On 3 March 2014 17:02, Tomasz Figa <tomasz.figa@xxxxxxxxx> wrote:
This patch introduces generic code to perform power domain look-up using
device tree and automatically bind devices to their power domains.
Generic device tree binding is introduced to specify power domains of
devices in their device tree nodes.
Backwards compatibility with legacy Samsung-specific power domain
bindings is provided, but for now the new code is not compiled when
CONFIG_ARCH_EXYNOS is selected to avoid collision with legacy code. This
will change as soon as Exynos power domain code gets converted to use
the generic framework in further patch.
Signed-off-by: Tomasz Figa <tomasz.figa@xxxxxxxxx>
---
.../devicetree/bindings/power/power_domain.txt | 51 ++++
drivers/base/power/domain.c | 298 +++++++++++++++++++++
include/linux/pm_domain.h | 46 ++++
kernel/power/Kconfig | 4 +
4 files changed, 399 insertions(+)
create mode 100644 Documentation/devicetree/bindings/power/power_domain.txt
diff --git a/Documentation/devicetree/bindings/power/power_domain.txt b/Documentation/devicetree/bindings/power/power_domain.txt
new file mode 100644
index 0000000..93be5d9
--- /dev/null
+++ b/Documentation/devicetree/bindings/power/power_domain.txt
@@ -0,0 +1,51 @@
+* Generic power domains
+
+System on chip designs are often divided into multiple power domains that
+can be used for power gating of selected IP blocks for power saving by
+reduced leakage current.
+
+This device tree binding can be used to bind power domain consumer devices
+with their power domains provided by power domain providers. A power domain
+provider can be represented by any node in the device tree and can provide
+one or more power domains. A consumer node can refer to the provider by
+a phandle and a set of phandle arguments (so called power domain specifier)
+of length specified by #power-domain-cells property in the power domain
+provider node.
+
+==Power domain providers==
+
+Required properties:
+ - #power-domain-cells : Number of cells in a power domain specifier;
+ Typically 0 for nodes representing a single power domain and 1 for nodes
+ providing multiple power domains (e.g. power controllers), but can be
+ any value as specified by device tree binding documentation of particular
+ provider.
I am trying to understand if using a value > 1, ever would make sense.
Wouldn't that mean each consumer (device) would actually be a part of
more than one power domain? That won't work, right!?
Additionally, there are no corresponding parsing method (like
of_genpd_xlate_onecell() ) that support more than one cell.