linux-kernel - [RFC PATCH 3/3] misc: SRAM: Add option to map SRAM to allow code execution

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Date:	Mon, 9 May 2016 16:41:51 -0500
From:	Dave Gerlach <d-gerlach@...com>
To:	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>
CC:	Russ Dill <russ.dill@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Arnd Bergmann <arnd@...db.de>, Shawn Guo <shawnguo@...nel.org>,
	Tony Lindgren <tony@...mide.com>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	Russell King <linux@....linux.org.uk>,
	Nishanth Menon <nm@...com>, Dave Gerlach <d-gerlach@...com>,
	Russ Dill <Russ.Dill@...com>
Subject: [RFC PATCH 3/3] misc: SRAM: Add option to map SRAM to allow code execution

Allow option for mapping SRAM as executable. DT node can specify
"memory-exec" and "memory-exec-nocache" to also map it as non-cached.
This is useful for platforms using the sram driver that need to run
PM code from sram like several ARM platforms.

Signed-off-by: Russ Dill <Russ.Dill@...com>
Signed-off-by: Dave Gerlach <d-gerlach@...com>
---
 Documentation/devicetree/bindings/sram/sram.txt | 2 ++
 drivers/misc/sram.c                             | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/sram/sram.txt b/Documentation/devicetree/bindings/sram/sram.txt
index 227e3a341af1..1f1d0aa52703 100644
--- a/Documentation/devicetree/bindings/sram/sram.txt
+++ b/Documentation/devicetree/bindings/sram/sram.txt
@@ -29,6 +29,8 @@ Optional properties in the sram node:
 
 - no-memory-wc : the flag indicating, that SRAM memory region has not to
                  be remapped as write combining. WC is used by default.
+- memory-exec : map range to allow code execution
+- memory-exec-nocache : map range to allow code execution and also non-cached
 
 Required properties in the area nodes:
 
diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
index 69cdabea9c03..7f00ba574a83 100644
--- a/drivers/misc/sram.c
+++ b/drivers/misc/sram.c
@@ -362,6 +362,14 @@ static int sram_probe(struct platform_device *pdev)
 
 	if (of_property_read_bool(pdev->dev.of_node, "no-memory-wc"))
 		sram->virt_base = devm_ioremap(sram->dev, res->start, size);
+	else if (of_property_read_bool(pdev->dev.of_node, "memory-exec"))
+		sram->virt_base = devm_ioremap_exec(sram->dev, res->start,
+						    size);
+	else if (of_property_read_bool(pdev->dev.of_node,
+				       "memory-exec-nocache"))
+		sram->virt_base = devm_ioremap_exec_nocache(sram->dev,
+							    res->start,
+							    size);
 	else
 		sram->virt_base = devm_ioremap_wc(sram->dev, res->start, size);
 	if (IS_ERR(sram->virt_base))
-- 
2.7.3