Corex-A7. This driver uses PMU (Power Management Unit)
to calculate clock rate and allows using it in a generic (clk_*) way.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
 .../devicetree/bindings/clock/brcm,ns-ilp.txt      |  28 ++++
 drivers/clk/bcm/Makefile                           |   1 +
 drivers/clk/bcm/clk-ns-ilp.c                       | 146 +++++++++++++++++++++
 3 files changed, 175 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/brcm,ns-ilp.txt
 create mode 100644 drivers/clk/bcm/clk-ns-ilp.c

diff --git a/Documentation/devicetree/bindings/clock/brcm,ns-ilp.txt b/Documentation/devicetree/bindings/clock/brcm,ns-ilp.txt
new file mode 100644
index 0000000..c4df38e
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/brcm,ns-ilp.txt

@@ -0,0 +1,28 @@
+Broadcom Northstar ILP clock
+============================
+
+This binding uses the common clock binding:
+    Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+This binding is used for ILP clock on Broadcom Northstar devices using
+Corex-A7 CPU. ILP clock depends on ALP one and has to be calculated on
+runtime.
+
+Required properties:
+- compatible: "brcm,ns-ilp"
+- reg: iomem address range of PMU (Power Management Unit)
+- reg-names: "pmu", the only needed & supported reg right now

From the commit message and binding description, it sounds like there
should be a binding for the PMU, and that should cover the clocks
required/exported by the PMU.

This is a bit of problem, because PMU handles a lot of different stuff
and is used by various drivers. Some examples of what you can do
with/find on a PMU:
1) Power management
2) Watchdog
3) Timer
4) XTAL
5) PLLs
6) Control registers for some ARM debugging (whatever it is), UART, JTAG, more

The organisation of subsystems in Libnux shouldn't affect the binding in
this manner.

There'll likely be shared resources (e.g. register ranges), and you need
knowledge of the entire PMU to operate the sub-resources (and their
potentially shared dependencies) without conflict.

While you might one sub-nodes on a larger PMU node, these should
certainly not be entirely separate nodes and/or bindings.

quoted

quoted

+- clocks: should reference an ALP clock
+- clock-names: "alp", the only needed & supported clock right now
+- #clock-cells: should be <0>

How many clocks does the PMU output, including the ILP clock?

Well, ALP clock (AKA XTAL clock) is definitely part of PMU. It's a
fixed rate clock with rate specific to the chip.

I think ILP is also part of PMU (again: I don't have datasheets) as
PMU has this ALP_PER_4ILP register.

Ok. Is that output from the PMU, or is it strictly internal?

From Broadcom's SDK I can say they also have "ARM debug unit" on some
chipsets. It requires enabling "ARM debug clk" to operate which is
handled by PMU as well.

Likewise?

Thanks,
Mark.