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authorStephen Boyd <stephen.boyd@linaro.org>2018-01-31 05:36:16 +0300
committerRob Herring <robh@kernel.org>2018-02-12 17:37:58 +0300
commitbd6f2fd5a1d52198468c5cdc3c2472362dff5aaa (patch)
treed3c8291e9aab78edd712a2345e09052a4eceb607 /include/linux/of.h
parent7928b2cbe55b2a410a0f5c1f154610059c57b1b2 (diff)
downloadlinux-bd6f2fd5a1d52198468c5cdc3c2472362dff5aaa.tar.xz
of: Support parsing phandle argument lists through a nexus node
Platforms like 96boards have a standardized connector/expansion slot that exposes signals like GPIOs to expansion boards in an SoC agnostic way. We'd like the DT overlays for the expansion boards to be written once without knowledge of the SoC on the other side of the connector. This avoids the unscalable combinatorial explosion of a different DT overlay for each expansion board and SoC pair. We need a way to describe the GPIOs routed through the connector in an SoC agnostic way. Let's introduce nexus property parsing into the OF core to do this. This is largely based on the interrupt nexus support we already have. This allows us to remap a phandle list in a consumer node (e.g. reset-gpios) through a connector in a generic way (e.g. via gpio-map). Do this in a generic routine so that we can remap any sort of variable length phandle list. Taking GPIOs as an example, the connector would be a GPIO nexus, supporting the remapping of a GPIO specifier space to multiple GPIO providers on the SoC. DT would look as shown below, where 'soc_gpio1' and 'soc_gpio2' are inside the SoC, 'connector' is an expansion port where boards can be plugged in, and 'expansion_device' is a device on the expansion board. soc { soc_gpio1: gpio-controller1 { #gpio-cells = <2>; }; soc_gpio2: gpio-controller2 { #gpio-cells = <2>; }; }; connector: connector { #gpio-cells = <2>; gpio-map = <0 0 &soc_gpio1 1 0>, <1 0 &soc_gpio2 4 0>, <2 0 &soc_gpio1 3 0>, <3 0 &soc_gpio2 2 0>; gpio-map-mask = <0xf 0x0>; gpio-map-pass-thru = <0x0 0x1> }; expansion_device { reset-gpios = <&connector 2 GPIO_ACTIVE_LOW>; }; The GPIO core would use of_parse_phandle_with_args_map() instead of of_parse_phandle_with_args() and arrive at the same type of result, a phandle and argument list. The difference is that the phandle and arguments will be remapped through the nexus node to the underlying SoC GPIO controller node. In the example above, we would remap 'reset-gpios' from <&connector 2 GPIO_ACTIVE_LOW> to <&soc_gpio1 3 GPIO_ACTIVE_LOW>. Cc: Pantelis Antoniou <pantelis.antoniou@konsulko.com> Cc: Linus Walleij <linus.walleij@linaro.org> Cc: Mark Brown <broonie@kernel.org> Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org> Signed-off-by: Rob Herring <robh@kernel.org>
Diffstat (limited to 'include/linux/of.h')
-rw-r--r--include/linux/of.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/of.h b/include/linux/of.h
index da1ee95241c1..7258bbc85e4e 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -363,6 +363,9 @@ extern struct device_node *of_parse_phandle(const struct device_node *np,
extern int of_parse_phandle_with_args(const struct device_node *np,
const char *list_name, const char *cells_name, int index,
struct of_phandle_args *out_args);
+extern int of_parse_phandle_with_args_map(const struct device_node *np,
+ const char *list_name, const char *stem_name, int index,
+ struct of_phandle_args *out_args);
extern int of_parse_phandle_with_fixed_args(const struct device_node *np,
const char *list_name, int cells_count, int index,
struct of_phandle_args *out_args);
@@ -815,6 +818,15 @@ static inline int of_parse_phandle_with_args(const struct device_node *np,
return -ENOSYS;
}
+static inline int of_parse_phandle_with_args_map(const struct device_node *np,
+ const char *list_name,
+ const char *stem_name,
+ int index,
+ struct of_phandle_args *out_args)
+{
+ return -ENOSYS;
+}
+
static inline int of_parse_phandle_with_fixed_args(const struct device_node *np,
const char *list_name, int cells_count, int index,
struct of_phandle_args *out_args)