| Message ID | 20220907110852.5673-1-michal.orzel@amd.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [ImageBuilder,v2,1/2] scripts/common: Introduce phandle_next and get_next_phandle() | expand |
On Wed, 7 Sep 2022, Michal Orzel wrote: > When dealing with device trees, we need to have a solution to add > custom phandles to the nodes we create/modify. Add a global variable > phandle_next to act as a countdown counter starting with the highest > valid phandle value 0xfffffffe. Add a new function get_next_phandle > to get a value of the next available phandle and set it to a variable > whose name is passed as a first argument. The global counter will be > decremented with each call to this function. > > Signed-off-by: Michal Orzel <michal.orzel@amd.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> > --- > To make the interface to phandle_next as simple as possible, we just > need a single function that will get us the next phandle and update the > global counter. That is why we cannot use the following: > - "phandle=$(get_next_phandle)" as a subshell cannot modify the environment > of its parent shell, > - making use of return statement as it only works with values up to 255 > > The current solution with passing a variable name to a function that > will modify its value using eval is the simplest one and serves our purpose. I love the trick > Changes in v2: > - new patch > --- > scripts/common | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/scripts/common b/scripts/common > index 68938beb8557..25c041270c29 100644 > --- a/scripts/common > +++ b/scripts/common > @@ -13,6 +13,9 @@ > tmp_files=() > tmp_dirs=() > > +# Highest valid phandle. Will be decremented with each call to get_next_phandle > +phandle_next="0xfffffffe" > + > function remove_tmp_files() > { > for i in "${tmp_files[@]}" > @@ -26,6 +29,14 @@ function remove_tmp_files() > done > } > > +# Get next phandle and set it as a value (in hex) of a variable whose name is > +# passed as a first argument. Decrement global counter phandle_next. > +function get_next_phandle() > +{ > + eval "$1=$(printf "0x%x" $phandle_next)" > + phandle_next=$(( $phandle_next - 1 )) > +} > + > function sanity_check_partial_dts() > { > local domU_passthrough_path="$1" > -- > 2.25.1 >
diff --git a/scripts/common b/scripts/common index 68938beb8557..25c041270c29 100644 --- a/scripts/common +++ b/scripts/common @@ -13,6 +13,9 @@ tmp_files=() tmp_dirs=() +# Highest valid phandle. Will be decremented with each call to get_next_phandle +phandle_next="0xfffffffe" + function remove_tmp_files() { for i in "${tmp_files[@]}" @@ -26,6 +29,14 @@ function remove_tmp_files() done } +# Get next phandle and set it as a value (in hex) of a variable whose name is +# passed as a first argument. Decrement global counter phandle_next. +function get_next_phandle() +{ + eval "$1=$(printf "0x%x" $phandle_next)" + phandle_next=$(( $phandle_next - 1 )) +} + function sanity_check_partial_dts() { local domU_passthrough_path="$1"
When dealing with device trees, we need to have a solution to add custom phandles to the nodes we create/modify. Add a global variable phandle_next to act as a countdown counter starting with the highest valid phandle value 0xfffffffe. Add a new function get_next_phandle to get a value of the next available phandle and set it to a variable whose name is passed as a first argument. The global counter will be decremented with each call to this function. Signed-off-by: Michal Orzel <michal.orzel@amd.com> --- To make the interface to phandle_next as simple as possible, we just need a single function that will get us the next phandle and update the global counter. That is why we cannot use the following: - "phandle=$(get_next_phandle)" as a subshell cannot modify the environment of its parent shell, - making use of return statement as it only works with values up to 255 The current solution with passing a variable name to a function that will modify its value using eval is the simplest one and serves our purpose. Changes in v2: - new patch --- scripts/common | 11 +++++++++++ 1 file changed, 11 insertions(+)