linux-kernel - [PATCH v3 1/3] include/of_fdt.h: add a weak arch hook to update fdt pgprot

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Date:   Thu, 16 May 2019 18:28:15 +0800
From:   Hsin-Yi Wang <hsinyi@...omium.org>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Frank Rowand <frowand.list@...il.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Miles Chen <miles.chen@...iatek.com>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        James Morse <james.morse@....com>,
        Andrew Murray <andrew.murray@....com>,
        Mark Rutland <mark.rutland@....com>,
        Chintan Pandya <cpandya@...eaurora.org>,
        Jun Yao <yaojun8558363@...il.com>, Yu Zhao <yuzhao@...gle.com>,
        Robin Murphy <robin.murphy@....com>,
        Laura Abbott <labbott@...hat.com>,
        Stephen Boyd <swboyd@...omium.org>,
        Kees Cook <keescook@...omium.org>
Subject: [PATCH v3 1/3] include/of_fdt.h: add a weak arch hook to update fdt pgprot

Does nothing as default, arch can implement their function to map
fdt to RO/RW. This is convenient if arch map fdt to RO during init
but needs to write fdt in some special cases after that.

Signed-off-by: Hsin-Yi Wang <hsinyi@...omium.org>
---
 drivers/of/fdt.c       | 13 +++++++++++++
 include/linux/of_fdt.h |  2 ++
 2 files changed, 15 insertions(+)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index de893c9616a1..e84971d1e9ea 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -30,6 +30,19 @@
 
 #include "of_private.h"
 
+/*
+ * update_fdt_pgprot - Arch hook for changing fdt pgprot
+ *
+ * @prot: page protection flags for fdt
+ *
+ * Architecture can implement this function if they want to chagne
+ * fdt page protection flags before or after doing modification and
+ * fixups to fdt.
+ *
+ * Default does nothing.
+ */
+__weak void update_fdt_pgprot(pgprot_t prot) {}
+
 /*
  * of_fdt_limit_memory - limit the number of regions in the /memory node
  * @limit: maximum entries
diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
index a713e5d156d8..406c3e7b2b75 100644
--- a/include/linux/of_fdt.h
+++ b/include/linux/of_fdt.h
@@ -109,5 +109,7 @@ static inline void unflatten_device_tree(void) {}
 static inline void unflatten_and_copy_device_tree(void) {}
 #endif /* CONFIG_OF_EARLY_FLATTREE */
 
+extern void update_fdt_pgprot(pgprot_t prot);
+
 #endif /* __ASSEMBLY__ */
 #endif /* _LINUX_OF_FDT_H */
-- 
2.20.1